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Sample records for b-type cytochromes specific

  1. Toward a chemical mechanism of proton pumping by the B-type cytochrome c oxidases: application of density functional theory to cytochrome ba3 of Thermus thermophilus.

    Science.gov (United States)

    Fee, James A; Case, David A; Noodleman, Louis

    2008-11-12

    A mechanism for proton pumping by the B-type cytochrome c oxidases is presented in which one proton is pumped in conjunction with the weakly exergonic, two-electron reduction of Fe-bound O 2 to the Fe-Cu bridging peroxodianion and three protons are pumped in conjunction with the highly exergonic, two-electron reduction of Fe(III)- (-)O-O (-)-Cu(II) to form water and the active oxidized enzyme, Fe(III)- (-)OH,Cu(II). The scheme is based on the active-site structure of cytochrome ba 3 from Thermus thermophilus, which is considered to be both necessary and sufficient for coupled O 2 reduction and proton pumping when appropriate gates are in place (not included in the model). Fourteen detailed structures obtained from density functional theory (DFT) geometry optimization are presented that are reasonably thought to occur during the four-electron reduction of O 2. Each proton-pumping step takes place when a proton resides on the imidazole ring of I-His376 and the large active-site cluster has a net charge of +1 due to an uncompensated, positive charge formally associated with Cu B. Four types of DFT were applied to determine the energy of each intermediate, and standard thermochemical approaches were used to obtain the reaction free energies for each step in the catalytic cycle. This application of DFT generally conforms with previously suggested criteria for a valid model (Siegbahn, P. E. M.; Blomberg, M. A. R. Chem. Rev. 2000, 100, 421-437) and shows how the chemistry of O 2 reduction in the heme a 3 -Cu B dinuclear center can be harnessed to generate an electrochemical proton gradient across the lipid bilayer.

  2. Water exit pathways and proton pumping mechanism in B-type cytochrome c oxidase from molecular dynamics simulations.

    Science.gov (United States)

    Yang, Longhua; Skjevik, Åge A; Han Du, Wen-Ge; Noodleman, Louis; Walker, Ross C; Götz, Andreas W

    2016-09-01

    Cytochrome c oxidase (CcO) is a vital enzyme that catalyzes the reduction of molecular oxygen to water and pumps protons across mitochondrial and bacterial membranes. While proton uptake channels as well as water exit channels have been identified for A-type CcOs, the means by which water and protons exit B-type CcOs remain unclear. In this work, we investigate potential mechanisms for proton transport above the dinuclear center (DNC) in ba3-type CcO of Thermus thermophilus. Using long-time scale, all-atom molecular dynamics (MD) simulations for several relevant protonation states, we identify a potential mechanism for proton transport that involves propionate A of the active site heme a3 and residues Asp372, His376 and Glu126(II), with residue His376 acting as the proton-loading site. The proposed proton transport process involves a rotation of residue His376 and is in line with experimental findings. We also demonstrate how the strength of the salt bridge between residues Arg225 and Asp287 depends on the protonation state and that this salt bridge is unlikely to act as a simple electrostatic gate that prevents proton backflow. We identify two water exit pathways that connect the water pool above the DNC to the outer P-side of the membrane, which can potentially also act as proton exit transport pathways. Importantly, these water exit pathways can be blocked by narrowing the entrance channel between residues Gln151(II) and Arg449/Arg450 or by obstructing the entrance through a conformational change of residue Tyr136, respectively, both of which seem to be affected by protonation of residue His376.

  3. Proton transfer in the K-channel analog of B-type Cytochrome c oxidase from Thermus thermophilus.

    Science.gov (United States)

    Woelke, Anna Lena; Wagner, Anke; Galstyan, Gegham; Meyer, Tim; Knapp, Ernst-Walter

    2014-11-04

    A key enzyme in aerobic metabolism is cytochrome c oxidase (CcO), which catalyzes the reduction of molecular oxygen to water in the mitochondrial and bacterial membranes. Substrate electrons and protons are taken up from different sides of the membrane and protons are pumped across the membrane, thereby generating an electrochemical gradient. The well-studied A-type CcO uses two different entry channels for protons: the D-channel for all pumped and two consumed protons, and the K-channel for the other two consumed protons. In contrast, the B-type CcO uses only a single proton input channel for all consumed and pumped protons. It has the same location as the A-type K-channel (and thus is named the K-channel analog) without sharing any significant sequence homology. In this study, we performed molecular-dynamics simulations and electrostatic calculations to characterize the K-channel analog in terms of its energetic requirements and functionalities. The function of Glu-15B as a proton sink at the channel entrance is demonstrated by its rotational movement out of the channel when it is deprotonated and by its high pKA value when it points inside the channel. Tyr-244 in the middle of the channel is identified as the valve that ensures unidirectional proton transfer, as it moves inside the hydrogen-bond gap of the K-channel analog only while being deprotonated. The electrostatic energy landscape was calculated for all proton-transfer steps in the K-channel analog, which functions via proton-hole transfer. Overall, the K-channel analog has a very stable geometry without large energy barriers.

  4. Comparison of the backbone dynamics of wild-type Hydrogenobacter thermophilus cytochrome c{sub 552} and its b-type variant

    Energy Technology Data Exchange (ETDEWEB)

    Tozawa, Kaeko; Ferguson, Stuart J.; Redfield, Christina, E-mail: christina.redfield@bioch.ox.ac.uk [University of Oxford, Department of Biochemistry (United Kingdom); Smith, Lorna J., E-mail: lorna.smith@chem.ox.ac.uk [University of Oxford, Department of Chemistry (United Kingdom)

    2015-06-15

    Cytochrome c{sub 552} from the thermophilic bacterium Hydrogenobacter thermophilus is a typical c-type cytochrome which binds heme covalently via two thioether bonds between the two heme vinyl groups and two cysteine thiol groups in a CXXCH sequence motif. This protein was converted to a b-type cytochrome by substitution of the two cysteine residues by alanines (Tomlinson and Ferguson in Proc Natl Acad Sci USA 97:5156–5160, 2000a). To probe the significance of the covalent attachment of the heme in the c-type protein, {sup 15}N relaxation and hydrogen exchange studies have been performed for the wild-type and b-type proteins. The two variants share very similar backbone dynamic properties, both proteins showing high {sup 15}N order parameters in the four main helices, with reduced values in an exposed loop region (residues 18–21), and at the C-terminal residue Lys80. Some subtle changes in chemical shift and hydrogen exchange protection are seen between the wild-type and b-type variant proteins, not only for residues at and neighbouring the mutation sites, but also for some residues in the heme binding pocket. Overall, the results suggest that the main role of the covalent linkages between the heme group and the protein chain must be to increase the stability of the protein.

  5. The B-type lamin is required for somatic repression of testis-specific gene clusters

    Science.gov (United States)

    Shevelyov, Y. Y.; Lavrov, S. A.; Mikhaylova, L. M.; Nurminsky, I. D.; Kulathinal, R. J.; Egorova, K. S.; Rozovsky, Y. M.; Nurminsky, D. I.

    2009-01-01

    Large clusters of coexpressed tissue-specific genes are abundant on chromosomes of diverse species. The genes coordinately misexpressed in diverse diseases are also found in similar clusters, suggesting that evolutionarily conserved mechanisms regulate expression of large multigenic regions both in normal development and in its pathological disruptions. Studies on individual loci suggest that silent clusters of coregulated genes are embedded in repressed chromatin domains, often localized to the nuclear periphery. To test this model at the genome-wide scale, we studied transcriptional regulation of large testis-specific gene clusters in somatic tissues of Drosophila. These gene clusters showed a drastic paucity of known expressed transgene insertions, indicating that they indeed are embedded in repressed chromatin. Bioinformatics analysis suggested the major role for the B-type lamin, LamDmo, in repression of large testis-specific gene clusters, showing that in somatic cells as many as three-quarters of these clusters interact with LamDmo. Ablation of LamDmo by using mutants and RNAi led to detachment of testis-specific clusters from nuclear envelope and to their selective transcriptional up-regulation in somatic cells, thus providing the first direct evidence for involvement of the B-type lamin in tissue-specific gene repression. Finally, we found that transcriptional activation of the lamina-bound testis-specific gene cluster in male germ line is coupled with its translocation away from the nuclear envelope. Our studies, which directly link nuclear architecture with coordinated regulation of tissue-specific genes, advance understanding of the mechanisms underlying both normal cell differentiation and developmental disorders caused by lesions in the B-type lamins and interacting proteins. PMID:19218438

  6. Impact of epitope specificity and precursor maturation in pro-B-type natriuretic peptide measurement

    DEFF Research Database (Denmark)

    Goetze, J.P.; Dahlstrom, U.; Alehagen, U.

    2008-01-01

    with different epitope specificities in a cohort of elderly patients presenting with symptoms associated with heart failure (n = 415). RESULTS: Comparison of N-terminal proBNP with proBNP 1-76 measurement in plasma revealed a high correlation on regression analysis (r(2) = 0.91, P ..., the proBNP 1-76 assay measured lower concentrations in the high range than the N-terminal proBNP assay. Correlations between assay measurements in a clinical setting were comparable for all the assays (r(2) approximately 0.57-0.83), and ROC analyses revealed area-under-the-curve values ranging between 0...... the impact of epitope specificity and precursor maturation on plasma measurement of proBNP-derived peptides. METHODS: We compared 2 assays, N-terminal proBNP and proBNP 1-76, in a randomly collected set of human plasma specimens (n = 370). Additionally, we evaluated the clinical performance of 4 assays...

  7. Thiol redox requirements and substrate specificities of recombinant cytochrome c assembly systems II and III.

    Science.gov (United States)

    Richard-Fogal, Cynthia L; San Francisco, Brian; Frawley, Elaine R; Kranz, Robert G

    2012-06-01

    The reconstitution of biosynthetic pathways from heterologous hosts can help define the minimal genetic requirements for pathway function and facilitate detailed mechanistic studies. Each of the three pathways for the assembly of cytochrome c in nature (called systems I, II, and III) has been shown to function recombinantly in Escherichia coli, covalently attaching heme to the cysteine residues of a CXXCH motif of a c-type cytochrome. However, recombinant systems I (CcmABCDEFGH) and II (CcsBA) function in the E. coli periplasm, while recombinant system III (CCHL) attaches heme to its cognate receptor in the cytoplasm of E. coli, which makes direct comparisons between the three systems difficult. Here we show that the human CCHL (with a secretion signal) attaches heme to the human cytochrome c (with a signal sequence) in the E. coli periplasm, which is bioenergetically (p-side) analogous to the mitochondrial intermembrane space. The human CCHL is specific for the human cytochrome c, whereas recombinant system II can attach heme to multiple non-cognate c-type cytochromes (possessing the CXXCH motif.) We also show that the recombinant periplasmic systems II and III use components of the natural E. coli periplasmic DsbC/DsbD thiol-reduction pathway. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.

  8. Tumor-specific expression of cytochrome P450 CYP1B1.

    Science.gov (United States)

    Murray, G I; Taylor, M C; McFadyen, M C; McKay, J A; Greenlee, W F; Burke, M D; Melvin, W T

    1997-07-15

    Cytochrome P450 CYP1B1 is a recently cloned dioxin-inducible form of the cytochrome P450 family of xenobiotic metabolizing enzymes. An antibody raised against a peptide specific for CYP1B1 was found to recognize CYP1B1 expressed in human lymphoblastoid cells but not to recognize other forms of cytochrome P450, particularly CYP1A1 and CYP1A2. Using this antibody, the cellular distribution and localization of CYP1B1 were investigated by immunohistochemistry in a range of malignant tumors and corresponding normal tissues. CYP1B1 was found to be expressed at a high frequency in a wide range of human cancers of different histogenetic types, including cancers of the breast, colon, lung, esophagus, skin, lymph node, brain, and testis. There was no detectable immunostaining for CYP1B1 in normal tissues. These results provide the basis for the development of novel methods of cancer diagnosis based on the identification of CYP1B1 in tumor cells and the development of anticancer drugs that are selectively activated in tumors by CYP1B1.

  9. Dendroctonus armandi (Curculionidae: Scolytinae) cytochrome P450s display tissue specificity and responses to host terpenoids.

    Science.gov (United States)

    Dai, Lulu; Ma, Mingyuan; Gao, Guanqun; Chen, Hui

    2016-11-01

    Bark beetles oxidize the defensive allelochemicals of their host trees both to detoxify them and convert them into components of their pheromone systems which were catalyzed by cytochrome P450 enzymes (CYPs) and occur in different tissues of the insect. We study P450 genes in the Chinese white pine beetle (Dendroctonus armandi), and some bio-information analysis was done for the full-length deduced amino acid sequences. The tissue specificity of these P450 genes was determined in three tissues (antenna, gut and reproductive organs). Differential expression of the P450 genes was observed between sexes, and within these significant differences exposed to stimuli (α-pinene (1:1 racemic mix), (S)-(-)-α-pinene, (S)-(-)-β-pinene, (+)-3-carene, (±)-limonene and turpentine oil) at 24h. Increased expression of P450 genes suggested that they play a role in the detoxification of monoterpenes released by the host trees. The different transcript accumulation patterns of these bark beetle P450 genes provided insight into ecological interactions of D. armandi with its host pine.

  10. Site-Specific Characterization of Cytochrome P450cam Conformations by Infrared Spectroscopy.

    Science.gov (United States)

    Basom, Edward J; Maj, Michał; Cho, Minhaeng; Thielges, Megan C

    2016-06-21

    Conformational changes are central to protein function but challenging to characterize with both high spatial and temporal precision. The inherently fast time scale and small chromophores of infrared (IR) spectroscopy are well-suited for characterization of potentially rapidly fluctuating environments, and when frequency-resolved probes are incorporated to overcome spectral congestion, enable characterization of specific sites in proteins. We selectively incorporated p-cyanophenylalanine (CNF) as a vibrational probe at five distinct locations in the enzyme cytochrome P450cam and used IR spectroscopy to characterize the environments in substrate and/or ligand complexes reflecting those in the catalytic cycle. Molecular dynamics (MD) simulations were performed to provide a structural basis for spectral interpretation. Together the experimental and simulation data suggest that the CN frequencies are sensitive to both long-range influences, resulting from the particular location of a residue within the enzyme, as well as short-range influences from hydrogen bonding and packing interactions. The IR spectra demonstrate that the environments and effects of substrate and/or ligand binding are different at each position probed and also provide evidence that a single site can experience multiple environments. This study illustrates how IR spectroscopy, when combined with the spectral decongestion and spatial selectivity afforded by CNF incorporation, provides detailed information about protein structural changes that underlie function.

  11. Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects.

    Science.gov (United States)

    Kovářová, Nikola; Pecina, Petr; Nůsková, Hana; Vrbacký, Marek; Zeviani, Massimo; Mráček, Tomáš; Viscomi, Carlo; Houštěk, Josef

    2016-04-01

    Mitochondrial protein SURF1 is a specific assembly factor of cytochrome c oxidase (COX), but its function is poorly understood. SURF1 gene mutations cause a severe COX deficiency manifesting as the Leigh syndrome in humans, whereas in mice SURF1(-/-) knockout leads only to a mild COX defect. We used SURF1(-/-) mouse model for detailed analysis of disturbed COX assembly and COX ability to incorporate into respiratory supercomplexes (SCs) in different tissues and fibroblasts. Furthermore, we compared fibroblasts from SURF1(-/-) mouse and SURF1 patients to reveal interspecies differences in kinetics of COX biogenesis using 2D electrophoresis, immunodetection, arrest of mitochondrial proteosynthesis and pulse-chase metabolic labeling. The crucial differences observed are an accumulation of abundant COX1 assembly intermediates, low content of COX monomer and preferential recruitment of COX into I-III2-IVn SCs in SURF1 patient fibroblasts, whereas SURF1(-/-) mouse fibroblasts were characterized by low content of COX1 assembly intermediates and milder decrease in COX monomer, which appeared more stable. This pattern was even less pronounced in SURF1(-/-) mouse liver and brain. Both the control and SURF1(-/-) mice revealed only negligible formation of the I-III2-IVn SCs and marked tissue differences in the contents of COX dimer and III2-IV SCs, also less noticeable in liver and brain than in heart and muscle. Our studies support the view that COX assembly is much more dependent on SURF1 in humans than in mice. We also demonstrate markedly lower ability of mouse COX to form I-III2-IVn supercomplexes, pointing to tissue-specific and species-specific differences in COX biogenesis.

  12. The BALB/c mouse B-cell response to pigeon cytochrome c initiates as a heteroclitic response specific for the self antigen mouse cytochrome c.

    Science.gov (United States)

    Minnerath, J M; Wakem, L P; Comfort, L L; Sherman, F; Jemmerson, R

    1995-01-01

    Direct evidence is presented in support of the longstanding but unproven hypothesis that B lymphocytes specific for self antigens (Ags) can be used in the immune response to foreign Ags. We show that the B cells in BALB/c mic responding early to pigeon cytochrome c (CYT) produce antibodies that recognize and bind the major antigenic site on mouse CYT with greater affinity than they bind pigeon CYT i.e., they are heteroclitic for the self Ag. Furthermore, these B cells express the same combination of immunoglobulin variable region (V) genes that are known to be used in B-cell recognition of mouse CYT. Over time, the response to pigeon CYT becomes more specific for the foreign Ag through the recruitment of B cells expressing different combinations of V genes and, possibly, somatic mutation of the mouse CYT specific B cells from early in the response. Cross-recognition of pigeon CYT by mouse CYT-specific B cells results from the sharing of critical amino acid residues by the two Ags. Although B-cell recognition of the self Ag, mouse CYT, is very specific, which limits the extent to which foreign Ags can cross-activate the autoreactive B cells, it is possible that polyreactive B cells to other self Ags may be used more frequently in response to foreign Ags. PMID:8618905

  13. Human hepatic cytochrome P450-specific metabolism of the organophosphorus pesticides methyl parathion and diazinon.

    Science.gov (United States)

    Ellison, Corie A; Tian, Yuan; Knaak, James B; Kostyniak, Paul J; Olson, James R

    2012-01-01

    Organophosphorus pesticides (OPs) are a public health concern due to their worldwide use and documented human exposures. Phosphorothioate OPs are metabolized by cytochrome P450s (P450s) through either a dearylation reaction to form an inactive metabolite, or through a desulfuration reaction to form an active oxon metabolite, which is a potent cholinesterase inhibitor. This study investigated the rate of desulfuration (activation) and dearylation (detoxification) of methyl parathion and diazinon in human liver microsomes. In addition, recombinant human P450s were used to determine the P450-specific kinetic parameters (K(m) and V(max)) for each compound for future use in refining human physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of OP exposure. The primary enzymes involved in bioactivation of methyl parathion were CYP2B6 (K(m) = 1.25 μM; V(max) = 9.78 nmol · min(-1) · nmol P450(-1)), CYP2C19 (K(m) = 1.03 μM; V(max) = 4.67 nmol · min(-1) · nmol P450(-1)), and CYP1A2 (K(m) = 1.96 μM; V(max) = 5.14 nmol · min(-1) · nmol P450(-1)), and the bioactivation of diazinon was mediated primarily by CYP1A1 (K(m) = 3.05 μM; V(max) = 2.35 nmol · min(-1) · nmol P450(-1)), CYP2C19 (K(m) = 7.74 μM; V(max) = 4.14 nmol · min(-1) · nmol P450(-1)), and CYP2B6 (K(m) = 14.83 μM; V(max) = 5.44 nmol · min(-1) · nmol P450(-1)). P450-mediated detoxification of methyl parathion only occurred to a limited extent with CYP1A2 (K(m) = 16.8 μM; V(max) = 1.38 nmol · min(-1) · nmol P450(-1)) and 3A4 (K(m) = 104 μM; V(max) = 5.15 nmol · min(-1) · nmol P450(-1)), whereas the major enzyme involved in diazinon detoxification was CYP2C19 (K(m) = 5.04 μM; V(max) = 5.58 nmol · min(-1) · nmol P450(-1)). The OP- and P450-specific kinetic values will be helpful for future use in refining human PBPK/PD models of OP exposure.

  14. Human cytochrome p450 enzyme specificity for the bioactivation of estragole and related alkenylbenzenes

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Punt, A.; Boersma, M.G.; Bogaards, J.J.P.; Fiamegos, Y.C.; Schilter, B.; Bladeren, van P.J.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2007-01-01

    Human cytochrome P450 enzymes involved in the bioactivation of estragole to its proximate carcinogen 1 '-hydroxyestragole were identified and compared to the enzymes of importance for 1'-hydroxylation of the related alkenylbenzenes methyleugenol and safrole. Incubations with Supersomes revealed that

  15. Human cytochrome P450 enzyme specificity for bioactivation of safrole to the proximate carcinogen 1'-hydroxysafrole

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Awad, H.M.; Boersma, M.G.; Brand, W.; Fiamegos, Y.C.; Beek, van T.A.; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2004-01-01

    In the present study, the cytochrome P450 mediated bioactivation of safrole to its proximate carcinogenic metabolite, 1'-hydroxysafrole, has been investigated for the purpose of identifying the human P450 enzymes involved. The 1'-hydroxylation of safrole was characterized in a variety of in vitro te

  16. Human cytochrome P450 enzyme specificity for the bioactivation of estragole and related alkenylbenzenes

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Punt, A.; Boersma, M.G.; Bogaards, J.J.P.; Fiamegos, Y.C.; Schilter, B.; Bladeren, P.J. van; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2007-01-01

    Human cytochrome P450 enzymes involved in the bioactivation of estragole to its proximate carcinogen 1′-hydroxyestragole were identified and compared to the enzymes of importance for 1′-hydroxylation of the related alkenylbenzenes methyleugenol and safrole. Incubations with Supersomes revealed that

  17. MITRAC7 Acts as a COX1-Specific Chaperone and Reveals a Checkpoint during Cytochrome c Oxidase Assembly.

    Science.gov (United States)

    Dennerlein, Sven; Oeljeklaus, Silke; Jans, Daniel; Hellwig, Christin; Bareth, Bettina; Jakobs, Stefan; Deckers, Markus; Warscheid, Bettina; Rehling, Peter

    2015-09-08

    Cytochrome c oxidase, the terminal enzyme of the respiratory chain, is assembled from mitochondria- and nuclear-encoded subunits. The MITRAC complex represents the central assembly intermediate during this process as it receives imported subunits and regulates mitochondrial translation of COX1 mRNA. The molecular processes that promote and regulate the progression of assembly downstream of MITRAC are still unknown. Here, we identify MITRAC7 as a constituent of a late form of MITRAC and as a COX1-specific chaperone. MITRAC7 is required for cytochrome c oxidase biogenesis. Surprisingly, loss of MITRAC7 or an increase in its amount causes selective cytochrome c oxidase deficiency in human cells. We demonstrate that increased MITRAC7 levels stabilize and trap COX1 in MITRAC, blocking progression in the assembly process. In contrast, MITRAC7 deficiency leads to turnover of newly synthesized COX1. Accordingly, MITRAC7 affects the biogenesis pathway by stabilizing newly synthesized COX1 in assembly intermediates, concomitantly preventing turnover.

  18. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

    Science.gov (United States)

    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress.

  19. The Use of Cytochrome b Gene as a Specific Marker of the Rat Meat (Rattus norvegicus on Meat and Meat Products

    Directory of Open Access Journals (Sweden)

    C. Sumantri

    2012-04-01

    Full Text Available Falsification of the origin of livestock meat and its processed with rat meat is a problem that must be overcome to ensure food safety. One way that is often used to detect forgeries by using cytochrome b gene as a marker. The purpose of this study was to create a specific primer derived from cytochrome b sequences in rat (Rattus norvegicus as the DNA marker to detect any contamination of rat meat on fresh livestock meat and its processed meat products. Meatballs were made from beef meat with the addition of rat 1%-25%, and the meatballs were obtained from traditional markets. DNA extraction was conducted from seven species (goat, chicken, cattle, sheep, pig, horse, and rat by using phenol-chloroform. The highest success rate in detecting the presence of rat meat in a mixture of beef meatballs at concentration of 15% was 100%. The specific fragment of cytochrome b gene in R. norvegicus has no similarity with the cytochrome b gene from six other species, so it can be used as molecular markers to detect the presence of rat meat contamination in the processed of meat products. Amplified fragment length for goats, chickens, cattle, sheep, pigs, horses, and rats 157, 227, 274, 331, 398, 439 and 603 bp respectively. The amplification of cytochrome b gene in seven species of animals with different fragment length indicated the specificity of cytochrome b gene sequences among species.

  20. 10-Undecynoic acid, an inhibitor of cytochrome P450 4A1, inhibits ethanolamine-specific phospholipid base exchange reaction in rat liver microsomes.

    Science.gov (United States)

    Lenart, J; Pikuła, S

    1999-01-01

    1,12-Dodecanedioic acid, the end-product of omega-hydroxylation of lauric acid, stimulates in a concentration dependent manner, phosphatidylethanolamine synthesis via ethanolamine-specific phospholipid base exchange reaction in rat liver endoplasmic reticulum. On the other hand, administration to rats of 10-undecynoic acid, a specific inhibitor of omega-hydroxylation reaction catalyzed by cytochrome P450 4A1, inhibits the ethanolamine-specific phospholipid base exchange activity by 30%. This is accompanied by a small but significant decrease in phosphatidylethanolamine content in the endoplasmic reticulum and inhibition of cytochrome P450 4A1. On the basis of these results it can be proposed that a functional relationship between cytochrome P450 4A1 and phosphatidylethanolamine synthesis exists in rat liver. Cytochrome P450 4A1 modulates the cellular level of lauric acid, an inhibitor of phospholipid synthesis. In turn, ethanolamine-specific phospholipid base exchange reaction provides molecular species of phospholipids, containing mainly long-chain polyunsaturated fatty acid moieties, required for the optimal activity of cytochrome P450 4A1.

  1. IDENTIFIKASI DAGING BABI MENGGUNAKAN METODE PCR-RFLP GEN Cytochrome b DAN PCR PRIMER SPESIFIK GEN AMELOGENIN (Pork Identification Using PCR-RFLP of Cytochrome b Gene and Species Specific PCR of Amelogenin Gene

    Directory of Open Access Journals (Sweden)

    Yuny Erwanto

    2013-03-01

    Full Text Available A polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP and species specific PCR methods had been applied for identifying pork in mixture of meat. Pork sample in various levels (1, 3, 5 and 10% was prepared in mixture with beef, chicken and mutton. The primary CYTb1 and CYTb2 were designed in the mitochondrial cytochrome b b (cytochrome b gene and PCR successfully amplified fragments of 359 bp. To distinguish pig species existence, the amplified PCR products of mitochondrial DNA were cut by BseDI restriction enzyme. The result showed that pig mitochondrial DNA was cut into 131 and 228 bp fragments. A polymerase chain reaction (PCR method based on the nucleotide sequence variation in the amelogenin gene has been chosen for the specific identification of pork DNAs in mixture meat. The primers designed generated specific fragments of 353 and 312 bp length for pork. The specificity of the primary designed was tested on 4 animal species including pig, cattle, chicken and goat species. Analysis of experimental mixture meat demonstrated that 1% of raw pork tissues could be detected using PCR-RFLP with BseDI restriction enzyme but detection using species-specific PCR showed the cross reactivity to beef, chicken and mutton. The cytochrome b PCR-RFLP species identification assay yielded excellent results for identification of pig species. PCR-RFLP is a potentially reliable technique for detection of the existence of pork in animal food product for Halal authentication. Keywords: Pork identification, cytochrome b, amelogenin, polymerase chain reaction   ABSTRAK   Penelitian ini dilakukan untuk mengaplikasikan metode deteksi daging babi dalam campuan daging dengan sapi, kambing dan ayam melalui PCR-RFLP dan PCR dengan primer spesifik untuk babi. Level kontaminasi daging babi dibuat sebesar 1, 3, 5 dan 10% dari total daging dalam campuran. Metode PCR-RFLP menggunakan sepasang primer yaitu gen cytochrome b dari mitokondria yang

  2. Neuron-specific specificity protein 4 bigenomically regulates the transcription of all mitochondria- and nucleus-encoded cytochrome c oxidase subunit genes in neurons.

    Science.gov (United States)

    Johar, Kaid; Priya, Anusha; Dhar, Shilpa; Liu, Qiuli; Wong-Riley, Margaret T T

    2013-11-01

    Neurons are highly dependent on oxidative metabolism for their energy supply, and cytochrome c oxidase (COX) is a key energy-generating enzyme in the mitochondria. A unique feature of COX is that it is one of only four proteins in mammalian cells that are bigenomically regulated. Of its thirteen subunits, three are encoded in the mitochondrial genome and ten are nuclear-encoded on nine different chromosomes. The mechanism of regulating this multisubunit, bigenomic enzyme poses a distinct challenge. In recent years, we found that nuclear respiratory factors 1 and 2 (NRF-1 and NRF-2) mediate such bigenomic coordination. The latest candidate is the specificity factor (Sp) family of proteins. In N2a cells, we found that Sp1 regulates all 13 COX subunits. However, we discovered recently that in primary neurons, it is Sp4 and not Sp1 that regulates some of the key glutamatergic receptor subunit genes. The question naturally arises as to the role of Sp4 in regulating COX in primary neurons. The present study utilized multiple approaches, including chromatin immunoprecipitation, promoter mutational analysis, knockdown and over-expression of Sp4, as well as functional assays to document that Sp4 indeed functionally regulate all 13 subunits of COX as well as mitochondrial transcription factors A and B. The present study discovered that among the specificity family of transcription factors, it is the less known neuron-specific Sp4 that regulates the expression of all 13 subunits of mitochondrial cytochrome c oxidase (COX) enzyme in primary neurons. Sp4 also regulates the three mitochondrial transcription factors (TFAM, TFB1M, and TFB2M) and a COX assembly protein SURF-1 in primary neurons.

  3. The Use of Cytochrome b Gene as a Specific Marker of the Rat Meat (Rattus norvegicus) on Meat and Meat Products

    OpenAIRE

    C. Sumantri; E. Andreas; Primasari, A.; H Nuraini

    2012-01-01

    Falsification of the origin of livestock meat and its processed with rat meat is a problem that must be overcome to ensure food safety. One way that is often used to detect forgeries by using cytochrome b gene as a marker. The purpose of this study was to create a specific primer derived from cytochrome b sequences in rat (Rattus norvegicus) as the DNA marker to detect any contamination of rat meat on fresh livestock meat and its processed meat products. Meatballs were made from beef meat wit...

  4. Identification of a c-Type Cytochrome Specific for Manganese Dioxide (MnO2) Reduction in Anaeromyxobacter dehalogenans Strain 2CP-C

    Science.gov (United States)

    Pfiffner, S. M.; Nissen, S.; Liu, X.; Chourey, K.; Vishnivetskaya, T. A.; Hettich, R.; Loeffler, F.

    2014-12-01

    Anaeromyxobacter dehalogenans is a metabolically versatile Deltaproteobacterium and conserves energy from the reduction of various electron acceptors, including insoluble MnO2 and ferric oxides/oxyhydroxides (FeOOH). The goal of this study was to identify c-type cytochromes involved in electron transfer to MnO2. The characterization of deletion mutants has revealed a number of c-type cytochromes involved in electron transfer to solid metal oxides in Shewanella spp. and Geobacter spp; however, a genetic system for Anaeromyxobacter is not available. The A. dehalogenans str. 2CP-C genome encodes 68 putative c-type cytochromes, which all lack functional assignments. To identify c-type cytochromes involved in electron transfer to solid MnO2, protein expression profiles of A. dehalogenans str. 2CP-C cells grown with acetate as electron donor and MnO2, ferric citrate, FeOOH, nitrate or fumarate as electron acceptors were compared. Whole cell proteomes were analyzed after trypsin proteolysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Distinct c-type cytochrome expression patterns were observed with cells grown with different electron acceptors. A. dehalogenans str. 2CP-C grown with MnO2 expressed 25 out of the 68 c-type cytochromes encoded on the genome. The c-type cytochrome Adeh_1278 was only expressed in strain 2CP-C grown with MnO2. Reverse transcription PCR confirmed that the Adeh_1278 gene was transcribed in MnO2-grown cells but not in cells grown with other terminal electron acceptors. The expression of the Adeh_1278 gene correlated with Mn(IV) reduction activity. Adeh_1278 has three heme binding motifs and is predicted to be located in the periplasm. The identification of Adeh_1278 as a protein uniquely expressed when MnO2 serves as electron acceptor suggests its utility as a biomarker for MnO2 reduction. This example demonstrates the value of the LC-MS/MS approach for identifying specific proteins of interest and making functional assignments

  5. Loss-of-function mutations of SURF-1 are specifically associated with Leigh syndrome with cytochrome c oxidase deficiency.

    Science.gov (United States)

    Tiranti, V; Jaksch, M; Hofmann, S; Galimberti, C; Hoertnagel, K; Lulli, L; Freisinger, P; Bindoff, L; Gerbitz, K D; Comi, G P; Uziel, G; Zeviani, M; Meitinger, T

    1999-08-01

    Mutations of SURF-1, a gene located on chromosome 9q34, have recently been identified in patients affected by Leigh syndrome (LS), associated with deficiency of cytochrome c oxidase (COX), the terminal component of the mitochondrial respiratory chain. To investigate to what extent SURF-1 is responsible for human disorders because of COX deficiency, we undertook sequence analysis of the SURF-1 gene in 46 unrelated patients. We analyzed 24 COX-defective patients classified as having typical Leigh syndrome (LS(COX)), 6 patients classified as Leigh-like (LL(COX)) cases, and 16 patients classified as non-LS(COX) cases. Frameshift, stop, and splice mutations of SURF-1 were detected in 18 of 24 (75%) of the LS(COX) cases. No mutations were found in the LL(COX) and non-LS(COX) group of patients. Rescue of the COX phenotype was observed in transfected cells from patients harboring SURF-1 mutations, but not in transfected cell lines from 2 patients in whom no mutations were detected by sequence analysis. Loss of function of SURF-1 protein is specifically associated with LS(COX), although a proportion of LS(COX) cases must be the result of abnormalities in genes other than SURF-1. SURF-1 is the first nuclear gene to be consistently mutated in a major category of respiratory chain defects. DNA analysis can now be used to accurately diagnose LS(COX), a common subtype of Leigh syndrome.

  6. CYP345E2, an antenna-specific cytochrome P450 from the mountain pine beetle, Dendroctonus ponderosae Hopkins, catalyses the oxidation of pine host monoterpene volatiles.

    Science.gov (United States)

    Keeling, Christopher I; Henderson, Hannah; Li, Maria; Dullat, Harpreet K; Ohnishi, Toshiyuki; Bohlmann, Jörg

    2013-12-01

    The mountain pine beetle (MPB, Dendroctonus ponderosae Hopkins) is a significant pest of western North American pine forests. This beetle responds to pheromones and host volatiles in order to mass attack and thus overcome the terpenoid chemical defences of its host. The ability of MPB antennae to rapidly process odorants is necessary to avoid odorant receptor saturation and thus the enzymes responsible for odorant clearance are an important aspect of host colonization. An antenna-specific cytochrome P450, DponCYP345E2, is the most highly expressed transcript in adult MPB antenna. In in vitro assays with recombinant enzyme, DponCYP345E2 used several pine host monoterpenes as substrates, including (+)-(3)-carene, (+)-β-pinene, (-)-β-pinene, (+)-limonene, (-)-limonene, (-)-camphene, (+)-α-pinene, (-)-α-pinene, and terpinolene. The substrates were epoxidized or hydroxylated, depending upon the substrate. To complement DponCYP345E2, we also functionally characterized the NADPH-dependent cytochrome P450 reductase and the cytochrome b5 from MPB. DponCYP345E2 is the first cytochrome P450 to be functionally characterized in insect olfaction and in MPB.

  7. Combustion derived ultrafine particles induce cytochrome P-450 expression in specific lung compartments in the developing neonatal and adult rat

    Science.gov (United States)

    Chan, Jackie K. W.; Vogel, Christoph F.; Baek, Jaeeun; Kodani, Sean D.; Uppal, Ravi S.; Bein, Keith J.; Anderson, Donald S.

    2013-01-01

    Vehicle exhaust is rich in polycyclic aromatic hydrocarbons (PAH) and can be a dominant contributor to ultrafine urban particulate matter (PM). Exposure to ultrafine PM is correlated with respiratory infections and asthmatic symptoms in young children. The lung undergoes substantial growth, alveolarization, and cellular maturation within the first years of life, which may be impacted by environmental pollutants such as PM. PAHs in PM can serve as ligands for the aryl hydrocarbon receptor (AhR) that induces expression of certain isozymes in the cytochrome P-450 superfamily, such as CYP1A1 and CYP1B1, localized in specific lung cell types. Although AhR activation and induction has been widely studied, its context within PM exposure and impact on the developing lung is poorly understood. In response, we have developed a replicable ultrafine premixed flame particle (PFP) generating system and used in vitro and in vivo models to define PM effects on AhR activation in the developing lung. We exposed 7-day neonatal and adult rats to a single 6-h PFP exposure and determined that PFPs cause significant parenchymal toxicity in neonates. PFPs contain weak AhR agonists that upregulate AhR-xenobiotic response element activity and expression and are capable inducers of CYP1A1 and CYP1B1 expression in both ages with different spatial and temporal patterns. Neonatal CYP1A1 expression was muted and delayed compared with adults, possibly because of differences in the enzyme maturation. We conclude that the inability of neonates to sufficiently adapt in response to PFP exposure may, in part, explain their susceptibility to PFP and urban ultrafine PM. PMID:23502512

  8. Human cytochrome P450 enzyme specificity for bioactivation of safrole to the proximate carcinogen 1′-hydroxysafrole

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Awad, H.M.; Boersma, M.G.; Brand, W.; Fiamegos, Y.C.; Beek, T.A. van; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2004-01-01

    In the present study, the cytochrome P450 mediated bioactivation of safrole to its proximate carcinogenic metabolite, 1′-hydroxysafrole, has been investigated for the purpose of identifying the human P450 enzymes involved. The 1′-hydroxylation of safrole was characterized in a variety of in vitro te

  9. Whole genome co-expression analysis of soybean cytochrome P450 genes identifies nodulation-specific P450 monooxygenases

    Directory of Open Access Journals (Sweden)

    Pandey Sona

    2010-11-01

    Full Text Available Abstract Background Cytochrome P450 monooxygenases (P450s catalyze oxidation of various substrates using oxygen and NAD(PH. Plant P450s are involved in the biosynthesis of primary and secondary metabolites performing diverse biological functions. The recent availability of the soybean genome sequence allows us to identify and analyze soybean putative P450s at a genome scale. Co-expression analysis using an available soybean microarray and Illumina sequencing data provides clues for functional annotation of these enzymes. This approach is based on the assumption that genes that have similar expression patterns across a set of conditions may have a functional relationship. Results We have identified a total number of 332 full-length P450 genes and 378 pseudogenes from the soybean genome. From the full-length sequences, 195 genes belong to A-type, which could be further divided into 20 families. The remaining 137 genes belong to non-A type P450s and are classified into 28 families. A total of 178 probe sets were found to correspond to P450 genes on the Affymetrix soybean array. Out of these probe sets, 108 represented single genes. Using the 28 publicly available microarray libraries that contain organ-specific information, some tissue-specific P450s were identified. Similarly, stress responsive soybean P450s were retrieved from 99 microarray soybean libraries. We also utilized Illumina transcriptome sequencing technology to analyze the expressions of all 332 soybean P450 genes. This dataset contains total RNAs isolated from nodules, roots, root tips, leaves, flowers, green pods, apical meristem, mock-inoculated and Bradyrhizobium japonicum-infected root hair cells. The tissue-specific expression patterns of these P450 genes were analyzed and the expression of a representative set of genes were confirmed by qRT-PCR. We performed the co-expression analysis on many of the 108 P450 genes on the Affymetrix arrays. First we confirmed that CYP93C5 (an

  10. Cytochrome c oxidase response to changes in cerebral oxygen delivery in the adult brain shows higher brain-specificity than haemoglobin ☆

    OpenAIRE

    Kolyva, Christina; Ghosh, Arnab; Tachtsidis, Ilias; Highton, David; Chris E Cooper; Smith, Martin; Elwell, Clare E.

    2014-01-01

    The redox state of cerebral mitochondrial cytochrome c oxidase monitored with near-infrared spectroscopy (Δ[oxCCO]) is a signal with strong potential as a non-invasive, bedside biomarker of cerebral metabolic status. We hypothesised that the higher mitochondrial density of brain compared to skin and skull would lead to evidence of brain-specificity of the Δ[oxCCO] signal when measured with a multi-distance near-infrared spectroscopy (NIRS) system. Measurements of Δ[oxCCO] as well as of concen...

  11. B-type stars in eclipsing binaries

    Science.gov (United States)

    Ratajczak, Milena; Pigulski, Andrzej

    2016-07-01

    B-type stars in eclipsing binary systems are unique astrophysical tools to test several aspects of stellar evolution. Such objects can be used e.g. to determine the masses of Beta Cephei variable stars, as well as help to place tighter constraints on the value of the convective core overshooting parameter α. Both precise photometry and high-resolution spectroscopy with high SNR are required to achieve these goals, but since many of the targets are bright enough, the challenge is fair. Following this assumption, we shall explain how we plan to examine both the aforementioned aspects of stellar evolution using observations of B-type stars obtained with a wide range of spectrographs, as well as BRITE-Constellation satellites.

  12. Role of specific cytochrome P450 isoforms in the conversion of phenoxypropoxybiguanide analogs in human liver microsomes to potent antimalarial dihydrotriazines.

    Science.gov (United States)

    Diaz, Damaris S; Kozar, Michael P; Smith, Kirsten S; Asher, Constance O; Sousa, Jason C; Schiehser, Guy A; Jacobus, David P; Milhous, Wilbur K; Skillman, Donald R; Shearer, Todd W

    2008-02-01

    Phenoxypropoxybiguanides, such as PS-15, are antimalarial prodrugs analogous to the relationship of proguanil and its active metabolite cycloguanil. Unlike cycloguanil, however, WR99210, the active metabolite of PS-15, has retained in vitro potency against newly emerging antifolate-resistant malaria parasites. Recently, in vitro metabolism of a new series of phenoxypropoxybiguanide analogs has examined the production of the active triazine metabolites by human liver microsomes. The purpose of this investigation was to elucidate the primary cytochrome P450 isoforms involved in the production of active metabolites in the current lead candidate. By using expressed human recombinant isoform preparations, specific chemical inhibitors, and isoform-specific inhibitory antibodies, the primary cytochrome P450 isoforms involved in the in vitro metabolic activation of JPC-2056 were elucidated. Unlike proguanil, which is metabolized primarily by CYP2C19, the results indicate that CYP3A4 plays a more important role in the metabolism of both PS-15 and JPC-2056. Whereas CYP2D6 appears to play a major role in the metabolism of PS-15 to WR99210, it appears less important in the conversion of JPC-2056 to JPC-2067. These results are encouraging, considering the prominence of CYP2C19 and CYP2D6 polymorphisms in certain populations at risk for contracting malaria, because the current clinical prodrug candidate from this series may be less dependent on these enzymes for metabolic activation.

  13. LmCYP4G102: An oenocyte-specific cytochrome P450 gene required for cuticular waterproofing in the migratory locust, Locusta migratoria.

    Science.gov (United States)

    Yu, Zhitao; Zhang, Xueyao; Wang, Yiwen; Moussian, Bernard; Zhu, Kun Yan; Li, Sheng; Ma, Enbo; Zhang, Jianzhen

    2016-07-22

    Cytochrome P450 superfamily proteins play important roles in detoxification of xenobiotics and during physiological and developmental processes. To contribute to our understanding of this large gene family in insects, we have investigated the function of the cytochrome P450 gene LmCYP4G102 in the migratory locust Locusta migratoria. Suppression of LmCYP4G102 expression by RNA interference (RNAi) does not interfere with moulting but causes rapid loss of body weight - probably due to massive loss of water, and death soon after moulting. Accordingly, maintaining these animals at 90% relative humidity prevented lethality. Consistently, RNAi against LmCYP4G102 provoked a decrease in the content of cuticular alkanes, which as an important fraction of cuticular hydrocarbons have been shown to confer desiccation resistance. In addition, the cuticle of LmCYP4G102-knockdown locusts was fragile and easier deformable than in control animals. Presumably, this phenotype is due to decreased amounts of cuticular water that is reported to modulate cuticle mechanics. Interestingly, LmCYP4G102 was not expressed in the epidermis that produces the cuticle but in the sub-epdiermal hepatocyte-like oenocytes. Together, our results suggest that the oenocyte-specific LmCYP4G102 plays a critical role in the synthesis of cuticular hydrocarbons, which are important for cuticle waterproofing and mechanical stability in L. migratoria.

  14. Impact of gene variants on sex-specific regulation of human Scavenger receptor class B type 1 (SR-BI expression in liver and association with lipid levels in a population-based study

    Directory of Open Access Journals (Sweden)

    Barrett-Connor Elizabeth

    2010-01-01

    Full Text Available Abstract Background Several studies have noted that genetic variants of SCARB1, a lipoprotein receptor involved in reverse cholesterol transport, are associated with serum lipid levels in a sex-dependent fashion. However, the mechanism underlying this gene by sex interaction has not been explored. Methods We utilized both epidemiological and molecular methods to study how estrogen and gene variants interact to influence SCARB1 expression and lipid levels. Interaction between 35 SCARB1 haplotype-tagged polymorphisms and endogenous estradiol levels was assessed in 498 postmenopausal Caucasian women from the population-based Rancho Bernardo Study. We further examined associated variants with overall and SCARB1 splice variant (SR-BI and SR-BII expression in 91 human liver tissues using quantitative real-time PCR. Results Several variants on a haplotype block spanning intron 11 to intron 12 of SCARB1 showed significant gene by estradiol interaction affecting serum lipid levels, the strongest for rs838895 with HDL-cholesterol (p = 9.2 × 10-4 and triglycerides (p = 1.3 × 10-3 and the triglyceride:HDL cholesterol ratio (p = 2.7 × 10-4. These same variants were associated with expression of the SR-BI isoform in a sex-specific fashion, with the strongest association found among liver tissue from 52 young women Conclusions Estrogen and SCARB1 genotype may act synergistically to regulate expression of SCARB1 isoforms and impact serum levels of HDL cholesterol and triglycerides. This work highlights the importance of considering sex-dependent effects of gene variants on serum lipid levels.

  15. Paramecium sexaurelia--intra-specific polymorphism and relationships with other Paramecium aurelia spp., revealed by cytochrome b sequence data.

    Science.gov (United States)

    Przyboś, Ewa; Barth, Dana; Berendonk, Thomas U

    2010-01-01

    Genetic distances among strains of P. sexaurelia were compared by sequencing the mitochondrial cytochrome b gene. The relationships of P. sexaurelia with representative strains of other species of the P. aurelia complex and related species, i.e., P. schewiakoffi, P. jenningsi and P. multimicronucleatum were evaluated. All investigated P. sexaurelia and P. dodecaurelia strains grouped together with high support. This P. sexaurelia/P. dodecaurelia cluster was furthermore composed of three distinct, strongly supported subgroups. Two of these groups contained both P. sexaurelia and P. dodecaurelia strains, suggesting that these species are not monophyletic. The third branch was composed of strains from Sevilla, Spain and was deeply separated (12-14% p-distance) from the other P. sexaurelia/P. dodecaurelia clades. This illustrates the urgent need for further work and more intense sampling of these "rare" species, in order to understand the status and the relationships of P. sexaurelia and P. dodecaurelia within the P. aurelia species complex. We recommend that general investigations on the speciation process be conducted within and between species of the P. aurelia complex due to the high genetic variation combined with observations that for some of the species possible cryptic speciation may have occurred. This is emphasized by data showing that for some species within this complex, species status may be less static and more dynamic than originally thought.

  16. Paucity of horizontal connections for binocular vision in V1 of naturally strabismic macaques: Cytochrome oxidase compartment specificity.

    Science.gov (United States)

    Tychsen, Lawrence; Wong, Agnes Ming-Fong; Burkhalter, Andreas

    2004-06-21

    To describe the structural basis for lack of binocular fusion in strabismic primates, we investigated intrinsic horizontal connections within striate cortex (area V1) of normal and strabismic, adult macaque monkeys. The strabismic animals had early-onset natural esotropia (the visual axes deviated nasally), normal visual acuity in each eye, and the constellation of ocular motor deficits that typify human infantile strabismus. Horizontal patchy connections and synaptic boutons were labeled by injections of the neuronal tracer biotinylated dextran amine. Ocular dominance columns (ODCs), and blob vs. interblob compartments, were revealed by using cytochrome oxidase (CO). In layers 2/3 and 4B of the strabismic monkeys, patchy projections and boutons terminated much more frequently in same-eye (73%) as opposed to opposite-eye (27%) ODCs (normal monkeys 58% and 42%, respectively). The deficiency of binocular connections in the strabismic cortex was evident qualitatively as a "skip" pattern, in which every other row of ODCs had labeled patches. Analysis of V1 in normal monkeys revealed that the deficits in strabismic V1 were due mainly to a loss of binocular connections between neurons in CO-interblob compartments. In both normal and strabismic monkeys: (1) CO-blob compartment neurons showed a more pronounced bias for monocular connectivity, and (2) commitment of connections to the same CO-compartment as the injection site (blob-to-blob, or interblob-to-interblob) was moderately strong (64%) but far from absolute. These findings help elucidate the relative roles of visual experience vs. innate mechanisms in the development of axonal connections between ocular dominance domains and compartments within macaque V1. They also provide the first detailed description of the V1 maldevelopments associated with unrepaired natural, infantile-onset strabismus in primates.

  17. In situ Raman study of redox state changes of mitochondrial cytochromes in a perfused rat heart

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Treiman, Marek; Faricelli, Barbara;

    2013-01-01

    surface of the isolated heart at normal and hypoxic conditions. Raman spectra of the heart under normal pO2 demonstrate unique peaks attributable to reduced c-and b-type cytochromes and oxymyoglobin (oMb). The cytochrome peaks decreased in intensity upon FCCP treatment, as predicted from uncoupling...

  18. Positive feedback between ethanolamine-specific phospholipid base exchange and cytochrome P450 activities in rat liver microsomes. The effect of clofibric acid.

    Science.gov (United States)

    Lenart, J; Komańska, I; Pikuła, S; Jasińska, R

    1998-08-28

    The results of the present investigation relate the effects of the nutritional state and administration of clofibric acid (CLA), a hypolipidaemic drug and peroxisomal proliferator, on phosphatidylethanolamine (PE) synthesis in rat liver and fatty acid metabolism. Fasting and CLA treatment of animals causes an increase in the amount of PE in endoplasmic reticulum (ER) membranes and mitochondria, as well as in the PE/phosphatidylcholine (PC) ratio. Moreover, the activity of the ethanolamine-specific phospholipid base exchange (PLBE) enzyme in liver ER membranes of fasted animals was enhanced by 75% in comparison to that of animals fed ad libitum. The effect of CLA treatment was additive to that of starvation; PE synthesis tested in vitro via the Ca2+-sensitive PLBE reaction increased 3-fold in comparison to rats fed ad libitum. This is confirmed by an increased Vmax for the reaction, but the affinity of the enzyme for ethanolamine was not significantly changed. These effects were accompanied by an enhanced expression of cytochrome P450 CYP4A1 isoform and elevated activity of the enzyme upon CLA administration. The stimulatory effect of CLA administration on the efficiency of the ethanolamine-specific PLBE reaction can be explained by elimination of lauric acid, a known inhibitor of de novo PE synthesis, during the course of omega-hydroxylation catalysed by CYP4A1, and by increased expression of the PLBE enzyme. The products of omega-hydroxylation of lauric acid, which are then converted by dehydrogenase to 1,12-dodecanedioic acid, did not significantly affect the in vitro synthesis of PE.

  19. Functional roles and substrate specificities of twelve cytochromes P450 belonging to CYP52 family in n-alkane assimilating yeast Yarrowia lipolytica.

    Science.gov (United States)

    Iwama, Ryo; Kobayashi, Satoshi; Ishimaru, Chiaki; Ohta, Akinori; Horiuchi, Hiroyuki; Fukuda, Ryouichi

    2016-06-01

    Yarrowia lipolytica possesses twelve ALK genes, which encode cytochromes P450 in the CYP52 family. In this study, using a Y. lipolytica strain from which all twelve ALK genes had been deleted, strains individually expressing each of the ALK genes were constructed and their roles and substrate specificities were determined by observing their growth on n-alkanes and analyzing fatty acid metabolism. The results suggested that the twelve Alk proteins can be categorized into four groups based on their substrate specificity: Alk1p, Alk2p, Alk9p, and Alk10p, which have significant activities to hydroxylate n-alkanes; Alk4p, Alk5p, and Alk7p, which have significant activities to hydroxylate the ω-terminal end of dodecanoic acid; Alk3p and Alk6p, which have significant activities to hydroxylate both n-alkanes and dodecanoic acid; and Alk8p, Alk11p, and Alk12p, which showed faint or no activities to oxidize these substrates. The involvement of Alk proteins in the oxidation of fatty alcohols and fatty aldehydes was also analyzed by measuring viability of the mutant deleted for twelve ALK genes in medium containing dodecanol and by observing growth on dodecanal of a mutant strain, in which twelve ALK genes were deleted along with four fatty aldehyde dehydrogenase genes. It was suggested that ALK gene(s) is/are involved in the detoxification of dodecanol and the assimilation of dodecanal. These results imply that genes encoding CYP52-family P450s have undergone multiplication and diversification in Y. lipolytica for assimilation of various hydrophobic compounds.

  20. Congener-specific metabolism and sequestration of dioxin-like compounds by cytochrome P450 1A induced in the liver of crows from Tokyo, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M.; Iwata, H.; Tanabe, S. [Ehime Univ., Matsuyama (Japan); Yoneda, K.; Hashimoto, T. [Japan Wildlife Research Center, Tokyo (Japan)

    2004-09-15

    Jungle crow (JC; Corvus macrorhynchos) is a useful bioindicator for monitoring contaminants in urban areas, because this species is residential, occupies a same habitat as human, and feeds variety of foods including domestic waste and garbage. Therefore, JCs may accumulate environmental contaminants such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs), which are released by human activities. Induction of cytochrome P450 (CYP) 1A is a responsive mechanism elicited by exposure to dioxinlike compounds including PCDDs/DFs and Co-PCBs. Toxicokinetic behavior of dioxin-like compounds in organisms is controlled by excretion, metabolism and absorption. These processes are, at least partly, dependent on CYP1A expression in addition to chemical structure and number of chlorine substitution of each congener. Low chlorinated congeners such as 2378-T{sub 4}CDD, 2378- T{sub 4}CDF, 12378-P{sub 5}CDD and 33'44'-PCB were easily metabolized by CYP1A1/2 in rat liver microsomes. PCDDs/DFs accumulate in hepatic tissue to a greater extent than adipose tissue in rats and mice. Recent study using transgenic CYP1A2 knockout mice demonstrated that CYP1A2 is responsible for the sequestration of 2378-T{sub 4}CDD and 23478-P{sub 5}CDF in hepatic tissue. Therefore, CYP1A is considered as a key factor responsible for toxicokinetics of dioxin-like compounds. However, there's no comprehensive data on the contribution of CYP1A to the toxicokinetics of dioxin-like congeners in wild populations. In this study, we investigated contamination levels of PCDDs/DFs and Co-PCBs in liver and breast muscle of JCs from Tokyo, Japan, and interactions of dioxin-like congeners with hepatic CYP to elucidate congener-specific toxicokinetics related to CYP expression in JC.

  1. Improved DNA barcoding method for Bemisia tabaci and related Aleyrodidae: development of universal and Bemisia tabaci biotype-specific mitochondrial cytochrome c oxidase I polymerase chain reaction primers.

    Science.gov (United States)

    Shatters, Robert G; Powell, Charles A; Boykin, Laura M; Liansheng, He; McKenzie, C L

    2009-04-01

    Whiteflies, heteropterans in the family Aleyrodidae, are globally distributed and severe agricultural pests. The mitochondrial cytochrome c oxidase I (mtCOI) sequence has been used extensively in whitefly phylogenetic comparisons and in biotype identification of the agriculturally important Bemisia tabaci (Gennadius) whitefly. Because of the economic importance of several whitefly genera, and the invasive nature of the B and the Q biotypes of Bemisia tabaci, mtCOI sequence data are continually generated from sampled populations worldwide. Routine phylogenetic comparisons and biotype identification is done through amplification and sequencing of an approximately 800-bp mtCOI DNA fragment. Despite its routine use, published primers for amplification of this region are often inefficient for some B. tabaci biotypes and especially across whitefly species. Through new sequence generation and comparison to available whitefly mtCOI sequence data, a set of polymerase chain reaction (PCR) amplification primers (Btab-Uni primers) were identified that are more efficient at amplifying approximately 748 bp of the approximately 800-bp fragment currently used. These universal primers amplify an mtCOI fragment from numerous B. tabaci biotypes and whitefly genera by using a single amplification profile. Furthermore, mtCOI PCR primers specific for the B, Q, and New World biotypes of B. tabaci were designed that allow rapid discrimination among these biotypes. These primers produce a 478-, 405-, and 303-bp mtCOI fragment for the B, New World, and Q biotypes, respectively. By combining these primers and using rapid PCR and electrophoretic techniques, biotype determination can be made within 3 h for up to 96 samples at a time.

  2. B-type natriuretic peptide secretion following scuba diving

    DEFF Research Database (Denmark)

    Passino, Claudio; Franzino, Enrico; Giannoni, Alberto;

    2011-01-01

    To examine the neurohormonal effects of a scuba dive, focusing on the acute changes in the plasma concentrations of the different peptide fragments from the B-type natriuretic peptide (BNP) precursor....

  3. Exon-specific northern analysis and rapid amplification of cDNA ends (RACE) reveal that the proximal promoter II (PII) is responsible for aromatase cytochrome P450 (CYP19) expression in human ovary.

    Science.gov (United States)

    Jenkins, C; Michael, D; Mahendroo, M; Simpson, E

    1993-11-01

    Estrogens are synthesized from C19 steroids by a unique form of cytochrome P450, aromatase cytochrome P-450 (P-450AROM; the product of the CYP19 gene). We have shown that tissue-specific expression of human P-450AROM is determined, in part, by the use of alternative promoters. Previous methods of analysis for determining the specific 5'-termini of the different transcripts included S1 nuclease protection, primer extension, and Northern analysis. In the present study we have used the RACE procedure (rapid amplification of cDNA ends) to amplify and clone the 5' termini of P-450AROM transcripts expressed in human corpus luteum (CL). Sequencing of the resulting clones supports the results of the previously performed studies. Specifically, the proximal promoter, PII, is the predominant promoter utilized in CL, such that the start of transcription occurs 26 bp downstream of the putative TATA sequence. A minority of the clones possess an alternative 5'-end, namely I.3. Exon-specific Northern analysis confirms that the majority of the P-450AROM transcripts in CL tissue contain sequence specific for promoter II. Similarly, exon-specific Northern analysis indicates that transcripts in human follicles, as well as granulosa cells in culture, contain primarily sequence specific for promoter II.

  4. Sensibilidade e especificidade do hormônio natriurético do tipo B para identificar doentes com insuficiência mitral grave sintomáticos e assintomáticos Sensitivity and specificity of B-type natriuretic peptide for identifying symptomatic and asymptomatic patients with severe mitral regurgitation

    Directory of Open Access Journals (Sweden)

    Zilda Machado Meneghelo

    2004-12-01

    Full Text Available OBJETIVO: Verificar a sensibilidade e a especificidade do hormônio natriurético do tipo B (BNP para identificar pacientes ambulatoriais, com insuficiência mitral crônica grave, sintomáticos e assintomáticos. MÉTODOS: Um grupo de pacientes com insuficiência mitral foi examinado e submetido à eletrocardiografia, telerradiografia de tórax, coletas de sangue venoso e ecocardiograma transtorácico. Por meio da análise de variáveis ecocardiográficas, 62 pacientes apresentavam refluxo mitral discreto e moderado (G I e 34 refluxo mitral grave (G II. A capacidade discriminante do BNP em detectar pacientes com insuficiência mitral grave foi avaliada pela construção de curvas ROC. RESULTADOS: Entre os 96 doentes, 71 (73% eram mulheres e as idades variaram entre 15 e 63 (média de 31,7 anos. Os valores de BNP variaram de 0,00 pg/ml a 193 pg/ml. Os doentes do G I tiveram um valor médio de BNP de 18,10 ± 0,74 pg/ml e os do G II de 50,54 ± 1,46 pg/ml, (p=0,001. O valor de corte para identificar insuficiência mitral grave foi de 15,40 pg/ml, para o melhor balanço entre a sensibilidade e a especificidade, respectivamente de 0,73 e 0,74. O valor de corte para identificar pacientes sintomáticos e com insuficiência mitral grave foi de 28,40 pg/ml, para o melhor balanço entre a sensibilidade e a especificidade, respectivamente de 0,78 e 0,83. CONCLUSÃO: Os valores de BNP capazes de indentificar doentes com insuficiência mitral grave assintomáticos e sintomáticos são menores do que os 100 pg/ml considerados para o diagnóstico de insuficiência cardíaca.OBJECTIVE: To assess the sensitivity and specificity of B-type natriuretic peptide (BNP for identifying symptomatic and asymptomatic patients with severe chronic mitral regurgitation followed up on an outpatient care basis. METHODS: A group of patients with mitral regurgitation underwent electrocardiography, chest teleradiography, venous blood withdrawal, and transthoracic

  5. Rapid detection and identification of Candida albicans and Torulopsis (Candida) glabrata in clinical specimens by species-specific nested PCR amplification of a cytochrome P-450 lanosterol-alpha-demethylase (L1A1) gene fragment.

    Science.gov (United States)

    Burgener-Kairuz, P; Zuber, J P; Jaunin, P; Buchman, T G; Bille, J; Rossier, M

    1994-08-01

    PCR of a Candida albicans cytochrome P-450 lanosterol-alpha-demethylase (P450-L1A1) gene segment is a rapid and sensitive method of detection in clinical specimens. This enzyme is a target for azole antifungal action. In order to directly detect and identify the clinically most important species of Candida, we cloned and sequenced 1.3-kbp fragments of the cytochrome P450-L1A1 genes from Torulopsis (Candida) glabrata and from Candida krusei. These segments were compared with the published sequences from C. albicans and Candida tropicalis. Amplimers for gene sequences highly conserved throughout the fungal kingdom were first used; positive PCR results were obtained for C. albicans, T. glabrata, C. krusei, Candida parapsilosis, C. tropicalis, Cryptococcus neoformans, and Trichosporon beigelii DNA extracts. Primers were then selected for a highly variable region of the gene, allowing the species-specific detection from purified DNA of C. albicans, T. glabrata, C. krusei, and C. tropicalis. The assay sensitivity as tested for C. albicans in seeded clinical specimens such as blood, peritoneal fluid, or urine was 10 to 20 cells per 0.1 ml. Compared with results obtained by culture, the sensitivity, specificity, and efficiency of the species-specific nested PCR tested with 80 clinical specimens were 71, 95, and 83% for C. albicans and 100, 97, and 98% for T. glabrata, respectively.

  6. B-type natriuretic peptides and mortality after stroke

    DEFF Research Database (Denmark)

    García-Berrocoso, Teresa; Giralt, Dolors; Bustamante, Alejandro;

    2013-01-01

    To measure the association of B-type natriuretic peptide (BNP) and N-terminal fragment of BNP (NT-proBNP) with all-cause mortality after stroke, and to evaluate the additional predictive value of BNP/NT-proBNP over clinical information....

  7. Low prevalence of B-type natriuretic peptide levels

    NARCIS (Netherlands)

    Hogenhuis, J; Voors, AA; Jaarsma, T; Hillege, HL; Hoes, AW; van Veldhuisen, DJ

    2006-01-01

    Background In patients with acute heart failure (HF) presenting at the emergency department, a B-type natriuretic peptide (BNP) level <100 pg/mL was found in only 10% of the patients. However, in a more stable outpatient HF population from another study, a BNP level <100 pg/mL was found in as many a

  8. Cytochrome P450 expression in mouse brain: specific isoenzymes involved in Phase I metabolizing system of porphyrinogenic agents in both microsomes and mitochondria.

    Science.gov (United States)

    Lavandera, Jimena; Ruspini, Silvina; Batlle, Alcira; Buzaleh, Ana María

    2015-02-01

    Brain cytochrome P450 (CYP) metabolizes a variety of drugs to produce their pharmacological effects within the brain. We have previously observed that porphyrinogenic agents altered CYP levels in brain. The aim of this work was to further study the involvement of mice brain mitochondrial and microsomal Phase I drug metabolizing system when porphyrinogenic agents, such as Enflurane, Isoflurane, allylisopropylacetamide, veronal, ethanol, and Griseofulvin were administered. To this end, CYP2E1, CYP2B1, and CYP3A4 expression were measured. NADPH cytochrome P450 reductase (CPR) expression was also determined. Western Blots were performed in microsomes and mitochondria of whole brain. Some of the drugs studied altered expression mainly in microsomes. Chronic Isoflurane augmented mitochondrial isoform, although this anaesthetic diminished microsomal expression. Ethanol and topical Griseofulvin affected expression in microsomes but not in mitochondria. CYP2E1 mitochondrial activity was induced by acute Enflurane; while the activity of the microsomal protein was enhanced in alcoholised animals. Ethanol also induced CYP2E1 expression in microsomes, although Isoflurane provoked opposite effects in mitochondria and microsomes. Expression of CPR was also induced. Several reports support an emergent role of CYP enzymes in the pathogenesis of neurological disorders, so CYP response in brain could be one of the multiples factors influencing porphyria acute attacks.

  9. Levels of hexabromocyclododecane in harbor porpoises and common dolphins from western European seas, with evidence for stereoisomer-specific biotransformation by cytochrome p450.

    Science.gov (United States)

    Zegers, Bart N; Mets, Anchelique; Van Bommel, Ronald; Minkenberg, Chris; Hamers, Timo; Kamstra, Jorke H; Pierce, Graham J; Boon, Jan P

    2005-04-01

    Commercial hexabromocyclododecane (HBCD) is a high-production-volume flame-retardant applied in polystyrene foams. It contains three stereoisomers, of which gamma-HBCD always dominates. Here we report on the levels of HBCD in blubber of harbor porpoise and common dolphin from different European seas. The highest total (sigma)-HBCD levels were measured in harbor porpoises stranded on the Irish and Scottish coasts of the Irish Sea (median concentration 2.9 microg (g of lipid)(-1)) and the northwest coast of Scotland (median concentration 5.1 microg (g of lipid)(-1)). The median levels in other areas were, for the harbor porpoise south coast of Ireland, 1.2 microg (g of lipid)(-1), for the coasts of The Netherlands, Belgium, and France north of Calais (southern North Sea), 1.1 microg (g of lipid)(-1), for the east coast of Scotland (northern North Sea), 0.77 microg (g of lipid)(-1), and, for Galicia (Spain), 0.1 microg (g of lipid)(-1). The median levels for the common dolphin were, for west coast of Ireland, 0.9 microg (g of lipid)(-1), for the French coast of the English Channel between Normandy and Brest, 0.4 microg (g of lipid)(-1), and, for Galicia, 0.2 microg (g of lipid)(-1). A subset of 10 harbor porpoise and 9 common dolphin blubber samples representing all areas were analyzed by LC/MS to determine the diastereomeric composition of their HBCD residues. All samples showed exclusively the peak of alpha-HBCD. To test if biotransformation by the cytochrome P450 system could explain the observed compositional difference with technical HBCD mixtures, a number of in vitro assays with microsomal preparations of liver were carried out. We had to revert to material stored at -80 degrees C from laboratory rats and a fresh harbor seal found dead in the Dutch Wadden Sea, since such liver samples of cetaceans were not in our possession. The in vitro assays showed that beta- and gamma-HBCDs were indeed significantly metabolized when incubated in the presence of NADPH as

  10. Functional relationship of the cytochrome b to the superoxide-generating oxidase of human neutrophils.

    Science.gov (United States)

    Gabig, T G; Schervish, E W; Santinga, J T

    1982-04-25

    A subcellular particulate fraction containing the NADPH-dependent O2.--generating oxidase from stimulated human neutrophils was prepared. This fraction was depleted of certain enzyme markers of primary and secondary granules and was devoid of measurable myeloperoxidase, both enzymatically and spectrally. When prepared from neutrophils which had been previously stimulated with phorbal myristate acetate, this fraction contained cyanide-insensitive, pyridine nucleotide-dependent O2.--generating activity with a specific activity of 260 nmol min-1 mg-1. O2.--generating activity is completely ablated by p-chloromercuribenzoate exposure. Preparations from normal unstimulated neutrophils or stimulated neutrophils from a male patient with chronic granulomatous disease had negligible amounts of this O2.--generating enzymatic activity. The dominant chromophore in this preparation was a b-type cytochrome, the spectral and functional characteristics of which are further described herein. Pyridine nucleotide-dependent reduction of the intrinsic cytochrome b closely parallels O2.- generation in this preparation. Specifically, reduction occurs in preparations from phorbal myristate acetate-stimulated neutrophils and is absent in unstimulated or stimulated p-chloromercuribenzoate-inactivated preparations.

  11. Similar substrate specificity of cynomolgus monkey cytochrome P450 2C19 to reported human P450 2C counterpart enzymes by evaluation of 89 drug clearances.

    Science.gov (United States)

    Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

    2015-12-01

    Cynomolgus monkeys are used widely in preclinical studies as non-human primate species. The amino acid sequence of cynomolgus monkey cytochrome P450 (P450 or CYP) 2C19 is reportedly highly correlated to that of human CYP2C19 (92%) and CYP2C9 (93%). In the present study, 89 commercially available compounds were screened to find potential substrates for cynomolgus monkey CYP2C19. Of 89 drugs, 34 were metabolically depleted by cynomolgus monkey CYP2C19 with relatively high rates. Among them, 30 compounds have been reported as substrates or inhibitors of, either or both, human CYP2C19 and CYP2C9. Several compounds, including loratadine, showed high selectivity to cynomolgus monkey CYP2C19, and all of these have been reported as human CYP2C19 and/or CYP2C9 substrates. In addition, cynomolgus monkey CYP2C19 formed the same loratadine metabolite as human CYP2C19, descarboethoxyloratadine. These results suggest that cynomolgus monkey CYP2C19 is generally similar to human CYP2C19 and CYP2C9 in its substrate recognition functionality.

  12. Nitrogen-doped graphene quantum dots-labeled epitope imprinted polymer with double templates via the metal chelation for specific recognition of cytochrome c.

    Science.gov (United States)

    Yan, Yun-Jing; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

    2017-05-15

    A novel fluorescent sensor nitrogen-doped graphene quantum dots (N-GQDs)/SiO2/molecular imprinting polymer(N-GQDs/SiO2/MIP)was fabricated by surface imprinting and epitope imprinting to recognize and detect the target protein cytochrome c (Cyt C) with fluorescence quenching. In the polymerization process, the C- and N-terminal nonapeptides of Cyt C were selected as the double templates which were fixed by functional monomer (zinc acrylate) through metal chelation and steady six-membered ring. The linear range of fluorescence quenching for this receptor towards Cyt C was 0.20-60μM, and the detection limit was 0.11μM. The precision for six times replicate determination of Cyt C at 30μM was 1.20%, and the imprinting factor (IF) was 3.06. The recoveries of the material to Cyt C in urine were 99.3-114.0%. In brief, this work proposed a strategy to prepare a new type fluorescent imprinting polymer based on N-GQDs and provided an attractive perspective for the detection of protein by using the combination of N-GQDs and molecular imprinting technique.

  13. Atrial secretion of B-type natriuretic peptide

    DEFF Research Database (Denmark)

    Goetze, Jens Peter; Friis-Hansen, Lennart; Rehfeld, Jens F;

    2006-01-01

    In the normal heart, the endocrine capacity resides in the atria. Atrial myocytes express and secrete natriuretic hormones that regulate fluid homeostasis and blood pressure. But in ventricular disease, atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) gene expression is also...... activated in ventricular myocytes. Plasma concentrations of natriuretic peptides and their biosynthetic precursors are accordingly increased in patients with marked ventricular dysfunction. In contrast, atrial peptide secretion in ventricular disease has received less attention, and our present...... are also active in heart failure. Plasma measurement of cardiac natriuretic peptides and their molecular precursors can perhaps help us to discriminate when, where and how....

  14. Liver-specific cytochrome P450 CYP2C22 is a direct target of retinoic acid and a retinoic acid-metabolizing enzyme in rat liver.

    Science.gov (United States)

    Qian, Linxi; Zolfaghari, Reza; Ross, A Catharine

    2010-07-01

    Several cytochrome P450 (CYP) enzymes catalyze the C4-hydroxylation of retinoic acid (RA), a potent inducer of cell differentiation and an agent in the treatment of several diseases. Here, we have characterized CYP2C22, a member of the rat CYP2C family with homology to human CYP2C8 and CYP2C9. CYP2C22 was expressed nearly exclusively in hepatocytes, where it was one of the more abundant mRNAs transcripts. In H-4-II-E rat hepatoma cells, CYP2C22 mRNA was upregulated by all-trans (at)-RA, and Am580, a nonmetabolizable analog of at-RA. In comparison, in primary human hepatocytes, at-RA increased CYP2C9 but not CYP2C8 mRNA. Analysis of the CYP2C22 promoter region revealed a RA response element (5'-GGTTCA-(n)5-AGGTCA-3') in the distal flanking region, which bound the nuclear hormone receptors RAR and RXR and which was required for transcriptional activation response of this promoter to RA in CYP2C22-luciferase-transfected RA-treated HepG2 cells. The cDNA-expressed CYP2C22 protein metabolized [3H]at-RA to more polar metabolites. While long-chain polyunsaturated fatty acids competed, 9-cis-RA was a stronger competitor. Our studies demonstrate that CYP2C22 is a high-abundance, retinoid-inducible, hepatic P450 with the potential to metabolize at-RA, providing additional insight into the role of the CYP2C gene family in retinoid homeostasis.

  15. Gomisin A is a Novel Isoform-Specific Probe for the Selective Sensing of Human Cytochrome P450 3A4 in Liver Microsomes and Living Cells.

    Science.gov (United States)

    Wu, Jing-Jing; Ge, Guang-Bo; He, Yu-Qi; Wang, Ping; Dai, Zi-Ru; Ning, Jing; Hu, Liang-Hai; Yang, Ling

    2016-01-01

    Nearly half of prescription medicines are metabolized by human cytochrome P450 (CYP) 3A. CYP3A4 and 3A5 are two major isoforms of human CYP3A and share most of the substrate spectrum. A very limited previous study distinguished the activity of CYP3A4 and CYP3A5, identifying the challenge in predicting CYP3A-mediated drug clearance and drug-drug interaction. In the present study, we introduced gomisin A (GA) with a dibenzocyclooctadiene skeleton as a novel selective probe of CYP3A4. The major metabolite of GA was fully characterized as 8-hydroxylated GA by LC-MS and NMR. CYP3A4 was assigned as the predominant isozyme involved in GA 8-hydroxylation by reaction phenotyping assays, chemical inhibition assays, and correlation studies. GA 8-hydroxylation in both recombinant human CYP3A4 and human liver microsomes followed classic Michaelis-Menten kinetics. The intrinsic clearance values indicated that CYP3A4 contributed 12.8-fold more than CYP3A5 to GA 8-hydroxylation. Molecular docking studies indicated different hydrogen bonds and π-π interactions between CYP3A4 and CYP3A5, which might result in the different catalytic activity for GA 8-hydroxylation. Furthermore, GA exhibited a stronger inhibitory activity towards CYP3A4 than CYP3A5, which further suggested a preferred selectivity of CYP3A4 for the transformation of GA. More importantly, GA has been successfully applied to selectively monitor the modulation of CYP3A4 activities by the inducer rifampin in hepG2 cells, which is consistent with the level change of CYP3A4 mRNA expression. In summary, our results suggested that GA could be used as a novel probe for the selective sensing of CYP3A4 in tissue and cell preparations.

  16. Molecular Organization of Cytochrome c 2 near the Binding Domain of Cytochrome bc 1 Studied by Electron Spin–Lattice Relaxation Enhancement

    OpenAIRE

    Pietras, Rafał; Sarewicz, Marcin; Osyczka, Artur

    2014-01-01

    Measurements of specific interactions between proteins are challenging. In redox systems, interactions involve surfaces near the attachment sites of cofactors engaged in interprotein electron transfer (ET). Here we analyzed binding of cytochrome c 2 to cytochrome bc 1 by measuring paramagnetic relaxation enhancement (PRE) of spin label (SL) attached to cytochrome c 2. PRE was exclusively induced by the iron atom of heme c 1 of cytochrome bc 1, which guaranteed that only the configurations wit...

  17. Biogenesis of cytochrome b6 in photosynthetic membranes.

    Science.gov (United States)

    Saint-Marcoux, Denis; Wollman, Francis-André; de Vitry, Catherine

    2009-06-29

    In chloroplasts, binding of a c'-heme to cytochrome b(6) on the stromal side of the thylakoid membranes requires a specific mechanism distinct from the one at work for c-heme binding to cytochromes f and c(6) on the lumenal side of membranes. Here, we show that the major protein components of this pathway, the CCBs, are bona fide transmembrane proteins. We demonstrate their association in a series of hetero-oligomeric complexes, some of which interact transiently with cytochrome b(6) in the process of heme delivery to the apoprotein. In addition, we provide preliminary evidence for functional assembly of cytochrome b(6)f complexes even in the absence of c'-heme binding to cytochrome b(6). Finally, we present a sequential model for apo- to holo-cytochrome b(6) maturation integrated within the assembly pathway of b(6)f complexes in the thylakoid membranes.

  18. The elusive third subunit IIa of the bacterial B-type oxidases: the enzyme from the hyperthermophile Aquifex aeolicus.

    Directory of Open Access Journals (Sweden)

    Laurence Prunetti

    Full Text Available The reduction of molecular oxygen to water is catalyzed by complicated membrane-bound metallo-enzymes containing variable numbers of subunits, called cytochrome c oxidases or quinol oxidases. We previously described the cytochrome c oxidase II from the hyperthermophilic bacterium Aquifex aeolicus as a ba(3-type two-subunit (subunits I and II enzyme and showed that it is included in a supercomplex involved in the sulfide-oxygen respiration pathway. It belongs to the B-family of the heme-copper oxidases, enzymes that are far less studied than the ones from family A. Here, we describe the presence in this enzyme of an additional transmembrane helix "subunit IIa", which is composed of 41 amino acid residues with a measured molecular mass of 5105 Da. Moreover, we show that subunit II, as expected, is in fact longer than the originally annotated protein (from the genome and contains a transmembrane domain. Using Aquifex aeolicus genomic sequence analyses, N-terminal sequencing, peptide mass fingerprinting and mass spectrometry analysis on entire subunits, we conclude that the B-type enzyme from this bacterium is a three-subunit complex. It is composed of subunit I (encoded by coxA(2 of 59000 Da, subunit II (encoded by coxB(2 of 16700 Da and subunit IIa which contain 12, 1 and 1 transmembrane helices respectively. A structural model indicates that the structural organization of the complex strongly resembles that of the ba(3 cytochrome c oxidase from the bacterium Thermus thermophilus, the IIa helical subunit being structurally the lacking N-terminal transmembrane helix of subunit II present in the A-type oxidases. Analysis of the genomic context of genes encoding oxidases indicates that this third subunit is present in many of the bacterial oxidases from B-family, enzymes that have been described as two-subunit complexes.

