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Sample records for human carbonyl reductase

  1. [High throughput screening of active and stereoselective carbonyl reductases].

    Science.gov (United States)

    Zhang, Hang; Chen, Xi; Feng, Jinhui; Bao, Jinku; Wu, Qiaqing; Zhu, Dunming

    2015-02-01

    In this study, a fast carbonyl reductases colorimetric screening method for discovering stereoselective carbonyl reductases was established by combining the reverse alcohol oxidation with the azoreductase-catalyzed reduction of azo dye. When azo dye (Orange I , 4-(4-hydroxy-1-naphthylazo) benzenesulfonic acid) and azoreductase (AzoB) were added into the reaction system of alcohol oxidation catalyzed by carbonyl reductase, the produced NAD(P)H served as electron donor for the azoreductase to reduce the azo dye, resulting the color fade. Hence, the carbonyl reductases can be screened by the obvious color change. When chiral alcohol was used as the substrate, the activity and stereoselectivity of carbonyl reductases can be screened at the same time.

  2. Human carbonyl reductase 1 participating in intestinal first-pass drug metabolism is inhibited by fatty acids and acyl-CoAs.

    Science.gov (United States)

    Hara, Akira; Endo, Satoshi; Matsunaga, Toshiyuki; El-Kabbani, Ossama; Miura, Takeshi; Nishinaka, Toru; Terada, Tomoyuki

    2017-08-15

    Human carbonyl reductase 1 (CBR1), a member of the short-chain dehydrogenase/reductase (SDR) superfamily, reduces a variety of carbonyl compounds including endogenous isatin, prostaglandin E2 and 4-oxo-2-nonenal. It is also a major non-cytochrome P450 enzyme in the phase I metabolism of carbonyl-containing drugs, and is highly expressed in the intestine. In this study, we found that long-chain fatty acids and their CoA ester derivatives inhibit CBR1. Among saturated fatty acids, myristic, palmitic and stearic acids were inhibitory, and stearic acid was the most potent (IC50 9µM). Unsaturated fatty acids (oleic, elaidic, γ-linolenic and docosahexaenoic acids) and acyl-CoAs (palmitoyl-, stearoyl- and oleoyl-CoAs) were more potent inhibitors (IC50 1.0-2.5µM), and showed high inhibitory selectivity to CBR1 over its isozyme CBR3 and other SDR superfamily enzymes (DCXR and DHRS4) with CBR activity. The inhibition by these fatty acids and acyl-CoAs was competitive with respect to the substrate, showing the Ki values of 0.49-1.2µM. Site-directed mutagenesis of the substrate-binding residues of CBR1 suggested that the interactions between the fatty acyl chain and the enzyme's Met141 and Trp229 are important for the inhibitory selectivity. We also examined CBR1 inhibition by oleic acid in cellular levels: The fatty acid effectively inhibited CBR1-mediated 4-oxo-2-nonenal metabolism in colon cancer DLD1 cells and increased sensitivity to doxorubicin in the drug-resistant gastric cancer MKN45 cells that highly express CBR1. The results suggest a possible new food-drug interaction through inhibition of CBR1-mediated intestinal first-pass drug metabolism by dietary fatty acids. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. The Drosophila carbonyl reductase sniffer is an efficient 4-oxonon-2-enal (4ONE) reductase.

    Science.gov (United States)

    Martin, Hans-Jörg; Ziemba, Marta; Kisiela, Michael; Botella, José A; Schneuwly, Stephan; Maser, Edmund

    2011-05-30

    Studies with the fruit-fly Drosophila melanogaster demonstrated that the enzyme sniffer prevented oxidative stress-induced neurodegeneration. Mutant flies overexpressing sniffer had significantly extended life spans in a 99.5% oxygen atmosphere compared to wild-type flies. However, the molecular mechanism of this protection remained unclear. Sequence analysis and database searches identified sniffer as a member of the short-chain dehydrogenase/reductase superfamily with a 27.4% identity to the human enzyme carbonyl reductase type I (CBR1). As CBR1 catalyzes the reduction of the lipid peroxidation products 4HNE and 4ONE, we tested whether sniffer is able to metabolize these lipid derived aldehydes by carbonyl reduction. To produce recombinant enzyme, the coding sequence of sniffer was amplified from a cDNA-library, cloned into a bacterial expression vector and the His-tagged protein was purified by Ni-chelate chromatography. We found that sniffer catalyzed the NADPH-dependent carbonyl reduction of 4ONE (K(m)=24±2 μM, k(cat)=500±10 min(-1), k(cat)/K(m)=350 s(-1) mM(-1)) but not that of 4HNE. The reaction product of 4ONE reduction by sniffer was mainly 4HNE as shown by HPLC- and GC/MS analysis. Since 4HNE, though still a potent electrophile, is less neurotoxic and protein reactive than 4ONE, one mechanism by which sniffer exerts its neuroprotective effects in Drosophila after oxidative stress may be enzymatic reduction of 4ONE. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  4. Specificity of human aldo-keto reductases, NAD(P)H:quinone oxidoreductase, and carbonyl reductases to redox-cycle polycyclic aromatic hydrocarbon diones and 4-hydroxyequilenin-o-quinone.