  19. 21 CFR 862.1117 - B-type natriuretic peptide test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false B-type natriuretic peptide test system. 862.1117... Systems § 862.1117 B-type natriuretic peptide test system. (a) Identification. The B-type natriuretic peptide (BNP) test system is an in vitro diagnostic device intended to measure BNP in whole blood...

  20. Molecular organization of cytochrome c2 near the binding domain of cytochrome bc1 studied by electron spin-lattice relaxation enhancement.

    Science.gov (United States)

    Pietras, Rafał; Sarewicz, Marcin; Osyczka, Artur

    2014-06-19

    Measurements of specific interactions between proteins are challenging. In redox systems, interactions involve surfaces near the attachment sites of cofactors engaged in interprotein electron transfer (ET). Here we analyzed binding of cytochrome c2 to cytochrome bc1 by measuring paramagnetic relaxation enhancement (PRE) of spin label (SL) attached to cytochrome c2. PRE was exclusively induced by the iron atom of heme c1 of cytochrome bc1, which guaranteed that only the configurations with SL to heme c1 distances up to ∼30 Å were detected. Changes in PRE were used to qualitatively and quantitatively characterize the binding. Our data suggest that at low ionic strength and under an excess of cytochrome c2 over cytochrome bc1, several cytochrome c2 molecules gather near the binding domain forming a "cloud" of molecules. When the cytochrome bc1 concentration increases, the cloud disperses to populate additional available binding domains. An increase in ionic strength weakens the attractive forces and the average distance between cytochrome c2 and cytochrome bc1 increases. The spatial arrangement of the protein complex at various ionic strengths is different. Above 150 mM NaCl the lifetime of the complexes becomes so short that they are undetectable. All together the results indicate that cytochrome c2 molecules, over the range of salt concentration encompassing physiological ionic strength, do not form stable, long-lived complexes but rather constantly collide with the surface of cytochrome bc1 and ET takes place coincidentally with one of these collisions.

  1. Kepler observations of the variability in B-type stars

    DEFF Research Database (Denmark)

    Balona, Luis A.; Pigulski, A.; De Cat, P.

    2011-01-01

    variations in other stars which we attribute to proximity effects in binary systems or possibly rotational modulation. We find no evidence for pulsating stars between the cool edge of the SPB and the hot edge of the δ Sct instability strips. None of the stars shows the broad features which can be attributed......The analysis of the light curves of 48 B-type stars observed by Kepler is presented. Among these are 15 pulsating stars, all of which show low frequencies, characteristic of slowly pulsating B (SPB) stars. Seven of these stars also show a few weak, isolated high frequencies and they could...... be considered as SPB/β Cephei (β Cep) hybrids. In all cases, the frequency spectra are quite different from what is seen from ground-based observations. We suggest that this is because most of the low frequencies are modes of high degree which are predicted to be unstable in models of mid-B stars. We find...

  2. Isolation and extreme sex-specific expression of cytochrome P450 genes in the bark beetle, Ips paraconfusus, following feeding on the phloem of host ponderosa pine, Pinus ponderosa.

    Science.gov (United States)

    Huber, D P W; Erickson, M L; Leutenegger, C M; Bohlmann, J; Seybold, S J

    2007-06-01

    We have identified cDNAs and characterized the expression of 13 novel cytochrome P450 genes of potential importance in host colonization and reproduction by the California fivespined ips, Ips paraconfusus. Twelve are of the Cyp4 family and one is of the Cyp9 family. Following feeding on host Pinus ponderosa phloem, bark beetle transcript levels of several of the Cyp4 genes increased or decreased in males only or in both sexes. In one instance (IparaCyp4A5) transcript accumulated significantly in females, but declined significantly in males. The Cyp9 gene (Cyp9T1) transcript levels in males were > 85 000 x higher at 8 h and > 25 000 x higher at 24 h after feeding compared with nonfed controls. Transcript levels in females were approximately 150 x higher at 24 h compared with nonfed controls. Cyp4G27 transcript was present constitutively regardless of sex or feeding and served as a better housekeeping gene than beta-actin or 18S rRNA for the real-time TaqMan polymerase chain reaction analysis. The expression patterns of Cyp4AY1, Cyp4BG1, and, especially, Cyp9T1 in males suggest roles for these genes in male-specific aggregation pheromone production. The differential transcript accumulation patterns of these bark beetle P450s provide insight into ecological interactions of I. paraconfusus with its host pines.

  3. Fundamental properties of nearby single early B-type stars

    Science.gov (United States)

    Nieva, María-Fernanda; Przybilla, Norbert

    2014-06-01

    Aims: Fundamental parameters of a sample of 26 apparently slowly-rotating single early B-type stars in OB associations and in the field within a distance of ≲400 pc from the Sun are presented and compared to high-precision data from detached eclipsing binaries (DEBs). Together with surface abundances for light elements the data are used to discuss the evolutionary status of the stars in context of the most recent Geneva grid of models for core hydrogen-burning stars in the mass-range ~6 to 18 M⊙ at metallicity Z = 0.014. Methods: The fundamental parameters are derived on the basis of accurate and precise atmospheric parameters determined earlier by us from non-LTE analyses of high-quality spectra of the sample stars, utilising the new Geneva stellar evolution models. Results: Evolutionary masses plus radii and luminosities are determined to better than typically 5%, 10%, and 20% uncertainty, respectively, facilitating the mass-radius and mass-luminosity relationships to be recovered for single core hydrogen-burning objects with a similar precision as derived from DEBs. Good agreement between evolutionary and spectroscopic masses is found. Absolute visual and bolometric magnitudes are derived to typically ~0.15-0.20 mag uncertainty. Metallicities are constrained to better than 15-20% uncertainty and tight constraints on evolutionary ages of the stars are provided. Overall, the spectroscopic distances and ages of individual sample stars agree with independently derived values for the host OB associations. Signatures of mixing with CN-cycled material are found in 1/3 of the sample stars. Typically, these are consistent with the amount predicted by the new Geneva models with rotation. The presence of magnetic fields appears to augment the mixing efficiency. In addition, a few objects are possibly the product of binary evolution. In particular, the unusual characteristics of τ Sco point to a blue straggler nature, due to a binary merger. Conclusions: The accuracy

  4. Differences in hepatic cytochrome P450 activity correlate with the strain-specific biotransformation of medetomidine in AX/JU and IIIVO/JU inbred rabbits.

    Science.gov (United States)

    Avsaroglu, H; Bull, S; Maas-Bakker, R F; Scherpenisse, P; Van Lith, H A; Bergwerff, A A; Hellebrekers, L J; Van Zutphen, L F M; Fink-Gremmels, J

    2008-08-01

    Medetomidine is an alpha(2)-adrenoceptor agonist with sedative and analgesic properties. Previously we demonstrated significant differences in the response to medetomidine between two inbred rabbit strains, denoted IIIVO/JU and AX/JU. The aim of the present study was twofold: first, to compare the hepatic CYP450 enzyme activities between these rabbit strains [n = 13(male male,7 female female)/strain]. To this end, liver microsomes were incubated with known fluorescent substrates for the major drug-metabolizing CYP450 isoforms. A comparison of the obtained results indicated significant gender differences as well as differences between the two rabbit inbred strains. Secondly, the biotransformation rate of medetomidine in liver microsomes of both rabbit strains was determined using liquid chromatography coupled to tandem mass spectrometry. The rate of hydroxymedetomidine and medetomidine carboxylic acid formation was found to be significantly higher in the AX/JU strain. Specific CYP2D and CYP2E inhibitors could decrease the formation of both metabolites. Significant correlations were found between the rate of biotransformation of medetomidine and the activities of CYP2D and CYP2E, as well as between CYP450 enzyme activities and the anaesthetic response to medetomidine.

  5. The mechanism by which oxygen and cytochrome c increase the rate of electron transfer from cytochrome a to cytochrome a3 of cytochrome c oxidase.

    Science.gov (United States)

    Bickar, D; Turrens, J F; Lehninger, A L

    1986-11-05

    When cytochrome c oxidase is isolated from mitochondria, the purified enzyme requires both cytochrome c and O2 to achieve its maximum rate of internal electron transfer from cytochrome a to cytochrome a3. When reductants other than cytochrome c are used, the rate of internal electron transfer is very slow. In this paper we offer an explanation for the slow reduction of cytochrome a3 when reductants other than cytochrome c are used and for the apparent allosteric effects of cytochrome c and O2. Our model is based on the conventional understanding of cytochrome oxidase mechanism (i.e. electron transfer from cytochrome a/CuA to cytochrome a3/CuB), but assumes a relatively rapid two-electron transfer between cytochrome a/CuA and cytochrome a3/CuB and a thermodynamic equilibrium in the "resting" enzyme (the enzyme as isolated) which favors reduced cytochrome a and oxidized cytochrome a3. Using the kinetic constants that are known for this reaction, we find that the activating effects of O2 and cytochrome c on the rate of electron transfer from cytochrome a to cytochrome a3 conform to the predictions of the model and so provide no evidence of any allosteric effects or control of cytochrome c oxidase by O2 or cytochrome c.

  6. Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase.

    Science.gov (United States)

    Pastorino, Laura; Dellacasa, Elena; Noor, Mohamed R; Soulimane, Tewfik; Bianchini, Paolo; D'Autilia, Francesca; Antipov, Alexei; Diaspro, Alberto; Tofail, Syed A M; Ruggiero, Carmelina

    2014-01-01

    Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties.

  7. Multilayered polyelectrolyte microcapsules: interaction with the enzyme cytochrome C oxidase.

    Directory of Open Access Journals (Sweden)

    Laura Pastorino

    Full Text Available Cell-sized polyelectrolyte capsules functionalized with a redox-driven proton pump protein were assembled for the first time. The interaction of polyelectrolyte microcapsules, fabricated by electrostatic layer-by-layer assembly, with cytochrome c oxidase molecules was investigated. We found that the cytochrome c oxidase retained its functionality, that the functionalized microcapsules interacting with cytochrome c oxidase were permeable and that the permeability characteristics of the microcapsule shell depend on the shell components. This work provides a significant input towards the fabrication of an integrated device made of biological components and based on specific biomolecular functions and properties.

  8. Functional coadaptation between cytochrome c and cytochrome c oxidase within allopatric populations of a marine copepod.

    Science.gov (United States)

    Rawson, Paul D; Burton, Ronald S

    2002-10-01

    Geographically isolated populations may accumulate alleles that function well on their own genetic backgrounds but poorly on the genetic backgrounds of other populations. Consequently, interpopulation hybridization may produce offspring of low fitness as a result of incompatibilities arising in allopatry. Genes participating in these epistatic incompatibility systems remain largely unknown. In fact, despite the widely recognized importance of epistatic interactions among gene products, few data directly address the functional consequences of such interactions among natural genetic variants. In the marine copepod, Tigriopus californicus, we found that the cytochrome c variants isolated from two different populations each had significantly higher activity with the cytochrome c oxidase derived from their respective source population. Three amino acid substitutions in the cytochrome c protein appear to be sufficient to confer population specificity. These results suggest that electron transport system (ETS) proteins form coadapted sets of alleles within populations and that disruption of the coadapted ETS gene complex leads to functional incompatibilities that may lower hybrid fitness.

  9. N-terminal Pro-B-type natriuretic peptide: a measure of significant patent cuctus arteriosus

    LENUS (Irish Health Repository)

    OFarombi-Oghuvbu, IO

    2008-01-24

    Background: B type natriuretic peptide (BNP) is a marker for ventricular dysfunction secreted as a pre-prohormone, Pro-B-type natriuretic peptide (ProBNP), and cleaved into BNP and a biologically inactive fragment, N-terminal pro-B-type natriuretic peptide (NT-proBNP). Little is known about the clinical usefulness of NT-proBNP in preterm infants.\\r\

  10. Calcium transport in vesicles energized by cytochrome oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Rosier, Randy N.

    1979-01-01

    Experiments on the reconstitution of cytochrome oxidase into phospholipid vesicles were carried out using techniques of selectivity energizing the suspensions with ascorbate and cytochrome c or ascorbate, PMS, and internally trapped cytochrome c. It was found that the K/sup +/ selective ionophore valinomycin stimulated the rate of respiration of cytochrome oxidase vesicles regardless of the direction of the K/sup +/ flux across the vesicle membranes. The stimulation occurred in the presence of protonophoric uncouplers and in the complete absence of potassium or in detergent-lysed suspensions. Gramicidin had similar effects and it was determined that the ionophores acted by specific interaction with cytochrome oxidase rather than by the previously assumed collapse of membrane potentials. When hydrophobic proteins and appropriate coupling factors were incorporated into the cytochrome oxidase, vesicles phosphorylation of ADP could be coupled to the oxidation reaction of cytochrome oxidase. Relatively low P:O, representing poor coupling of the system, were problematical and precluded measurements of protonmotive force. However the system was used to study ion translocation.

  11. Identification of cytochrome P450 enzymes critical for lung tumorigenesis by the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK): insights from a novel Cyp2abfgs-null mouse.

    Science.gov (United States)

    Li, Lei; Megaraj, Vandana; Wei, Yuan; Ding, Xinxin

    2014-11-01

    Cytochrome P450 (P450) enzymes encoded by the mouse Cyp2abfgs gene cluster are preferentially expressed in the respiratory tract. Previous studies have demonstrated that pulmonary P450-mediated bioactivation is necessary for lung tumorigenesis induced by the tobacco-specific lung procarcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and that CYP2A5 mediates a noteworthy fraction, but not all, of NNK bioactivation in the lung. The aim of this study was to determine whether other P450s encoded by the Cyp2abfgs gene cluster also play significant roles in NNK lung tumorigenesis. A novel Cyp2abfgs-null mouse was generated, in which all Cyp2a, 2b, 2g, 2f and 2s genes are deleted. The Cyp2abfgs-null mouse was viable, fertile and without discernible physiological abnormalities or compensatory increases in the expression of other P450s. NNK bioactivation in vitro and NNK-induced DNA adduction and lung tumorigenesis in vivo were determined for wild-type (WT) and Cyp2abfgs-null mice; the results were compared with previous findings from Cyp2a5-null mice. The Cyp2abfgs-null mice exhibited significantly lower rates of NNK bioactivation in lung and liver microsomes, compared with either WT or Cyp2a5-null mice. The levels of lung O(6)-methyl guanine DNA adduct were also substantially reduced in Cyp2abfgs-null mice, compared with either WT or Cyp2a5-null mice. Moreover, the Cyp2abfgs-null mice were largely resistant to NNK-induced lung tumorigenesis at both low (50mg/kg) and high (200mg/kg) NNK doses, in contrast to the WT or Cyp2a5-null mice. These results indicate for the first time that, collectively, the CYP2A, 2B, 2F, 2G, and 2S enzymes are indispensable for NNK-induced lung tumorigenesis.

  12. The cytochrome p450 homepage.

    Science.gov (United States)

    Nelson, David R

    2009-10-01

    The Cytochrome P450 Homepage is a universal resource for nomenclature and sequence information on cytochrome P450 ( CYP ) genes. The site has been in continuous operation since February 1995. Currently, naming information for 11,512 CYPs are available on the web pages. The P450 sequences are manually curated by David Nelson, and the nomenclature system conforms to an evolutionary scheme such that members of CYP families and subfamilies share common ancestors. The organisation and content of the Homepage are described.

  13. Mechanistic Scrutiny Identifies a Kinetic Role for Cytochrome b5 Regulation of Human Cytochrome P450c17 (CYP17A1, P450 17A1)

    Science.gov (United States)

    Simonov, Alexandr N.; Holien, Jessica K.; Yeung, Joyee Chun In; Nguyen, Ann D.; Corbin, C. Jo; Zheng, Jie; Kuznetsov, Vladimir L.; Auchus, Richard J.; Conley, Alan J.; Bond, Alan M.; Parker, Michael W.; Rodgers, Raymond J.; Martin, Lisandra L.

    2015-01-01

    Cytochrome P450c17 (P450 17A1, CYP17A1) is a critical enzyme in the synthesis of androgens and is now a target enzyme for the treatment of prostate cancer. Cytochrome P450c17 can exhibit either one or two physiological enzymatic activities differentially regulated by cytochrome b5. How this is achieved remains unknown. Here, comprehensive in silico, in vivo and in vitro analyses were undertaken. Fluorescence Resonance Energy Transfer analysis showed close interactions within living cells between cytochrome P450c17 and cytochrome b5. In silico modeling identified the sites of interaction and confirmed that E48 and E49 residues in cytochrome b5 are essential for activity. Quartz crystal microbalance studies identified specific protein-protein interactions in a lipid membrane. Voltammetric analysis revealed that the wild type cytochrome b5, but not a mutated, E48G/E49G cyt b5, altered the kinetics of electron transfer between the electrode and the P450c17. We conclude that cytochrome b5 can influence the electronic conductivity of cytochrome P450c17 via allosteric, protein-protein interactions. PMID:26587646

  14. Mechanistic Scrutiny Identifies a Kinetic Role for Cytochrome b5 Regulation of Human Cytochrome P450c17 (CYP17A1, P450 17A1.

    Directory of Open Access Journals (Sweden)

    Alexandr N Simonov

    Full Text Available Cytochrome P450c17 (P450 17A1, CYP17A1 is a critical enzyme in the synthesis of androgens and is now a target enzyme for the treatment of prostate cancer. Cytochrome P450c17 can exhibit either one or two physiological enzymatic activities differentially regulated by cytochrome b5. How this is achieved remains unknown. Here, comprehensive in silico, in vivo and in vitro analyses were undertaken. Fluorescence Resonance Energy Transfer analysis showed close interactions within living cells between cytochrome P450c17 and cytochrome b5. In silico modeling identified the sites of interaction and confirmed that E48 and E49 residues in cytochrome b5 are essential for activity. Quartz crystal microbalance studies identified specific protein-protein interactions in a lipid membrane. Voltammetric analysis revealed that the wild type cytochrome b5, but not a mutated, E48G/E49G cyt b5, altered the kinetics of electron transfer between the electrode and the P450c17. We conclude that cytochrome b5 can influence the electronic conductivity of cytochrome P450c17 via allosteric, protein-protein interactions.

  15. N-terminal pro-B-type natriuretic peptide in patients with growth hormone disturbances

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens; Vestergaard, Henrik;

    2007-01-01

    Acromegaly is associated with hypertrophic cardiomyopathy, hypertension and subsequent congestive heart failure. Impairment of cardiac function has also been associated with growth hormone deficiency (GHD). B-type natriuretic peptides (BNPs) have emerged as strong diagnostic and prognostic risk...

  16. Relationship between branching density and crystalline structure of A- and B-type maize mutant starches.

    Science.gov (United States)

    Gérard, C; Planchot, V; Colonna, P; Bertoft, E

    2000-06-02

    Amylopectin from two double maize mutant starches of A-crystalline (wxdu) and B-crystalline type (aewx) was subjected successively to hydrolysis involving alpha and beta amylases, which isolated clusters and all branching zones of clusters (BZC). Enzymatic analysis together with ionic and size-exclusion chromatography revealed the structural features of the clusters and BZC and their role in starch crystallization. A-type clusters were larger (dp(n) > 80) and contained more (but shorter) chains than B-type clusters. The BZC of A-type starch was also larger, but with a shorter distance between the branching points than in B-type BZC. A-type clusters had a densely packed structure and B-type a poorly branched structure. Models for the structure of A- and B-type clusters are presented, and a hypothesis for the influence of cluster geometry on crystallization is proposed.

  17. Mouse B-Type Lamins Are Required for Proper Organogenesis But Not by Embryonic Stem Cells

    OpenAIRE

    Kim, Youngjo; Sharov, Alexei A; McDole, Katie; Cheng, Melody; Hao, Haiping; Fan, Chen-Ming; Gaiano, Nicholas; Minoru S.H. Ko; Zheng, Yixian

    2011-01-01

    B-type lamins, the major components of the nuclear lamina, are believed to be essential for cell proliferation and survival. We found that mouse embryonic stem cells (ESCs) do not need any lamins for self-renewal and pluripotency. Although genome-wide lamin-B binding profiles correlate with reduced gene expression, such binding is not directly required for gene silencing in ESCs or trophectoderm cells. However, B-type lamins are required for proper organogenesis. Defects in spindle orientatio...

  18. The Preparation of B-type Starch Spherocrystals by Freezing Crystallization

    Institute of Scientific and Technical Information of China (English)

    Yan Qi LIU; Jiu Gao YU; Xiu Ping SUN

    2004-01-01

    The B-typed starch spherocrystals were prepared by the dissolution and freezing crystallization of acid-hydrolyzed starch obtained by the mild hydrolysis of maize starch. The spherocrystals were characterized with scanning electron microscope (SEM), X-ray diffraction, thermogravimetry (TG) and gel pervasion chromatogram (GPC). The results show that the preparation was a B-type spherocrystal with the average degree of polymerization of 14 glucose units, and the average diameter of crystal particles was about 7μm.

  19. Discriminating between cardiac and pulmonary dysfunction in the general population with dyspnea by plasma pro-B-type natriuretic peptide

    DEFF Research Database (Denmark)

    Mogelvang, R; Goetze, JP; Schnohr, P;

    2007-01-01

    OBJECTIVES: This study was designed to determine whether measurement of plasma pro-B-type natriuretic peptide (proBNP) could be used in discriminating between cardiac and pulmonary dyspnea in the general population. BACKGROUND: Natriuretic peptides are useful markers in ruling out acute cardiac...... the expected concentration of plasma proBNP based on age and gender was established for dyspneic subjects: an actual plasma proBNP concentration below half of the expected value ruled out left ventricular systolic and diastolic dysfunction (sensitivity 100%, 95% CI 100% to 100%; specificity 15%, 95% CI 12...

  20. Identification of a hemerythrin-like domain in a P1B-type transport ATPase†

    Science.gov (United States)

    Traverso, Matthew E.; Subramanian, Poorna; Davydov, Roman; Hoffman, Brian M.; Stemmler, Timothy L.; Rosenzweig, Amy C.

    2010-01-01

    The P1B-type ATPases couple the energy of ATP hydrolysis to metal ion translocation across cell membranes. Important for prokaryotic metal resistance and essential metal distribution in eukaryotes, P1B-ATPases are divided into subclasses on the basis of their metal substrate specificities. Sequence analysis of putative P1B-5-ATPases, for which the substrate has not been identified, led to the discovery of a C-terminal soluble domain homologous to hemerythrin (Hr) proteins and domains. The Hr domain from the Acidothermus cellulolyticus P1B-5-ATPase was cloned, expressed, and purified (P1B-5-Hr). P1B-5-Hr binds two iron ions per monomer and adopts a predominantly helical fold. Optical absorption features of the iron-loaded and azide-treated protein are consistent with features observed for other Hr proteins. Autooxidation to the met form is very rapid, as reported for other prokaryotic Hr domains. The presence of a diiron center was confirmed by electron paramagnetic resonance (EPR) and X-ray absorption spectroscopic (XAS) data. The occurrence of a Hr-like domain in a P-type ATPase is unprecedented and suggests new regulatory mechanisms as well as an expanded function for Hr proteins in biology. PMID:20672819

  1. B-type natriuretic peptide to predict ductus intervention in infants <28 weeks.

    Science.gov (United States)

    Czernik, Christoph; Lemmer, Julia; Metze, Boris; Koehne, Petra S; Mueller, Christian; Obladen, Michael

    2008-09-01

    Patent ductus arteriosus (PDA) is frequent in neonates with gestational age of less than 28 wk. Clinical and echocardiographic signs define hemodynamic significance of PDA, but do not reveal the need for PDA intervention in the first days of life. B-type natriuretic peptide (BNP) has been proposed as a screening tool for PDA in preterm infants. To determine whether BNP can predict the need for PDA intervention, plasma BNP was measured by chemiluminescence immunoassay in 67 preterm infants <28 wk (median 26) on the second day of life in a prospective blinded study. PDA intervention was based on specified clinical and echocardiographic findings. Twenty-four patients (intervention group) received treatment for PDA and 43 patients (controls) remained without intervention. BNP concentrations were higher in the intervention (median 1069 pg/mL) than in the control group (247 pg/mL, p < 0.001). BNP correlated positively with ductal size (R = 0.46, p < 0.001) and atrial/aortic root ratio (R = 0.54, p < 0.001). In conclusion, plasma BNP proved to be a good predictor for ductus intervention (area under the curve: 0.86) with the best cutoff at 550 pg/mL on the second day of life in ventilated infants less than 28 wk gestation (sensitivity: 83%; specificity: 86%).

  2. Direct regulation of cytochrome c oxidase by calcium ions.

    Directory of Open Access Journals (Sweden)

    Tatiana Vygodina

    Full Text Available Cytochrome c oxidase from bovine heart binds Ca(2+ reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+ shifts the absorption spectrum of heme a, which allowed previously to determine the kinetics and equilibrium characteristics of the binding. However, no effect of Ca(2+ on the functional characteristics of cytochrome oxidase was revealed earlier. Here we report that Ca(2+ inhibits cytochrome oxidase activity of isolated bovine heart enzyme by 50-60% with Ki of ∼1 µM, close to Kd of calcium binding with the oxidase determined spectrophotometrically. The inhibition is observed only at low, but physiologically relevant, turnover rates of the enzyme (∼10 s(-1 or less. No inhibitory effect of Ca(2+ is observed under conventional conditions of cytochrome c oxidase activity assays (turnover number >100 s(-1 at pH 8, which may explain why the effect was not noticed earlier. The inhibition is specific for Ca(2+ and is reversed by EGTA. Na(+ ions that compete with Ca(2+ for binding with the Cation Binding Site, do not affect significantly activity of the enzyme but counteract the inhibitory effect of Ca(2+. The Ca(2+-induced inhibition of cytochrome c oxidase is observed also with the uncoupled mitochondria from several rat tissues. At the same time, calcium ions do not inhibit activity of the homologous bacterial cytochrome oxidases. Possible mechanisms of the inhibition are discussed as well as potential physiological role of Ca(2+ binding with cytochrome oxidase. Ca(2+- binding at the Cation Binding Site is proposed to inhibit proton-transfer through the exit part of the proton conducting pathway H in the mammalian oxidases.

  3. Facile synthesis of B-type carbonated nanoapatite with tailored microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Gualtieri, Magdalena Lassinantti, E-mail: magdalena.gualtieri@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Romagnoli, Marcello, E-mail: marcello.romagnoli@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Hanuskova, Miriam, E-mail: Miriam.hanuskova@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Fabbri, Elena, E-mail: Elena.fabbri@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Gualtieri, Alessandro F., E-mail: Alessandro.gualtieri@unimore.it [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, I-41121 Modena (Italy)

    2014-12-15

    Nanolime and a phosphate-based chelating agent were used to synthesize B-type carbonated apatite. Developed Rietveld refinement strategies allowed one to determine process yield, product crystallinity as well as structural (unit cell) and microstructural (size, strain) parameters. The effect of synthesis temperature (20–60 °C) as well as Ca/P ratio (1.5–2.5) and solid content (10–30 wt%) of the starting batch on these properties were investigated. FTIR, TEM and gas adsorption data provided supporting evidence. The process yield was 42–60 wt% and found to be governed by the Ca/P ratio. The purified products had high specific surface area (107–186 m{sup 2}/g) and crystallinity (76–97%). The unit cell parameters, correlated to the degree of structural carbonate, were sensitive to the Ca/P ratio. Instead, temperature governed the microstructural parameters. Less strained and larger crystals were obtained at higher temperatures. Long-term aging up to 6 months at 20 °C compensated for higher crystal growth kinetics at higher temperature. - Graphical abstract: Controlled synthesis of carbonated apatite at moderate temperatures using nanolime and sodiumhexametaphosphate as starting reagent. - Highlights: • Chemical synthesis of nano-sized apatite with tailored microstructure was performed. • Colloidal Ca(OH){sub 2} and a phosphorus-based chelating agents were used as reagents. • The method is simple and reproducible which facilitate industrial process scale-up. • Rietveld refinement strategies for product characterization were developed. • Rietveld analyses provided yield, microstructural and structure information.

  4. Impact of hemoglobin on plasma pro-B-type natriuretic peptide concentrations in the general population

    DEFF Research Database (Denmark)

    Nybo, Mads; Benn, Marianne; Mogelvang, Rasmus;

    2007-01-01

    BACKGROUND: Age, sex, and renal function contribute to variations in plasma concentrations of B-type natriuretic peptide (BNP) and its molecular precursor (proBNP). Recent studies indicate that anemia may also affect proBNP concentrations in patients with heart failure or stroke. However, the imp......BACKGROUND: Age, sex, and renal function contribute to variations in plasma concentrations of B-type natriuretic peptide (BNP) and its molecular precursor (proBNP). Recent studies indicate that anemia may also affect proBNP concentrations in patients with heart failure or stroke. However...

  5. Salsolinol, a catechol neurotoxin, induces oxidative modification of cytochrome c

    Directory of Open Access Journals (Sweden)

    Jung Hoon Kang

    2013-02-01

    Full Text Available Methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (salsolinol,an endogenous neurotoxin, is known to perform a role in thepathogenesis of Parkinson’s disease (PD. In this study, weevaluated oxidative modification of cytochrome c occurring afterincubation with salsolinol. When cytochrome c was incubatedwith salsolinol, protein aggregation increased in a dosedependentmanner. The formation of carbonyl compounds andthe release of iron were obtained in salsolinol- treated cytochromec. Salsolinol also led to the release of iron fromcytochrome c. Reactive oxygen species (ROS scavengers andiron specific chelator inhibited the salsolinol-mediated cytochromec modification and carbonyl compound formation. It issuggested that oxidative damage of cytochrome c by salsolinolmight induce the increase of iron content in cells, subsequentlyleading to the deleterious condition which was observed. Thismechanism may, in part, provide an explanation for thedeterioration of organs under neurodegenerative disorders suchas PD. [BMB Reports 2013; 46(2: 119-123

  6. Discovery of a magnetic field in the early B-type star σ Lupi

    NARCIS (Netherlands)

    Henrichs, H.F.; Kolenberg, K.; Plaggenborg, B.; Marsden, S.C.; Waite, I.A.; Landstreet, J.D.; Wade, G.A.; Grunhut, J.H.; Oksala, M.E.

    2012-01-01

    Context. Magnetic early B-type stars are rare. Indirect indicators are needed to identify them before investing in time-intensive spectropolarimetric observations. Aims. We use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of ultraviolet (UV) stellar

  7. Characterization of A- and B-type starch granules in Chinese wheat cultivars

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan; GUO Qi; FENG Nan; WANG Jin-rong; WANG Shu-jun; HE Zhong-hu

    2016-01-01

    Starch is the major component of wheat lfour and serves as a multifunctional ingredient in food industry. The objective of the present study was to investigate starch granule size distribution of Chinese wheat cultivars, and to compare structure and functionality of starches in four leading cultivars Zhongmai 175, CA12092, Lunxuan 987, and Zhongyou 206. A wide variation in volume percentages of A- and B-type starch granules among genotypes was observed. Volume percentages of A- and B-type granules had ranges of 68.4–88.9% and 9.7–27.9% in the ifrst cropping seasons, 74.1–90.1% and 7.2–25.3% in the second. Wheat cultivars with higher volume percentages of A- and B-type granules could serve as parents in breeding program for selecting high and low amylose wheat cultivars, respectively. In comparison with the B-type starch granules, the A-type granules starch showed difference in three aspects: (1) higher amount of ordered short-range structure and a lower relative crystalinity, (2) higher gelatinization onset (To) temperatures and enthalpies (ΔH), and lower gelatinization conclusion temperatures (Tc), (3) greater peak, though, and ifnal viscosity, and lower breakdown viscosity and pasting temperature. It provides important information for breeders to develop potentialy useful cultivars with particular functional properties of their starches suited to speciifc applications.

  8. Spectroscopic Evidence for an Oxazolone Structure in Anionic b-Type Peptide Fragments

    NARCIS (Netherlands)

    Grzetic, J.; Oomens, J.

    2012-01-01

    Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b(2) fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm(-1) spectral range by multiple-photon dissociation (MP

  9. Spectroscopic evidence for an oxazolone structure in anionic b-type peptide fragments

    NARCIS (Netherlands)

    J. Grzetic; J. Oomens

    2012-01-01

    Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b2 fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm-1 spectral range by multiple-photon dissociation (MPD) s

  10. Data Mining Rules for Ultrasonic B-Type Detection and Diagnosis for Cholecystolithiasis

    Institute of Scientific and Technical Information of China (English)

    LOU Wei; YAN Li-min; HE Guo-sen

    2004-01-01

    This paper presents realistic data mining based on the data of B-type ultrasonic detection and diagnosis for cholrcystolithiasis (gallbladder stone in biliary tract) recorded by a district central hospital in Shanghai during the past several years. Computer simulation and modeling is described.

  11. Cytochrome P3-450 cDNA encodes aflatoxin B1-4-hydroxylase.

    Science.gov (United States)

    Faletto, M B; Koser, P L; Battula, N; Townsend, G K; Maccubbin, A E; Gelboin, H V; Gurtoo, H L

    1988-09-01

    Aflatoxin B1 (AFB1), a potent hepatocarcinogen and ubiquitous dietary contaminant in some countries, is detoxified to aflatoxin M1 (AFM1) via cytochrome P-450-mediated AFB1-4-hydroxylase. Genetic studies in mice have demonstrated that the expression of AFB1-4-hydroxylase is regulated by the aryl hydrocarbon locus and suggested that different cytochrome P-450 isozymes catalyze AFB1-4-hydroxylase and aryl hydrocarbon hydroxylase activities. We have now examined lysates from mammalian cells infected with recombinant vaccinia viruses containing expressible cytochrome P1-450 or P3-450 cDNAs for their ability to metabolize AFB1 to AFM1. Our results show that cytochrome P3-450 cDNA specifies AFB1-4-hydroxylase. This is the first direct assignment of a specific cytochrome P-450 to an AFB1 detoxification pathway. This finding may have relevance to the dietary modulation of AFB1 hepatocarcinogenesis.

  12. Acrolein, A Reactive Product of Lipid Peroxidation, Induces Oxidative Modification of Cytochrome c

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jung Hoon [Cheongju Univ., Cheongju (Korea, Republic of)

    2013-11-15

    Acrolein (ACR) is a well-known carbonyl toxin produced by lipid peroxidation of polyunsaturated fatty acids, which is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). In Alzheimer's brain, ACR was found to be elevated in hippocampus and temporal cortex where oxidative stress is high. In this study, we evaluated oxidative modification of cytochrome c occurring after incubation with ACR. When cytochrome c was incubated with ACR, protein aggregation increased in a dose-dependent manner. The formation of carbonyl compounds and the release of iron were obtained in ACR-treated cytochrome c. Reactive oxygen species scavengers and iron specific chelator inhibited the ACR-mediated cytochrome c modification and carbonyl compound formation. Our data demonstrate that oxidative damage of cytochrome c by ACR might induce disruption of cyotochrome c structure and iron mishandling as a contributing factor to the pathology of AD.

  13. Rcf1 mediates cytochrome oxidase assembly and respirasome formation, revealing heterogeneity of the enzyme complex.

    Science.gov (United States)

    Vukotic, Milena; Oeljeklaus, Silke; Wiese, Sebastian; Vögtle, F Nora; Meisinger, Chris; Meyer, Helmut E; Zieseniss, Anke; Katschinski, Doerthe M; Jans, Daniel C; Jakobs, Stefan; Warscheid, Bettina; Rehling, Peter; Deckers, Markus

    2012-03-01

    The terminal enzyme of the mitochondrial respiratory chain, cytochrome oxidase, transfers electrons to molecular oxygen, generating water. Within the inner mitochondrial membrane, cytochrome oxidase assembles into supercomplexes, together with other respiratory chain complexes, forming so-called respirasomes. Little is known about how these higher oligomeric structures are attained. Here we report on Rcf1 and Rcf2 as cytochrome oxidase subunits in S. cerevisiae. While Rcf2 is specific to yeast, Rcf1 is a conserved subunit with two human orthologs, RCF1a and RCF1b. Rcf1 is required for growth in hypoxia and complex assembly of subunits Cox13 and Rcf2, as well as for the oligomerization of a subclass of cytochrome oxidase complexes into respirasomes. Our analyses reveal that the cytochrome oxidase of mitochondria displays intrinsic heterogeneity with regard to its subunit composition and that distinct forms of respirasomes can be formed by complex variants.

  14. Construction of a 3D model of cytochrome P450 2B4.

    Science.gov (United States)

    Chang, Y T; Stiffelman, O B; Vakser, I A; Loew, G H; Bridges, A; Waskell, L

    1997-02-01

    A three-dimensional structural model of rabbit phenobarbital-inducible cytochrome P450 2B4 (LM2) was constructed by homology modeling techniques previously developed for building and evaluating a 3D model of the cytochrome P450choP isozyme. Four templates with known crystal structures including cytochrome P450cam, terp, BM-3 and eryF were used in multiple sequence alignments and construction of the cytochrome P450 2B4 coordinates. The model was evaluated for its overall quality using available protein analysis programs and found to be satisfactory. The model structure was stable at room temperature during a 140 ps unconstrained full protein molecular dynamics simulation. A putative substrate access channel and binding site were identified. Two different substrates, benzphetamine and androstenedione, that are metabolized by cytochrome P450 2B4 with pronounced product specificity were docked into the putative binding site. Two orientations were found for each substrate that could lead to the observed preferred products. Using a geometric fit method three regions on the surface of the model cytochrome P450 structure were identified as possible sites for interaction with cytochrome b5, a redox partner of P450 2B4. Residues that may interact with the substrates and with cytochrome b5 have been identified and mutagenesis studies are currently in progress.

  15. Cation binding site of cytochrome c oxidase: progress report.

    Science.gov (United States)

    Vygodina, Tatiana V; Kirichenko, Anna; Konstantinov, Alexander A

    2014-07-01

    Cytochrome c oxidase from bovine heart binds Ca(2+) reversibly at a specific Cation Binding Site located near the outer face of the mitochondrial membrane. Ca(2+) shifts the absorption spectrum of heme a, which allowed earlier the determination of the kinetic and equilibrium characteristics of the binding, and, as shown recently, the binding of calcium to the site inhibits cytochrome oxidase activity at low turnover rates of the enzyme [Vygodina, Т., Kirichenko, A., Konstantinov, A.A (2013). Direct Regulation of Cytochrome c Oxidase by Calcium Ions. PloS ONE 8, e74436]. This paper summarizes further progress in the studies of the Cation Binding Site in this group presenting the results to be reported at 18th EBEC Meeting in Lisbon, 2014. The paper revises specificity of the bovine oxidase Cation Binding Site for different cations, describes dependence of the Ca(2+)-induced inhibition on turnover rate of the enzyme and reports very high affinity binding of calcium with the "slow" form of cytochrome oxidase. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Guest Editors: Manuela Pereira and Miguel Teixeira.

  16. Cytochrome c and insect cell apoptosis

    Institute of Scientific and Technical Information of China (English)

    Kai-Yu Liu; Hong Yang; Jian-Xin Peng; Hua-Zhu Hong

    2012-01-01

    The role ofcytochrome c in insect cell apoptosis has drawn considerable attention and has been subject to considerable controversy.In Drosophila,the majority of studies have demonstrated that cytochrome c may not be involved in apoptosis,although there are conflicting reports.Cytochrome c is not released from mitochondria into the cytosol and activation of the initiator caspase Dronc or effector caspase Drice is not associated with cytochrome c during apoptosis in Drosophila SL2 cells or BG2 cells.Cytochrome c failed to induce caspase activation and promote caspase activation in Drosophila cell lysates,but remarkably caused caspase activation in extracts from human cells.Knockdown of cytochrome c does not protect cells from apoptosis and over-expression of cytochrome c also does not promote apoptosis.Structural analysis has revealed that cytochrome c is not required for Dapaf-1 complex assembly.In Lepidoptera,the involvement of cytochrome c in apoptosis has been demonstrated by the accumulating evidence.Cytochrome c release from mitochondria into cytosol has been observed in different cell lines such as Spodoptera frugiperda Sf9,Spodoptera litura S1-1 and Lymantria dispar LdFB.Silencing of cytochrome c expression significantly affected apoptosis and activation of caspase and the addition of cytochrome c to cell-free extracts results in caspase activation,suggesting the activation of caspase is dependent on cytochrome c.Although Apaf- 1 has not been identified in Lepidoptera,the inhibitor of apoptosome formation can inhibit apoptosis and caspase activation.Cytochrome c may be exclusively required for Lepidoptera apoptosis.

  17. New genes encoding subunits of a cytochrome bc1-analogous complex in the respiratory chain of the hyperthermoacidophilic crenarchaeon Sulfolobus acidocaldarius.

    Science.gov (United States)

    Hiller, A; Henninger, T; Schäfer, G; Schmidt, C L

    2003-04-01

    The soxL gene from Sulfolobus acidocaldarius (DSM 639) encodes a Rieske iron-sulfur protein. In this study we report the identification of two open reading frames in its downstream region. The first one, named soxN, codes for a membrane protein bearing a resemblance to the b-type cytochromes of the cytochrome bc1 and b6f complexes. The protein is predicted to contain at least 10 transmembrane helices and features the two conserved histidine pairs coordinating the heme groups of these cytochromes. The second open reading frame, named odsN, encodes a soluble protein of unknown function. The genomic region displays a complex transcription pattern. Northern blot and RT-PCR analyses revealed the presence of mono- and bi-cistronic transcripts as well as a tri-cistronic transcript of soxL and cbsAB, encoding the mono-heme cytochrome b558/566. Phylogenetic analyses of the genes of the soxLN pair and of other archaeal gene pairs encoding Rieske iron-sulfur proteins and b-type cytochromes revealed an identical branching patterns for both protein families, suggesting an evolutionary link of these genes provided by the functional interaction of the proteins. On the basis of the findings of this study and the previously studied properties of the soxL and cbsA proteins, we propose the occurrence of a novel cytochrome bc1-analogous complex in the membranes of Sulfolobus, consisting of the cytochrome b homolog soxN, the Rieske protein soxL, the high potential cytochrome cbsA, as well as the non-redox-active subunits cbsB and odsN.

  18. Evaluation of cytochrome P-450 concentration in Saccharomyces cerevisiae strains

    Directory of Open Access Journals (Sweden)

    Míriam Cristina Sakuragui Matuo

    2010-09-01

    Full Text Available Saccharomyces cerevisiae has been widely used in mutagenicity tests due to the presence of a cytochrome P-450 system, capable of metabolizing promutagens to active mutagens. There are a large number of S. cerevisiae strains with varying abilities to produce cytochrome P-450. However, strain selection and ideal cultivation conditions are not well defined. We compared cytochrome P-450 levels in four different S. cerevisiae strains and evaluated the cultivation conditions necessary to obtain the highest levels. The amount of cytochrome P-450 produced by each strain varied, as did the incubation time needed to reach the maximum level. The highest cytochrome P-450 concentrations were found in media containing fermentable sugars. The NCYC 240 strain produced the highest level of cytochrome P-450 when grown in the presence of 20 % (w/v glucose. The addition of ethanol to the media also increased cytochrome P-450 synthesis in this strain. These results indicate cultivation conditions must be specific and well-established for the strain selected in order to assure high cytochrome P-450 levels and reliable mutagenicity results.Linhagens de Saccharomyces cerevisiae tem sido amplamente empregadas em testes de mutagenicidade devido à presença de um sistema citocromo P-450 capaz de metabolizar substâncias pró-mutagênicas à sua forma ativa. Devido à grande variedade de linhagens de S. cerevisiae com diferentes capacidades de produção de citocromo P-450, torna-se necessária a seleção de cepas, bem como a definição das condições ideais de cultivo. Neste trabalho, foram comparados os níveis de citocromo P-450 em quatro diferentes linhagens de S. cerevisiae e avaliadas as condições de cultivo necessárias para obtenção de altas concentrações deste sistema enzimático. O maior nível enzimático foi encontrado na linhagem NCYC 240 em presença de 20 % de glicose (p/v. A adição de etanol ao meio de cultura também produziu um aumento na s

  19. Mouse B-Type Lamins Are Required for Proper Organogenesis But Not by Embryonic Stem Cells

    Science.gov (United States)

    Kim, Youngjo; Sharov, Alexei A.; McDole, Katie; Cheng, Melody; Hao, Haiping; Fan, Chen-Ming; Gaiano, Nicholas; Ko, Minoru S. H.; Zheng, Yixian

    2012-01-01

    B-type lamins, the major components of the nuclear lamina, are believed to be essential for cell proliferation and survival. We found that mouse embryonic stem cells (ESCs) do not need any lamins for self-renewal and pluripotency. Although genome-wide lamin-B binding profiles correlate with reduced gene expression, such binding is not directly required for gene silencing in ESCs or trophectoderm cells. However, B-type lamins are required for proper organogenesis. Defects in spindle orientation in neural progenitor cells and migration of neurons probably cause brain disorganizations found in lamin-B null mice. Thus, our studies not only disprove several prevailing views of lamin-Bs but also establish a foundation for redefining the function of the nuclear lamina in the context of tissue building and homeostasis. PMID:22116031

  20. PROJECTED ROTATIONAL VELOCITIES OF 136 EARLY B-TYPE STARS IN THE OUTER GALACTIC DISK

    Energy Technology Data Exchange (ETDEWEB)

    Garmany, C. D.; Glaspey, J. W. [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719 (United States); Bragança, G. A.; Daflon, S.; Fernandes, M. Borges; Cunha, K. [Observatório Nacional-MCTI, Rua José Cristino, 77. CEP: 20921-400, Rio de Janeiro, RJ (Brazil); Oey, M. S. [University of Michigan, Department of Astronomy, 311 West Hall, 1085 S. University Ave., Ann Arbor, MI: 48109-1107 (United States); Bensby, T., E-mail: garmany@noao.edu [Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-22100, Lund (Sweden)

    2015-08-15

    We have determined projected rotational velocities, v sin i, from Magellan/MIKE echelle spectra for a sample of 136 early B-type stars having large Galactocentric distances. The target selection was done independently of their possible membership in clusters, associations or field stars. We subsequently examined the literature and assigned each star as Field, Association, or Cluster. Our v sin i results are consistent with a difference in aggregate v sin i with stellar density. We fit bimodal Maxwellian distributions to the Field, Association, and Cluster subsamples representing sharp-lined and broad-lined components. The first two distributions, in particular, for the Field and Association are consistent with strong bimodality in v sin i. Radial velocities are also presented, which are useful for further studies of binarity in B-type stars, and we also identify a sample of possible new double-lined spectroscopic binaries. In addition, we find 18 candidate Be stars showing emission at Hα.

  1. N-terminal-pro-B-type natriuretic peptide during pharmacological heart rate reduction in hyperthyroidism

    DEFF Research Database (Denmark)

    Schultz, M; Kistorp, C; Corell, P

    2009-01-01

    We hypothesized that elevated N-terminal-pro-B-type natriuretic peptide levels in hyperthyroidism are mainly driven by increased metabolism due to excess thyroid hormones. Therefore, serum levels of N-terminal-pro-B-type natriuretic peptide were studied during reduced cardiac work load by means...... of pharmacologically induced heart rate reduction in untreated hyperthyroidism. We designed a noncontrolled interventional study. Eighteen women with newly diagnosed hyperthyroidism were evaluated (including an echocardiography) before and after pharmacological heart rate reduction with 360 mg verapamil daily for 6......-index decreased from median 319 to 315 arbitrary units (p=0.039) and free triiodothyronine-index increased from 8.6 to 9.9 arbitrary units (p=0.010). No changes in echocardiographic parameters were observed. A decrease in resting heart rate in untreated hyperthyroidism due to verapamil treatment did not result...

  2. Spectroscopic Evidence for an Oxazolone Structure in Anionic b-Type Peptide Fragments

    Science.gov (United States)

    Grzetic, Josipa; Oomens, Jos

    2012-02-01

    Infrared spectra of anionic b-type fragments generated by collision induced dissociation (CID) from deprotonated peptides are reported. Spectra of the b2 fragments of deprotonated AlaAlaAla and AlaTyrAla have been recorded over the 800-1800 cm-1 spectral range by multiple-photon dissociation (MPD) spectroscopy using an FTICR mass spectrometer in combination with the free electron laser FELIX. Structural characterization of the b-type fragments is accomplished by comparison with density functional theory calculated spectra at the B3LYP/6-31++G(d,p) level for different isomeric structures. Although diketopiperazine structures represent the energetically lowest isomers, the IR spectra suggest an oxazolone structure for the b2 fragments of both peptides. Deprotonation is shown to occur on the oxazolone α-carbon, which leads to a conjugated structure in which the negative charge is practically delocalized over the entire oxazolone ring, providing enhanced gas-phase stability.

  3. Photometric amplitudes and phases of B-type main sequence pulsators: sources of inaccuracy

    CERN Document Server

    Szewczuk, Wojciech

    2010-01-01

    We discuss all possible sources of uncertainties in theoretical values of the photometric amplitudes and phases of B-type main sequence pulsators. These observables are of particular importance because they contain information about the mode geometry as well as about stellar physics. Here, we study effects of various parameters coming both from theory of linear nonadiabatic oscillations and from models of stellar atmospheres. In particular, we show effects of chemical composition, opacities and, for the first time, effects of the NLTE atmospheres.

  4. Cardiac resynchronization therapy and B-type natriuretic peptide in heart failure

    Institute of Scientific and Technical Information of China (English)

    HUANG De-jia

    2009-01-01

    @@ Cardiac resynchronization therapy (CRT) improves left ventricular function, symptom status, quality of life and reduces hospitalization and mortality in patients with New York Heart Association (NYHA) Class Ⅲ or IV heart failure and intraventricular conduction delay despite optimal medical management.1 B-type natriuretic peptide (BNP) and its amino terminal cleavage equivalent (NT-pro BNP) levels correlate with the severity of heart failure and predict prognosis of heart failure patients.2

  5. B-Type Natriuretic Peptide Modulates Ghrelin, Hunger, and Satiety in Healthy Men

    OpenAIRE

    Vila, Greisa; Grimm, Gabriele; Resl, Michael; Heinisch, Birgit; Einwallner, Elisa; Esterbauer, Harald; Dieplinger, Benjamin; Mueller, Thomas; Luger, Anton; Clodi, Martin

    2012-01-01

    Chronic heart failure is accompanied by anorexia and increased release of B-type natriuretic peptide (BNP) from ventricular cardiomyocytes. The pathophysiological mechanisms linking heart failure and appetite regulation remain unknown. In this study, we investigated the impact of intravenous BNP administration on appetite-regulating hormones and subjective ratings of hunger and satiety in 10 healthy volunteers. Participants received in a randomized, placebo-controlled, crossover, single-blind...

  6. [The role of B type natriuretic peptide in the assessment of post myocardial infarction prognosis].

    Science.gov (United States)

    Ben Halima, A; Ibn el Hadj, Z; Chrigui, R; Kammoun, I; Lefi, A; Chine, S; Gargouri, S; Keskes, H; Kachboura, S

    2006-10-01

    Recently cardiac peptides have received close attention as cardiovascular markers. Brain (B type) natriuretic peptide is a neurohormone synthesized predominantly in ventricular myocardium. Previous studies have shown that this hormone can provide prognostic information in patients with myocardial infarction. The aim of this review is to evaluate the impact of plasma levels of BNP on prediction of left ventricular ejection fraction and remodelling and major cardiac events after myocardial infarction.

  7. The VLT-FLAMES Tarantula Survey XXII. Multiplicity properties of the B-type stars

    CERN Document Server

    Dunstall, P R; Sana, H; Evans, C J; Howarth, I D; Simón-Díaz, S; de Mink, S E; Langer, N; Apellániz, J Maíz; Taylor, W D

    2015-01-01

    We investigate the multiplicity properties of 408 B-type stars observed in the 30 Doradus region of the Large Magellanic Cloud with multi-epoch spectroscopy from the VLT-FLAMES Tarantula Survey (VFTS). We use a cross-correlation method to estimate relative radial velocities from the helium and metal absorption lines for each of our targets. Objects with significant radial-velocity variations (and with an amplitude larger than 16 km/s) are classified as spectroscopic binaries. We find an observed spectroscopic binary fraction (defined by periods of 0.1) for the B-type stars, f_B(obs) = 0.25 +/- 0.02, which appears constant across the field of view, except for the two older clusters (Hodge 301 and SL 639). These two clusters have significantly lower fractions of 0.08 +/- 0.08 and 0.10 +/- 0.09, respectively. Using synthetic populations and a model of our observed epochs and their potential biases, we constrain the intrinsic multiplicity properties of the dwarf and giant (i.e. relatively unevolved) B-type stars ...

  8. An Einstein Observatory SAO-based catalog of B-type stars

    Science.gov (United States)

    Grillo, F.; Sciortino, S.; Micela, G.; Vaiana, G. S.; Harnden, F. R., Jr.

    1992-01-01

    About 4000 X-ray images obtained with the Einstein Observatory are used to measure the 0.16-4.0 keV emission from 1545 B-type SAO stars falling in the about 10 percent of the sky surveyed with the IPC. Seventy-four detected X-ray sources with B-type stars are identified, and it is estimated that no more than 15 can be misidentified. Upper limits to the X-ray emission of the remaining stars are presented. In addition to summarizing the X-ray measurements and giving other relevant optical data, the present extensive catalog discusses the reduction process and analyzes selection effects associated with both SAO catalog completeness and IPC target selection procedures. It is concluded that X-ray emission, at the level of Lx not less than 10 exp 30 ergs/s, is quite common in B stars of early spectral types (B0-B3), regardless of luminosity class, but that emission, at the same level, becomes less common, or nonexistent, in later B-type stars.

  9. B-type esterases in the snail Xeropicta derbentina: An enzymological analysis to evaluate their use as biomarkers of pesticide exposure

    Energy Technology Data Exchange (ETDEWEB)

    Laguerre, Christel [Universite d' Avignon et des Pays de Vaucluse, UMR 406 UAPV/INRA, F-84914 Avignon (France); INRA, Laboratoire de Toxicologie Environnementale, UMR 406 UAPV/INRA, F-84914 Avignon (France); Sanchez-Hernandez, Juan C. [Laboratory of Ecotoxicology, Faculty of Environmental Science, University of Castilla-La Mancha, Avda. Carlos III s/n, 45071 Toledo (Spain); Koehler, Heinz R. [Animal Physiological Ecology, University of Tuebingen, Konrad-Adenauer-Strasse 20, D-72072 Tuebingen (Germany); Triebskorn, Rita [Animal Physiological Ecology, University of Tuebingen, Konrad-Adenauer-Strasse 20, D-72072 Tuebingen (Germany); Steinbeis-Transfer Center for Ecotoxicology and Ecophysiology, Blumenstrasse 13, D-72108 Rottenburg (Germany); Capowiez, Yvan [INRA, Unite PSH, F- 84914 Avignon (France); Rault, Magali [Universite d' Avignon et des Pays de Vaucluse, UMR 406 UAPV/INRA, F-84914 Avignon (France); INRA, Laboratoire de Toxicologie Environnementale, UMR 406 UAPV/INRA, F-84914 Avignon (France); Mazzia, Christophe [Universite d' Avignon et des Pays de Vaucluse, UMR 406 UAPV/INRA, F-84914 Avignon (France); INRA, Laboratoire de Toxicologie Environnementale, UMR 406 UAPV/INRA, F-84914 Avignon (France)], E-mail: mazzia@avignon.inra.fr

    2009-01-15

    The study was prompted to characterize the B-type esterase activities in the terrestrial snail Xeropicta derbentina and to evaluate its sensitivity to organophosphorus and carbamate pesticides. Specific cholinesterase and carboxylesterase activities were mainly obtained with acetylthiocholine (K{sub m} = 77.2 mM; V{sub max} = 38.2 mU/mg protein) and 1-naphthyl acetate (K{sub m} = 222 mM, V{sub max} = 1095 mU/mg protein) substrates, respectively. Acetylcholinesterase activity was concentration-dependently inhibited by chlorpyrifos-oxon, dichlorvos, carbaryl and carbofuran (IC50 = 1.35 x 10{sup -5}-3.80 x 10{sup -8} M). The organophosphate-inhibited acetylcholinesterase activity was reactivated in the presence of pyridine-2-aldoxime methochloride. Carboxylesterase activity was inhibited by organophosphorus insecticides (IC50 = 1.20 x 10{sup -5}-2.98 x 10{sup -8} M) but not by carbamates. B-esterase-specific differences in the inhibition by organophosphates and carbamates are discussed with respect to the buffering capacity of the carboxylesterase to reduce pesticide toxicity. These results suggest that B-type esterases in X. derbentina are suitable biomarkers of pesticide exposure and that this snail could be used as sentinel species in field monitoring of Mediterranean climate regions. - Characterization of the B-type esterases in the terrestrial snail Xeropicta derbentina in order to evaluate pesticide exposure.

  10. Cytochrome c2-independent respiratory growth of Rhodobacter capsulatus.

    OpenAIRE

    Daldal, F

    1988-01-01

    To assess the role of cytochrome c2 as a respiratory electron carrier, we obtained a double mutant of Rhodobacter capsulatus defective in cytochrome c2 and in the quinol oxidase260. This mutant was able to grow chemoheterotrophically, indicating that an electron pathway independent of cytochrome c2 was functional between the ubiquinol:cytochrome c2 oxidoreductase and the cytochrome oxidase410.

  11. Mitochondrial cytochrome c oxidase deficiency.

    Science.gov (United States)

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-03-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.

  12. Secologanin synthase which catalyzes the oxidative cleavage of loganin into secologanin is a cytochrome P450.

    Science.gov (United States)

    Yamamoto, H; Katano, N; Ooi, A; Inoue, K

    2000-01-01

    Secologanin synthase, an enzyme catalyzing the oxidative cleavage of the cyclopentane ring in loganin to form secologanin, was detected in microsomal preparations from cell suspension cultures of Lonicera japonica. The reaction required NADPH and molecular oxygen, and was blocked by carbon monoxide as well as by several other cytochrome P450 inhibitors, indicating that the reaction was mediated by cytochrome P450. Of the substrates examined, only specificity for loganin was demonstrated. A possible reaction mechanism is described.

  13. DAC is involved in the accumulation of the cytochrome b6/f complex in Arabidopsis.

    Science.gov (United States)

    Xiao, Jianwei; Li, Jing; Ouyang, Min; Yun, Tao; He, Baoye; Ji, Daili; Ma, Jinfang; Chi, Wei; Lu, Congming; Zhang, Lixin

    2012-12-01

    The biogenesis and assembly of photosynthetic multisubunit protein complexes is assisted by a series of nucleus-encoded auxiliary protein factors. In this study, we characterize the dac mutant of Arabidopsis (Arabidopsis thaliana), which shows a severe defect in the accumulation of the cytochrome b(6)/f complex, and provide evidence suggesting that the efficiency of cytochrome b(6)/f complex assembly is affected in the mutant. DAC is a thylakoid membrane protein with two predicted transmembrane domains that is conserved from cyanobacteria to vascular plants. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation analyses revealed a specific interaction between DAC and PetD, a subunit of the cytochrome b(6)/f complex. However, DAC was found not to be an intrinsic component of the cytochrome b(6)/f complex. In vivo chloroplast protein labeling experiments showed that the labeling rates of the PetD and cytochrome f proteins were greatly reduced, whereas that of the cytochrome b(6) protein remained normal in the dac mutant. DAC appears to be a novel factor involved in the assembly/stabilization of the cytochrome b(6)/f complex, possibly through interaction with the PetD protein.

  14. Complex asteroseismology of the hybrid B-type pulsator $\\gamma$ Pegasi: a test of stellar opacities

    CERN Document Server

    Walczak, Przemysław

    2010-01-01

    Using the updated oscillation spectrum of $\\gamma$ Pegasi, we construct a set of seismic models which reproduce two pulsational frequencies corresponding to the $\\ell=0$, p$_1$ and $\\ell=1$, g$_1$ modes. Then, we single out models which reproduce other well identified modes. Finally, we extend our seismic modelling by a requirement of fitting also values of the complex, nonadiabatic parameter $f$ associated to each mode frequency. Such complex asteroseismology of the B-type pulsators provides a unique test of stellar metallicity and opacities. In contrast to our previous studies, results for $\\gamma$ Peg indicate that both opacity tables, OPAL and OP, are equally preferred.

  15. VizieR Online Data Catalog: Spectrocopic Binarity of O and B type stars (Chini+, 2012)

    Science.gov (United States)

    Chini, R.; Hoffmeister, V. H.; Nasseri, A.; Stahl, O.; Zinnecker, H.

    2013-05-01

    We have performed a comprehensive spectroscopic survey on a large representative sample of 249 O- and 581 B-type stars. Using the high-resolution spectrograph BESO at the Hexapod Telescope at the Universitatssternwarte Bochum near Cerro Armazones in Chile, we obtained 3632 multi-epoch optical spectra. The observing period started in 2009 January and is still going on. The spectra comprise a wavelength range from 3620 to 8530Å and provide a mean spectral resolution of R=50000. (1 data file).

  16. Emission from the Centrifugal Magnetospheres of Magnetic B-type Stars

    Science.gov (United States)

    Shultz, M.; Wade, G.; Rivinius, T.; Townsend, R.; MiMeS Collaboration

    2016-11-01

    Approximately 10% of B-type stars possess strong magnetic fields, and of these, 25% host centrifugal magnetospheres in which the radiative wind, magnetic field, and rotational support interact to form a dense circumstellar plasma visible in a variety of diagnostic lines. In this article we review the basic theory behind CMs, outline current theoretical and observational problems, compare the observational properties of CM host stars to those of classical Be stars, and finally present preliminary results of a population study aimed at clarifying the characteristics of this growing sub-class.

  17. Emission from the Centrifugal Magnetospheres of Magnetic B-type Stars

    CERN Document Server

    Shultz, Matt; Rivinius, Thomas; Townsend, Richard

    2014-01-01

    Approximately 10% of B-type stars possess strong magnetic fields, and of these, 25% host centrifugal magnetospheres (CMs) in which the radiative wind, magnetic field, and rotational support interact to form a dense circumstellar plasma visible in a variety of diagnostic lines. In this article we review the basic theory behind CMs, outline current theoretical and observational problems, compare the observational properties of CM host stars to those of classical Be stars, and finally present preliminary results of a population study aimed at clarifying the characteristics of this growing sub-class.

  18. A cytochrome cbb3 (cytochrome c) terminal oxidase in Azospirillum brasilense Sp7 supports microaerobic growth.

    Science.gov (United States)

    Marchal, K; Sun, J; Keijers, V; Haaker, H; Vanderleyden, J

    1998-11-01

    Spectral analysis indicated the presence of a cytochrome cbb3 oxidase under microaerobic conditions in Azospirillum brasilense Sp7 cells. The corresponding genes (cytNOQP) were isolated by using PCR. These genes are organized in an operon, preceded by a putative anaerobox. The phenotype of an A. brasilense cytN mutant was analyzed. Under aerobic conditions, the specific growth rate during exponential phase (mu(e)) of the A. brasilense cytN mutant was comparable to the wild-type specific growth rate (m(e) of approximately 0.2 h-1). In microaerobic NH4+-supplemented conditions, the low respiration of the A. brasilense cytN mutant affected its specific growth rate (mu(e) of approximately 0.02 h-1) compared to the wild-type specific growth rate (mu(e) of approximately 0.2 h-1). Under nitrogen-fixing conditions, both the growth rates and respiration of the wild type were significantly diminished in comparison to those under NH4+-supplemented conditions. Differences in growth rates and respiration between the wild type and the A. brasilense cytN mutant were less pronounced under these nitrogen-fixing conditions (mu(e) of approximately 0.03 h-1 for the wild type and 0.02 h-1 for the A. brasilense cytN mutant). The nitrogen-fixing capacity of the A. brasilense cytN mutant was still approximately 80% of that determined for the wild-type strain. This leads to the conclusion that the A. brasilense cytochrome cbb3 oxidase is required under microaerobic conditions, when a high respiration rate is needed, but that under nitrogen-fixing conditions the respiration rate does not seem to be a growth-limiting factor.

  19. Identification of a major QTL controlling the content of B-type starch granules in Aegilops

    Science.gov (United States)

    Howard, Thomas; Rejab, Nur Ardiyana; Griffiths, Simon; Leigh, Fiona; Leverington-Waite, Michelle; Simmonds, James; Uauy, Cristobal; Trafford, Kay

    2011-01-01

    Starch within the endosperm of most species of the Triticeae has a unique bimodal granule morphology comprising large lenticular A-type granules and smaller near-spherical B-type granules. However, a few wild wheat species (Aegilops) are known to lack B-granules. Ae. peregrina and a synthetic tetraploid Aegilops with the same genome composition (SU) were found to differ in B-granule number. The synthetic tetraploid had normal A- and B-type starch granules whilst Ae. peregrina had only A-granules because the B-granules failed to initiate. A population segregating for B-granule number was generated by crossing these two accessions and was used to study the genetic basis of B-granule initiation. A combination of Bulked Segregant Analysis and QTL mapping identified a major QTL located on the short arm of chromosome 4S that accounted for 44.4% of the phenotypic variation. The lack of B-granules in polyploid Aegilops with diverse genomes suggests that the B-granule locus has been lost several times independently during the evolution of the Triticeae. It is proposed that the B-granule locus is susceptible to silencing during polyploidization and a model is presented to explain the observed data based on the assumption that the initiation of B-granules is controlled by a single major locus per haploid genome. PMID:21227932

  20. The chemical abundance analysis of normal early A- and late B-type stars

    CERN Document Server

    Fossati, L; Bagnulo, S; Alecian, E; Grunhut, J; Kochukhov, O; Wade, G

    2009-01-01

    Modern spectroscopy of early-type stars often aims at studying complex physical phenomena. Comparatively less attention is paid to identifying and studying the "normal" A- and B-type stars and testing how the basic atomic parameters and standard spectral analysis allow one to fit the observations. We wish to stablish whether the chemical composition of the solar photosphere can be regarded as a reference for early A- and late B-type stars. We have obtained optical high-resolution, high signal-to-noise ratio spectra of three slowly rotating early-type stars (HD 145788, 21 Peg and pi Cet) that show no obvious sign of chemical peculiarity, and performed a very accurate LTE abundance analysis of up to 38 ions of 26 elements (for 21 Peg), using a vast amount of spectral lines visible in the spectral region covered by our spectra. We provide an exhaustive description of the abundance characteristics of the three analysed stars with a critical review of the line parameters used to derive the abundances. We compiled ...

  1. Comparison of physicochemical properties of B-type nontraditional starches from different sources.

    Science.gov (United States)

    Huang, Jun; Zhao, Lingxiao; Man, Jianmin; Wang, Juan; Zhou, Weidong; Huai, Huyin; Wei, Cunxu

    2015-01-01

    Starches were isolated from rhizomes of Curcuma longa, Canna edulis and Canna indica and bulbs of Lilium lancifolium, and showed a B-type X-ray diffraction pattern. Their physicochemical properties were investigated and compared. These starches showed significantly different granule morphologies and sizes, but all had eccentric hila. The C. longa starch had the lowest content of amylopectin short branch-chain and branching degree and the highest content of amylopectin long branch-chain, and the L. lancifolium starch the highest content of amylopectin short branch-chain and branching degree and the lowest content of amylopectin long branch-chain among the four starches. The L. lancifolium starch had the lowest resistance to gelatinization, and showed the lowest pasting peak, hot and final viscosities, and the C. longa starch had the highest resistance to gelatinization, and showed the highest pasting hot, final and setback viscosities and the lowest pasting breakdown viscosity. The C. longa and L. lancifolium starches possessed very high and low resistance to hydrolysis and digestion, respectively. The above physicochemical properties would be useful for the applications of B-type starches in food and nonfood industries.

  2. Differential models for B-type open-closed topological Landau-Ginzburg theories

    CERN Document Server

    Babalic, Mirela; Lazaroiu, Calin Iuliu; Tavakol, Mehdi

    2016-01-01

    We propose a family of differential models for B-type open-closed topological Landau-Ginzburg theories defined by a pair $(X,W)$, where $X$ is any non-compact Calabi-Yau manifold and $W$ is any holomorphic complex-valued function defined on $X$ whose critical set is compact. The models are constructed at cochain level using smooth data, including the twisted Dolbeault algebra of polyvector valued forms and a twisted Dolbeault category of holomorphic factorizations of $W$. We give explicit proposals for cochain level versions of the bulk and boundary traces and for the bulk-boundary and boundary-bulk maps of the Landau-Ginzburg theory. We prove that most of the axioms of an open-closed topological field theory are satisfied on cohomology and conjecture that the remaining axioms are also satisfied.

  3. B-Type Natriuretic Peptide: From Posttranslational Processing to Clinical Measurement

    DEFF Research Database (Denmark)

    Goetze, Jens P

    2012-01-01

    BACKGROUND:Plasma cardiac natriuretic peptides and peptide fragments from their molecular precursors are markers of heart disease. Clinical studies have defined the current diagnostic utility of these markers, whereas biochemical elucidation of peptide structure and posttranslational processing has...... revealed new plasma peptide forms of potential clinical use.CONTENT:Natriuretic propeptide structures undergo variable degrees of endo- and exoproteolytic cleavages as well as amino acid modifications, which leave the plasma phase of the peptides highly heterogeneous and dependent on cardiac......-atrial natriuretic peptide and pro-B-type natriuretic peptide are useful plasma markers in heart failure. New data have defined cardiac myocytes as competent endocrine cells in posttranslational processing and cellular secretion....

  4. Bilinear identities for an extended B-type Kadomtsev-Petviashvili hierarchy

    CERN Document Server

    Lin, Runliang; Liu, Xiaojun; Zeng, Yunbo

    2016-01-01

    In this paper, we construct the bilinear identities for the wave functions of an extended B-type Kadomtsev-Petviashvili (BKP) hierarchy, which contains two types of (2+1)-dimensional Sawada-Kotera equation with a self-consistent source (2d-SKwS-I and 2d-SKwS-II). By introducing an auxiliary variable corresponding to the extended flow for the BKP hierarchy, we find the tau-function and the bilinear identities for this extended BKP hierarchy. The bilinear identities can generate all the Hirota's bilinear equations for the zero-curvature forms of this extended BKP hierarchy. As examples, the Hirota's bilinear equations for the two types of 2d-SKwS (both 2d-SKwS-I and 2d-SKwS-II) will be given explicitly.

  5. Two new SB2 binaries with main sequence B-type pulsators in the Kepler field

    Science.gov (United States)

    Papics, P. I.

    2013-06-01

    OB stars are important in the chemistry and evolution of the Universe, but the sample of targets well understood from an asteroseismological point of view is still too limited to provide feedback on the current evolutionary models. Our study extends this sample with two spectroscopic binary systems. Aims. Our goal is to provide orbital solutions, fundamental parameters and abundances from disentangled high-resolution high signal-to-noise spectra, as well as to analyse and interpret the variations in the Kepler light curve of these carefully selected targets. This way we continue our efforts to map the instability strips of β Cep and slowly pulsating B stars using the combination of high-resolution ground-based spectroscopy and uninterrupted space-based photometry. Methods. We fit Keplerian orbits to radial velocities measured from selected absorption lines of high-resolution spectroscopy using synthetic composite spectra to obtain orbital solutions. We use revised masks to obtain optimal light curves from the original pixel-data from the Kepler satellite, which provided better long term stability compared to the pipeline processed light curves. We use various time-series analysis tools to explore and describe the nature of variations present in the light curve. Results. We find two eccentric double-lined spectroscopic binary systems containing a total of three main sequence B-type stars (and one F-type component) of which at least one in each system exhibits light variations. The light curve analysis (combined with spectroscopy) of the system of two B stars points towards the presence of tidally excited g modes in the primary component. We interpret the variations seen in the second system as classical g mode pulsations driven by the κ mechanism in the B type primary, and explain the unexpected power in the p mode region as a result of nonlinear resonant mode excitation.

  6. CIRCUMBINARY PLANETS ORBITING THE RAPIDLY PULSATING SUBDWARF B-TYPE BINARY NY Vir

    Energy Technology Data Exchange (ETDEWEB)

    Qian, S.-B.; Zhu, L.-Y.; Dai, Z.-B.; He, J.-J. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China); Fernandez-Lajus, E. [Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires (Argentina); Xiang, F.-Y., E-mail: qsb@ynao.ac.cn [Physics Department, Xiangtan University, 411105 Xiangtan, Funan Province (China)

    2012-02-15

    We report here the tentative discovery of a Jovian planet in orbit around the rapidly pulsating subdwarf B-type (sdB-type) eclipsing binary NY Vir. By using newly determined eclipse times together with those collected from the literature, we detect that the observed-calculated (O - C) curve of NY Vir shows a small-amplitude cyclic variation with a period of 7.9 yr and a semiamplitude of 6.1 s, while it undergoes a downward parabolic change (revealing a period decrease at a rate of P-dot = -9.2 x 10{sup -12}). The periodic variation was analyzed for the light-travel-time effect via the presence of a third body. The mass of the tertiary companion was determined to be M{sub 3}sin i' = 2.3({+-} 0.3)M{sub Jupiter} when a total mass of 0.60 M{sub Sun} for NY Vir is adopted. This suggests that it is most probably a giant circumbinary planet orbiting NY Vir at a distance of about 3.3 astronomical units (AU). Since the rate of period decrease cannot be explained by true angular momentum loss caused by gravitational radiation or/and magnetic braking, the observed downward parabolic change in the O - C diagram may be only a part of a long-period (longer than 15 years) cyclic variation, which may reveal the presence of another Jovian planet ({approx}2.5 M{sub Jupiter}) in the system.

  7. A two-subunit cytochrome c oxidase (cytochrome aa3) from Paracoccus dentrificans.

    OpenAIRE

    Ludwig, B.; Schatz, G

    1980-01-01

    Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) was purified from the cytoplasmic membrane of the bacterium Paracoccus denitrificans. The enzyme contains two heme groups (a and a3) and two copper atoms per minimal unit, oxidizes mammalian cytochrome c at a high rate, and, when incorporated into liposomes, generates an electrochemical proton gradient during cytochrome c oxidation. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis reveals only two subunits of...

  8. Cytochromes P460 and c'-beta; a new family of high-spin cytochromes c.

    Science.gov (United States)

    Elmore, Bradley O; Bergmann, David J; Klotz, Martin G; Hooper, Alan B

    2007-03-01

    Cytochromes-P460 of Nitrosomonas europaea and Methylococcus capsulatus (Bath), and the cytochrome c' of M. capsulatus, believed to be involved in binding or transformation of N-oxides, are shown to represent an evolutionarily related new family of monoheme, approximately 17kDa, cytochromes c found in the genomes of diverse Proteobacteria. All members of this family have a predicted secondary structure predominantly of beta-sheets in contrast to the predominantly alpha-helical cytochromes c' found in photoheterotrophic and denitrifying Proteobacteria.

  9. Mass spectrometry-based proteomic analysis of human liver cytochrome(s) P450

    Energy Technology Data Exchange (ETDEWEB)

    Shrivas, Kamlesh; Mindaye, Samuel T.; Getie-Kebtie, Melkamu; Alterman, Michail A., E-mail: Michail.Alterman@fda.hhs.gov

    2013-02-15

    The major objective of personalized medicine is to select optimized drug therapies and to a large degree such mission is determined by the expression profiles of cytochrome(s) P450 (CYP). Accordingly, a proteomic case study in personalized medicine is provided by the superfamily of cytochromes P450. Our knowledge about CYP isozyme expression on a protein level is very limited and based exclusively on DNA/mRNA derived data. Such information is not sufficient because transcription and translation events do not lead to correlated levels of expressed proteins. Here we report expression profiles of CYPs in human liver obtained by mass spectrometry (MS)-based proteomic approach. We analyzed 32 samples of human liver microsomes (HLM) of different sexes, ages and ethnicity along with samples of recombinant human CYPs. We have experimentally confirmed that each CYP isozyme can be effectively differentiated by their unique isozyme-specific tryptic peptide(s). Trypsin digestion patterns for almost 30 human CYP isozymes were established. Those findings should assist in selecting tryptic peptides suitable for MS-based quantitation. The data obtained demonstrate remarkable differences in CYP expression profiles. CYP2E1, CYP2C8 and CYP4A11 were the only isozymes found in all HLM samples. Female and pediatric HLM samples revealed much more diverse spectrum of expressed CYPs isozymes compared to male HLM. We have confirmed expression of a number of “rare” CYP (CYP2J2, CYP4B1, CYP4V2, CYP4F3, CYP4F11, CYP8B1, CYP19A1, CYP24A1 and CYP27A1) and obtained first direct experimental data showing expression of such CYPs as CYP2F1, CYP2S1, CYP2W1, CYP4A22, CYP4X1, and CYP26A1 on a protein level. - Highlights: ► First detailed proteomic analysis of CYP isozymes expression in human liver ► Trypsin digestion patterns for almost 30 human CYP isozymes established ► The data obtained demonstrate remarkable differences in CYP expression profiles. ► Female HLM samples revealed more

  10. Utilizing Chemical Genomics to Identify Cytochrome b as a Novel Drug Target for Chagas Disease.

    Directory of Open Access Journals (Sweden)

    Shilpi Khare

    2015-07-01

    Full Text Available Unbiased phenotypic screens enable identification of small molecules that inhibit pathogen growth by unanticipated mechanisms. These small molecules can be used as starting points for drug discovery programs that target such mechanisms. A major challenge of the approach is the identification of the cellular targets. Here we report GNF7686, a small molecule inhibitor of Trypanosoma cruzi, the causative agent of Chagas disease, and identification of cytochrome b as its target. Following discovery of GNF7686 in a parasite growth inhibition high throughput screen, we were able to evolve a GNF7686-resistant culture of T. cruzi epimastigotes. Clones from this culture bore a mutation coding for a substitution of leucine by phenylalanine at amino acid position 197 in cytochrome b. Cytochrome b is a component of complex III (cytochrome bc1 in the mitochondrial electron transport chain and catalyzes the transfer of electrons from ubiquinol to cytochrome c by a mechanism that utilizes two distinct catalytic sites, QN and QP. The L197F mutation is located in the QN site and confers resistance to GNF7686 in both parasite cell growth and biochemical cytochrome b assays. Additionally, the mutant cytochrome b confers resistance to antimycin A, another QN site inhibitor, but not to strobilurin or myxothiazol, which target the QP site. GNF7686 represents a promising starting point for Chagas disease drug discovery as it potently inhibits growth of intracellular T. cruzi amastigotes with a half maximal effective concentration (EC50 of 0.15 µM, and is highly specific for T. cruzi cytochrome b. No effect on the mammalian respiratory chain or mammalian cell proliferation was observed with up to 25 µM of GNF7686. Our approach, which combines T. cruzi chemical genetics with biochemical target validation, can be broadly applied to the discovery of additional novel drug targets and drug leads for Chagas disease.

  11. The cytochrome P450 genesis locus: the origin and evolution of animal cytochrome P450s.

    Science.gov (United States)

    Nelson, David R; Goldstone, Jared V; Stegeman, John J

    2013-02-19

    The neighbourhoods of cytochrome P450 (CYP) genes in deuterostome genomes, as well as those of the cnidarians Nematostella vectensis and Acropora digitifera and the placozoan Trichoplax adhaerens were examined to find clues concerning the evolution of CYP genes in animals. CYP genes created by the 2R whole genome duplications in chordates have been identified. Both microsynteny and macrosynteny were used to identify genes that coexisted near CYP genes in the animal ancestor. We show that all 11 CYP clans began in a common gene environment. The evidence implies the existence of a single locus, which we term the 'cytochrome P450 genesis locus', where one progenitor CYP gene duplicated to create a tandem set of genes that were precursors of the 11 animal CYP clans: CYP Clans 2, 3, 4, 7, 19, 20, 26, 46, 51, 74 and mitochondrial. These early CYP genes existed side by side before the origin of cnidarians, possibly with a few additional genes interspersed. The Hox gene cluster, WNT genes, an NK gene cluster and at least one ARF gene were close neighbours to this original CYP locus. According to this evolutionary scenario, the CYP74 clan originated from animals and not from land plants nor from a common ancestor of plants and animals. The CYP7 and CYP19 families that are chordate-specific belong to CYP clans that seem to have originated in the CYP genesis locus as well, even though this requires many gene losses to explain their current distribution. The approach to uncovering the CYP genesis locus overcomes confounding effects because of gene conversion, sequence divergence, gene birth and death, and opens the way to understanding the biodiversity of CYP genes, families and subfamilies, which in animals has been obscured by more than 600 Myr of evolution.

  12. Electronic and vibrational spectroscopy of the cytochrome c:cytochrome c oxidase complexes from bovine and Paracoccus denitrificans.

    OpenAIRE

    Lynch, S. R.; Copeland, R. A.

    1992-01-01

    The 1:1 complex between horse heart cytochrome c and bovine cytochrome c oxidase, and between yeast cytochrome c and Paracoccus denitrificans cytochrome c oxidase have been studied by a combination of second derivative absorption, circular dichroism (CD), and resonance Raman spectroscopy. The second derivative absorption and CD spectra reveal changes in the electronic transitions of cytochrome a upon complex formation. These results could reflect changes in ground state heme structure or chan...

  13. Cytochrome c1 exhibits two binding sites for cytochrome c in plants.

    Science.gov (United States)

    Moreno-Beltrán, Blas; Díaz-Quintana, Antonio; González-Arzola, Katiuska; Velázquez-Campoy, Adrián; De la Rosa, Miguel A; Díaz-Moreno, Irene

    2014-10-01

    In plants, channeling of cytochrome c molecules between complexes III and IV has been purported to shuttle electrons within the supercomplexes instead of carrying electrons by random diffusion across the intermembrane bulk phase. However, the mode plant cytochrome c behaves inside a supercomplex such as the respirasome, formed by complexes I, III and IV, remains obscure from a structural point of view. Here, we report ab-initio Brownian dynamics calculations and nuclear magnetic resonance-driven docking computations showing two binding sites for plant cytochrome c at the head soluble domain of plant cytochrome c1, namely a non-productive (or distal) site with a long heme-to-heme distance and a functional (or proximal) site with the two heme groups close enough as to allow electron transfer. As inferred from isothermal titration calorimetry experiments, the two binding sites exhibit different equilibrium dissociation constants, for both reduced and oxidized species, that are all within the micromolar range, thus revealing the transient nature of such a respiratory complex. Although the docking of cytochrome c at the distal site occurs at the interface between cytochrome c1 and the Rieske subunit, it is fully compatible with the complex III structure. In our model, the extra distal site in complex III could indeed facilitate the functional cytochrome c channeling towards complex IV by building a "floating boat bridge" of cytochrome c molecules (between complexes III and IV) in plant respirasome.

  14. Improving stellar parameter and abundance determinations of early B-type stars

    CERN Document Server

    Nieva, Maria-Fernanda

    2009-01-01

    In the past years we have made great efforts to reduce the statistical and systematic uncertainties in stellar parameter and chemical abundance determinations of early B-type stars. Both the construction of robust model atoms for non-LTE line-formation calculations and a novel self-consistent spectral analysis methodology were decisive to achieve results of unprecedented precision. They were extensively tested and applied to high-quality spectra of stars from OB associations and the field in the solar neighbourhood, covering a broad parameter range. Initially, most lines of hydrogen, helium and carbon in the optical/near-IR spectral range were reproduced simultaneously in a consistent way for the first time, improving drastically on the accuracy of results in published work.By taking additional ionization equilibria of oxygen, neon, silicon and iron into account, uncertainties as low as ~1% in effective temperature, ~10% in surface gravity and ~20% in elemental abundances are achieved - compared to ~5-10%, ~2...

  15. Pulsating B-type stars in the open cluster NGC 884: frequencies, mode identification and asteroseismology

    CERN Document Server

    Saesen, S; Aerts, C; Miglio, A; Carrier, F

    2013-01-01

    Recent progress in the seismic interpretation of field beta Cep stars has resulted in improvements of the physics in the stellar structure and evolution models of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition. We present an observational asteroseismology study based on the discovery of numerous multi-periodic and mono-periodic B-stars in the open cluster NGC 884. We describe a thorough investigation of the pulsational properties of all B-type stars in the cluster. Overall, our detailed frequency analysis resulted in 115 detected frequencies in 65 stars. We found 36 mono-periodic, 16 bi-periodic, 10 tri-periodic, and 2 quadru-periodic stars and one star with 9 independent frequencies. We also derived the amplitudes and phases of all detected frequencies in the U, B, V and I filter, if available. We achieved unambiguous identifications of the mode degree for twelve of the de...

  16. Discovery of a magnetic field in the early B-type star sigma Lupi

    CERN Document Server

    Henrichs, H F; Plaggenborg, B; Marsden, S C; Waite, I A; Landstreet, J D; Wade, G A; Grunhut, J H; Oksala, M E

    2012-01-01

    Magnetic early B-type stars are rare. To identify them, we use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of UV stellar wind lines occurring symmetric about the approximate rest wavelength. Probable magnetic candidates are targets for follow-up spectropolarimetry to search for a magnetic field. From the UV wind line variability the B1/B2V star sigma Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the Least-Squares Deconvolution method. The UV line variations of sigma Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The EW variations of the UV lines, the magnetic and ...

  17. Emergent criticality in complex turing B-type atomic switch networks.

    Science.gov (United States)

    Stieg, Adam Z; Avizienis, Audrius V; Sillin, Henry O; Martin-Olmos, Cristina; Aono, Masakazu; Gimzewski, James K

    2012-01-10

    Recent advances in the neuromorphic operation of atomic switches as individual synapse-like devices demonstrate the ability to process information with both short-term and long-term memorization in a single two terminal junction. Here it is shown that atomic switches can be self-assembled within a highly interconnected network of silver nanowires similar in structure to Turing’s “B-Type unorganized machine”, originally proposed as a randomly connected network of NAND logic gates. In these experimental embodiments,complex networks of coupled atomic switches exhibit emergent criticality similar in nature to previously reported electrical activity of biological brains and neuron assemblies. Rapid fluctuations in electrical conductance display metastability and power law scaling of temporal correlation lengths that are attributed to dynamic reorganization of the interconnected electro-ionic network resulting from induced non-equilibrium thermodynamic instabilities. These collective properties indicate a potential utility for realtime,multi-input processing of distributed sensory data through reservoir computation. We propose these highly coupled, nonlinear electronic networks as an implementable hardware-based platform toward the creation of physically intelligent machines.

  18. Endothelial Expression of Scavenger Receptor Class B, Type I Protects against Development of Atherosclerosis in Mice

    Directory of Open Access Journals (Sweden)

    Boris L. Vaisman

    2015-01-01

    Full Text Available The role of scavenger receptor class B, type I (SR-BI in endothelial cells (EC was examined in several novel transgenic mouse models expressing SR-BI in endothelium of mice with normal C57Bl6/N, apoE-KO, or Scarb1-KO backgrounds. Mice were also created expressing SR-BI exclusively in endothelium and liver. Endothelial expression of the Tie2-Scarb1 transgene had no significant effect on plasma lipoprotein levels in mice on a normal chow diet but on an atherogenic diet, significantly decreased plasma cholesterol levels, increased plasma HDL cholesterol (HDL-C levels, and protected mice against atherosclerosis. In 8-month-old apoE-KO mice fed a normal chow diet, the Tie2-Scarb1 transgene decreased aortic lesions by 24%. Mice expressing SR-BI only in EC and liver had a 1.5 ± 0.1-fold increase in plasma cholesterol compared to mice synthesizing SR-BI only in liver. This elevation was due mostly to increased HDL-C. In EC culture studies, SR-BI was found to be present in both basolateral and apical membranes but greater cellular uptake of cholesterol from HDL was found in the basolateral compartment. In summary, enhanced expression of SR-BI in EC resulted in a less atherogenic lipoprotein profile and decreased atherosclerosis, suggesting a possible role for endothelial SR-BI in the flux of cholesterol across EC.

  19. The nature of the late B-type stars HD 67044 and HD 42035

    CERN Document Server

    Monier, R; Royer, F

    2016-01-01

    While monitoring a sample of apparently slowly rotating superficially normal bright late B and early A stars in the northern hemisphere, we have discovered that HD 67044 and HD 42035, hitherto classified as normal late B-type stars, are actually respectively a new chemically peculiar star and a new spectroscopic binary containing a very slow rotator HD 42035 S with ultra-sharp lines (vsini = 3.7 km/s) and a fast rotator HD 42035 B with broad lines. The lines of Ti, Cr, Mn, Sr, Y, Zr and Ba are conspicuous features in the high resolution SOPHIE spectrum of HD 67044. The HgII line at 3983.93 A is also present as a weak feature. The composite spectrum of HD 42035 is characterised by very sharp lines formed in HD 42035 S superimposed onto the shallow and broad lines of HD 42035 B. These very sharp lines are mostly due to light elements from C to Ni, the only heavy species definitely present are Sr and Ba. Selected lines of 21 chemical elements from He up to Hg have been synthesized using model atmospheres compute...

  20. Solids flow diagram of a CFB riser using Geldart B-type powders

    Institute of Scientific and Technical Information of China (English)

    Shiva Mahmoudi; Chian Wen Chan; Anke Brems; Jonathan Seville; Jan Baeyens

    2012-01-01

    Riser operating modes are vital to designing a circulating fluidized bed (CFB) reactor for a required process of either a gas-solid or a gas-catalytic nature.Different operating modes provide different solids' residence times and mixing behaviors,which define the reactions' efficiency and yield.The literature demonstrates distinct operating modes resulting from observed differences in slip factors and the range of particle velocities and their associated residence time distribution.The present research uses positron emission particle tracking (PEPT) in a riser of B-type bed material to determine the different operating modes by measuring (i) particle velocities and residence time distribution,(ii) population densities of these particles in the cross-sectional area of the riser,and (iii) solids flow pattern at the bottom of the riser.Data treatment defines four distinct solids hold-up regimes in the riser and proposes a “phase diagram” depicting the existence of the different operating modes (dilute,dense,core-annulus and combined) as a function of the superficial gas velocity and solids circulation flux in the riser.The delineated regimes have good agreement with available literature data and known industrial operations.Comparison with literature data for risers using A-type powders is also fair.The diagram enables CFB designers to better delineate operating characteristics.

  1. Cortical Brain Connectivity and B-Type Natriuretic Peptide in Patients With Congestive Heart Failure.

    Science.gov (United States)

    Vecchio, Fabrizio; Miraglia, Francesca; Valeriani, Lavinia; Scarpellini, Maria Gabriella; Bramanti, Placido; Mecarelli, Oriano; Rossini, Paolo M

    2015-07-01

    The brain has a high level of complexity and needs continuous oxygen supply. So it is clear that any pathological condition, or physiological (aging) change, in the cardiovascular system affects functioning of the central nervous system. We evaluated linear aspects of the relationship between the slowness of cortical rhythms, as revealed by the modulation of a graph connectivity parameter, and congestive heart failure (CHF), as a reflection of neurodegenerative processes. Eyes-closed resting electroencephalographic (EEG) data of 10 patients with CHF were recorded by 19 electrodes positioned according the international 10-20 system. Graph theory function (normalized characteristic path length λ) was applied to the undirected and weighted networks obtained by lagged linear coherence evaluated by eLORETA software, therefore getting rid of volumetric propagation influences. The EEG frequency bands of interest were: delta (2-4 Hz), theta (4-8 Hz), alpha 1 (8-10.5 Hz), alpha 2 (10.5-13 Hz), beta 1 (13-20 Hz), beta 2 (20-30 Hz), and gamma (30-40 Hz). The analysis between B-type natriuretic peptide (BNP) values and λ showed positive correlation in delta, associated with a negative correlation in alpha 2 band. Namely, the higher the severity of the disease (as revealed by the BNP vales), the higher the λ in delta, and lower in alpha 2 band. Results suggest that delta and alpha λ indices are good markers of the severity of CHF.

  2. WW Geminorum: An early B-type eclipsing binary evolving into the contact phase

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.-G.; Dai, H.-F.; Yin, X.-G. [School of Physics and Electronic Information, Huaibei Normal University, 235000 Huaibei, Anhui Province (China); Yang, Y., E-mail: yygcn@163.com, E-mail: yangyg@chnu.edu.cn, E-mail: yangy818@yeah.net [Department of Electronic Engineering, School of Information Science Technology, East China Normal University, 200241 Shanghai (China)

    2014-11-01

    WW Gem is a B-type eclipsing binary with a period of 1.2378 days. The CCD photometry of this binary was performed in 2013 December using the 85 cm telescope at the Xinglong Stations of the National Astronomical Observatories of China. Using the updated W-D program, the photometric model was deduced from the VRI light curves. The results imply that WW Gem is a near-contact eclipsing binary whose primary component almost fills its Roche lobe. The photometric mass ratio is q {sub ph} = 0.48(± 0.05). All collected times of minimum light, including two new ones, were used for the period studies. The orbital period changes of WW Gem could be described by an upward parabola, possibly overlaid by a light-time orbit with a period of P {sub mod} = 7.41(± 0.04) yr and a semi-amplitude of A = 0.0079 days(± 0.0005 days), respectively. This kind of cyclic oscillation may be attributed to the light-travel time effect via the third body. The long-term period increases at a rate of dP/dt = +3.47(±0.04) × 10{sup –8} day yr{sup –1}, which may be explained by the conserved mass transfer from the less massive component to the more massive one. With mass transfer, the massive binary WW Gem may be evolving into a contact binary.

  3. Oxygen abundance determination of B-type stars with the OI 7771-5A lines

    CERN Document Server

    Takeda, Yoichi

    2016-01-01

    Oxygen abundances of 34 B-type stars in the effective temperature range of Teff~10000-28000K with diversified rotational velocities (vesini~ 0-250km/s) were determined from the OI triplet lines at 7771-5A, with an aim to examine whether this OI feature can be a reliable abundance indicator for such high-temperature stars including rapid rotators. It revealed that the required non-LTE abundance correction is distinctly large (ranging from ~-0.6dex to ~-1.7dex) and its consideration is indispensable. On the condition that the non-LTE effect is taken into account, this triplet is a useful O abundance indicator (with a precision of ~200mA). In contrast, it is not adequate for abundance derivation for stars at Teff >~25000K, where its strength rapidly drops down toward a hardly detectable level (except for sharp-lined stars) and its sensitivity to Teff or log g becomes considerably large. The resulting non-LTE oxygen abundances turned out to be almost normal (i.e., near-solar around ~8.7-8.8 within +/-~0.2dex) for...

  4. B-type natriuretic peptide modulates ghrelin, hunger, and satiety in healthy men.

    Science.gov (United States)

    Vila, Greisa; Grimm, Gabriele; Resl, Michael; Heinisch, Birgit; Einwallner, Elisa; Esterbauer, Harald; Dieplinger, Benjamin; Mueller, Thomas; Luger, Anton; Clodi, Martin

    2012-10-01

    Chronic heart failure is accompanied by anorexia and increased release of B-type natriuretic peptide (BNP) from ventricular cardiomyocytes. The pathophysiological mechanisms linking heart failure and appetite regulation remain unknown. In this study, we investigated the impact of intravenous BNP administration on appetite-regulating hormones and subjective ratings of hunger and satiety in 10 healthy volunteers. Participants received in a randomized, placebo-controlled, crossover, single-blinded study (subject) placebo once and 3.0 pmol/kg/min human BNP-32 once administered as a continuous infusion during 4 h. Circulating concentrations of appetite-regulating peptides were measured hourly. Subjective ratings of hunger and satiety were evaluated by visual analog scales. BNP inhibited the fasting-induced increase in total and acylated ghrelin concentrations over time (P = 0.043 and P = 0.038, respectively). In addition, BNP decreased the subjective rating of hunger (P = 0.009) and increased the feeling of satiety (P = 0.012) when compared with placebo. There were no significant changes in circulating peptide YY, glucagon-like peptide 1, oxyntomodulin, pancreatic polypeptide, leptin, and adiponectin concentrations. In summary, our results demonstrate that BNP exerts anorectic effects and reduces ghrelin concentrations in men. These data, taken together with the known cardiovascular properties of ghrelin, support the existence of a heart-gut-brain axis, which could be therapeutically targeted in patients with heart failure and obesity.

  5. HE 0437-5439 -- an unbound hyper-velocity main-sequence B-type star

    CERN Document Server

    Edelmann, H; Heber, U; Christlieb, N; Reimers, D; Edelmann, Heinz; Napiwotzki, Ralf; Heber, Uli; Christlieb, Norbert; Reimers, Dieter

    2005-01-01

    We report the discovery of a 16th magnitude star, HE0437-5439, with a heliocentric radial velocity of +723+-3km/s. A quantitative spectral analysis of high-resolution optical spectra obtained with the VLT and the UVES spectrograph shows that HE0437-5439 is a main sequence B-type star with Teff=20350K, log g=3.77, solar within a factor of a few helium abundance and metal content, rotating at v sin i=54km/s. Using appropriate evolutionary tracks we derive a mass of 8 Msun and a corresponding distance of 61 kpc. Its galactic rest frame velocity is at least 563km/s, almost twice the local Galactic escape velocity, indicating that the star is unbound to the Galaxy. Numerical kinematical experiments are carried out to constrain its place of birth. It has been suggested that such hyper-velocity stars can be formed by the tidal disruption of a binary through interaction with the super-massive black hole at the Galactic center (GC). HE0437-5439 needs about 100Myrs to travel from the GC to its presentposition, much lon...

  6. Analysis of mammalian cytochrome P450 structure and function by site-directed mutagenesis.

    Science.gov (United States)

    Domanski, T L; Halpert, J R

    2001-06-01

    Over the past decade, site-directed mutagenesis has become an essential tool in the study of mammalian cytochrome P450 structure-function relationships. Residues affecting substrate specificity, cooperativity, membrane localization, and interactions with redox partners have been identified using a combination of amino-acid sequence alignments, homology modeling, chimeragenesis, and site-directed mutagenesis. As homology modeling and substrate docking technology continue to improve, the ability to predict more precise functions for specific residues will also advance, making it possible to utilize site-directed mutagenesis to test these predictions. Future studies will employ site-directed mutagenesis to learn more about cytochrome P450 substrate access channels, to define the role of residues that do not lie within substrate recognition sites, to engineer additional soluble forms of microsomal cytochromes P450 for x-ray crystallography, and to engineer more efficient enzymes for drug activation and/or bioremediation.

  7. Fast prediction of cytochrome P450 mediated drug metabolism

    DEFF Research Database (Denmark)

    Rydberg, Patrik Åke Anders; Poongavanam, Vasanthanathan; Oostenbrink, Chris

    2009-01-01

    Cytochrome P450 mediated metabolism of drugs is one of the major determinants of their kinetic profile, and prediction of this metabolism is therefore highly relevant during the drug discovery and development process. A new rule-based method, based on results from density functional theory...... % of substrates for a set of 20 substrates. In combination with docking, it can predict isoform-specific metabolism, and we apply this on CYP1A2 with very good results on 81 substrates, for which we find a major metabolite ranked in the top three for 90 % of the substrates (100 % in the training set and 87...

  8. Cytochrome b5 from Giardia lamblia.

    Science.gov (United States)

    Alam, Samiah; Yee, Janet; Couture, Manon; Takayama, Shin-ichi J; Tseng, Wan-Hsin; Mauk, A Grant; Rafferty, Steven

    2012-12-01

    The protozoan intestinal parasite Giardia lamblia lacks mitochondria and the ability to make haem yet encodes several putative haem-binding proteins, including three of the cytochrome b(5) family. We cloned one of these (gCYTb5-I) and expressed it within Escherichia coli as a soluble holoprotein. UV-visible and resonance Raman spectra of gCYTb5-I resemble those of microsomal cytochrome b(5), and homology modelling supports a structure in which a pair of invariant histidine residues act as axial ligands to the haem iron. The reduction potential of gCYTb5-I is -165 mV vs. SHE and is relatively low compared to most values (-110 to +80 mV) for this class of protein. The amino- and carboxy-terminal sequences that flank the central haem-binding core of the Giardia cytochromes are highly charged and differ from those of other family members. A core gCYTb5-I variant lacking these flanking sequences was also able to bind haem. The presence of one actual and two probable functional cytochromes b(5) in Giardia is evidence of uncharacterized cytochrome-mediated metabolic processes within this medically important protist.

  9. B-type natriuretic peptide (BNP serum levels in rats after forced repeated swimming stress

    Directory of Open Access Journals (Sweden)

    Almira Hadžovic-Džuvo

    2011-02-01

    Full Text Available Aim To estimate the effects of forced repeated swimming stress on BNP serum levels in rats. Methods Adult male Wistar rats weighting between 280-330 g were divided into two groups: control group (n =8 and stress group (n =8. Rats in the stress group were exposed to forced swimming stress daily, for 7 days. The rats were forced to swim in plastic tanks (90 cm wide, 120 cm deep containing tap water (temperature ca. 25°C. The depth of water was 40 cm. Duration of each swimming session progressively increased from 10 minutes on the irst day to 40 minutes on days 6 and 7. Rats were sacriiced and blood was drawn from abdominal aorta for BNP analysis immediately after the last swimming session. B-type natriuretic serum level was determined by ELISA method using RAT BNP-32 kit (Phoenix Pharmaceutical Inc.. Results There was no statistically signiicant difference between mean BNP serum level in the stress group after the swimming period (0.81±0.14 ng/ml as compared to the unstressed group of rats (0.8 ±0.08ng/ml. After the swimming period mean body weight slightly decreased in the stress group in comparison with values before stress period (296.3 g vs.272.8 g, but this difference was not statistically signiicant. The stress period had no inluence on food intake in the stress rat group. Conclusion The workload consisting of 40-minutes long swimming session is not suficient to provoke BNP release from myocardium in rats.

  10. Hepatocellular carcinoma with chronic B-type hepatitis complicated by autoimmune hemolytic anemia: A case report

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A 57-year-old man consulted a local hospital because of a persistent slight fever. At the age of 37 years he was diagnosed having B-type hepatitis, but left the liver dysfunction untreated. Twenty years later, he was diagnosed having chronic hepatitis B, hepatocellular carcinoma (HCC) and macrocytic anemia, and referred to our hospital for further investigation. A HCC with a maximum diameter of 5.2 cm was detected in segment 8. Results of blood tests included 1.8 mg/dL serum total bilirubin, 0.9 mg/dL bilirubin, less than 10 mg/dL haptoglobin, 7.9 g/dL hemoglobin, 130 fL MCV, and 14.5% reticulocytes. A bone marrow sample showed erythroid hyperplasia. The direct Coombs test gave a positive result. We diagnosed the anemia as autoimmmune hemolytic anemia (AIHA), for which prednisolone could not be administered due to positivity for HBsAg and HBeAg. After preparation of washed blood cells for later transfusion, the patient underwent systematic resection of segment 8. The cut surface of the resected specimen demonstrated an encapsulated yellow-brownish tumor measuring 52 mm × 40 mmwhich was diagnosed pathologicaly as moderately differentiated HCC. On the 9th postoperative day, the patient's temperature rose to 38℃, and exacerbated hemolysis was observed. The maximum total bilirubin value was 5.8 mg/dL and minimum hemoglobin level was 4.6 g/dL. He tolerated this period without blood transfusion. Currently he is being followed up as an outpatient, and shows no signs of HCC recurrence or symptoms of anemia. AIHA associated with HBV infection has been described in only three previous cases, and the present case is the first in which surgery was performed for accompanying HCC.

  11. Two-dimensional crystallization of monomeric bovine cytochrome c oxidase with bound cytochrome c in reconstituted lipid membranes.

    Science.gov (United States)

    Osuda, Yukiho; Shinzawa-Itoh, Kyoko; Tani, Kazutoshi; Maeda, Shintaro; Yoshikawa, Shinya; Tsukihara, Tomitake; Gerle, Christoph

    2016-06-01

    Mitochondrial cytochrome c oxidase utilizes electrons provided by cytochrome c for the active vectorial transport of protons across the inner mitochondrial membrane through the reduction of molecular oxygen to water. Direct structural evidence on the transient cytochrome c oxidase-cytochrome c complex thus far, however, remains elusive and its physiological relevant oligomeric form is unclear. Here, we report on the 2D crystallization of monomeric bovine cytochrome c oxidase with tightly bound cytochrome c at a molar ratio of 1:1 in reconstituted lipid membranes at the basic pH of 8.5 and low ionic strength.

  12. Nerval influences on liver cytochrome P450.

    Science.gov (United States)

    Klinger, W; Karge, E; Danz, M; Krug, M

    1995-09-01

    In male young adult Wistar rats the influences of nucleus raphe electrocoagulation, spinal cord dissection (cordotomy between C7 and Th1), vagotomy and denervation of liver hilus by phenol on liver cytochrome P450-system (cytochrome P450 concentration, ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities, hexobarbitone sleeping time) were investigated. In general the influences were small or negligible when compared with sham operated controls, only after vagotomy the depressing effect of sham operation was abolished. In all cases sham operation had a depressing effect until up to five weeks after operation.

  13. Flower colour and cytochromes P450†

    OpenAIRE

    Tanaka, Yoshikazu; Brugliera, Filippa

    2013-01-01

    Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′,5′-hydroxylase (F3′5′H) and thus they play a crucial role ...

  14. Genetic characterization of Bagarius species using cytochrome c oxidase I and cytochrome b genes.

    Science.gov (United States)

    Nagarajan, Muniyandi; Raja, Manikam; Vikram, Potnuru

    2016-09-01

    In this study, we first inferred the genetic variability of two Bagarius bagarius populations collected from Ganges and Brahmaputra rivers of India using two mtDNA markers. Sequence analysis of COI gene did not show significant differences between two populations whereas cytochrome b gene showed significant differences between two populations. Followed by, genetic relationship of B. bagarius and B. yarrielli was analyzed using COI and cytochrome b gene and the results showed a higher level genetic variation between two species. The present study provides support for the suitability of COI and cytochrome b genes for the identification of B. bagarius and B. yarrielli.

  15. Molecular cloning, genomic organization, and expression of a B-type (cricket-type) allatostatin preprohormone from Drosophila melanogaster

    DEFF Research Database (Denmark)

    Williamson, M; Lenz, C; Winther, A M

    2001-01-01

    and nonamidated C terminus. We have previously reported the structure of an A-type allatostatin preprohormone from the fruitfly Drosophila melanogaster. Here we describe the molecular cloning of a B-type prepro-allatostatin from Drosophila (DAP-B). DAP-B is 211 amino acid residues long and contains one copy each...

  16. Will sacubitril-valsartan diminish the clinical utility of B-type natriuretic peptide testing in acute cardiac care?

    DEFF Research Database (Denmark)

    Mair, Johannes; Lindahl, Bertil; Giannitsis, Evangelos;

    2016-01-01

    Since the approval of sacubitril-valsartan for the treatment of chronic heart failure with reduced ejection fraction, a commonly raised suspicion is that a wider clinical use of this new drug may diminish the clinical utility of B-type natriuretic peptide testing as sacubitril may interfere with B...

  17. Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens Oscar; Kjær, Andreas;

    2010-01-01

    Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...

  18. Strategies toward the Total Synthesis of Calyciphylline B-type Alkaloids: A Computational Perspective Aided by DFT Analysis.

    Science.gov (United States)

    Chattopadhyay, Amit Kumar; Berger, Gilles; Hanessian, Stephen

    2016-06-17

    Herein we describe synthetic efforts toward the total synthesis of calyciphylline B-type alkaloids. In the process, we disclose a detailed DFT study of equilibrium geometries and transition states that explains the stereochemical outcome during the formation of critical intermediates. X-ray crystallographic analysis reveals interesting conformational features in the naturally occurring deoxycalyciphylline B and its synthetic congeners.

  19. N-terminal pro-B-type natriuretic peptide as a marker of blunt cardiac contusion in trauma.

    Science.gov (United States)

    Dogan, Halil; Sarikaya, Sezgin; Neijmann, Sebnem Tekin; Uysal, Emin; Yucel, Neslihan; Ozucelik, Dogac Niyazi; Okuturlar, Yıldız; Solak, Suleyman; Sever, Nurten; Ayan, Cem

    2015-01-01

    Cardiac contusion is usually caused by blunt chest trauma and, although it is potentially a life-threatening condition, the diagnosis of a myocardial contusion is difficult because of non-specific symptoms and the lack of an ideal test to detect myocardial damage. Cardiac enzymes, such as creatine kinase (CK), creatine kinase MB fraction (CK-MB), cardiac troponin I (cTn-I), and cardiac troponin T (cTn-T) were used in previous studies to demonstrate the blunt cardiac contusion (BCC). Each of these diagnostic tests alone is not effective for diagnosis of BCC. The aim of this study was to investigate the serum heart-type fatty acid binding protein (h-FABP), N-terminal pro-B-type natriuretic peptide (NT-proBNP), CK, CK-MB, and cTn-I levels as a marker of BCC in blunt chest trauma in rats. The eighteen Wistar albino rats were randomly allocated to two groups; group I (control) (n=8) and group II (blunt chest trauma) (n=10). Isolated BCC was induced by the method described by Raghavendran et al. (2005). All rats were observed in their cages and blood samples were collected after five hours of trauma for the analysis of serum h-FABP, NT-pro BNP, CK, CK-MB, and cTn-I levels. The mean serum NT-pro BNP was significantly different between group I and II (10.3 ± 2.10 ng/L versus 15.4 ± 3.68 ng/L, respectively; P=0.0001). NT-pro BNP level >13 ng/ml had a sensitivity of 87.5%, a specificity of 70%, a positive predictive value of 70%, and a negative predictive value of 87.5% for predicting blunt chest trauma (area under curve was 0.794 and P=0.037). There was no significant difference between two groups in serum h-FABP, CK, CK-MB and c Tn-I levels. A relation between NT-Pro BNP and BCC was shown in this study. Serum NT-proBNP levels significantly increased with BCC after 5 hours of the blunt chest trauma. The use of NT-proBNP as an adjunct to other diagnostic tests, such as troponins, electrocardiography (ECG), chest x-ray and echocardiogram may be beneficial for diagnosis of

  20. Modification of the spectral properties of cytochrome b in mutants of Saccharomyces cerevisiae resistant to 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Mapping at two distinct genetic loci of the split mitochondrial gene of cytochrome b.

    Science.gov (United States)

    Briquet, M; Goffeau, A

    1981-07-01

    The effects of five inhibitors of the cytochrome bc1 complex: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), 2-n-heptyl-4-hydroxyquinoline-N-oxide (HpHOQnO), antimycin A, funiculosin and mucidin were measured in submitochondrial particles of strains of the yeast Saccharomyces cerevisiae belonging to two classes of diuron-resistant mutants Diu 1 and Diu 2 which are modified in different exons of the split mitochondrial gene of cytochrome b. 1. The oxidation of NADH and of cytochrome b-561 exhibits a similar resistance to diuron and HpHOQnO in Diu 1 and Diu 2 mutants. 2. No extra reduction of cytochrome b-561 and cytochrome b-565 is observed in the presence of diuron and HpHOQnO. 3. Both Diu 1 and Diu 2 mutants exhibit the red shift of cytochrome b-561 induced by concentrations of HpHOQno 2 -- 3-times higher than those required in the parental strains. 4. The spectral and respiratory effects of antimycin A, funiculosin and mucidin and generally similar in the diuron-resistant mutants and in their parental strains. However a cross-resistance between diuron and antimycin A is indicated in one Diu 2 mutant. 5. From the combined genetic and biochemical data it is concluded that the interaction of diuron and HpHOQnO with cytochrome b is mediated by at least two specific amino acids located apart in the central region of the apocytochrome b peptide coded by mitochondrial DNA. These two amino acids control tightly the extra reduction of cytochromes b-565 and b-561 as well as the flow of electrons through the bc1 complex. However the binding of HpHOQnO required for the expression of the red shift of cytochrome b-561 is only slightly affected by the diu-1 and diu-2 mutations.

  1. Factors Associated with Serum B-Type Natriuretic Peptide in Infants with Single Ventricles

    Science.gov (United States)

    Butts, Ryan J.; Zak, Victor; Hsu, Daphne; Cnota, James; Colan, Steven D.; Hehir, David; Kantor, Paul; Levine, Jami C.; Margossian, Renee; Richmond, Marc; Szwast, Anita; Williams, Derek; Williams, Richard; Atz, Andrew M.

    2014-01-01

    Background Data regarding the value of B-type natriuretic peptide measurements (BNP) in infants with single ventricle (SV) physiology are lacking. The objective of this analysis was to describe the changes in BNP in infants with SV physiology before and after superior cavopulmonary connection (SCPC) surgery. Methods BNP levels were measured by a core laboratory pre-SCPC (5.0 ± 1.6 months) and at age 14 months during a multicenter trial of angiotensin converting enzyme inhibition therapy in infants with SV. Multivariable longitudinal analysis was utilized to model the associations between BNP with three sets of grouped variables (echocardiographic, catheterization, growth). Multivariable analysis was performed to assess associations with patient characteristics at both visits. Associations between BNP and neurodevelopmental variables were investigated at the 14 month visit as neurodevelopmental assessment was performed only at this visit. Results BNP was significantly higher before SCPC (n=173) than at 14 months (n=134); median [IQR] 80.8 pg/ml [35–187] v. 34.5 pg/ml [17–67], p 100 pg/ml was present in 72 (42%) subjects pre-SCPC and 21 (16%) at 14 months. In the 117 patients who had BNP at both visits, the median BNP decreased 32 pg/mL [1–79 pg/mL], p<0.01. In longitudinal multivariable analysis, higher BNP were associated with a higher end-systolic volume z-score (p=0.01), greater degree of atrioventricular (AV) valve regurgitation (p<0.01), lower weight z-score (p<0.01), and lower length z-score (p=0.02) In multivariable analyses, higher BNP at 14 months was associated with presence of arrhythmia post-SCPC surgery (p<0.01), prior Norwood procedure (p<0.01), longer length of hospital stay post-SCPC surgery (p=0.04), and lower Bayley Psychomotor Developmental Index (p=0.02). Conclusion BNP decreases in infants with SV from the pre- SCPC visit to 14 months. Higher BNP is associated with increased ventricular dilation in systole, increased AV valve

  2. Affinity chromatography purification of cytochrome c binding enzymes.

    OpenAIRE

    Azzi, A; Bill, K; Broger, C

    1982-01-01

    An efficient affinity chromatography procedure for the isolation of mitochondrial cytochrome c oxidase and reductase is described. Saccharomyces cerevisiae cytochrome c was used as a ligand, bound to a thiol-Sepharose 4B gel through cysteine-107. In this way, the site of interaction of cytochrome c with cytochrome oxidase and reductase remained unmodified and available for binding to a number of partner enzymes. The procedure is adequate for the purification of all those proteins having in co...

  3. Dimer interface of bovine cytochrome c oxidase is influenced by local posttranslational modifications and lipid binding.

    Science.gov (United States)

    Liko, Idlir; Degiacomi, Matteo T; Mohammed, Shabaz; Yoshikawa, Shinya; Schmidt, Carla; Robinson, Carol V

    2016-07-19

    Bovine cytochrome c oxidase is an integral membrane protein complex comprising 13 protein subunits and associated lipids. Dimerization of the complex has been proposed; however, definitive evidence for the dimer is lacking. We used advanced mass spectrometry methods to investigate the oligomeric state of cytochrome c oxidase and the potential role of lipids and posttranslational modifications in its subunit interfaces. Mass spectrometry of the intact protein complex revealed that both the monomer and the dimer are stabilized by large lipid entities. We identified these lipid species from the purified protein complex, thus implying that they interact specifically with the enzyme. We further identified phosphorylation and acetylation sites of cytochrome c oxidase, located in the peripheral subunits and in the dimer interface, respectively. Comparing our phosphorylation and acetylation sites with those found in previous studies of bovine, mouse, rat, and human cytochrome c oxidase, we found that whereas some acetylation sites within the dimer interface are conserved, suggesting a role for regulation and stabilization of the dimer, phosphorylation sites were less conserved and more transient. Our results therefore provide insights into the locations and interactions of lipids with acetylated residues within the dimer interface of this enzyme, and thereby contribute to a better understanding of its structure in the natural membrane. Moreover dimeric cytochrome c oxidase, comprising 20 transmembrane, six extramembrane subunits, and associated lipids, represents the largest integral membrane protein complex that has been transferred via electrospray intact into the gas phase of a mass spectrometer, representing a significant technological advance.

  4. Cytochrome P450-mediated hepatic metabolism of new fluorescent substrates in cats and dogs.

    NARCIS (Netherlands)

    van Beusekom, C.D.; Schipper, L.; Fink-Gremmels, J.

    2010-01-01

    This study aimed to investigate the biotransformation of cat liver microsomes in comparison to dogs and humans using a high throughput method with fluorescent substrates and classical inhibitors specific for certain isozymes of the human cytochrome P450 (CYP) enzyme family. The metabolic activities

  5. Sequential unfolding of the two-domain protein Pseudomonas stutzeri cytochrome c(4)

    DEFF Research Database (Denmark)

    Andersen, Niels Højmark; Jensen, Thomas Jon; Nørgaard, Allan;

    2002-01-01

    F stutzeri cytochrome c. is a di-haem protein, composed of two globular domains each with His-Met coordinated haem. and a hydrogen bond network between the domains. The domain foldings are highly symmetric but with specific differences including structural differences of ligand coordination, and ...

  6. A Novel Redox State Heme a Marker in Cytochrome c Oxidase Revealed by Raman Spectroscopy

    Science.gov (United States)

    Piccoli, C.; Perna, G.; Scrima, R.; Cela, O.; Rinaldi, R.; Boffoli, D.; Capozzi, V.; Capitanio, N.

    2005-01-01

    This study was aimed to characterize by Raman spectroscopy (excitation line 633 nm) different redox states of the mitochondrial cytochrome c oxidase. The results obtained from a systematic analysis carried out on the mitochondrial enzyme prepared under redox conditions, differently affecting the valence state of the metal prosthetic groups, and a comparison with homologous bacterial heme-copper oxidases, cytochrome c and pyridine hemo-chrome extract revealed a novel redox state marker specifically linked to the redox transition of heme a, peaking at 1645 cm-1, and tentatively assigned to the C=C and/or C=N streching mode of the imidazole ring of a proxymal histidine ligand. The possible involvment of this redox-linked conformational change in the catalytic activity of cytochrome oxidase is discussed.

  7. RNA fragments mimicking tRNA analogs interact with cytochrome c.

    Science.gov (United States)

    Pawlowska, Roza; Janicka, Magdalena; Jedrzejczyk, Dominika; Chworos, Arkadiusz

    2016-04-01

    In times, when drug seeking assays focus on the natural molecular triggers and their analogs, a deeper insight into molecular mechanisms governing the initial step of intrinsic apoptosis (cytochrome c release) is essential to suppress the immortality of pathologically changed cells. In this study, we examined RNA molecules mimicking mitochondrial tRNAs interacting with cytochrome c and possibly affecting its cellular function. tRNA analogs were designed and synthesized prior to the conformational analysis and gel assays clearly stating the nucleic acid-protein complex formation. The circular dichroism spectroscopic (CD) and microscale thermophoresis examination revealed the structural and conformational differences between four tRNA analogs in their interactions with cytochrome c. Obtained CD spectra and gel studies resulted in the complex ratio estimation and conclusion that not only the complex formation may be preferential towards specific tRNAs present in the cell, but nucleobase modifications are not essential for such interaction.

  8. Light-driven cytochrome P450 hydroxylations

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Jensen, Poul Erik; Møller, Birger Lindberg

    2011-01-01

    Plants are light-driven "green" factories able to synthesize more than 200,000 different bioactive natural products, many of which are high-value products used as drugs (e.g., artemisinin, taxol, and thapsigargin). In the formation of natural products, cytochrome P450 (P450) monooxygenases play...

  9. Vectorially oriented monolayers of the cytochrome c/cytochrome oxidase bimolecular complex.

    OpenAIRE

    Edwards, A M; Blasie, J. K.; Bean, J. C.

    1998-01-01

    Vectorially oriented monolayers of yeast cytochrome c and its bimolecular complex with bovine heart cytochrome c oxidase have been formed by self-assembly from solution. Both quartz and Ge/Si multilayer substrates were chemical vapor deposited with an amine-terminated alkylsiloxane monolayer that was then reacted with a hetero-bifunctional cross-linking reagent, and the resulting maleimide endgroup surface then provided for covalent interactions with the naturally occurring single surface cys...

  10. Purification of the Cytochrome c Reductase/Cytochrome c Oxidase Super Complex of Yeast Mitochondria

    OpenAIRE

    Braun, Hans-Peter; Sunderhaus, Stephanie; Boekema, Egbert J.; Kouřil, Roman

    2009-01-01

    The protein complexes of the respiratory chain interact by forming large protein particles called respiratory supercomplexes or ‘‘respirasomes’’. Biochemical characterization of these particles proved to be difficult because of their instability. Here we describe a strategy to isolate and characterize the cytochrome c reductase/cytochrome c oxidase supercomplex of yeast, also termed the III + IV supercomplex, which is based on lactate cultivation of yeast, gentle isolation of mitochondria, me...

  11. Cytochrome c1 exhibits two binding sites for cytochrome c in plants

    OpenAIRE

    Moreno-Beltrán, Blas; Díaz-Quintana, Antonio; González-Arzola, Katiuska; Velázquez-Campoy, Adrián; Rosa, MIguel A. de la; Díaz-Moreno, Irene

    2014-01-01

    In plants, channeling of cytochrome c molecules between complexes III and IV has been purported to shuttle electrons within the supercomplexes instead of carrying electrons by random diffusion across the intermembrane bulk phase. However, the mode plant cytochrome c behaves inside a supercomplex such as the respirasome, formed by complexes I, III and IV, remains obscure from a structural point of view. Here, we report ab-initio Brownian dynamics calculations and nuclear magnetic resonance-dri...

  12. Complex structure of cytochrome c-cytochrome c oxidase reveals a novel protein-protein interaction mode.

    Science.gov (United States)

    Shimada, Satoru; Shinzawa-Itoh, Kyoko; Baba, Junpei; Aoe, Shimpei; Shimada, Atsuhiro; Yamashita, Eiki; Kang, Jiyoung; Tateno, Masaru; Yoshikawa, Shinya; Tsukihara, Tomitake

    2017-02-01

    Mitochondrial cytochrome c oxidase (CcO) transfers electrons from cytochrome c (Cyt.c) to O2 to generate H2O, a process coupled to proton pumping. To elucidate the mechanism of electron transfer, we determined the structure of the mammalian Cyt.c-CcO complex at 2.0-Å resolution and identified an electron transfer pathway from Cyt.c to CcO. The specific interaction between Cyt.c and CcO is stabilized by a few electrostatic interactions between side chains within a small contact surface area. Between the two proteins are three water layers with a long inter-molecular span, one of which lies between the other two layers without significant direct interaction with either protein. Cyt.c undergoes large structural fluctuations, using the interacting regions with CcO as a fulcrum. These features of the protein-protein interaction at the docking interface represent the first known example of a new class of protein-protein interaction, which we term "soft and specific". This interaction is likely to contribute to the rapid association/dissociation of the Cyt.c-CcO complex, which facilitates the sequential supply of four electrons for the O2 reduction reaction.

  13. Discovery of a magnetic field in the early B-type star σ Lupi

    Science.gov (United States)

    Henrichs, H. F.; Kolenberg, K.; Plaggenborg, B.; Marsden, S. C.; Waite, I. A.; Landstreet, J. D.; Wade, G. A.; Grunhut, J. H.; Oksala, M. E.

    2012-09-01

    Context. Magnetic early B-type stars are rare. Indirect indicators are needed to identify them before investing in time-intensive spectropolarimetric observations. Aims: We use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of ultraviolet (UV) stellar wind lines occurring symmetric about the approximate rest wavelength. Our aim is to identify probable magnetic candidates which would become targets for follow-up spectropolarimetry to search for a magnetic field. Methods: From the UV wind line variability the B1/B2V star σ Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the least-squares deconvolution method. Results: The UV line variations of σ Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100 G with error bars of typically 20 G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical-line variations are consistent with the photometric period of 3.02 d, which we identify with the rotation period of the star. Additional observations with ESPaDOnS attached to the CFHT confirmed this discovery, and allowed the determination of a precise magnetic period. Analysis revealed that σ Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a chemically spotted surface. Conclusions.σ Lupi is a magnetic oblique rotator, and is a He-strong star. Like in other magnetic B stars the UV wind emission appears to originate close to the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.01972 ± 0.00043 d magnetic rotation period is consistent with

  14. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Jian-Ching; Rebrin, Igor [Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (United States); Klichko, Vladimir; Orr, William C. [Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275 (United States); Sohal, Rajindar S., E-mail: sohal@usc.edu [Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90033 (United States)

    2010-10-08

    Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  15. Cardiac effects of 3 months treatment of acromegaly evaluated by magnetic resonance imaging and B-type natriuretic peptides

    DEFF Research Database (Denmark)

    Andreassen, Mikkel; Faber, Jens; Kjær, Andreas;

    2010-01-01

    of acromegaly is initiated. This was a three months prospective study investigating short-term cardiac effects of treatment in acromegalic patients. Cardiac function was evaluated by the gold standard method cardiac magnetic resonance imaging (CMRI) and circulating levels of B-type natriuretic peptides (BNP......Long-term treatment of acromegaly prevents aggravation and reverses associated heart disease. A previous study has shown a temporary increase in serum levels of the N-terminal fraction of pro B-type natriuretic peptide (NT-proBNP) suggesting an initial decline in cardiac function when treatment...... and NT-proBNP). CMRI was performed at baseline and after 3 months of treatment. Levels of IGF-I, BNP and NT-proBNP were measured after 0, 1, 2 and 3 months. Eight patients (5 males and 3 females, mean age 53 ± 12 years (range 30-70)) and 8 matched healthy control subjects were included. Median IGF-I Z...

  16. Cytochromes P450 of insects: the tip of the iceberg.

    Science.gov (United States)

    Scott, J G; Wen, Z

    2001-10-01

    The cytochrome P450-dependent monooxygenases are an extremely important metabolic system involved in the metabolism of endogenous compounds and xenobiotics. Collectively, P450 monooxygenases can metabolize numerous substrates and carry out multiple oxidative reactions. The large number of substrates metabolized is due to the plethora of P450 isoforms and to the broad substrate specificity of some isoforms. Monooxygenases of insects have several functional roles, including growth, development, feeding and protection against xenobiotics, including resistance to pesticides and tolerance to plant toxins. This review begins with background information about P450s and their evolution, followed by a discussion of the extraordinary diversity of insect P450s. Given the enormous interest in studying individual P450s, we then provide a synopsis of the different methods that have been used in their isolation and the substrates that are known to be metabolized. We conclude by summarizing the lessons we have learned from the study of individual insect P450s, including their roles in insecticide resistance, plant-insect interactions and insect physiology. However, these studies are just the 'tip of the iceberg'. Our knowledge continues to expand at a rapid pace, suggesting that the next decade will outpace the last in terms of improving our understanding of the cytochromes P450 of insects.

  17. Mutations induced by dacarbazine activated with cytochrome P-450.

    Science.gov (United States)

    Mudipalli, A; Nadadur, S S; Maccubbin, A E; Gurtoo, H L

    1995-03-01

    The mutagenicity of the antitumor drug dacarbazine (DTIC) is due to alkylation of cellular DNA by metabolites resulting from the metabolism of this drug by the mixed function oxidase system. In the present study, we used an in vitro shuttle vector assay to study the base and sequence specificity of mutagenesis by DTIC. The shuttle vector plasmid pSP189 was treated with DTIC (1-2.5 mM) in vitro in a reconstituted cytochrome P-450 system at 37 degrees C for either 30 or 60 min. SupF tRNA gene insert contained in the plasmid was sequenced after replication of the drug-treated plasmid in human Ad 293 cells followed by amplification in indicator bacteria. Mutagenesis of DTIC in this system was dependent upon the presence of the cytochrome P-450 reconstituted system and NADPH. Mutations induced by DTIC included single base substitutions (35%), single base deletions (30.5%), single base insertions (19.4%) and large deletions (13.8%). Among the substitutions, transversions and transitions were in the ratio of 1:0.7. Base pairs 108 and 127 in the SupF tRNA of the pSP189 were identified as mutational hot spots.

  18. Invasive and noninvasive correlations of B-type natriuretic peptide in patients with heart failure due to Chagas cardiomyopathy.

    Science.gov (United States)

    Vilas-Boas, Fábio; Feitosa, Gilson Soares; Soares, Milena B P; Pinho-Filho, Joel Alves; Nascimento, Thais; Barojas, Marcos M; Andrade, Marcus V S; Ribeiro-Dos-Santos, Ricardo; Bocchi, Edimar

    2008-01-01

    Heart failure due to Chagas cardiomyopathy (HFCC) differs from failure with other etiologies because of the occurrence of intense inflammatory infiltrate and right ventricle compromise. This article investigates correlations of B-type natriuretic peptide (BNP) levels with parameters of severity in HFCC. Twenty-eight patients and 8 normal controls underwent heart catheterization and clinical and laboratory analyses. BNP levels were higher in patients with HFCC (PHFCC, irrespective of NYHA class, and that the occurrence of HFCC correlates with severity of disease.

  19. THE O- AND B-TYPE STELLAR POPULATION IN W3: BEYOND THE HIGH-DENSITY LAYER

    Energy Technology Data Exchange (ETDEWEB)

    Kiminki, Megan M.; Kim, Jinyoung Serena; Bagley, Micaela B.; Rieke, George H. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Sherry, William H., E-mail: mbagley@email.arizona.edu [National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

    2015-11-01

    We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an R{sub V} of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H ii region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8–10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially variable nebular emission.

  20. The O- and B-Type Stellar Population in W3: Beyond the High-Density Layer

    CERN Document Server

    Kiminki, Megan M; Bagley, Micaela B; Sherry, William H; Rieke, George H

    2015-01-01

    We present the first results from our survey of the star-forming complex W3, combining VRI photometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically-confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an Rv of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 HII region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8--10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtr...

  1. Functional and structural evaluation of bovine heart cytochrome c oxidase incorporated into bicelles.

    Science.gov (United States)

    Musatov, Andrey; Siposova, Katarina; Kubovcikova, Martina; Lysakova, Veronika; Varhac, Rastislav

    2016-02-01

    Bilayered long- and short-chain phospholipid assemblies, known as bicelles, have been widely used as model membranes in biological studies. However, to date, there has been no demonstration of structural or functional viability for the fundamental mitochondrial electron transport complexes reconstituted into or interacting with bicelles. In the present work, bicelles were formed from the mixture of long- and short-chain phospholipids, specifically 14:0 and 6:0 phosphatidylcholines (1,2-dimyristoyl-sn-glycero-3-phosphocholine, (DMPC) and 1,2-dihexanoyl-sn-glycero-3-phosphocholine, (DHPC)). Isolated from bovine heart, cytochrome c oxidase was successfully incorporated into bicelles. Bicelles and cytochrome c oxidase incorporated into bicelles ("proteobicelles") were characterized by absorption spectroscopy, dynamic light scattering, atomic force microscopy, sedimentation velocity and differential scanning calorimetry. It was demonstrated that at total concentration of phospholipids CL = 24 mM and the molar ratio (q) of long-chain DMPC over short-chain DHPC equal to 0.4, the diameter of bicelles formed at neutral pH is in the range of 30-60 nm with the thickness of bicelles of about 4 nm. Adding cytochrome c oxidase to bicelles unified the size of the resulting proteobicelles to about 160 nm. Cytochrome c oxidase in bicelles was fully reducible by artificial donors of electrons, exhibited "normal" reaction with external ligands, and was fully active. Both, sedimentation velocity analysis and temperature-induced denaturation indicated that enzyme in bicelles is monomeric. We concluded that cytochrome c oxidase in bicelles maintains its structural and functional integrity, and that bicelles can be used for more comprehensive investigation of cytochrome c oxidase and most likely other mitochondrial electron transfer complexes.

  2. Functional implications of pigments bound to a cyanobacterial cytochrome b6f complex.

    Science.gov (United States)

    Wenk, Stephan-Olav; Schneider, Dirk; Boronowsky, Ute; Jäger, Cornelia; Klughammer, Christof; de Weerd, Frank L; van Roon, Henny; Vermaas, Wim F J; Dekker, Jan P; Rögner, Matthias

    2005-01-01

    A highly purified cytochrome b(6)f complex from the cyanobacterium Synechocystis sp. PCC 6803 selectively binds one chlorophyll a and one carotenoid in analogy to the recent published structure from two other b(6)f complexes. The unknown function of these pigments was elucidated by spectroscopy and site-directed mutagenesis. Low-temperature redox difference spectroscopy showed red shifts in the chlorophyll and carotenoid spectra upon reduction of cytochrome b(6), which indicates coupling of these pigments with the heme groups and thereby with the electron transport. This is supported by the correlated kinetics of these redox reactions and also by the distinct orientation of the chlorophyll molecule with respect to the heme cofactors as shown by linear dichroism spectroscopy. The specific role of the carotenoid echinenone for the cytochrome b(6)f complex of Synechocystis 6803 was elucidated by a mutant lacking the last step of echinenone biosynthesis. The isolated mutant complex preferentially contained a carotenoid with 0, 1 or 2 hydroxyl groups (most likely 9-cis isomers of beta-carotene, a monohydroxy carotenoid and zeaxanthin, respectively) instead. This indicates a substantial role of the carotenoid - possibly for strucure and assembly - and a specificity of its binding site which is different from those in most other oxygenic photosynthetic organisms. In summary, both pigments are probably involved in the structure, but may also contribute to the dynamics of the cytochrome b(6)f complex.

  3. Electrostatic effect on electron transfer between cytochrome b5 and cytochrome c

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The binding and electron transfer between wild type, E44A, E56A, E44/56A, E44/48/56A/D60Aand F35Y variants of cytochrome b5 and cytochrome c were studied. When mixed with cytochrome c, the cytochrome b5E44/48/56A/D60A did not show the typical UV-vis difference spectrum of absorption, indicating that the alteration ofthe surface electrostatic potential obviously influenced the spectrum. The electron transfer rates of wild type cytochromeb5, its variants and cytochrome e at different temperature and ionic strength exhibited an order of F35Y > wild type >E56A > E44A > E44/48/56A/D60A. The enthalpy and entropy of the reaction did not change obviously, suggestingthat the mutation did not significantly disturb the electron transfer conformation. The investigation of electron transfer rateconstants at different ionic strength demonstrated that electrostatic interaction obviously affected the electron transfer pro-cess. The significant difference of Cyt b5 F35Y and E44/48/56A/D60A from the wild type protein further confirmed thegreat importance of the electrostatic interaction in the protein electron transfer.

  4. The redox state of cytochrome c modulates resistance to methotrexate in human MCF7 breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Susana Barros

    Full Text Available BACKGROUND: Methotrexate is a chemotherapeutic agent used to treat a variety of cancers. However, the occurrence of resistance limits its effectiveness. Cytochrome c in its reduced state is less capable of triggering the apoptotic cascade. Thus, we set up to study the relationship among redox state of cytochrome c, apoptosis and the development of resistance to methotrexate in MCF7 human breast cancer cells. RESULTS: Cell incubation with cytochrome c-reducing agents, such as tetramethylphenylenediamine, ascorbate or reduced glutathione, decreased the mortality and apoptosis triggered by methotrexate. Conversely, depletion of glutathione increased the apoptotic action of methotrexate, showing an involvement of cytochrome c redox state in methotrexate-induced apoptosis. Methotrexate-resistant MCF7 cells showed increased levels of endogenous reduced glutathione and a higher capability to reduce exogenous cytochrome c. Using functional genomics we detected the overexpression of GSTM1 and GSTM4 in methotrexate-resistant MCF7 breast cancer cells, and determined that methotrexate was susceptible of glutathionylation by GSTs. The inhibition of these GSTM isoforms caused an increase in methotrexate cytotoxicity in sensitive and resistant cells. CONCLUSIONS: We conclude that overexpression of specific GSTMs, GSTM1 and GSTM4, together with increased endogenous reduced glutathione levels help to maintain a more reduced state of cytochrome c which, in turn, would decrease apoptosis, thus contributing to methotrexate resistance in human MCF7 breast cancer cells.

  5. The cytochrome b5 reductase HPO-19 is required for biosynthesis of polyunsaturated fatty acids in Caenorhabditis elegans.

    Science.gov (United States)

    Zhang, Yuru; Wang, Haizhen; Zhang, Jingjing; Hu, Ying; Zhang, Linqiang; Wu, Xiaoyun; Su, Xiong; Li, Tingting; Zou, Xiaoju; Liang, Bin

    2016-04-01

    Polyunsaturated fatty acids (PUFAs) are fatty acids with backbones containing more than one double bond, which are introduced by a series of desaturases that insert double bonds at specific carbon atoms in the fatty acid chain. It has been established that desaturases need flavoprotein-NADH-dependent cytochrome b5 reductase (simplified as cytochrome b5 reductase) and cytochrome b5 to pass through electrons for activation. However, it has remained unclear how this multi-enzyme system works for distinct desaturases. The model organism Caenorhabditis elegans contains seven desaturases (FAT-1, -2, -3, -4, -5, -6, -7) for the biosynthesis of PUFAS, providing an excellent model in which to characterize different desaturation reactions. Here, we show that RNAi inactivation of predicted cytochrome b5 reductases hpo-19 and T05H4.4 led to increased levels of C18:1n-9 but decreased levels of PUFAs, small lipid droplets, decreased fat accumulation, reduced brood size and impaired development. Dietary supplementation with different fatty acids showed that HPO-19 and T05H4.4 likely affect the activity of FAT-1, FAT-2, FAT-3, and FAT-4 desaturases, suggesting that these four desaturases use the same cytochrome b5 reductase to function. Collectively, these findings indicate that cytochrome b5 reductase HPO-19/T05H4.4 is required for desaturation to biosynthesize PUFAs in C. elegans.

  6. The ccoNOQP gene cluster codes for a cb-type cytochrome oxidase that functions in aerobic respiration of Rhodobacter capsulatus.

    Science.gov (United States)

    Thöny-Meyer, L; Beck, C; Preisig, O; Hennecke, H

    1994-11-01

    The genes for a new type of a haem-copper cytochrome oxidase were cloned from Rhodobacter capsulatus strain 37b4, using the Bradyrhizobium japonicum fixNOQP gene region as a hybridizing probe. Four genes, probably organized in an operon (ccoNOQP), were identified; their products share extensive amino acid sequence similarity with the FixN, O, Q and P proteins that have recently been shown to be the subunits of a cb-type oxidase. CcoN is a b-type cytochrome, CcoO and CcoP are membrane-bound mono- and dihaem c-type cytochromes and CcoQ is a small membrane protein of unknown function. Genes for a similar oxidase are also present in other non-rhizobial bacterial species such as Azotobacter vinelandii, Agrobacterium tumefaciens and Pseudomonas aeruginosa, as revealed by polymerase chain reaction analysis. A ccoN mutant was constructed whose phenotype, in combination with the structural information on the gene products, provides evidence that the CcoNOQP oxidase is a cytochrome c oxidase of the cb type, which supports aerobic respiration in R. capsulatus and which is probably identical to the cbb3-type oxidase that was recently purified from a different strain of the same species. Mutant analysis also showed that this oxidase has no influence on photosynthetic growth and nitrogen-fixation activity.

  7. Molecular characterization of pyraclostrobin resistance and structural diversity of the cytochrome b gene in Botrytis cinerea from apple.

    Science.gov (United States)

    Yin, Y N; Kim, Y K; Xiao, C L

    2012-03-01

    Botrytis cinerea isolates obtained from apple orchards were screened for resistance to the quinone outside inhibitor (QoI) pyraclostrobin. Of the 220 isolates tested, 43 (19.5%) were resistant to pyraclostrobin. Analysis of partial sequences of the cytochrome b gene (cyt b) in five pyraclostrobin-resistant (PR) and five pyraclostrobin-sensitive (PS) isolates showed that PR isolates harbored the point mutation leading to the substitution of glycine by alanine at codon position 143 in cyt b (G143A). Two pairs of allele-specific primers were designed based on this point mutation, and allele-specific polymerase chain reaction analysis with these primers showed that all 73 PR isolates (including 30 collected from decayed apple fruit) harbored the G143A mutation but PS isolates did not. Six pairs of primers were designed to analyze the presence of various introns in cyt b. There were six types (I to VI) of cyt b present in 247 isolates of B. cinerea collected from various apple-production areas in Washington State. Of the 247 isolates, 23 had type I cyt b containing all four introns (Bcbi-67/68, Bcbi-131/132, Bcbi-143/144, and Bcbi-164), 176 had type II cyt b containing three introns (Bcbi-67/68, Bcbi-131/132, and Bcbi-164), six had type III cyt b containing two introns (Bcbi-67/68 and Bcbi-131/132), one had type IV cyt b containing two introns (Bcbi-131/132 and Bcbi-164), one had type V cyt b containing only the Bcbi-131/132 intron, and 40 had type VI cyt b containing no introns. This is the first report of types III to VI cyt b present in B. cinerea. All 73 PR isolates did not carry the Bcbi-143/144 intron in cyt b. Of the 247 isolates tested, >90% did not carry the Bcbi-143/144 intron in cyt b, suggesting that B. cinerea populations from apple pose a high inherent risk for the development of resistance to QoIs because the presence of this intron in cyt b prevents the occurrence of G143A-mediated resistance. Analysis of genetic background based on three microsatellite

  8. Engineering cytochrome p450 enzymes.

    Science.gov (United States)

    Gillam, Elizabeth M J

    2008-01-01

    The last 20 years have seen the widespread and routine application of methods in molecular biology such as molecular cloning, recombinant protein expression, and the polymerase chain reaction. This has had implications not only for the study of toxicological mechanisms but also for the exploitation of enzymes involved in xenobiotic clearance. The engineering of P450s has been performed with several purposes. The first and most fundamental has been to enable successful recombinant expression in host systems such as bacteria. This in turn has led to efforts to solubilize the proteins as a prerequisite to crystallization and structure determination. Lagging behind has been the engineering of enzyme activity, hampered in part by our still-meager comprehension of fundamental structure-function relationships in P450s. However, the emerging technique of directed evolution holds promise in delivering both engineered enzymes for use in biocatalysis and incidental improvements in our understanding of sequence-structure and sequence-function relationships, provided that data mining can extract the fundamental correlations underpinning the data. From the very first studies on recombinant P450s, efforts were directed toward constructing fusions between P450s and redox partners in the hope of generating more efficient enzymes. While this aim has been allowed to lie fallow for some time, this area merits further investigation as does the development of surface-displayed P450 systems for biocatalytic and biosensor applications. The final application of engineered P450s will require other aspects of their biology to be addressed, such as tolerance to heat, solvents, and high substrate and product concentrations. The most important application of these enzymes in toxicology in the near future is likely to be the biocatalytic generation of drug metabolites for the pharmaceutical industry. Further tailoring will be necessary for specific toxicological applications, such as in

  9. Molecular basis of infantile reversible cytochrome c oxidase deficiency myopathy.

    Science.gov (United States)

    Horvath, Rita; Kemp, John P; Tuppen, Helen A L; Hudson, Gavin; Oldfors, Anders; Marie, Suely K N; Moslemi, Ali-Reza; Servidei, Serenella; Holme, Elisabeth; Shanske, Sara; Kollberg, Gittan; Jayakar, Parul; Pyle, Angela; Marks, Harold M; Holinski-Feder, Elke; Scavina, Mena; Walter, Maggie C; Coku, Jorida; Günther-Scholz, Andrea; Smith, Paul M; McFarland, Robert; Chrzanowska-Lightowlers, Zofia M A; Lightowlers, Robert N; Hirano, Michio; Lochmüller, Hanns; Taylor, Robert W; Chinnery, Patrick F; Tulinius, Mar; DiMauro, Salvatore

    2009-11-01

    Childhood-onset mitochondrial encephalomyopathies are usually severe, relentlessly progressive conditions that have a fatal outcome. However, a puzzling infantile disorder, long known as 'benign cytochrome c oxidase deficiency myopathy' is an exception because it shows spontaneous recovery if infants survive the first months of life. Current investigations cannot distinguish those with a good prognosis from those with terminal disease, making it very difficult to decide when to continue intensive supportive care. Here we define the principal molecular basis of the disorder by identifying a maternally inherited, homoplasmic m.14674T>C mt-tRNA(Glu) mutation in 17 patients from 12 families. Our results provide functional evidence for the pathogenicity of the mutation and show that tissue-specific mechanisms downstream of tRNA(Glu) may explain the spontaneous recovery. This study provides the rationale for a simple genetic test to identify infants with mitochondrial myopathy and good prognosis.

  10. Impacts of diversification of cytochrome P450 on plant metabolism.

    Science.gov (United States)

    Mizutani, Masaharu

    2012-01-01

    Cytochrome P450 monooxygenases (P450s) catalyze a wide variety of monooxygenation reactions in primary and secondary metabolism in plants. The share of P450 genes in each plant genome is estimated to be up to 1%. This implies that the diversification of P450 has made a significant contribution to the ability to acquire the emergence of new metabolic pathways during land plant evolution. The P450 families conserved universally in land plants contribute to their chemical defense mechanisms. Several P450s are involved in the biosynthesis and catabolism of plant hormones. Species-specific P450 families are essential for the biosynthetic pathways of phytochemicals such as terpenoids and alkaloids. Genome wide analysis of the gene clusters including P450 genes will provide a clue to defining the metabolic roles of orphan P450s. Metabolic engineering with plant P450s is an important technology for large-scale production of valuable phytochemicals such as medicines.

  11. [Cytochrome P450 activity and its alteration in different diseases].

    Science.gov (United States)

    Orellana, Myriam; Guajardo, Viviana

    2004-01-01

    Cytochrome P450 (CYP) enzymes participate in the metabolism of a variety of naturally occurring and foreign compounds by reactions requiring NADPH and O2. The diversity of reactions catalyzed and its extensive substrate specificity render CYP enzymes as one of the most versatile known catalysts. Individual members of the CYP superfamily are expressed in almost every cell type in the body. As compared to hepatic enzymes, the regulation of human extrahepatic CYPs has not been so well studied. In general, the levels of some hepatic CYP enzymes are depressed by diseases, causing potential and documented impairment of drug clearence and clinical drug toxicity. However, modulation of CYPs is enzyme selective and this selectivity differs in different diseases. This article reviews some basic concepts about CYP and its regulation in some disease states such as hypertension, diabetes, obesity and hepatic, infectious and inflammatory diseases.

  12. Cytochrome P450 as dimerization catalyst in diketopiperazine alkaloid biosynthesis.

    Science.gov (United States)

    Saruwatari, Takayoshi; Yagishita, Fumitoshi; Mino, Takashi; Noguchi, Hiroshi; Hotta, Kinya; Watanabe, Kenji

    2014-03-21

    As dimeric natural products frequently exhibit useful biological activities, identifying and understanding their mechanisms of dimerization is of great interest. One such compound is (−)-ditryptophenaline, isolated from Aspergillus flavus, which inhibits substance P receptor for potential analgesic and anti-inflammatory activity. Through targeted gene knockout in A. flavus and heterologous yeast gene expression, we determined for the first time the gene cluster and pathway for the biosynthesis of a dimeric diketopiperazine alkaloid. We also determined that a single cytochrome P450, DtpC, is responsible not only for pyrroloindole ring formation but also for concurrent dimerization of N-methylphenylalanyltryptophanyl diketopiperazine monomers into a homodimeric product. Furthermore, DtpC exhibits relaxed substrate specificity, allowing the formation of two new dimeric compounds from a non-native monomeric precursor, brevianamide F. A radical-mediated mechanism of dimerization is proposed.

  13. The reaction of neuroglobin with potential redox protein partners cytochrome b5  and cytochrome c

    DEFF Research Database (Denmark)

    Fago, Angela; Mathews, A.J.; Moens, L.

    2006-01-01

    Previously identified, potentially neuroprotective reactions of neuroglobin require the existence of yet unknown redox partners. We show here that the reduction of ferric neuroglobin by cytochrome b5 is relatively slow (k=6×102M-1s-1 at pH 7.0) and thus is unlikely to be of physiological...... significance. In contrast, the reaction between ferrous neuroglobin and ferric cytochrome c is very rapid (k=2×107M-1s-1) with an apparent overall equilibrium constant of 1μM. Based on this data we propose that ferrous neuroglobin may well play a role in preventing apoptosis...

  14. Kink degeneracy and rogue potential solution for the (3+1)-dimensional B-type Kadomtsev--Petviashvili equation

    Indian Academy of Sciences (India)

    ZHENHUI XU; HANLIN CHEN; ZHENGDE DAI

    2016-08-01

    In this paper, we obtained the exact breather-type kink soliton and breather-type periodic soliton solutions for the (3+1)-dimensional B-type Kadomtsev--Petviashvili (BKP) equation using the extended homoclinic test technique. Some new nonlinear phenomena, such as kink and periodic degeneracies, are investigated. Using the homoclinic breather limit method, some new rational breather solutions are found as well. Meanwhile, we also obtained the rational potential solution which is found to be just a rogue wave. These results enrich thevariety of the dynamics of higher-dimensional nonlinear wave field.

  15. Studies on NADH(NADPH)-cytochrome c reductase (FMN-containing) from yeast: steady-state kinetic properties of the flavoenzyme from top-fermenting ale yeast.

    Science.gov (United States)

    Johnson, M S; Kuby, S A

    1986-02-15

    A study of the steady-state kinetics of NADH(NADPH)-cytochrome c reductase (FMN-containing) from ale yeast (M. S. Johnson and S. A. Kuby (1985) J. Biol. Chem. 260, 12341-12350) has led to a postulated three-substrate random-ordered hybrid mechanism, where NAD(P)H and FMN add randomly and very likely in a steady-state fashion, followed by an ordered addition of cytochrome c. Kinetic parameters have been derived from this mechanism. Arrhenius plots showed large differences between NADH and NADPH, as the substrate-reductant. Menadione accelerated cytochrome c reduction and also O2 uptake, but vitamin K1 and coenzyme Q10 were ineffective as electron mediators, possibly as a result of their insolubility. With NADPH as the substrate-reductant, the order of the rate of reduction of electron acceptors was ferricyanide greater than DCIP greater than cytochrome c greater than oxygen; with menadione, the specificity sequence was cytochrome c greater than ferricyanide greater than DCIP greater than oxygen. With NADH, the order was ferricyanide greater than cytochrome c greater than oxygen greater than DCIP, which changed to cytochrome c greater than ferricyanide greater than oxygen greater than DCIP on addition of menadione. Cytochrome b5 was also reduced in the absence of oxygen. No transhydrogenase activity was observed, but the reduced thionicotinamide analogs of NADH and NADPH acted as substrates. Superoxide dismutase inhibited cytochrome c reduction in air by 50%, but O2-. was not necessary for cytochrome c reduction, as evidenced by the increase in rate in the absence of O2. The product of the reaction with oxygen appeared to be H2O2.

  16. The nature of CuA in cytochrome c oxidase

    OpenAIRE

    Stevens, Tom H.; Martin, Craig T.; Wang, Hsin; Brudvig, Gary W.; Scholes, Charles P.; Chan, Sunney I.

    1982-01-01

    The isolation and purification of yeast cytochrome c oxidase is described. Characterization of the purified protein indicates that it is spectroscopically identical with cytochrome c oxidase isolated from beef heart. Preparations of isotopically substituted yeast cytochrome c oxidase are obtained incorporating [1,3-15N2]histidine or [beta,beta- 2H2]cysteine. Electron paramagnetic resonance and electron nuclear double resonance spectra of the isotopically substituted proteins identify unambigu...

  17. Engineering human cytochrome P450 enzymes into catalytically self-sufficient chimeras using molecular Lego.

    Science.gov (United States)

    Dodhia, Vikash Rajnikant; Fantuzzi, Andrea; Gilardi, Gianfranco

    2006-10-01

    The membrane-bound human cytochrome P450s have essential roles in the metabolism of endogenous compounds and drugs. Presented here are the results on the construction and characterization of three fusion proteins containing the N-terminally modified human cytochrome P450s CYP2C9, CY2C19 and CYP3A4 fused to the soluble NADPH-dependent oxidoreductase domain of CYP102A1 from Bacillus megaterium. The constructs, CYP2C9/BMR, CYP2C19/BMR and CYP3A4/BMR are well expressed in Escherichia coli as holo proteins. The chimeras can be purified in the absence of detergent and the purified enzymes are both active and correctly folded in the absence of detergent, as demonstrated by circular dichroism and functional studies. Additionally, in comparison with the parent P450 enzyme, these chimeras have greatly improved solubility properties. The chimeras are catalytically self-sufficient and present turnover rates similar to those reported for the native enzymes in reconstituted systems, unlike previously reported mammalian cytochrome P450 fusion proteins. Furthermore the specific activities of these chimeras are not dependent on the enzyme concentration present in the reaction buffer and they do not require the addition of accessory proteins, detergents or phospholipids to be fully active. The solubility, catalytic self-sufficiency and wild-type like activities of these chimeras would greatly simplify the studies of cytochrome P450 mediated drug metabolism in solution.

  18. Comparative kinetics of Qi site inhibitors of cytochrome bc1 complex: picomolar antimycin and micromolar cyazofamid.

    Science.gov (United States)

    Li, Hui; Zhu, Xiao-Lei; Yang, Wen-Chao; Yang, Guang-Fu

    2014-01-01

    Antimycin and cyazofamid are specific inhibitors of the mitochondrial respiratory chain and bind to the Qi site of the cytochrome bc1 complex. With the aim to understand the detailed molecular inhibition mechanism of Qi inhibitors, we performed a comparative investigation of the inhibitory kinetics of them against the porcine bc1 complex. The results showed that antimycin is a slow tight-binding inhibitor of succinate-cytochrome c reductase (SCR) with Ki  = 0.033 ± 0.00027 nm and non-competitive inhibition with respect to cytochrome c. Cyazofamid is a classical inhibitor of SCR with Ki  = 12.90 ± 0.91 μm and a non-competitive inhibitor with respect to cytochrome c. Both of them show competitive inhibition with respect to substrate DBH2 . Further molecular docking and quantum mechanics calculations were performed. The results showed that antimycin underwent significant conformational change upon the binding. The energy barrier between the conformations in the crystal and in the binding pocket is ~13.63 kcal/mol. Antimycin formed an H-bond with Asp228 and two water-bridged H-bonds with Lys227 and His201, whereas cyazofamid formed only one H-bond with Asp228. The conformational change and the different hydrogen bonding network might account for why antimycin is a slow tight-binding inhibitor, whereas cyazofamid is a classic inhibitor.

  19. Respiratory cytochrome c oxidase can be efficiently reduced by the photosynthetic redox proteins cytochrome c6 and plastocyanin in cyanobacteria.

    Science.gov (United States)

    Navarro, José A; Durán, Raúl V; De la Rosa, Miguel A; Hervás, Manuel

    2005-07-04

    Plastocyanin and cytochrome c6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. Although their role as electron shuttle between the cytochrome b6f and photosystem I complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. Here, we present the first time-resolved analysis showing that both cytochrome c6 and plastocyanin can be efficiently oxidized by the aa3 type cytochrome c oxidase in Nostoc sp. PCC 7119. The apparent electron transfer rate constants are ca. 250 and 300 s(-1) for cytochrome c6 and plastocyanin, respectively. These constants are 10 times higher than those obtained for the oxidation of horse cytochrome c by the oxidase, in spite of being a reaction thermodynamically more favourable.

  20. Cytochrome P450s and cytochrome P450 reductase in the olfactory organ of the cotton leafworm Spodoptera littoralis.

    Science.gov (United States)

    Pottier, M-A; Bozzolan, F; Chertemps, T; Jacquin-Joly, E; Lalouette, L; Siaussat, D; Maïbèche-Coisne, M

    2012-12-01

    Cytochrome P450 enzymes (P450s) are involved in many physiological functions in insects, such as the metabolism of signal molecules, adaptation to host plants and insecticide resistance. Several P450s have been reported in the olfactory organs of insects, the antennae, and have been proposed to play a role in odorant processing and/or xenobiotic metabolism. Despite recent transcriptomic analyses in several species, the diversity of antennal P450s in insects has not yet been investigated. Here, we report the identification of 37 putative P450s expressed in the antennae of the pest moth Spodoptera littoralis, as well as the characterization of a redox partner, cytochrome P450 reductase (CPR). Phylogenetic analysis revealed that S. littoralis P450s belong to four clades defined by their conservation with vertebrate P450s and their cellular localization. Interestingly, the CYP3 and CYP4 clans, which have been described to be mainly involved in the metabolism of plant compounds and xenobiotics, were largely predominant. More surprisingly, two P450s related to ecdysteroid metabolism were also identified. Expression patterns in adult and larval tissues were studied. Eight P450s appeared to be specific to the chemosensory organs, ie the antennae and proboscis, suggesting a specific role in odorant and tastant processing. Moreover, exposure of males to a plant odorant down-regulated the transcript level of CPR, revealing for the first time the regulation of this gene by odorants within insect antennae. This work suggests that the antennae of insects are a key site for P450-mediated metabolism of a large range of exogenous and endogenous molecules.

  1. The VLT-FLAMES Tarantula Survey XVIII. Classifications and radial velocities of the B-type stars

    CERN Document Server

    Evans, C J; Dufton, P L; Howarth, I D; Walborn, N R; Markova, N; Clark, J S; de Mink, S E; de Koter, A; Dunstall, P R; Hénault-Brunet, V; Apellániz, J Maíz; McEvoy, C M; Sana, H; Simón-Díaz, S; Taylor, W D; Vink, J S

    2015-01-01

    We present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. We investigate the spatial distribution of the radial velocities across the 30 Dor region, and use the results to identify candidate runaway stars. Excluding potential runaways and members of two older clusters in the survey region (SL 639 and Hodge 301), we determine a systemic velocity for 30 Dor of 271.6 +/- 12.2 km/s from 273 presumed single stars. Employing a 3-sigma criterion we identify nine candidate runaway stars (2.9% of the single stars with radial-velocity estimates). The projected rotational velocities of the candidate runaways appear to be significantly different to those of the full B-type sample, with a strong preference for either large (>345 km/s) or...

  2. Effects of structural imperfection on gelatinization characteristics of amylopectin starches with A- and B-type crystallinity.