    Science.gov (United States)

    Shultz, Carol A; Quinn, Amy M; Park, Jong-Heum; Harvey, Ronald G; Bolton, Judy L; Maser, Edmund; Penning, Trevor M

    2011-12-19

    Polycyclic aromatic hydrocarbons (PAHs) are suspect human lung carcinogens and can be metabolically activated to remote quinones, for example, benzo[a]pyrene-1,6-dione (B[a]P-1,6-dione) and B[a]P-3,6-dione by the action of either P450 monooxygenase or peroxidases, and to non-K region o-quinones, for example B[a]P-7,8-dione, by the action of aldo keto reductases (AKRs). B[a]P-7,8-dione also structurally resembles 4-hydroxyequilenin o-quinone. These three classes of quinones can redox cycle, generate reactive oxygen species (ROS), and produce the mutagenic lesion 8-oxo-dGuo and may contribute to PAH- and estrogen-induced carcinogenesis. We compared the ability of a complete panel of human recombinant AKRs to catalyze the reduction of PAH o-quinones in the phenanthrene, chrysene, pyrene, and anthracene series. The specific activities for NADPH-dependent quinone reduction were often 100-1000 times greater than the ability of the same AKR isoform to oxidize the cognate PAH-trans-dihydrodiol. However, the AKR with the highest quinone reductase activity for a particular PAH o-quinone was not always identical to the AKR isoform with the highest dihydrodiol dehydrogenase activity for the respective PAH-trans-dihydrodiol. Discrete AKRs also catalyzed the reduction of B[a]P-1,6-dione, B[a]P-3,6-dione, and 4-hydroxyequilenin o-quinone. Concurrent measurements of oxygen consumption, superoxide anion, and hydrogen peroxide formation established that ROS were produced as a result of the redox cycling. When compared with human recombinant NAD(P)H:quinone oxidoreductase (NQO1) and carbonyl reductases (CBR1 and CBR3), NQO1 was a superior catalyst of these reactions followed by AKRs and last CBR1 and CBR3. In A549 cells, two-electron reduction of PAH o-quinones causes intracellular ROS formation. ROS formation was unaffected by the addition of dicumarol, suggesting that NQO1 is not responsible for the two-electron reduction observed and does not offer protection against ROS formation

  5. Chemoenzymatic synthesis of (S)-duloxetine using carbonyl reductase from Rhodosporidium toruloides.

    Science.gov (United States)

    Chen, Xiang; Liu, Zhi-Qiang; Lin, Chao-Ping; Zheng, Yu-Guo

    2016-04-01

    A chemoenzymatic strategy was developed for (S)-duloxetine production employing carbonyl reductases from newly isolated Rhodosporidium toruloides into the enantiodetermining step. Amongst the ten most permissive enzymes identified, cloned, and overexpressed in Escherichia coli, RtSCR9 exhibited excellent activity and enantioselectivity. Using co-expressed E. coli harboring both RtSCR9 and glucose dehydrogenase, (S)-3-(dimethylamino)-1-(2-thienyl)-1-propanol 3a was fabricated with so far the highest substrate loading (1000mM) in a space-time yield per gram of biomass (DCW) of 22.9mmolL(-1)h(-1)gDCW(-1) at a 200-g scale. The subsequent synthetic steps from RtSCR9-catalyzed (S)-3a were further performed, affording (S)-duloxetine with 60.2% overall yield from 2-acethylthiophene in >98.5% ee. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Comparative inhibition of tetrameric carbonyl reductase activity in pig heart cytosol by alkyl 4-pyridyl ketones.

    Science.gov (United States)

    Shimada, Hideaki; Tanigawa, Takahiro; Matayoshi, Kazunori; Katakura, Kazufumi; Babazono, Ken; Takayama, Hiroyuki; Murahashi, Tsuyoshi; Akita, Hiroyuki; Higuchi, Toshiyuki; Eto, Masashi; Imamura, Yorishige

    2014-06-01

    The present study is to elucidate the comparative inhibition of tetrameric carbonyl reductase (TCBR) activity by alkyl 4-pyridyl ketones, and to characterize its substrate-binding domain. The inhibitory effects of alkyl 4-pyridyl ketones on the stereoselective reduction of 4-benzoylpyridine (4-BP) catalyzed by TCBR were examined in the cytosolic fraction of pig heart. Of alkyl 4-pyridyl ketones, 4-hexanoylpyridine, which has a straight-chain alkyl group of five carbon atoms, inhibited most potently TCBR activity and was a competitive inhibitor. Furthermore, cyclohexyl pentyl ketone, which is substituted by cyclohexyl group instead of phenyl group of hexanophenone, had much lower ability to be reduced than hexanophenone. These results suggest that in addition to a hydrophobic cleft corresponding to a straight-chain alkyl group of five carbon atoms, a hydrophobic pocket with affinity for an aromatic group is located in the substrate-binding domain of TCBR.