    Science.gov (United States)

    Genkina, Natalia K; Wikman, Jeanette; Bertoft, Eric; Yuryev, Vladimir P

    2007-07-01

    The aim of the present work was to investigate the effect of physical structures on the properties of starch granules. Starches with a high amylopectin content possessing A- and B-type crystallinity were chosen for the study. The gelatinization temperature decreased in the following order: maize (A) > potato (B) > wheat (A) > barley (A), which did not reflect a correlation with the type of crystallinity. Low values of gelatinization temperature were accompanied with high free surface energy of the crystallites. It is proposed that these data are caused by different types of imperfections in starch crystals. Annealing resulted in an enhancement of the gelatinization temperature and a decrease of the free surface energy of the crystallites for all starches reflecting a partial improvement of crystalline perfection. A limited acid hydrolysis (lintnerization) of the starches decreased the gelatinization temperature because of a partial disruption of the crystalline lamellae and an increase of the amount of defects on the edges of the crystallites. Annealing of the lintnerized starches improved the structure of maize and potato starch, giving them similar structural and physicochemical parameters, which was opposite the behavior of the annealed sample from wheat. The possible nature of removable and nonremovable defects inside the crystalline region of the starch granules is discussed. It is concluded that, besides the allomorphic A- and B-types of crystal packing, physical defects in the crystals possess a major impact on starch gelatinization.

  3. Block synthesis of A (type 2) and B (type 2) tetrasaccharides related to the human ABO blood group system.

    Science.gov (United States)

    Ryzhov, Ivan M; Korchagina, Elena Yu; Popova, Inna S; Tyrtysh, Tatiana V; Paramonov, Alexander S; Bovin, Nicolai V

    2016-07-22

    Herein we report the synthesis of 3-aminopropyl glycosides of A (type 2) and B (type 2) tetrasaccharides via [3 + 1] block scheme. Peracetylated trichloroacetimidates of A and B trisaccharides were used as glycosyl donors. The well-known low reactivity of 4-OH group of N-acetyl-d-glucosamine forced us to test four glucosamine derivatives (3-Bz-1,6-anhydro-GlcNAc and 3-trifluoroacetamidopropyl β-glycosides of 3-Ac-6-Bn-GlcNAc, 3-Ac-6-Bn-GlcN3, and 3-Ac-6-Bn-GlcNAc2) to select the best glycosyl acceptor for the synthesis of type 2 tetrasaccharides. The desired tetrasacchrides were not isolated, when 3-trifluoroacetamidopropyl glycosyde of 3-Ac-6-Bn-GlcNAcβ was glycosylated. Glycosylation of 3-Bz-1,6-anhydro-GlcNAc derivative resulted in α-glycoside as a major product. High stereospecificity was achieved only in the synthesis of B (type 2) tetrasaccharide, when 3-trifluoroacetamidopropyl 3-Ac-6-Bn-GlcNAc2β was applied as the glycosyl acceptor (β/α 5:1), whereas glycosylation with trichloroacetimidate of A trisaccharide was not stereospecific (β/α 1.3:1). Glycosylation of 3-trifluoroacetamidopropyl glycoside of 3-Ac-6-Bn-GlcN3β with trichloroacetimidates of A and B trisaccharides provided the same stereochemical yield (β/α 1.5:1).

  4. Early type stars at high galactic latitudes II. Four evolved B-type stars of unusual chemical composition

    CERN Document Server

    Ramspeck, M; Edelmann, H

    2001-01-01

    We present the result of differential spectral analyses of a further four apparently normal B-type stars. Abundance anomalies (e.g. He, C, N enrichment), slow rotation and/or high gravities suggest that the programme stars are evolved low-mass B-type stars. In order to trace their evolutionary status several scenarios are discussed. Post-AGB evolution can be ruled out. PG 0229+064 and PG 1400+389 could be horizontal branch (HB) stars, while HD 76431 and SB 939 have already evolved away from the extreme HB (EHB). The low helium abundance of HD 76431 is consistent with post-EHB evolution. The enrichment in helium, carbon and nitrogen of the remaining stars can be explained either by deep mixing of nuclearly processed material to the surface or by diffusion processes modified by magnetic fields and/or stellar winds. A kinematic study of their galactic orbits indicates that the stars belong to an old disk population.

  5. The role of cytochrome P450s in polycyclic aromatic hydrocarbon carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Polzer, R.J.

    1993-01-01

    Metabolic activation of polycyclic aromatic hydrocarbons (PAH) to carcinogenic diol epoxides has been determined to be a critical step in tumor initiation by PAH. The key enzyme(s) involved in the metabolic activation are members of the cytochrome P450 superfamily. Two distinct isoforms of cytochrome P450 have been determined to be induced upon treatment of cells in culture with benzo(a)pyrene (B(a)P) by use of Immobilized Artificial Membrane Column High Performance Liquid Chromatography, Western blotting, Northern blotting, and in vitro metabolism studies. Cytochrome P4501A is involved in the metabolism of PAH in the human hepatoma cell line, HepG2; the human mammary carcinoma cell line, MCF-7; and the mouse hepatoma cell line; Hepa-1; whereas cytochrome P450EF is involved in this metabolism in both secondary hamster and mouse embryo cell cultures. Induction of cytochrome P450s by B(a)P generally leads to an increased metabolism of tritiated B(a)P, DMBA, and DB(a,1)P to water-soluble metabolities and to the formation of PAH-DNA adducts, suggesting that induction by B(a)P alters the metabolism of PAH to metabolic activation. DMBA induction of cytochrome P450s leads to various changes in metabolism and PAH-DNA binding and these changes were both cell and PAH specific. These results suggest that DMBA can shift metabolism of certain PAH towards metabolic activation in some cells, while in other cells DMBA or one of its metabolities can compete with other PAH for metabolic activation. UDP-glucuronosyl-transferase and epoxide hydrase do not have significant roles in detoxifying proximate or ultimate carcinogenic PAH metabolites, however, sulfotransferase and glutathione-S-transferase do detoxify proximate and ultimate carcinogenic metabolities in the HepG2 cell line. Finally, attempts to inhibit B(a)P metabolism and DNA-binding in intact cells in culture through conjugation of inhibitory cytochrome P4501A1 antibodies to insulin or folic acid were examined.

  6. Structural and functional analysis of aa3-type and cbb3-type cytochrome c oxidases of Paracoccus denitrificans reveals significant differences in proton-pump design

    OpenAIRE

    de Gier, Jan-Willem L.; Schepper, Mike; Reijnders, Willem N.M.; Dyck, Stef J. van; Slotboom, Dirk Jan; Warne, Antony; Saraste, Matti; Krab, Klaas; Finel, Moshe; Stouthamer, Adriaan H.; Van Spanning, Rob J. M.; van der Oost, John

    1996-01-01

    In Paracoccus denitrificans the aa3-type cytochrome c oxidase and the bb3-type quinol oxidase have previously been characterized in detail, both biochemically and genetically. Here we report on the isolation of a genomic locus that harbours the gene cluster ccoNOQP, and demonstrate that it encodes an alternative cbb3-type cytochrome c oxidase. This oxidase has previously been shown to be specifically induced at low oxygen tensions, suggesting that its expression is controlled by an oxygen-sen...

  7. Cytochrome c as a peroxidase : tuning of heme reactivity

    NARCIS (Netherlands)

    Diederix, Rutger Ernest Michiel

    2003-01-01

    This thesis describes the peroxidase activity of the electron-transfer protein cytochrome c, and how it is controlled by the protein matrix. It is shown that unfolding cytochrome c has the effect to significantly enhance its peroxidase activity of (up to several thousand-fold). This can be achieved

  8. A- to B-Type Olivine Fabric Transitions Associated with Hydration, Dehydration and Shear Above the Farallon Flat Slab

    Science.gov (United States)

    Behr, W. M.; Smith, D.

    2014-12-01

    We investigate mantle rocks associated with hydration, dehydration and shear above the Farallon flat-slab at its contact with the base of North America. The rocks we focus on are ultramafic inclusions hosted within serpentinized ultramafic microbreccia diatremes of the Navajo Volcanic Field (New Mexico) that erupted to the surface at the waning stages of the Laramide orogeny. A large number of petrological and geochronological studies have pinpointed the origin of these rocks to the hydrated mantle wedge above the Farallon slab as well as tectonically eroded and entrained fragments of the plate interface. We combine petrological observations and EBSD measurements of olivine grainsize and LPO to examine the effects of hydration on olivine fabric development in different parts of the supra-subduction zone mantle. The rocks examined include weakly deformed to strongly foliated tectonites we interpret to represent partially hydrated fragments of the upper plate mantle; and mylonites and ultramylonites we interpret to represent deformed fragments of the plate interface. The rocks deformed at temperatures ranging from 500-900°C based on thermometry, and olivine compositions in some record heating just before incorporation in the diatreme mix. We observe the following: Tectonites exhibit A-type bulk olivine LPOs, but show transitions to B-type LPO in local, fine-grained, dynamically recrystallized regions associated with hydrous minerals. Mylonites and ultramylonites with stable chlorite and/or antigorite and recrystallized grainsizes of less than 10μm show strong B-type olivine LPOs. A single mylonite with recrystallized grainsizes of ~35μm shows evidence for prograde metamorphism and dehydration through the chlorite breakdown reaction at temperatures above ~770°C. It contains no hydrous minerals and shows a strong A-type olivine LPO. Together these rocks demonstrate a strong correlation between hydration under high stress conditions, and B-type olivine LPO

  9. Predictive Values of N-Terminal Pro-B-Type Natriuretic Peptide and Cardiac Troponin I for Myocardial Fibrosis in Hypertrophic Obstructive Cardiomyopathy.

    Directory of Open Access Journals (Sweden)

    Changlin Zhang

    Full Text Available Both high-sensitivity cardiac troponin T and B-type natriuretic peptide are useful in detecting myocardial fibrosis, as determined by late gadolinium enhancement (LGE cardiovascular magnetic resonance (CMR, in patients with non-obstructive hypertrophic cardiomyopathy. However, their values to predict myocardial fibrosis in hypertrophic obstructive cardiomyopathy (HOCM remain unclear. We investigated the role of N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP and cardiac troponin I (cTnI to identify LGE-CMR in patients with HOCM.Peripheral concentrations of NT-proBNP and cTnI were determined in patients with HOCM (n = 163; age = 47.2 ± 10.8 years; 38.7% females. Contrast-enhanced CMR was performed to identify and quantify myocardial fibrosis.LGE was detected in 120 of 163 patients (73.6%. Patients with LGE had significantly higher levels of NT-proBNP and cTnI than those without LGE (1386.2 [904.6-2340.8] vs. 866.6 [707.2-1875.2] pmol/L, P = 0.003; 0.024 [0.010-0.049] vs. 0.010 [0.005-0.021] ng/ml, P <0.001, respectively. The extent of LGE was positively correlated with log cTnI (r = 0.371, P <0.001 and log NT-proBNP (r = 0.211, P = 0.007. On multivariable analysis, both log cTnI and maximum wall thickness (MWT were independent predictors of the presence of LGE (OR = 3.193, P = 0.033; OR = 1.410, P < 0.001, respectively, whereas log NT-proBNP was not. According to the ROC curve analysis, combined measurements of MWT ≥21 mm and/or cTnI ≥0.025 ng/ml indicated good diagnostic performance for the presence of LGE, with specificity of 95% or sensitivity of 88%.Serum cTnI is an independent predictor useful for identifying myocardial fibrosis, while plasma NT-proBNP is only associated with myocardial fibrosis on univariate analysis. Combined measurements of serum cTnI with MWT further improve its value in detecting myocardial fibrosis in patients with HOCM.

  10. N-terminal pro-B-type natriuretic peptide and long-term mortality in stable coronary heart disease

    DEFF Research Database (Denmark)

    Kragelund, Charlotte; Grønning, Bjørn; Køber, Lars;

    2005-01-01

    BACKGROUND: The level of the inactive N-terminal fragment of pro-brain (B-type) natriuretic peptide (BNP) is a strong predictor of mortality among patients with acute coronary syndromes and may be a strong prognostic marker in patients with chronic coronary heart disease as well. We assessed...... the relationship between N-terminal pro-BNP (NT-pro-BNP) levels and long-term mortality from all causes in a large cohort of patients with stable coronary heart disease. METHODS: NT-pro-BNP was measured in baseline serum samples from 1034 patients referred for angiography because of symptoms or signs of coronary...... of myocardial infarction, angina, hypertension, diabetes, or chronic heart failure; creatinine clearance rate; body-mass index; smoking status; plasma lipid levels; LVEF; and the presence or absence of clinically significant coronary artery disease on angiography. CONCLUSIONS: NT-pro-BNP is a marker of long...

  11. On B-type open-closed Landau-Ginzburg theories defined on Calabi-Yau Stein manifolds

    CERN Document Server

    Babalic, Mirela; Lazaroiu, Calin Iuliu; Tavakol, Mehdi

    2016-01-01

    We consider the bulk algebra and topological D-brane category arising from the differential model of the open-closed B-type topological Landau-Ginzburg theory defined by a pair $(X,W)$, where $X$ is a non-compact Calabi-Yau manifold and $W$ has compact critical set. When $X$ is a Stein manifold (but not restricted to be a domain of holomorphy), we extract equivalent descriptions of the bulk algebra and of the category of topological D-branes which are constructed using only the analytic space associated to $X$. In particular, we show that the D-brane category is described by projective matrix factorizations defined over the ring of holomorphic functions of $X$. We also discuss simplifications of the analytic models which arise when $X$ is holomorphically parallelizable and illustrate these analytic models in a few classes of examples.

  12. Prognostic value of B-type natriuretic peptide in surgical palliation of children with single-ventricle congenital heart disease.

    Science.gov (United States)

    Berry, J G; Askovich, B; Shaddy, R E; Hawkins, J A; Cowley, C G

    2008-01-01

    The objective of this prospective study was to assess the prognostic role of perioperative B-type natriuretic peptide (BNP) levels in infants and children with single-ventricle congenital heart disease undergoing Norwood, bidirectional cavopulmonary anastomosis (BCPA), or Fontan operation. BNP levels were measured at baseline, after cardiopulmonary bypass, 6 to 12 hours after surgery, and then daily until indwelling vascular catheters were removed. Outcome measures included length of mechanical ventilation, inotropic support, and hospital stay. Twenty subjects underwent 23 surgical procedures (13 Norwood, 5 BCPA, and 5 Fontan). BNP levels were significantly higher in patients undergoing a Norwood procedure compared with a BCPA or Fontan procedure (p extubation was observed in 92% of patients undergoing a Norwood procedure. Early postoperative BNP levels correlate significantly with the ensuing duration of inotropic support and length of hospitalization. An increase in BNP after extubation may be reflective of the degree of underlying cardiopulmonary instability. Further investigation is necessary to define this important relation.

  13. Isolation and Synthesis of Laxaphycin B-Type Peptides: A Case Study and Clues to Their Biosynthesis

    Directory of Open Access Journals (Sweden)

    Louis Bornancin

    2015-12-01

    Full Text Available The laxaphyci’s B family constitutes a group of five related cyclic lipopeptides isolated from diverse cyanobacteria from all around the world. This group shares a typical structure of 12 amino acids from the l and d series, some of them hydroxylated at the beta position, and all containing a rare beta-amino decanoic acid. Nevertheless, they can be differentiated due to slight variations in the composition of their amino acids, but the configuration of their alpha carbon remains conserved. Here, we provide the synthesis and characterization of new laxaphycin B-type peptides. In doing so we discuss how the synthesis of laxaphycin B and analogues was developed. We also isolate minor acyclic laxaphycins B, which are considered clues to their biosynthesis.

  14. Isolation and Synthesis of Laxaphycin B-Type Peptides: A Case Study and Clues to Their Biosynthesis.

    Science.gov (United States)

    Bornancin, Louis; Boyaud, France; Mahiout, Zahia; Bonnard, Isabelle; Mills, Suzanne C; Banaigs, Bernard; Inguimbert, Nicolas

    2015-12-05

    The laxaphyci's B family constitutes a group of five related cyclic lipopeptides isolated from diverse cyanobacteria from all around the world. This group shares a typical structure of 12 amino acids from the l and d series, some of them hydroxylated at the beta position, and all containing a rare beta-amino decanoic acid. Nevertheless, they can be differentiated due to slight variations in the composition of their amino acids, but the configuration of their alpha carbon remains conserved. Here, we provide the synthesis and characterization of new laxaphycin B-type peptides. In doing so we discuss how the synthesis of laxaphycin B and analogues was developed. We also isolate minor acyclic laxaphycins B, which are considered clues to their biosynthesis.

  15. Thermal expansion behavior of A- and B-type amylose crystals in the low-temperature region.

    Science.gov (United States)

    Kobayashi, Kayoko; Kimura, Satoshi; Naito, Philip-Kunio; Togawa, Eiji; Wada, Masahisa

    2015-10-20

    The thermal expansion behaviors of A-type and B-type amylose crystals, which were prepared by recrystallization of short amylose chains synthesized by phosphorylase, were investigated using synchrotron X-ray powder diffraction between 100 and 300K. For both types of crystals, the room-temperature phase (RT phase), which is the usually observed phase, transitioned to a low-temperature phase (LT phase), on cooling. The phase transitions took place reversibly with rapid changes in the unit-cell parameters around 200-270K. The differences between the RT and LT phase were investigated using solid-state (13)C NMR spectroscopy, which revealed there were changes in molecular chain conformations. These results suggest that the phase transition of water molecules on the crystalline surfaces affects the thermal behavior and structure of polysaccharide crystals.

  16. The role of B-type natriuretic peptide in the diagnosis and treatment of decompensated heart failure

    Institute of Scientific and Technical Information of China (English)

    Michael J. Gallagher; Peter A. McCullough

    2004-01-01

    Heart failure (HF) is a common disease associated with increasing age. B-type natriuretic peptide (BNP), is a cardiac neurohormone, and is released as prepro BNP and then enzyrnatically cleaved to the Ntenninal-proBNP (NT-proBNP) and BNP upon ventricular myocyte stretch. Blood measurements of BNP have been used to identify patients with I-IF. The BNP assay is currently used as a diagnostic and prognostic aid in HF. In general, a BNP level below 100 pg/mL excludes acutely decompensated HF and levels > 500 pg/ml indicate decompensation. Recombinant human BNP (hBNP, nesiritide) is an approved intravenous treatment for acute,decompensated -HF. Nesiritide given in supraphysiologic doses causes vasodilation, natriuresis, diuresis, and improved symptoms over the course of a 48-hour infusion. This paper will sort out the literature concerning the use of this peptide both as a diagnostic test and as an intravenous therapy.

  17. The telomeric protein AKTIP interacts with A- and B-type lamins and is involved in regulation of cellular senescence

    Science.gov (United States)

    Burla, Romina; Carcuro, Mariateresa; Torre, Mattia La; Fratini, Federica; Crescenzi, Marco; D'Apice, Maria Rosaria; Spitalieri, Paola; Raffa, Grazia Daniela; Astrologo, Letizia; Lattanzi, Giovanna; Cundari, Enrico; Raimondo, Domenico; Biroccio, Annamaria; Gatti, Maurizio

    2016-01-01

    AKTIP is a shelterin-interacting protein required for replication of telomeric DNA. Here, we show that AKTIP biochemically interacts with A- and B-type lamins and affects lamin A, but not lamin C or B, expression. In interphase cells, AKTIP localizes at the nuclear rim and in discrete regions of the nucleoplasm just like lamins. Double immunostaining revealed that AKTIP partially co-localizes with lamin B1 and lamin A/C in interphase cells, and that proper AKTIP localization requires functional lamin A. In mitotic cells, AKTIP is enriched at the spindle poles and at the midbody of late telophase cells similar to lamin B1. AKTIP-depleted cells show senescence-associated markers and recapitulate several aspects of the progeroid phenotype. Collectively, our results indicate that AKTIP is a new player in lamin-related processes, including those that govern nuclear architecture, telomere homeostasis and cellular senescence. PMID:27512140

  18. Mechanical stretch up-regulates the B-type natriuretic peptide system in human cardiac fibroblasts: a possible defense against transforming growth factor-ß mediated fibrosis

    LENUS (Irish Health Repository)

    Watson, Chris J

    2012-07-07

    AbstractBackgroundMechanical overload of the heart is associated with excessive deposition of extracellular matrix proteins and the development of cardiac fibrosis. This can result in reduced ventricular compliance, diastolic dysfunction, and heart failure. Extracellular matrix synthesis is regulated primarily by cardiac fibroblasts, more specifically, the active myofibroblast. The influence of mechanical stretch on human cardiac fibroblasts’ response to pro-fibrotic stimuli, such as transforming growth factor beta (TGFβ), is unknown as is the impact of stretch on B-type natriuretic peptide (BNP) and natriuretic peptide receptor A (NPRA) expression. BNP, acting via NPRA, has been shown to play a role in modulation of cardiac fibrosis.Methods and resultsThe effect of cyclical mechanical stretch on TGFβ induction of myofibroblast differentiation in primary human cardiac fibroblasts and whether differences in response to stretch were associated with changes in the natriuretic peptide system were investigated. Cyclical mechanical stretch attenuated the effectiveness of TGFβ in inducing myofibroblast differentiation. This finding was associated with a novel observation that mechanical stretch can increase BNP and NPRA expression in human cardiac fibroblasts, which could have important implications in modulating myocardial fibrosis. Exogenous BNP treatment further reduced the potency of TGFβ on mechanically stretched fibroblasts.ConclusionWe postulate that stretch induced up-regulation of the natriuretic peptide system may contribute to the observed reduction in myofibroblast differentiation.

  19. Is N-terminal pro B-type natriuretic peptide (NT-proBNP) a useful screening test for angiographic findings in patients with stable coronary disease?

    DEFF Research Database (Denmark)

    Kragelund, Charlotte; Grønning, Bjørn; Omland, Torbjørn;

    2006-01-01

    BACKGROUND: Whether N-terminal pro B-type natriuretic peptide (NT-proBNP) is a useful screening tool for angiographic coronary artery disease in patients with angina is not known. Therefore, the purpose of this study was to assess the diagnostic test performance of NT-proBNP in detecting coronary......). The ability of NT-proBNP in detecting clinically significant coronary disease at angiography was modest, however, with sensitivity of 0.61, specificity 0.60, accuracy 61 (95% CI 58-64), positive likelihood ratio 1.5 (95% CI 1.3-1.8), negative likelihood ratio 0.7 (95% CI 0.6-0.8), and area under the ROC curve...... atherosclerotic lesions, as assessed by coronary angiography. METHODS: We examined 1034 patients referred for diagnostic angiography because of symptoms or signs of coronary artery disease. The diagnostic value of NT-proBNP in predicting clinically significant coronary disease was assessed. RESULTS: In a multiple...

  20. 纯棉织物B型活性印花冷堆固色%Cold print-batch process of cotton fabric with B type reactive dyes

    Institute of Scientific and Technical Information of China (English)

    陈友波; 唐群; 吴君风

    2012-01-01

    Cotton printing is carried out with cold batching fixation using B-type reactive dyes. In this process, alkaline is first padded into high count polyester fabric, and then the reactive printed cotton fabric is batched and dwelled together with the treated polyester fabric. The factors affecting the printing effects are analyzed, including specifications of polyester fabric, the padder pressure and thickener types. Cold batching fixation and steaming fixation are compared. It is found that the cold batching fixation features high color yield of up to 90% and good color fastness.%纯棉织物用异双活性基的B型活性染料印花后冷堆固色,通过将固色碱液施于经纬密度较高的涤纶布上,再将其与印有活性染料的纯棉织物一起打卷,使该含有碱剂的涤纶织物衬于棉织物之中.通过试验,分析了影响印花效果的因素,包括涤纶的组织规格、轧车压力、糊料种类等;比较了冷堆固色与汽蒸固色的效果,发现B型活性染料采用冷堆固色方法,固色率可达90%,且色牢度好.

  1. Data on cytochrome c oxidase assembly in mice and human fibroblasts or tissues induced by SURF1 defect.

    Science.gov (United States)

    Kovářová, Nikola; Pecina, Petr; Nůsková, Hana; Vrbacký, Marek; Zeviani, Massimo; Mráček, Tomáš; Viscomi, Carlo; Houštěk, Josef

    2016-06-01

    This paper describes data related to a research article entitled "Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects" [1]. This paper includes data of the quantitative analysis of individual forms of respiratory chain complexes I, III and IV present in SURF1 knockout (SURF1 (-/-) ) and control (SURF1 (+/+) ) mouse fibroblasts and tissues and in fibroblasts of human control and patients with SURF1 gene mutation. Also it includes data demonstrating response of complex IV, cytochrome c oxidase (COX), to reversible inhibition of mitochondrial translation in SURF1 (-/-) mouse and SURF1 patient fibroblast cell lines.

  2. Norharman (beta-carboline) as a potent inhibitory ligand for steroidogenic cytochromes P450 (CYP11 and CYP17).

    Science.gov (United States)

    Kühn-Velten, W N

    1993-11-30

    Norharman (beta-carboline, a so-called mammalian alkaloid) is identified as a high-affinity type II ligand for two steroidogenic cytochromes P450, viz. CYP11 in rat adrenal mitochondria and CYP17 in rat testicular microsomes. Progesterone binding to CYP17 is competitively inhibited, with Ki = 2.6 microM norharman, whereas harman, tetrahydronorharman and tetrahydroharman are nearly ineffective. The potential role of norharman as an endogenous modulator of steroid hormone biosynthesis and as a basic drug for development of more specific cytochrome P450 inhibitors is emphasized.

  3. Structures of Cytochrome b 5 Mutated at the Charged Surface-Residues and Their Interactions with Cytochrome c

    Institute of Scientific and Technical Information of China (English)

    WU,Jian(邬键); WANG,Yun-Hua(王韵华); GAN,Jian-Hua(甘建华); WANG,Wen-Hu(王文虎); SUN,Bing-Yun(孙炳耘); HUANG,Zhong-Xian(黄仲贤); XIA,Zong-Xiang(夏宗芗)

    2002-01-01

    Glu44, Glu48, Glu56 and Asp60 are the negatively charged residues located at the molecular surface of cytochrome b5@Two mutants of cytochrome b5 were prepared, in which two or all of these four residues were mutated to alanines. The mutations give rise to slightly positive shifts of the redox potentials of cytochrome b5 and obvious decrease of the cytochrome b5-cytochrome c binding constants and electron transfer rates. The crystal structures of the two mutants were determined at 0.18 nm resolution, showing no alteration in overall structures and exhibiting slight chages in the local conformations around the mutation sites as compared with the wild-type protein. Based on the crystal structure of the quadruple-site mutant, a model for the binding of this mutant with cytochrome c is proposed, which involves the salt bridges from Glu37, Glu38 and heme propionate of cytochrome b5 to three lysines of cytochrome c and can well account for the properties and behaviors of this mutant.

  4. Atomic structure of the apoptosome: mechanism of cytochrome c- and dATP-mediated activation of Apaf-1.

    Science.gov (United States)

    Zhou, Mengying; Li, Yini; Hu, Qi; Bai, Xiao-Chen; Huang, Weiyun; Yan, Chuangye; Scheres, Sjors H W; Shi, Yigong

    2015-11-15

    The apoptotic protease-activating factor 1 (Apaf-1) controls the onset of many known forms of intrinsic apoptosis in mammals. Apaf-1 exists in normal cells as an autoinhibited monomer. Upon binding to cytochrome c and dATP, Apaf-1 oligomerizes into a heptameric complex known as the apoptosome, which recruits and activates cell-killing caspases. Here we present an atomic structure of an intact mammalian apoptosome at 3.8 Å resolution, determined by single-particle, cryo-electron microscopy (cryo-EM). Structural analysis, together with structure-guided biochemical characterization, uncovered how cytochrome c releases the autoinhibition of Apaf-1 through specific interactions with the WD40 repeats. Structural comparison with autoinhibited Apaf-1 revealed how dATP binding triggers a set of conformational changes that results in the formation of the apoptosome. Together, these results constitute the molecular mechanism of cytochrome c- and dATP-mediated activation of Apaf-1.

  5. Reduction of low potential electron acceptors requires the CbcL inner membrane cytochrome of Geobacter sulfurreducens.

    Science.gov (United States)

    Zacharoff, Lori; Chan, Chi Ho; Bond, Daniel R

    2016-02-01

    The respiration of metals by the bacterium Geobacter sulfurreducens requires electrons generated by metabolism to pass from the interior of the cell to electron acceptors beyond the cell membranes. The G. sulfurreducens inner membrane multiheme c-type cytochrome ImcH is required for respiration to extracellular electron acceptors with redox potentials greater than -0.1 V vs. SHE, but ImcH is not essential for electron transfer to lower potential acceptors. In contrast, deletion of cbcL, encoding an inner membrane protein consisting of b-type and multiheme c-type cytochrome domains, severely affected reduction of low potential electron acceptors such as Fe(III)-oxides and electrodes poised at -0.1 V vs. SHE. Catalytic cyclic voltammetry of a ΔcbcL strain growing on poised electrodes revealed a 50 mV positive shift in driving force required for electron transfer out of the cell. In non-catalytic conditions, low-potential peaks present in wild type biofilms were absent in ∆cbcL mutants. Expression of cbcL in trans increased growth at low redox potential and restored features to cyclic voltammetry. This evidence supports a model where CbcL is a component of a second electron transfer pathway out of the G. sulfurreducens inner membrane that dominates when redox potential is at or below -0.1 V vs. SHE.

  6. Prediction of cytochrome P450 mediated metabolism

    DEFF Research Database (Denmark)

    Olsen, Lars; Oostenbrink, Chris; Jørgensen, Flemming Steen

    2015-01-01

    Cytochrome P450 enzymes (CYPs) form one of the most important enzyme families involved in the metabolism of xenobiotics. CYPs comprise many isoforms, which catalyze a wide variety of reactions, and potentially, a large number of different metabolites can be formed. However, it is often hard...... to rationalize what metabolites these enzymes generate. In recent years, many different in silico approaches have been developed to predict binding or regioselective product formation for the different CYP isoforms. These comprise ligand-based methods that are trained on experimental CYP data and structure-based...... methods that consider how the substrate is oriented in the active site or/and how reactive the part of the substrate that is accessible to the heme group is. We will review key aspects for various approaches that are available to predict binding and site of metabolism (SOM), what outcome can be expected...

  7. Flower colour and cytochromes P450.

    Science.gov (United States)

    Tanaka, Yoshikazu; Brugliera, Filippa

    2013-02-19

    Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H) and thus they play a crucial role in the determination of flower colour. F3'H and F3'5'H mostly belong to CYP75B and CYP75A, respectively, except for the F3'5'Hs in Compositae that were derived from gene duplication of CYP75B and neofunctionalization. Roses and carnations lack blue/violet flower colours owing to the deficiency of F3'5'H and therefore lack the B-ring-trihydroxylated anthocyanins based upon delphinidin. Successful redirection of the anthocyanin biosynthesis pathway to delphinidin was achieved by expressing F3'5'H coding regions resulting in carnations and roses with novel blue hues that have been commercialized. Suppression of F3'5'H and F3'H in delphinidin-producing plants reduced the number of hydroxyl groups on the anthocyanidin B-ring resulting in the production of monohydroxylated anthocyanins based on pelargonidin with a shift in flower colour to orange/red. Pelargonidin biosynthesis is enhanced by additional expression of a dihydroflavonol 4-reductase that can use the monohydroxylated dihydrokaempferol (the pelargonidin precursor). Flavone synthase II (FNSII)-catalysing flavone biosynthesis from flavanones is also a P450 (CYP93B) and contributes to flower colour, because flavones act as co-pigments to anthocyanins and can cause blueing and darkening of colour. However, transgenic plants expression of a FNSII gene yielded paler flowers owing to a reduction of anthocyanins because flavanones are precursors of anthocyanins and flavones.

  8. Separation, purification, and properties of cytochrome P-450 from uninduced rat liver microsomes for the studies of metabolism of environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Dialameh, G.H. (Tehran Univ. of Medical Sciences (Iran))

    1988-09-01

    This study reports the authors present results on the development of a procedure for purification of multiple forms of cytochrome P-450 from un-induced rat liver microsomes. These cytochromes are catalytically active when reconstituted with NADPH-cytochrome c reductase and lipid and exhibit substrate specificities. The presence of four distinct forms of cytochrome P-450 in uninduced rat liver microsomes which is the result of this research report, compared with the presence of six forms in induced animals represent the importance of genetic control of these enzymes for the metabolism and detoxification of environmental chemicals. These metabolite patterns are not only different for the various species, but also among different individuals. The molecular basis for this are genetic and environmental factors, which exhibit interesting evolutionary aspects.

  9. New cytochrome P450 isoforms as cancer biomarkers and targets for chemopreventive and chemotherapeutic agents

    Directory of Open Access Journals (Sweden)

    Hanna Szaefer

    2013-08-01

    Full Text Available Cytochromes P450 (P450 are a multigene family of enzymes possessing a central role in the oxidative metabolism of a wide range of xenobiotics, including anticancer drugs, and endogenous compounds. The activity of different P450 isoforms varies within specific tissues and cell types and is selectively regulated together with their gene expression. Moreover, differential expression of certain P450 isoforms’ genes in tumor cells compared to normal tissues can be observed. This creates the potential for the use of these isozymes as tumor markers or selective prodrug activators. This article discusses the characteristics and function of five isoforms of cytochrome P450 (P450 1B1, P450 2W1, P450 2S1, P450 2R1, P450 2U1 that could be potential targets for tumor therapeutic and preventive strategies. These isoforms have been chosen because their level of expression in tumor tissues is definitely higher than in normal tissues.

  10. Interaction of apo cytochrome c with sulfonated polystyrene nanoparticles.

    Science.gov (United States)

    Liang, Li; Yao, Ping; Gong, Jie; Jiang, Ming

    2004-04-13

    Stable nanoparticle dispersion in aqueous solutions was obtained with partially sulfonated polystyrene. The hydrophobic association of the backbone chains and phenyl groups is balanced by the electrostatic repulsion of the sulfonate groups on the particle surface. The size distribution of the sulfonated polystyrene particles in relation to concentration, degree of sulfonation and chain length, and pH was characterized by dynamic laser light-scattering. The structure and morphology of the particles were characterized with fluorescence and atom force microscopy. Highly sulfonated polystyrene particles can form large complex particles with positively charged protein, apo cytochrome c. Dynamic laser light-scattering and atom force microscopy studies show that the size and distribution of the complex particles depend on the relative amount of apo cytochrome c and sulfonated polystyrene. When sulfonated polystyrene is in excess, apo cytochrome c interacts with sulfonated polystyrene particles forming stable complexes and excessive sulfonated polystyrene particles bind to the periphery of the complexes preventing them from further aggregation. When apo cytochrome c is in excess, apo cytochrome c links the complexes forming much larger particles. Fluorescence study demonstrates that the hydrophobicity/hydrophility of the complex particles is relative to the ratio of apo cytochrome c and sulfonated polystyrene, degree of sulfonation, and pH. Apo cytochrome c not only can neutralize the negative charges on the surface of sulfonated polystyrene particles, but may also insert into the cores disrupting the original structure of sulfonated polystyrene particles.

  11. The plastid-localized pfkB-type carbohydrate kinases FRUCTOKINASE-LIKE 1 and 2 are essential for growth and development of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Gilkerson Jonathan

    2012-07-01

    Full Text Available Abstract Background Transcription of plastid-encoded genes requires two different DNA-dependent RNA polymerases, a nuclear-encoded polymerase (NEP and plastid-encoded polymerase (PEP. Recent studies identified two related pfkB-type carbohydrate kinases, named FRUCTOKINASE-LIKE PROTEIN (FLN1 and FLN2, as components of the thylakoid bound PEP complex in both Arabidopsis thaliana and Sinapis alba (mustard. Additional work demonstrated that RNAi-mediated reduction in FLN expression specifically diminished transcription of PEP-dependent genes. Results Here, we report the characterization of Arabidopsis FLN knockout alleles to examine the contribution of each gene in plant growth, chloroplast development, and in mediating PEP-dependent transcription. We show that fln plants have severe phenotypes with fln1 resulting in an albino phenotype that is seedling lethal without a source of exogenous carbon. In contrast, fln2 plants display chlorosis prior to leaf expansion, but exhibit slow greening, remain autotrophic, can grow to maturity, and set viable seed. fln1 fln2 double mutant analysis reveals haplo-insufficiency, and fln1 fln2 plants have a similar, but more severe phenotype than either single mutant. Normal plastid development in both light and dark requires the FLNs, but surprisingly skotomorphogenesis is unaffected in fln seedlings. Seedlings genetically fln1-1 with dexamethasone-inducible FLN1-HA expression at germination are phenotypically indistinguishable from wild-type. Induction of FLN-HA after 24 hours of germination cannot rescue the mutant phenotype, indicating that the effects of loss of FLN are not always reversible. Examination of chloroplast gene expression in fln1-1 and fln2-1 by qRT-PCR reveals that transcripts of PEP-dependent genes were specifically reduced compared to NEP-dependent genes in both single mutants. Conclusions Our results demonstrate that each FLN protein contributes to wild type growth, and acting additively are

  12. The subunit composition and function of mammalian cytochrome c oxidase.

    Science.gov (United States)

    Kadenbach, Bernhard; Hüttemann, Maik

    2015-09-01

    Cytochrome c oxidase (COX) from mammals and birds is composed of 13 subunits. The three catalytic subunits I-III are encoded by mitochondrial DNA, the ten nuclear-coded subunits (IV, Va, Vb, VIa, VIb, VIc, VIIa, VIIb, VIIc, VIII) by nuclear DNA. The nuclear-coded subunits are essentially involved in the regulation of oxygen consumption and proton translocation by COX, since their removal or modification changes the activity and their mutation causes mitochondrial diseases. Respiration, the basis for ATP synthesis in mitochondria, is differently regulated in organs and species by expression of tissue-, developmental-, and species-specific isoforms for COX subunits IV, VIa, VIb, VIIa, VIIb, and VIII, but the holoenzyme in mammals is always composed of 13 subunits. Various proteins and enzymes were shown, e.g., by co-immunoprecipitation, to bind to specific COX subunits and modify its activity, but these interactions are reversible, in contrast to the tightly bound 13 subunits. In addition, the formation of supercomplexes with other oxidative phosphorylation complexes has been shown to be largely variable. The regulatory complexity of COX is increased by protein phosphorylation. Up to now 18 phosphorylation sites have been identified under in vivo conditions in mammals. However, only for a few phosphorylation sites and four nuclear-coded subunits could a specific function be identified. Research on the signaling pathways leading to specific COX phosphorylations remains a great challenge for understanding the regulation of respiration and ATP synthesis in mammalian organisms. This article reviews the function of the individual COX subunits and their isoforms, as well as proteins and small molecules interacting and regulating the enzyme.

  13. Isolation and Characterization of a Hybrid Respiratory Supercomplex Consisting of Mycobacterium tuberculosis Cytochrome bcc and Mycobacterium smegmatis Cytochrome aa3.

    Science.gov (United States)

    Kim, Mi-Sun; Jang, Jichan; Ab Rahman, Nurlilah Binte; Pethe, Kevin; Berry, Edward A; Huang, Li-Shar

    2015-06-05

    Recently, energy production pathways have been shown to be viable antitubercular drug targets to combat multidrug-resistant tuberculosis and eliminate pathogen in the dormant state. One family of drugs currently under development, the imidazo[1,2-a]pyridine derivatives, is believed to target the pathogen's homolog of the mitochondrial bc1 complex. This complex, denoted cytochrome bcc, is highly divergent from mitochondrial Complex III both in subunit structure and inhibitor sensitivity, making it a good target for drug development. There is no soluble cytochrome c in mycobacteria to transport electrons from the bcc complex to cytochrome oxidase. Instead, the bcc complex exists in a "supercomplex" with a cytochrome aa3-type cytochrome oxidase, presumably allowing direct electron transfer. We describe here purification and initial characterization of the mycobacterial cytochrome bcc-aa3 supercomplex using a strain of M. smegmatis that has been engineered to express the M. tuberculosis cytochrome bcc. The resulting hybrid supercomplex is stable during extraction and purification in the presence of dodecyl maltoside detergent. It is hoped that this purification procedure will potentiate functional studies of the complex as well as crystallographic studies of drug binding and provide structural insight into a third class of the bc complex superfamily.

  14. Heterologous synthesis of cytochrome c' by Escherichia coli is not dependent on the System I cytochrome c biogenesis machinery.

    Science.gov (United States)

    Inoue, Hiroki; Wakai, Satoshi; Nishihara, Hirofumi; Sambongi, Yoshihiro

    2011-07-01

    Hydrogenophilus thermoluteolus cytochrome c' (PHCP) has typical spectral properties previously observed for other cytochromes c', which comprise Ambler's class II cytochromes c. The PHCP protein sequence (135 amino acids) deduced from the cloned gene is the most homologous (55% identity) to that of cytochrome c' from Allochromatium vinosum (AVCP). These findings indicate that PHCP forms a four-helix bundle structure, similar to AVCP. Strikingly, PHCP with a covalently bound heme was heterologously synthesized in the periplasm of Escherichia coli strains deficient in the DsbD protein, a component of the System I cytochrome c biogenesis machinery. The heterologous synthesis of PHCP by aerobically growing E. coli also occurred without a plasmid carrying the genes for Ccm proteins, other components of the System I machinery. Unlike Ambler's class I general cytochromes c, the synthesis of PHCP is not dependent on the System I machinery and exhibits similarity to that of E. coli periplasmic cytochrome b(562), a 106-residue four-helix bundle.

  15. High-performance α-Fe/Pr2Fe14B-type nanocomposite magnets fabricated by direct melt spinning

    Institute of Scientific and Technical Information of China (English)

    YANG Bai; ZHANG Lei; SHEN Baogen; ZHAO Tongyun; YU Ronghai

    2013-01-01

    High-performance α-Fe/Pr2Fe14B-type nanocomposite magnets based on the compositions of Pr8Fe86B6 microalloyed with Co,Nb and C were fabricated by direct melt spinning.The coercivity was greatly improved from 5.5 kOe for the Pr8Fe86B6 ribbons to 7.4 kOe for the Pr8Fe85NbB5C ribbons.The balanced high coercivity and remanence were obtained in Pr8Fe75Co10NbB5C ribbons due to the Co substitution for Fe,which led to the significant improvement of magnetic properties in these ribbons.A remanence ratio of 0.82,a coercive field of 6.6 kOe and a maximum energy product of 26.2 MGOe in melt-spun Pr8Fe75Co10NbB5C ribbons were obtained at room temperature.

  16. Multiplex detection of B-type natriuretic peptide, cardiac troponin I and C-reactive protein with photonic suspension array.

    Directory of Open Access Journals (Sweden)

    Wenbin Lu

    Full Text Available A novel photonic suspension array has been developed for multiplex immunoassay. The carriers of this array were silica colloidal crystal beads (SCCBs. The codes of these carriers have characteristic reflection peaks originating from their structural periodicity; therefore they do not suffer from fading, bleaching, quenching or chemical instability. In addition, the fluorescence background of SCCBs is negligible because no fluorescence materials or dyes are involved. With a sandwich method, the proposed suspension array was used for simultaneous multiplex detection of heart failure (HF and coronary heart disease (CAD biomarkers in one test tube. The results showed that the three biomarkers: cardiac troponin I (cTnI, C-reactive protein (CRP and B-type natriuretic peptide (BNP could be assayed in the ranges of 0.1-500 ng/ml, 1-500 mg/L and 0.02-50 ng/ml with detection limits of 0.01 ng/ml, 0.36 mg/L and 0.004 ng/ml at 3σ, respectively. There were no significant differences between the photonic suspension array and traditional parallel single-analyte test. This novel method demonstrated acceptable accuracy, high detection sensitivity and reproducibility and excellent storage stability. This technique provides a new strategy for low cost, automated, and simultaneous multiplex immunoassays of bio-markers.

  17. B-type Natriuretic Peptide Assay in Differentiating Congestive Heart Failure from Lung Disease in Patients Presenting with Dyspnea.

    Science.gov (United States)

    Islam, M A; Bari, M S; Islam, M N; Bari, M A; Siddique, S R; Islam, M Z; Begum, M S; Ahammed, S U; Rahman, M A

    2016-07-01

    This cross-sectional analytical study was conducted in Cardiology & Medicine Department of Mymensingh Medical College Hospital. After fulfilling the exclusion & inclusion criteria, B-type natriuretic peptide concentrations were measured in a convenience sample of 100 predominantly male (94%) dyspnic patients who got admitted in Cardiology & Medicine Department of Mymensingh Medical College & Hospital from November 2013 to October 2014. The diagnosis of Congestive Heart Failure (CHF) was based on generally accepted Framingham criteria with corroborative information including hospital course (response to diuretics, vasodilators, inotropes or hemodynamic monitoring) and results of further cardiac testing, including echocardiography. Patients with right heart failure from cor pulmonale were classified as having CHF. Pulmonary disease was confirmed by using the following diagnostic tools: i) A chest X-ray without signs of heart enlargement or pulmonary venous hypertension or a chest X-ray with signs of chronic obstructive lung disease, ii) Normal heart function as seen by echocardiography, iii) Abnormal pulmonary function tests or follow-up results and iv) A positive response to treatment with steroids, nebulizers or antibiotics in hospital. Patients with CHF (n=50) had mean BNP level 1146.72pg/ml (range 103 to 5000pg/ml), which is significantly higher than the group of patients with a final diagnosis of pulmonary disease (n=50) whose BNP was 34pg/ml (range 10 to 90pg/ml) (pcongestive heart failure from lung disease in patients presenting with dyspnea.

  18. Improvement of enantioselectivity of the B-type halohydrin hydrogen-halide-lyase from Corynebacterium sp. N-1074.

    Science.gov (United States)

    Watanabe, Fumiaki; Yu, Fujio; Ohtaki, Akashi; Yamanaka, Yasuaki; Noguchi, Keiichi; Odaka, Masafumi; Yohda, Masafumi

    2016-09-01

    Halohydrin hydrogen-halide-lyase (H-Lyase) is a bacterial enzyme involved in the degradation of halohydrins. This enzyme catalyzes the intramolecular nucleophilic displacement of a halogen by a vicinal hydroxyl group in halohydrins, producing the corresponding epoxides. The H-Lyases have been classified into A, B and C subtypes based on amino acid sequence similarities. These enzymes have attracted much attention as industrial catalysts in the synthesis of chiral chemicals from prochiral halohydrins. In the present study, we constructed mutants of B-type H-Lyase from Corynebacterium sp. N-1074 (HheB) displaying higher enantioselectivity by structure-based site-directed mutagenesis and random mutagenesis. A triple mutant of HheB exhibited 98.5% enantioselectivity, the highest ever reported, toward (R)-4-chloro-3-hydroxy-butyronitrile production, with the yield reaching approximately two-fold that of the wild-type enzyme. We discuss the structural basis of the high enantioselectivity and productivity of the mutant by comparing the crystal structures of the mutant HheB and the wild-type enzyme in complex with or without the substrate analogue.

  19. The IACOB project: III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars

    CERN Document Server

    Simón-Díaz, S; Castro, N; Herrero, A; Aerts, C; Puls, J; Telting, J; Grassitelli, L

    2016-01-01

    We aim to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars to evaluate its physical origin. We use high-resolution spectra of ~430 stars with spectral types in the range O4-B9 (all luminosity classes). We characterize the line-broadening of adequate diagnostic metal lines using a combined FT and GOF technique. We perform a quantitative spectroscopic analysis of the whole sample using automatic tools coupled with a huge grid of FASTWIND models. We also incorporate quantitative information about line asymmetries to our observational description of the characteristics of the line-profiles, and present a comparison of the shape and type of line-profile variability found in a small sample of O stars and B supergiants with still undefined pulsational properties and B main sequence stars with variable line-profiles. We present a homogeneous and statistically significant overview of the (single snapshot) line-broadening properties of stars in the whole O and B star doma...

  20. Novel cytochrome P450, cyp6a17, is required for temperature preference behavior in Drosophila.

    Directory of Open Access Journals (Sweden)

    Jongkyun Kang

    Full Text Available Perception of temperature is an important brain function for organisms to survive. Evidence suggests that temperature preference behavior (TPB in Drosophila melanogaster, one of poikilothermal animals, is regulated by cAMP-dependent protein kinase (PKA signaling in mushroom bodies of the brain. However, downstream targets for the PKA signaling in this behavior have not been identified. From a genome-wide search for the genes regulated by PKA activity in the mushroom bodies, we identified the cyp6a17 Cytochrome P450 gene as a new target for PKA. Our detailed analysis of mutants by genetic, molecular and behavioral assays shows that cyp6a17 is essential for temperature preference behavior. cyp6a17 expression is enriched in the mushroom bodies of the adult brain. Tissue-specific knockdown and rescue experiments demonstrate that cyp6a17 is required in the mushroom bodies for normal temperature preference behavior. This is the first study, to our knowledge, to show PKA-dependent expression of a cytochrome P450 gene in the mushroom bodies and its role as a key factor for temperature preference behavior. Taken together, this study reveals a new PKA-Cytochrome P450 pathway that regulates the temperature preference behavior.

  1. Dual Targeting of a Mitochondrial Protein: The Case Study of Cytochrome C1

    Institute of Scientific and Technical Information of China (English)

    Anja R(o)diger; Bianca Baudisch; Uwe Langner; Ralf Bernd Kl(o)sgen

    2011-01-01

    As a result of the endosymbiotic gene transfer, the majority of proteins of mitochondria and chloroplasts is encoded in the nucleus and synthesized in the cytosol as precursor molecules carrying N-terminal transit peptides for the transport into the respective target organelle. In most instances, transport takes place into either mitochondria or chlor-oplasts, although a few examples of dual targeting into both organelles have been described. Here, we show by a com-bination of three different experimental strategies that also cytochrome c of potato, a component of the respiratory electron transport chain, is imported not only into mitochondria, but also into plastids. In organello import experiments with isolated mitochondria and chloroplasts, which were analyzed in both single and mixed organelle assays, demonstrate that the processing products accumulating after import within the two endosymbiotic organelles are different in size. Dual targeting of cytochrome c is observed also in vivo, after biolistic transformation of leaf epidermal cells with suitable reporter constructions. Finally, Western analyses employing cytochrome c-specific antiserum provide evidence that the protein accumulates in significant amounts in mitochondria and chloroplasts of both pea and spinach. The possible consequences of our findings on the relevance of the dual targeting phenomenon are discussed.

  2. Characterization and expression of the cytochrome P450 gene family in diamondback moth, Plutella xylostella (L.).

    Science.gov (United States)

    Yu, Liying; Tang, Weiqi; He, Weiyi; Ma, Xiaoli; Vasseur, Liette; Baxter, Simon W; Yang, Guang; Huang, Shiguo; Song, Fengqin; You, Minsheng

    2015-03-10

    Cytochrome P450 monooxygenases are present in almost all organisms and can play vital roles in hormone regulation, metabolism of xenobiotics and in biosynthesis or inactivation of endogenous compounds. In the present study, a genome-wide approach was used to identify and analyze the P450 gene family of diamondback moth, Plutella xylostella, a destructive worldwide pest of cruciferous crops. We identified 85 putative cytochrome P450 genes from the P. xylostella genome, including 84 functional genes and 1 pseudogene. These genes were classified into 26 families and 52 subfamilies. A phylogenetic tree constructed with three additional insect species shows extensive gene expansions of P. xylostella P450 genes from clans 3 and 4. Gene expression of cytochrome P450s was quantified across multiple developmental stages (egg, larva, pupa and adult) and tissues (head and midgut) using P. xylostella strains susceptible or resistant to insecticides chlorpyrifos and fiprinol. Expression of the lepidopteran specific CYP367s predominantly occurred in head tissue suggesting a role in either olfaction or detoxification. CYP340s with abundant transposable elements and relatively high expression in the midgut probably contribute to the detoxification of insecticides or plant toxins in P. xylostella. This study will facilitate future functional studies of the P. xylostella P450s in detoxification.

  3. Cyclooxygenase- and cytochrome P450-derived eicosanoids in stroke.

    Science.gov (United States)

    Huang, Hui; Al-Shabrawey, Mohamed; Wang, Mong-Heng

    2016-01-01

    Arachidonic acid (AA) is metabolized by cyclooxygenase (COX) and cytochrome P450 (CYP) enzymes into eicosanoids, which are involved in cardiovascular diseases and stroke. Evidence has demonstrated the important functions of these eicosanoids in regulating cerebral vascular tone, cerebral blood flow, and autoregulation of cerebral circulation. Although COX-2 inhibitors have been suggested as potential treatments for stroke, adverse events, including an increased risk of stroke, occur following long-term use of coxibs. It is important to note that prolonged treatment with rofecoxib increased circulating levels of 20-hydroxyeicosatetraenoic acid (20-HETE), and 20-HETE blockade is a possible strategy to prevent coxib-induced stroke events. It appears that 20-HETE has detrimental effects in the brain, and that its blockade exerts cerebroprotection against ischemic stroke and subarachnoid hemorrhage (SAH). There is clear evidence that activation of EP2 and EP4 receptors exerts cerebroprotection against ischemic stroke. Several elegant studies have contributed to defining the importance of stabilizing the levels of epoxyeicosatrienoic acids (EETs), by inhibiting or deleting soluble epoxide hydrolase (sEH), in stroke research. These reports support the notion that sEH blockade is cerebroprotective against ischemic stroke and SAH. Here, we summarize recent findings implicating these eicosanoid pathways in cerebral vascular function and stroke. We also discuss the development of animal models with targeted gene deletion and specific enzymatic inhibitors in each pathway to identify potential targets for the treatment of ischemic stroke and SAH.

  4. Animal Species Identification by PCR – RFLP of Cytochrome b

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    Tomáš Minarovič

    2010-05-01

    Full Text Available An alternative DNA detection system is based on the polymerase chain reaction (PCR amplification of a segment of the mitochondrial cytochrome b gene. Subsequent cleavage by a restriction enzymes gives rise to a specie-specific pattern on an agarose gel. We used five animal species (Mustela vison, Mustela putorius furo, Sus scrofa domesticus, Oryctolagus cuninculus, Anser anser. Length of PCR product was 359 bp and we used universal primers. Restriction fragment length polymorphism was analyzed by using the restriction endonuclease AluI. Results of cleavage were visualized by using electrophoresis and UV transiluminator. Every animal specie has a unique combination of restriction fragments i.e. Mustela vison 81 bp, 109 bp and 169 bp, Mustela putorius furo 169 bp and 190 bp, Sus scrofa domesticus 115 bp and 244 bp, Oryctolagus cunninculus is not cleaved by AluI so it has whole 359 bp fragment on agarose gel, Anser anser 130 bp and 229 bp. The results suggest that the method of PCR - RFLP is rapid and simple method for identification of species. PCR – RFLP can reliably identify chosen species. Application of genetic methods is very useful for breeding of livestock and protection of biodiversity.

  5. Mechanisms of Electron Transfer in Two Decaheme Cytochromes from a Metal-Reducing Bacterium

    Energy Technology Data Exchange (ETDEWEB)

    Wigginton, Nicholas S.; Rosso, Kevin M.; Hochella, Michael F.

    2007-11-08

    Single-molecule current-voltage (I–V) spectra were collected using a scanning tunneling microscope for two decaheme c-type cytochromes, OmcA and MtrC, which are outer-membrane proteins from the dissimilatory metal-reducing bacterium Shewanella oneidensis. Although the two cytochromes are similar in heme count, charge-carrying amino-acid content, and molecular mass, their I–V spectra are significantly different. The I–V spectra for OmcA show smoothly varying symmetric exponential behavior. These spectra are well fit by a coherent tunneling model that is based on a simple square barrier description of the tunneling junction. In contrast, the I–V spectra for MtrC have pronounced breaks in slope in the positive tip bias range. Two large peaks in the normalized differential conductance spectra of MtrC were fit to a tunneling model that accounts for the possibility of transient population of empty states stabilized by vibrational relaxation. Reorganization energies deduced for the two features are similar to those normally assigned to metal centers in other metalloproteins. Work function measurements of the cytochrome films were used to convert the energies of these two spectral features to the normal hydrogen electrode scale for comparison with the midpoint potential measured using protein film voltammetry, which showed good correspondence. We conclude that MtrC mediates tunneling current by heme orbital participation. The difference in tunneling behavior between OmcA and MtrC suggests distinct physiological functions for the two cytochromes; in contrast to OmcA, MtrC appears to be tuned to a specific operating potential.

  6. Modular assembly of yeast cytochrome oxidase.

    Science.gov (United States)

    McStay, Gavin P; Su, Chen Hsien; Tzagoloff, Alexander

    2013-02-01

    Previous studies of yeast cytochrome oxidase (COX) biogenesis identified Cox1p, one of the three mitochondrially encoded core subunits, in two high-molecular weight complexes combined with regulatory/assembly factors essential for expression of this subunit. In the present study we use pulse-chase labeling experiments in conjunction with isolated mitochondria to identify new Cox1p intermediates and place them in an ordered pathway. Our results indicate that before its assimilation into COX, Cox1p transitions through five intermediates that are differentiated by their compositions of accessory factors and of two of the eight imported subunits. We propose a model of COX biogenesis in which Cox1p and the two other mitochondrial gene products, Cox2p and Cox3p, constitute independent assembly modules, each with its own complement of subunits. Unlike their bacterial counterparts, which are composed only of the individual core subunits, the final sequence in which the mitochondrial modules associate to form the holoenzyme may have been conserved during evolution.

  7. Cytochrome C stabilization and immobilization in aerogels.

    Science.gov (United States)

    Harper-Leatherman, Amanda S; Wallace, Jean Marie; Rolison, Debra R

    2011-01-01

    Sol-gel-derived aerogels are three-dimensional, nanoscale materials that combine large surface areas and high porosities. These traits make them useful for any rate-critical chemical process, particularly sensing or electrochemical applications, once physical or chemical moieties are incorporated into the gels to add their functionality into the ultraporous scaffold. Incorporating biomolecules into aerogels has been challenging due to the inability of most biomolecules to remain structurally intact within the gels during the necessary supercritical fluid processing. However, the heme protein cytochrome c (cyt. c) forms self-organized superstructures around gold (or silver) nanoparticles in buffer that can be encapsulated within silica and processed to form aerogels in which cyt. c retains its characteristic visible absorption. The gold (or silver) nanoparticle-nucleated superstructures protect the majority of the protein from the harsh physicochemical conditions necessary to form an aerogel. The Au∼cyt. c superstructures exhibit rapid gas-phase recognition of nitric oxide (NO) within the aerogel matrix, as facilitated by the high-quality pore structure of the aerogel, and remain viable for weeks at room temperature.

  8. Distribution and physiological effects of B-type allatostatins (myoinhibitory peptides, MIPs) in the stomatogastric nervous system of the crab Cancer borealis.

    Science.gov (United States)

    Szabo, Theresa M; Chen, Ruibing; Goeritz, Marie L; Maloney, Ryan T; Tang, Lamont S; Li, Lingjun; Marder, Eve

    2011-09-01

    The crustacean stomatogastric ganglion (STG) is modulated by a large number of amines and neuropeptides that are found in descending pathways from anterior ganglia or reach the STG via the hemolymph. Among these are the allatostatin (AST) B types, also known as myoinhibitory peptides (MIPs). We used mass spectrometry to determine the sequences of nine members of the AST-B family of peptides that were found in the stomatogastric nervous system of the crab Cancer borealis. We raised an antibody against Cancer borealis allatostatin-B1 (CbAST-B1; VPNDWAHFRGSWa) and used it to map the distribution of CbAST-B1-like immunoreactivity (-LI) in the stomatogastric nervous system. CbAST-B1-LI was found in neurons and neuropil in the commissural ganglia (CoGs), in somata in the esophageal ganglion (OG), in fibers in the stomatogastric nerve (stn), and in neuropilar processes in the STG. CbAST-B1-LI was blocked by preincubation with 10(-6) M CbAST-B1 and was partially blocked by lower concentrations. Electrophysiological recordings of the effects of CbAST-B1, CbAST-B2, and CbAST-B3 on the pyloric rhythm of the STG showed that all three peptides inhibited the pyloric rhythm in a state-dependent manner. Specifically, all three peptides at 10(-8) M significantly decreased the frequency of the pyloric rhythm when the initial frequency of the pyloric rhythm was below 0.6 Hz. These data suggest important neuromodulatory roles for the CbAST-B family in the stomatogastric nervous system.

  9. Cautious application of pleural N-terminal pro-B-type natriuretic peptide in diagnosis of congestive heart failure pleural effusions among critically ill patients.

    Directory of Open Access Journals (Sweden)

    Jiann-Horng Yeh

    Full Text Available Several studies on diagnostic accuracy of pleural N-terminal pro-B-type natriuretic peptide (NT-pro-BNP for effusions from congestive heart failure (CHF conclude that pleural NT-pro-BNP is a useful biomarker with high diagnostic accuracy for distinguishing CHF effusions. However, its applicability in critical care settings remains uncertain and requires further investigations.NT-proBNP was measured in pleural fluid samples of a prospective cohort of intensive care unit patients with pleural effusions. Receiver operating characteristic curve analysis was performed to determine diagnostic accuracy of pleural NT-proBNP for prediction of CHF effusions.One hundred forty-seven critically ill patients were evaluated, 38 (26% with CHF effusions and 109 (74% with non-CHF effusions of various causes. Pleural NT-proBNP levels were significantly elevated in patients with CHF effusions. Pleural NT-pro-BNP demonstrated the area under the curve of 0.87 for diagnosing effusions due to CHF. With a cutoff of 2200 pg/mL, pleural NT-proBNP displayed high sensitivity (89% but moderate specificity (73%. Notably, 29 (27% of 109 patients with non-CHF effusions had pleural NT-proBNP levels >2200 pg/mL and these patients were more likely to experience septic shock (18/29 vs. 10/80, P<0.001 or acute kidney injury (19/29 vs. 9/80, P<0.001.Among critically ill patients, pleural NT-proBNP measurements remain a useful diagnostic aid in evaluation of pleural effusions. However, patients with non-CHF effusions may exhibit high pleural NT-proBNP concentrations if they suffer from septic shock or acute kidney injury. Accordingly, it is suggested that clinical context should be taken into account when interpreting pleural NT-proBNP values in critical care settings.

  10. The IACOB project . III. New observational clues to understand macroturbulent broadening in massive O- and B-type stars

    Science.gov (United States)

    Simón-Díaz, S.; Godart, M.; Castro, N.; Herrero, A.; Aerts, C.; Puls, J.; Telting, J.; Grassitelli, L.

    2017-01-01

    Context. The term macroturbulent broadening is commonly used to refer to a certain type of non-rotational broadening affecting the spectral line profiles of O- and B-type stars. It has been proposed to be a spectroscopic signature of the presence of stellar oscillations; however, we still lack a definitive confirmation of this hypothesis. Aims: We aim to provide new empirical clues about macroturbulent spectral line broadening in O- and B-type stars to evaluate its physical origin. Methods: We used high-resolution spectra of 430 stars with spectral types in the range O4 - B9 (all luminosity classes) compiled in the framework of the IACOB project. We characterized the line broadening of adequate diagnostic metal lines using a combined Fourier transform and goodness-of-fit technique. We performed a quantitative spectroscopic analysis of the whole sample using automatic tools coupled with a huge grid of fastwind models to determine their effective temperatures and gravities. We also incorporated quantitative information about line asymmetries into our observational description of the characteristics of the line profiles, and performed a comparison of the shape and type of line-profile variability found in a small sample of O stars and B supergiants with still undefined pulsational properties and B main-sequence stars with variable line profiles owing to a well-identified type of stellar oscillations or to the presence of spots in the stellar surface. Results: We present a homogeneous and statistically significant overview of the (single snapshot) line-broadening properties of stars in the whole O and B star domain. We find empirical evidence of the existence of various types of non-rotational broadening agents acting in the realm of massive stars. Even though all these additional sources of line-broadening could be quoted and quantified as a macroturbulent broadening from a practical point of view, their physical origin can be different. Contrarily to the early- to

  11. The prognostic value of N-terminal proB-type natriuretic peptide in patients with acute respiratory distress syndrome

    Science.gov (United States)

    Lai, Chih-Cheng; Sung, Mei-I.; Ho, Chung-Han; Liu, Hsiao-Hua; Chen, Chin-Ming; Chiang, Shyh-Ren; Chao, Chien-Ming; Liu, Wei-Lun; Hsing, Shu-Chen; Cheng, Kuo-Chen

    2017-01-01

    We investigated whether N-terminal proB-type natriuretic peptide (NT-proBNP) predicts the prognosis of patients with acute respiratory distress syndrome (ARDS). Between December 1, 2012, and May 31, 2015, this observational study recruited patients admitted to our tertiary medical center who met the Berlin criteria for ARDS and who had their NT-proBNP measured. The main outcome was 28-day mortality. We enrolled 61 patients who met the Berlin criteria for ARDS: 7 were classified as mild, 29 as moderate, and 25 as severe. The median APACHE II scores were 23 (interquartile range [IQR], 18–28), and SOFA scores were 11 (IQR, 8–13). The median lung injury score was 3.0 (IQR, 2.50–3.25), and the median level of NT-proBNP was 2011 pg/ml (IQR, 579–7216). Thirty-four patients died during this study, and the 28-day mortality rate was 55.7%. Patients who die were older and had significantly (all p < 0.05) higher APACHE II scores and NT-proBNP levels than did patients who survived. Multivariate analysis identified age (HR: 1.546, 95% CI: 1.174–2.035, p = 0.0019) and NT-proBNP (HR: 1.009, 95% CI: 1.004–1.013, p = 0.0001) as significant risk factors of death. NT-proBNP was associated with poor outcomes for patients with ARDS, and its level predicted mortality. PMID:28322314

  12. The evaluation of B-type Natriuretic Peptide and Troponin I in acute myocardial infarction and unstable angina

    Directory of Open Access Journals (Sweden)

    Nafija Serdarevic

    2014-09-01

    Full Text Available Introduction: The diagnostic utility of B-type natriuretic peptide (BNP has prompted interest in its use as an aid in the detection of early heart failure and assessment of diseases. The first objective of this study was measurement of BNP and troponin I (TnI blood levels in patients with acute myocardial infarction (AMI and unstable angina. The second objective of this study was to find a correlation between TnI and BNP in blood.Methods: The concentrations of BNP and TnI in 150 blood levels were determined using CMIA (chemiluminescent microparticle immunoassay Architect and 2000 (Abbott diagnostics. The retrospective study included 100 patients who were hospitalized at the Department of Internal Medicine of the University Clinical Center Sarajevo and 50 healthy control. The reference blood range of BNP is 0-100 pg/mL and TnI is 0.00-0.4 ng/mL.Results: In the patients with AMI the mean value of BNP is 764.48 ± 639.52 pg/mL and TnI is 2.50 ± 2.28ng/mL. The patients with unstable angina have BNP 287.18 ± 593.20 pg/mL and TnI 0.10 ± 0.23 ng/mL. Our studies have shown that the correlation between BNP and TnI was statistically significant for p< 0.05 using Student t test with correlation coefficient r = 0.36. Conclusions: BNP and TnI levels can help to identify the patients with a high risk for cardiovascular diseases.

  13. Evaluation of B-type Natriuretic Peptide for validation of a heart failure register in primary care

    Directory of Open Access Journals (Sweden)

    Hughes Elizabeth A

    2007-07-01

    Full Text Available Abstract Background Diagnosing heart failure and left ventricular systolic dysfunction is difficult on clinical grounds alone. We sought to determine the accuracy of a heart failure register in a single primary care practice, and to examine the usefulness of b-type (or brain natriuretic peptide (BNP assay for this purpose. Methods A register validation audit in a single general practice in the UK was carried out. Of 217 patients on the heart failure register, 56 of 61 patients who had not been previously investigated underwent 12-lead electrocardiography and echocardiography within the practice site. Plasma was obtained for BNP assay from 45 subjects, and its performance in identifying echocardiographic abnormalities consistent with heart failure was assessed by analysing area under receiver operator characteristic (ROC curves. Results 30/217 were found to have no evidence to suggest heart failure on notes review and were probably incorrectly coded. 70/112 who were previously investigated were confirmed to have heart failure. Of those not previously investigated, 24/56 (42.9% who attended for the study had echocardiographic left ventricular systolic dysfunction. A further 8 (14.3% had normal systolic function, but had left ventricular hypertrophy or significant valve disease. Overall, echocardiographic features consistent with heart failure were found in only 102/203 (50.2%. BNP was poor at discriminating those with and without systolic dysfunction (area under ROC curve 0.612, and those with and without any significant echocardiographic abnormality (area under ROC curve 0.723. Conclusion In this practice, half of the registered patients did not have significant cardiac dysfunction. On-site echocardiography identifies patients who can be removed from the heart failure register. The use of BNP assay to determine which patients require echocardiography is not supported by these data.

  14. CDK-1 and two B-type cyclins promote PAR-6 stabilization during polarization of the early C. elegans embryo.

    Directory of Open Access Journals (Sweden)

    Alexia Rabilotta

    Full Text Available In the C. elegans embryo, formation of an antero-posterior axis of polarity relies on signaling by the conserved PAR proteins, which localize asymmetrically in two mutually exclusive groups at the embryonic cortex. Depletion of any PAR protein causes a loss of polarity and embryonic lethality. A genome-wide RNAi screen previously identified two B-type cyclins, cyb-2.1 and cyb-2.2, as suppressors of par-2(it5ts lethality. We found that the loss of cyb-2.1 or cyb-2.2 suppressed the lethality and polarity defects of par-2(it5ts mutants and that these cyclins act in cell polarity with their cyclin-dependent kinase partner, CDK-1. Interestingly, cyb-2.1; cyb-2.2 double mutants did not show defects in cell cycle progression or timing of polarity establishment, suggesting that they regulate polarity independently of their typical role in cell cycle progression. Loss of both cyclin genes or of cdk-1 resulted in a decrease in PAR-6 levels in the embryo. Furthermore, the activity of the cullin CUL-2 was required to achieve suppression of par-2 lethality when both cyclins were absent. Our results support a model in which CYB-2.1/2/CDK-1 antagonize CUL-2 activity to promote stabilization of PAR-6 levels during polarization of the early C. elegans embryo. They also suggest that CYB-2.1 and CYB-2.2 contribute to the coupling of cell cycle progression and asymmetric segregation of cell fate determinants.

  15. Oxygen abundance determination of B-type stars with the O I 7771-5 Å lines*

    Science.gov (United States)

    Takeda, Yoichi; Honda, Satoshi

    2016-06-01

    Oxygen abundances of 34 B-type stars in the effective temperature range of Teff ˜ 10000-28000 K with diversified rotational velocities (vesin i ˜ 0-250 km s-1) were determined from the O I triplet lines at 7771-5 Å, with an aim of examining whether this O I feature can be a reliable abundance indicator for such high-temperature stars including rapid rotators. It revealed that the required non-local thermodynamic equilibrium (LTE) abundance correction is distinctly large (ranging from ˜-0.6 dex to ˜-1.7 dex) and its consideration is indispensable. On the condition that the non-LTE effect is taken into account, this triplet is a useful O abundance indicator (with a precision of ≲ 0.2 dex) up to Teff ≲ 25000 K, since its total equivalent width is sufficiently large ( ≳ 200 mÅ). In contrast, it is not adequate for abundance derivation for stars at Teff ≳ 25000 K, where its strength rapidly drops down toward a hardly detectable level (except for sharp-lined stars) and its sensitivity to Teff or log g becomes considerably large. The resulting non-LTE oxygen abundances turned out to be almost normal (i.e., near-solar around ˜8.7-8.8 within ˜±0.2 dex) for most stars without any dependence upon projected rotational velocity as well as luminosity (or mass), which is consistent with the prediction of recent stellar evolution calculations.

  16. Predictors of Left Ventricle Remodeling: Combined Plasma B-type Natriuretic Peptide Decreasing Ratio and Peak Creatine Kinase-MB.

    Science.gov (United States)

    Hsu, Jen-Te; Chung, Chang-Min; Chu, Chi-Ming; Lin, Yu-Shen; Pan, Kuo-Li; Chang, Jung-Jung; Wang, Po-Chang; Chang, Shih-Tai; Yang, Teng-Yao; Jang, Shih-Jung; Yang, Tsung-Han; Hsiao, Ju-Feng

    2017-01-01

    Background: Previous studies reported that patients who had an acute myocardial infarction (AMI) have found that measuring B-type natriuretic peptide (BNP) during the subacute phase of left ventricular (LV) remodeling can predict the possible course of LV remodeling. This study assessed the use of serial BNP serum levels combined with early creatine kinase-MB (CK-MB) to predict the development of significant LV remodeling in AMI patients. Methods: Nighty-seven patients with new onset AMI were assessed using serial echocardiographic studies and serial measurements of BNP levels, both performed on day-2 (BNP1), day-7 (BNP2), day-90 (BNP3), and day-180 (BNP4) after admission. LV remodeling was defined as >20% increase in biplane LV end-diastolic volume on day-180 compared to baseline (day-2). Results: Patients were divided into LV remodeling [LVR(+)] and non LV remodeling [LVR(-)] groups. No first-week BNP level was found to predict remodeling. However, the two groups had significantly different day-90 BNP level (208.1 ± 263.7 pg/ml vs. 82.4 ± 153.7 pg/ml, P = 0.039) and significantly different 3-month BNP decrease ratios ( R BNP13) (14.4 ± 92.2% vs. 69.4 ± 25.9%, P remodeling. Additionally, combining peak CK-MB and R BNP13 offered an excellent discrimination for half-year remodeling when assessed by ROC curve (AUC = 0.818, P remodeling. The early peak CK-MB additionally offered an incremental power to the predictions derived from serial BNP examinations.

  17. NLTE carbon abundance determination in selected A- and B-type stars and the interpretation of C I emission lines

    Science.gov (United States)

    Alexeeva, S. A.; Ryabchikova, T. A.; Mashonkina, L. I.

    2016-10-01

    We constructed a comprehensive model atom for C I-C II using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for C I and C II in classical 1D models representing the atmospheres of A- and late B-type stars. Our NLTE calculations predict the emission that appears at effective temperature of 9250 to 10 500 K depending on log g in the C I 8335, 9405 Å singlet lines and at Teff> 15 000 K (log g = 4) in the C I 9061-9111 Å, 9603-9658 Å triplet lines. A pre-requisite of the emission phenomenon is the overionization-recombination mechanism resulting in a depopulation of the lower levels of C I to a greater extent than the upper levels. Extra depopulation of the lower levels of the transitions corresponding to the near-infrared lines, is caused by photon loss in the UV lines C I 2479, 1930, and 1657 Å. We analysed the lines of C I and C II in Vega, HD 73666, Sirius, 21 Peg, π Cet, HD 22136, and ι Her taking advantage of their observed high-resolution spectra. The C I emission lines were detected in the four hottest stars, and they were well reproduced in our NLTE calculations. For each star, the mean NLTE abundances from lines of the two ionization stages, C I and C II, including the C I emission lines, were found to be consistent. We show that the predicted C I emission phenomenon depends strongly on whether accurate or approximate electron-impact excitation rates are applied.

  18. Caspase cleavage of cytochrome c1 disrupts mitochondrial function and enhances cytochrome c release

    Institute of Scientific and Technical Information of China (English)

    Yushan Zhu; Min Li; Xiaohui Wang; Haijing Jin; Shusen Liu; Jianxin Xu; Quan Chen

    2012-01-01

    Mitochondrial catastrophe can be the cause or consequence of apoptosis and is associated with a number of pathophysiological conditions.The exact relationship between mitochondrial catastrophe and caspase activation is not completely understood.Here we addressed the underlying mechanism,explaining how activated caspase could feedback to attack mitochondria to amplify further cytochrome e (cyto.c) release.We discovered that cytochrome c1 (cyto.c1) in the bc1 complex of the mitochondrial respiration chain was a novel substrate of caspase 3 (casp.3).We found that cyto.c1 was cleaved at the site of D106,which is critical for binding with cyto.c,following apoptotic stresses or targeted expression of casp.3 into tbe mitochondrial intermembrane space.We demonstrated that this cleavage was closely linked with further cyto.c release and mitochondrial catastrophe.These mitochondrial events could be effectively blocked by expressing non-cleavable cyto.c1 (D106A) or by caspase inhibitor z-VAD-fmk.Our results demonstrate that the cleavage of cyto.c1 represents a critical step for the feedback amplification of cyto.c release by caspases and subsequent mitochondrial catastrophe.

  19. The planetary biology of cytochrome P450 aromatases

    Directory of Open Access Journals (Sweden)

    Gaucher Eric A

    2004-08-01

    Full Text Available Abstract Background Joining a model for the molecular evolution of a protein family to the paleontological and geological records (geobiology, and then to the chemical structures of substrates, products, and protein folds, is emerging as a broad strategy for generating hypotheses concerning function in a post-genomic world. This strategy expands systems biology to a planetary context, necessary for a notion of fitness to underlie (as it must any discussion of function within a biomolecular system. Results Here, we report an example of such an expansion, where tools from planetary biology were used to analyze three genes from the pig Sus scrofa that encode cytochrome P450 aromatases–enzymes that convert androgens into estrogens. The evolutionary history of the vertebrate aromatase gene family was reconstructed. Transition redundant exchange silent substitution metrics were used to interpolate dates for the divergence of family members, the paleontological record was consulted to identify changes in physiology that correlated in time with the change in molecular behavior, and new aromatase sequences from peccary were obtained. Metrics that detect changing function in proteins were then applied, including KA/KS values and those that exploit structural biology. These identified specific amino acid replacements that were associated with changing substrate and product specificity during the time of presumed adaptive change. The combined analysis suggests that aromatase paralogs arose in pigs as a result of selection for Suoidea with larger litters than their ancestors, and permitted the Suoidea to survive the global climatic trauma that began in the Eocene. Conclusions This combination of bioinformatics analysis, molecular evolution, paleontology, cladistics, global climatology, structural biology, and organic chemistry serves as a paradigm in planetary biology. As the geological, paleontological, and genomic records improve, this approach should

  20. Cytochrome P450 gene polymorphism and cancer.

    Science.gov (United States)

    Agundez, Jose A G

    2004-06-01

    Human cytochrome P450 (CYP) enzymes play a key role in the metabolism of drugs and environmental chemicals. Several CYP enzymes metabolically activate procarcinogens to genotoxic intermediates. Phenotyping analyses revealed an association between CYP enzyme activity and the risk to develop several forms of cancer. Research carried out in the last decade demonstrated that several CYP enzymes are polymorphic due to single nucleotide polymorphisms, gene duplications and deletions. As genotyping procedures became available for most human CYP, an impressive number of association studies on CYP polymorphisms and cancer risk were conducted. Here we review the findings obtained in these studies regarding CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A4, CYP3A5, CYP3A7, CYP8A1 and CYP21 gene polymorphisms. Consistent evidences for association between CYP polymorphisms and lung, head and neck, and liver cancer were reported. Controversial findings suggest that colorectal and prostate cancers may be associated to CYP polymorphisms, whereas no evidences for a relevant association with breast or bladder cancers were reported. We summarize the available information related to the association of CYP polymorphisms with leukaemia, lymphomas and diverse types of cancer that were investigated only for some CYP genes, including brain, esophagus, stomach, pancreas, pituitary, cervical epithelium, melanoma, ovarian, kidney, anal and vulvar cancers. This review discusses on causes of heterogeneity in the proposed associations, controversial findings on cancer risk, and identifies topics that require further investigation. In addition, some recommendations on study design, in order to obtain more conclusive findings in further studies, are provided.

  1. Cytochromes P450 and insecticide resistance.

    Science.gov (United States)

    Scott, J G

    1999-09-01

    The cytochrome P450-dependent monooxygenases (monooxygenases) are an extremely important metabolic system involved in the catabolism and anabolism of xenobiotics and endogenous compounds. Monooxygenase-mediated metabolism is a common mechanism by which insects become resistant to insecticides as evidenced by the numerous insect species and insecticides affected. This review begins by presenting background information about P450s, the role of monooxygenases in insects, and the different techniques that have been used to isolate individual insect P450s. Next, insecticide resistance is briefly described, and then historical information about monooxygenase-mediated insecticide resistance is reviewed. For any case of monooxygenase-mediated resistance, identification of the P450(s) involved, out of the dozens that are present in an insect, has proven very challenging. Therefore, the next section of the review focuses on the minimal criteria for establishing that a P450 is involved in resistance. This is followed by a comprehensive examination of the literature concerning the individual P450s that have been isolated from insecticide resistant strains. In each case, the history of the strain and the evidence for monooxygenase-mediated resistance are reviewed. The isolation and characterization of the P450(s) from the strain are then described, and the evidence of whether or not the isolated P450(s) is involved in resistance is summarized. The remainder of the review summarizes our current knowledge of the molecular basis of monooxygenase-mediated resistance and the implications for the future. The importance of these studies for development of effective insecticide resistance management strategies is discussed.

  2. B-type natriuretic peptide and C-reactive protein in the prediction of atrial fibrillation risk: the CHARGE-AF Consortium of community-based cohort studies

    NARCIS (Netherlands)

    M.F. Sinner (Moritz); K.A. Stepas (Katherine A.); C.B. Moser (Carlee B.); B.P. Krijthe (Bouwe); T. Aspelund (Thor); N. Sotoodehnia (Nona); M. Fontes (Michel); A.C.J.W. Janssens (Cécile); R.A. Kronmal (Richard); J.W. Magnani (Jared); J.C.M. Witteman (Jacqueline); A.M. Chamberlain (Alanna); S.A. Lubitz (Steven); R. Schnabel (Renate); R.S. Vasan (Ramachandran S.); T.J. Wang (Thomas); S.K. Agarwal (Sunil); D.D. McManus (David); O.H. Franco (Oscar); X. Yin (Xiaoyan); M.G. Larson (Martin); G.L. Burke (Greg); L.J. Launer (Lenore); A. Hofman (Albert); D. Levy (Daniel); J.S. Gottdiener (John); S. Kääb (Stefan); D.J. Couper (David); T.B. Harris (Tamara); B.C. Astor (Brad); C. Ballantyne (Christie); R.C. Hoogeveen (Ron); T. Arai (Takashi); E.Z. Soliman (Elsayed Z.); P.T. Ellinor (Patrick); B.H.Ch. Stricker (Bruno); V. Gudnason (Vilmundur); S.R. Heckbert (Susan); M. Pencina (Michael); E.J. Benjamin (Emelia); A. Alonso (Alvaro)

    2014-01-01

    textabstractAIMS: B-type natriuretic peptide (BNP) and C-reactive protein (CRP) predict atrial fibrillation (AF) risk. However, their risk stratification abilities in the broad community remain uncertain. We sought to improve risk stratification for AF using biomarker information.METHODS AND RESULTS

  3. Increased B-type natriuretic peptide and decreased proteinuria might reflect decreased capillary leakage and is associated with a better outcome in patients with severe burns

    NARCIS (Netherlands)

    de Leeuw, Karina; Nieuwenhuis, Marianne K; Niemeijer, Anuschka S; Eshuis, Hans; Beerthuizen, Gerard I J M; Janssen, Wilbert M

    2011-01-01

    INTRODUCTION: It is difficult to adjust fluid balance adequately in patients with severe burns due to various physical changes. B-type natriuretic peptide (BNP) is emerging as a potential marker of hydration state. Proteinuria is used as a predictor of outcome in severe illness and might correlate t

  4. Molecular cloning and characterization of a Perilla frutescens cytochrome P450 enzyme that catalyzes the later steps of perillaldehyde biosynthesis.

    Science.gov (United States)

    Fujiwara, Yumi; Ito, Michiho

    2017-02-01

    Perilla produces the cyclohexanoid monoterpene perillaldehyde as a major constituent of an essential oil that is accumulated in its glandular trichomes. Perillaldehyde is a marker compound for quality control of soyo and has biological activities such as antibacterial, sedative, or vasodilatory effects. The predicted perillaldehyde formation involves the cyclization of geranyl diphosphate, hydroxylation, and oxidation, and cytochrome P450 plays a crucial role in perillaldehyde biosynthesis. In this study, a cytochrome P450-type enzyme with perillyl alcohol and perillaldehyde synthase activities was isolated by analyzing an expressed sequence tag library from several oil types of pure lines of perilla. A recombinant protein with a sequence that was highly specific for the type of perillaldehyde was expressed in Saccharomyces cerevisiae and evaluated by an in vitro enzymatic reaction. The recombinant protein catalyzed the hydroxylation and oxidation of limonene to perillyl alcohol and perillaldehyde. Cytochrome P450 limonene-7-hydroxylase cDNA from Perilla frutescens has been previously isolated. The cytochrome P450 isolated in this study shares 37% amino-acid identity with the previously isolated enzyme; however, it may have different characteristics.

  5. TOF-SIMS structural characterization of self-assembly monolayer of cytochrome b5 onto gold substrate

    CERN Document Server

    Aoyagi, Satoka; Boireau, Wilfrid; 10.1016/j.apsusc.2008.05.086

    2010-01-01

    Orientation and three-dimensional structure of immobilized proteins on bio-devices are very important to assure their high performance. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is able to analyze upper surface of one layer of molecules. Orientation of immobilized proteins can be evaluated based on determination of a partial structure, representing ensemble of amino acids, on the surface part. In this study, a monolayer of cytochrome b5 was reconstituted onto gold substrate and investigated by surface plasmon resonance (SPR). After freeze-drying, the resulted protein self-assembly was evaluated using TOF-SIMS with the bismuth cluster ion source, and then TOF-SIMS spectra were analyzed to select peaks specific to cytochrome b5 and identify their chemical formula and ensembles of amino acids. The results from TOF-SIMS spectra analysis were compared to the amino acid sequence of the modified cytochrome b5 and three-dimensional structure of cytochrome b5 registered in the protein data bank. Finall...

  6. B-type natriuretic peptide and C-reactive protein in the prediction of atrial fibrillation risk: the CHARGE-AF Consortium of community-based cohort studies

    Science.gov (United States)

    Sinner, Moritz F.; Stepas, Katherine A.; Moser, Carlee B.; Krijthe, Bouwe P.; Aspelund, Thor; Sotoodehnia, Nona; Fontes, João D.; Janssens, A. Cecile J.W.; Kronmal, Richard A.; Magnani, Jared W.; Witteman, Jacqueline C.; Chamberlain, Alanna M.; Lubitz, Steven A.; Schnabel, Renate B.; Vasan, Ramachandran S.; Wang, Thomas J.; Agarwal, Sunil K.; McManus, David D.; Franco, Oscar H.; Yin, Xiaoyan; Larson, Martin G.; Burke, Gregory L.; Launer, Lenore J.; Hofman, Albert; Levy, Daniel; Gottdiener, John S.; Kääb, Stefan; Couper, David; Harris, Tamara B.; Astor, Brad C.; Ballantyne, Christie M.; Hoogeveen, Ron C.; Arai, Andrew E.; Soliman, Elsayed Z.; Ellinor, Patrick T.; Stricker, Bruno H.C.; Gudnason, Vilmundur; Heckbert, Susan R.; Pencina, Michael J.; Benjamin, Emelia J.; Alonso, Alvaro

    2014-01-01

    Aims B-type natriuretic peptide (BNP) and C-reactive protein (CRP) predict atrial fibrillation (AF) risk. However, their risk stratification abilities in the broad community remain uncertain. We sought to improve risk stratification for AF using biomarker information. Methods and results We ascertained AF incidence in 18 556 Whites and African Americans from the Atherosclerosis Risk in Communities Study (ARIC, n=10 675), Cardiovascular Health Study (CHS, n = 5043), and Framingham Heart Study (FHS, n = 2838), followed for 5 years (prediction horizon). We added BNP (ARIC/CHS: N-terminal pro-B-type natriuretic peptide; FHS: BNP), CRP, or both to a previously reported AF risk score, and assessed model calibration and predictive ability [C-statistic, integrated discrimination improvement (IDI), and net reclassification improvement (NRI)]. We replicated models in two independent European cohorts: Age, Gene/Environment Susceptibility Reykjavik Study (AGES), n = 4467; Rotterdam Study (RS), n = 3203. B-type natriuretic peptide and CRP were significantly associated with AF incidence (n = 1186): hazard ratio per 1-SD ln-transformed biomarker 1.66 [95% confidence interval (CI), 1.56–1.76], P < 0.0001 and 1.18 (95% CI, 1.11–1.25), P < 0.0001, respectively. Model calibration was sufficient (BNP, χ2 = 17.0; CRP, χ2 = 10.5; BNP and CRP, χ2 = 13.1). B-type natriuretic peptide improved the C-statistic from 0.765 to 0.790, yielded an IDI of 0.027 (95% CI, 0.022–0.032), a relative IDI of 41.5%, and a continuous NRI of 0.389 (95% CI, 0.322–0.455). The predictive ability of CRP was limited (C-statistic increment 0.003). B-type natriuretic peptide consistently improved prediction in AGES and RS. Conclusion B-type natriuretic peptide, not CRP, substantially improved AF risk prediction beyond clinical factors in an independently replicated, heterogeneous population. B-type natriuretic peptide may serve as a benchmark to evaluate novel putative AF risk biomarkers. PMID:25037055

  7. Identification of five B-type response regulators as members of a multistep phosphorelay system interacting with histidine-containing phosphotransfer partners of Populus osmosensor

    Directory of Open Access Journals (Sweden)

    Bertheau Lucie

    2012-12-01

    Full Text Available Abstract Background In plants, the multistep phosphorelay signaling pathway mediates responses to environmental factors and plant hormones. This system is composed of three successive partners: hybrid Histidine-aspartate Kinases (HKs, Histidine-containing Phosphotransfer proteins (HPts, and Response Regulators (RRs. Among the third partners, B-type RR family members are the final output elements of the pathway; they act as transcription factors and clearly play a pivotal role in the early response to cytokinin in Arabidopsis. While interactions studies between partners belonging to the multistep phosphorelay system are mainly focused on protagonists involved in cytokinin or ethylene pathways, very few reports are available concerning partners of osmotic stress signaling pathway. Results In Populus, we identified eight B-type RR proteins, RR12-16, 19, 21 and 22 in the Dorskamp genotype. To assess HPt/B-type RR interactions and consequently determine potential third partners in the osmosensing multistep phosphorelay system, we performed global yeast two-hybrid (Y2H assays in combination with Bimolecular Fluorescence Complementation (BiFC assays in plant cells. We found that all B-type RRs are able to interact with HPt predominant partners (HPt2, 7 and 9 of HK1, which is putatively involved in the osmosensing pathway. However, different profiles of interaction are observed depending on the studied HPt. HPt/RR interactions displayed a nuclear localization, while the nuclear and cytosolic localization of HPt and nuclear localization of RR proteins were validated. Although the nuclear localization of HPt/RR interaction was expected, this work constitutes the first evidence of such an interaction in plants. Furthermore, the pertinence of this partnership is reinforced by highlighting a co-expression of B-type RR transcripts and the other partners (HK1 and HPts belonging to a potential osmosensing pathway. Conclusion Based on the interaction studies

  8. Comparative studies of vertebrate scavenger receptor class B type 1: a high-density lipoprotein binding protein

    Directory of Open Access Journals (Sweden)

    Holmes RS

    2012-06-01

    Full Text Available Roger S Holmes,1,2 Laura A Cox11Department of Genetics and Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA; 2School of Biomolecular and Physical Sciences, Griffith University, Nathan, Queensland, AustraliaAbstract: Scavenger receptor class B type 1 protein (SCARB1 plays an essential role in cholesterol homeostasis and functions in binding high density lipoprotein cholesterol (HDL in liver and other tissues of the body. SCARB1 also functions in lymphocyte homeostasis and in the uptake of hepatitis C virus (HCV by the liver. A genetic deficiency of this protein results in autoimmune disorders and significant changes in blood cholesterol phenotype. Comparative SCARB1 amino acid sequences and structures and SCARB1 gene locations were examined using data from several vertebrate genome projects. Vertebrate SCARB1 sequences shared 50%–99% identity as compared with 28%–31% sequence identities with other CD36-like superfamily members, ie, SCARB2 and SCARB3 (also called CD36. At least eight N-glycosylation sites were conserved among most of the vertebrate SCARB1 proteins examined. Sequence alignments, key amino acid residues, and conserved predicted secondary structures were also studied, including: cytoplasmic, transmembrane, and exoplasmic sequences; conserved N-terminal and C-terminal transmembrane glycines which participate in oligomer formation; conserved cystine disulfides and a free SH residue which participates in lipid transport; carboxyl terminal PDZ-binding domain sequences (Ala507-Arg/Lys508-Leu509; and 30 conserved proline and 18 conserved glycine residues, which may contribute to short loop formation within the exoplasmic HDL-binding sequence. Vertebrate SCARB1 genes usually contained 12 coding exons. The human SCARB1 gene contained CpG islands, micro RNA binding sites, and several transcription factor binding sites (including PPARG which may contribute to the high level (13.7 times

  9. Mendelian randomization study of B-type natriuretic peptide and type 2 diabetes: evidence of causal association from population studies.

    Directory of Open Access Journals (Sweden)

    Roman Pfister

    2011-10-01

    Full Text Available BACKGROUND: Genetic and epidemiological evidence suggests an inverse association between B-type natriuretic peptide (BNP levels in blood and risk of type 2 diabetes (T2D, but the prospective association of BNP with T2D is uncertain, and it is unclear whether the association is confounded. METHODS AND FINDINGS: We analysed the association between levels of the N-terminal fragment of pro-BNP (NT-pro-BNP in blood and risk of incident T2D in a prospective case-cohort study and genotyped the variant rs198389 within the BNP locus in three T2D case-control studies. We combined our results with existing data in a meta-analysis of 11 case-control studies. Using a Mendelian randomization approach, we compared the observed association between rs198389 and T2D to that expected from the NT-pro-BNP level to T2D association and the NT-pro-BNP difference per C allele of rs198389. In participants of our case-cohort study who were free of T2D and cardiovascular disease at baseline, we observed a 21% (95% CI 3%-36% decreased risk of incident T2D per one standard deviation (SD higher log-transformed NT-pro-BNP levels in analysis adjusted for age, sex, body mass index, systolic blood pressure, smoking, family history of T2D, history of hypertension, and levels of triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol. The association between rs198389 and T2D observed in case-control studies (odds ratio = 0.94 per C allele, 95% CI 0.91-0.97 was similar to that expected (0.96, 0.93-0.98 based on the pooled estimate for the log-NT-pro-BNP level to T2D association derived from a meta-analysis of our study and published data (hazard ratio = 0.82 per SD, 0.74-0.90 and the difference in NT-pro-BNP levels (0.22 SD, 0.15-0.29 per C allele of rs198389. No significant associations were observed between the rs198389 genotype and potential confounders. CONCLUSIONS: Our results provide evidence for a potential causal role of the BNP

  10. Predictors of Left Ventricle Remodeling: Combined Plasma B-type Natriuretic Peptide Decreasing Ratio and Peak Creatine Kinase-MB

    Science.gov (United States)

    Hsu, Jen-Te; Chung, Chang-Min; Chu, Chi-Ming; Lin, Yu-Shen; Pan, Kuo-Li; Chang, Jung-Jung; Wang, Po-Chang; Chang, Shih-Tai; Yang, Teng-Yao; Jang, Shih-Jung; Yang, Tsung-Han; Hsiao, Ju-Feng

    2017-01-01

    Background: Previous studies reported that patients who had an acute myocardial infarction (AMI) have found that measuring B-type natriuretic peptide (BNP) during the subacute phase of left ventricular (LV) remodeling can predict the possible course of LV remodeling. This study assessed the use of serial BNP serum levels combined with early creatine kinase-MB (CK-MB) to predict the development of significant LV remodeling in AMI patients. Methods: Nighty-seven patients with new onset AMI were assessed using serial echocardiographic studies and serial measurements of BNP levels, both performed on day-2 (BNP1), day-7 (BNP2), day-90 (BNP3), and day-180 (BNP4) after admission. LV remodeling was defined as >20% increase in biplane LV end-diastolic volume on day-180 compared to baseline (day-2). Results: Patients were divided into LV remodeling [LVR(+)] and non LV remodeling [LVR(-)] groups. No first-week BNP level was found to predict remodeling. However, the two groups had significantly different day-90 BNP level (208.1 ± 263.7 pg/ml vs. 82.4 ± 153.7 pg/ml, P = 0.039) and significantly different 3-month BNP decrease ratios (RBNP13) (14.4 ± 92.2% vs. 69.4 ± 25.9%, P < 0.001). The appropriate cut-off value for RBNP13 was 53.2% (AUC = 0.764, P < 0.001). Early peak CK-MB (cut-off 48.2 ng/ml; AUC = 0.672; P = 0.014) was another independent predictor of remodeling. Additionally, combining peak CK-MB and RBNP13 offered an excellent discrimination for half-year remodeling when assessed by ROC curve (AUC = 0.818, P < 0.001). Conclusion: RBNP13 is a significant independent predictor of 6-month LV remodeling. The early peak CK-MB additionally offered an incremental power to the predictions derived from serial BNP examinations. PMID:28138312

  11. Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte.

    Science.gov (United States)

    Reboul, Emmanuelle; Klein, Alexis; Bietrix, Florence; Gleize, Béatrice; Malezet-Desmoulins, Christiane; Schneider, Martina; Margotat, Alain; Lagrost, Laurent; Collet, Xavier; Borel, Patrick

    2006-02-24

    Although cellular uptake of vitamin E was initially described as a passive process, recent studies in the liver and brain have shown that SR-BI (scavenger receptor class B type I) is involved in this phenomenon. As SR-BI is expressed at high levels in the intestine, the present study addressed the involvement of SR-BI in vitamin E trafficking across enterocytes. Apical uptake and efflux of the main dietary forms of vitamin E were examined using Caco-2 TC-7 cell monolayers as a model of human intestinal epithelium. (R,R,R)-gamma-tocopherol bioavailability was compared between wild-type mice and mice overexpressing SR-BI in the intestine. The effect of vitamin E on enterocyte SR-BI mRNA levels was measured by real-time quantitative reverse transcription-PCR. Concentration-dependent curves for vitamin E uptake were similar for (R,R,R)-alpha-, (R,R,R)-gamma-, and dl-alpha-tocopherol. (R,R,R)-alpha-tocopherol transport was dependent on incubation temperature, with a 60% reduction in absorption at 4 degrees C compared with 37 degrees C (p < 0.05). Vitamin E flux in enterocytes was directed from the apical to the basal side, with a relative 10-fold reduction in the transfer process when measured in the opposite direction (p < 0.05). Co-incubation with cholesterol, gamma-tocopherol, or lutein significantly impaired alpha-tocopherol absorption. Anti-human SR-BI antibodies and BLT1 (a chemical inhibitor of lipid transport via SR-BI) blocked up to 80% of vitamin E uptake and up to 30% of apical vitamin E efflux (p < 0.05), and similar results were obtained for (R,R,R)-gamma-tocopherol. SR-BI mRNA levels were not significantly modified after a 24-h incubation of Caco-2 cells with vitamin E. Finally, (R,R,R)-gamma-tocopherol bioavailability was 2.7-fold higher in mice overexpressing SR-BI than in wild-type mice (p < 0.05). The present data show for the first time that vitamin E intestinal absorption is, at least in part, mediated by SR-BI.

  12. Essential histidine pairs indicate conserved haem binding in epsilonproteobacterial cytochrome c haem lyases.

    Science.gov (United States)

    Kern, Melanie; Scheithauer, Juliane; Kranz, Robert G; Simon, Jörg

    2010-12-01

    Bacterial cytochrome c maturation occurs at the outside of the cytoplasmic membrane, requires transport of haem b across the membrane, and depends on membrane-bound cytochrome c haem lyase (CCHL), an enzyme that catalyses covalent attachment of haem b to apocytochrome c. Epsilonproteobacteria such as Wolinella succinogenes use the cytochrome c biogenesis system II and contain unusually large CCHL proteins of about 900 amino acid residues that appear to be fusions of the CcsB and CcsA proteins found in other bacteria. CcsBA-type CCHLs have been proposed to act as haem transporters that contain two haem b coordination sites located at different sides of the membrane and formed by histidine pairs. W. succinogenes cells contain three CcsBA-type CCHL isoenzymes (NrfI, CcsA1 and CcsA2) that are known to differ in their specificity for apocytochromes and apparently recognize different haem c binding motifs such as CX(2)CH (by CcsA2), CX(2)CK (by NrfI) and CX(15)CH (by CcsA1). In this study, conserved histidine residues were individually replaced by alanine in each of the W. succinogenes CCHLs. Characterization of NrfI and CcsA1 variants in W. succinogenes demonstrated that a set of four histidines is essential for maturing the dedicated multihaem cytochromes c NrfA and MccA, respectively. The function of W. succinogenes CcsA2 variants produced in Escherichia coli was also found to depend on each of these four conserved histidine residues. The presence of imidazole in the growth medium of both W. succinogenes and E. coli rescued the cytochrome c biogenesis activity of most histidine variants, albeit to different extents, thereby implying the presence of two functionally distinct histidine pairs in each CCHL. The data support a model in which two conserved haem b binding sites are involved in haem transport catalysed by CcsBA-type CCHLs.

  13. Intrageneric phylogeny of Acomys (rodentia, muridae) using mitochondrial gene cytochrome b.

    Science.gov (United States)

    Barome, P O; Monnerot, M; Gautun, J C

    1998-06-01

    This paper investigates interspecies relationships within the genus Acomys (spiny mice) by analyzing entire mitochondrial cytochrome b gene (1141 bp). This gene provides strong phylogenetic signal, as shown by high support of the topology obtained (bootstrap value and RNA support number). The phylogeny is congruent with inferences from allozymes for the species considered. Controversial taxonomy of Acomys cahirinus, dimidiatus, airensis, and ignitus is clarified, with their specific ranks confirmed on the basis of tree topology and nucleotide distances. Phylogenetic relationship between the undescribed species Acomys sp. from west Africa and A. airensis argue in favor of two distinct colonization events in this zone.

  14. The Effects of Acute Hydrogen Sulfide Poisoning on Cytochrome P450 Isoforms Activity in Rats

    OpenAIRE

    Xianqin Wang; Mengchun Chen; Xinxin Chen; Jianshe Ma; Congcong Wen; Jianchun Pan; Lufeng Hu; Guanyang Lin

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe d...

  15. Pulse-radiolysis study of cytochrome c/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    van Leeuwen, W.; van Dijk, C.; Grande, H.J.; Veeger, C.

    1982-10-02

    Pulse-radiolysis experiments were performed in the presence of methyl viologen and cytochrome c/sub 3/. After the pulse, methyl viologen radicals are formed and the kinetics of these radicals with cytochrome c/sub 3/ are studied. The reaction between cytochrome c/sub 3/ and methyl viologen radicals (MV/sup +/) is diffusion controlled. The ionic strength dependence and the pH-dependence of this reaction were studied. From the ionic strength dependence (at pH 7.8) we found that the net charge of the fully oxidized cytochrome c/sub 3/ molecule was Z = +4.7 +- 0.7. After the pulse an equilibrium is reached for the reaction of MV/sup +/ with cytochrome c/sub 3/. From this equilibrium an apparent midpoint potential can be obtained. The apparent midpoint potential of this multihaem molecule was found to depend on the degree of reduction, ..cap alpha... With the help of the Nernst equation an empirical equation is obtained to describe this dependence of the midpoint potential: E/sub 0/ = -0.250-0.088 x (in V). An estimation is made of the energy of interaction between the haems due to electrostatic interactions (..delta..epsilon < 32 mV) and due to ionic strength effects (-12 mV < ..delta..epsilon < 26 mV). The results suggest that the redox properties of the individual haems in the cytochrome c/sub 3/ molecule are dependent on the degree of reduction of the other haems in the molecule. The reaction of cytochrome c/sub 3/ with MV/sup +/ or with ethanol radicals (EtOHsup(.)) has been compared with the reactions of horse-heart cytochrome c and of metmyoglobin with the same radicals. The reaction of MV/sup +/ or EtOHsup(.) with horse-heart cytochrome c is found to be diffusion controlled; the reactions with metmyoglobin on the other hand are most probably controlled by an activation energy.

  16. Proline-40 is Essential to Maintaining Cytochrome b5's Stability and Its Electron Transfer with Cytochrome c

    Institute of Scientific and Technical Information of China (English)

    WANG,Zhi-Qiang(王志强); WU,Jian(邬建); WANG,Yun-Hua(王韵华); QIAN,Wen(钱雯); XIE,Yi(谢毅); XIA,Zong-Xiang(夏宗芗); HUANG,Zhong-Xian(黄仲贤)

    2002-01-01

    In order to illustrate the roles played by Pro40 in the sturcture,properties and functions of Cytochrome b5, three mutated genes, P40V, P40Y, P40G were constructed in this work. Only the P40V gene was successfully expressed into holoprotein in E. coli JM83. According to the results of X-ray crystallographic analysis and various kinds of spectrostoscopy, it is evident that substituting valine for Pro40 does not result in significant alterations in the protein' soverall structure; however,local coformational perturbations in the proximity of the heme do occur. The redox potential of the P40V mutant is 40 mV lower than that of the wild type protein. Its stability towards heat, urea, acid and ethanol were significantly decreased. The mutation leads to a decrease in the hydrophobicity of the heme pocket, which is probably the major factor contributing to the above changes. Binding constants and electron transfer rates between cytochrome b5 and cytochrome c were determined using UV-visible spectroscopy and stopped-flow techniques for both the wild type and the mutant. The results showed that the substitution of Pro40 by valine does not influence the binding constant of cytochrome b5 to cytochrome c ; however, the electron transfer rate between them decreased significantly. This indicates that proline-40 is essential to maintaining cytochrome b5's stability and its electron transfer with cytochrome c.These studies also provided a good example that property and functional changes of a protein do not necessarily require large overall structural alterations; in most cases, only perturbations on the local conformations are suffcient to induce significant changes in protein′s properties and functions.

  17. Reduction of Heavy Metals by Cytochrome c(3)

    Energy Technology Data Exchange (ETDEWEB)

    ABDELOUAS,A.; GONG,W.L.; LUTZE,W.; NUTTALL,E.H.; SPRAGUE,F.; SHELNUTT,JOHN A.; STRIETELMEIER,B.A.; FRANCO,R.; MOURA,I.; MOURA,J.J.G.

    2000-01-18

    We report on reduction and precipitation of Se(VI), Pb(II), CU(II), U(VI), Mo(VI), and Cr(VI) in water by cytochrome c{sub 3} isolated from Desulfomicrobium baczdatum [strain 9974]. The tetraheme protein cytochrome c{sub 3} was reduced by sodium dithionite. Redox reactions were monitored by UV-visible spectroscopy of cytochrome c{sub 3}. Analytical electron microscopy work showed that Se(VI), Pb(II), and CU(II) were reduced to the metallic state, U(W) and Mo(W) to U(IV) and Mo(IV), respectively, and Cr(VI) probably to Cr(III). U(IV) and Mo(W) precipitated as oxides and Cr(III) as an amorphous hydroxide. Cytochrome c{sub 3} was used repeatedly in the same solution without loosing its effectiveness. The results suggest usage of cytochrome c{sub 3} to develop innovative and environmentally benign methods to remove heavy metals from waste- and groundwater.

  18. Homotropic cooperativity of monomeric cytochrome P450 3A4

    Energy Technology Data Exchange (ETDEWEB)

    Baas, Bradley J.; Denisov, Ilia G.; Sligar, Stephen G. (UIUC)

    2010-11-16

    Mechanistic studies of mammalian cytochrome P450s are often obscured by the phase heterogeneity of solubilized preparations of membrane enzymes. The various protein-protein aggregation states of microsomes, detergent solubilized cytochrome or a family of aqueous multimeric complexes can effect measured substrate binding events as well as subsequent steps in the reaction cycle. In addition, these P450 monooxygenases are normally found in a membrane environment and the bilayer composition and dynamics can also effect these catalytic steps. Here, we describe the structural and functional characterization of a homogeneous monomeric population of cytochrome P450 3A4 (CYP 3A4) in a soluble nanoscale membrane bilayer, or Nanodisc [Nano Lett. 2 (2002) 853]. Cytochrome P450 3A4:Nanodisc assemblies were formed and purified to yield a 1:1 ratio of CYP 3A4 to Nanodisc. Solution small angle X-ray scattering was used to structurally characterize this monomeric CYP 3A4 in the membrane bilayer. The purified CYP 3A4:Nanodiscs showed a heretofore undescribed high level of homotropic cooperativity in the binding of testosterone. Soluble CYP 3A4:Nanodisc retains its known function and shows prototypic hydroxylation of testosterone when driven by hydrogen peroxide. This represents the first functional characterization of a true monomeric preparation of cytochrome P450 monooxygenase in a phospholipid bilayer and elucidates new properties of the monomeric form.

  19. SERR Spectroelectrochemical Study of Cytochrome cd1 Nitrite Reductase Co-Immobilized with Physiological Redox Partner Cytochrome c552 on Biocompatible Metal Electrodes.

    Directory of Open Access Journals (Sweden)

    Célia M Silveira

    Full Text Available Cytochrome cd1 nitrite reductases (cd1NiRs catalyze the one-electron reduction of nitrite to nitric oxide. Due to their catalytic reaction, cd1NiRs are regarded as promising components for biosensing, bioremediation and biotechnological applications. Motivated by earlier findings that catalytic activity of cd1NiR from Marinobacter hydrocarbonoclasticus (Mhcd1 depends on the presence of its physiological redox partner, cytochrome c552 (cyt c552, we show here a detailed surface enhanced resonance Raman characterization of Mhcd1 and cyt c552 attached to biocompatible electrodes in conditions which allow direct electron transfer between the conducting support and immobilized proteins. Mhcd1 and cyt c552 are co-immobilized on silver electrodes coated with self-assembled monolayers (SAMs and the electrocatalytic activity of Ag // SAM // Mhcd1 // cyt c552 and Ag // SAM // cyt c552 // Mhcd1 constructs is tested in the presence of nitrite. Simultaneous evaluation of structural and thermodynamic properties of the immobilized proteins reveals that cyt c552 retains its native properties, while the redox potential of apparently intact Mhcd1 undergoes a ~150 mV negative shift upon adsorption. Neither of the immobilization strategies results in an active Mhcd1, reinforcing the idea that subtle and very specific interactions between Mhcd1 and cyt c552 govern efficient intermolecular electron transfer and catalytic activity of Mhcd1.

  20. Cox1 mutation abrogates need for Cox23 in cytochrome c oxidase biogenesis

    Directory of Open Access Journals (Sweden)

    Richard Dela Cruz

    2016-06-01

    Full Text Available Cox23 is a known conserved assembly factor for cytochrome c oxidase, although its role in cytochrome c oxidase (CcO biogenesis remains unresolved. To gain additional insights into its role, we isolated spontaneous suppressors of the respiratory growth defect in cox23∆ yeast cells. We recovered independent colonies that propagated on glycerol/lactate medium for cox23∆ cells at 37°C. We mapped these mutations to the mitochondrial genome and specifically to COX1 yielding an I101F substitution. The I101F Cox1 allele is a gain-of-function mutation enabling yeast to respire in the absence of Cox23. CcO subunit steady-state levels were restored with the I101F Cox1 suppressor mutation and oxygen consumption and CcO activity were likewise restored. Cells harboring the mitochondrial genome encoding I101F Cox1 were used to delete genes for other CcO assembly factors to test the specificity of the Cox1 mutation as a suppressor of cox23∆ cells. The Cox1 mutant allele fails to support respiratory growth in yeast lacking Cox17, Cox19, Coa1, Coa2, Cox14 or Shy1, demonstrating its specific suppressor activity for cox23∆ cells.

  1. Mechanisms of Cytochrome C Extraction by Reverse Micelles

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The extraction of cytochrome C was carried out by means of phase transfer technique with three different reverse micellar systems, i.e., a CTAB micellar solution in n-butyl alcohol-chloroform(volume ratio 4∶1), an AOT micellar solution in isooctane and a SDSS-D2EHPA micellar solution in isooctane. The extraction mechanisms were studied. The results show that the extraction mechanisms for the same proteins with different types of reverse micellar systems can be distinct. The extraction of cytochrome C with CTAB and SDSS-D2EHPA reverse micellar systems are carried out according to the mechanism of electrostatic interaction. However, in the extraction of cytochrome C with the AOT reverse micellar system, the electrostatic interaction between the protein and the surfactant is not important.

  2. How hydrogen peroxide is metabolized by oxidized cytochrome c oxidase.

    Science.gov (United States)

    Jancura, Daniel; Stanicova, Jana; Palmer, Graham; Fabian, Marian

    2014-06-10

    In the absence of external electron donors, oxidized bovine cytochrome c oxidase (CcO) exhibits the ability to decompose excess H2O2. Depending on the concentration of peroxide, two mechanisms of degradation were identified. At submillimolar peroxide concentrations, decomposition proceeds with virtually no production of superoxide and oxygen. In contrast, in the millimolar H2O2 concentration range, CcO generates superoxide from peroxide. At submillimolar concentrations, the decomposition of H2O2 occurs at least at two sites. One is the catalytic heme a3-CuB center where H2O2 is reduced to water. During the interaction of the enzyme with H2O2, this center cycles back to oxidized CcO via the intermediate presence of two oxoferryl states. We show that at pH 8.0 two molecules of H2O2 react with the catalytic center accomplishing one cycle. In addition, the reactions at the heme a3-CuB center generate the surface-exposed lipid-based radical(s) that participates in the decomposition of peroxide. It is also found that the irreversible decline of the catalytic activity of the enzyme treated with submillimolar H2O2 concentrations results specifically from the decrease in the rate of electron transfer from heme a to the heme a3-CuB center during the reductive phase of the catalytic cycle. The rates of electron transfer from ferrocytochrome c to heme a and the kinetics of the oxidation of the fully reduced CcO with O2 were not affected in the peroxide-modified CcO.

  3. Hybrid cytochromes P-450 identify a substrate binding domain in P-450IIC5 and P-450IIC4.

    OpenAIRE

    Kronbach, T; Larabee, T M; Johnson, E F

    1989-01-01

    The cytochrome P-450 superfamily of enzymes catalyzes the oxidative metabolism of innumerable lipophilic compounds (e.g., drugs, carcinogens, steroids). Although the three-dimensional structure of a soluble bacterial P-450 (P-450cam) has been solved, little is known about the structures of the membrane-bound mammalian P-450s. Thus, the structural features of these enzymes that determine their multisubstrate specificity are unknown. In this report, we identify a segment of the primary structur...

  4. Tumor necrosis factor receptor-associated protein 1 improves hypoxia-impaired energy production in cardiomyocytes through increasing activity of cytochrome c oxidase subunit II.

    Science.gov (United States)

    Xiang, Fei; Ma, Si-Yuan; Zhang, Dong-Xia; Zhang, Qiong; Huang, Yue-Sheng

    2016-10-01

    Tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes against hypoxia, but the underlying mechanisms are not completely understood. In the present study, we used gain- and loss-of-function approaches to explore the effects of tumor necrosis factor receptor-associated protein 1 and cytochrome c oxidase subunit II on energy production in hypoxic cardiomyocytes. Hypoxia repressed ATP production in cultured cardiomyocytes, whereas overexpression of tumor necrosis factor receptor-associated protein 1 significantly improved ATP production. Conversely, knockdown of tumor necrosis factor receptor-associated protein 1 facilitated the hypoxia-induced decrease in ATP synthesis. Further investigation revealed that tumor necrosis factor receptor-associated protein 1 induced the expression and activity of cytochrome c oxidase subunit II, a component of cytochrome c oxidase that is important in mitochondrial respiratory chain function. Moreover, lentiviral-mediated overexpression of cytochrome c oxidase subunit II antagonized the decrease in ATP synthesis caused by knockdown of tumor necrosis factor receptor-associated protein 1, whereas knockdown of cytochrome c oxidase subunit II attenuated the increase in ATP synthesis caused by overexpression of tumor necrosis factor receptor-associated protein 1. In addition, inhibition of cytochrome c oxidase subunit II by a specific inhibitor sodium azide suppressed the ATP sy nthesis induced by overexpressed tumor necrosis factor receptor-associated protein 1. Hence, tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes from hypoxia at least partly via potentiation of energy generation, and cytochrome c oxidase subunit II is one of the downstream effectors that mediates the tumor necrosis factor receptor-associated protein 1-mediated energy generation program.

  5. Combining in silico protein stability calculations with structure-function relationships to explore the effect of polymorphic variation on cytochrome P450 drug metabolism.

    Science.gov (United States)

    Arendse, Lauren; Blundell, Tom L; Blackburn, Jonathan

    2013-09-01

    We carried out an in silico structural analysis of 348 non-synonymous single nucleotide polymorphisms, found across nine of the major human drug metabolising cytochrome P450 isoforms, to determine the effects of mutations on enzyme structure and function. Previous functional studies in our group have delineated regions of the cytochrome P450 structure important for substrate recognition, substrate and product access and egress from the active site and interaction with the cytochrome P450 reductase. Here we combine the information from those studies with new in silico calculations on the effect of mutations on protein stability and we compare our results to experimental data in order to establish the likely causes of altered drug metabolism observed for cytochrome P450 variants in functional assays to date, in the process creating a cytochrome P450 polymorphic variant map. Using the computational tool Site Directed Mutator we predicted destabilising mutations that result in altered enzyme function in vitro with a specificity of 83%. We found that 75% of all cytochrome P450 mutations that show altered activity in vitro are either predicted to be destabilising to protein structure or are found within regions predicted to be important for catalytic activity. Furthermore, we found that 70% of the mutations that showed similar activity to the wild-type enzyme in in vitro studies lie outside of functional regions important for catalytic activity and are predicted to have no effect on protein stability. Our resultant cytochrome P450 polymorphic variant map should therefore find utility in predicting the likely functional effect of uncharacterised variants on drug metabolism.

  6. Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models

    CERN Document Server

    Nieva, Maria-Fernanda; 10.1051/0004-6361/201118158

    2012-01-01

    Aims. A sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Present-day abundances for the astrophysically most interesting chemical elements are derived. Methods. High-resolution and high-S/N spectra of early B-type stars are analysed in NLTE. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equilibria and the hydrogen Balmer lines. Results. Teff is constrained to 1-2% and logg to less than 15% uncertainty. Absolute values for metal abundances are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spectral range. Conclusions. A present-day cosmic abundance standard is established. Our results i) resolve the discrepancy between a chemical homogeneous local gas-phase ISM and a chemically inhomogeneous young stellar component, ii) facilitate the amount of heavy elements locked up in the interstel...

  7. The role of protein dynamics and thermal fluctuations in regulating cytochrome c/cytochrome c oxidase electron transfer.

    Science.gov (United States)

    Alvarez-Paggi, Damian; Zitare, Ulises; Murgida, Daniel H

    2014-07-01

    In this overview we present recent combined electrochemical, spectroelectrochemical, spectroscopic and computational studies from our group on the electron transfer reactions of cytochrome c and of the primary electron acceptor of cytochrome c oxidase, the CuA site, in biomimetic complexes. Based on these results, we discuss how protein dynamics and thermal fluctuations may impact on protein ET reactions, comment on the possible physiological relevance of these results, and finally propose a regulatory mechanism that may operate in the Cyt/CcO electron transfer reaction in vivo. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.

  8. Single catalytic site model for the oxidation of ferrocytochrome c by mitochondrial cytochrome c oxidase.

    OpenAIRE

    Speck, S.H.; Dye, D.; Margoliash, E

    1984-01-01

    A single catalytic site model is proposed to account for the multiphasic kinetics of oxidation of ferrocytochrome c by cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). This model involves nonproductive binding of substrate to sites near the catalytic site on cytochrome c oxidase for cytochrome c, decreasing the binding constant for cytochrome c at the catalytic site. This substrate inhibition results in an increase in the first-order rate constant for the dissociati...

  9. Reference Intervals for N-Terminal Pro-B-Type Natriuretic Peptide in Amniotic Fluid between 10 and 34 Weeks of Gestation

    OpenAIRE

    Merz, Waltraut M.; Christina Leufgen; Rolf Fimmers; Birgit Stoffel-Wagner; Ulrich Gembruch

    2014-01-01

    BACKGROUND: In adult and pediatric cardiology, n-terminal pro-B-type natriuretic peptide (nt-proBNP) serves as biomarker in the diagnosis and management of cardiovascular dysfunction. Elevated levels of circulating nt-proBNP are present in fetal conditions associated with myocardial pressure or volume load. Compared to fetal blood sampling, amniocentesis is technically easier and can be performed from early pregnancy onwards. We aimed to investigate amniotic fluid (AF) nt-proBNP concentration...

  10. B超诊断输尿管结石的价值%Diagnostic value of B type ultrasound in ureteral calculi

    Institute of Scientific and Technical Information of China (English)

    李成

    2010-01-01

    Objective To evaluate the diagnostic value of B type ultrasound in ureteral calculi. Methods B type ultrasound examination were performed on 100 cases with ureteral calculi who were confirmed by open surgery, extracorporeal shock wave lithotripsy and comprehensive therapy. Results The diagnostic accuracy was 94. 00% in 100 cases,no false positive was found,and the rate of missed diagnosis was 6.00% (6 cases). Conclusion B type ultrasound has a high application value in the diagnosis of ureteral calculi, which has low false positive rate and can clear display negative stone. It can also afford some accurate clues for diagnosis and clinical treatment in tihe according to abdomenal B type ultrasound and it will be preferred in way for diagnosis of acute nephrite colic especially in basic hospitals.%目的 评价B超在输尿管结石中的诊断价值.方法 对100例经手术取石、体外震波碎石和综合疗法排石证实为输尿管结石患者进行B超检查诊断分析.结果 本组100例输尿管结石患者中,B超诊断正确率为94.00%,无假阳性,漏诊6例,占6.00%.结论 B超诊断输尿管结石假阳性率低,可清晰显示X线阴性结石,有较高的临床应用价值和为临床及时准确地提供诊断和治疗依据,是急性肾绞痛的首选检查方法,特别是在基层医疗单位为首选检查方法.

  11. Expression of Cytochrome P450nor in Escherichia coli, Purification and Preparation of Polyclonal Antibodies

    Institute of Scientific and Technical Information of China (English)

    周建刚; 张山; 陈舒丽; 江月; 刘德立

    2004-01-01

    Cytoehrome P450nor gene was cloned into the expression vector pET-28 to yield the recombinant expression plasmid pET-P450nor, which could direct the synthesis of a eukaryotic derived protein in Escherichia coli BL21. The vector allows overproduction and single-step purification of (His)6-tagged cytoehrome P450nor by the facifitation of metal (Ni2+ )chelate afl]nity chromatography. The expression level of cytoehrome P450nor was high at 30℃ after IPTG induction. SDSPAGE and Western blot analysis showed a specific band (about 43 kDa). The overproduced cytochrome P450nor was purified to eleetrophoretic homogeneity within 2.5 h and about 20.8 mg purified protein was obtained from 2 L cell culture. The proliferation of SSMC-7721 cell line could be inhibited by cytoehrome P450nor. Rabbit polyclonal antibodies (titer over 64 000) were produced against recombinant cytoehrome P450nor and proved to be very useful for immunoblotting study. Availability of this expression system and specific antibodies should facilitate characterization of the role of cytochrome P450nor in the metabolism of NO.

  12. Investigating the role of the physiological isoform switch of cytochrome c oxidase subunits in reversible mitochondrial disease.

    Science.gov (United States)

    Boczonadi, Veronika; Giunta, Michele; Lane, Maria; Tulinius, Mar; Schara, Ulrike; Horvath, Rita

    2015-06-01

    Reversible infantile respiratory chain deficiency is characterised by spontaneous recovery of mitochondrial myopathy in infants. We studied whether a physiological isoform switch of nuclear cytochrome c oxidase subunits contributes to the age-dependent manifestation and spontaneous recovery in reversible mitochondrial disease. Some nuclear-encoded subunits of cytochrome c oxidase are present as tissue-specific isoforms. Isoforms of subunits COX6A and COX7A expressed in heart and skeletal muscle are different from isoforms expressed in the liver, kidney and brain. Furthermore, in skeletal muscle both the heart and liver isoforms of subunit COX7A have been demonstrated with variable levels, indicating that the tissue-specific expression of nuclear-encoded subunits could provide a basis for the fine-tuning of cytochrome c oxidase activity to the specific metabolic needs of the different tissues. We demonstrate a developmental isoform switch of COX6A and COX7A subunits in human and mouse skeletal muscle. While the liver type isoforms are more present soon after birth, the heart/muscle isoforms gradually increase around 3 months of age in infants, 4 weeks of age in mice, and these isoforms persist in muscle throughout life. Our data in follow-up biopsies of patients with reversible infantile respiratory chain deficiency indicate that the physiological isoform switch does not contribute to the clinical manifestation and to the spontaneous recovery of this disease. However, understanding developmental changes of the different cytochrome c oxidase isoforms may have implications for other mitochondrial diseases. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.

  13. Myopericarditis with predominantly right ventricular involvement with normal B-type natriuretic peptide and cardiac tamponade as the initial manifestation of systemic lupus erythematosus.

    Science.gov (United States)

    Manautou, Luis; Jerjes-Sanchez, Carlos; Meraz, Manuel; Perez-Garcia, Luis F; Diaz-Cid, Antonio; de la Peña-Almaguer, Erasmo; Avila, Cesar; Sanchez, Luis

    2014-08-01

    A previously healthy young man presented with a 12-hour history of sudden dyspnea and severe chest pain at rest. Initial findings of physical examination, electrocardiogram and chest radiography showed typical pericarditis and clinical instability. Echocardiogram revealed small pericardial effusion with right ventricle dilatation. The patient was admitted in the ICU; a new echocardiogram revealed moderate pericardial effusion and diagnosis of pericarditis complicated with acute cardiac tamponade was established. The patient transiently improved after pericardial window. In the following hours, the diagnosis of myocarditis with predominantly right ventricular involvement (MPRVI) with severe right heart failure was supported by clinical, chest radiography and echocardiogram data, despite normal B-type natriuretic peptide. On day 2, cardiac troponin I detection was observed. By day 3, B-type natriuretic peptide in the range of ventricular dysfunction was identified. Cardiovascular magnetic resonance findings supported the diagnosis of MPRVI. A systematic MEDLINE/PubMed from 1993 to 2013 does not identify any cases of MPRVI related to systemic lupus erythematosus. Simultaneous acute MPRVI with normal B-type natriuretic peptide and acute cardiac tamponade heralding the diagnosis of systemic lupus erythematosus, to the best of our knowledge, has not been previously described.

  14. B类滤毒罐防护磷化氢性能评价探讨%Evaluation of B-Type Canister Protective Performance against Phosphine

    Institute of Scientific and Technical Information of China (English)

    汪东旺; 李泽; 赵鑫华; 尹维东; 李志坚; 元以栋

    2012-01-01

    磷化氢是粮食仓储企业使用效果最好的杀虫剂,是一种剧毒的气体熏蒸剂。所以对于从业人员来讲,安全防护就显得格外重要。长期以来粮食仓储企业一直使用自吸过滤式防毒面具(配套选用B类滤毒罐)为首选器材。近期业内对B类滤毒罐防护磷化氢的有效性提出质疑,为此,本文通过性能评价试验,说明B类滤毒罐防护磷化氢是有效的,并从理论上说明B类滤毒罐防护磷化氢是有科学依据的。%Phosphine is the best pesticides of the grain storage enterprise, and is the toxic gaseous fumigant. For users, it is important for the security. For a long time, the grain storage enterprise uses the serf-absorption filtering gas mask (selecting the B-type canister) . Recently, the protective performance against phosphine of B-type canister is doubted, through the test, this paper will explain the effective and scientific theory of B-type canister.

  15. How important is intestinal cytochrome P450 3A metabolism?

    NARCIS (Netherlands)

    Herwaarden, A.E. van; Waterschoot, R.A. van; Schinkel, A.H.

    2009-01-01

    Cytochrome P450 3A (CYP3A) enzymes metabolize a wide variety of xenobiotics including many drugs. Because CYP3A is localized in both the liver and intestine, it can make a major contribution to the presystemic elimination of substrate drugs after oral administration ('first-pass metabolism'). Howeve

  16. Trends in predicted chemoselectivity of cytochrome P450 oxidation

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Lonsdale, Richard; Harvey, Jeremy N;

    2014-01-01

    Prediction of epoxide formation in drug metabolism is a difficult but important task, as epoxide formation is linked to drug toxicity. A comparison of the energy barriers for cytochrome P450 mediated epoxidation of alkenes to the barriers for the hydroxylation of an aliphatic carbon atom next to ...

  17. Molecular dynamics in cytochrome c oxidase Moessbauer spectra deconvolution

    Energy Technology Data Exchange (ETDEWEB)

    Bossis, Fabrizio [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy); Palese, Luigi L., E-mail: palese@biochem.uniba.it [Department of Medical Biochemistry, Medical Biology and Medical Physics (DIBIFIM), University of Bari ' Aldo Moro' , Bari (Italy)

    2011-01-07

    Research highlights: {yields} Cytochrome c oxidase molecular dynamics serve to predict Moessbauer lineshape widths. {yields} Half height widths are used in modeling of Lorentzian doublets. {yields} Such spectral deconvolutions are useful in detecting the enzyme intermediates. -- Abstract: In this work low temperature molecular dynamics simulations of cytochrome c oxidase are used to predict an experimentally observable, namely Moessbauer spectra width. Predicted lineshapes are used to model Lorentzian doublets, with which published cytochrome c oxidase Moessbauer spectra were simulated. Molecular dynamics imposed constraints to spectral lineshapes permit to obtain useful information, like the presence of multiple chemical species in the binuclear center of cytochrome c oxidase. Moreover, a benchmark of quality for molecular dynamic simulations can be obtained. Despite the overwhelming importance of dynamics in electron-proton transfer systems, limited work has been devoted to unravel how much realistic are molecular dynamics simulations results. In this work, molecular dynamics based predictions are found to be in good agreement with published experimental spectra, showing that we can confidently rely on actual simulations. Molecular dynamics based deconvolution of Moessbauer spectra will lead to a renewed interest for application of this approach in bioenergetics.

  18. Cytochrome allelic variants and clopidogrel metabolism in cardiovascular diseases therapy.

    Science.gov (United States)

    Jarrar, Mohammed; Behl, Shalini; Manyam, Ganiraju; Ganah, Hany; Nazir, Mohammed; Nasab, Reem; Moustafa, Khaled

    2016-06-01

    Clopidogrel and aspirin are among the most prescribed dual antiplatelet therapies to treat the acute coronary syndrome and heart attacks. However, their potential clinical impacts are a subject of intense debates. The therapeutic efficiency of clopidogrel is controlled by the actions of hepatic cytochrome P450 (CYPs) enzymes and impacted by individual genetic variations. Inter-individual polymorphisms in CYPs enzymes affect the metabolism of clopidogrel into its active metabolites and, therefore, modify its turnover and clinical outcome. So far, clinical trials fail to confirm higher or lower adverse cardiovascular effects in patients treated with combinations of clopidogrel and proton pump inhibitors, compared with clopidogrel alone. Such inconclusive findings may be due to genetic variations in the cytochromes CYP2C19 and CYP3A4/5. To investigate potential interactions/effects of these cytochromes and their allele variants on the treatment of acute coronary syndrome with clopidogrel alone or in combination with proton pump inhibitors, we analyze recent literature and discuss the potential impact of the cytochrome allelic variants on cardiovascular events and stent thrombosis treated with clopidogrel. The diversity of CYP2C19 polymorphisms and prevalence span within various ethnic groups, subpopulations and demographic areas are also debated.

  19. Structure-Function of the Cytochrome b6f Complex of Oxygenic Photosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, W. A.; Yamashita, E.; Baniulis, D.; Whitelegge, J.; Hasan, S. S. [Lithuanian RAF; (UCLA); (Purdue); (Osaka)

    2014-03-20

    Structure–function of the major integral membrane cytochrome b6f complex that functions in cyanobacteria, algae, and green plants to transfer electrons between the two reaction center complexes in the electron transport chain of oxygenic photosynthesis is discussed in the context of recently obtained crystal structures of the complex and soluble domains of cytochrome f and the Rieske iron–sulfur protein. The energy-transducing function of the complex, generation of the proton trans-membrane electrochemical potential gradient, centers on the oxidation/reduction pathways of the plastoquinol/plastoquinone (QH2/Q), the proton donor/acceptor within the complex. These redox reactions are carried out by five redox prosthetic groups embedded in each monomer, the high potential two iron–two sulfur cluster and the heme of cytochrome f on the electropositive side (p) of the complex, two noncovalently bound b-type hemes that cross the complex and the membrane, and a covalently bound c-type heme (cn) on the electronegative side (n). These five redox-active groups are organized in high- (cyt f/[2Fe–2S] and low-potential (hemes bp, bn, cn) electron transport pathways that oxidize and reduce the quinol and quinone on the p- and n-sides in a Q-cycle-type mechanism, while translocating as many as 2 H+ to the p-side aqueous side for every electron transferred through the high potential chain to the photosystem I reaction center. The presence of heme cn and the connection of the n-side of the membrane and b6f complex to the cyclic electron transport chain indicate that the Q cycle in the oxygenic photosynthetic electron transport chain differs from those connected to the bc1 complex in the mitochondrial respiratory chain and the chain in photosynthetic bacteria. Inferences from the structure and C2 symmetry of the complex for the pathway of QH2/Q transfer

  20. Electron-paramagnetic-resonance studies of structure and function of the two-haem enzymes Pseudomonas cytochrome c peroxidase and beef heart cytochrome c oxidase.

    Science.gov (United States)

    Vänngård, T

    1985-06-01

    Beef heart cytochrome c oxidase contains two cytochromes, a and a3, and Pseudomonas aeruginosa cytochrome c peroxidase has one high- and one low-potential c haem, cHP and cLP. The parallelism in co-ordination and spin states between cytochrome a and haem cHP on the one hand and between cytochrome a3 and haem cLP on the other is illustrated. The two latter haems become accessible to cyanide, when the former are reduced. Such reduction also leads to an activation of the enzymes. Mechanisms are presented in which ferryl forms of cytochromes a3 and haem cLP take part. The enzymes reach an oxidation state, formally the same as resting enzyme, but with different properties.

  1. Effects of 3G cell phone exposure on the structure and function of the human cytochrome P450 reductase.

    Science.gov (United States)

    Tanvir, Shazia; Thuróczy, György; Selmaoui, Brahim; Silva Pires Antonietti, Viviane; Sonnet, Pascal; Arnaud-Cormos, Delia; Lévêque, Philippe; Pulvin, Sylviane; de Seze, René

    2016-10-01

    Cell phones increase exposure to radiofrequency (RF) electromagnetic fields (EMFs). Whether EMFs exert specific effects on biological systems remains debatable. This study investigated the effect of cell phone exposure on the structure and function of human NADPH-cytochrome P450 reductase (CPR). CPR plays a key role in the electron transfer to cytochrome P450, which takes part in a wide range of oxidative metabolic reactions in various organisms from microbes to humans. Human CPR was exposed for 60min to 1966-MHz RF inside a transverse electromagnetic cell (TEM-cell) placed in an incubator. The specific absorption rate (SAR) was 5W·kg(-1). Conformation changes have been detected through fluorescent spectroscopy of flavin and tryptophan residues, and investigated through circular dichroism, dynamic light scattering and microelectrophoresis. These showed that CPR was narrowed. By using cytochrome C reductase activity to assess the electron flux through the CPR, the Michaelis Menten constant (Km) and the maximum initial velocity (Vmax) decreased by 22% as compared with controls. This change was due to small changes in the tertiary and secondary structures of the protein at 37°C. The relevance of these findings to an actual RF exposure scenario demands further biochemical and in-vivo confirmation.

  2. Highly miniaturized formats for in vitro drug metabolism assays using vivid fluorescent substrates and recombinant human cytochrome P450 enzymes.

    Science.gov (United States)

    Trubetskoy, Olga V; Gibson, Jasmin R; Marks, Bryan D

    2005-02-01

    Highly miniaturized P450 screening assays designed to enable facile analysis of P450 drug interactions in a 1536-well plate format with the principal human cytochrome P450 enzymes (CYP3A4, 2D6, 2C9, 2C19, and 1A2) and Vivid fluorogenic substrates were developed. The detailed characterization of the assays included stability, homogeneity, and reproducibility of the recombinant P450 enzymes and the kinetic parameters of their reactions with Vivid fluorogenic substrates, with a focus on the specific characteristics of each component that enable screening in a low-volume 1536-well plate assay format. The screening assays were applied for the assessment of individual cytochrome P450 inhibition profiles with a panel of selected assay modifiers, including isozyme-specific substrates and inhibitors. IC(50) values obtained for the modifiers in 96- and 1536-well plate formats were similar and comparable with values obtained in assays with conventional substrates. An overall examination of the 1536-well assay statistics, such as signal-to-background ratio and Z' factor, demonstrated that these assays are a robust, successful, and reliable tool to screen for cytochrome P450 metabolism and inhibition in an ultra-high-throughput screening format.

  3. Electrochemistry suggests proton access from the exit site to the binuclear center in Paracoccus denitrificans cytochrome c oxidase pathway variants.

    Science.gov (United States)

    Meyer, Thomas; Melin, Frédéric; Richter, Oliver-M H; Ludwig, Bernd; Kannt, Aimo; Müller, Hanne; Michel, Hartmut; Hellwig, Petra

    2015-02-27

    Two different pathways through which protons access cytochrome c oxidase operate during oxygen reduction from the mitochondrial matrix, or the bacterial cytoplasm. Here, we use electrocatalytic current measurements to follow oxygen reduction coupled to proton uptake in cytochrome c oxidase isolated from Paracoccus denitrificans. Wild type enzyme and site-specific variants with defects in both proton uptake pathways (K354M, D124N and K354M/D124N) were immobilized on gold nanoparticles, and oxygen reduction was probed electrochemically in the presence of varying concentrations of Zn(2+) ions, which are known to inhibit both the entry and the exit proton pathways in the enzyme. Our data suggest that under these conditions substrate protons gain access to the oxygen reduction site via the exit pathway.

  4. Induction of Apoptosis in Purified Nuclei from Tobacco-Suspension Cells by Cytochrome b6/f Complex

    Institute of Scientific and Technical Information of China (English)

    张贵友; 李萍; 朱瑞宇; 田瑞华; 戴尧仁

    2004-01-01

    An apoptotic cell-free system containing cytosol and nuclei from normally cultured tobacco suspension cells was used to show that a spinach chloroplast preparation can induce apoptosis in nuclei,evidenced by DNA electrophoresis and fluorescence microscopy observations.Further study showed that the chloroplast preparation or its pellet (thylakoid membrane) after hypoosmotic or supersonic treatment still exhibited the apoptosis-inducing activity,but the supernatant had no effect,which indicates that the apoptosis-inducing effector in the chloroplast preparation is water-insoluble.The induction of apoptosis by chloroplast preparation could be attenuated by Ac-DEVD-CHO,the specific inhibitor of Caspase-3,implying involvement of a Caspase-3-like protease during the process.Furthermore,extensive apoptosis in nuclei was induced by cytochrome b6/f on the thylakoid membrane,indicating that this important cytochrome complex may have an important role in the chloroplast-related apoptotic pathway.

  5. Cytochrome b558/566 from the archaeon Sulfolobus acidocaldarius has a unique Asn-linked highly branched hexasaccharide chain containing 6-sulfoquinovose.

    Science.gov (United States)

    Zähringer, U; Moll, H; Hettmann, T; Knirel, Y A; Schäfer, G

    2000-07-01

    Cytochrome b558/566 from the archaeon Sulfolobus acidocaldarius (DSM 639) has been described as a novel highly glycosylated membrane-bound b-type hemoprotein [Hettmann, T., Schmidt, C. L., Anemüller, S., Zähringer, U., Moll, H., Petersen, A. & Schäfer, G. (1998) J. Biol. Chem. 273, 12032-12040]. The purified cytochrome b558/566 was characterized by MALDI MS as a 64-kDa (glyco)protein expressing 17% glycosylation. Detailed chemical studies showed that it was exclusively O-mannosylated with monosaccharides and N-glycosylated with at least seven hexasaccharide units having the same unique structure. The hexasaccharide was released by cleavage with peptide:N-glycosidase (PNGase) F and found to consist of two residues each of Man and GlcNAc and one residue each of Glc and 6-deoxy-6-sulfoglucose (6-sulfoquinovose). The last sugar has been known as a component of glycolipids of plants and some prokaryotes, but has not been hitherto found in bacterial glycoproteins. Digestion with trypsin/pronase gave a mixture of glycopeptides with the same Asn-linked hexasaccharide chain, from which an N-glycosylated Tyr-Asn dipeptide was purified by gel chromatography and anion-exchange HPLC. Studies of the degradation products using methylation analysis, ESI MS, MALDI MS, and 1H and 13C NMR spectroscopy, including 1H,13C HMQC and NOESY experiments, established the structure of the unique Asn-linked hexasaccharide chain of cytochrome b558/566.

  6. Effect of urea on synchronous fluorescence spectra and electrochemical behaviour of cytochrome

    Institute of Scientific and Technical Information of China (English)

    侴菊; 陆天虹; 吴越

    1996-01-01

    The changes of the synchronous fluorescence spectra and the electrochemical behaviour of cytochrome c with the urea concentration are studied. It has been found that with the increase of urea concentration, there occur sequentially the deaggregation of cytochrome c molecules, the increase of exposure extent of the heme group to the solvent, the disruption of Fe-S bond of the heme group and the change in the electrochemical behaviour of cytochrome c. It is suggested that the reason why the electrochemical reaction of cytochrome c is irreversible is that cytochrome c molecules exist in the concentrated solution as oligomers which are electrochemically inactive.

  7. Purification of a cytochrome bc1-aa3 supercomplex with quinol oxidase activity from Corynebacterium glutamicum

    OpenAIRE

    Niebisch, A.; Bott, M.

    2003-01-01

    The aerobic respiratory chain of the Gram-positive Corynebacterium glutamicum involves a bc(1) complex with a diheme cytochrome c(1) and a cytochrome aa(3) oxidase but no additional c-type cytochromes. Here we show that the two enzymes form a supercomplex, because affinity chromatography of either strep-tagged cytochrome b (QcrB) or strep-tagged subunit I (CtaD) of cytochrome aa(3) always resulted in the copurification of the subunits of the bc(1) complex (QcrA, QcrB, QcrC) and the aa(3) comp...

  8. Genetic differentiation of the mitochondrial cytochrome oxidase C subunit I gene in genus Paramecium (Protista, Ciliophora.

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    Full Text Available BACKGROUND: The mitochondrial cytochrome c oxidase subunit I (COI gene is being used increasingly for evaluating inter- and intra-specific genetic diversity of ciliated protists. However, very few studies focus on assessing genetic divergence of the COI gene within individuals and how its presence might affect species identification and population structure analyses. METHODOLOGY/PRINCIPAL FINDINGS: We evaluated the genetic variation of the COI gene in five Paramecium species for a total of 147 clones derived from 21 individuals and 7 populations. We identified a total of 90 haplotypes with several individuals carrying more than one haplotype. Parsimony network and phylogenetic tree analyses revealed that intra-individual diversity had no effect in species identification and only a minor effect on population structure. CONCLUSIONS: Our results suggest that the COI gene is a suitable marker for resolving inter- and intra-specific relationships of Paramecium spp.

  9. Structural characterization and regulatory element analysis of the heart isoform of cytochrome c oxidase VIa

    Science.gov (United States)

    Wan, B.; Moreadith, R. W.; Blomqvist, C. G. (Principal Investigator)

    1995-01-01

    In order to investigate the mechanism(s) governing the striated muscle-specific expression of cytochrome c oxidase VIaH we have characterized the murine gene and analyzed its transcriptional regulatory elements in skeletal myogenic cell lines. The gene is single copy, spans 689 base pairs (bp), and is comprised of three exons. The 5'-ends of transcripts from the gene are heterogeneous, but the most abundant transcript includes a 5'-untranslated region of 30 nucleotides. When fused to the luciferase reporter gene, the 3.5-kilobase 5'-flanking region of the gene directed the expression of the heterologous protein selectively in differentiated Sol8 cells and transgenic mice, recapitulating the pattern of expression of the endogenous gene. Deletion analysis identified a 300-bp fragment sufficient to direct the myotube-specific expression of luciferase in Sol8 cells. The region lacks an apparent TATA element, and sequence motifs predicted to bind NRF-1, NRF-2, ox-box, or PPAR factors known to regulate other nuclear genes encoding mitochondrial proteins are not evident. Mutational analysis, however, identified two cis-elements necessary for the high level expression of the reporter protein: a MEF2 consensus element at -90 to -81 bp and an E-box element at -147 to -142 bp. Additional E-box motifs at closely located positions were mutated without loss of transcriptional activity. The dependence of transcriptional activation of cytochrome c oxidase VIaH on cis-elements similar to those found in contractile protein genes suggests that the striated muscle-specific expression is coregulated by mechanisms that control the lineage-specific expression of several contractile and cytosolic proteins.

  10. Chronic exposure to sulfide causes accelerated degradation of cytochrome c oxidase in ethylmalonic encephalopathy.

    Science.gov (United States)

    Di Meo, Ivano; Fagiolari, Gigliola; Prelle, Alessandro; Viscomi, Carlo; Zeviani, Massimo; Tiranti, Valeria

    2011-07-15

    Ethylmalonic encephalopathy (EE) is an autosomal recessive, invariably fatal disorder associated with mutations in ETHE1, a gene encoding a mitochondrial sulfur dioxygenase (SDO). The main consequence of the absence of Ethe1-SDO is the accumulation of sulfide (H(2)S) in critical tissues, including colonic mucosa, liver, muscle, and brain. To make progress in the elucidation of the biochemical mechanisms leading to cytochrome c oxidase (COX) deficiency, we (i) generated tissue-specific conditional Ethe1 knockout mice to clarify the different contributions of endogenous and exogenous H(2)S production, and (ii) studied the development of H(2)S-driven COX deficiency in Ethe1(-/-) mouse tissues and human cells. Ethe1(-/-) conditional animals displayed COX deficiency limited to the specific targeted tissue. The accumulation of H(2)S over time causes progressive COX deficiency in animal tissues and human cells, which is associated with reduced amount of COX holoenzyme, and of several COX subunits, including mitochondrially encoded cytochrome c oxidase 1 (MTCO1), MTCO2, COX4, and COX5A. This reduction is not paralleled by consistent downregulation in expression of the corresponding mRNAs. Tissue-specific ablation of Ethe1 causes COX deficiency in targeted organs, suggesting that failure in neutralizing endogenous, tissue-specific production of H(2)S is sufficient to cause the biochemical defect but neither to determine a clinical impact nor to induce the biomarker profile typical of EE. The mechanism by which H(2)S causes COX deficiency consists of rapid heme a inhibition and accelerated long-term degradation of COX subunits. However, the pleiotropic devastating effects of H(2)S accumulation in EE cannot be fully explained by the sole defect of COX in critical tissues, but are likely consequent to several toxic actions on a number of enzymatic activities in different tissues, including endothelial lining of the small vessels, leading to multiorgan failure.

  11. The anticarcinogen 3,3'-diindolylmethane is an inhibitor of cytochrome P-450.

    Science.gov (United States)

    Stresser, D M; Bjeldanes, L F; Bailey, G S; Williams, D E

    1995-08-01

    Dietary indole-3-carbinol inhibits carcinogenesis in rodents and trout. Several mechanisms of inhibition may exist. We reported previously that 3,3'-diindolylmethane, an in vivo derivative of indole-3-carbinol, is a potent noncompetitive inhibitor of trout cytochrome P450 (CYP) 1A-dependent ethoxyresorufin O-deethylase with Ki values in the low micromolar range. We now report a similar potent inhibition by 3,3'-diindolylmethane of rat and human CYP1A1, human CYP1A2, and rat CYP2B1 using various CYP-specific or preferential activity assays. 3,3'-Diindolylmethane also inhibited in vitro CYP-mediated metabolism of the ubiquitous food contaminant and potent hepatocarcinogen, aflatoxin B1. There was no inhibition of cytochrome c reductase. In addition, we found 3,3'-diindolylmethane to be a substrate for rat hepatic microsomal monooxygenase(s) and tentatively identified a monohydroxylated metabolite. These observations indicate that 3,3'-diindolylmethane can inhibit the catalytic activities of a range of CYP isoforms from lower and higher vertebrates in vitro. This broadly based inhibition of CYP-mediated activation of procarcinogens may be an indole-3-carbinol anticarcinogenic mechanism applicable to all species, including humans.

  12. Prediction of drug-like molecular properties: modeling cytochrome p450 interactions.

    Science.gov (United States)

    Jalaie, Mehran; Arimoto, Rieko; Gifford, Eric; Schefzick, Sabine; Waller, Chris L

    2004-01-01

    Preventing drug-drug interactions and reducing drug-related mortalities dictate cleaner and costlier medicines. The cost to bring a new drug to market has increased dramatically over the last 10 years, with post-discovery activities (preclinical and clinical) costs representing the majority of the spend. With the ever-increasing scrutiny that new drug candidates undergo in the post-discovery assessment phases, there is increasing pressure on discovery to deliver higher-quality drug candidates. Given that compound attrition in the early clinical stages can often be attributed to metabolic liabilities, it has been of great interest lately to implement predictive measures of metabolic stability/ liability in the drug design stage of discovery. The solution to this issue is wrapped in understanding the basic of the cytochrome P450 (CYP) enzymes functions and structures. Recently, experimental information on the structure of a variety of cytochrome P450 enzymes, major contributors to phase I metabolism, has become readily available. This, coupled with the availability of experimental information on substrate specificities, has lead to the development of numerous computational models (macromolecular, pharmacophore, and structure-activity) for the rationalization and prediction of CYP liabilities. A comprehensive review of these models is presented in this chapter.

  13. Third international symposium: Cytochrome P450 biodiversity. Final report, January 1, 1995--December 31, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Loper, J.C.

    1997-03-01

    The Symposium was held on October 8-12, 1995 at the Marine Biological Laboratory in Woods Hole Massachusetts. Other international symposia promote cytochrome P450 research but have a primary focus on mammalian systems. This symposium is exclusively devoted to research in other organisms, and major topics reflect the distribution and dominance of non-mammalian species in the biosphere. The five sessions focused on basic mechanism, regulation, biodiversity, host-parasite interactions, and practical applications. 170 Scientists contributed 38 oral presentations and 91 posters, with a truly international composition of the symposium. Practical applications were a recurring feature, linking reports on mechanism and regulation to studies on the engineering of substrate specificity, microorganisms to degrade halogenated hydrocarbons and herbicides, and the production of in vitro P450 electrochemical bioreactors. At the time of the symposium there were 477 cytochrome P450 sequences in the database. Expansion of the known plant P450 genes was reported, with 20 new plant P450 families added in the last 3 years. Of these only 5 families have a physiological function associated with them. A growing number of identified invertebrate P450s was documented, where in insects, the forms identified are primarily involved in inducible xenobiotic metabolism and detoxification of toxic plant substances.

  14. A novel role of Drosophila cytochrome P450-4e3 in permethrin insecticide tolerance.

    Science.gov (United States)

    Terhzaz, Selim; Cabrero, Pablo; Brinzer, Robert A; Halberg, Kenneth A; Dow, Julian A T; Davies, Shireen-A

    2015-12-01

    The exposure of insects to xenobiotics, such as insecticides, triggers a complex defence response necessary for survival. This response includes the induction of genes that encode key Cytochrome P450 monooxygenase detoxification enzymes. Drosophila melanogaster Malpighian (renal) tubules are critical organs in the detoxification and elimination of these foreign compounds, so the tubule response induced by dietary exposure to the insecticide permethrin was examined. We found that expression of the gene encoding Cytochrome P450-4e3 (Cyp4e3) is significantly up-regulated by Drosophila fed on permethrin and that manipulation of Cyp4e3 levels, specifically in the principal cells of the Malpighian tubules, impacts significantly on the survival of permethrin-fed flies. Both dietary exposure to permethrin and Cyp4e3 knockdown cause a significant elevation of oxidative stress-associated markers in the tubules, including H2O2 and lipid peroxidation byproduct, HNE (4-hydroxynonenal). Thus, Cyp4e3 may play an important role in regulating H2O2 levels in the endoplasmic reticulum (ER) where it resides, and its absence triggers a JAK/STAT and NF-κB-mediated stress response, similar to that observed in cells under ER stress. This work increases our understanding of the molecular mechanisms of insecticide detoxification and provides further evidence of the oxidative stress responses induced by permethrin metabolism.

  15. Short-term fasting alters cytochrome P450-mediated drug metabolism in humans.

    Science.gov (United States)

    Lammers, Laureen A; Achterbergh, Roos; de Vries, Emmely M; van Nierop, F Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Boelen, Anita; Romijn, Johannes A; Mathôt, Ron A A

    2015-06-01

    Experimental studies indicate that short-term fasting alters drug metabolism. However, the effects of short-term fasting on drug metabolism in humans need further investigation. Therefore, the aim of this study was to evaluate the effects of short-term fasting (36 h) on P450-mediated drug metabolism. In a randomized crossover study design, nine healthy subjects ingested a cocktail consisting of five P450-specific probe drugs [caffeine (CYP1A2), S-warfarin (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6), and midazolam (CYP3A4)] on two occasions (control study after an overnight fast and after 36 h of fasting). Blood samples were drawn for pharmacokinetic analysis using nonlinear mixed effects modeling. In addition, we studied in Wistar rats the effects of short-term fasting on hepatic mRNA expression of P450 isoforms corresponding with the five studied P450 enzymes in humans. In the healthy subjects, short-term fasting increased oral caffeine clearance by 20% (P = 0.03) and decreased oral S-warfarin clearance by 25% (P fasting increased mRNA expression of the orthologs of human CYP1A2, CYP2C19, CYP2D6, and CYP3A4 (P fasting alters cytochrome P450-mediated drug metabolism in a nonuniform pattern. Therefore, short-term fasting is another factor affecting cytochrome P450-mediated drug metabolism in humans.

  16. Cytochrome P450 Bioconjugate as a Nanovehicle for Improved Chemotherapy Treatment.

    Science.gov (United States)

    Quester, Katrin; Juarez-Moreno, Karla; Secundino, Isamel; Roseinstein, Yvonne; Alejo, Karla P; Huerta-Saquero, Alejandro; Vazquez-Duhalt, Rafael

    2016-11-28

    Cancer is still a growing public health problem, especially breast cancer that is one of the most important cancers in women. Chemotherapy, even though a successful treatment, is accompanied by severe side effects. Moreover, most of the drugs used for chemotherapy are administered as prodrugs and need to be transformed to the active form by cytochromes P450 (CYPs). In addition, increasing numbers of cancer tissues show lower CYP activity than the surrounding healthy tissues in which prodrugs are preferentially activated causing cytotoxicity. Here, the design of a functionalized cytochrome P450 bioconjugate is reported as nanovehicle for the enzyme direct delivery to the tumor tissue in order to improve the local drug activation. MCF-7 breast cancer cells are treated with CYP-polyethylene glycol bioconjugate functionalized folic acid, where it activates the prodrug tamoxifen and significantly reduces the dose of tamoxifen needed to kill the tumor cells. The CYP bioconjugate covered with polyethylene glycol shows no immunogenic activity. The advantages of increasing the site-specific CYP activity in tumor tissues are discussed.

  17. Effect of cytochrome P450 and aldo-keto reductase inhibitors on progesterone inactivation in primary bovine hepatic cell cultures.

    Science.gov (United States)

    Lemley, C O; Wilson, M E

    2010-10-01

    Progesterone is required for maintenance of pregnancy, and peripheral concentrations of progesterone are affected by both production and inactivation. Hepatic cytochrome P450 (EC 1.14.14.1) and aldo-keto reductase (EC 1.1.1.145-151) enzymes play a pivotal role in the first step of steroid inactivation, which involves the addition of hydroxyl groups to various sites of the cyclopentanoperhydrophenanthrene nucleus. The current objective was to discern the proportional involvement of hepatic progesterone inactivating enzymes on progesterone decay using specific enzyme inhibitors. Ticlopidine, diltiazem, curcumin, dicumarol, and naproxen were used because of their selective inhibition of cytochrome P450s, aldo-keto reductases, and glucuronosyltransferases. Liver biopsies were collected from 6 lactating Holstein dairy cows, and cells were dissociated using a nonperfusion technique. Confluent wells were preincubated for 4 h with enzyme inhibitor and then challenged with progesterone for 1 h. Cell viability was unaffected by inhibitor treatment and averaged 84±1%. In control wells, 50% of the progesterone had been inactivated after a 1-h challenge with 5 ng/mL of progesterone. Preincubation with curcumin, ticlopidine, or naproxen caused the greatest reduction in progesterone inactivation compared with controls and averaged 77, 39, or 37%, respectively. Hydroxylation of 4-nitrophenol to 4-nitrocatechol in intact cells was inhibited by approximately 65% after treatment with curcumin or ticlopidine. Glucuronidation of phenol red or 4-nitrocatechol in intact cells was inhibited by treatment with curcumin, dicumarol, or naproxen. In cytoplasmic preparations, aldo-keto reductase 1C activity was inhibited by curcumin, dicumarol, or naproxen treatment. Microsomal cytochrome P450 2C activity was inhibited by treatment with curcumin or ticlopidine, whereas cytochrome P450 3A activity was inhibited by treatment with curcumin or diltiazem. The contribution of cytochrome P450 2C and

  18. Structural transformation of cytochrome c and apo cytochrome c induced by sulfonated polystyrene.

    Science.gov (United States)

    Gong, Jie; Yao, Ping; Duan, Hongwei; Jiang, Ming; Gu, Shaohua; Chunyu, Lijuan

    2003-01-01

    The structural transformation of cytochrome c (cyt c) and its heme-free precursor, apo cyt c, induced by negatively charged sulfonated polystyrene (SPS) with different charge density (degree of sulfonation) and chain length was studied to understand the factors that influence the folding and unfolding of the protein. SPS forms stable transparent nanoparticles in aqueous solution. The hydrophobic association of the backbone chain and phenyl groups is balanced by the electrostatic repulsion of the sulfonate groups on the particle surface. The binding of cyt c to negatively charged SPS particles causes an extensive disruption of the native compact structure of cyt c: the cleavage of Fe-Met80 ligand, about 40% loss of the helical structure, and the disruption of the asymmetry environment of Trp59. On the other hand, SPS particle-bound apo cyt c undergoes a conformational change from the random coil to alpha-helical structure. The folding of apo cyt c in SPS particles was influenced by pH and ionic strength of the solution, SPS concentration, and the degree of sulfonation and chain length of SPS. The folding can reach more than 90% of the alpha-helix content of native cyt c in solution. Poly(sodium 4-styrenesulfonate) (PSS), which is 100% sulfonated polystyrene and cannot form hydrophobic cores in the solution, induces only two-thirds of the alpha-helix content compared with SPS. It appears that the electrostatic interaction between PSS/SPS and apo cyt c induces an early partially folded state of apo cyt c. The hydrophobic interaction between nonpolar residues in apo cyt c and the hydrophobic cores in SPS particles extends the alpha-helical structure of apo cyt c.