  7. RNA-Seq approach for genetic improvement of meat quality in pig and evolutionary insight into the substrate specificity of animal carbonyl reductases.

    Science.gov (United States)

    Jung, Won Yong; Kwon, Seul Gi; Son, Minky; Cho, Eun Seok; Lee, Yuno; Kim, Jae Hwan; Kim, Byeong-Woo; Park, Da Hye; Hwang, Jung Hye; Kim, Tae Wan; Park, Hwa Choon; Park, Beom Young; Choi, Jong-Soon; Cho, Kwang Keun; Chung, Ki Hwa; Song, Young Min; Kim, Il Suk; Jin, Sang Keun; Kim, Doo Hwan; Lee, Seung-Won; Lee, Keun Woo; Bang, Woo Young; Kim, Chul Wook

    2012-01-01

    Changes in meat quality traits are strongly associated with alterations in postmortem metabolism which depend on genetic variations, especially nonsynonymous single nucleotide variations (nsSNVs) having critical effects on protein structure and function. To selectively identify metabolism-related nsSNVs, next-generation transcriptome sequencing (RNA-Seq) was carried out using RNAs from porcine liver, which contains a diverse range of metabolic enzymes. The multiplex SNV genotyping analysis showed that various metabolism-related genes had different nsSNV alleles. Moreover, many nsSNVs were significantly associated with multiple meat quality traits. Particularly, ch7:g.22112616A>G SNV was identified to create a single amino acid change (Thr/Ala) at the 145th residue of H1.3-like protein, very close to the putative 147th threonine phosphorylation site, suggesting that the nsSNV may affect multiple meat quality traits by affecting the epigenetic regulation of postmortem metabolism-related gene expression. Besides, one nonsynonymous variation, probably generated by gene duplication, led to a stop signal in porcine testicular carbonyl reductase (PTCR), resulting in a C-terminal (E281-A288) deletion. Molecular docking and energy minimization calculations indicated that the binding affinity of wild-type PTCR to 5α-DHT, a C(21)-steroid, was superior to that of C-terminal-deleted PTCR or human carbonyl reductase, which was very consistent with experimental data, reported previously. Furthermore, P284 was identified as an important residue mediating the specific interaction between PTCR and 5α-DHT, and phylogenetic analysis showed that P284 is an evolutionarily conserved residue among animal carbonyl reductases, which suggests that the C-terminal tails of these reductases may have evolved under evolutionary pressure to increase the substrate specificity for C(21)-steroids and facilitate metabolic adaptation. Altogether, our RNA-Seq revealed that selective nsSNVs were

  8. Improvement of operational stability of Ogataea minuta carbonyl reductase for chiral alcohol production.

    Science.gov (United States)

    Honda, Kohsuke; Inoue, Mizuha; Ono, Tomohiro; Okano, Kenji; Dekishima, Yasumasa; Kawabata, Hiroshi

    2017-06-01

    Directed evolution of enantio-selective carbonyl reductase from Ogataea minuta was conducted to improve the operational stability of the enzyme. A mutant library was constructed by an error-prone PCR and screened using a newly developed colorimetric assay. The stability of a mutant with two amino acid substitutions was significantly higher than that of the wild type at 50°C in the presence of dimethyl sulfoxide. Site-directed mutagenesis analysis showed that the improved stability of the enzyme can be attributed to the amino acid substitution of V166A. The half-lives of the V166A mutant were 11- and 6.1-times longer than those of the wild type at 50°C in the presence and absence, respectively, of 20% (v/v) dimethyl sulfoxide. No significant differences in the substrate specificity and enantio-selectivity of the enzyme were observed. The mutant enzyme converted 60 mM 2,2,2-trifluoroacetophenone to (R)-(-)-α-(trifluoromethyl)benzyl alcohol in a molar yield of 71% whereas the conversion yield with an equivalent concentration of the wild-type enzyme was 27%. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  9. Efficient synthesis of a (S)-fluoxetine intermediate using carbonyl reductase coupled with glucose dehydrogenase.

    Science.gov (United States)

    Tang, Yunping; Zhang, Guomei; Wang, Zheng; Liu, Dan; Zhang, Linglu; Zhou, Yafeng; Huang, Ju; Yu, Fangmiao; Yang, Zuisu; Ding, Guofang

    2017-11-01

    (S)-3-chloro-1-phenyl-1-propanol ((S)-CPPO) is an important chiral intermediate predominantly used in the synthesis of the chiral side chain of (S)-fluoxetine. In this study, carbonyl reductase (CBR) from Novosphingobium aromaticivorans was successfully expressed in recombinant E. coli. The enzymatic activity of the recombinant CBR was significantly increased to 1875 U/mL in the fed-batch fermentation in a 10 L fermenter and recombinant CBR was then purified and characterized. By regenerating NADH with glucose dehydrogenase, 100 g/L 3-chloro-1-phenyl-1-propanone (3-CPP) was successfully converted to (S)-CPPO with a conversion of 100% and ee value of 99.6% after 12 h at 30 °C in PBS buffer (pH 7.0), which are the highest reported to date for the bio-production of (S)-CPPO and presented great potential for green production of (S)-CPPO at industrial scale. Copyright © 2017. Published by Elsevier Ltd.

  10. The binding sites on human heme oxygenase-1 for cytochrome p450 reductase and biliverdin reductase.

    Science.gov (United States)

    Wang, Jinling; de Montellano, Paul R Ortiz

    2003-05-30

    Human heme oxygenase-1 (hHO-1) catalyzes the NADPH-cytochrome P450 reductase-dependent oxidation of heme to biliverdin, CO, and free iron. The biliverdin is subsequently reduced to bilirubin by biliverdin reductase. Earlier kinetic studies suggested that biliverdin reductase facilitates the release of biliverdin from hHO-1 (Liu, Y., and Ortiz de Montellano, P. R. (2000) J. Biol. Chem. 275, 5297-5307). We have investigated the binding of P450 reductase and biliverdin reductase to truncated, soluble hHO-1 by fluorescence resonance energy transfer and site-specific mutagenesis. P450 reductase and biliverdin reductase bind to truncated hHO-1 with Kd = 0.4 +/- 0.1 and 0.2 +/- 0.1 microm, respectively. FRET experiments indicate that biliverdin reductase and P450 reductase compete for binding to truncated hHO-1. Mutation of surface ionic residues shows that hHO-1 residues Lys18, Lys22, Lys179, Arg183, Arg198, Glu19, Glu127, and Glu190 contribute to the binding of cytochrome P450 reductase. The mutagenesis results and a computational analysis of the protein surfaces partially define the binding site for P450 reductase. An overlapping binding site including Lys18, Lys22, Lys179, Arg183, and Arg185 is similarly defined for biliverdin reductase. These results confirm the binding of biliverdin reductase to hHO-1 and define binding sites of the two reductases.

  11. Engineering of a novel carbonyl reductase with coenzyme regeneration in E. coli for efficient biosynthesis of enantiopure chiral alcohols.

    Science.gov (United States)

    Wei, Ping; Gao, Jia-Xin; Zheng, Gao-Wei; Wu, Hong; Zong, Min-Hua; Lou, Wen-Yong

    2016-07-20

    The novel anti-Prelog stereospecific carbonyl reductase from Acetobacter sp. CCTCC M209061 was successfully expressed in E. coli combined with glucose dehydrogenase (GDH) to construct an efficient whole-cell biocatalyst with coenzyme NADH regeneration. The enzymatic activity of GAcCR (AcCR with a GST tag) reached 304.9U/g-dcw, even 9 folds higher than that of wild strain, and the activity of GDH for NADH regeneration recorded 46.0U/mg-protein in the recombinant E. coli. As a whole-cell biocatalyst, the recombinant E. coli BL21(DE3)pLysS (pETDuet-gaccr-gdh) possessed a broad substrate spectrum for kinds of carbonyl compounds with encouraging yield and stereoselectivity. Besides, the asymmetric reduction of ethyl 4-chloroacetoacetate (COBE) to optically pure ethyl 4-chloro-3-hydroxybutyrate (CHBE) catalyzed by the whole-cell biocatalyst was systematically investigated. Under the optimal reaction conditions, the optical purity of CHBE was over 99% e.e. for (S)-enantiomer, and the initial rate and product yield reached 8.04μmol/min and 99.4%, respectively. Moreover, the space-time yield was almost 20 folds higher than that catalyzed by the wild strain. Therefore, a new, high efficiency biocatalyst for asymmetric reductions was constructed successfully, and the enantioselective reduction of prochiral compounds using the biocatalyst was a promising approach for obtaining enantiopure chiral alcohols. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Structure and characterization of a NAD(P)H-dependent carbonyl reductase from Pseudomonas aeruginosa PAO1.

    Science.gov (United States)

    Li, Shanshan; Teng, Xiaozhen; Su, Li; Mao, Guannan; Xu, Yueyang; Li, Tingting; Liu, Riuhua; Zhang, Qionglin; Wang, Yingying; Bartlam, Mark

    2017-06-01

    To investigate the function of the pa4079 gene from the opportunistic pathogen Pseudomonas aeruginosa PAO1, we determined its crystal structure and confirmed it to be a NAD(P)-dependent short-chain dehydrogenase/reductase. Structural similarity and activity for a broad range of substrates indicate that PA4079 functions as a carbonyl reductase. Comparison of apo- and holo-PA4079 shows that NADP stabilizes the active site specificity loop, and small molecule binding induces rotation of the Tyr183 side chain by approximately 90° out of the active site. Quantitative real-time PCR results show that pa4079 maintains high expression levels during antibiotic exposure. This work provides a starting point for understanding substrate recognition and selectivity by PA4079, as well as its possible reduction of antimicrobial drugs. Structural data are available in the Protein Data Bank (PDB) under the following accession numbers: apo PA4079 (condition I), 5WQM; apo PA4079 (condition II), 5WQN; PA4079 + NADP (condition I), 5WQO; PA4079 + NADP (condition II), 5WQP. © 2017 Federation of European Biochemical Societies.