  19. A novel nucleoside kinase from Burkholderia thailandensis: a member of the phosphofructokinase B-type family of enzymes.

    Science.gov (United States)

    Ota, Hiroko; Sakasegawa, Shin-Ichi; Yasuda, Yuko; Imamura, Shigeyuki; Tamura, Tomohiro

    2008-12-01

    The genome of the mesophilic Gram-negative bacterium Burkholderia thailandensis contains an open reading frame (i.e. the Bth_I1158 gene) that has been annotated as a putative ribokinase and PFK-B family member. Notably, although the deduced amino acid sequence of the gene showed only 29% similarity to the recently identified nucleoside kinase from hyperthermophilic archaea Methanocaldococcus jannaschii, 15 of 17 residues reportedly involved in the catalytic activity of M. jannaschii nucleoside kinase were conserved. The gene was cloned and functionally overexpressed in Rhodococcus erythropolis, and the purified enzyme was characterized biochemically. The substrate specificity of the enzyme was unusually broad for a bacterial PFK-B protein, and the specificity extended not only to purine and purine-analog nucleosides but also to uridine. Inosine was the most effective phosphoryl acceptor, with the highest k(cat)/K(m) value (80 s(-1).mm(-1)) being achieved when ATP served as the phosphoryl donor. By contrast, this enzyme exhibited no activity toward ribose, indicating that the recombinant enzyme was a nucleoside kinase rather than a ribokinase. To our knowledge, this is the first detailed analysis of a bacterial nucleoside kinase in the PFK-B family.

  20. Canine Recombinant Adenovirus Vector Induces an Immunogenicity-Related Gene Expression Profile in Skin-Migrated CD11b+ -Type DCs

    Science.gov (United States)

    Jouneau, Luc; Bourge, Mickael; Bouet-Cararo, Coraline; Bonneau, Michel; Zientara, Stephan; Klonjkowski, Bernard; Schwartz-Cornil, Isabelle

    2012-01-01

    Gene expression profiling of the blood cell response induced early after vaccination has previously been demonstrated to predict the immunogenicity of vaccines. In this study, we evaluated whether the analysis of the gene expression profile of skin-migrated dendritic cells (DCs) could be informative for the in vitro prediction of immunogenicity of vaccine, using canine adenovirus serotype 2 (CAV2) as vaccine vector. CAV2 has been shown to induce immunity to transgenes in several species including sheep and is an interesting alternative to human adenovirus-based vectors, based on the safety records of the parental strain in dogs and the lack of pre-existing immunity in non-host species. Skin-migrated DCs were collected from pseudo-afferent lymph in sheep. Both the CD11b+ -type and CD103+ -type skin-migrated DCs were transduced by CAV2. An analysis of the global gene response to CAV2 in the two skin DC subsets showed that the gene response in CD11b+ -type DCs was far higher and broader than in the CD103+ -type DCs. A newly released integrative analytic tool from Ingenuity systems revealed that the CAV2-modulated genes in the CD11b+ -type DCs clustered in several activated immunogenicity-related functions, such as immune response, immune cell trafficking and inflammation. Thus gene profiling in skin-migrated DC in vitro indicates that the CD11b+ DC type is more responsive to CAV2 than the CD103+ DC type, and provides valuable information to help in evaluating and possibly improving viral vector vaccine effectiveness. PMID:23300693

  1. Identification of three cytochrome P450 genes in the Chagas' disease vector Triatoma infestans: Expression analysis in deltamethrin susceptible and resistant populations.

    Science.gov (United States)

    Grosso, Carla G; Blariza, María J; Mougabure-Cueto, Gastón; Picollo, María I; García, Beatriz A

    2016-10-01

    Cytochrome P450 monooxygenases play a predominant role in the metabolism of insecticides. Many insect P450 genes have frequently been associated with detoxification processes allowing the insect to become tolerant or resistant to insecticides. The increases of expression of P450 genes at transcriptional level are often consider responsible for increasing the metabolism of insecticides and seems to be a common phenomenon in the evolution of resistance development in insects. As pyrethroid resistance has been detected in Triatoma infestans, it was of interest to analyze genes associated with resistance to insecticides such as those encoding for cytochromes P450. With this purpose, the cDNA sequences of three cytochrome P450 genes (CYP4EM7, CYP3085B1, and CYP3092A6) were identified in this species. Primers and specific Taqman probes were designed from these sequences to determine their expression by quantitative PCR. The mRNA levels of the cytochrome P450 genes identified were determined from total RNA extracted from pools of fat body collected from individuals of different resistant and susceptible strains of T. infestans, and at different interval times after the topical application of the lethal doses 50% (LD50) of deltamethrin on the ventral abdomen of insects belonging to the different populations analyzed. It was detected overexpression of the CYP4EM7 gene in the most resistant strain of T. infestans and the expression of the three cytochrome P450 genes isolated was induced by deltamethrin in the susceptible and resistant populations included in this study. These results suggest that these genes would be involved in the detoxification of deltamethrin and support the hypothesis that considers to the cytochrome P450 genes of importance in the development of pyrethroid resistance.

  2. Modulation of ligand-heme reactivity by binding pocket residues demonstrated in cytochrome c' over the femtosecond-second temporal range.

    Science.gov (United States)

    Russell, Henry J; Hardman, Samantha J O; Heyes, Derren J; Hough, Michael A; Greetham, Gregory M; Towrie, Michael; Hay, Sam; Scrutton, Nigel S

    2013-12-01

    The ability of hemoproteins to discriminate between diatomic molecules, and the subsequent affinity for their chosen ligand, is fundamental to the existence of life. These processes are often controlled by precise structural arrangements in proteins, with heme pocket residues driving reactivity and specificity. One such protein is cytochrome c', which has the ability to bind nitric oxide (NO) and carbon monoxide (CO) on opposite faces of the heme, a property that is shared with soluble guanylate cycle. Like soluble guanylate cyclase, cytochrome c' also excludes O2 completely from the binding pocket. Previous studies have shown that the NO binding mechanism is regulated by a proximal arginine residue (R124) and a distal leucine residue (L16). Here, we have investigated the roles of these residues in maintaining the affinity for NO in the heme binding environment by using various time-resolved spectroscopy techniques that span the entire femtosecond-second temporal range in the UV-vis spectrum, and the femtosecond-nanosecond range by IR spectroscopy. Our findings indicate that the tightly regulated NO rebinding events following excitation in wild-type cytochrome c' are affected in the R124A variant. In the R124A variant, vibrational and electronic changes extend continuously across all time scales (from fs-s), in contrast to wild-type cytochrome c' and the L16A variant. Based on these findings, we propose a NO (re)binding mechanism for the R124A variant of cytochrome c' that is distinct from that in wild-type cytochrome c'. In the wider context, these findings emphasize the importance of heme pocket architecture in maintaining the reactivity of hemoproteins towards their chosen ligand, and demonstrate the power of spectroscopic probes spanning a wide temporal range.

  3. Supramaximal elevation in B-type natriuretic peptide and its N-terminal fragment levels in anephric patients with heart failure: a case series

    Directory of Open Access Journals (Sweden)

    Ting John YC

    2012-10-01

    Full Text Available Abstract Introduction Little is known about the responses of natriuretic peptides to developing congestive heart failure in ‘anephric’ end-stage kidney disease. Case presentation We present three consecutive cases of surgically-induced anephric patients in a critical care environment: a 28-year-old Caucasian woman (with congestive heart failure, a 42-year-old Caucasian woman (without congestive heart failure, and a 23-year-old Caucasian woman (without congestive heart failure. Our limited study data indicate that cut-off values advocated for B-type natriuretic peptide and its N-terminal fragment to ‘rule out’ congestive heart failure in two of our end-stage kidney disease patients (without congestive heart failure are largely appropriate for anephric patients. However, our index (first patient developed congestive heart failure accompanied by the phenomenon of massive and persistent elevation of these natriuretic levels. Conclusion Our findings suggest that patients from the anephric subclass suffering from congestive heart failure will develop supramaximal elevation of B-type natriuretic peptide and its N-terminal fragment, implying the need for dramatically higher cut-off values with respective magnitudes of the order of 50-fold (B-type natriuretic peptide ~5780pmol/L; 20,000ng/L to 100-fold (N-terminal fragment ~11,800pmol/L; 100,000ng/L higher than current values used to ‘rule in’ congestive heart failure. Further research will be required to delineate those cut-off values. The role of our devised ‘Blood Volume – B-type natriuretic peptide feedback control system’ on ‘anatomical’ and ‘functional’ anephric patients led to significant mathematically-enriched arguments supporting our proposal that this model provides plausible explanations for the study findings, and the model lends support to the important hypothesis that these two groups of anephric patients inflicted with congestive heart failure should effectively

  4. Predicting drug metabolism by cytochrome P450 2C9

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Olsen, Lars

    2012-01-01

    By the use of knowledge gained through modeling of drug metabolism mediated by the cytochrome P450 2D6 and 3A4 isoforms, we constructed a 2D-based model for site-of-metabolism prediction for the cytochrome P450 2C9 isoform. The similarities and differences between the models for the 2C9 and 2D6...... isoforms are discussed through structural knowledge from the X-ray crystal structures and trends in experimental data. The final model was validated on an independent test set, resulting in an area under the curve value of 0.92, and a site of metabolism was found among the top two ranked atoms for 77...

  5. Cooperation between COA6 and SCO2 in COX2 maturation during cytochrome c oxidase assembly links two mitochondrial cardiomyopathies.

    Science.gov (United States)

    Pacheu-Grau, David; Bareth, Bettina; Dudek, Jan; Juris, Lisa; Vögtle, F-Nora; Wissel, Mirjam; Leary, Scot C; Dennerlein, Sven; Rehling, Peter; Deckers, Markus

    2015-06-02

    Three mitochondria-encoded subunits form the catalytic core of cytochrome c oxidase, the terminal enzyme of the respiratory chain. COX1 and COX2 contain heme and copper redox centers, which are integrated during assembly of the enzyme. Defects in this process lead to an enzyme deficiency and manifest as mitochondrial disorders in humans. Here we demonstrate that COA6 is specifically required for COX2 biogenesis. Absence of COA6 leads to fast turnover of newly synthesized COX2 and a concomitant reduction in cytochrome c oxidase levels. COA6 interacts transiently with the copper-containing catalytic domain of newly synthesized COX2. Interestingly, similar to the copper metallochaperone SCO2, loss of COA6 causes cardiomyopathy in humans. We show that COA6 and SCO2 interact and that corresponding pathogenic mutations in each protein affect complex formation. Our analyses define COA6 as a constituent of the mitochondrial copper relay system, linking defects in COX2 metallation to cardiac cytochrome c oxidase deficiency.

  6. Structural Diversity of Eukaryotic Membrane Cytochrome P450s*

    OpenAIRE

    Johnson, Eric F.; Stout, C. David

    2013-01-01

    X-ray crystal structures are available for 29 eukaryotic microsomal, chloroplast, or mitochondrial cytochrome P450s, including two non-monooxygenase P450s. These structures provide a basis for understanding structure-function relations that underlie their distinct catalytic activities. Moreover, structural plasticity has been characterized for individual P450s that aids in understanding substrate binding in P450s that mediate drug clearance.

  7. Special issue: Cytochrome P450 structure and function: introduction.

    Science.gov (United States)

    Munro, Andrew W; Leys, David

    2012-05-01

    The 17th International Conference on Cytochrome P450 Biochemistry, Biophysics and Structure was held in Manchester, UK from 26-30 June 2011. This issue of FEBS J. contains review and primary research articles reflecting the breadth of science covered at this conference, and reflecting the impact of P450-related research in fields as diverse as steroid metabolism, plant biochemistry, structural biology and biotechnology.

  8. Alterations in cytochrome P-450 levels in adult rats following neonatal exposure to xenobiotics

    Energy Technology Data Exchange (ETDEWEB)

    Zangar, R.C. (Oregon State Univ., Corvallis (United States) Pacific Northwest Laboratories, Richland, WA (United States)); Springer, D.L. (Pacific Northwest Laboratories, Richland, WA (United States)); Buhler, D.R. (Oregon State Univ., Corvallis (United States))

    1993-01-01

    Neonatal exposure to certain xenobiotics has been shown to alter hepatic metabolism in adult rats in a manner that indicates long-term changes in enzyme regulation. Previously, the authors have observed changes in adult testosterone metabolism and in cytochrome P-450 (P-450) mRNA levels in animals neonatally exposed to phenobarbital (PB) or diethylstilbestrol (DES). In order to test for other enzyme alterations, they used Western blot procedures for specific P-450s to analyze hepatic microsomes from adult rats (24 wk old) that had been exposed neonatally to DES, PB, 7,12-dimethylbenz[a]anthracene (DMBA), or pregnenolone 16[alpha]-carbonitrile (PCN). The most striking effects were observed in the DES-treated males: P-4502C6 and an immunologically similar protein were increased 60 and 90%, respectively, relative to control values, but P-4503A2 was decreased by 44%. No changes were observed in the DES-treated males in levels of P-4502E1, P-4502B, or the male-specific P-4502C13. Adult males neonatally treated with PB had 150% increase in levels of anti-P4502B-reactive protein without significant changes in the other enzymes. The DES- and DMBA-treated females had increased levels of the female-specific P-4502C12 of 38 and 48%, respectively, but no other observed alterations. The results confirm that neonatal exposure to DES or PB can cause alterations in adult hepatic cytochrome P-450 levels but show that these chemicals act on different enzymes. Neonatal DMBA resulted in changes in adult females similar to those produced by the synthetic estrogen DES, but did so at about two-thirds lower dose. 37 refs., 5 figs.

  9. Using Cytochrome c{sub 3} to Make Selenium Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    ABDELOUAS,A.; FRANCO,R.; GONG,W.L.; LUTZE,W.; MOURA,I.; SHELNUTT,JOHN A.

    1999-11-24

    We report on a new method to make nanostructures, in this case selenium nanowires, in aqueous solution at room temperature. We used the protein cytochrome c{sub 3} to reduce selenate (SeO{sub 4}{sup 2{minus}}) to selenium (Se{sup 0}). Cytochrome c{sub 3} is known for its ability to catalyze reduction of metals including U{sup VI} {yields} U{sup IV}, Cr{sup VI} {yields} Cr{sup III}, Mo{sup VI} {yields} Mo{sup IV}, Cu{sup II} {yields} Cu{sup 0}, Pb{sup II} {yields} Pb{sup 0}, Hg{sup II} {yields} Hg{sup 0}. Nanoparticles of Se{sup 0} precipitated from an aqueous solution at room temperature, followed by spontaneous self-assembling into nanowires. Cytochrome c{sub 3} was extracted from the sulfate-reducing bacteria Desulfovibrio vulgaris (strain Holdenborough) and isolated by the procedure of DerVartanian and Legall.

  10. Studies of multi-heme cytochromes from Geobacter sulfurreducens

    Energy Technology Data Exchange (ETDEWEB)

    Pokkuluri, P. Raj; Londer, Yuri, Y.; Orshonsky, Valerie; Orshonsky, Lisa; Duke, Norma; Schiffer, Marianne

    2006-04-05

    The Geobacteraceae family predominates in the reduction of uranium in subsurface environments. We are focusing on the model organism, Geobacter sulfurreducens; its genome contains a large number (>100) of cytochromes c that function in metal reduction pathways. Intensive functional genomics and physiological studies are in progress in Prof. Derek Lovley's laboratory, and the complete genome sequence of this organism has been determined by Methe et al. 2003. We are studying cytochromes from the c{sub 7} family that are required for the reduction of Fe(III). Previously, we expressed in E. coli (Londer et al., 2002) and determined the three-dimensional structure at 1.45 {angstrom} resolution (Pokkuluri et al., 2004a) of the three-heme cytochrome c{sub 7} (PpcA, coded by ORF01023) characterized by Lloyd et al., 2003. Further we identified in the G. sulfurreducens genome ORFs for several of its homologs (Pokkuluri et al., 2004a). Four of the ORFs are the same size as PpcA; three other ORFs are polymers of c7-type domains, two of which consist of four domains and one of nine domains, that contain 12 and 27 hemes respectively.

  11. Hydration Dependence of Energy Relaxation Time for Cytochrome C

    Science.gov (United States)

    Ye, Shuji; Chen, Jing-Yin; Knab, Joseph R.; Markelz, Andrea

    2006-03-01

    Hydration plays a critical role in protein dynamics. Here we consider the effects of hydration on energy relaxation for an electronically excited heme protein cytochrome c. We measure the hydration dependence of energy relaxation time of cytochrome C films after photoexcitation in the Soret regionusing two-color pump/probe time resolved transmission measurements. Thin films were prepared from cytochrome C/ Trizma buffer solutions and mounted in a hydration controlled cell. We used 400nm (˜3 mW) to pump the B band and 800 nm (˜1 mW) to probe the III band. The III band corresponds to the charge-transfer transition between heme π and iron d orbital, and is assigned to the ground electronic state of the heme. Therefore this band can be used to probe the ground state population. Three separate dynamic components were observed: a very fast transient τ1 ˜ 200 fs; a several hundred femtosecond component (τ2); and a recovery of the ground state absorption(τ3). We find τ3 apparently decreases with decreasing hydration while τ1 and τ2 are independent of hydration.

  12. Sequence Polymorphism of Cytochrome b Gene in Theileria annulata Tunisian Isolates and Its Association with Buparvaquone Treatment Failure.

    Directory of Open Access Journals (Sweden)

    Moez Mhadhbi

    Full Text Available Buparvaquone (BW 720C is the major hydroxynaphtoquinone active against tropical theileriosis (Theileria annulata infection. Previous studies showed that buparvaquone, similarly to others hydroxynaphtoquinone, probably acts by binding to cytochrome b (cyt b inhibiting the electron transport chain in the parasite. Several observations suggested that T. annulata is becoming resistant to buparvaquone in many endemic regions (Tunisia, Turkey and Iran, which may hinder the development of bovine livestock in these areas.In the present study we sought to determine whether point mutations in T. annulata cytochrome b gene could be associated to buparvaquone resistance. A total of 28 clones were studied in this work, 19 of which were obtained from 3 resistant isolates (ST2/12, ST2/13 and ST2/19 collected at different time after treatment, from a field treatment failure and nine clones isolated from 4 sensitive stocks of T. annulata (Beja, Battan, Jed4 and Sousse. The cytochrome b gene was amplified and sequenced. We identified five point mutations at the protein sequences (114, 129, 253, 262 and 347 specific for the clones isolated from resistant stocks. Two of them affecting 68% (13/19 of resistant clones, are present in the drug-binding site Q02 region at the position 253 in three resistant clones and at the position 262 in 11 out of 19 resistant clones. These two mutations substitute a neutral and hydrophobic amino acids by polar and hydrophilic ones which could interfere with the drug binding capabilities. When we compared our sequences to the Iranian ones, the phylogenetic tree analyses show the presence of a geographical sub-structuring in the population of T. annulata.Taken together, our results suggest that the cytochrome b gene may be used as a tool to discriminate between different T. annulata genotypes and also as a genetic marker to characterize resistant isolates of T. annulata.

  13. Conformational changes of the NADPH-dependent cytochrome P450 reductase in the course of electron transfer to cytochromes P450

    DEFF Research Database (Denmark)

    Laursen, Tomas; Jensen, Kenneth; Møller, Birger Lindberg

    2011-01-01

    The NADPH-dependent cytochrome P450 reductase (CPR) is a key electron donor to eucaryotic cytochromes P450 (CYPs). CPR shuttles electrons from NADPH through the FAD and FMN-coenzymes into the iron of the prosthetic heme-group of the CYP. In the course of these electron transfer reactions, CPR...... to serve as an effective electron transferring "nano-machine"....

  14. Disruption of protein-protein interactions: design of a synthetic receptor that blocks the binding of cytochrome c to cytochrome c peroxidase.

    Science.gov (United States)

    Wei, Y; McLendon, G L; Hamilton, A D; Case, M A; Purring, C B; Lin, Q; Park, H S; Lee, C S; Yu, T

    2001-09-07

    Synthetic receptor 1 has been found via fluorescence titration to compete effectively with cytochrome c peroxidase for binding cytochrome c (Cc), forming 1:1 Cc:1 complex with a binding constant of (3 +/- 1) x 10(8) M-1, and to disrupt Cc: Apaf-1 complex, a key adduct in apoptosis.

  15. Uml2 is a novel CalB-type lipase of Ustilago maydis with phospholipase A activity.

    Science.gov (United States)

    Buerth, Christoph; Kovacic, Filip; Stock, Janpeter; Terfrüchte, Marius; Wilhelm, Susanne; Jaeger, Karl-Erich; Feldbrügge, Michael; Schipper, Kerstin; Ernst, Joachim F; Tielker, Denis

    2014-06-01

    CalB of Pseudozyma aphidis (formerly named Candida antarctica) is one of the most widely applied enzymes in industrial biocatalysis. Here, we describe a protein with 66 % sequence identity to CalB, designated Ustilago maydis lipase 2 (Uml2), which was identified as the product of gene um01422 of the corn smut fungus U. maydis. Sequence analysis of Uml2 revealed the presence of a typical lipase catalytic triad, Ser-His-Asp with Ser125 located in a Thr-Xaa-Ser-Xaa-Gly pentapeptide. Deletion of the uml2 gene in U. maydis diminished the ability of cells to hydrolyse fatty acids from tributyrin or Tween 20/80 substrates, thus demonstrating that Uml2 functions as a lipase that may contribute to nutrition of this fungal pathogen. Uml2 was heterologously produced in Pichia pastoris and recombinant N-glycosylated Uml2 protein was purified from the culture medium. Purified Uml2 released short- and long-chain fatty acids from p-nitrophenyl esters and Tween 20/80 substrates. Furthermore, phosphatidylcholine substrates containing long-chain saturated or unsaturated fatty acids were effectively hydrolysed. Both esterase and phospholipase A activity of Uml2 depended on the Ser125 catalytic residue. These results indicate that Uml2, in contrast to CalB, exhibits not only esterase and lipase activity but also phospholipase A activity. Thus, by genome mining, we identified a novel CalB-like lipase with different substrate specificities.

  16. Searching for links between magnetic fields and stellar evolution. I. A survey of magnetic fields in open cluster A- and B-type stars with FORS1

    CERN Document Server

    Bagnulo, S; Landstreet, J D; Mason, E; Silaj, J; Wade, G A

    2006-01-01

    About 5% of upper main sequence stars are permeated by a strong magnetic field, the origin of which is still matter of debate. With this work we provide observational material to study how magnetic fields change with the evolution of stars on the main sequence, and to constrain theory explaining the presence of magnetic fields in A and B-type stars. Using FORS1 in spectropolarimetric mode at the ESO VLT, we have carried out a survey of magnetic fields in early-type stars belonging to open clusters and associations of various ages. We have measured the magnetic field of 235 early-type stars with a typical uncertainty of about 100 G. In our sample, 97 stars are Ap or Bp stars. For these targets, the median error bar of our field measurements was about 80 G. A field has been detected in about 41 of these stars, 37 of which were not previously known as magnetic stars. For the 138 normal A and B-type stars, the median error bar was 136 G, and no field was detected in any of them.

  17. Heat resistant reduced activation 12% Cr steel of 16Cr12W2VTaB type-advanced structural material for fusion and fast breeder power reactors

    Science.gov (United States)

    Ioltukhovskiy, A. G.; Leonteva-Smirnova, M. V.; Solonin, M. I.; Chernov, V. M.; Golovanov, V. N.; Shamardin, V. K.; Bulanova, T. M.; Povstyanko, A. V.; Fedoseev, A. E.

    2002-12-01

    Heat resistant 12% Cr steels of the 16Cr12W2VTaB type (12Cr-2W-V-Ta-B-0.16C) provide a reduced activation material that can be used as a structural material for fusion and fast breeder reactors. The composition under study meets scientific and engineering requirements and has an optimal base element composition to provide a δ-ferrite content of no more than 20%. It also has a minimum quantity of low melting impurity elements and non-metallic inclusions. Short-term tensile properties for the steel tested to 700 °C are provided after the standard heat treatment (normalization, temper). Rupture strength and creep properties for the steel depending on the initial heat treatment conditions are also given. The microstructural stability of the 16Cr12W2VTaB type steel at temperatures up to 650 °C is predicted to be good, and the properties of the steel after irradiation in BOR-60 are demonstrated.

  18. Heat resistant reduced activation 12% Cr steel of 16Cr12W2VTaB type-advanced structural material for fusion and fast breeder power reactors

    Energy Technology Data Exchange (ETDEWEB)

    Ioltukhovskiy, A.G. E-mail: iral@bochvar.ru; Leonteva-Smirnova, M.V.; Solonin, M.I.; Chernov, V.M.; Golovanov, V.N.; Shamardin, V.K.; Bulanova, T.M.; Povstyanko, A.V.; Fedoseev, A.E

    2002-12-01

    Heat resistant 12% Cr steels of the 16Cr12W2VTaB type (12Cr-2W-V-Ta-B-0.16C) provide a reduced activation material that can be used as a structural material for fusion and fast breeder reactors. The composition under study meets scientific and engineering requirements and has an optimal base element composition to provide a {delta}-ferrite content of no more than 20%. It also has a minimum quantity of low melting impurity elements and non-metallic inclusions. Short-term tensile properties for the steel tested to 700 deg. C are provided after the standard heat treatment (normalization, temper). Rupture strength and creep properties for the steel depending on the initial heat treatment conditions are also given. The microstructural stability of the 16Cr12W2VTaB type steel at temperatures up to 650 deg. C is predicted to be good, and the properties of the steel after irradiation in BOR-60 are demonstrated.

  19. The chemical composition of the Orion star-forming region. III. C, N, Ne, Mg and Fe abundances in B-type stars revisited

    CERN Document Server

    Nieva, Maria-Fernanda

    2011-01-01

    Early B-type stars are invaluable indicators for elemental abundances of their birth environments. In contrast to the surrounding neutral interstellar matter (ISM) and HII regions their chemical composition is unaffected by depletion onto dust grains and by the derivation of different abundances from recombination and collisional lines. In combination with ISM or nebular gas-phase abundances they facilitate the dust-phase composition to be constrained. Precise abundances of C, N, Mg, Ne, Fe in early B-type stars in the Orion star-forming region are determined in order to: a) review previous determinations using a self-consistent quantitative spectral analysis based on modern stellar atmospheres and recently updated model atoms, b) complement results found in Paper I for oxygen and silicon, c) establish an accurate and reliable set of stellar metal abundances to constrain the dust-phase composition of the Orion HII region in Paper II of the series. A detailed, self-consistent spectroscopic study of a sample of...

  20. Subunit analysis of mitochondrial cytochrome c oxidase and cytochrome bc1 by reversed-phase high-performance liquid chromatography.

    Science.gov (United States)

    Kesa, Peter; Bhide, Mangesh; Lysakova, Veronika; Musatov, Andrey

    2017-01-01

    A rapid separation of the ten nuclearly-encoded subunits of mitochondrial cytochrome c oxidase, and ten out of the eleven subunits of cytochrome bc1, was achieved using a short, 50 mm C18-reversed-phase column. The short column decreased the elution time 4-7 fold while maintaining the same resolution quality. Elution was similar to a previously published protocol, i.e., a water/acetonitrile elution gradient containing trifluoroacetic acid. Isolated subunits were identified by MALDI-TOF. The rapidity of the described method makes it extremely useful for determining the subunit composition of isolated mitochondrial complexes. The method can be used for both analytical and micro-preparative purposes.

  1. Isolation and Characterization of a Hybrid Respiratory Supercomplex Consisting of Mycobacterium tuberculosis Cytochrome bcc and Mycobacterium smegmatis Cytochrome aa 3 *

    OpenAIRE

    Kim, Mi-Sun; Jang, Jichan; AB Rahman, Nurlilah Binte; Pethe, Kevin; Berry, Edward A.; Huang, Li-Shar

    2015-01-01

    Recently, energy production pathways have been shown to be viable antitubercular drug targets to combat multidrug-resistant tuberculosis and eliminate pathogen in the dormant state. One family of drugs currently under development, the imidazo[1,2-a]pyridine derivatives, is believed to target the pathogen's homolog of the mitochondrial bc 1 complex. This complex, denoted cytochrome bcc, is highly divergent from mitochondrial Complex III both in subunit structure and inhibitor sensitivity, maki...

  2. New Arabidopsis thaliana cytochrome c partners: a look into the elusive role of cytochrome c in programmed cell death in plants.

    Science.gov (United States)

    Martínez-Fábregas, Jonathan; Díaz-Moreno, Irene; González-Arzola, Katiuska; Janocha, Simon; Navarro, José A; Hervás, Manuel; Bernhardt, Rita; Díaz-Quintana, Antonio; De la Rosa, Miguel Á

    2013-12-01

    Programmed cell death is an event displayed by many different organisms along the evolutionary scale. In plants, programmed cell death is necessary for development and the hypersensitive response to stress or pathogenic infection. A common feature in programmed cell death across organisms is the translocation of cytochrome c from mitochondria to the cytosol. To better understand the role of cytochrome c in the onset of programmed cell death in plants, a proteomic approach was developed based on affinity chromatography and using Arabidopsis thaliana cytochrome c as bait. Using this approach, ten putative new cytochrome c partners were identified. Of these putative partners and as indicated by bimolecular fluorescence complementation, nine of them bind the heme protein in plant protoplasts and human cells as a heterologous system. The in vitro interaction between cytochrome c and such soluble cytochrome c-targets was further corroborated using surface plasmon resonance. Taken together, the results obtained in the study indicate that Arabidopsis thaliana cytochrome c interacts with several distinct proteins involved in protein folding, translational regulation, cell death, oxidative stress, DNA damage, energetic metabolism, and mRNA metabolism. Interestingly, some of these novel Arabidopsis thaliana cytochrome c-targets are closely related to those for Homo sapiens cytochrome c (Martínez-Fábregas et al., unpublished). These results indicate that the evolutionarily well-conserved cytosolic cytochrome c, appearing in organisms from plants to mammals, interacts with a wide range of targets on programmed cell death. The data have been deposited to the ProteomeXchange with identifier PXD000280.

  3. Non-Michaelis-Menten kinetics in cytochrome P450-catalyzed reactions.

    Science.gov (United States)

    Atkins, William M

    2005-01-01

    The cytochrome P450 monooxygenases (CYPs) are the dominant enzyme system responsible for xenobiotic detoxification and drug metabolism. Several CYP isoforms exhibit non-Michaelis-Menten, or "atypical," steady state kinetic patterns. The allosteric kinetics confound prediction of drug metabolism and drug-drug interactions, and they challenge the theoretical paradigms of allosterism. Both homotropic and heterotropic ligand effects are now widely documented. It is becoming apparent that multiple ligands can simultaneously bind within the active sites of individual CYPs, and the kinetic parameters change with ligand occupancy. In fact, the functional effect of any specific ligand as an activator or inhibitor can be substrate dependent. Divergent approaches, including kinetic modeling and X-ray crystallography, are providing new information about how multiple ligand binding yields complex CYP kinetics.

  4. First-principles molecular dynamics study of proton transfer mechanism in bovine cytochrome c oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Kamiya, Katsumasa [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Boero, Mauro [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Tateno, Masaru [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Shiraishi, Kenji [CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Oshiyama, Atsushi [Center for Computational Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

    2007-09-12

    Density functional based first-principles molecular dynamics calculations, performed on a model system extracted from the bovine cytochrome c oxidase, have been performed in an attempt to inspect the proton transfer mechanism across a peptide group. Our model system includes the specific Tyr440-Ser441 peptide group involved in a novel proton transfer path and shows that the Y440-S441 enol peptide group [-C(OH) = N-], which is a structural isomer of a keto form [-CO-NH-], is the product of the deprotonation of an imidic acid [-C(OH)-NH-] occurring in the vicinity of the deprotonated aspartic acid residue. For the subsequent enol-to-keto tautomerization, a direct H{sup +} transfer path in the Y440-S441 peptide group has been identified, in which the transition state takes a distorted four-membered ring structure.

  5. Cytochrome c location in phosphatidylcholine/cardiolipin model membranes: resonance energy transfer study.

    Science.gov (United States)

    Gorbenko, Galina P; Domanov, Yegor A

    2003-03-25

    Resonance energy transfer between lipid-bound fluorescent probe 3-methoxybenzanthrone as a donor and heme group of cytochrome c as an acceptor has been examined to ascertain the protein disposition relative to the surface of model membranes composed of phosphatidylcholine and cardiolipin (10, 50 and 80 mol%). The model of energy transfer in membrane systems has been extended to the case of donors distributed between the two-bilayer leaflets and acceptors located at the outer monolayer taking into account the donor and acceptor orientational behavior. Assuming specific protein orientation relative to the membrane surface and varying lateral distance of the donor-acceptor closest approach in the range from 0 to 3.5 nm the limits for possible heme distances from the bilayer midplane have been found to be 0.8-3 nm (10 mol% CL), 0-2.6 nm (50 mol% CL), and 1.4-3.3 nm (80 mol% CL).

  6. In vivo cytochrome P450 drug metabolizing enzyme characterization using surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Li, Yanfang; Bachmann, Kenneth A.; Cameron, Brent D.

    2003-07-01

    The development of a rapid, inexpensive, and accurate in vivo phenotyping methodology for characterizing drug-metabolizing phenotypes with reference to the cytochrome P450 (CYP450) enzymes would be very beneficial. In terms of application, in the wake of the human genome project, considerable interest is focused on the development of new drugs whose uses will be tailored to specific genetic polymorphisms, and on the individualization of dosing regimens that are also tailored to meet individual patient needs depending upon genotype. In this investigation, chemical probes for CYP450 enzymes were characterized and identified with Raman spectroscopy. Furthermore, gold-based metal colloid clusters were utilized to generate surface enhanced Raman spectra for each of the chemical probes. Results will be presented demonstrating the ability of SERS to identify minute quantities of these probes on the order needed for in vivo application.

  7. Cox26 is a novel stoichiometric subunit of the yeast cytochrome c oxidase.

    Science.gov (United States)

    Levchenko, Maria; Wuttke, Jan-Moritz; Römpler, Katharina; Schmidt, Bernhard; Neifer, Klaus; Juris, Lisa; Wissel, Mirjam; Rehling, Peter; Deckers, Markus

    2016-07-01

    The cytochrome c oxidase (COX) is the terminal enzyme of the respiratory chain. The complex accepts electrons from cytochrome c and passes them onto molecular oxygen. This process contributes to energy capture in the form of a membrane potential across the inner membrane. The enzyme complex assembles in a stepwise process from the three mitochondria-encoded core subunits Cox1, Cox2 and Cox3, which associate with nuclear-encoded subunits and cofactors. In the yeast Saccharomyces cerevisiae, the cytochrome c oxidase associates with the bc1-complex into supercomplexes, allowing efficient energy transduction. Here we report on Cox26 as a protein found in respiratory chain supercomplexes containing cytochrome c oxidase. Our analyses reveal Cox26 as a novel stoichiometric structural subunit of the cytochrome c oxidase. A loss of Cox26 affects cytochrome c oxidase activity and respirasome organization.

  8. Cytochrome c binding to Apaf-1: The effects of dATP and ionic strength

    Science.gov (United States)

    Purring-Koch, Cherie; McLendon, George

    2000-01-01

    In the apoptosis pathway in mammals, cytochrome c and dATP are critical cofactors in the activation of caspase 9 by Apaf-1. Until now, the detailed sequence of events in which these cofactors interact has been unclear. Here, we show through fluorescence polarization experiments that cytochrome c can bind to Apaf-1 in the absence of dATP; when dATP is added to the cytochrome c·Apaf-1 complex, further assembly occurs to produce the apoptosome. These findings, along with the discovery that the exposed heme edge of cytochrome c is involved in the cytochrome c·Apaf-1 interaction, are confirmed through enhanced chemiluminescence visualization of native PAGE gels and through acrylamide fluorescence quenching experiments. We also report here that the cytochrome c·Apaf-1 interaction depends highly on ionic strength, indicating that there is a strong electrostatic interaction between the two proteins. PMID:11035811

  9. Species identification of Asini Corii Collas (donkey glue) by PCR amplification of cytochrome b gene.

    Science.gov (United States)

    Kumeta, Yukie; Maruyama, Takuro; Asama, Hiroshi; Yamamoto, Yutaka; Hakamatsuka, Takashi; Goda, Yukihiro

    2014-01-01

    Asini Corii Collas (ACC; donkey glue) is a crude drug used to promote hematopoiesis and arrest bleeding. Because adulteration of the drug with substances from other animals such as horses, cattle, and pigs has been found, we examined PCR methods based on the sequence of the cytochrome b gene for source species identification. Two strategies for extracting DNA from ACC were compared, and the ion-exchange resin procedure was revealed to be more suitable than the silica-based one. Using DNA extracted from ACC by the ion-exchange resin procedure, PCR methods for species-specific detection of donkey, horse, cattle, and pig substances were established. When these species-specific PCR methods were applied to ACC, amplicons were obtained only by the donkey-specific PCR. Cattle-specific PCR detected as little as 0.1% admixture of cattle glue in the ACC. These results suggest that the species-specific PCR methods established in this study would be useful for simple and easy detection of adulteration of ACC.

  10. Virtual Screening and Prediction of Site of Metabolism for Cytochrome P450 1A2 Ligands

    DEFF Research Database (Denmark)

    Vasanthanathan, P.; Hritz, Jozef; Taboureau, Olivier

    2009-01-01

    With the availability of an increasing number of high resolution 3D structures of human cytochrome P450 enzymes, structure-based modeling tools are more readily used. In this study we explore the possibilities of using docking and scoring experiments on cytochrome P450 1A2. Three different...... and earlier classification data using machine learning methods. The possibilities and limitations of using structure-based drug design tools for cytochrome P450 1A2 come to light and are discussed....

  11. Structural insights into electron transfer in caa 3-type cytochrome oxidase

    OpenAIRE

    Lyons, Joseph A.; Aragão, David; Slattery, Orla; Pisliakov, Andrei V.; Soulimane, Tewfik; Caffrey, Martin

    2012-01-01

    Summary Paragraph Cytochrome c oxidase is a member of the heme copper oxidase superfamily (HCO) 1 . HCOs function as the terminal enzymes in the respiratory chain of mitochondria and aerobic prokaryotes, coupling molecular oxygen reduction to transmembrane proton pumping. Integral to the enzyme’s function is the transfer of electrons from cytochrome c to the oxidase via a transient association of the two proteins. Electron entry and exit are proposed to occur from the same site on cytochrome ...

  12. Binding of benzo(a)pyrene to DNA by cytochrome P-450 catalyzed one-electron oxidation in rat liver microsomes and nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cavalieri, E.L.; Rogan, E.G.; Devanesan, P.D.; Cremonesi, P. (Univ. of Nebraska Medical Center, Omaha (USA)); Cerny, R.L.; Gross, M.L. (Univ. of Nebraska, Lincoln (USA)); Bodell, W.J. (Univ. of California, San Francisco (USA))

    1990-05-22

    To investigate whether cytochrome P-450 catalyzes the covalent binding of substrates to DNA by one-electron oxidation, the ability of both uninduced and 3-methylcholanthrene (MC) induced rat liver microsomes and nuclei to catalyze covalent binding of benzo(a)pyrene (BP) to DNA and formation of the labile adduct 7-(benzo(a)pyren-6-yl)guanine (BP-N7Gua) was investigated. In the various systems studied, 1-9 times more BP-N7Gua adduct was isolated than the total amount of stable BP adducts in the DNA. The specific cytochrome P-450 inhibitor 2-((4,6-dichloro-o-biphenyl)oxy)ethylamine hydrobromide (DPEA) reduced or eliminated BP metabolism, binding of BP to DNA, and formation of BP-N7Gua by cytochrome P-450 in both microsomes and nuclei. The effects of the antioxidants cysteine, glutathione, and p-methoxythiophenol were also investigated. This study represents the first demonstration of cytochrome P-450 mediating covalent binding of substrates to DNA via one-electron oxidation and suggests that this enzyme can catalyze peroxidase-type electron-transfer reactions.

  13. Activation of the human neutrophil NADPH oxidase results in coupling of electron carrier function between ubiquinone-10 and cytochrome b559.

    Science.gov (United States)

    Gabig, T G; Lefker, B A

    1985-04-10

    The enzymatic activity underlying the respiratory burst in human neutrophils was examined in a subcellular fraction with high specific activity and shown to be a membrane-associated complex of a flavoprotein, ubiquinone-10, and cytochrome b559 in an approximate 1.3:1:2 molar ratio. Study of the redox poise of these electron carriers indicated that electron flow in the intact complex from unstimulated cells proceeded: NADPH----E-FAD----ubiquinone-10. Similar studies on the complex prepared from stimulated neutrophils indicated that electron flow proceeded: NADPH----E-FAD----ubiquinone-10----cytochrome b559----oxygen. The active enzyme complex was inhibited by p-chloromercuribenzoate. Inhibition persisted after removal of excess inhibitor, was reversed by dithiothreitol, and could be blocked by prior addition of substrate (NADPH). Inhibition of the active oxidase complex by p-chloromercuribenzoate also inhibited electron flow from NADPH to all purported electron carriers in the chain (i.e. E-FAD, ubiquinone-10, and cytochrome b559). We conclude that activation of the oxidase enzyme complex in the intact neutrophil resulted in linkage of electron carrier function between endogenous ubiquinone-10 and cytochrome b559 and was without demonstrable effect on proximal electron flow. The p-chloromercuribenzoate sensitive site(s) proximal to the initial electron acceptor (E-FAD) did not appear to be altered by the cellular activation process.

  14. Scavenger receptor class B type I (SR-BI) in pig enterocytes: trafficking from the brush border to lipid droplets during fat absorption

    DEFF Research Database (Denmark)

    Hansen, Gert Helge; Niels-Christiansen, Lise-Lotte W; Immerdal, Lissi

    2003-01-01

    BACKGROUND: Scavenger receptor class B type I (SR-BI) is known to mediate cellular uptake of cholesterol from high density lipoprotein particles and is particularly abundant in liver and steroidogenic tissues. In addition, SR-BI expression in the enterocyte brush border has also been reported...... but its role in the small intestine remains unclear. AIM AND METHODS: To gain insight into the possible function of pig SR-BI during uptake of dietary fat, its localisation in enterocytes was studied in the fasting state and during fat absorption by immunogold electron microscopy and subcellular...... fat, SR-BI is endocytosed from the enterocyte brush border and accumulates in cytoplasmic lipid droplets. Internalisation of the receptor occurs mainly by clathrin coated pits rather than by a caveolae/lipid raft based mechanism....

  15. The A- and B-type muscarinic acetylcholine receptors from Drosophila melanogaster couple to different second messenger pathways

    DEFF Research Database (Denmark)

    Ren, Guilin Robin; Folke, Jonas; Hauser, Frank

    2015-01-01

    Muscarinic acetylcholine receptors (mAChRs) are G protein-coupled receptors (GPCRs) that are activated by the agonists acetylcholine and muscarine and blocked by several antagonists, among them atropine. In mammals five mAChRs (m1-m5) exist of which m1, m3, and m5 are coupled to members of the Gq...... to classical antagonists such as atropine. Here, we find that the D. melanogaster A-type mAChR is coupled to Gq/11 and D. melanogaster B-type mAChR to Gi/0. Furthermore, by comparing the second and third intracellular loops of all animal mAChRs for which the G protein coupling has been established, we could...

  16. Higher Serum Concentrations of N-Terminal Pro-B-Type Natriuretic Peptide Associate with Prevalent Hypertension whereas Lower Associate with Incident Hypertension

    DEFF Research Database (Denmark)

    Seven, Ekim; Husemoen, Lise L N; Ibsen, Hans

    2015-01-01

    BACKGROUND: The role of the natriuretic peptides (NPs) in hypertension is complex. Thus, a higher blood NP concentration is a robust marker of pressure-induced cardiac damage in patients with hypertension, whereas genetically elevated NP concentrations are associated with a reduced risk...... of hypertension and overweight individuals presumably at high risk of hypertension have lower NP concentrations. OBJECTIVE: To investigate the associations between serum N-terminal pro-B-type natriuretic peptide (NT-proBNP), used as a surrogate marker for active BNP, and prevalent as well as 5-year incident...... and baseline blood pressure (only incident model), one standard deviation increase in baseline log-transformed NT-proBNP concentrations was on one side associated with a 21% higher risk of PHT (odds ratio [OR]: 1.21 [95% confidence interval (CI): 1.13-1.30], P

  17. Amino-terminal pro-B-type natriuretic peptide testing to assist the diagnostic evaluation of heart failure in symptomatic primary care patients

    DEFF Research Database (Denmark)

    Hildebrandt, P.; Collinson, P.O.

    2008-01-01

    When used for the evaluation of symptomatic patients in general practice, amino-terminal pro-B-type natriuretic peptide (NT-proBNP) testing is highly sensitive, with an excellent negative predictive value for cost-effective exclusion of the diagnosis of heart failure (HF). Importantly (similar...... to other NP assays), lower values for NT-proBNP are expected among patients with HF in the primary care setting compared with patients with acute dyspnea. Among primary care patients with dyspnea, a noncardiac source of dyspnea is most likely in patients with findings below the recommended age......-stratified NT-proBNP cut points. Conversely, an NT-proBNP result above the age-stratified primary care cut points does not absolutely indicate the presence of HF; a more directed cardiovascular workup is indicated Udgivelsesdato: 2008/2/4...

  18. Influence of operation factors on brittle fracture initiation and critical local normal stress in SE(B) type specimens of VVER reactor pressure vessel steels

    Science.gov (United States)

    Kuleshova, E. A.; Erak, A. D.; Kiselev, A. S.; Bubyakin, S. A.; Bandura, A. P.

    2015-12-01

    A complex of mechanical tests and fractographic studies of VVER-1000 RPV SE(B) type surveillance specimens was carried out: the brittle fracture origins were revealed (non-metallic inclusions and structural boundaries) and the correlation between fracture toughness parameters (CTOD) and fracture surface parameters (CID) was established. A computational and experimental method of the critical local normal stress determination for different origin types was developed. The values of the critical local normal stress for the structural boundary origin type both for base and weld metal after thermal exposure and neutron irradiation are lower than that for initial state due to the lower cohesive strength of grain boundaries as a result of phosphorus segregation.

  19. The Utility of B-type Natriuretic Peptide to Predict Prognosis of Acute Myocardial Infarction Patients Complicated With Cardiogenic Shock Treated With Intra-aortic Ballon Counterpulsation

    Institute of Scientific and Technical Information of China (English)

    Jiang Xie; Xian Wang; Chen Tan

    2008-01-01

    Objectives To assess the prognostic value of B-type natriuretic peptide (BNP) in severe AMI patients treated with intra-aortic ballon counterpulsation(IABP).Methods A total of 42 AMI patients with cardiogenic shock were retrospectively studied.BNP plasma level was recorded in the 24th hour and 4th day after myocardial infarction.The different mortality were compared among patients with different BNP levels.Results With aggressive treatment,20 patients survived short term hospitalization.Plasma concentration of BNP in dying patients is much higher than in survivals (1369±353 vs 651±302 pg/ml.P<0.01).Patients with BNP higher than 1474 pg/mL had a mortality of 92.9%.Conclusions Elevated BNP level in AMI patients with cardiogenic shock treated with IABP is highly associated with poor prognosis.

  20. Kinetic modelling of cytochrome c adsorption on SBA-15.

    Science.gov (United States)

    Yokogawa, Yoshiyuki; Yamauchi, Rie; Saito, Akira; Yamato, Yuta; Toma, Takeshi

    2017-01-01

    The adsorption capacity of mesoporous silicate (MPS) materials as an adsorbent for protein adsorption from the aqueous phase and the mechanism of the adsorption processes by comparative analyses of the applicability of five kinetic transfer models, pseudo-first-order model, pseudo-second-order model, Elovich kinetic model, Bangham's equation model, and intraparticle diffusion model, were investigated. A mixture of tetraethyl orthosilicate (TEOS) and triblock copolymer as a template was stirred, hydrothermally treated to form the mesoporous SBA-15 structure, and heat-treated at 550°C to form the MPS material, SBA-15. The synthesized SBA-15 was immersed in a phosphate buffered saline (PBS) solution containing cytochrome c for 2, 48, and 120 hours at 4°C. The TEM observations of proteins on/in mesoporous SBA-15 revealed the protein behaviors. The holes of the MPS materials were observed to overlap those of the stained proteins for the first 2 hours of immersion. The stained proteins were observed between primary particles and partly inside the mesoporous channels in the MPS material when it had been immersed for 48 hours. For MPS when it had been immersed for 120 hours, stained proteins were observed in almost all meso-scale channels of MPS. The time profiles for adsorption of proteins can be described well by Bangham's equation model and the intraparticle diffusion model. The Bangham's equation model is based on the assumption that pore diffusion was the only rate controlling step during adsorption, whose contribution to the overall mechanism of cytochrome c adsorption on SBA-15 should not be neglected. The kinetic curves obtained from the experiment for cytochrome c adsorption on SBA-15 could show the three steps: the initial rapid increase of the adsorbed amount of cytochrome c, the second gradual increase, and the final equilibrium stage. These three adsorption steps can be interpreted well by the multi-linearity of the intraparticle diffusion model

  1. Cumene hydroperoxide effected hydroperoxidation by cytochrome P-450.

    Science.gov (United States)

    Chen, C; Gurka, D P

    1985-04-01

    9-Methylfluorene was found to be oxygenated to 9-hydroperoxy-9-methylfluorene and 9-hydroxy-9-methylfluorene by cytochrome P-450 in the presence of cumene hydroperoxide. Molecular oxygen is required and carbon monoxide is inhibitory. The reaction is inhibited by SKF-525A and metyrapone. Metyrapone and cumene hydroperoxide also retard the conversion of 9-hydroperoxy-9-methylfluorene to 9-hydroxy-9-methylfluorene. The reaction is different from hydroperoxide-supported oxygenation, since the cumene hydroperoxide appears to act as an effector of the enzyme rather than oxygen donor. It is suggested that substrates with stable radicals can be dioxygenated in this manner.

  2. A Conserved Steroid Binding Site in Cytochrome c Oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Ling; Mills, Denise A.; Buhrow, Leann; Hiser, Carrie; Ferguson-Miller, Shelagh (Michigan)

    2010-09-02

    Micromolar concentrations of the bile salt deoxycholate are shown to rescue the activity of an inactive mutant, E101A, in the K proton pathway of Rhodobacter sphaeroides cytochrome c oxidase. A crystal structure of the wild-type enzyme reveals, as predicted, deoxycholate bound with its carboxyl group at the entrance of the K path. Since cholate is a known potent inhibitor of bovine oxidase and is seen in a similar position in the bovine structure, the crystallographically defined, conserved steroid binding site could reveal a regulatory site for steroids or structurally related molecules that act on the essential K proton path.

  3. Effects of methotrexate on rat P-450 cytochrome mono-oxygenases; Action du methotrexate sur les monooxygenases a cytochromes P-450 chez le rat

    Energy Technology Data Exchange (ETDEWEB)

    Guitton, J.; Guilluy, R.; Brazier, J.L. [Faculte de Pharmacie, 69 - Lyon (France); Souillet, G. [Hopital Debrousse, 69 - Lyon (France); Riviere, J.L. [INRA, 69 - Marcy l`Etoile (France); Gerard, F. [Institut Pasteur, 69 - Lyon (France)

    1994-12-31

    Methotrexate, an anti-cancerous agent, acts as an anti-metabolite of the nucleic acids which synthesis is then inhibited. Using aminopyrine breath test after methotrexate processing, the effects of the molecule on activities of the hepatocyte P-450 cytochrome mono-oxygenases, are studied. Breath micro-tests with carbon 13-labelled aminopyrine have been carried out to observe the metabolism evolution. Micro-test results have been compared to microsomal enzymatic activities for various substrates, and also to P-450 cytochrome ratio. Results show that methotrexate induces a reduction in the P-450 cytochrome ratio, and thus reduce the hepatic biotransformation process. 1 fig., 30 refs.

  4. Viability of cytochrome c genotypes depends on cytoplasmic backgrounds in Tigriopus californicus.

    Science.gov (United States)

    Willett, C S; Burton, R S

    2001-08-01

    Because of their extensive functional interaction, mitochondrial DNA (mtDNA) and nuclear genes may evolve to form coadapted complexes within reproductively isolated populations. As a consequence of coadaptation, the fitness of particular nuclear alleles may depend on mtDNA genotype. Among populations of the copepod Tigriopus californicus, there are high levels of amino acid substitutions in both the mtDNA genes encoding subunits of cytochrome c oxidase (COX) and the nuclear gene encoding cytochrome c (CYC), the substrate for COX. Because of the functional interaction between enzyme and substrate proteins, we hypothesized that the fitness of CYC genotypes would depend on mtDNA genotype. To test this hypothesis, segregation ratios for CYC and a second nuclear marker (histone H1) unrelated to mitochondrial function were scored in F2 progeny of several reciprocal interpopulation crosses. Genotypic ratios at the CYC locus (but not the H1 locus) differed between reciprocal crosses and differed from expected Mendelian ratios, suggesting that CYC genotypic fitnesses were strongly influenced by cytoplasmic (including mtDNA) background. However, in most cases the nature of the deviations from Mendelian ratios and differences between reciprocal crosses are not consistent with simple coevolution between CYC and mtDNA background. In a cross in which both newly hatched larvae and adults were sampled, only the adult sample showed deviations from Mendelian ratios, indicating that genotypic viabilities differed. In two of six crosses, large genotypic ratio differences for CYC were observed between the sexes. These results suggest that significant variation in nuclear-mtDNA coadaptation may exist between T. californicus populations and that the relative viability of specific cytonuclear allelic combinations is somehow affected by sex.

  5. Identification of Small Molecule Inhibitors of Human Cytochrome c Oxidase That Target Chemoresistant Glioma Cells.

    Science.gov (United States)

    Oliva, Claudia R; Markert, Tahireh; Ross, Larry J; White, E Lucile; Rasmussen, Lynn; Zhang, Wei; Everts, Maaike; Moellering, Douglas R; Bailey, Shannon M; Suto, Mark J; Griguer, Corinne E

    2016-11-11

    The enzyme cytochrome c oxidase (CcO) or complex IV (EC 1.9.3.1) is a large transmembrane protein complex that serves as the last enzyme in the respiratory electron transport chain of eukaryotic mitochondria. CcO promotes the switch from glycolytic to oxidative phosphorylation (OXPHOS) metabolism and has been associated with increased self-renewal characteristics in gliomas. Increased CcO activity in tumors has been associated with tumor progression after chemotherapy failure, and patients with primary glioblastoma multiforme and high tumor CcO activity have worse clinical outcomes than those with low tumor CcO activity. Therefore, CcO is an attractive target for cancer therapy. We report here the characterization of a CcO inhibitor (ADDA 5) that was identified using a high throughput screening paradigm. ADDA 5 demonstrated specificity for CcO, with no inhibition of other mitochondrial complexes or other relevant enzymes, and biochemical characterization showed that this compound is a non-competitive inhibitor of cytochrome c When tested in cellular assays, ADDA 5 dose-dependently inhibited the proliferation of chemosensitive and chemoresistant glioma cells but did not display toxicity against non-cancer cells. Furthermore, treatment with ADDA 5 led to significant inhibition of tumor growth in flank xenograft mouse models. Importantly, ADDA 5 inhibited CcO activity and blocked cell proliferation and neurosphere formation in cultures of glioma stem cells, the cells implicated in tumor recurrence and resistance to therapy in patients with glioblastoma. In summary, we have identified ADDA 5 as a lead CcO inhibitor for further optimization as a novel approach for the treatment of glioblastoma and related cancers.

  6. Cytochrome P450BM-3 reduces aldehydes to alcohols through a direct hydride transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kaspera, Ruediger; Sahele, Tariku; Lakatos, Kyle [Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195-7610 (United States); Totah, Rheem A., E-mail: rtotah@u.washington.edu [Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195-7610 (United States)

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer Cytochrome P450BM-3 reduced aldehydes to alcohols efficiently (k{sub cat} {approx} 25 min{sup -1}). Black-Right-Pointing-Pointer Reduction is a direct hydride transfer from R-NADP{sup 2}H to the carbonyl moiety. Black-Right-Pointing-Pointer P450 domain variants enhance reduction through potential allosteric/redox interactions. Black-Right-Pointing-Pointer Novel reaction will have implications for metabolism of xenobiotics. -- Abstract: Cytochrome P450BM-3 catalyzed the reduction of lipophilic aldehydes to alcohols efficiently. A k{sub cat} of {approx}25 min{sup -1} was obtained for the reduction of methoxy benzaldehyde with wild type P450BM-3 protein which was higher than in the isolated reductase domain (BMR) alone and increased in specific P450-domain variants. The reduction was caused by a direct hydride transfer from preferentially R-NADP{sup 2}H to the carbonyl moiety of the substrate. Weak substrate-P450-binding of the aldehyde, turnover with the reductase domain alone, a deuterium incorporation in the product from NADP{sup 2}H but not D{sub 2}O, and no inhibition by imidazole suggests the reductase domain of P450BM-3 as the potential catalytic site. However, increased aldehyde reduction by P450 domain variants (P450BM-3 F87A T268A) may involve allosteric or redox mechanistic interactions between heme and reductase domains. This is a novel reduction of aldehydes by P450BM-3 involving a direct hydride transfer and could have implications for the metabolism of endogenous substrates or xenobiotics.

  7. [Cytochrome P450 enzymes and their role in drug interactions].

    Science.gov (United States)

    Papp-Jámbor, C; Jaschinski, U; Forst, H

    2002-01-01

    One of the factors that can alter the response to drugs is the concurrent administration of other drugs. There are several mechanisms by which drugs may interact, but most can be categorised as pharmacokinetic (absorption, distribution, metabolism, excretion), pharmacodynamic, or combined toxicity. Knowledge of the mechanism by which a given drug interaction occurs is often clinically useful and may help to avoid serious adverse events and perioperative morbidity. Although every tissue has some ability to metabolise drugs, the liver is the principal organ of drug metabolism and at the subcellular level the cytochrome P450 enzyme system is the main source of drug interaction. This article reviews the basic principles of drug metabolism and the role of cytochrome P450 in this scenario. Drugs frequently used in anaesthesia and critical care medicine such as benzodiazepines, opioid analgesics, antihypertensive and antiarrhythmic agents, antibiotics and antifungal drugs, antiemetics, histamine-receptor-antagonists, theopylline and paracetamol will be considered. The development of methods and tools which are practical and also economic, are of utmost importance since drug interaction is predictable if the metabolic pathway and the activity (genetic polymorphism) of the enzyme is known.

  8. Cytochrome P450 structure, function and clinical significance: A review.

    Science.gov (United States)

    Palrasu, Manikandan; Nagini, Siddavaram

    2017-01-25

    The cytochrome P450 (CYP) enzymes are membrane-bound hemoproteins that play a pivotal role in the detoxification of xenobiotics, cellular metabolism and homeostasis. Induction or inhibition of CYP enzymes is a major mechanism that underlies drug-drug interactions. CYP enzymes can be transcriptionally activated by various xenobiotics and endogenous substrates through receptor-dependent mechanisms. CYP enzyme inhibition is a principal mechanism for metabolism-based drug-drug interactions. Many chemotherapeutic drugs can cause drug interactions due to their ability to either inhibit or induce the CYP enzyme system. Predictions based on in silico analyses followed by validation have identified several microRNAs that regulate CYPs. Genetic polymorphisms and epigenetic changes in CYP genes may be responsible for inter-individual and inter-ethnic variations in disease susceptibility and the therapeutic efficacy of drugs. Knowledge about the substrates, inducers, inhibitors of CYP isoforms, and the polymorphisms of CYP enzymes may be used as an aid by clinicians to determine therapeutic strategy, and treatment doses for drugs that are metabolized by CYP gene products. The present review is a comprehensive compilation of cytochrome P450 structure, function, pharmacogenetics, and pharmacoepigenetics and clinical significance.

  9. The role of aspartate-235 in the binding of cations to an artificial cavity at the radical site of cytochrome c peroxidase.

    OpenAIRE

    Fitzgerald, M. M.; Trester, M. L.; Jensen, G M; McRee, D. E.; Goodin, D B

    1995-01-01

    The activated state of cytochrome c peroxidase, compound ES, contains a cation radical on the Trp-191 side chain. We recently reported that replacing this tryptophan with glycine creates a buried cavity at the active site that contains ordered solvent and that will specifically bind substituted imidazoles in their protonated cationic forms (Fitzgerald MM, Churchill MJ, McRee DE, Goodin DB, 1994, Biochemistry 33:3807-3818). Proposals that a nearby carboxylate, Asp-235, and competing monovalent...

  10. Cytochromes c550, c552, and c1 in the Electron Transport Network of Paracoccus denitrificans: Redundant or Subtly Different in Function?

    OpenAIRE

    Otten, M.F.; Oost, van der, J.; Reijnders, W. N. M.; Westerhoff, H.V.; Ludwig, B.; Spanning, van, R.J.M.

    2001-01-01

    Paracoccus denitrificans strains with mutations in the genes encoding the cytochrome c550, c552, or c1 and in combinations of these genes were constructed, and their growth characteristics were determined. Each mutant was able to grow heterotrophically with succinate as the carbon and free-energy source, although their specific growth rates and maximum cell numbers fell variably behind those of the wild type. Maximum cell numbers and rates of growth were also reduced when these strains were g...

  11. Present-day cosmic abundances. A comprehensive study of nearby early B-type stars and implications for stellar and Galactic evolution and interstellar dust models

    Science.gov (United States)

    Nieva, M.-F.; Przybilla, N.

    2012-03-01

    Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstellar medium (ISM) or H ii regions. Aims: A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Quantitative spectroscopy is used to characterise their atmospheric properties in a self-consistent way. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established. Methods: High-resolution and high-S/N FOCES, FEROS and ELODIE spectra of well-studied sharp-lined early B-type stars are analysed in non-LTE. Line-profile fits based on extensive model grids and an iterative analysis methodology are used to constrain stellar parameters and elemental abundances at high accuracy and precision. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equilibria and the Stark-broadened hydrogen Balmer lines, and they are confirmed by reproduction of the stars' global spectral energy distributions. Results: Effective temperatures are constrained to 1-2% and surface gravities to less than 15% uncertainty, along with accurate rotational, micro- and macroturbulence velocities. Good agreement of the resulting spectroscopic parallaxes with those from the new reduction of the Hipparcos catalogue is obtained. Absolute values for abundances of He, C, N, O, Ne, Mg, Si and Fe are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spectral range. Three sample stars, γ Ori, o Per and θ1 Ori D, are

  12. Microsomal cytochrome P450-3A4 (CYP3A4) nanobiosensor for the determination of 2,4-dichlorophenol-An endocrine disruptor compound

    Energy Technology Data Exchange (ETDEWEB)

    Hendricks, Nicolette R.; Waryo, Tesfaye T.; Arotiba, Omotayo; Jahed, Nazeem; Baker, Priscilla G.L. [SensorLab, Department of Chemistry, University of Western Cape, Moderddam Road, Bellville, Cape Town 7535 (South Africa); Iwuoha, Emmanuel I. [SensorLab, Department of Chemistry, University of Western Cape, Moderddam Road, Bellville, Cape Town 7535 (South Africa)], E-mail: eiwuoha@uwc.ac.za

    2009-02-28

    Cytochrome P450-3A4 (CYP3A4) is a monooxygenase enzyme that plays a major role in the detoxification of bioactive compounds and hydrophobic xenobiotics (e.g. medicines, drugs, environmental pollutants, food supplements and steroids). Physiologically the monooxygenation reactions of this class II, microsomal, b-type heme enzyme, usually requires cytochrome P450 reductase, NADPH. A novel CYP3A4 biosensor system that essentially simplified the enzymatic redox processes by allowing electron transfer between the electrode and the enzyme redox centre to occur, without any need for the physiological redox partners, was developed for the detection of 2,4-dichlorophenol (2,4-DCP), a priority environmental pollutant and an endocrine disruptor. The biosensor, GC/Naf-Co(Sep){sup 3+}/CYP3A4/Naf, was constructed by encapsulating CYP3A4 in a Nafion-cobalt (III) sepulchrate (Naf-Co(Sep){sup 3+}) composite film on a glassy carbon (GC) electrode. The responses of the biosensor to 2,4-dichlorophenol, erythromycin (CYP3A4 native substrate) and ketoconazole (CYP 3A4 natural inhibitor) were studied by cyclic and square wave voltammetric techniques. The detection limit (DL) of the biosensor for 2,4-dichlorophenol was 0.043 {mu}g L{sup -1}, which is by an order of magnitude lower than the EU limit (0.3 {mu}g L{sup -1}) for any pesticide compound in ground water. The biosensor's DL is lower than the U.S. Environmental Protection Agency's drinking water equivalent level (DWEL) value for 2,4-DCP, which is 2 {mu}g L{sup -1}.

  13. Theoretical study of the cytochrome P450 mediated metabolism of phosphorodithioate pesticides

    DEFF Research Database (Denmark)

    Rydberg, Patrik

    2012-01-01

    The toxicity of phosphorodithioate pesticides is due to the formation of the active oxane product through desulfurization by cytochrome P450 enzymes, both in humans and insects. During this desulfurization, inhibition of cytochrome P450 and a loss of heme has been observed. Here, we study...

  14. Acute hypoxia and cytochrome P450-mediated hepatic drug metabolism in humans

    DEFF Research Database (Denmark)

    Jürgens, Gesche; Christensen, Hanne Rolighed; Brøsen, Kim;

    2002-01-01

    Our objective was to investigate the effect of acute hypoxia on the activity of hepatic cytochrome P450 (CYP) enzymes.......Our objective was to investigate the effect of acute hypoxia on the activity of hepatic cytochrome P450 (CYP) enzymes....

  15. On the role of phospholipids in the cytochrome P450 enzyme system.

    NARCIS (Netherlands)

    Balvers, W.G.

    1994-01-01

    The cytochrome P450 enzyme system is involved in the metabolism and elimination of an almost unlimited number of endogenous and exogenous substrates. Biotransformation by cytochromes P450 plays a role in the conversion xenobiotics into more hydrophilic products. Generally, this process of biotransfo

  16. Electrochemical determination of hydrogen peroxide using Rhodobacter capsulatus cytochrome c peroxidase at a gold electrode

    NARCIS (Netherlands)

    De Wael, K.; Buschop, H.; Heering, H.A.; De Smet, L.; Van Beeumen, J.; Devreese, B.; Adriaens, A.

    2007-01-01

    We describe the redox behaviour of horse heart cytochrome c (HHC) and Rhodobacter capsulatus cytochrome c peroxidase (RcCCP) at a gold electrode modified with 4,4′-bipyridyl. RcCCP shows no additional oxidation or reduction peaks compared to the electrochemistry of only HHC, which indicates that it

  17. Regulation of expression of the Aspergillus niger benzoate para-hydroxylase cytochrome P450 system

    NARCIS (Netherlands)

    Brink, J.M. van den; Punt, P.J.; Gorcom, R.F.M. van; Hondel, C.A.M.J.J. van den

    2000-01-01

    Cytochrome P450 enzyme systems are found throughout nature and are involved in many different, often complex, bioconversions. In the endoplasmic reticulum of the filamentous fungus Aspergillus niger a cytochrome P450 enzyme system is present that is capable of the para-hydroxylation of benzoate. The

  18. Subunit II of Bacillus subtilis cytochrome c oxidase is a lipoprotein

    NARCIS (Netherlands)

    Bengtsson, J; Tjalsma, H; Rivolta, C; Hederstedt, L

    1999-01-01

    The sequence of the N-terminal end of the deduced ctaC gene product of Bacillus species has the features of a bacterial lipoprotein. CtaC is the subunit II of cytochrome caa(3), which is a cytochrome c oxidase. Using Bacillus subtilis mutants blocked in lipoprotein synthesis, we show that CtaC is a

  19. Characterization and biosynthesis of cytochrome b5 in rat liver microsomes

    Science.gov (United States)

    Sargent, J. R.; Vadlamudi, B. P.

    1968-01-01

    1. Cytochrome b5 is released from rat liver microsomes by both proteolytic enzymes and by treatments that disrupt phospholipids. Cytochrome P-420 is only released to a marked extent by treatments that disrupt phospholipids. 2. Cytochrome b5 was isolated in a pure state from both the rough and smooth fractions of rat liver microsomes after treatment with trypsin, and was shown to contain two cytochrome components with identical spectral properties. 3. Amino acid analyses of the two components are presented, together with peptide `fingerprint' patterns of tryptic digests of the two components. 4. Studies based on the direct isolation of cytochrome b5 after administration of a single dose of radioactive amino acid to rats demonstrate that the cytochrome is synthesized initially in the rough fraction of microsomes and only subsequently appears in the smooth fraction. 5. Isolated rat liver microsomes are capable of incorporating radioactive amino acids into cytochrome b5 under standard conditions. 6. Under these conditions the amino acid is incorporated into peptide linkage in the cytochrome. PMID:16742610

  20. Bioconversion of Mono- and Sesquiterpenoids by Recombinant Human Cytochrome P450 Monooxygenases

    NARCIS (Netherlands)

    Julsing, Mattijs K.; Fichera, Mario A.; Malz, Frank; Ebbelaar, Monique; Bos, Rein; Woerdenbag, Herman J.; Quax, Wim J.; Kayser, Oliver

    2008-01-01

    Cytochrome P450 monooxygenases play an important role in the biosynthesis and metabolism of terpenoids. We explored the potential of recombinant human liver cytochrome P450 monooxygenases CYP1A2, CYP2C9, and CYP3A4, heterologously expressed in Escherichia coli, to convert mono- and sesquiterpenoids

  1. Mitofilin regulates cytochrome c release during apoptosis by controlling mitochondrial cristae remodeling

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui-feng; Zhao, Guo-wei; Liang, Shu-ting; Zhang, Yuan; Sun, Li-hong [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Chen, Hou-zao, E-mail: houzao@gmail.com [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China); Liu, De-pei, E-mail: liudp@pumc.edu.cn [National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), 5 Dong Dan San Tiao, Beijing 100005 (China)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Mitofilin deficiency caused disruption of the cristae structures in HeLa cells. Black-Right-Pointing-Pointer Mitofilin deficiency reduced cell proliferation and increased cell sensitivity to apoptotic stimuli. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated the release of cytochrome c from mitochondria. Black-Right-Pointing-Pointer Mitofilin deficiency accelerated STS-induced intrinsic apoptotic pathway without interfering with the activation of Bax. -- Abstract: Mitochondria amplify caspase-dependent apoptosis by releasing proapoptotic proteins, especially cytochrome c. This process is accompanied by mitochondrial cristae remodeling. Our studies demonstrated that mitofilin, a mitochondrial inner membrane protein, acted as a cristae controller to regulate cytochrome c release during apoptosis. Knockdown of mitofilin in HeLa cells with RNAi led to fragmentation of the mitochondrial network and disorganization of the cristae. Mitofilin-deficient cells showed cytochrome c redistribution between mitochondrial cristae and the intermembrane space (IMS) upon intrinsic apoptotic stimuli. In vitro cytochrome c release experiments further confirmed that, compared with the control group, tBid treatment led to an increase in cytochrome c release from mitofilin-deficient mitochondria. Furthermore, the cells with mitofilin knockdown were more prone to apoptosis by accelerating cytochrome c release upon the intrinsic apoptotic stimuli than controls. Moreover, mitofilin deficiency did not interfere with the activation of proapoptotic member Bax upon intrinsic apoptotic stimuli. Thus, mitofilin distinctly functions in cristae remodeling and controls cytochrome c release during apoptosis.

  2. Antimycin-insensitive mutants of Candida utilis II. The effects of antimycin on Cytochrome b

    DEFF Research Database (Denmark)

    Grimmelikhuijzen, C J; Marres, C A; Slater, Conor

    1975-01-01

    1. Cytochrome b-562 is more reduced in submitochondrial particles of mutant 28 during the aerobic steady-state respiration with succinate than in particles of the wild type. When anaerobiosis is reached, the reduction of cytochrome b is preceded by a rapid reoxidation in the mutnat. A similar reo...

  3. Cytochrome P450-mediated metabolism of the synthetic cannabinoids UR-144 and XLR-11

    DEFF Research Database (Denmark)

    Nielsen, Line Marie; Holm, Niels Bjerre; Olsen, Lars

    2016-01-01

    In recent years, synthetic cannabinoids have emerged in the illicit drug market, in particular via the Internet, leading to abuse of these drugs. There is currently limited knowledge about the specific enzymes involved in the metabolism of these drugs. In this study, we investigated the cytochrome...... the specific CYP enzymes involved in the metabolism of UR-144 and XLR-11 utilizing a panel of nine recombinant enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 3A4, and 2E1). This is followed by an investigation of the effect of specific inhibitors targeted against CYP1A2, 2B6, 2C9, 2C19, 2D6 and 3A4 in human...... of UR-144 and XLR-11, while inhibition of the other CYP enzymes in HLM had only minor effects. Thus, CYP3A4 is the major contributor to the CYP mediated metabolism of UR-144 and XLR-11 with minor contributions from CYP1A2. Users of UR-144 and XLR-11 are thus subject to the influence of potential drug-drug...

  4. Respiratory system of Gluconacetobacter diazotrophicus PAL5. Evidence for a cyanide-sensitive cytochrome bb and cyanide-resistant cytochrome ba quinol oxidases.

    Science.gov (United States)

    González, B; Martínez, S; Chávez, J L; Lee, S; Castro, N A; Domínguez, M A; Gómez, S; Contreras, M L; Kennedy, C; Escamilla, J E

    2006-12-01

    In highly aerobic environments, Gluconacetobacter diazotrophicus uses a respiratory protection mechanism to preserve nitrogenase activity from deleterious oxygen. Here, the respiratory system was examined in order to ascertain the nature of the respiratory components, mainly of the cyanide sensitive and resistant pathways. The membranes of G. diazotrophicus contain Q(10), Q(9) and PQQ in a 13:1:6.6 molar ratios. UV(360 nm) photoinactivation indicated that ubiquinone is the electron acceptor for the dehydrogenases of the outer and inner faces of the membrane. Strong inhibition by rotenone and capsaicin and resistance to flavone indicated that NADH-quinone oxidoreductase is a NDH-1 type enzyme. KCN-titration revealed the presence of at least two terminal oxidases that were highly sensitive and resistant to the inhibitor. Tetrachorohydroquinol was preferentially oxidized by the KCN-sensitive oxidase. Neither the quinoprotein alcohol dehydrogenase nor its associated cytochromes c were instrumental components of the cyanide resistant pathway. CO-difference spectrum and photodissociation of heme-CO compounds suggested the presence of cytochromes b-CO and a(1)-CO adducts. Air-oxidation of cytochrome b (432 nm) was arrested by concentrations of KCN lower than 25 microM while cytochrome a(1) (442 nm) was not affected. A KCN-sensitive (I(50)=5 microM) cytochrome bb and a KCN-resistant (I(50)=450 microM) cytochrome ba quinol oxidases were separated by ion exchange chromatography.

  5. Retinal ganglion cells of high cytochrome oxidase activity in the rat

    Institute of Scientific and Technical Information of China (English)

    JENLS; CHAURMW

    1990-01-01

    Retinal ganglion cells in the rat were studied using the heavy metal intensified cytochrome oxidase and horseradish peroxidase histochemical methods.The results show that a population of large retinal ganglion cells was consistently observed with the cytochrome oxidase staining method in retinas of normal rats or rats which received unilateral thalamotomy at birth.These cytochrome oxidase rich ganglion cells appeared to have large somata,3-6 primary dendrites and extensive dendritic arbors,and are comparable to ganglion cells labeled by the wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP).However,the morphological details of some of the cells revealed by the cytochrome oxidase staining method are frequently better than those shown by the HRP histochemical method.These results suggest that the mitochondrial enzyme cytochrome oxidase can be used as a simple but reliable marker for identifying and studying a population of retinal genglion cells with high metabolic rate in the rat.

  6. Cytochrome oxidase as an indicator of ice storage and frozen storage

    DEFF Research Database (Denmark)

    Godiksen, Helene; Jessen, Flemming

    2001-01-01

    The potential of cytochrome oxidase as an indicator of ice storage and frozen storage of fish was investigated. Optimal assay conditions for cytochrome oxidase in a crude homogenate from cod muscle were studied. Maximal cytochrome oxidase activity was found at pH 6.5-7.5 and an assay temperature...... in different cods was 21%, and the coefficient of variation of different analyses on the same homogenate was 5%. It was shown that ice storage of muscle samples before they were frozen and thawed resulted in a major freezing-induced activation of cytochrome oxidase activity. The enzyme may therefore be used...... as an indicator of frozen fish to determine if the fish has been stored on ice before freezing. Cytochrome oxidase activity showed also potential as an indicator of frozen storage, as it was possible to distinguish between the frozen storage temperatures -9, -20, and -40 degreesC....

  7. Crystallization and micro FT-IR spectroscopy investigation of cytochrome bc1 complex

    Institute of Scientific and Technical Information of China (English)

    岳文海; 何季平; 谢荣; 徐建兴; 朱克莉; 翁诗甫

    1996-01-01

    A simple method to obtain large red crystals of cytochrome bc1 complex from beef heart mitochondria has been developed. These crystals are very stable. Their shapes are retained for a long time in tip-sealed Pasteur pipets placed in a refrigerator. The structure of crystalline cytochrome bc1 complex by micro FT-IR spectroscopy has been investigated. Based on the IR spectra of cytochrome c, the empirical assignments of the major infrared frequencies of cytochrome bc1 complex are given. Infrared frequencies and relative intensities of variable orientation and section of crystal are significantly different. These imply that infrared spectral characterization of the membrane protein crystallization is associated with the variable symmetries and orientations of the structure. Experimental results show that phospholipid exists in the crystal of cytochrome bc1 complex. The membrane protein is probably spanned on the mitochondrial membrane and buried in phospholipid bilayer in an asymmetric manner.

  8. Sequence Comparison of Partial Cytochrome b Genes of Two Coilia species

    Institute of Scientific and Technical Information of China (English)

    LIU Jinxian; GAO Tianxiang; WANG Yujiang; ZHANG Yaping

    2005-01-01

    Sequence variation of partial cytochrome b genes between two Coilia species, C. ectenes and C. mystus, was investigated. Of the 402 nucleotides, twenty-seven (6.72%) are polymorphic and all are synonymous substitutions. At the third positions of genetic condon of cytochrome b gene, the two species show an extreme anti-G bias (< 4 % ) and a pronounced bias towards A and C (>68%). There is no amino acid sequence divergence between the partial cytochrome b genes of the two species, indicating a close genetic relationship between them. The k-2p genetic distance of partial cytochrome b segment of the two species is 0.072, suggesting that the species were separated 3.6 Ma ago, in the middle Pliocene. Our result reveals that the cytochrome b gene is an appropriate marker for studies of population genetic structures and phylogeographic patterns of the two species.