  13. Efficicent (R-phenylethanol production with enantioselectivity-alerted (S-carbonyl reductase II and NADPH regeneration.

    Directory of Open Access Journals (Sweden)

    Rongzhen Zhang

    Full Text Available The NADPH-dependent (S-carbonyl reductaseII from Candida parapsilosis catalyzes acetophenone to chiral phenylethanol in a very low yield of 3.2%. Site-directed mutagenesis was used to design two mutants Ala220Asp and Glu228Ser, inside or adjacent to the substrate-binding pocket. Both mutations caused a significant enantioselectivity shift toward (R-phenylethanol in the reduction of acetophenone. The variant E228S produced (R-phenylethanol with an optical purity above 99%, in 80.2% yield. The E228S mutation resulted in a 4.6-fold decrease in the K M value, but nearly 5-fold and 21-fold increases in the k cat and k cat/K M values with respect to the wild type. For NADPH regeneration, Bacillus sp. YX-1 glucose dehydrogenase was introduced into the (R-phenylethanol pathway. A coexpression system containing E228S and glucose dehydrogenase was constructed. The system was optimized by altering the coding gene order on the plasmid and using the Shine-Dalgarno sequence and the aligned spacing sequence as a linker between them. The presence of glucose dehydrogenase increased the NADPH concentration slightly and decreased NADP(+ pool 2- to 4-fold; the NADPH/NADP(+ ratio was improved 2- to 5-fold. The recombinant Escherichia coli/pET-MS-SD-AS-G, with E228S located upstream and glucose dehydrogenase downstream, showed excellent performance, giving (R-phenylethanol of an optical purity of 99.5 % in 92.2% yield in 12 h in the absence of an external cofactor. When 0.06 mM NADP(+ was added at the beginning of the reaction, the reaction duration was reduced to 1 h. Optimization of the coexpression system stimulated an over 30-fold increase in the yield of (R-phenylethanol, and simultaneously reduced the reaction time 48-fold compared with the wild-type enzyme. This report describes possible mechanisms for alteration of the enantiopreferences of carbonyl reductases by site mutation, and cofactor rebalancing pathways for efficient chiral alcohols production.

  14. Biochemical properties of human dehydrogenase/reductase (SDR family) member 7.

    Science.gov (United States)

    Stambergova, Hana; Skarydova, Lucie; Dunford, James E; Wsol, Vladimir

    2014-01-25

    Dehydrogenase/reductase (SDR family) member 7 (DHRS7, retSDR4, SDR34C1) is a previously uncharacterized member of the short-chain dehydrogenase/reductase (SDR) superfamily. While human SDR members are known to play an important role in various (patho)biochemical pathways including intermediary metabolism and biotransformation of xenobiotics, only 20% of them are considered to be well characterized. Based on phylogenetic tree and SDR sequence clusters analysis DHRS7 is a close relative to well-known SDR member 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) that participates in metabolism of endogenous and xenobiotic substances with carbonyl group. The aim of present study is to determine the basic biochemical properties of DHRS7 and its possible involvement in metabolism of substrates with carbonyl group. For the first time the computational predictions of this membrane protein and membrane topology were experimentally confirmed. DHRS7 has been demonstrated to be an integral protein facing the lumen of the endoplasmic reticulum with lack of posttranscriptional glycosylation modification. Subsequently, NADP(H) cofactor preference and enzymatic reducing activity of DHRS7 was determined towards endogenous substrates with a steroid structure (cortisone, 4-androstene-3,17-dion) and also toward relevant exogenous substances bearing a carbonyl group harmful to human health (1,2-naphtoquinone, 9,10-phenantrenequinone). In addition to 11β-HSD1, DHRS7 is another enzyme from SDR superfamily that have been proved, at least in vitro, to contribute to the metabolism of xenobiotics with carbonyl group. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  15. A biotin enrichment strategy identifies novel carbonylated amino acids in proteins from human plasma

    DEFF Research Database (Denmark)

    Havelund, Jesper F.; Wojdyla, Katarzyna; Davies, Michael J.

    2017-01-01

    Protein carbonylation is an irreversible protein oxidation correlated with oxidative stress, various diseases and ageing. Here we describe a peptide-centric approach for identification and characterisation of up to 14 different types of carbonylated amino acids in proteins. The modified residues...... in vitro metal ion-catalysed oxidation. Furthermore, we assigned 133 carbonylated sites in 36 proteins in native human plasma protein samples. The optimised workflow enabled detection of 10 hitherto undetected types of carbonylated amino acids in proteins: aldehyde and ketone modifications of leucine...

  16. Directed Evolution of Carbonyl Reductase from Rhodosporidium toruloides and Its Application in Stereoselective Synthesis of tert-Butyl (3R,5S)-6-Chloro-3,5-dihydroxyhexanoate.

    Science.gov (United States)

    Liu, Zhi-Qiang; Wu, Lin; Zhang, Xiao-Jian; Xue, Ya-Ping; Zheng, Yu-Guo

    2017-05-10

    tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is a key intermediate of atorvastatin and rosuvastatin synthesis. Carbonyl reductase RtSCR9 from Rhodosporidium toruloides exhibited excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH). For the activity of RtSCR9 to be improved, random mutagenesis and site-saturation mutagenesis were performed. Three positive mutants were obtained (mut-Gln95Asp, mut-Ile144Lys, and mut-Phe156Gln). These mutants exhibited 1.94-, 3.03-, and 1.61-fold and 1.93-, 3.15-, and 1.97-fold improvement in the specific activity and kcat/Km, respectively. Asymmetric reduction of (S)-CHOH by mut-Ile144Lys coupled with glucose dehydrogenase was conducted. The yield and enantiomeric excess of (3R,5S)-CDHH reached 98 and 99%, respectively, after 8 h bioconversion in a single batch reaction with 1 M (S)-CHOH, and the space-time yield reached 542.83 mmol L-1 h-1 g-1 wet cell weight. This study presents a new carbonyl reductase for efficient synthesis of (3R,5S)-CDHH.

  17. Substrate channeling between the human dihydrofolate reductase and thymidylate synthase.

    Science.gov (United States)

    Wang, Nuo; McCammon, J Andrew

    2016-01-01

    In vivo, as an advanced catalytic strategy, transient non-covalently bound multi-enzyme complexes can be formed to facilitate the relay of substrates, i. e. substrate channeling, between sequential enzymatic reactions and to enhance the throughput of multi-step enzymatic pathways. The human thymidylate synthase and dihydrofolate reductase catalyze two consecutive reactions in the folate metabolism pathway, and experiments have shown that they are very likely to bind in the same multi-enzyme complex in vivo. While reports on the protozoa thymidylate synthase-dihydrofolate reductase bifunctional enzyme give substantial evidences of substrate channeling along a surface "electrostatic highway," attention has not been paid to whether the human thymidylate synthase and dihydrofolate reductase, if they are in contact with each other in the multi-enzyme complex, are capable of substrate channeling employing surface electrostatics. This work utilizes protein-protein docking, electrostatics calculations, and Brownian dynamics to explore the existence and mechanism of the substrate channeling between the human thymidylate synthase and dihydrofolate reductase. The results show that the bound human thymidylate synthase and dihydrofolate reductase are capable of substrate channeling and the formation of the surface "electrostatic highway." The substrate channeling efficiency between the two can be reasonably high and comparable to that of the protozoa. © 2015 The Protein Society.

  18. 5α-reductases in human physiology: an unfolding story.

    Science.gov (United States)

    Traish, Abdulmaged M

    2012-01-01

    5α-reductases are a family of isozymes expressed in a wide host of tissues including the central nervous system (CNS) and play a pivotal role in male sexual differentiation, development and physiology. A comprehensive literature search from 1970 to 2011 was made through PubMed and the relevant information was summarized. 5α reductases convert testosterone, progesterone, deoxycorticosterone, aldosterone and corticosterone into their respective 5α-dihydro-derivatives, which serve as substrates for 3α-hydroxysteroid dehydrogenase enzymes. The latter transforms these 5α-reduced metabolites into a subclass of neuroactive steroid hormones with distinct physiological functions. The neuroactive steroid hormones modulate a multitude of functions in human physiology encompassing regulation of sexual differentiation, neuroprotection, memory enhancement, anxiety, sleep and stress, among others. In addition, 5α -reductase type 3 is also implicated in the N-glycosylation of proteins via formation of dolichol phosphate. The family of 5α-reductases was targeted for drug development to treat pathophysiological conditions, such as benign prostatic hyperplasia and androgenetic alopecia. While the clinical use of 5α-reductase inhibitors was well established, the scope and the magnitude of the adverse side effects of such drugs, especially on the CNS, is still unrecognized due to lack of knowledge of the various physiological functions of this family of enzymes, especially in the CNS. There is an urgent need to better understand the function of 5α-reductases and the role of neuroactive steroids in human physiology in order to minimize the potential adverse side effects of inhibitors targeting 5α-reductases to treat benign prostatic hyperplasia and androgenic alopecia.