  9. Cytochromes c': Structure, Reactivity and Relevance to Haem-Based Gas Sensing.

    Science.gov (United States)

    Hough, Michael A; Andrew, Colin R

    2015-01-01

    Cytochromes c' are a group of class IIa cytochromes with pentacoordinate haem centres and are found in photosynthetic, denitrifying and methanotrophic bacteria. Their function remains unclear, although roles in nitric oxide (NO) trafficking during denitrification or in cellular defence against nitrosoative stress have been proposed. Cytochromes c' are typically dimeric with each c-type haem-containing monomer folding as a four-α-helix bundle. Their hydrophobic and crowded distal sites impose severe restrictions on the binding of distal ligands, including diatomic gases. By contrast, NO binds to the proximal haem face in a similar manner to that of the eukaryotic NO sensor, soluble guanylate cyclase and bacterial analogues. In this review, we focus on how structural features of cytochromes c' influence haem spectroscopy and reactivity with NO, CO and O2. We also discuss the relevance of cytochrome c' to understanding the mechanisms of gas binding to haem-based sensor proteins.

  10. [Variability of nucleotide sequences of the mitochondrial DNA cytochrome c gene in dolly varden and taranetz char].

    Science.gov (United States)

    Radchenko, O A; Derenko, M V; Maliarchuk, B A

    2000-07-01

    Nucleotide sequence of the 307-bp fragment of the mitochondrial DNA cytochrome b gene was determined in representatives of the three species of the Salvelinus genus, specifically, dolly varden char (S. malma), taranetz char (S. taranetzi), and white-spotted char (S. leucomaenis). These results pointed to a high level of mitochondrial DNA (mtDNA) divergence between white-spotted char and dolly varden char, on the one hand, and taranetz char, on the other (the mean d value was 5.45%). However, the divergence between the dolly varden char and taranetz char was only 0.81%, which is comparable with the level of intraspecific divergence in the dolly varden char (d = 0.87%). It was shown that the dolly varden char mitochondrial gene pool contained DNA lineages differing from the main mtDNA pool at least in the taranetz char-specific mitochondrial lineages. One of these dolly varden char mtDNA lineages was characterized by the presence of the restriction endonuclease MspI-D variant of the cytochrome b gene. This lineage was widely distributed in the Chukotka populations but it was not detected in the Yana River (Okhotsk sea) populations. These findings suggest that dolly varden char has a more ancient evolutionary lineage, diverging from the common ancestor earlier than did taranetz char.

  11. Specific Phobias

    Science.gov (United States)

    ... Mental Health This information in Spanish ( en español ) Specific phobias Treatment More information on specific phobias A specific ... targeted psychotherapy. Return to top More information on Specific phobias Explore other publications and websites Phobias (Copyright © American ...

  12. On the role of cytochrome c8 in photosynthetic electron transfer of the purple non-sulfur bacterium Rhodoferax fermentans

    DEFF Research Database (Denmark)

    Hochkoeppler, Alejandro; Ciurli, Stefano; Kofod, Pauli

    1997-01-01

    of +285 mV. Partial analysis of the N-terminus amino-acid sequence shows a high similarity with cytochromes of c8 type (formerly called Pseudomonas cytochrome c-551 type). Time-resolved spectrophotometric studies show that this cytochrome c8 reduces the tetraheme subunit of the photosynthetic reaction...

  13. Rotating Massive Main-Sequence Stars II: Simulating a Population of LMC early B-type Stars as a Test of Rotational Mixing

    CERN Document Server

    Brott, Ines; Hunter, Ian; de Koter, Alex; Langer, Norbert; Dufton, Philip L; Cantiello, Matteo; Trundle, Carrie; Lennon, Danny J; de Mink, Selma E; Yoon, Sung-Chul; Anders, Peter

    2011-01-01

    Rotational mixing in massive stars is a widely applied concept, with far reaching consequences for stellar evolution. Nitrogen surface abundances for a large and homogeneous sample of massive B-type stars in the LMC were obtained by the VLT-FLAMES Survey of Massive Stars. This sample is the first covering a broad range of projected stellar rotational velocities, with a large enough sample of high quality data to allow for a statistically significant analysis. We use the sample to provide the first rigorous test of the theory of rotational mixing in massive stars. We calculated a grid of stellar evolution models, using the FLAMES sample to calibrate some of the uncertain mixing processes. We developed a new population-synthesis code, which uses this grid to simulate a large population of stars with masses, ages and rotational velocity distributions consistent with those from the FLAMES sample. The synthesized population is then filtered by the selection effects in the observed sample, to enable a direct compar...

  14. B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa

    CERN Document Server

    Fossati, L; Morel, T; Langer, N; Briquet, M; Carroll, T A; Hubrig, S; Nieva, M F; Oskinova, L M; Przybilla, N; Schneider, F R N; Scholler, M; Simon-Diaz, S; Ilyin, I; de Koter, A; Reisenegger, A; Sana, H

    2014-01-01

    Within the context of the "B fields in OB stars (BOB)" collaboration, we used the HARPSpol spectropolarimeter to observe the early B-type stars beta CMa (HD44743; B1 II/III) and epsilon CMa (HD52089; B1.5 II). For both stars, we consistently detected the signature of a weak (<30 G in absolute value) longitudinal magnetic field. We determined the physical parameters of both stars and characterise their X-ray spectrum. For beta CMa, our mode identification analysis led to determining a rotation period of 13.6+/-1.2 days and of an inclination angle of the rotation axis of 57.6+/-1.7 degrees, with respect to the line of sight. On the basis of these measurements and assuming a dipolar field geometry, we derived a best fitting obliquity of ~22 degrees and a dipolar magnetic field strength (Bd) of ~100 G (60

  15. Prevalence of the B Type Raf Kinase V600E Mutation in Cytologically Indeterminate Thyroid Nodules: Correlation with Ultrasonographic and Pathologic Features

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chae Hyun; Choi, Yoon Jung; Choi, Seon Hyeong; Rho, Myong Ho Kook Shin Ho; Chung, Eun Chul [Dept. of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University College of Medicine, Seoul (Korea, Republic of); Chae, Seoung Wan; Kim, Dong Hoon; Sohn, Jin Hee [Dept. of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University College of Medicine, Seoul (Korea, Republic of); Yun, Ji Sup [Dept. of Radiology, Kangbuk Samsung Hospital, Sungkyunkwan University College of Medicine, Seoul (Korea, Republic of)

    2012-01-15

    To study the prevalence of B type Raf kinase (BRAF) mutations, and to evaluate the ultrasonographic and clinicopathological features associated with thyroid cytology of indeterminate nodules. We assessed the presence or absence of BRAF mutation in 44 specimens from patients with cytologically indeterminate thyroid nodules according to two consecutive preoperative fine needle aspiration cytology procedures. In 9 specimens, the test for BRAF mutation was not possible due to scant cellularity. DNA was extracted from the atypical cells and then analyzed for the BRAF V600E mutation by pyrosequencing. The ultrasonographic and clinicopathological features of the patients were characterized according to their mutation status. The BRAF V600E mutation was present in 17 (48.6%) of 35 patients with indeterminate cytology results and in 17 (54.8%) of the 31 patients with papillary thyroid cancer (PTC). Twenty two of 35 cytologically indeterminate nodules had calcifications, and among them 14 cases were proven to be positive for BRAF V600E mutations. Extrathyroid extension was significantly more frequent in the presence of the BRAF V600E mutation (p = 0.027), while tumor size, lympho-vascular invasion, or lymph node metastasis were not associated with the mutation. Screening for BRAF V600E mutations in conjunction with cytology may increase the diagnostic accuracy for PTC with indeterminate cytology results.

  16. N-terminal pro b-type natriuretic peptide (NT-pro-BNP) -based score can predict in-hospital mortality in patients with heart failure.

    Science.gov (United States)

    Huang, Ya-Ting; Tseng, Yuan-Teng; Chu, Tung-Wei; Chen, John; Lai, Min-Yu; Tang, Woung-Ru; Shiao, Chih-Chung

    2016-07-14

    Serum N-terminal pro b-type natriuretic peptide (NT-pro-BNP) testing is recommended in the patients with heart failure (HF). We hypothesized that NT-pro-BNP, in combination with other clinical factors in terms of a novel NT-pro BNP-based score, may provide even better predictive power for in-hospital mortality among patients with HF. A retrospective study enrolled adult patients with hospitalization-requiring HF who fulfilled the predefined criteria during the period from January 2011 to December 2013. We proposed a novel scoring system consisting of several independent predictors including NT-pro-BNP for predicting in-hospital mortality, and then compared the prognosis-predictive power of the novel NT-pro BNP-based score with other prognosis-predictive scores. A total of 269 patients were enrolled in the current study. Factors such as "serum NT-pro-BNP level above 8100 mg/dl," "age above 79 years," "without taking angiotensin converting enzyme inhibitors/angiotensin receptor blocker," "without taking beta-blocker," "without taking loop diuretics," "with mechanical ventilator support," "with non-invasive ventilator support," "with vasopressors use," and "experience of cardio-pulmonary resuscitation" were found as independent predictors. A novel NT-pro BNP-based score composed of these risk factors was proposed with excellent predictability for in-hospital mortality. The proposed novel NT-pro BNP-based score was extremely effective in predicting in-hospital mortality in HF patients.

  17. Cardiac tamponade as an independent condition affecting the relationship between the plasma B-type natriuretic peptide levels and cardiac function.

    Science.gov (United States)

    Minai, Kosuke; Komukai, Kimiaki; Arase, Satoshi; Nagoshi, Tomohisa; Matsuo, Seiichiro; Ogawa, Kazuo; Kayama, Yosuke; Inada, Keiichi; Tanigawa, Shin-Ichi; Takemoto, Tomoyuki; Sekiyama, Hiroshi; Date, Taro; Ogawa, Takayuki; Taniguchi, Ikuo; Yoshimura, Michihiro

    2013-07-01

    Plasma B-type natriuretic peptide (BNP) is finely regulated by the cardiac function and several extracardiac factors. Therefore, the relationship between the plasma BNP levels and the severity of heart failure sometimes seems inconsistent. The purpose of the present study was to investigate the plasma BNP levels in patients with cardiac tamponade and their changes after pericardial drainage. This study included 14 patients with cardiac tamponade who underwent pericardiocentesis. The cardiac tamponade was due to malignant diseases in 13 patients and uremia in 1 patient. The plasma BNP levels were measured before and 24-48 h after drainage. Although the patients reported severe symptoms of heart failure, their plasma BNP levels were only 71.2 ± 11.1 pg/ml before drainage. After appropriate drainage, the plasma BNP levels increased to 186.0 ± 22.5 pg/ml, which was significantly higher than that before drainage (P = 0.0002). In patients with cardiac tamponade, the plasma BNP levels were low, probably because of impaired ventricular stretching, and the levels significantly increased in response to the primary condition after drainage. This study demonstrates an additional condition that affects the relationship between the plasma BNP levels and cardiac function. If inconsistency is seen in the relationship between the plasma BNP levels and clinical signs of heart failure, the presence of cardiac tamponade should therefore be considered.

  18. Chemical surface inhomogeneities in late B-type stars with Hg and Mn peculiarity I Spot evolution in HD 11753 on short and long time scales

    CERN Document Server

    Korhonen, H; Briquet, M; Soriano, M Flores; Hubrig, S; Savanov, I; Hackman, T; Ilyin, I V; Eulaers, E; Pessemier, W

    2013-01-01

    Aims: Time series of high-resolution spectra of the late B-type star HD 11753 exhibiting HgMn chemical peculiarity are used to study the surface distribution of different chemical elements and their temporal evolution. Methods: High-resolution and high signal-to-noise ratio spectra were obtained using the CORALIE spectrograph at La Silla in 2000, 2009, and 2010. Surface maps of YII, SrII, TiII, and CrII were calculated using the Doppler imaging technique. The results were also compared to equivalent width measurements. The evolution of chemical spots both on short and long time scales were investigated. Results: We determine the binary orbit of HD 11753 and fine-tune the rotation period of the primary. The earlier discovered fast evolution of the chemical spots is confirmed by an analysis using both the chemical spot maps and equivalent width measurements. In addition, a long-term decrease in the overall YII and SrII abundances is discovered. A detailed analysis of the chemical spot configurations reveals som...

  19. Attenuation of monocyte chemotaxis--a novel anti-inflammatory mechanism of action for the cardio-protective hormone B-type natriuretic peptide.

    Science.gov (United States)

    Glezeva, Nadezhda; Collier, Patrick; Voon, Victor; Ledwidge, Mark; McDonald, Kenneth; Watson, Chris; Baugh, John

    2013-08-01

    B-type natriuretic peptide (BNP) is a prognostic and diagnostic marker for heart failure (HF). An anti-inflammatory, cardio-protective role for BNP was proposed. In cardiovascular diseases including pressure overload-induced HF, perivascular inflammation and cardiac fibrosis are, in part, mediated by monocyte chemoattractant protein (MCP)1-driven monocyte migration. We aimed to determine the role of BNP in monocyte motility to MCP1. A functional BNP receptor, natriuretic peptide receptor-A (NPRA) was identified in human monocytes. BNP treatment inhibited MCP1-induced THP1 (monocytic leukemia cells) and primary monocyte chemotaxis (70 and 50 %, respectively). BNP did not interfere with MCP1 receptor expression or with calcium. BNP inhibited activation of the cytoskeletal protein RhoA in MCP1-stimulated THP1 (70 %). Finally, BNP failed to inhibit MCP1-directed motility of monocytes from patients with hypertension (n = 10) and HF (n = 6) suggesting attenuation of this anti-inflammatory mechanism in chronic heart disease. We provide novel evidence for a direct role of BNP/NPRA in opposing human monocyte migration and support a role for BNP as a cardio-protective hormone up-regulated as part of an adaptive compensatory response to combat excess inflammation.

  20. Comparative Analysis of A, B Type and Exchange Traded Funds Performances with Mutual Fund Performance Measures, Regression Analysis and Manova Technique.

    Directory of Open Access Journals (Sweden)

    Mehmet Arslan

    2010-06-01

    Full Text Available The objective of the study is to evaluate risk- reward relationship and relative performances of the 4 different groups of mutual funds. To this end, daily return data of these 12 mutual funds (3 type variable fund; 3 B type variable fund; 3 A type stock fund and 3 A type Exchange traded fund together with daily market index (imkb100 return and daily return of riskless rate for the period from January 2006 to Feb 2010. The 180-day maturity T-Bill has been selected to represent riskless rate. To determine performances of mutual funds; Sharpe ratio, M2 measure, Treynor index, Jensen index, Sortino ratio, T2 ratio, Valuation ratio has been applied and these indicators produced conflicting results in ranking mutual funds. Then timingand selection capability of the fund manager has been determined by applying simple regression and Quadratic regression. Interestingly all funds found to have positive coefficient, indicating positive election capability of managers; but in terms of timing capability only one fund managers showed success. Finally, to determine extent to which mean returns are differs between mutual funds, market index (imkb100 and riskless rate (180 day TBill results of the analysis revealed that mean returns of individual security returns differs at P≤0,01 level. That shows instability in returns and poor ex-ante forecast modeling capability.

  1. Putative P1B-type ATPase from the bacterium Achromobacter xylosoxidans A8 alters Pb2+/Zn2+/Cd2+-resistance and accumulation in Saccharomyces cerevisiae.

    Science.gov (United States)

    Suman, Jachym; Kotrba, Pavel; Macek, Tomas

    2014-05-01

    PbtA, a putative P(1B)-type ATPase from the Gram-negative soil bacterium Achromobacter xylosoxidans A8 responsible for Pb(2+)/Zn(2+)/Cd(2+)-resistance in Escherichia coli, was heterologously expressed in Saccharomyces cerevisiae. When present in Zn(2+)- and Pb(2+)/Cd(2+)-hypersensitive S. cerevisiae strains CM137 and DTY168, respectively, PbtA was able to restore Zn(2+)- and Pb(2+)-resistant phenotype. At the same time, the increase of Pb, Zn, and Cd accumulation in yeast was observed. However, Cd(2+)-tolerance of the pbtA-bearing yeasts dramatically decreased. The PbtA-eGFP fusion protein was localized primarily in the tonoplast and also in the plasma membrane and the perinuclear region corresponding to the endoplasmic reticulum at later growth stages. This indicates that PbtA protein is successfully incorporated into membranes in yeasts. Since PbtA caused a substantial increase of Pb(2+)/Zn(2+)-resistance and accumulation in baker's yeast, we propose its further use for the genetic modification of suitable plant species in order to obtain an effective tool for the phytoremediation of sites polluted by toxic transition metals.

  2. PCR performance of the B-type DNA polymerase from the thermophilic euryarchaeon Thermococcus aggregans improved by mutations in the Y-GG/A motif

    Science.gov (United States)

    Böhlke, Kristina; Pisani, Francesca M.; Vorgias, Constantinos E.; Frey, Bruno; Sobek, Harald; Rossi, Mosè; Antranikian, Garabed

    2000-01-01

    The effect of mutations in the highly conserved Y-GG/A motif of B-type DNA polymerases was studied in the DNA polymerase from the hyperthermophilic euryarchaeon Thermococcus aggregans. This motif plays a critical role in the balance between the synthesis and degradation of the DNA chain. Five different mutations of the tyrosine at position 387 (Tyr387→Phe, Tyr387→Trp, Tyr387→His, Tyr387→Asn and Tyr387→Ser) revealed that an aromatic ring system is crucial for the synthetic activity of the enzyme. Amino acids at this position lacking the ring system (Ser and Asn) led to a significant decrease in polymerase activity and to enhanced exonuclease activity, which resulted in improved enzyme fidelity. Exchange of tyrosine to phenylalanine, tryptophan or histidine led to phenotypes with wild-type-like fidelity but enhanced PCR performance that could be related to a higher velocity of polymerisation. With the help of a modelled structure of T.aggregans DNA polymerase, the biochemical data were interpreted proposing that the conformation of the flexible loop containing the Y-GG/A motif is an important factor for the equilibrium between DNA polymerisation and exonucleolysis. PMID:11024170

  3. NLTE carbon abundance determination in selected A- and B-type stars and the interpretation of C\\ione\\ emission lines

    CERN Document Server

    Alexeeva, S A; Mashonkina, L I

    2016-01-01

    We constructed a comprehensive model atom for C\\ione\\ -- C\\ii\\ using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for C\\ione\\ and C\\ii\\ in classical 1D models representing the atmospheres of A and late B-type stars. Our NLTE calculations predict the emission that appears at effective temperature of 9250 to 10\\,500~K depending on log~$g$ in the C\\ione\\ 8335, 9405\\,\\AA\\ singlet lines and at \\Teff~$>$~15\\,000~K (log~$g$ = 4) in the C\\ione\\ 9061 -- 9111\\,\\AA\\,, 9603 -- 9658\\,\\AA\\, triplet lines. A prerequisite of the emission phenomenon is the overionization-recombination mechanism resulting in a depopulation of the lower levels of C\\ione\\ to a greater extent than the upper levels. Extra depopulation of the lower levels of the transitions corresponding to the near-infrared lines, is caused by photon loss in the UV lines C\\ione\\ 2479, 1930, and 1657\\,\\AA. We analysed the lines of C\\ione\\ and C\\ii\\ in Vega, HD~73666, Sirius, 21~Peg, $\\pi$~Cet,...

  4. Reference intervals for N-terminal pro-B-type natriuretic peptide in amniotic fluid between 10 and 34 weeks of gestation.

    Directory of Open Access Journals (Sweden)

    Waltraut M Merz

    Full Text Available BACKGROUND: In adult and pediatric cardiology, n-terminal pro-B-type natriuretic peptide (nt-proBNP serves as biomarker in the diagnosis and management of cardiovascular dysfunction. Elevated levels of circulating nt-proBNP are present in fetal conditions associated with myocardial pressure or volume load. Compared to fetal blood sampling, amniocentesis is technically easier and can be performed from early pregnancy onwards. We aimed to investigate amniotic fluid (AF nt-proBNP concentrations in normal pregnancies between 10 and 34 weeks of gestation. METHODS: Nt-proBNP and total protein (TP was measured in AF by chemiluminescence assay (photometry, respectively. To adjust for a potential dilutional effect, the AF-nt-proBNP/AF-TP ratio was analyzed. Reference intervals were constructed by regression modeling across gestational age. RESULTS: 132 samples were analyzed. A negative correlation between AF-nt-proBNP/AF-TP ratio and gestational age was observed. Curves for the mean and the 5% and 95% reference interval between 10 and 34 weeks of gestation were established. CONCLUSION: In normal pregnancy, nt-proBNP is present in AF and decreases during gestation. Our data provide the basis for research on AF-nt-proBNP as biomarker in fetal medicine.

  5. B-Type Natriuretic Peptide Deletion Leads to Progressive Hypertension, Associated Organ Damage, and Reduced Survival: Novel Model for Human Hypertension.

    Science.gov (United States)

    Holditch, Sara J; Schreiber, Claire A; Nini, Ryan; Tonne, Jason M; Peng, Kah-Whye; Geurts, Aron; Jacob, Howard J; Burnett, John C; Cataliotti, Alessandro; Ikeda, Yasuhiro

    2015-07-01

    Altered myocardial structure and function, secondary to chronically elevated blood pressure, are leading causes of heart failure and death. B-type natriuretic peptide (BNP), a guanylyl cyclase A agonist, is a cardiac hormone integral to cardiovascular regulation. Studies have demonstrated a causal relationship between reduced production or impaired BNP release and the development of human hypertension. However, the consequences of BNP insufficiency on blood pressure and hypertension-associated complications remain poorly understood. Therefore, the goal of this study was to create and characterize a novel model of BNP deficiency to investigate the effects of BNP absence on cardiac and renal structure, function, and survival. Genetic BNP deletion was generated in Dahl salt-sensitive rats. Compared with age-matched controls, BNP knockout rats demonstrated adult-onset hypertension. Increased left ventricular mass with hypertrophy and substantially augmented hypertrophy signaling pathway genes, developed in young adult knockout rats, which preceded hypertension. Prolonged hypertension led to increased cardiac stiffness, cardiac fibrosis, and thrombi formation. Significant elongation of the QT interval was detected at 9 months in knockout rats. Progressive nephropathy was also noted with proteinuria, fibrosis, and glomerular alterations in BNP knockout rats. End-organ damage contributed to a significant decline in overall survival. Systemic BNP overexpression reversed the phenotype of genetic BNP deletion. Our results demonstrate the critical role of BNP defect in the development of systemic hypertension and associated end-organ damage in adulthood.

  6. Studies on NADH (NADPH)-cytochrome c reductase (FMN-containing) from yeast. Isolation and physicochemical properties of the enzyme from top-fermenting ale yeast.

    Science.gov (United States)

    Johnson, M S; Kuby, S A

    1985-10-05

    Only three major NADPH-nitrotetrazolium blue (NTB) reductases may be detected in a unique top-ale yeast (Saccharomyces cerevisiae, Narragansett strain), which appears to be of a near anaerobic type with the absence of cytochromes c and a/a3 and the presence of cytochromes P-450 and b5. Two of these three major NADPH-NTB reductases possessed NADH-NTB reductase activity; the third was specific for NADPH and was isolated in this laboratory (Tryon, E., Cress, M. C., Hamada, M., and Kuby, S. A. (1979) Arch. Biochem. Biophys. 197, 104-118) vis. NADPH-cytochrome c reductase (FAD-containing). A description of the isolation procedure is provided for one of these two NADH(NADPH)-NTB reductases, viz. NADH(NADPH)-cytochrome c reductase (FMN-containing), which accounts for about one-half of the total cyanide-insensitive menadione-activated respiration of this yeast. This NADH(NADPH)-cytochrome c reductase has been isolated from an extract of an acetone powder of the top-fermenting ale yeast, with an apparent purification of more than 67-fold and a final specific activity of 0.41 and 0.31 mumol/min/mg for NADH- and NADPH-dependent reduction, respectively. The isolated enzyme proved to be homogeneous by electrophoresis on cellulose acetate and on polyacrylamide gels. It had a pI of 5.25 (at gamma/2 = 0.05) and a molecular size under nondenaturing conditions (as determined by chromatography on Sephadex G-100 and Sephacryl S-200) of 70,000 daltons. On denaturation, the enzyme dissociated into two similar, if not identical, subunits which possessed a molecular weight of 34,000 by sodium dodecyl sulfate/urea-polyacrylamide gel electrophoresis and a weight average molecular weight of 35,000 by sedimentation equilibrium in the presence of 4.0 M guanidinium chloride. The absorbance spectrum of NADH(NADPH)-cytochrome c reductase (FMN-containing) showed three maxima at 464, 383, and 278 nm, with extinction coefficients of 9.88, 9.98, and 64.6 mM-1 cm-1, respectively. The reductase, as

  7. Bromopropylate: induction of hepatic cytochromes P450 and absence of covalent binding to DNA in mouse liver.

    Science.gov (United States)

    Thomas, H; Sagelsdorff, P; Molitor, E; Skripsky, T; Waechter, F

    1994-11-01

    Oral administration of benzilic acid ester-based acaricide bromopropylate at daily doses of 3, 15, 100, and 300 mg/kg body wt to young adult male Tif:MAGf mice for 14 days caused slightly increased liver weights in the high-dose group. A dose-dependent increase of the microsomal cytochrome P450 content was accompanied by elevated ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, pentoxyresorufin O-depentylase, and total testosterone hydroxylase activities. When compared with mice treated in parallel with the model compounds for hepatic xenobiotic metabolizing enzyme induction, phenobarbitone, and 3-methylcholanthrene, the enzyme activity changes observed with bromopropylate largely equalled those expressed in phenobarbitone-treated mice. Immunochemical studies with monoclonal antibodies against rat liver cytochrome P450 isoenzymes of the gene families 1A, 2B, 3A, and 4A confirmed that bromopropylate is a phenobarbitone-type inducer in the mouse liver. Titration of liver microsomal suspensions with bromopropylate yielded Type I substrate binding spectra. The specific amplitude was increased 1.5-fold when microsomes from bromopropylate-treated mice (300 mg/kg body wt) were used instead of control microsomes, indicating the induction of cytochromes P450 catalyzing the oxidative metabolism of the test compound. Single oral administration of 300 mg/kg body wt [14C]bromopropylate to male mice, without or following pretreatment for 14 days with 300 mg/kg body wt unlabeled bromopropylate, gave no indication for DNA binding of the test compound in the liver. This excludes a genotoxic potential via covalent DNA modification. The results suggest that, in analogy to phenobarbitone, bromopropylate acts as a tumor promotor rather than a tumor initiator in the mouse liver.

  8. Cyanide - Mechanism of Prophylaxis and Effect on Cytochrome Oxidase.

    Science.gov (United States)

    1981-08-15

    152:1074-1077, 1958. Cooperstein, S. J. and Lazaro , A.: A microspectrophotometric method for the determination of cytochrome oxidase. J. biol. Chem...5 mg/kg); A--A CPZ + NaNO (100 mg/kg) + KCN (10 mg/kg); 0 -- 0 CPZ + Na2S203 (1 gm/kg) + KCN (15 mg/kg); A---A CPZ + NaNO2 (100 mg/)Cg) + Na2S203...chlorpromazine (10 mg/kg), NaqO 2 (100 w.g/kg) and A Na S 03 (1gm/kg). G - C Saline control; A - A KCN; S - CPZ + Na 2S 20 3+ KCN; 0 - 0 CPZ + NaNO 2 + KCN

  9. Personalized Cancer Therapy Considering Cytochrome P450 Variability.

    Science.gov (United States)

    Preissner, Saskia; Simmaco, Maurizio; Gentile, Giovanna; Preissner, Robert

    2015-01-01

    The individual variability of pharmacokinetics is underestimated and few systematic studies exist in this field. In most cases, this leads to unwanted side effects or toxicity. In polychemotherapy, prodrugs (like ifosfamide), which have to be activated by cytochrome P450 enzymes (CYPs), play an important role. If patients are poor metabolizers for these drugs, the therapy will be ineffective. Furthermore, CYPs and transporters can be (over)expressed in target tissues, which is also not examined and considered in clinical routine. Here, we present a body map showing relevant enzymes in some organs and tissues. Finally, a typical case of a Caucasian chemotherapy patient with breast cancer is presented and discussed regarding a personalized cancer therapy considering the single nucleotide polymorphisms found via genotyping.

  10. Highly selective ligand binding by Methylophilus methylotrophus cytochrome c''.

    Science.gov (United States)

    Quintas, Pedro O; Catarino, Teresa; Todorovic, Smilja; Turner, David L

    2011-06-28

    Cytochrome c'' (cyt c'') from Methylophilus methylotrophus is unusual insofar as the heme has two axial histidine ligands in the oxidized form but one is detached when the protein is reduced. Despite cyt c'' having an axial site available for binding small ligands, we show here that only NO binds readily to the ferrous cyt c''. Binding of CO, as well as CN(-), on the other hand requires considerable structural reorganization, or reduction of the disulfide bridge close to the heme. Standard free energies for the binding of NO and CO reveal high selectivity of the ferrous cyt c'' for NO, indicating its putative physiological role. In this work, we characterize in detail the kinetics of NO binding and the structural features of the Fe(2+)-NO adduct by stopped-flow and resonance Raman spectroscopy, respectively.

  11. [Cytochrome P450 enzymes and microbial drug development - A review].

    Science.gov (United States)

    Li, Zhong; Zhang, Wei; Li, Shengying

    2016-03-01

    Cytochrome P450 enzymes broadly exist in animals, plants and microorganisms. This superfamily of monooxygenases holds the greatest diversity of substrate structures and catalytic reaction types among all enzymes. P450 enzymes play important roles in natural product biosynthesis. In particular, P450 enzymes are capable of catalyzing the regio- and stereospecific oxidation of non-activated C-H bonds in complex organic compounds under mild conditions, which overrides many chemical catalysts. This advantage thus warrants their great potential in microbial drug development. In this review, we introduce a variety of P450 enzymes involved in natural product biosynthesis; provide a brief overview on protein engineering, biotransformation and practical application of P450 enzymes; and discuss the limits, challenges and prospects of industrial application of P450 enzymes.

  12. Cytochrome c peroxidase activity of heme bound amyloid β peptides.

    Science.gov (United States)

    Seal, Manas; Ghosh, Chandradeep; Basu, Olivia; Dey, Somdatta Ghosh

    2016-09-01

    Heme bound amyloid β (Aβ) peptides, which have been associated with Alzheimer's disease (AD), can catalytically oxidize ferrocytochrome c (Cyt c(II)) in the presence of hydrogen peroxide (H2O2). The rate of catalytic oxidation of Cyt(II) c has been found to be dependent on several factors, such as concentration of heme(III)-Aβ, Cyt(II) c, H2O2, pH, ionic strength of the solution, and peptide chain length of Aβ. The above features resemble the naturally occurring enzyme cytochrome c peroxidase (CCP) which is known to catalytically oxidize Cyt(II) c in the presence of H2O2. In the absence of heme(III)-Aβ, the oxidation of Cyt(II) c is not catalytic. Thus, heme-Aβ complex behaves as CCP.

  13. Structural Models for Cytochrome P450�Mediated Catalysis

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    David F.V. Lewis

    2003-01-01

    Full Text Available This review focuses on the structural models for cytochrome P450 that are improving our knowledge and understanding of the P450 catalytic cycle, and the way in which substrates bind to the enzyme leading to catalytic conversion and subsequent formation of mono-oxygenated metabolites. Various stages in the P450 reaction cycle have now been investigated using X-ray crystallography and electronic structure calculations, whereas homology modelling of mammalian P450s is currently revealing important aspects of pharmaceutical and other xenobiotic metabolism mediated by P450 involvement. These features are explored in the current review on P450-based catalysis, which emphasises the importance of structural modelling to our understanding of this enzyme's function. In addition, the results of various QSAR analyses on series of chemicals, which are metabolised via P450 enzymes, are presented such that the importance of electronic and other structural factors in explaining variations in rates of metabolism can be appreciated.

  14. Cytochrome b nucleotide sequence variation among the Atlantic Alcidae.

    Science.gov (United States)

    Friesen, V L; Montevecchi, W A; Davidson, W S

    1993-01-01

    Analysis of cytochrome b nucleotide sequences of the six extant species of Atlantic alcids and a gull revealed an excess of adenines and cytosines and a deficit of guanines at silent sites on the coding strand. Phylogenetic analyses grouped the sequences of the common (Uria aalge) and Brünnich's (U. lomvia) guillemots, followed by the razorbill (Alca torda) and little auk (Alle alle). The black guillemot (Cepphus grylle) sequence formed a sister taxon, and the puffin (Fratercula arctica) fell outside the other alcids. Phylogenetic comparisons of substitutions indicated that mutabilities of bases did not differ, but that C was much more likely to be incorporated than was G. Imbalances in base composition appear to result from a strand bias in replication errors, which may result from selection on secondary RNA structure and/or the energetics of codon-anticodon interactions.

  15. Active site dynamics of toluene hydroxylation by cytochrome P-450

    Energy Technology Data Exchange (ETDEWEB)

    Hanzlik, R.P.; Kahhiing John Ling (Univ. of Kansas, Lawrence (United States))

    1990-06-22

    Rat liver cytochrome P-450 hydroxylates toluene to benzyl alcohol plus o-, m-, and p-cresol. Deuterated toluenes were incubated under saturating conditions with liver microsomes from phenobarbital-pretreated rats, and product yields and ratios were measured. Stepwise deuteration of the methyl leads to stepwise decreases in the alcohol/cresol ratio without changing the cresol isomer ratios. Extensive deuterium retention in the benzyl alcohols from PhCH{sub 2}D and PhCHD{sub 2} suggests there is a large intrinsic isotope effect for benzylic hydroxylation. After replacement of the third benzylic H by D, the drop in the alcohol/cresol ratio was particularly acute, suggsting that metabolic switching from D to H within the methyl group was easier than switching from the methyl to the ring. Comparison of the alcohol/cresol ratio for PhCH{sub 3} vs PhCD{sub 3} indicated a net isotope effect of 6.9 for benzylic hydroxylation. From product yield data for PhCH{sub 3} and PhCD{sub 3}, {sup D}V for benzyl alcohol formation is only 1.92, whereas {sup D}V for total product formation is 0.67 (i.e., inverse). From competitive incubations of PhCH{sub 3}/PhCD{sub 3} mixtures {sup D}(V/K) isotope effects on benzyl alcohol formation and total product formation (3.6 and 1.23, respectively) are greatly reduced, implying strong commitment to catalysis. In contrast, {sup D}(V/K) for the alcohol/cresol ratio is 6.3, indicating that the majority of the intrinsic isotope effect is expressed through metabolic switching. Overall, these data are consistent with reversible formation of a complex between toluene and the active oxygen form of cytochrome P-450, which rearranges internally and reacts to form products faster than it dissociates back to release substrate.

  16. Prognostic relevance of cytochrome C oxidase in primary glioblastoma multiforme.

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    Corinne E Griguer

    Full Text Available Patients with primary glioblastoma multiforme (GBM have one of the lowest overall survival rates among cancer patients, and reliable biomarkers are necessary to predict patient outcome. Cytochrome c oxidase (CcO promotes the switch from glycolytic to OXPHOS metabolism, and increased CcO activity in tumors has been associated with tumor progression after chemotherapy failure. Thus, we investigated the relationship between tumor CcO activity and the survival of patients diagnosed with primary GBM. A total of 84 patients with grade IV glioma were evaluated in this retrospective cohort study. Cumulative survival was calculated by the Kaplan-Meier method and analyzed by the log-rank test, and univariate and multivariate analyses were performed with the Cox regression model. Mitochondrial CcO activity was determined by spectrophotometrically measuring the oxidation of cytochrome c. High CcO activity was detected in a subset of glioma tumors (∼30%, and was an independent prognostic factor for shorter progression-free survival and overall survival [P = 0.0087 by the log-rank test, hazard ratio = 3.57 for progression-free survival; P<0.001 by the log-rank test, hazard ratio = 10.75 for overall survival]. The median survival time for patients with low tumor CcO activity was 14.3 months, compared with 6.3 months for patients with high tumor CcO activity. High CcO activity occurs in a significant subset of high-grade glioma patients and is an independent predictor of poor outcome. Thus, CcO activity may serve as a useful molecular marker for the categorization and targeted therapy of GBMs.

  17. Mode of Antifungal Drugs Interaction with Cytochrome P- 450

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    M- Mahmodian

    1991-07-01

    Full Text Available Computer was used to identify the interactions of substrates and antifungal drugs with the enzyme, Cytochrome P-450; and then Molplot.bas computer program was applied to get three dimensional figures of 5-hydroxy camphor.oxidation products of camphor analogues, and antifungal drugs.Cartesian characteristics of atoms building molecules, are taken from Buildz. for program, which can calculate X,Y,Z coordinates of atoms by Zmatrix data. The other program which can calculate X,Y,Z coordinates, using fractional characteristics, is the Coord, for program that, gives our cartesian characteristics of the atoms of molecule, then by using these data, we obtain three dimensional figures and distance between active atoms in compounds under consideration. Results show that distance between two oxygen atoms in 5-exo-hydroxy- camphor and the other compounds obtained from oxidation of camphor analogues, with the distance of two oxygen atoms in antifungal compounds under discussion are equal. Therefore, we can conclude that, the antifungal molecule also interacts with enzyme's active site, by its own sites, in a similar manner to the 5-hydroxy camphor molecule, which is:"n1. Nitrogen atom (N of Imidazole and Triazole ring in antifungal molecule with Iron atom in heam molecule belonging to Cytochrome P-450 enzyme, are coordinated."n2. The other atoms such as : 0,S or N in structure of the antifungal drug are coordinated with hydrogen atom of hydroxyl group belong ing to Tyr-96 in the structure of enzyme, forming hydrogen bonding.

  18. Protonation State-Dependent Communication in Cytochrome c Oxidase.

    Science.gov (United States)

    Helabad, Mahdi Bagherpoor; Ghane, Tahereh; Reidelbach, Marco; Woelke, Anna Lena; Knapp, Ernst Walter; Imhof, Petra

    2016-08-09

    Proton transfer in cytochrome c oxidase from the cellular inside to the binuclear redox center (BNC) can occur through two distinct pathways, the D- and K-channels. For the protein to function as both redox enzyme and proton pump, proton transfer out of either of the channels toward the BNC or into the protein toward a proton loading site, and ultimately through the membrane, must be highly regulated. The O→E intermediate of cytochrome c oxidase is the first redox state in its catalytic cycle, where proton transfer through the K-channel, from K362 to Y288 at the BNC, is important. Molecular dynamics simulations of this intermediate with 16 different combinations of protonation states of key residues in the D- and K-channel show the mutual impact of the two proton-conducting channels to be protonation state-dependent. Strength as well as means of communication, correlations in positions, or connections along the hydrogen-bonded network, change with the protonation state of the K-channel residue K362. The conformational and hydrogen-bond dynamics of the D-channel residue N139 regulated by an interplay of protonation in the D-channel and K362. N139 thus assumes a gating function by which proton passage through the D-channel toward E286 is likely facilitated for states with protonated K362 and unprotonated E286, which would in principle allow proton transfer to the BNC, but no proton pumping until a proton has reached E286.

  19. Genomic Analyses of Bacterial Porin-Cytochrome Gene Clusters

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    Liang eShi

    2014-11-01

    Full Text Available The porin-cytochrome (Pcc protein complex is responsible for trans-outer membrane electron transfer during extracellular reduction of Fe(III by the dissimilatory metal-reducing bacterium Geobacter sulfurreducens PCA. The identified and characterized Pcc complex of G. sulfurreducens PCA consists of a porin-like outer-membrane protein, a periplasmic 8-heme c-type cytochrome (c-Cyt and an outer-membrane 12-heme c-Cyt, and the genes encoding the Pcc proteins are clustered in the same regions of genome (i.e., the pcc gene clusters of G. sulfurreducens PCA. A survey of additionally microbial genomes has identified the pcc gene clusters in all sequenced Geobacter spp. and other bacteria from six different phyla, including Anaeromyxobacter dehalogenans 2CP-1, A. dehalogenans 2CP-C, Anaeromyxobacter sp. K, Candidatus Kuenenia stuttgartiensis, Denitrovibrio acetiphilus DSM 12809, Desulfurispirillum indicum S5, Desulfurivibrio alkaliphilus AHT2, Desulfurobacterium thermolithotrophum DSM 11699, Desulfuromonas acetoxidans DSM 684, Ignavibacterium album JCM 16511, and Thermovibrio ammonificans HB-1. The numbers of genes in the pcc gene clusters vary, ranging from two to nine. Similar to the metal-reducing (Mtr gene clusters of other Fe(III-reducing bacteria, such as Shewanella spp., additional genes that encode putative c-Cyts with predicted cellular localizations at the cytoplasmic membrane, periplasm and outer membrane often associate with the pcc gene clusters. This suggests that the Pcc-associated c-Cyts may be part of the pathways for extracellular electron transfer reactions. The presence of pcc gene clusters in the microorganisms that do not reduce solid-phase Fe(III and Mn(IV oxides, such as D. alkaliphilus AHT2 and I. album JCM 16511, also suggests that some of the pcc gene clusters may be involved in extracellular electron transfer reactions with the substrates other than Fe(III and Mn(IV oxides.

  20. High morpholine degradation rates and formation of cytochrome P450 during growth on different cyclic amines by newly isolated Mycobacterium sp. strain HE5.

    Science.gov (United States)

    Schräder, T; Schuffenhauer, G; Sielaff, B; Andreesen, J R

    2000-05-01

    Using morpholine as sole source of carbon, nitrogen and energy, strain HE5 (DSM 44238) was isolated from forest soil. The isolated strain was identified as a member of the subgroup of fast-growing Mycobacterium species as revealed by 16S rDNA analysis. An identity of 99.4% was obtained to Mycobacterium gilvum; however, the type strain was unable to utilize morpholine. A maximal growth rate of 0.17 h(-1) was observed at a morpholine concentration of 30 mM, 30 degrees C and pH 7.2. The substrate was tolerated at concentrations up to 100 mM. Besides morpholine, the strain utilized pyrrolidine, piperidine and proposed intermediates in morpholine metabolism such as glycolate, glyoxylate and ethanolamine. Degradation of morpholine, piperidine and pyrrolidine by resting or permeabilized cells was strictly dependent on the presence of oxygen. Addition of the cytochrome-P450-specific inhibitor metyrapone to the growth medium resulted in a significantly decreased growth rate if these cyclic amines were used as a substrate. Carbon monoxide difference spectra of crude extracts from cells grown on these substrates compared to spectra obtained for extracts of succinate-grown cells indicated that cytochrome P450 is specifically expressed during growth on the cyclic amines. These data indicated that a cytochrome-P450-dependent monooxygenase is involved in the degradation of the three cyclic amines.

  1. Cytochrome c oxidase deficiency accelerates mitochondrial apoptosis by activating ceramide synthase 6.

    Science.gov (United States)

    Schüll, S; Günther, S D; Brodesser, S; Seeger, J M; Tosetti, B; Wiegmann, K; Pongratz, C; Diaz, F; Witt, A; Andree, M; Brinkmann, K; Krönke, M; Wiesner, R J; Kashkar, H

    2015-03-12

    Although numerous pathogenic changes within the mitochondrial respiratory chain (RC) have been associated with an elevated occurrence of apoptosis within the affected tissues, the mechanistic insight into how mitochondrial dysfunction initiates apoptotic cell death is still unknown. In this study, we show that the specific alteration of the cytochrome c oxidase (COX), representing a common defect found in mitochondrial diseases, facilitates mitochondrial apoptosis in response to oxidative stress. Our data identified an increased ceramide synthase 6 (CerS6) activity as an important pro-apoptotic response to COX dysfunction induced either by chemical or genetic approaches. The elevated CerS6 activity resulted in accumulation of the pro-apoptotic C16 : 0 ceramide, which facilitates the mitochondrial apoptosis in response to oxidative stress. Accordingly, inhibition of CerS6 or its specific knockdown diminished the increased susceptibility of COX-deficient cells to oxidative stress. Our results provide new insights into how mitochondrial RC dysfunction mechanistically interferes with the apoptotic machinery. On the basis of its pivotal role in regulating cell death upon COX dysfunction, CerS6 might potentially represent a novel target for therapeutic intervention in mitochondrial diseases caused by COX dysfunction.

  2. Mutant and wild-type alpha-synuclein interact with mitochondrial cytochrome C oxidase.

    Science.gov (United States)

    Elkon, Hanock; Don, Jermy; Melamed, Eldad; Ziv, Ilan; Shirvan, Anat; Offen, Daniel

    2002-06-01

    Alpha-synuclein, a presynaptic protein, was found to be the major component in the Lewy bodies (LB) in both inherited and sporadic Parkinson's disease (PD). Furthermore, rare mutations of alpha-synuclein cause autosomal-dominant PD. However, it is unknown how alpha-synuclein is involved in the pathogenesis of nigral degeneration in PD. In this study, we examine the protein-protein interactions of wild-type and mutant (A53T) a-synuclein with adult human brain cDNA expression library using the yeast two-hybrid technique. We found that both normal and mutant alpha-synuclein specifically interact with the mitochondrial complex IV enzyme, cytochrome C oxidase (COX). Wild-type and mutant alpha-synuclein genes were further fused with c-Myc tag and translated in rabbit reticulocyte lysate. Using anti-c-Myc antibody, we demonstrated that both wild-type and mutant alpha-synuclein, coimmunoprecipitated with COX. We also showed that potassium cyanide, a selective COX inhibitor, synergistically enhanced the sensitivity of SH-SY5Y neuroblastoma cells to dopamine-induced cell death. In conclusion, we found specific protein-protein interactions of alpha-synuclein, a major LB protein, to COX, a key enzyme of the mithochondrial respiratory system. This interaction suggests that alpha-synuclein aggregation may contribute to enhance the mitochondrial dysfunction, which might be a key factor in the pathogenesis of PD.

  3. Effects of Pristane on Cytochrome P450 Isozyme Expression in Rat Tissues

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    Marvin A. Cuchens

    2005-04-01

    Full Text Available Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP isozymes (CYP1A1, CYP1A2 and CYP2B, were employed to examine the effect(s of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

  4. Cardiolipin linoleic acid content and mitochondrial cytochrome c oxidase activity are associated in rat skeletal muscle.

    Science.gov (United States)

    Fajardo, Val Andrew; McMeekin, Lauren; Saint, Caitlin; LeBlanc, Paul J

    2015-04-01

    Cardiolipin (CL) is an inner-mitochondrial membrane phospholipid that is important for optimal mitochondrial function. Specifically, CL and CL linoleic (18:2ω6) content are known to be positively associated with cytochrome c oxidase (COX) activity. However, this association has not been examined in skeletal muscle. In this study, rats were fed high-fat diets with a naturally occurring gradient in linoleic acid (coconut oil [CO], 5.8%; flaxseed oil [FO], 13.2%; safflower oil [SO], 75.1%) in an attempt to alter both mitochondrial CL fatty acyl composition and COX activity in rat mixed hind-limb muscle. In general, mitochondrial membrane lipid composition was fairly resistant to dietary treatments as only modest changes in fatty acyl composition were detected in CL and other major mitochondrial phospholipids such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE). As a result of this resistance, CL 18:2ω6 content was not different between the dietary groups. Consistent with the lack of changes in CL 18:2ω6 content, mitochondrial COX activity was also not different between the dietary groups. However, correlational analysis using data obtained from rats across the dietary groups showed a significant relationship (p = 0.009, R(2) = 0.21). Specifically, our results suggest that CL 18:2ω6 content may positively influence mitochondrial COX activity thereby making this lipid molecule a potential factor related to mitochondrial health and function in skeletal muscle.

  5. Cytochrome c oxidase-intermediate fibres: importance in understanding the pathogenesis and treatment of mitochondrial myopathy.

    Science.gov (United States)

    Murphy, Julie L; Ratnaike, Thiloka E; Shang, Ersong; Falkous, Gavin; Blakely, Emma L; Alston, Charlotte L; Taivassalo, Tanja; Haller, Ronald G; Taylor, Robert W; Turnbull, Doug M

    2012-08-01

    An important diagnostic muscle biopsy finding in patients with mitochondrial DNA disease is the presence of respiratory-chain deficient fibres. These fibres are detected as cytochrome c oxidase-deficient following a sequential cytochrome c oxidase-succinate dehydrogenase reaction, often in a mosaic pattern within a population of cytochrome c oxidase-normal fibres. Detailed analysis of muscle biopsies from patients with various mitochondrial DNA defects shows that a spectrum of deficiency exists, as there are a large number of fibres which do not correspond to being either completely cytochrome c oxidase-normal (brown staining) or cytochrome c oxidase-deficient (blue staining). We have used a combination of histochemical and immunocytochemical techniques to show that a population of cytochrome c oxidase-intermediate reacting fibres are a gradation between normal and deficient fibres. We show that cytochrome c oxidase-intermediate fibres also have different genetic characteristics in terms of amount of mutated and wild-type mtDNA, and as such, may represent an important transition between respiratory normal and deficient fibres. Assessing changes in intermediate fibres will be crucial to evaluating the responses to treatment and in particular to exercise training regimes in patients with mitochondrial DNA disease.

  6. The interplay between tubulins and P450 cytochromes during Plasmodium berghei invasion of Anopheles gambiae midgut.

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    Rute C Félix

    Full Text Available BACKGROUND: Plasmodium infection increases the oxidative stress inside the mosquito, leading to a significant alteration on transcription of Anopheles gambiae detoxification genes. Among these detoxification genes several P450 cytochromes and tubulins were differently expressed, suggesting their involvement in the mosquito's response to parasite invasion. P450 cytochromes are usually involved in the metabolism and detoxification of several compounds, but are also regulated by several pathogens, including malaria parasite. Tubulins are extremely important as components of the cytoskeleton, which rearrangement functions as a response to malaria parasite invasion. METHODOLOGY/PRINCIPAL FINDINGS: Gene silencing methods were used to uncover the effects of cytochrome P450 reductase, tubulinA and tubulinB silencing on the A. gambiae response to Plasmodium berghei invasion. The role of tubulins in counter infection processes was also investigated by inhibiting their effect. Colchicine, vinblastine and paclitaxel, three different tubulin inhibitors were injected into A. gambiae mosquitoes. Twenty-four hours post injection these mosquitoes were infected with P. berghei through a blood meal from infected CD1 mice. Cytochrome P450 gene expression was measured using RT-qPCR to detect differences in cytochrome expression between silenced, inhibited and control mosquitoes. Results showed that cytochrome P450 reductase silencing, as well as tubulin (A and B silencing and inhibition affected the efficiency of Plasmodium infection. Silencing and inhibition also affected the expression levels of cytochromes P450. CONCLUSIONS: Our results suggest the existence of a relationship between tubulins and P450 cytochromes during A. gambiae immune response to P. berghei invasion. One of the P450 cytochromes in this study, CYP6Z2, stands out as the potential link in this association. Further work is needed to fully understand the role of tubulin genes in the response to

  7. A cytochrome c mutant with high electron transfer and antioxidant activities but devoid of apoptogenic effect.

    Science.gov (United States)

    Abdullaev, Ziedulla Kh; Bodrova, Marina E; Chernyak, Boris V; Dolgikh, Dmitry A; Kluck, Ruth M; Pereverzev, Mikhail O; Arseniev, Alexander S; Efremov, Roman G; Kirpichnikov, Mikhail P; Mokhova, Elena N; Newmeyer, Donald D; Roder, Heinrich; Skulachev, Vladimir P

    2002-01-01

    A cytochrome c mutant lacking apoptogenic function but competent in electron transfer and antioxidant activities has been constructed. To this end, mutant species of horse and yeast cytochromes c with substitutions in the N-terminal alpha-helix or position 72 were obtained. It was found that yeast cytochrome c was much less effective than the horse protein in activating respiration of rat liver mitoplasts deficient in endogenous cytochrome c as well as in inhibition of H(2)O(2) production by the initial segment of the respiratory chain of intact rat heart mitochondria. The major role in the difference between the horse and yeast proteins was shown to be played by the amino acid residue in position 4 (glutamate in horse, and lysine in yeast; horse protein numbering). A mutant of the yeast cytochrome c containing K4E and some other "horse" modifications in the N-terminal alpha-helix, proved to be (i) much more active in electron transfer and antioxidant activity than the wild-type yeast cytochrome c and (ii), like the yeast cytochrome c, inactive in caspase stimulation, even if added in 400-fold excess compared with the horse protein. Thus this mutant seems to be a good candidate for knock-in studies of the role of cytochrome c-mediated apoptosis, in contrast with the horse K72R, K72G, K72L and K72A mutant cytochromes that at low concentrations were less active in apoptosis than the wild-type, but were quite active when the concentrations were increased by a factor of 2-12. PMID:11879204

  8. NADH:Cytochrome b5 Reductase and Cytochrome b5 Can Act as Sole Electron Donors to Human Cytochrome P450 1A1-Mediated Oxidation and DNA Adduct Formation by Benzo[a]pyrene.

    Science.gov (United States)

    Stiborová, Marie; Indra, Radek; Moserová, Michaela; Frei, Eva; Schmeiser, Heinz H; Kopka, Klaus; Philips, David H; Arlt, Volker M

    2016-08-15

    Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after activation by cytochrome P450 (P450). Here, we investigated whether NADH:cytochrome b5 reductase (CBR) in the presence of cytochrome b5 can act as sole electron donor to human P450 1A1 during BaP oxidation and replace the canonical NADPH:cytochrome P450 reductase (POR) system. We also studied the efficiencies of the coenzymes of these reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of CBR, to mediate BaP oxidation. Two systems containing human P450 1A1 were utilized: human recombinant P450 1A1 expressed with POR, CBR, epoxide hydrolase, and cytochrome b5 in Supersomes and human recombinant P450 1A1 reconstituted with POR and/or with CBR and cytochrome b5 in liposomes. BaP-9,10-dihydrodiol, BaP-7,8-dihydrodiol, BaP-1,6-dione, BaP-3,6-dione, BaP-9-ol, BaP-3-ol, a metabolite of unknown structure, and two BaP-DNA adducts were generated by the P450 1A1-Supersomes system, both in the presence of NADPH and in the presence of NADH. The major BaP-DNA adduct detected by (32)P-postlabeling was characterized as 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP (assigned adduct 1), while the minor adduct is probably a guanine adduct derived from 9-hydroxy-BaP-4,5-epoxide (assigned adduct 2). BaP-3-ol as the major metabolite, BaP-9-ol, BaP-1,6-dione, BaP-3,6-dione, an unknown metabolite, and adduct 2 were observed in the system using P450 1A1 reconstituted with POR plus NADPH. When P450 1A1 was reconstituted with CBR and cytochrome b5 plus NADH, BaP-3-ol was the predominant metabolite too, and an adduct 2 was also generated. Our results demonstrate that the NADH/cytochrome b5/CBR system can act as the sole electron donor both for the first and second reduction of P450 1A1 during the oxidation of BaP in vitro. They suggest that NADH-dependent CBR can replace NADPH-dependent POR in the P450 1A1-catalyzed metabolism of BaP.

  9. Childhood encephalomyopathy with cytochrome c oxidase deficiency, ataxia, muscle wasting, and mental impairment.

    Science.gov (United States)

    Angelini, C; Bresolin, N; Pegolo, G; Bet, L; Rinaldo, P; Trevisan, C; Vergani, L

    1986-08-01

    The son of third cousins was normal until age 2 when he had difficulty walking. At age 8 there was limb weakness, ataxia, loss of tendon reflexes, dislalia, and he was mildly retarded. During fasting, urinary organic acid excretion was abnormally high. Cytochrome c oxidase activity in muscle was 7% of the normal mean. The enzyme in platelets was 16% of controls with a decreased cytochrome aa3 peak. These data suggest an autosomal recessive transmission of this variant of cytochrome c oxidase deficiency.

  10. Purification and characterization of the cytochrome oxidase from alkalophilic Bacillus firmus RAB.

    OpenAIRE

    Kitada, M; Krulwich, T A

    1984-01-01

    A cytochrome oxidase was purified 52-fold from membranes of alkalophilic Bacillus firmus RAB by extraction with Triton X-100, ion-exchange and hydroxyapatite chromatography, and gel filtration. On denaturing gels, the purified enzyme dissociated into two subunits of 56,000 and 40,000 Mr as well as a cytochrome c with an Mr of approximately 14,000. Heme contents calculated for an enzyme with a molecular weight of 110,000 were found to be 2 mol of heme a and 1 mol of heme c per mol of cytochrom...

  11. The Cytochrome bd Oxidase of Porphyromonas gingivalis Contributes to Oxidative Stress Resistance and Dioxygen Tolerance.

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    Julia Leclerc

    Full Text Available Porphyromonas gingivalis is an etiologic agent of periodontal disease in humans. The disease is associated with the formation of a mixed oral biofilm which is exposed to oxygen and environmental stress, such as oxidative stress. To investigate possible roles for cytochrome bd oxidase in the growth and persistence of this anaerobic bacterium inside the oral biofilm, mutant strains deficient in cytochrome bd oxidase activity were characterized. This study demonstrated that the cytochrome bd oxidase of Porphyromonas gingivalis, encoded by cydAB, was able to catalyse O2 consumption and was involved in peroxide and superoxide resistance, and dioxygen tolerance.

  12. Cytochrome c binding to Apaf-1: The effects of dATP and ionic strength

    OpenAIRE

    Purring-Koch, Cherie; McLendon, George

    2000-01-01

    In the apoptosis pathway in mammals, cytochrome c and dATP are critical cofactors in the activation of caspase 9 by Apaf-1. Until now, the detailed sequence of events in which these cofactors interact has been unclear. Here, we show through fluorescence polarization experiments that cytochrome c can bind to Apaf-1 in the absence of dATP; when dATP is added to the cytochrome c·Apaf-1 complex, further assembly occurs to produce the apoptosome. These findings, along w...

  13. Sensitive cardiac troponins and N-terminal pro-B-type natriuretic peptide in stable coronary artery disease: correlation with left ventricular function as assessed by myocardial strain.

    Science.gov (United States)

    Smedsrud, Marit Kristine; Gravning, Jørgen; Omland, Torbjørn; Eek, Christian; Mørkrid, Lars; Skulstad, Helge; Aaberge, Lars; Bendz, Bjørn; Kjekshus, John; Edvardsen, Thor

    2015-06-01

    N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponins (cTns) measured with sensitive assays provide strong prognostic information in patients with stable coronary artery disease. However, the relationship between these biomarkers and myocardial contractile function, as well as infarct size, in this patient group, remains to be defined. The study population consisted of 160 patients referred to a follow-up echocardiography scheduled 1 year after coronary revascularization. Concentrations of NT-proBNP, high-sensitive cTnT (hs-cTnT) and sensitive cTnI assays were assessed. Left ventricular function was measured as global peak systolic longitudinal strain by speckle tracking echocardiography and infarct size was assessed by late-enhancement MRI. NT-proBNP and sensitive cTnI levels were significantly associated with left ventricular function by peak systolic strain (R-values 0.243 and 0.228, p = 0.002 and 0.004) as well as infarct size (R-values 0.343 and 0.366, p = 0.014 and p = 0.008). In contrast, hs-cTnT did not correlate with left ventricular function (R = 0.095, p = 0.231) and only marginally with infarct size (R = 0.237, p = 0.094). NT-proBNP and sensitive cTnI levels correlate with left ventricular function and infarct size in patients with stable coronary artery disease after revascularization. As opposed to hs-cTnT, NT-proBNP and cTnI seem to be indicators of incipient myocardial dysfunction and the extent of myocardial necrosis.

  14. Increased DNA methylation of scavenger receptor class B type I contributes to inhibitory effects of prenatal caffeine ingestion on cholesterol uptake and steroidogenesis in fetal adrenals

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dong-Mei; He, Zheng; Ma, Liang-Peng; Wang, Lin-Long [Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071 (China); Ping, Jie, E-mail: pingjie@whu.edu.cn [Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071 (China); Hubei Provincial Key Laboratory of Developmentally Originated Diseases, Wuhan 430071 (China); Research Center of Food and Drug Evaluation, Wuhan University, Wuhan 430071 (China); Wang, Hui [Department of Pharmacology, Wuhan University School of Basic Medical Sciences, Wuhan 430071 (China); Hubei Provincial Key Laboratory of Developmentally Originated Diseases, Wuhan 430071 (China); Research Center of Food and Drug Evaluation, Wuhan University, Wuhan 430071 (China)

    2015-06-01

    Steroid hormones synthesized from cholesterol in the fetal adrenal are crucial for fetal development. We have observed the inhibited fetal adrenal corticosterone synthesis and increased intrauterine growth retardation (IUGR) rate in rats under prenatal caffeine ingestion. The aim of this study is to evaluate the effects of prenatal caffeine ingestion on cholesterol supply in fetal adrenal steroidogenesis in rats and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were treated with 60 mg/kg·d caffeine from gestational day (GD) 7 to GD17. Histological changes of fetal adrenals and increased IUGR rates were observed in the caffeine group. There were significantly decreased steroid hormone contents and cholesterol supply in caffeine-treated fetal adrenals. Data from the gene expression array suggested that prenatal caffeine ingestion caused increased expression of genes related to DNA methylation and decreased expression of genes related to cholesterol uptake. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that scavenger receptor class B type I (SR-BI) may play an important role in caffeine-induced cholesterol supply deficiency. Moreover, real-time RT-PCR and immunohistochemical detection certified the inhibitory effects of caffeine on both mRNA expression and protein expression of SR-BI in the fetal adrenal. And the increased DNA methylation frequency in the proximal promoter of SR-BI was confirmed by bisulfite-sequencing PCR. In conclusion, prenatal caffeine ingestion can induce DNA hypermethylation of the SR-BI promoter in the rat fetal adrenal. These effects may lead to decreased SR-BI expression and cholesterol uptake, which inhibits steroidogenesis in the fetal adrenal. - Highlights: • Prenatal caffeine ingestion inhibits steroid hormone production in the fetal adrenal. • Prenatal caffeine ingestion inhibits cholesterol uptake in the fetal adrenal. • Prenatal caffeine

  15. Hormone therapy with tamoxifen reduces plasma levels of NT-B-type natriuretic peptide but does not change ventricular ejection fraction after chemotherapy in women with breast cancer

    Directory of Open Access Journals (Sweden)

    F.B. Silva

    2015-02-01

    Full Text Available The objective of this study was to evaluate the effect of tamoxifen on the plasma concentration of NT-pro-B-type natriuretic peptide (NT-proBNP in women undergoing chemotherapy for breast cancer and to correlate changes in NT-proBNP with the left ventricular ejection fraction (LVEF. Over a period of 12 months, we followed 60 women with a diagnosis of breast cancer. The patients were separated into a group that received only chemotherapy (n=23, a group that received chemotherapy + tamoxifen (n=21, and a group that received only tamoxifen (n=16. Plasma levels of NT-proBNP were assessed at 0 (T0, 6 (T6, and 12 (T12 months of treatment, and echocardiography data were assessed at T0 and T12. Plasma NT-proBNP levels were increased in the chemotherapy-only group at T6 and T12, whereas elevated NT-proBNP levels were only found at T6 in the chemotherapy + tamoxifen group. At T12, the chemotherapy + tamoxifen group exhibited a significant reduction in the peptide to levels similar to the group that received tamoxifen alone. The chemotherapy-only group exhibited a significant decrease in LVEF at T12, whereas the chemotherapy + tamoxifen and tamoxifen-only groups maintained levels similar to those at the beginning of treatment. Treatment with tamoxifen for 6 months after chemotherapy significantly reduced the plasma levels of NT-proBNP and did not change LVEF in women with breast cancer.

  16. High N-terminal pro-B-type natriuretic peptide levels are associated with reduced heart rate variability in acute myocardial infarction.

    Directory of Open Access Journals (Sweden)

    Luc Lorgis

    Full Text Available AIM: We investigated the relationships between the autonomic nervous system, as assessed by heart rate variability (HRV and levels of N-terminal Pro-B-type Natriuretic Peptide (Nt-proBNP in patients with acute myocardial infarction (MI. METHODS AND RESULTS: The mean of standard deviation of RR intervals (SDNN, the percentage of RR intervals with >50 ms variation (pNN50, square root of mean squared differences of successive RR intervals (rMSSD, and frequency domain parameters (total power (TP, high frequency and low frequency power ratio (LF/HF were assessed by 24 h Holter ECG monitoring. 1018 consecutive patients admitted <24 h for an acute MI were included. Plasma Nt-proBNP (Elecsys, Roche was measured from blood samples taken on admission. The median (IQR Nt-proBNP level was 681(159-2432 pmol/L. Patients with the highest quartile of Nt-proBNP were older, with higher rate of risk factors and lower ejection fraction. The highest Nt-proBNP quartile group had the lowest SDNN, LF/HF and total power but similar pNN50 and rMSSD levels. Nt-proBNP levels correlated negatively with SDNN (r = -0.19, p<0.001, LF/HF (r = -0.37, p<0.001, and LF (r = -0.29, p<0.001 but not HF (r = -0.043, p = 0.172. Multiple regression analysis showed that plasma propeptide levels remained predictive of LF/HF (B(SE = -0.065(0.015, p<0.001, even after adjustment for confounders. CONCLUSIONS: In conclusion, our population-based study highlights the importance of Nt-proBNP levels to predict decreased HRV after acute MI.

  17. Utilization of n-alkanes by a newly isolated strain of Acinetobacter venetianus: the role of two AlkB-type alkane hydroxylases.

    Science.gov (United States)

    Throne-Holst, Mimmi; Markussen, Sidsel; Winnberg, Asgeir; Ellingsen, Trond E; Kotlar, Hans-Kristian; Zotchev, Sergey B

    2006-09-01

    A bacterial strain capable of utilizing n-alkanes with chain lengths ranging from decane (C10H22) to tetracontane (C40H82) as a sole carbon source was isolated using a system for screening microorganisms able to grow on paraffin (mixed long-chain n-alkanes). The isolate, identified according to its 16S rRNA sequence as Acinetobacter venetianus, was designated A. venetianus 6A2. Two DNA fragments encoding parts of AlkB-type alkane hydroxylase homologues, designated alkMa and alkMb, were polymerase chain reaction-amplified from the genome of A. venetianus 6A2. To study the roles of these two alkM paralogues in n-alkane utilization in A. venetianus 6A2, we constructed alkMa, alkMb, and alkMa/alkMb disruption mutants. Studies on the growth patterns of the disruption mutants using n-alkanes with different chain lengths as sole carbon source demonstrated central roles for the alkMa and alkMb genes in utilization of C10 to C18 n-alkanes. Comparative analysis of these patterns also suggested different substrate preferences for AlkMa and AlkMb in n-alkane utilization. Because both single and double mutants were able to grow on n-alkanes with chain lengths of C20 and longer, we concluded that yet another enzyme(s) for the utilization of these n-alkanes must exist in A. venetianus 6A2.

  18. N-Terminal Pro-B Type Natriuretic Peptide as a Marker of Bronchopulmonary Dysplasia or Death in Very Preterm Neonates: A Cohort Study.

    Directory of Open Access Journals (Sweden)

    Anna Sellmer

    Full Text Available Bronchopulmonary dysplasia (BPD is a serious complication of preterm birth. Plasma N-terminal pro-B type natriuretic peptide (NT-proBNP has been suggested as a marker that may predict BPD within a few days after birth.To investigate the association between NT-proBNP day three and bronchopulmonary dysplasia (BPD or death and further to assess the impact of patent ductus arteriosus (PDA on this association in neonates born before 32 gestational weeks.A cohort study of 183 neonates born before 32 gestational weeks consecutively admitted to the Neonatal Intensive Care Unit, Aarhus University Hospital, Denmark. On day three plasma samples were collected and echocardiography carried out. NT-proBNP was measured by routine immunoassays. The combined outcome BPD or death was assessed at 36 weeks of postmenstrual age. Receiver operator characteristic (ROC analysis was performed to determine the discrimination ability of NT-proBNP by the natural log continuous measure to recognize BPD or death. The association of BPD or death was assessed in relation to natural log NT-proBNP levels day three.The risk of BPD or death increased 1.7-fold with one unit increase of natural log NT-proBNP day three when adjusted for gestational age at birth (OR = 1.7, 95% CI 1.3; 2.3. The association was found both in neonates with and without a PDA. Adjusting for GA, PDA diameter, LA:Ao-ratio, or early onset sepsis did not change the estimate.We found NT-proBNP to be associated with BPD or death in very preterm neonates. This association was not only explained by the PDA. We speculate that NT-proBNP may help the identification of neonates at risk of BPD as early as postnatal day three.

  19. Model-based cost-effectiveness analysis of B-type natriuretic peptide-guided care in patients with heart failure

    Science.gov (United States)

    Mohiuddin, Syed; Reeves, Barnaby; Pufulete, Maria; Maishman, Rachel; Dayer, Mark; Macleod, John; McDonagh, Theresa; Purdy, Sarah; Rogers, Chris; Hollingworth, William

    2016-01-01

    Objective Monitoring B-type natriuretic peptide (BNP) to guide pharmacotherapy might improve survival in patients with heart failure with reduced ejection fraction (HFrEF) or preserved ejection fraction (HFpEF). However, the cost-effectiveness of BNP-guided care is uncertain and guidelines do not uniformly recommend it. We assessed the cost-effectiveness of BNP-guided care in patient subgroups defined by age and ejection fraction. Methods We used a Markov model with a 3-month cycle length to estimate the lifetime health service costs, quality-adjusted life years (QALYs) and incremental net monetary benefits (iNMBs) of BNP-guided versus clinically guided care in 3 patient subgroups: (1) HFrEF patients HFpEF patients HFpEF aged ≥75 years. We used individual patient data meta-analyses and linked primary care, hospital and mortality data to inform the key model parameters. We performed probabilistic analysis to assess the uncertainty in model results. Results In younger patients (HFpEF (£3155 (−£10 307 to £11 613)) and older patients (≥75 years) with HFrEF (£2267 (−£1524 to £6074)). BNP-guided care remained cost-effective in the sensitivity analyses, albeit the results were sensitive to assumptions on its sustained effect. Conclusions We found strong evidence that BNP-guided care is a cost-effective alternative to clinically guided care in younger patients with HFrEF. It is potentially cost-effective in younger patients with HFpEF and older patients with HFrEF, but more evidence is required, particularly with respect to the frequency, duration and BNP target for monitoring. Cost-effectiveness results from trials in specialist settings cannot be generalised to primary care. PMID:28031211

  20. MODELING OF BONE FRAGMENTS FIXATION WITH AN EXTERNAL FIXATION DEVICE FOR BILATERAL ROTATION UNSTABLE PELVIC INJURIES B TYPE ACCORDING TO AO/ASIF CLASSIFICATION

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    V. G. Vinogradov

    2014-01-01

    Full Text Available Objective: to determine the stability of bone fragments fixation with an external fixation device in the simulation of bilateral partly unstable pelvic injuries of B type according to AO/ASIF classification and to identify the role of different fixation elements in the stability of fixation. Material and methods: the study was performed on the finite element model of a system “an external fixation device - pelvis” developed for a software package MSCNastran. Formation of a fracture of pubic and ischial pelvic bones was accomplished by means of rupture in the finite element network and decrease of elasticity modulus in the ilio-sacral joint on both sides up to 35 mm at the site of a fracture. Loads were carried on top of the body of the first sacral vertebra with a force of 500H.The second area of application of the load was from the bottom-up on the acetabular roof with a force of 250H. In this study the effect of different elements of an external fixation device on the stiffness of bone fragments fixation was evaluated. Symmetrical elements were removed both separately and together. As a result, the stiffness of a system decreased and the displacement at the fracture site increased. Conclusion: in a model of partly stable pelvic injuries accompanied by general rotation instability in the horizontal and sagittal planes to 35 mm, an external fixation device provided high stability of bone fragments (to 3 mm due to introduction of bone rods in the iliac wings with the obligatory introduction of the rod in the vertical branches of pubic bones and strengthening the anterior lower bar between the subsystems. What is more, installing the anterior upper bar or introduction of bone rods in the bodies of iliac bone are not necessary.

  1. Postreplication Roles of the Brucella VirB Type IV Secretion System Uncovered via Conditional Expression of the VirB11 ATPase

    Science.gov (United States)

    Smith, Erin P.; Miller, Cheryl N.; Child, Robert; Cundiff, Jennifer A.

    2016-01-01

    ABSTRACT Brucella abortus, the bacterial agent of the worldwide zoonosis brucellosis, primarily infects host phagocytes, where it undergoes an intracellular cycle within a dedicated membrane-bound vacuole, the Brucella-containing vacuole (BCV). Initially of endosomal origin (eBCV), BCVs are remodeled into replication-permissive organelles (rBCV) derived from the host endoplasmic reticulum, a process that requires modulation of host secretory functions via delivery of effector proteins by the Brucella VirB type IV secretion system (T4SS). Following replication, rBCVs are converted into autophagic vacuoles (aBCVs) that facilitate bacterial egress and subsequent infections, arguing that the bacterium sequentially manipulates multiple cellular pathways to complete its cycle. The VirB T4SS is essential for rBCV biogenesis, as VirB-deficient mutants are stalled in eBCVs and cannot mediate rBCV biogenesis. This has precluded analysis of whether the VirB apparatus also drives subsequent stages of the Brucella intracellular cycle. To address this issue, we have generated a B. abortus strain in which VirB T4SS function is conditionally controlled via anhydrotetracycline (ATc)-dependent complementation of a deletion of the virB11 gene encoding the VirB11 ATPase. We show in murine bone marrow-derived macrophages (BMMs) that early VirB production is essential for optimal rBCV biogenesis and bacterial replication. Transient expression of virB11 prior to infection was sufficient to mediate normal rBCV biogenesis and bacterial replication but led to T4SS inactivation and decreased aBCV formation and bacterial release, indicating that these postreplication stages are also T4SS dependent. Hence, our findings support the hypothesis of additional, postreplication roles of type IV secretion in the Brucella intracellular cycle. PMID:27899503

  2. Precise Magnetic Structures of Hard Ferromagnets of ND2FE14B Type as Determined at Low Temperature from Single Crystal Neutron Diffraction

    Science.gov (United States)

    Wolfers, P.; Bacmann, M.; Fruchart, D.

    2000-09-01

    The main constituent of the hard magnet materials Nd-Fe-B is the prototype of a new ferromagnet series, the Nd2Fe14B type (Space Group P42/nmm). Such compounds are characterised by high magnetocrystalline anisotropy parameters, those of rare earth origin being several times higher than the contribution of the iron subblattices. In many cases, these two contributions exhibit markedly different thermal behaviours, resulting in spin rotation phenomena or (and) lowering of the crystalline and the magnetic symmetry from the tetragonal high temperature state. Low temperature very precise studies on selected compounds of the series R2Fe14B with R = Nd, Ho, Er and Y, were undertaken by using neutron four circle diffractometry on single crystals. When temperature is lowered, the two first compounds exhibit a continuous spin reorientation within the [110] plane from the c-axis at high temperature towards an intermediate direction. The Er compound presents a first order transition around 350K where the resulting magnetisation first order rotates from the c-axis a high temperature to the a basal plane direction at low temperature. The last one compound remains c-easy axis in the whole temperature range. From our neutron diffraction experiments, lowering of the crystal symmetry to monoclinic (orthorhombic) space groups was precisely measured for the two first (third) samples. Besides marked deviations to collinearity affect the different sublattice magnetisations. Yet, these well marked phenomena have not been accounted for in the hundert experimental and theoretical analysis dedicated to the series. However, our results are in good agreement with a detailed 57Fe Mössbauer spectroscopy analysis of the Ho ternary hydrides.

  3. Inverse association of N-terminal pro-B-type natriuretic peptide with metabolic syndrome in patients with congestive heart failure.

    Directory of Open Access Journals (Sweden)

    Huai-Ren Chang

    Full Text Available BACKGROUND: Metabolic syndrome has been shown to be associated with lower levels of plasma N-terminal pro-B-type natriuretic peptide (Nt-proBNP in the general population. We sought to elucidate the relationship between Nt-proBNP and components of metabolic syndrome in patients with congestive heart failure (CHF. METHODS: Fasting blood samples were obtained from 93 patients in our institution. Plasma levels of Nt-proBNP and other biochemical data were measured. The New York Heart Association (NYHA classification system (I-IV was used to define the functional capacity of CHF. Metabolic syndrome and its components were defined using diagnostic criteria from the International Diabetes Federation. RESULTS: Forty-nine patients (52.7% had CHF. There was a positive correlation between plasma Nt-proBNP levels and NYHA functional capacity in CHF patients. Plasma Nt-proBNP levels increased significantly with each increasing NYHA class of the disease. The prevalence of metabolic syndrome in CHF patients was higher than that in patients without CHF. Most importantly, we found that plasma Nt-proBNP levels were lower in CHF patients with metabolic syndrome attributable to inverse relationships between plasma Nt-proBNP and body mass index (β = -0.297, plasma triglyceride (β = -0.286 and homeostasis model assessment of insulin resistance (HOMA-IR; β = -0.346. Fasting glucose to insulin ratio (FGIR, an insulin sensitivity index was positively associated with plasma Nt-proBNP levels (β = 0.491, and was the independent predictor of plasma Nt-proBNP levels in CHF patients. CONCLUSIONS: Plasma Nt-proBNP levels are inversely associated with metabolic syndrome in CHF patients. Reduced plasma Nt-proBNP levels in CHF patients may lead to impaired lipolysis and metabolic function, and may contribute to the development of metabolic syndrome in CHF patients.

  4. Postreplication Roles of the Brucella VirB Type IV Secretion System Uncovered via Conditional Expression of the VirB11 ATPase

    Directory of Open Access Journals (Sweden)

    Erin P. Smith

    2016-11-01

    Full Text Available Brucella abortus, the bacterial agent of the worldwide zoonosis brucellosis, primarily infects host phagocytes, where it undergoes an intracellular cycle within a dedicated membrane-bound vacuole, the Brucella-containing vacuole (BCV. Initially of endosomal origin (eBCV, BCVs are remodeled into replication-permissive organelles (rBCV derived from the host endoplasmic reticulum, a process that requires modulation of host secretory functions via delivery of effector proteins by the Brucella VirB type IV secretion system (T4SS. Following replication, rBCVs are converted into autophagic vacuoles (aBCVs that facilitate bacterial egress and subsequent infections, arguing that the bacterium sequentially manipulates multiple cellular pathways to complete its cycle. The VirB T4SS is essential for rBCV biogenesis, as VirB-deficient mutants are stalled in eBCVs and cannot mediate rBCV biogenesis. This has precluded analysis of whether the VirB apparatus also drives subsequent stages of the Brucella intracellular cycle. To address this issue, we have generated a B. abortus strain in which VirB T4SS function is conditionally controlled via anhydrotetracycline (ATc-dependent complementation of a deletion of the virB11 gene encoding the VirB11 ATPase. We show in murine bone marrow-derived macrophages (BMMs that early VirB production is essential for optimal rBCV biogenesis and bacterial replication. Transient expression of virB11 prior to infection was sufficient to mediate normal rBCV biogenesis and bacterial replication but led to T4SS inactivation and decreased aBCV formation and bacterial release, indicating that these postreplication stages are also T4SS dependent. Hence, our findings support the hypothesis of additional, postreplication roles of type IV secretion in the Brucella intracellular cycle.