  19. Crystal structure of human quinone reductase type 2, a metalloflavoprotein.

    Science.gov (United States)

    Foster, C E; Bianchet, M A; Talalay, P; Zhao, Q; Amzel, L M

    1999-08-03

    In mammals, two separate but homologous cytosolic quinone reductases have been identified: NAD(P)H:quinone oxidoreductase type 1 (QR1) (EC 1.6.99.2) and quinone reductase type 2 (QR2). Although QR1 and QR2 are nearly 50% identical in protein sequence, they display markedly different catalytic properties and substrate specificities. We report here two crystal structures of QR2: in its native form and bound to menadione (vitamin K(3)), a physiological substrate. Phases were obtained by molecular replacement, using our previously determined rat QR1 structure as the search model. QR2 shares the overall fold of the major catalytic domain of QR1, but lacks the smaller C-terminal domain. The FAD binding sites of QR1 and QR2 are very similar, but their hydride donor binding sites are considerably different. Unexpectedly, we found that QR2 contains a specific metal binding site, which is not present in QR1. Two histidine nitrogens, one cysteine thiol, and a main chain carbonyl group are involved in metal coordination. The metal binding site is solvent-accessible, and is separated from the FAD cofactor by a distance of about 13 A.

  20. Proteome oxidative carbonylation during oxidative stress-induced premature senescence of WI-38 human fibroblasts

    DEFF Research Database (Denmark)

    Le Boulch, Marine; Ahmed, Emad K; Rogowska-Wrzesinska, Adelina

    2017-01-01

    Accumulation of oxidatively damaged proteins is a hallmark of cellular and organismal ageing, and is also a phenotypic feature shared by both replicative senescence and stress-induced premature senescence of human fibroblasts. Moreover, proteins that are building up as oxidized (i.e. the "Oxi......-proteome") during ageing and age-related diseases represent a restricted set of cellular proteins, indicating that certain proteins are more prone to oxidative carbonylation and subsequent intracellular accumulation. The occurrence of specific carbonylated proteins upon oxidative stress induced premature senescence...... to belong to functional interaction networks pointing to signalling pathways that have been implicated in the oxidative stress response and subsequent premature senescence....

  1. Biosynthesis of tert-butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate by carbonyl reductase from Rhodosporidium toruloides in mono and biphasic media.

    Science.gov (United States)

    Liu, Zhi-Qiang; Wu, Lin; Zheng, Ling; Wang, Wen-Zhong; Zhang, Xiao-Jian; Jin, Li-Qun; Zheng, Yu-Guo

    2017-10-05

    tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is the key intermediate for synthesis of atorvastatin and rosuvastatin. Carbonyl reductase exhibits excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) to synthesize (3R,5S)-CDHH. In this study, a whole cell biosynthesis reaction system to produce (3R,5S)-CDHH was constructed in organic solvents. A solution of 10% (v/v) Tween-80 was introduced to the reaction system as a co-solvent, which greatly enhanced biotransformation process, giving 98.9% yield, >99% ee and 1.8-fold higher space time yield in 5 h bioconversion of 1 M (S)-CHOH, compared with 98.7% yield and >99% ee in 9 h bioconversion of a purely aqueous reaction system. Moreover, a water-octanol biphasic reaction system was built and 20% of octanol was added as reservoir of substrate resulting in 98% yield, >99% ee and 4.08 mmol L-1 h-1 g-1 (wet cell weight) space time yield. This study paved a way for the whole cell biosynthesis of (3R,5S)-CDHH in mono and biphasic media. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Asymmetric reduction of ketopantolactone using a strictly (R)-stereoselective carbonyl reductase through efficient NADPH regeneration and the substrate constant-feeding strategy.

    Science.gov (United States)

    Zhao, Man; Gao, Liang; Zhang, Li; Bai, Yanbin; Chen, Liang; Yu, Meilan; Cheng, Feng; Sun, Jie; Wang, Zhao; Ying, Xiangxian

    2017-11-01

    To characterize a recombinant carbonyl reductase from Saccharomyces cerevisiae (SceCPR1) and explore its use in asymmetric synthesis of (R)-pantolactone [(R)-PL]. The NADPH-dependent SceCPR1 exhibited strict (R)-enantioselectivity and high activity in the asymmetric reduction of ketopantolactone (KPL) to (R)-PL. Escherichia coli, coexpressing SceCPR1 and glucose dehydrogenase from Exiguobacterium sibiricum (EsGDH), was constructed to fulfill efficient NADPH regeneration. During the whole-cell catalyzed asymmetric reduction of KPL, the spontaneous hydrolysis of KPL significantly affected the yield of (R)-PL, which was effectively alleviated by the employment of the substrate constant-feeding strategy. The established whole-cell bioreduction for 6 h afforded 458 mM (R)-PL with the enantiomeric excess value of >99.9% and the yield of 91.6%. Escherichia coli coexpressing SceCPR1 and EsGDH efficiently catalyzed the asymmetric synthesis of (R)-PL through the substrate constant-feeding strategy.