  5. Cumene hydroperoxide supported demethylation of N,N-dimethylaniline by cytochrome P-450 from adrenal cortex mitochondria.

    Science.gov (United States)

    Akhrem, A A; Khatyleva SYu; Shkumatov, V M; Chashchin, V L; Kiselev, P A

    1982-01-01

    The interaction of highly purified cytochrome P-450 from bovine adrenal cortex mitochondria (cytochrome P-450scc) with N,N-dimethylaniline (DMA), aniline, N-dimethylcyclohexylamine and cumene hydroperoxide (CHP) has been investigated. The formation of complexes between cytochrome P-450scc and the above listed compounds could be demonstrated. The reaction of oxidative demethylation of DMA by cumene hydroperoxide involving cytochrome P-450scc has been carried out at 37 degrees C; the mechanism of this process is discussed. Incubation of cytochrome P-450scc with negatively charged phospholipids, phosphatidylglycerol (PG), and phosphatidylinosite (PI) exerts an inhibiting effect on the reaction of oxidative demethylation. The interaction of cytochrome P-450scc with CHP is accompanied by hemoprotein destruction in a complex biphasic way. The process of oxidative demethylation of DMA in the system of cytochrome P-450scc-CHP has been concluded to have a predominantly radical character.

  6. Hippocampal mitochondrial cytochrome C oxidase activity and gene expression in a rat model of chronic cerebral ischemia

    Institute of Scientific and Technical Information of China (English)

    Qing Zhao; Yingli Zhang; Mingming Zhao; Yu Wang; Ming Ma; Xinquan Gu; Xia Cao

    2011-01-01

    The present study established a rat model of chronic cerebral ischemia using bilateral common carotid artery permanent ligation to analyze cytochrome C oxidase activity and mRNA expression in hippocampal mitochondria.Results showed significantly decreased cytochrome C oxidase activity and cytochrome C oxidase II mRNA expression with prolonged ischemia time.Further analysis revealed five mitochondrial cytochrome C oxidase II gene mutations, two newly generated mutations, and four absent mutational sites at 1 month after cerebral ischemia, as well as three mitochondrial cytochrome C oxidase III gene mutations, including two newly generating mutations, and one disappeared mutational site at 1 month after cerebral ischemia.Results demonstrated that decreased cytochrome C oxidase gene expression and mutations, as well as decreased cytochrome C oxidase activity, resulting in energy dysmetabolism, which has been shown to be involved in the pathological process of ischemic brain injury.

  7. Metabolism of sesamin by cytochrome P450 in human liver microsomes.

    Science.gov (United States)

    Yasuda, Kaori; Ikushiro, Shinichi; Kamakura, Masaki; Ohta, Miho; Sakaki, Toshiyuki

    2010-12-01

    Metabolism of sesamin by cytochrome P450 (P450) was examined using yeast expression system and human liver microsomes. Saccharomyces cerevisiae cells expressing each of human P450 isoforms (CYP1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) were cultivated with sesamin, and monocatechol metabolite was observed in most of P450s. Kinetic analysis using the microsomal fractions of the recombinant S. cerevisiae cells revealed that CYP2C19 had the largest k(cat)/K(m) value. Based on the kinetic data and average contents of the P450 isoforms in the human liver, the putative contribution of P450s for sesamin metabolism was large in the order of CYP2C9, 1A2, 2C19, and 2D6. A good correlation was observed between sesamin catecholization activity and CYP2C9-specific activity in in vitro studies using 10 individual human liver microsomes, strongly suggesting that CYP2C9 is the most important P450 isoform for sesamin catecholization in human liver. Inhibition studies using each anti-P450 isoform-specific antibody confirmed that CYP2C9 was the most important, and the secondary most important P450 was CYP1A2. We also examined the inhibitory effect of sesamin for P450 isoform-specific activities and found a mechanism-based inhibition of CYP2C9 by sesamin. In contrast, no mechanism-based inhibition by sesamin was observed in CYP1A2-specific activity. Our findings strongly suggest that further studies are needed to reveal the interaction between sesamin and therapeutic drugs mainly metabolized by CYP2C9.

  8. Interrelationship Between Broadband NIRS Measurements of Cerebral Cytochrome C Oxidase and Systemic Changes Indicates Injury Severity in Neonatal Encephalopathy.

    Science.gov (United States)

    Bale, Gemma; Mitra, Subhabrata; de Roever, Isabel; Chan, Marcus; Caicedo-Dorado, Alexander; Meek, Judith; Robertson, Nicola; Tachtsidis, Ilias

    2016-01-01

    Perinatal hypoxic ischaemic encephalopathy (HIE) is associated with severe neurodevelopmental problems and mortality. There is a clinical need for techniques to provide cotside assessment of the injury extent. This study aims to use non-invasive cerebral broadband near-infrared spectroscopy (NIRS) in combination with systemic physiology to assess the severity of HIE injury. Broadband NIRS is used to measure the changes in haemodynamics, oxygenation and the oxidation state of cytochrome c oxidase (oxCCO). We used canonical correlation analysis (CCA), a multivariate statistical technique, to measure the relationship between cerebral broadband NIRS measurements and systemic physiology. A strong relationship between the metabolic marker, oxCCO, and systemic changes indicated severe brain injury; if more than 60 % of the oxCCO signal could be explained by the systemic variations, then the neurodevelopmental outcome was poor. This boundary has high sensitivity and specificity (100 and 83 %, respectively). Broadband NIRS measured concentration changes of the oxidation state of cytochrome c oxidase has the potential to become a useful cotside tool for assessment of injury severity following hypoxic ischaemic brain injury.

  9. Interethnic differences of cytochrome P450 gene polymorphisms may influence outcome of taxane therapy in Roma and Hungarian populations.

    Science.gov (United States)

    Szalai, Renata; Ganczer, Alma; Magyari, Lili; Matyas, Petra; Bene, Judit; Melegh, Bela

    2015-12-01

    Taxanes are widely used microtubule-stabilizing chemotherapeutic agents in the treatment of cancers. Several cytochrome P450 gene variants have been proven to influence taxane metabolism and therapy. The purpose of this work was to determine the distribution of genetic variations of CYP1B1, CYP2C8 and CYP3A5 genes as the first report on taxane metabolizer cytochrome P450 gene polymorphisms in Roma and Hungarian populations. A total of 397 Roma and 412 Hungarian healthy subjects were genotyped for CYP1B1 c.4326C > G, CYP2C8 c.792C > G and CYP3A5 c.6986A > G variant alleles by PCR-RFLP assay and direct sequencing. We found significant differences in the frequencies of homozygous variant genotypes of CYP1B1 4326 GG (p = 0.002) and CYP3A5 6986 GG (p Roma and Hungarian populations. Regarding minor allele frequencies, for CYP2C8 a significantly increased prevalence was found in 792G allele frequency in the Hungarian population compared to the Roma population (5.83% vs. 2.14%, p = 0.001). Our results can be used as possible predictive factors in population specific treatment algorithms to developing effective programs for a better outcome in patients treated with taxanes.

  10. B类1型清道夫受体表达调控与信号转导通路%Expression Regulation and Signal Transduction of Scavenger Receptor Class B Type 1

    Institute of Scientific and Technical Information of China (English)

    张青海; 易光辉; 李媛彬; 阮长耿

    2009-01-01

    Scavenger receptor class B type 1 (SR-B1) is a membrane glycoprotein with multiple biological functions and a high homology to scavenger receptor CD36. A variety of factors may affect SR-B1 expression at the transcription or post-transcriptional level in vivo and in vitro . PPARα/γ agonists, certain LXR agonists, LH/HCG and estrogen up-regulate the SR-B1 expression, whereas vitamin E, INFa, lipopolysaccharide, IGF-1, bile acid, PXR agonist and hyperglycemia down-regulate its expression. Angiotensin II affects regulates the expression of SR-B1 in a bidirectional manner, as the specific mechanism involved is highly complicated. As a multi-ligand-binding membrane receptor, distinct intracellular signaling events and biological effects id mediated by different ligands, for instance, HDL-activated PI3K/Akt and MAPKs signaling pathway is responsible to increase the phosphorylation of eNOS and promote the migration of endothelial cell and endothelial reconstruction. Furthermore, SR-B1 is also involved in LDL-activated p38MAPK pathway, apoptotic cells and serum amyloid. The recent progress on the understanding of SR-B1 expression regulation and signal transduction is reviewed.%B类1型清道夫受体(scavenger receptor class B type 1,SR-B1)是一种与清道夫受体CD36具有高度同源性的膜糖蛋白,其表达相对广泛且有着众多生物学作用.体内外多种因素可从转录或转录后水平对SR-B1表达进行调控:PPARα/γ激动剂、部分LXR激动剂、LH/HCG、雌激素等能上调SR-B1的表达;维生素E、INFα、脂多糖、IGF-1、胆酸、PXR激动剂及高糖水平等能下调SR-B1的表达;而血管紧张素Ⅱ则可对SR-B1的表达进行双向调节,且它们具体的调节机制复杂.SR-B1作为一种具有多配体结合特性的膜受体,不同配体与其结合后可介导细胞内不同信号事件及生物学效应,如介导HDL激活细胞内P13K/Akt及MAPK信号途径,增加内皮型一氧化氮合酶的磷酸化

  11. B型利钠肽和氮端B型利钠肽原在早产儿动脉导管未闭诊治的研究进展%The use of B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide concentrations to guide diagnosis and treatment of patent ductus arteriosus in preterm infants

    Institute of Scientific and Technical Information of China (English)

    刘颖; 周于新

    2016-01-01

    早产儿动脉导管未闭(PDA)发病率高,可引发很多并发症,但其诊治和预后判断标准仍存在争议.近期报道B型利钠肽和氮端B型利钠肽原用于早产儿血流动力学显著PDA(hsPDA)的诊断,且有助于其治疗策略的选择和对药物治疗反应的判断,但研究方法和临界值等尚未统一,笔者将国内外B型利钠肽和氮端B型利钠肽原在早产儿动脉导管未闭诊治的研究进展作一综述,为儿科临床及基础研究提供依据.%The high morbidity and compliments of patent ductus arteriosus (PDA) in preterm infants are reported,but the diagnostic and prognostic appraisal of PDA is still debatable.The B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are found efficient in diagnosis of hemodynamically significant patent ductus arteriosus (hsPDA) in preterm infants,and also helpful in therapy decisions and prediction of treatment response.However,the type of assay and cut-off values have not yet reached a consent,so that further researches are needed.

  12. Sulfite oxidase activity of cytochrome c: Role of hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Murugesan Velayutham

    2016-03-01

    Full Text Available In humans, sulfite is generated endogenously by the metabolism of sulfur containing amino acids such as methionine and cysteine. Sulfite is also formed from exposure to sulfur dioxide, one of the major environmental pollutants. Sulfite is used as an antioxidant and preservative in dried fruits, vegetables, and beverages such as wine. Sulfite is also used as a stabilizer in many drugs. Sulfite toxicity has been associated with allergic reactions characterized by sulfite sensitivity, asthma, and anaphylactic shock. Sulfite is also toxic to neurons and cardiovascular cells. Recent studies suggest that the cytotoxicity of sulfite is mediated by free radicals; however, molecular mechanisms involved in sulfite toxicity are not fully understood. Cytochrome c (cyt c is known to participate in mitochondrial respiration and has antioxidant and peroxidase activities. Studies were performed to understand the related mechanism of oxidation of sulfite and radical generation by ferric cytochrome c (Fe3+cyt c in the absence and presence of H2O2. Electron paramagnetic resonance (EPR spin trapping studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO were performed with sulfite, Fe3+cyt c, and H2O2. An EPR spectrum corresponding to the sulfite radical adducts of DMPO (DMPO-SO3- was obtained. The amount of DMPO-SO3- formed from the oxidation of sulfite by the Fe3+cyt c increased with sulfite concentration. In addition, the amount of DMPO-SO3- formed by the peroxidase activity of Fe3+cyt c also increased with sulfite and H2O2 concentration. From these results, we propose a mechanism in which the Fe3+cyt c and its peroxidase activity oxidizes sulfite to sulfite radical. Our results suggest that Fe3+cyt c could have a novel role in the deleterious effects of sulfite in biological systems due to increased production of sulfite radical. It also shows that the increased production of sulfite radical may be responsible for neurotoxicity and some of the injuries which

  13. Effects of cytochrome P450 inhibitors on the biotransformation of fluorogenic substrates by adult male rat liver microsomes and cDNA-expressed rat cytochrome P450 isoforms.

    Science.gov (United States)

    Makaji, Emilija; Trambitas, Cristina S; Shen, Pamela; Holloway, Alison C; Crankshaw, Denis J

    2010-02-01

    We have evaluated the use of a panel of six fluorogenic cytochrome P450 (CYP) substrates as a potential tool for rapid screening for global changes in CYP activity in rats under different physiological conditions. The biotransformation of 3-[2-(N,N-diethyl-N-methylammonium)ethyl]-7-methoxy-4-methylcoumarin (AMMC), 7-benzyloxy-4-(trifluoromethyl)-coumarin, 7-benzyloxyquinoline, 3-cyano-7-ethoxycoumarin, 7-methoxy-4-(trifluoromethyl)-coumarin, and 7-ethoxy-4-trifluoromethyl-coumarin by microsomes from adult male rat liver were characterized, their sensitivities to 15 putative inhibitors were determined and compared to similar experiments using nine different complementary DNA (cDNA)-expressed rat CYPs. Inhibitory profiles of the substrates in microsomes were different from each other, with some overlap, suggesting that each substrate is to some extent biotransformed by a different CYP isoform. Ketoconazole and clotrimazole were nonselective inhibitors, while ticlopidine selectively inhibited biotransformation of AMMC. CYP2A1 did not biotransform any of the substrates, and CYP2E1 was insensitive to all the inhibitors tested. Some inhibitors did not affect the biotransformation of the fluorogenic substrates by cDNA-expressed isoforms as predicted by their effects on conventional substrates, e.g., chlorzoxazone and diethyldithiocarbamate were inactive against CYP2E1, and CYP2C6 was not inhibited by sulfaphenazole. When results in microsomes and cDNA-expressed CYPs were compared, only the majority of the biotransformation of AMMC by microsomes could be assigned with full confidence to a specific CYP isoform, namely CYP2D2. Nevertheless, different inhibitory profiles of the substrates indicate that the panel will be useful for rapid functional quantification of global CYP activity in rats under different experimental conditions. Our results also demonstrate the inappropriateness of extrapolating inhibitory data between conventional and fluorogenic CYP substrates.

  14. Conjugation of cytochrome c with hydrogen titanate nanotubes: novel conformational state with implications for apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Moumita; Mazumdar, Shyamalava [Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Chatterjee, Sriparna; Das, Tanmay; Bhattacharyya, Somnath; Ayyub, Pushan, E-mail: somnath@tifr.res.in, E-mail: pushan@tifr.res.in, E-mail: shyamal@tifr.res.in [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2011-10-14

    We show that hydrogen titanate (H{sub 2}Ti{sub 3}O{sub 7}) nanotubes form strongly associated reversible nano-bio-conjugates with the vital respiratory protein, cytochrome c. Resonance Raman spectroscopy along with direct electrochemical studies indicate that in this nano-bio-conjugate, cytochrome c exists in an equilibrium of two conformational states with distinctly different formal redox potentials and coordination geometries of the heme center. The nanotube-conjugated cytochrome c also showed enhanced peroxidase activity similar to the membrane-bound protein that is believed to be an apoptosis initiator. This suggests that such a nanotube-cytochrome c conjugate may be a good candidate for cancer therapy applications.

  15. Mapping of redox state of mitochondrial cytochromes in live cardiomyocytes using Raman microspectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A; Treiman, Marek; Brazhe, Alexey R;

    2012-01-01

    This paper presents a nonivasive approach to study redox state of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] of complexes II and III in mitochondria of live cardiomyocytes by means of Raman microspectroscopy. For the first time with the proposed approach we......-shaped cardiomyocytes possess uneven distribution of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text] in cell center and periphery. Moreover, by means of Raman spectroscopy we demonstrated the decrease in the relative amounts of reduced cytochromes [Formula: see text], [Formula: see...... perform studies of rod- and round-shaped cardiomyocytes, representing different morphological and functional states. Raman mapping and cluster analysis reveal that these cardiomyocytes differ in the amounts of reduced cytochromes [Formula: see text], [Formula: see text] and [Formula: see text]. The rod...

  16. Prognostic Value of Cytochrome C and Cytokines in Acute Viral Encephalopathy

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2006-06-01

    Full Text Available Serum cytochrome c and cytokines were evaluated as prognostic predictors in 29 children (ages 9 mos to 9 yrs 11 mos with viral acute encephalopathies and multiple organ failure at Fukushima Medical University School of Medicine, Japan.

  17. High thermal stability and unique trimer formation of cytochrome c' from thermophilic Hydrogenophilus thermoluteolus.

    Science.gov (United States)

    Fujii, Sotaro; Masanari, Misa; Inoue, Hiroki; Yamanaka, Masaru; Wakai, Satoshi; Nishihara, Hirofumi; Sambongi, Yoshihiro

    2013-01-01

    Sequence analysis indicated that thermophilic Hydrogenophilus thermoluteolus cytochrome c' (PHCP) and its mesophilic homolog, Allochromatium vinosum cytochrome c' (AVCP), closely resemble each other in a phylogenetic tree of the cytochrome c' family, with 55% sequence identity. The denaturation temperature of PHCP was 87 °C, 35 °C higher than that of AVCP. Furthermore, PHCP exhibited a larger enthalpy change value during its thermal denaturation than AVCP. While AVCP was dimeric, as observed previously, PHCP was trimeric, and this was the first observation as a cytochrome c'. Dissociation of trimeric PHCP and its protein denaturation reversibly occurred at the same time in a two-state transition manner. Therefore, PHCP is enthalpically more stable than AVCP, perhaps due to its unique trimeric form, in addition to the lower number of Gly residues in its putative α-helical regions.

  18. Nanoscale charge transport in cytochrome c3/DNA network: Comparative studies between redox-active molecules

    Science.gov (United States)

    Yamaguchi, Harumasa; Che, Dock-Chil; Hirano, Yoshiaki; Suzuki, Masayuki; Higuchi, Yoshiki; Matsumoto, Takuya

    2015-09-01

    The redox-active molecule of a cytochrome c3/DNA network exhibits nonlinear current-voltage (I-V) characteristics with a threshold bias voltage at low temperature and zero-bias conductance at room temperature. I-V curves for the cytochrome c3/DNA network are well matched with the Coulomb blockade network model. Comparative studies of the Mn12 cluster, cytochrome c, and cytochrome c3, which have a wide variety of redox potentials, indicate no difference in charge transport, which suggests that the conduction mechanism is not directly related to the redox states. The charge transport mechanism has been discussed in terms of the newly-formed electronic energy states near the Fermi level, induced by the ionic interaction between redox-active molecules with the DNA network.

  19. Importance of c-Type cytochromes for U(VI reduction by Geobacter sulfurreducens

    Directory of Open Access Journals (Sweden)

    Leang Ching

    2007-03-01

    Full Text Available Abstract Background In order to study the mechanism of U(VI reduction, the effect of deleting c-type cytochrome genes on the capacity of Geobacter sulfurreducens to reduce U(VI with acetate serving as the electron donor was investigated. Results The ability of several c-type cytochrome deficient mutants to reduce U(VI was lower than that of the wild type strain. Elimination of two confirmed outer membrane cytochromes and two putative outer membrane cytochromes significantly decreased (ca. 50–60% the ability of G. sulfurreducens to reduce U(VI. Involvement in U(VI reduction did not appear to be a general property of outer membrane cytochromes, as elimination of two other confirmed outer membrane cytochromes, OmcB and OmcC, had very little impact on U(VI reduction. Among the periplasmic cytochromes, only MacA, proposed to transfer electrons from the inner membrane to the periplasm, appeared to play a significant role in U(VI reduction. A subpopulation of both wild type and U(VI reduction-impaired cells, 24–30%, accumulated amorphous uranium in the periplasm. Comparison of uranium-accumulating cells demonstrated a similar amount of periplasmic uranium accumulation in U(VI reduction-impaired and wild type G. sulfurreducens. Assessment of the ability of the various suspensions to reduce Fe(III revealed no correlation between the impact of cytochrome deletion on U(VI reduction and reduction of Fe(III hydroxide and chelated Fe(III. Conclusion This study indicates that c-type cytochromes are involved in U(VI reduction by Geobacter sulfurreducens. The data provide new evidence for extracellular uranium reduction by G. sulfurreducens but do not rule out the possibility of periplasmic uranium reduction. Occurrence of U(VI reduction at the cell surface is supported by the significant impact of elimination of outer membrane cytochromes on U(VI reduction and the lack of correlation between periplasmic uranium accumulation and the capacity for uranium

  20. CYP5122A1, a novel cytochrome P450 is essential for survival of Leishmania donovani.

    Directory of Open Access Journals (Sweden)

    Smriti Verma

    Full Text Available BACKGROUND: Cytochrome P450s (CYP450s are hemoproteins catalysing diverse biochemical reactions important for metabolism of xenobiotics and synthesis of physiologically important compounds such as sterols. Therefore, they are functionally important for survival of invading pathogens. One such opportunistic pathogen Leishmania donovani causes visceral leishmaniasis worldwide, which is an important public health problem due to significant disease burden. The parasite genome database, Gene DB, annotates 3 CYP450s in Leishmania, however, the functional role of cytochrome P450 enzymes in Leishmania spp. remains elusive. METHODOLOGY/PRINCIPAL FINDINGS: A CYP450-like gene cloned from Leishmania donovani was identified as a novel CYP450, the CYP5122A1. Upon co-localization with organelle specific markers, CYP5122A1 distribution was shown to be localized in the promastigote ER, mitochondria and the glycosomes. Replacement of one allele of CYP5122A1 with either neomycin or hygromycin gene by homologous recombination in Leishmania promastigotes induced substantial reduction of CYP5122A1 expression. These parasites showed impaired growth, lower mitochondrial Ca(2+ and membrane potential resulting in low ATP generation. Also, these parasites were less infective in vitro and in vivo than their wild-type counterparts as assessed by incubation of Leishmania promastigotes with macrophages in vitro as well as through administration of parasites into hamsters. The HKOs were more susceptible to drugs like miltefosine and antimony, but showed reduced sensitivity to amphotericin B. Removal of two alleles of CYP5122A1 did not allow the parasites to survive. The mutant parasites showed 3.5 times lower ergosterol level as compared to the wild-type parasites when estimated by Gas chromatography/mass spectrometry. Complementation of CYP5122A1 through episomal expression of protein by using pXG-GFP+2 vector partially rescued CYP5122A1 expression and restored ergosterol

  1. Ovariectomy modulates the response of some cytochrome P450 isozymes to lindane in the rat.

    Science.gov (United States)

    Oropeza-Hernández, L F; Sierra-Santoyo, A; Cebrián, M E; Manno, M; Albores, A

    2001-10-15

    The effect of 0, 1, 5, 25 and 50 mg/kg body weight (b.w.) lindane, administered in corn oil by gavage, on cytochrome P450 (CYP) phenotype was investigated in the liver of ovariectomized (ovx), sham operated (sham-ope) and nonovariectomized (n/ovx) adult Wistar rats. Total hepatic microsomal CYP content and the O-dealkylation of 7-ethoxy- (EROD), 7-methoxy- (MROD), 7-pentoxy- (PROD) and 7-benzyloxy-resorufin (BROD) were assayed. In addition, CYP1A1, 2B1/2B2, 2C11 and 3A2 proteins were determined by western blot using specific anti-rat antibodies. Protein bands were visualised by chemiluminescence and their intensities were compared among groups. A statistically significant, dose-dependent increase of all parameters studied was observed in all three animal groups after lindane administration. Ovx rats, however, responded differently to lindane administration than n/ovx or sham-ope animals. At the highest doses in ovx rats, the relative liver weight was more increased and the total CYP content was less increased than in n/ovx or sham-ope animals. Moreover, the degree of induction of PROD and BROD activities was higher and that of EROD activity was lower in ovx than in either n/ovx or sham-ope animals. Accordingly, CYP2B1/2B2 protein showed the largest increase in ovx rats, whereas CYP1A protein increased more in n/ovx or sham-ope animals. CYP2C11, a cytochrome predominantly expressed in males, was also more strongly induced in ovx than in n/ovx or sham-ope animals. CYP3A2 was slightly expressed in ovx but not in n/ovx non-treated rats, although the effect of induction was clearly greater in the latter. These results, overall, indicate that ovariectomy significantly affects, both qualitatively and quantitatively, CYP expression following induction by lindane and support the anti-estrogenic effect of lindane in rats. The pathophysiological and toxicological relevance of liver CYP induction by lindane and possibly other organochlorine xenobiotics in females with a lack

  2. Differential selectivity of cytochrome P450 inhibitors against probe substrates in human and rat liver microsomes

    Science.gov (United States)

    Eagling, Victoria A; Tjia, John F; Back, David J

    1998-01-01

    Aims Chemical inhibitors of cytochrome P450 (CYP) are a useful tool in defining the role of individual CYPs involved in drug metabolism. The aim of the present study was to evaluate the selectivity and rank the order of potency of a range of isoform-selective CYP inhibitors and to compare directly the effects of these inhibitors in human and rat hepatic microsomes. Methods Four chemical inhibitors of human cytochrome P450 isoforms, furafylline (CYP1A2), sulphaphenazole (CYP2C9), diethyldithiocarbamate (CYP2E1), and ketoconazole (CYP3A4) were screened for their inhibitory specificity towards CYP-mediated reactions in both human and rat liver microsomal preparations. Phenacetin O-deethylation, tolbutamide 4-hydroxylation, chlorzoxazone 6-hydroxylation and testosterone 6β-hydroxylation were monitored for enzyme activity. Results Furafylline was a potent, selective inhibitor of phenacetin O-deethylation (CYP1A2-mediated) in human liver microsomes (IC50 = 0.48 μm), but inhibited both phenacetin O-deethylation and tolbutamide 4-hydroxylation (CYP2C9-mediated) at equimolar concentrations in rat liver microsomes (IC50 = 20.8 and 24.0 μm respectively). Sulphaphenazole demonstrated selective inhibition of tolbutamide hydroxylation in human liver microsomes but failed to inhibit this reaction in rat liver microsomes. DDC demonstrated a low level of selectivity as an inhibitory probe for chlorzoxazone 6-hydroxylation (CYP2E1-mediated). DDC also inhibited testosterone 6β-hydroxylation (CYP3A-mediated) in man and rat, and tolbutamide 4-hydroxylase activity in rat. Ketoconazole was a very potent, selective inhibitor of CYP3A4 activity in human liver (IC50 = 0.04 μm). Although inhibiting CYP3A in rat liver it also inhibited all other reactions at concentrations ≤5 μm. Conclusions It is evident that CYP inhibitors do not exhibit the same selectivity in human and rat liver microsomes. This is due to differential selectivity of the inhibitors and/or differences in the CYP

  3. Kinetics and Mechanistic Studies on the Reaction between Cytochrome c and Tea Catechins

    OpenAIRE

    Lihua Wang; Elizabeth Santos; Desiree Schenk; Montserrat Rabago-Smith

    2014-01-01

    Green tea is characterized by the presence of an abundance of polyphenolic compounds, also known as catechins, including epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (EGC) and epigallocatechin gallate (EGCG). In addition to being a popular beverage, tea consumption has been suggested as a mean of chemoprevention. However, its mode of action is unclear. It was discovered that tea catechins can react with cytochrome c. When oxidized cytochrome c was mixed with catechins commonl...

  4. Redox reactions of cytochrome c facilitated by silver-imidazole complex

    Institute of Scientific and Technical Information of China (English)

    FAN, Chun-Hai; LI, Gen-Xi; ZHU, De-Xu; ZHU, Jian-Qin

    2000-01-01

    An imidazole modified silver electrode is prepared by immersing the substrate silver electrode in a 2% imidazole solution of ethanol at 50℃ for 10 min. The modified electrode is then swept in a cytochrome c solution and the modified layer takes off because the modified electrode is very unstable. Although the amount of the silver-imidazole complex is very small compared with the amount of cytochrome c in the protein solution, it greatly facilitates redox reactions involving the biomacromolecules.

  5. Cytochrome c Can Form a Well-Defined Binding Pocket for Hydrocarbons.

    Science.gov (United States)

    McClelland, Levi J; Steele, Harmen B B; Whitby, Frank G; Mou, Tung-Chung; Holley, David; Ross, J B Alexander; Sprang, Stephen R; Bowler, Bruce E

    2016-12-28

    Cytochrome c can acquire peroxidase activity when it binds to cardiolipin in mitochondrial membranes. The resulting oxygenation of cardiolipin by cytochrome c provides an early signal for the onset of apoptosis. The structure of this enzyme-substrate complex is a matter of considerable debate. We present three structures at 1.7-2.0 Å resolution of a domain-swapped dimer of yeast iso-1-cytochrome c with the detergents, CYMAL-5, CYMAL-6, and ω-undecylenyl-β-d-maltopyranoside, bound in a channel that places the hydrocarbon moieties of these detergents next to the heme. The heme is poised for peroxidase activity with water bound in place of Met80, which serves as the axial heme ligand when cytochrome c functions as an electron carrier. The hydroxyl group of Tyr67 sits 3.6-4.0 Å from the nearest carbon of the detergents, positioned to act as a relay in radical abstraction during peroxidase activity. Docking studies with linoleic acid, the most common fatty acid component of cardiolipin, show that C11 of linoleic acid can sit adjacent to Tyr67 and the heme, consistent with the oxygenation pattern observed in lipidomics studies. The well-defined hydrocarbon binding pocket provides atomic resolution evidence for the extended lipid anchorage model for cytochrome c/cardiolipin binding. Dimer dissociation/association kinetics for yeast versus equine cytochrome c indicate that formation of mammalian cytochrome c dimers in vivo would require catalysis. However, the dimer structure shows that only a modest deformation of monomeric cytochrome c would suffice to form the hydrocarbon binding site occupied by these detergents.

  6. Genetic control of a cytochrome P450 metabolism-based herbicide resistance mechanism in Lolium rigidum

    OpenAIRE

    2010-01-01

    The dynamics of herbicide resistance evolution in plants are influenced by many factors, especially the biochemical and genetic basis of resistance. Herbicide resistance can be endowed by enhanced rates of herbicide metabolism because of the activity of cytochrome P450 enzymes, although in weedy plants the genetic control of cytochrome P450-endowed herbicide resistance is poorly understood. In this study we have examined the genetic control of P450 metabolism-based herbicide resistance in a w...

  7. A predicted structure of the cytochrome c oxidase from Burkholderia pseudomallei

    OpenAIRE

    Mohd. Raih,Mohd. Firdaus; Sailan,Ahmad Tarmidi; Zamrod,Zulkeflie; Embi,Mohd. Noor; Mohamed, Rahmah

    2003-01-01

    Cytochrome c oxidase, the terminal enzyme of the respiratory chains of mitochondria and aerobic bacteria, catalyzes electron transfer from cytochrome c to molecular oxygen. The enzyme belongs to the haem-copper-containing oxidases superfamily. A recombinant plasmid carrying a 2.0 kb insert from a Burkholderia pseudomallei genomic library was subjected to automated DNA sequencing utilizing a primer walking strategy. Analysis of the 2002 bp insert revealed a 1536 bp open reading frame predicted...

  8. High stability of apo-cytochrome c' from thermophilic Hydrogenophilus thermoluteolus.

    Science.gov (United States)

    Fujii, Sotaro; Masanari, Misa; Yamanaka, Masaru; Wakai, Satoshi; Sambongi, Yoshihiro

    2014-01-01

    Apo-cytochomes c without heme are usually unstructured. Here we showed that apo-form of thermophilic Hydrogenophilus thermoluteolus cytochrome c' (PHCP) was a monomeric protein with high helix content. Apo-PHCP was thermally stable, possibly due to the hydrophobic residues and ion pairs. PHCP is the first example of a structured apo-cytochrome c', which will expand our view of hemoprotein structure formation.

  9. OmcF, a Putative c-Type Monoheme Outer Membrane Cytochrome Required for the Expression of Other Outer Membrane Cytochromes in Geobacter sulfurreducens

    OpenAIRE

    2005-01-01

    Outer membrane cytochromes are often proposed as likely agents for electron transfer to extracellular electron acceptors, such as Fe(III). The omcF gene in the dissimilatory Fe(III)-reducing microorganism Geobacter sulfurreducens is predicted to code for a small outer membrane monoheme c-type cytochrome. An OmcF-deficient strain was constructed, and its ability to reduce and grow on Fe(III) citrate was found to be impaired. Following a prolonged lag phase (150 h), the OmcF-deficient strain de...

  10. Exposure to GSM 900 MHz electromagnetic fields affects cerebral cytochrome c oxidase activity.

    Science.gov (United States)

    Ammari, Mohamed; Lecomte, Anthony; Sakly, Mohsen; Abdelmelek, Hafedh; de-Seze, René

    2008-08-19

    The world-wide and rapidly growing use of mobile phones has raised serious concerns about the biological and health-related effects of radio frequency (RF) radiation, particularly concerns about the effects of RFs upon the nervous system. The goal of this study was conducted to measure cytochrome oxidase (CO) levels using histochemical methods in order to evaluate regional brain metabolic activity in rat brain after exposure to a GSM 900 MHz signal for 45 min/day at a brain-averaged specific absorption rate (SAR) of 1.5 W/Kg or for 15 min/day at a SAR of 6 W/Kg over seven days. Compared to the sham and control cage groups, rats exposed to a GSM signal at 6 W/Kg showed decreased CO activity in some areas of the prefrontal and frontal cortex (infralimbic cortex, prelimbic cortex, primary motor cortex, secondary motor cortex, anterior cingulate cortex areas 1 and 2 (Cg1 and Cg2)), the septum (dorsal and ventral parts of the lateral septal nucleus), the hippocampus (dorsal field CA1, CA2 and CA3 of the hippocampus and dental gyrus) and the posterior cortex (retrosplenial agranular cortex, primary and secondary visual cortex, perirhinal cortex and lateral entorhinal cortex). However, the exposure to GSM at 1.5 W/Kg did not affect brain activity. Our results indicate that 6 W/Kg GSM 900 MHz microwaves may affect brain metabolism and neuronal activity in rats.

  11. Mitochondria-cytochrome C-caspase-9 cascade mediates isorhamnetin-induced apoptosis.

    Science.gov (United States)

    Lee, Hyo-Jung; Lee, Hyo-Jeong; Lee, Eun-Ok; Ko, Seong-Gyu; Bae, Hyun-Soo; Kim, Cheol-Ho; Ahn, Kyoo-Seok; Lu, Junxuan; Kim, Sung-Hoon

    2008-11-08

    Isorhamnetin is a flavanoid present in plants of the Polygonaceae family and is also an immediate metabolite of quercetin in mammals. Since the plasma level of isorhamnetin is maintained longer than quercetin, isorhamnetin may be a key metabolite to mediate the anti-tumor effect of quercetin. In the present study, we investigated the apoptotic mechanism of isorhamnetin in Lewis lung cancer (LLC) cells in vitro and established its in vivo anti-cancer efficacy. In cell culture, isorhamnetin significantly increased DNA fragmentation, and TUNEL positive apoptotic bodies and sub-G(1) apoptotic population in time- and dose-dependent manners. Western blot analyses revealed increased cleavage of caspase-3, and caspase-9 and PARP and increased cytosolic cytochrome C in isorhamnetin-treated cells. These events were accompanied by a reduced mitochondrial potential. Apoptosis was blocked by a general caspase inhibitor or the specific inhibitor of caspase-3 or -9. These in vitro results support mitochondria-dependent caspase activation to mediate isorhamnetin-induced apoptosis. Furthermore, an animal study revealed for the first time that isorhamnetin given by i.p. injection at a dose that is at least one order of magnitude lower than quercetin significantly suppressed the weights of tumors excised from LLC bearing mice. The in vivo anti-tumor efficacy was accompanied by increased TUNEL-positive and cleaved-caspase-3-positive tumor cells. Our data therefore support isorhamnetin as an active anti-cancer metabolite of quercetin in part through caspase-mediated apoptosis.

  12. Monooxygenation of small hydrocarbons catalyzed by bacterial cytochrome p450s.

    Science.gov (United States)

    Shoji, Osami; Watanabe, Yoshihito

    2015-01-01

    Cytochrome P450s (P450s) catalyze the NAD(P)H/O2-dependent monooxygenation of less reactive organic molecules under mild conditions. The catalytic activity of bacterial P450s is very high compared with P450s isolated from animals and plants, and the substrate specificity of bacterial P450s is also very high. Accordingly, their catalytic activities toward nonnative substrates are generally low especially toward small hydrocarbons. However, mutagenesis approaches have been very successful for engineering bacterial P450s for the hydroxylation of small hydrocarbons. On the other hand, "decoy" molecules, whose structures are very similar to natural substrates, can be used to trick the substrate recognition of bacterial P450s, allowing the P450s to catalyze oxidation reactions of nonnative substrates without any substitution of amino acid residues in the presence of decoy molecules. Thus, the hydroxylation of small hydrocarbons such as ethane, propane, butane and benzene can be catalyzed by P450BM3, a long-alkyl-chain hydroxylase, using substrate misrecognition of P450s induced by decoy molecules. Furthermore, a number of H2O2-dependent bacterial P450s can catalyze the peroxygenation of a variety of nonnative substrates through a simple substrate-misrecognition trick, in which catalytic activities and enantioselectivity are dependent on the structure of decoy molecules.

  13. Posttranslational modification by an isolevuglandin diminishes activity of the mitochondrial cytochrome P450 27A1.

    Science.gov (United States)

    Charvet, Casey D; Laird, James; Xu, Yunfeng; Salomon, Robert G; Pikuleva, Irina A

    2013-05-01

    Posttranslational modification by isolevuglandins (isoLGs), arachidonate oxidation products, is an important yet understudied process associated with altered protein properties. This type of modification is detected in cytochrome P450 27A1 (CYP27A1), a multifunction enzyme expressed in almost every cell and involved in the metabolism of cholesterol and other sterols. Previously, the CYP27A1 Lys(358)-isoLG adduct was found in human retina afflicted with age-related macular degeneration. Yet, the effect of Lys(358) modification on enzyme activity was not investigated. Herein, we characterized catalytic properties of Lys(358) as well as Lys(476) CYP27A1 mutants before and after isoLG treatment and quantified the extent of modification by multiple reaction monitoring. The K358R mutant was less susceptible to isoLG-induced loss of catalytic activity than the wild type (WT), whereas the K476R mutant was nearly as vulnerable as the WT. Both mutants showed less isoLG modification than WT. Thus, modification of Lys(358), a residue involved in redox partner interactions, is the major contributor to isoLG-associated loss of CYP27A1 activity. Our data show the specificity of isoLG modification, provide direct evidence that isoLG adduction impairs enzyme activity, and support our hypothesis that isoLG modification in the retina is detrimental to CYP27A1 enzyme activity, potentially disrupting cholesterol homeostasis.

  14. Intracellular delivery of cytochrome c by galactosylated albumin to hepatocarcinoma cells.

    Science.gov (United States)

    Yeh, Tzyy-Harn; Wu, Fe-Lin Lin; Shen, Li-Jiuan

    2014-07-01

    In some cancer cells, translocation of cytochrome c (Cyt c) from mitochondria to the cytoplasma is inhibited. This inhibition prevents cells from undergoing apoptotic cell death and can lead to uncontrolled cell growth. Increasing cytoplasmic concentration of Cyt c can induce apoptosis in cancer cells as a strategy of cancer therapy. Here we proposed a galactosylated albumin based carrier for intracellular delivery of Cyt c to hepatocarcinoma cells. Galactosylated albumin is recognized by highly expressed asialoglycoprotein receptors (ASGPR) on hepatocarcinoma cells and is further internalized into cells via receptor mediated endocytosis. Cyt c was chemically conjugated to galactosylated albumin with a reducible disulfide linker in order to release Cyt c from the carrier inside cells. We tested cellular uptake and cytotoxicity of Cyt c conjugates in ASGPR positive and negative hepatocarcinoma cells. The results showed galatosylated albumin significantly increased cellular uptake in both cell types resulting in cytotoxicity in a dose dependent manner through the induction of apoptosis. The lack of ASGPR specific uptake might be due to other carbohydrate-recognizing receptors expressed on tumor cells. In general, our work has shown that intracellular delivery of Cyt c to tumor cells can be an alternative therapeutic approach and galactosylated albumin can be a protein drug carrier for intracellular delivery.

  15. Cytochrome P450-inhibitory activity of parabens and phthalates used in consumer products.

    Science.gov (United States)

    Ozaki, Hitomi; Sugihara, Kazumi; Watanabe, Yoko; Ohta, Shigeru; Kitamura, Shigeyuki

    2016-01-01

    The in vitro cytochrome P450 (CYP)-inhibitory effects of 11 parabens and 7 phthalates used in consumer products, as well as their hydrolytic metabolites, were investigated, using rat liver microsomes as an enzyme source. The effects on individual CYP isozymes were evaluated by assaying inhibition of activities towards specific substrates, i.e., ethoxyresorufin O-dealkylase (EROD), methoxyresorufin O-dealkylase (MROD), pentoxyresorufin O-dealkylase (PROD), 7-benzyloxy-4-trifluoromethylcoumarin dealkylase (BFCD), 7-methoxy-4-trifluoromethylcoumarin dealkylase (MFCD) and 7-ethoxy-4-trifluoromethylcoumarin dealkylase (EFCD) activities. These activities were dose-dependently inhibited, most potently by medium-side-chain parabens (C6-9) and phthalates (C4-6), and less potently by shorter- and longer-side-chain esters. The hydrolytic product of parabens, 4-hydroxybenzoic acid, was not inhibitory, while those of phthalates, phthalic acid monoesters, showed lower inhibitory activity than the parent phthalates. Parabens showed relatively potent inhibition of MFCD activity, considered to be mainly due to CYP2C, and phthalates showed relatively potent inhibition of PROD activity, considered to be mainly due to CYP2B.

  16. Molecular Dynamics Simulations of Cytochrome c un-folding in AOT Reverse Micelles: the first steps

    CERN Document Server

    Abel, Stéphane; Marchi, Massimo

    2009-01-01

    This paper explores the reduced form of horse cytochrome c confined in reverse micelles (RM) of so-dium bis-(2-ethylhexyl) sulfosuccinate (AOT) in isooctane by molecular dynamics simulation. RMs of two sizes were constructed at a water content of Wo = [H2O]/[AOT] = 5.5 and 9.1. Our results show that the protein secondary structure and the heme conformation both depend on micellar hydration. At low hydration, the protein structure and the heme moiety remain stable, whereas at high water content the protein becomes unstable and starts to unfold. At Wo = 9.1, according to the X-ray structure, conforma-tional changes are mainly localized on protein loops and around the heme moiety, where we observe a partial opening of the heme crevice. These findings suggest that within our time window (10 ns), the structural changes observed at the heme level are the first steps of the protein denaturation process, pre-viously described experimentally in micellar solutions. In addition, a specific binding of AOT molecules to a ...

  17. Pyrethroid activity-based probes for profiling cytochrome P450 activities associated with insecticide interactions.

    Science.gov (United States)

    Ismail, Hanafy M; O'Neill, Paul M; Hong, David W; Finn, Robert D; Henderson, Colin J; Wright, Aaron T; Cravatt, Benjamin F; Hemingway, Janet; Paine, Mark J I

    2013-12-03

    Pyrethroid insecticides are used to control diseases spread by arthropods. We have developed a suite of pyrethroid mimetic activity-based probes (PyABPs) to selectively label and identify P450s associated with pyrethroid metabolism. The probes were screened against pyrethroid-metabolizing and nonmetabolizing mosquito P450s, as well as rodent microsomes, to measure labeling specificity, plus cytochrome P450 oxidoreductase and b5 knockout mouse livers to validate P450 activation and establish the role for b5 in probe activation. Using PyABPs, we were able to profile active enzymes in rat liver microsomes and identify pyrethroid-metabolizing enzymes in the target tissue. These included P450s as well as related detoxification enzymes, notably UDP-glucuronosyltransferases, suggesting a network of associated pyrethroid-metabolizing enzymes, or "pyrethrome." Considering the central role P450s play in metabolizing insecticides, we anticipate that PyABPs will aid in the identification and profiling of P450s associated with insecticide pharmacology in a wide range of species, improving understanding of P450-insecticide interactions and aiding the development of unique tools for disease control.

  18. The effects of acute hydrogen sulfide poisoning on cytochrome P450 isoforms activity in rats.

    Science.gov (United States)

    Wang, Xianqin; Chen, Mengchun; Chen, Xinxin; Ma, Jianshe; Wen, Congcong; Pan, Jianchun; Hu, Lufeng; Lin, Guanyang

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe drugs, bupropion, metoprolol, midazolam, phenacetin, omeprazole, and tolbutamide, respectively. The experimental rats were randomly divided into two groups, control group and acute H2S poisoning group (inhaling 300 ppm for 2 h). The mixture of six probes was given to rats by oral administration and the blood samples were obtained at a series of time points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. The results for acute H2S poisoning and control groups were as follows: there was a statistically significant difference in the AUC and C max for bupropion, metoprolol, phenacetin, and tolbutamide, while there was no statistical pharmacokinetic difference for midazolam and omeprazole. Acute H2S poisoning could inhibit the activity of CYP2B6, CYP2D6, CYP1A2, and CYP2C9 in rats.

  19. The Effects of Acute Hydrogen Sulfide Poisoning on Cytochrome P450 Isoforms Activity in Rats

    Directory of Open Access Journals (Sweden)

    Xianqin Wang

    2014-01-01

    Full Text Available Hydrogen sulfide (H2S is the second leading cause of toxin related death (after carbon monoxide in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe drugs, bupropion, metoprolol, midazolam, phenacetin, omeprazole, and tolbutamide, respectively. The experimental rats were randomly divided into two groups, control group and acute H2S poisoning group (inhaling 300 ppm for 2 h. The mixture of six probes was given to rats by oral administration and the blood samples were obtained at a series of time points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. The results for acute H2S poisoning and control groups were as follows: there was a statistically significant difference in the AUC and Cmax for bupropion, metoprolol, phenacetin, and tolbutamide, while there was no statistical pharmacokinetic difference for midazolam and omeprazole. Acute H2S poisoning could inhibit the activity of CYP2B6, CYP2D6, CYP1A2, and CYP2C9 in rats.

  20. Improving the activity of cytochrome P450 BM-3 catalyzing indole hydroxylation by directed evolution.

    Science.gov (United States)

    Pengpai, Zhang; Sheng, Hu; Lehe, Mei; Yinlin, Lei; Zhihua, Jin; Guixiang, Hu

    2013-09-01

    Cytochrome P450 BM-3 (A74G/F87V/L188Q) could catalyze indole to produce indigo. To further improve this capability, random mutagenesis was performed on the heme domain of P450 BM-3 (A74G/F87V/L188Q) with error-prone PCR. A single mutant V445A was selected out from the error-prone library and exhibited the highest specific activity toward indole among the mutants obtained. The kinetic parameters of V445A were also highly improved. Compared with the parent enzyme, the turnover rate (k cat) of V445A was increased by 7.5 times, while its K m value decreased by 9.2 %. Consequently, the catalytic efficiency (k cat/K m) of V445A was raised to 8.2 times than that of the parent enzyme. Moreover, alanine was confirmed as the best amino acid substitution by saturated mutagenesis in Val445 position. Three-dimensional structure analysis was also used to rationalize the effect on the enzyme properties of the mutation. This study showed that random mutagenesis was efficient to identify mutants with potential values in industry and increased our insight into P450 BM-3.

  1. Cytochrome c oxidase I primers for corbiculate bees: DNA barcode and mini-barcode.

    Science.gov (United States)

    Françoso, E; Arias, M C

    2013-09-01

    Bees (Apidae), of which there are more than 19 900 species, are extremely important for ecosystem services and economic purposes, so taxon identity is a major concern. The goal of this study was to optimize the DNA barcode technique based on the Cytochrome c oxidase (COI) mitochondrial gene region. This approach has previously been shown to be useful in resolving taxonomic inconsistencies and for species identification when morphological data are poor. Specifically, we designed and tested new primers and standardized PCR conditions to amplify the barcode region for bees, focusing on the corbiculate Apids. In addition, primers were designed to amplify small COI amplicons and tested with pinned specimens. Short barcode sequences were easily obtained for some Bombus century-old museum specimens and shown to be useful as mini-barcodes. The new primers and PCR conditions established in this study proved to be successful for the amplification of the barcode region for all species tested, regardless of the conditions of tissue preservation. We saw no evidence of Wolbachia or numts amplification by these primers, and so we suggest that these new primers are of broad value for corbiculate bee identification through DNA barcode.

  2. Oxidative Modification of Cytochrome c by Tetrahydropapaveroline, an Isoquinoline-Derived Neurotoxin

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jung Hoon [Cheongju Univ., Cheongju (Korea, Republic of)

    2013-02-15

    Tetrahyropapaveroline (THP) is compound derived from dopamine metabolism and is capable of causing dopaminergic neurodegenerative disorder, such as Parkinson's disease (PD). The aim of this study was to evaluate the potential of THP to cause oxidative damage on the structure of cytochrome c (cyt c). Our data showed that THP led to protein aggregation and the formation of carbonyl compound in protein aggregates. THP also induced the release of iron from cyt c. Reactive oxygen species (ROS) scavengers and iron specific chelator inhibited the THP-mediated cyt c modification and carbonyl compound formation. The results of this study show that ROS may play a critical role in THP-induced cyt c modification and iron releasing of cyt c. When cyt c that has been exposed to THP was subsequently analyzed by amino acid analysis, lysine, histidine and methionine residues were particularly sensitive. It is suggested that oxidative damage of cyt c by THP might induce the increase of iron content in cells and subsequently led to the deleterious condition. This mechanism is associated with the deterioration of organs under neurodegenerative disorder such as PD.

  3. N-Terminal Pro-B-Type Natriuretic Peptide Plasma Levels as a Potential Biomarker for Cardiac Damage After Radiotherapy in Patients With Left-Sided Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    D' Errico, Maria P., E-mail: patderrico@libero.it [Department of Laboratory Medicine, ' A. Perrino' Hospital, Brindisi (Italy); Grimaldi, Luca [Department of Medical Physics, ' A. Perrino' Hospital, Brindisi (Italy); Petruzzelli, Maria F. [Department of Radiation Oncology, ' A. Perrino' Hospital, Brindisi (Italy); Gianicolo, Emilio A.L. [Clinical Physiology Institute, National Research Council (IFC-CNR), Pisa-Lecce (Italy); Tramacere, Francesco [Department of Radiation Oncology, ' A. Perrino' Hospital, Brindisi (Italy); Monetti, Antonio; Placella, Roberto [Department of Laboratory Medicine, ' A. Perrino' Hospital, Brindisi (Italy); Pili, Giorgio [Department of Medical Physics, ' A. Perrino' Hospital, Brindisi (Italy); Andreassi, Maria Grazia; Sicari, Rosa; Picano, Eugenio [Clinical Physiology Institute, National Research Council (IFC-CNR), Pisa-Lecce (Italy); Portaluri, Maurizio [Department of Radiation Oncology, ' A. Perrino' Hospital, Brindisi (Italy); Clinical Physiology Institute, National Research Council (IFC-CNR), Pisa-Lecce (Italy)

    2012-02-01

    Purpose: Adjuvant radiotherapy (RT) after breast-conserving surgery has been associated with increased cardiovascular mortality. Cardiac biomarkers may aid in identifying patients with radiation-mediated cardiac dysfunction. We evaluated the correlation between N-terminal pro-B-type natriuretic peptide (NT-proBNP) and troponin (TnI) and the dose of radiation to the heart in patients with left-sided breast cancer. Methods and Materials: NT-proBNP and TnI plasma concentrations were measured in 30 left-sided breast cancer patients (median age, 55.0 years) 5 to 22 months after RT (Group I) and in 30 left-sided breast cancer patients (median age, 57.0 years) before RT as control group (Group II). Dosimetric and geometric parameters of heart and left ventricle were determined in all patients of Group I. Seventeen patients underwent complete two-dimensional echocardiography. Results: NT-proBNP levels were significantly higher (p = 0.03) in Group I (median, 90.0 pg/ml; range, 16.7-333.1 pg/ml) than in Group II (median, 63.2 pg/ml; range, 11.0-172.5 pg/ml). TnI levels remained below the cutoff threshold of 0.07 ng/ml in both groups. In patients with NT-proBNP values above the upper limit of 125 pg/ml, there were significant correlations between plasma levels and V{sub 3Gy}(%) (p = 0.001), the ratios D{sub 15cm{sup 3}}(Gy)/D{sub mean}(Gy) (p = 0.01), the ratios D{sub 15cm}{sup 3}/D{sub 50%} (Gy) (p = 0.008) for the heart and correlations between plasma levels and V{sub 2Gy} (%) (p = 0.002), the ratios D{sub 1cm{sup 3}}(Gy)/D{sub mean}(Gy) (p = 0.03), and the ratios D{sub 0.5cm{sup 3}}(Gy)/D{sub 50%}(Gy) (p = 0.05) for the ventricle. Conclusions: Patients with left-sided breast cancer show higher values of NT-pro BNP after RT when compared with non-RT-treated matched patients, increasing in correlation with high doses in small volumes of heart and ventricle. The findings of this study show that the most important parameters are not the mean doses but instead the small

  4. Relationship between N-terminal pro-B type natriuretic peptide and extensive echocardiographic parameters in mild to moderate aortic stenosis

    Directory of Open Access Journals (Sweden)

    Cemri M

    2008-01-01

    Full Text Available Context: The N-terminal pro-B type natriuretic peptide levels (NT pro-BNP are increased in cases of volume or pressure overload. Aims: To examine NT pro-BNP levels and enclose whether any relationship is present between the levels of NT pro-BNP and extensive echocardiographic parameters in asymptomatic patients with mild to moderate aortic stenosis (AS. Settings and Design: A cross-sectional study about the NT pro-BNP levels was conducted in 37 asymptomatic AS patients and compared with 40 controls. Methods: Patients < 70 years old with mild to moderate AS with a peak transaortic gradient> 20 mm Hg in transthoracic echocardiogram were included in our study. Extensive echocardiographic parameters and NT pro-BNP levels were obtained from these patients and these indices were compared with the control population selected from the patients who had similar clinical characteristics with the AS patients. Statistical Analysis: NT-proBNP values were found to be distribution free. Spearman correlation coefficient was used for correlation analysis. Mean values were compared by the Kruskal-Wallis test. Results: The NT pro-BNP levels were increased in patients with AS (median; interquartiles range: 686 [449-855] pg/mL vs. 140 [116-150] pg/mL, P < 0.001. Among patients with AS, when correlation analysis was performed mean transaortic gradient, aortic valve area index, myocardial performance index, E m /A m ratio, left-ventricular mass index (LVMI and E/E m ratio had correlations (r=0.38, P = 0.026; r=-0.46, P =0.008; r=0.19, P =0,049; r=-0.22, P =0.04, r=0.49, P =0.003 and r=0.53, P < 0.001 respectively with plasma NT pro-BNP levels. The LVMI (r = 0.49, P = 0.003 and E/E m ratio (r = 0.53 P < 0.001 have the strongest correlations when compared to other parameters. Conclusion: Plasma NT pro-BNP levels are increased in even asymptomatic patients with AS and correlated with several echocardiographic parameters related to severity of AS and degree of diastolic

  5. Association of N-Terminal Pro-B-Type Natriuretic Peptide with Left Ventricular Structure and Function in Chronic Kidney Disease (From the Chronic Renal Insufficiency Cohort [CRIC])

    Science.gov (United States)

    Mishra, Rakesh K.; Li, Yongmei; Ricardo, Ana C.; Yang, Wei; Keane, Martin; Cuevas, Magdalena; Christenson, Robert; DeFilippi, Christopher; Chen, Jing; He, Jiang; Kallem, Radhakrishna R.; Raj, Dominic S.; Schelling, Jeffrey R.; Wright, Jackson; Go, Alan S.; Shlipak, Michael G.

    2017-01-01

    We evaluated the cross-sectional associations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) with cardiac structural and functional abnormalities in a cohort of chronic kidney disease (CKD) patients without clinical heart failure (HF), the Chronic Renal Insufficiency Cohort (n=3,232). Associations of NT-proBNP with echocardiographically determined left ventricular (LV) mass and LV systolic and diastolic function were evaluated by multivariable logistic and linear regression models. Reclassification of participants’ predicted risk of LV hypertrophy (LVH), systolic and diastolic dysfunction was performed using a category-free net reclassification improvement (NRI) index that compared a clinical model with and without NT-proBNP. The median (interquartile range) NT-proBNP was 126.6 pg/ml (55.5–303.7). The highest quartile of NT-proBNP was associated with nearly three-fold odds of LVH (odds ratio (OR) 2.7, 95% confidence interval (CI) 1.8–4.0) and LV systolic dysfunction (2.7, 1.7–4.5) and two-fold odds of diastolic dysfunction (2.0, 1.3–2.9) in the fully adjusted models. When evaluated alone as a screening test, NT-proBNP functioned modestly for the detection of LVH (area under the curve, AUC 0.66) and LV systolic dysfunction (AUC 0.62), and poorly for the detection of diastolic dysfunction (AUC 0.51). However, when added to the clinical model, NT-proBNP significantly reclassified participants’ likelihood of having LVH (NRI 0.14, 95% CI 0.13–0.15; p<0.001) and LV systolic dysfunction (0.28, 0.27–0.30; p<0.001), but not diastolic dysfunction (0.10, 0.10–0.11; p=0.07). In conclusion, in this large CKD cohort without HF, NT-proBNP had strong associations with prevalent LVH and LV systolic dysfunction. PMID:23178053

  6. Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI).

    Science.gov (United States)

    Reboul, Emmanuelle; Abou, Lydia; Mikail, Céline; Ghiringhelli, Odette; André, Marc; Portugal, Henri; Jourdheuil-Rahmani, Dominique; Amiot, Marie-Josèphe; Lairon, Denis; Borel, Patrick

    2005-04-15

    The carotenoid lutein is thought to play a role in the human eye and to protect against age-related macular degeneration. Lutein transport in the human intestine has not been characterized. We examined lutein transport processes using Caco-2 TC-7 monolayers as a model for human intestinal epithelium. Purified lutein was mixed with phospholipids, lysophospholipids, cholesterol, mono-olein, oleic acid and taurocholate to obtain lutein-rich mixed micelles that mimicked those found under physiological conditions. The micelles were added to the apical side of Caco-2 TC-7 cell monolayers for 30 min or 3 h at 37 degrees C. Absorbed lutein, i.e. the sum of lutein recovered in the scraped cells and in the basolateral chamber, was quantified by HPLC. Transport rate was measured (i) as a function of time (from 15 to 60 min), (ii) as a function of micellar lutein concentration (from 1.5 to 15 microM), (iii) at 4 degrees C, (iv) in the basolateral to apical direction, (v) after trypsin pretreatment, (vi) in the presence of beta-carotene and/or lycopene, (vii) in the presence of increasing concentrations of antibody against SR-BI (scavenger receptor class B type 1) and (viii) in the presence of increasing concentrations of a chemical inhibitor of the selective transfer of lipids mediated by SR-BI, i.e. BLT1 (blocks lipid transport 1). The rate of transport of lutein as a function of time and as a function of concentration was saturable. It was significantly lower at 4 degrees C than at 37 degrees C (approx. 50%), in the basal to apical direction than in the opposite direction (approx. 85%), and after trypsin pretreatment (up to 45%). Co-incubation with beta-carotene, but not lycopene, decreased the lutein absorption rate (approx. 20%) significantly. Anti-SR-BI antibody and BLT1 significantly impaired the absorption rate (approx. 30% and 57% respectively). Overall, these results indicate that lutein absorption is, at least partly, protein-mediated and that some lutein is taken up

  7. Cytochrome P450BM-3 (CYP102): regiospecificity of oxidation of omega-unsaturated fatty acids and mechanism-based inactivation.

    Science.gov (United States)

    Shirane, N; Sui, Z; Peterson, J A; Ortiz de Montellano, P R

    1993-12-14

    Cytochrome P450BM-3 preferentially oxidized fatty acids with terminal double or triple bonds to the omega-2 hydroxylated fatty acids rather than, respectively, to the epoxide or diacid metabolites. The enzyme is inactivated during catalytic turnover of long, terminally unsaturated fatty acids but not by the analogous medium-length fatty acids. Enzyme inactivation by 17-octadecynoic acid and 16-hydroxy-17-octadecynoic acid is due to alkylation of the prosthetic heme group to given an adduct tentatively identified as N-(2-oxo-3-hydroxy-17-carboxyheptadecyl)protoporphyrin IX by its chromatographic and spectroscopic properties. Catalytic turnover of 17-octadecenoic acid also results in heme modification. Fatty diacid monoethyl thioesters are introduced as a new class of irreversible inhibitors that exploit the omega-2 oxidation specificity of cytochrome P450BM-3. Catalytic oxidation of the monoethyl thioesters of dodecanedioic and hexadecanedioic acids results in enzyme inactivation and formation of the parent diacids as metabolites. Limited tryptic digestion of the enzyme after incubation with the monoethyl thioester of [14C]hexadecanedioic acid shows that the inactivating agent binds covalently to both the heme and flavin domains. This finding, and the observation that glutathione prevents inactivation of the enzyme by the monoethyl thioesters, indicate that a diffusible metabolite, probably the sulfoxide, is responsible for enzyme inactivation. The strong preference for omega-2 allylic or propargylic hydroxylation over terminal pi-bond oxidation is opposite to the usual cytochrome P450 pattern and requires that the enzyme actively suppress terminal pi-bond oxidation. The inference that the enzyme binds and sequesters the terminal carbon in a lipophilic pocket is consistent with the crystal structure of the hemoprotein domain of cytochrome P450BM-3.

  8. Analysis of cytochrome P450 metabolites of arachidonic acid by stable isotope probe labeling coupled with ultra high-performance liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Zhu, Quan-Fei; Hao, Yan-Hong; Liu, Ming-Zhou; Yue, Jiang; Ni, Jian; Yuan, Bi-Feng; Feng, Yu-Qi

    2015-09-04

    Cytochrome P450 metabolites of arachidonic acid (AA) belong to eicosanoids and are potent lipid mediators of inflammation. It is well-known that eicosanoids play an important role in numerous pathophysiological processes. Therefore, quantitative analysis of cytochrome P450 metabolites of AA, including hydroxyeicosatetraenoic acids (HETEs), epoxyeicosatreinoic acids (EETs), and dihydroxyeicosatrienoic acids (DHETs) can provide crucial information to uncover underlying mechanisms of cytochrome P450 metabolites of AA related diseases. Herein, we developed a highly sensitive method to identify and quantify HETEs, EETs, and DHETs in lipid extracts of biological samples based on stable isotope probe labeling coupled with ultra high-performance liquid chromatography/mass spectrometry. To this end, a pair of stable isotope probes, 2-dimethylaminoethylamine (DMED) and d4-2-dimethylaminoethylamine (d4-DMED), were utilized to facilely label eicosanoids. The heavy labeled eicosanoid standards were prepared and used as internal standards for quantification to minimize the matrix and ion suppression effects in mass spectrometry analysis. In addition, the detection sensitivities of DMED labeled eicosanoids improved by 3-104 folds in standard solution and 5-138 folds in serum matrix compared with unlabeled analytes. Moreover, a good separation of eicosanoids isomers was achieved upon DMED labeling. The established method provided substantial sensitivity (limit of quantification at sub-picogram), high specificity, and broad linear dynamics range (3 orders of magnitude). We further quantified cytochrome P450 metabolites of AA in rat liver, heart, brain tissues and human serum using the developed method. The results showed that 19 eicosanoids could be distinctly detected and the contents of 11-, 15-, 16-, 20-HETE, 5,6-EET, and 14,15-EET in type 2 diabetes mellitus patients and 5-, 11-, 12-, 15-, 16-, 20-HETE, 8,9-EET, and 5,6-DHET in myeloid leukemia patients had significant changes

  9. Force modulation and electrochemical gating of conductance in a cytochrome

    Science.gov (United States)

    Davis, Jason J.; Peters, Ben; Xi, Wang

    2008-09-01

    Scanning probe methods have been used to measure the effect of electrochemical potential and applied force on the tunnelling conductance of the redox metalloprotein yeast iso-1-cytochrome c (YCC) at a molecular level. The interaction of a proximal probe with any sample under test will, at this scale, be inherently perturbative. This is demonstrated with conductive probe atomic force microscopy (CP-AFM) current-voltage spectroscopy in which YCC, chemically adsorbed onto pristine Au(111) via its surface cysteine residue, is observed to become increasingly compressed as applied load is increased, with concomitant decrease in junction resistance. Electrical contact at minimal perturbation, where probe-molecule coupling is comparable to that in scanning tunnelling microscopy, brings with it the observation of negative differential resistance, assigned to redox-assisted probe-substrate tunnelling. The role of the redox centre in conductance is also resolved in electrochemical scanning tunnelling microscopy assays where molecular conductance is electrochemically gateable through more than an order of magnitude.

  10. Force modulation and electrochemical gating of conductance in a cytochrome

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Jason J; Peters, Ben; Xi Wang [Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA (United Kingdom)], E-mail: jason.davis@chem.ox.ac.uk

    2008-09-17

    Scanning probe methods have been used to measure the effect of electrochemical potential and applied force on the tunnelling conductance of the redox metalloprotein yeast iso-1-cytochrome c (YCC) at a molecular level. The interaction of a proximal probe with any sample under test will, at this scale, be inherently perturbative. This is demonstrated with conductive probe atomic force microscopy (CP-AFM) current-voltage spectroscopy in which YCC, chemically adsorbed onto pristine Au(111) via its surface cysteine residue, is observed to become increasingly compressed as applied load is increased, with concomitant decrease in junction resistance. Electrical contact at minimal perturbation, where probe-molecule coupling is comparable to that in scanning tunnelling microscopy, brings with it the observation of negative differential resistance, assigned to redox-assisted probe-substrate tunnelling. The role of the redox centre in conductance is also resolved in electrochemical scanning tunnelling microscopy assays where molecular conductance is electrochemically gateable through more than an order of magnitude.

  11. Upregulation of Mitochondrial Content in Cytochrome c Oxidase Deficient Fibroblasts.

    Science.gov (United States)

    Kogot-Levin, Aviram; Saada, Ann; Leibowitz, Gil; Soiferman, Devorah; Douiev, Liza; Raz, Itamar; Weksler-Zangen, Sarah

    2016-01-01

    Cytochrome-c-oxidase (COX) deficiency is a frequent cause of mitochondrial disease and is associated with a wide spectrum of clinical phenotypes. We studied mitochondrial function and biogenesis in fibroblasts derived from the Cohen (CDs) rat, an animal model of COX deficiency. COX activity in CDs-fibroblasts was 50% reduced compared to control rat fibroblasts (P<0.01). ROS-production in CDs fibroblasts increased, along with marked mitochondrial fragmentation and decreased mitochondrial membrane-potential, indicating mitochondrial dysfunction. Surprisingly, cellular ATP content, oxygen consumption rate (OCR) and the extracellular acidification rate (ECAR) were unchanged. To clarify the discrepancy between mitochondrial dysfunction and ATP production, we studied mitochondrial biogenesis and turnover. The content of mitochondria was higher in CDs-fibroblasts. Consistently, AMPK activity and the expression of NRF1-target genes, NRF2 and PGC1-α that mediate mitochondrial biogenesis were increased (P<0.01 vs control fibroblast). In CDs-fibrobalsts, the number of autophagosomes (LC3+ puncta) containing mitochondria in CDs fibroblasts was similar to that in control fibroblasts, suggesting that mitophagy was intact. Altogether, our findings demonstrate that mitochondrial dysfunction and oxidative stress are associated with an increase in mitochondrial biogenesis, resulting in preservation of ATP generation.

  12. Induction of diphenytriazol on cytochrome CYP1A

    Institute of Scientific and Technical Information of China (English)

    Yun-zhen HU; Tong-wei YAO

    2004-01-01

    AIM: To study the effects of diphenytriazol on cytochrome P-450 (CYP) enzymes. METHODS: SD rats were pretreated with diphenytriazol. The catalytic activities of rat liver microsomes were determined by assaying ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-dealkylase. Phenacetin and aminopyrine were selected as the substrate of CYP1A and CYP2B, respectively. The concentration of remaining substrate in microsomal incubates was determined by reversed-phase high-performance liquid chromatography (RP-HPLC). The inhibition of fluvoxamine or α-naphthoflavone on phenacetin metabolism was measured. RESULTS: Phenacetin was significantly metabolized in the diphenytriazol-treated microsomes and the metabolic degree increased according to the diphenytriazol-treatment days. There existed a significant correlation between the metabolic degree of phenacetin and EROD in the microsomes pretreated with diphenytriazol. Both fluvoxamine and α-naphthofiavone inhibited the metabolism of phenacetin significantly, and the inhibition constants (Ki) were (5.4± 1.0) μmol/L and (10.4±0.5)μmol/L, respectively. The activity of microsomes pretreated with diphenytriazol for 4 d was similar to that in β-naphthoflavone group, but was significantly different from those in control group and phenobarbital group.CONCLUSION: These results reveal that diphenytriazol is a novel inducer of CYP1A.

  13. Cytochrome c: A Multifunctional Protein Combining Conformational Rigidity with Flexibility

    Directory of Open Access Journals (Sweden)

    Reinhard Schweitzer-Stenner

    2014-01-01

    Full Text Available Cytochrome has served as a model system for studying redox reactions, protein folding, and more recently peroxidase activity induced by partial unfolding on membranes. This review illuminates some important aspects of the research on this biomolecule. The first part summarizes the results of structural analyses of its active site. Owing to heme-protein interactions the heme group is subject to both in-plane and out-of-plane deformations. The unfolding of the protein as discussed in detail in the second part of this review can be induced by changes of pH and temperature and most prominently by the addition of denaturing agents. Both the kinetic and thermodynamic folding and unfolding involve intermediate states with regard to all unfolding conditions. If allowed to sit at alkaline pH (11.5 for a week, the protein does not return to its folding state when the solvent is switched back to neutral pH. It rather adopts a misfolded state that is prone to aggregation via domain swapping. On the surface of cardiolipin containing liposomes, the protein can adopt a variety of partially unfolded states. Apparently, ferricytochrome c can perform biological functions even if it is only partially folded.

  14. The Membrane Modulates Internal Proton Transfer in Cytochrome c Oxidase

    DEFF Research Database (Denmark)

    Öjemyr, Linda Nasvik; Ballmoos, Christoph von; Faxén, Kristina;

    2012-01-01

    The functionality of membrane proteins is often modulated by the surrounding membrane. Here, we investigated the effect of membrane reconstitution of purified cytochrome c oxidase (CytcO) on the kinetics and thermodynamics of internal electron and proton-transfer reactions during O-2 reduction....... Reconstitution of the detergent-solubilized enzyme in small unilamellar soybean phosphatidylcholine vesicles resulted in a lowering of the pK(a) in the pH dependence profile of the proton-uptake rate. This pK(a) change resulted in decreased proton-uptake rates in the pH range of similar to 6.5-9.5, which...... is explained in terms of lowering of the pK(a) of an internal proton donor within CytcO. At pH 7.5, the rate decreased to the same extent when vesicles were prepared from the pure zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC),or the anionic lipid 1,2-dioleoyl-glycero-3-phospho (1-rac...

  15. Midkine Regulates BP through Cytochrome P450-Derived Eicosanoids.

    Science.gov (United States)

    Sato, Yuka; Sato, Waichi; Maruyama, Shoichi; Wilcox, Christopher S; Falck, John R; Masuda, Tomohiro; Kosugi, Tomoki; Kojima, Hiroshi; Maeda, Kayaho; Furuhashi, Kazuhiro; Ando, Masahiko; Imai, Enyu; Matsuo, Seiichi; Kadomatsu, Kenji

    2015-08-01

    The effects of endothelium-derived hyperpolarizing factors have been attributed to cytochrome P450-derived epoxyeicosatrienoic acids (EETs), but the regulation and role of EETs in endothelial dysfunction remain largely unexplored. Hypertension is a primary risk factor for renal dysfunction, which is frequently accompanied by various systemic diseases induced by endothelial dysfunction in the microcirculation. We previously reported that the endothelial growth factor midkine (MK) enhances hypertension in a model of CKD. Here, we investigated the hypothesis that MK regulates EET activity and thereby BP. MK gene-deleted mice were resistant to hypertension and developed less glomerulosclerosis and proteinuria after administration of a nitric oxide synthase (NOS) inhibitor in the setting of uninephrectomy. The hypertension observed in uninephrectomized wild-type mice after NOS inhibition was ameliorated by anti-MK antibody. MK-deficient mice produced higher amounts of EETs, and EETs dominantly regulated BP in these mice. Furthermore, MK administration to MK-deficient mice recapitulated the BP control observed in wild-type mice. EETs also dominantly regulated renal blood flow, which may influence renal function, in MK-deficient mice. Taken together, these results suggest that the MK/EET pathway is physiologically engaged in BP control and could be a target for the treatment of hypertension complicated by endothelial dysfunction.

  16. A spin label study of conformational changes in cytochrome c.

    Science.gov (United States)

    Postnikova, G B; Gorbunova, N P; Volkenstein, M V

    1983-04-01

    Spin-labeled pig heart cytochromes c singly modified at Met-65, Tyr-74 and at one of the lysine residues, Lys-72 or Lys-73, were investigated by the ESR method under conditions of different ligand and redox states of the heme and at various pH values. Replacement of Met-80 by the external ligand, cyanide, was shown to produce a sharp increase in the mobility of all the three bound labels while reduction of the spin-labeled ferricytochromes c did not cause any marked changes in their ESR spectra. In the pH range 6-13, two conformational transitions in ferricytochrome c were observed which preceded its alkaline denaturation: the first with pK 9.3 registered by the spin label at the Met-65 position, and the second with pK 11.1 registered by the labels bound to Tyr-74 and Lys-72(73). The conformational changes in the 'left-hand part' of ferricytochrome c are most probably induced in both cases by the exchange of internal protein ligands at the sixth coordination site of the heme.

  17. Cytochrome P450 genetic polymorphisms of Mexican indigenous populations.

    Science.gov (United States)

    Sosa-Macías, Martha; Llerena, Adrián

    2013-01-01

    This review focuses on the genetic polymorphisms of the cytochrome P450 (CYP) genes in Mexican indigenous populations, who are a part of the wide ethnic diversity of this country. These native groups have a particular historical trajectory that is different from the Mexican Mestizos. This variability may be reflected in the frequency distribution of polymorphisms in the CYP genes that encode enzymes involved in the metabolism of drugs and other xenobiotics. Therefore, these polymorphisms may affect drug efficacy and safety in indigenous populations in Mexico. The present study aimed to analyze the prevalence of CYP polymorphisms in indigenous Mexicans and to compare the results with studies in Mexican Mestizos. Because the extrapolation of pharmacogenetic data from Mestizos is not applicable to the majority of indigenous groups, pharmacogenetic studies directed at indigenous populations need to be developed. The Amerindians analyzed in this study showed a low phenotypic (CYP2D6) and genotypic (CYP2D6, CYP2C9) diversity, unlike Mexican Mestizos. The frequency of polymorphisms in the CYP1A1, CYP2C19, CYP2E1, and CYP3A4 genes was more similar among the Amerindians and Mexican Mestizos, with the exception of the CYP1A2 gene, whose *1F variant frequency in Mexican Amerindians was the highest described to date.

  18. Alternative Conformations of Cytochrome c: Structure, Function, and Detection.

    Science.gov (United States)

    Hannibal, Luciana; Tomasina, Florencia; Capdevila, Daiana A; Demicheli, Verónica; Tórtora, Verónica; Alvarez-Paggi, Damián; Jemmerson, Ronald; Murgida, Daniel H; Radi, Rafael

    2016-01-26

    Cytochrome c (cyt c) is a cationic hemoprotein of ∼100 amino acid residues that exhibits exceptional functional versatility. While its primary function is electron transfer in the respiratory chain, cyt c is also recognized as a key component of the intrinsic apoptotic pathway, the mitochondrial oxidative protein folding machinery, and presumably as a redox sensor in the cytosol, along with other reported functions. Transition to alternative conformations and gain-of-peroxidase activity are thought to further enable the multiple functions of cyt c and its translocation across cellular compartments. In vitro, direct interactions of cyt c with cardiolipin, post-translational modifications such as tyrosine nitration, phosphorylation, methionine sulfoxidation, mutations, and even fine changes in electrical fields lead to a variety of conformational states that may be of biological relevance. The identification of these alternative conformations and the elucidation of their functions in vivo continue to be a major challenge. Here, we unify the knowledge of the structural flexibility of cyt c that supports functional moonlighting and review biochemical and immunochemical evidence confirming that cyt c undergoes conformational changes during normal and altered cellular homeostasis.

  19. Glaucoma and Cytochrome P4501B1 Gene Mutations

    Directory of Open Access Journals (Sweden)

    Mukesh Tanwar

    2010-01-01

    Full Text Available Developmental anomalies of the ocular anterior chamber angle may lead to an incomplete development of the structures that form the conventional aqueous outflow pathway. Thus, disorders that present with such dysfunction tend to be associated with glaucoma. Among them, Axenfeld-Rieger (ARS malformation is a rare clinical entity with an estimated prevalence of one in every 200,000 individuals. The changes in eye morphogenesis in ARS are highly penetrant and are associated with 50% risk of development of glaucoma. Mutations in the cytochrome P4501B1 (CYP1B1 gene have been reported to be associated with primary congenital glaucoma and other forms of glaucoma and mutations in pituitary homeobox 2 (PITX2 gene have been identified in ARS in various studies. This case was negative for PITX2 mutations and compound heterozygote for CYP1B1 mutations. Clinical manifestations of this patient include bilateral elevated intraocular pressure (>40 mmHg with increased corneal diameter (>14 mm and corneal opacity. Patient also had iridocorneal adhesions, anteriorly displaced Schwalbe line, anterior insertion of iris, broad nasal bridge and protruding umbilicus. This is the first study from north India reporting CYP1B1 mutations in Axenfeld-Rieger syndrome with bilateral buphthalmos and early onset glaucoma. Result of this study supports the role of CYP1B1 as a causative gene in ASD disorders and its role in oculogenesis.

  20. High-throughput mass spectrometric cytochrome P450 inhibition screening.

    Science.gov (United States)

    Lim, Kheng B; Ozbal, Can C; Kassel, Daniel B

    2013-01-01

    We describe here a high-throughput assay to support rapid evaluation of drug discovery compounds for possible drug-drug interaction (DDI). Each compound is evaluated for its DDI potential by incubating over a range of eight concentrations and against a panel of six cytochrome P450 (CYP) enzymes: 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. The method utilizes automated liquid handling for sample preparation, and online solid-phase extraction/tandem mass spectrometry (SPE/MS/MS) for sample analyses. The system is capable of generating two 96-well assay plates in 30 min, and completes the data acquisition and analysis of both plates in about 30 min. Many laboratories that perform the CYP inhibition screening automate only part of the processes leaving a throughput bottleneck within the workflow. The protocols described in this chapter are aimed to streamline the entire process from assay to data acquisition and processing by incorporating automation and utilizing high-precision instrument to maximize throughput and minimize bottleneck.