  3. Kinetics of reversible reductive carbonylation of heme in human cystathionine β-synthase.

    Science.gov (United States)

    Carballal, Sebastián; Cuevasanta, Ernesto; Marmisolle, Inés; Kabil, Omer; Gherasim, Carmen; Ballou, David P; Banerjee, Ruma; Alvarez, Beatriz

    2013-07-02

    Cystathionine β-synthase (CBS) catalyzes the condensation of homocysteine with serine or cysteine to form cystathionine and water or hydrogen sulfide (H2S), respectively. In addition to pyridoxal phosphate, human CBS has a heme cofactor with cysteine and histidine as ligands. While Fe(III)-CBS is inert to exogenous ligands, Fe(II)-CBS can be reversibly inhibited by carbon monoxide (CO) and reoxidized by O2 to yield superoxide radical. In this study, we have examined the kinetics of Fe(II)CO-CBS formation and reoxidation. Reduction of Fe(III)-CBS by dithionite showed a square root dependence on concentration, indicating that the reductant species was the sulfur dioxide radical anion (SO2(•-)) that exists in rapid equilibrium with S2O4(2-). Formation of Fe(II)CO-CBS from Fe(II)-CBS and 1 mM CO occurred with a rate constant of (3.1 ± 0.4) × 10(-3) s(-1) (pH 7.4, 25 °C). The reaction of Fe(III)-CBS with the reduced form of the flavoprotein methionine synthase reductase in the presence of CO and NADPH resulted in its reduction and carbonylation to form Fe(II)CO-CBS. Fe(II)-CBS was formed as an intermediate with a rate constant of (9.3 ± 2.5) × 10(2) M(-1) s(-1). Reoxidation of Fe(II)CO-CBS by O2 was multiphasic. The major phase showed a hyperbolic dependence on O2 concentration. Although H2S is a product of the CBS reaction and a potential heme ligand, we did not find evidence of an effect of exogenous H2S on activity or heme binding. Reversible reduction of CBS by a physiologically relevant oxidoreductase is consistent with a regulatory role for the heme and could constitute a mechanism for cross talk among the CO, H2S, and superoxide signaling pathways.

  4. Human microsomal carbonyl reducing enzymes in the metabolism of xenobiotics: well-known and promising members of the SDR superfamily.

    Science.gov (United States)

    Skarydová, Lucie; Wsól, Vladimír

    2012-05-01

    The best known, most widely studied enzyme system in phase I biotransformation is cytochrome P450 (CYP), which participates in the metabolism of roughly 9 of 10 drugs in use today. The main biotransformation isoforms of CYP are associated with the membrane of the endoplasmatic reticulum (ER). Other enzymes that are also active in phase I biotransformation are carbonyl reducing enzymes. Much is known about the role of cytosolic forms of carbonyl reducing enzymes in the metabolism of xenobiotics, but their microsomal forms have been mostly poorly studied. The only well-known microsomal carbonyl reducing enzyme taking part in the biotransformation of xenobiotics is 11β-hydroxysteroid dehydrogenase 1, a member of the short-chain dehydrogenase/reductase superfamily. Physiological roles of microsomal carbonyl reducing enzymes are better known than their participation in the metabolism of xenobiotics. This review is a summary of the fragmentary information known about the roles of the microsomal forms. Besides 11β-hydroxysteroid dehydrogenase 1, it has been reported, so far, that retinol dehydrogenase 12 participates only in the detoxification of unsaturated aldehydes formed upon oxidative stress. Another promising group of microsomal biotransformation carbonyl reducing enzymes are some members of 17β-hydroxysteroid dehydrogenases. Generally, it is clear that this area is, overall, quite unexplored, but carbonyl reducing enzymes located in the ER have proven very interesting. The study of these enzymes could shed new light on the metabolism of several clinically used drugs or they could become an important target in connection with some diseases.

  5. Substrate Specificity, Inhibitor Selectivity and Structure-Function Relationships of Aldo-Keto Reductase 1B15: A Novel Human Retinaldehyde Reductase.

    Directory of Open Access Journals (Sweden)

    Joan Giménez-Dejoz

    Full Text Available Human aldo-keto reductase 1B15 (AKR1B15 is a newly discovered enzyme which shares 92% amino acid sequence identity with AKR1B10. While AKR1B10 is a well characterized enzyme with high retinaldehyde reductase activity, involved in the development of several cancer types, the enzymatic activity and physiological role of AKR1B15 are still poorly known. Here, the purified recombinant enzyme has been subjected to substrate specificity characterization, kinetic analysis and inhibitor screening, combined with structural modeling. AKR1B15 is active towards a variety of carbonyl substrates, including retinoids, with lower kcat and Km values than AKR1B10. In contrast to AKR1B10, which strongly prefers all-trans-retinaldehyde, AKR1B15 exhibits superior catalytic efficiency with 9-cis-retinaldehyde, the best substrate found for this enzyme. With ketone and dicarbonyl substrates, AKR1B15 also shows higher catalytic activity than AKR1B10. Several typical AKR inhibitors do not significantly affect AKR1B15 activity. Amino acid substitutions clustered in loops A and C result in a smaller, more hydrophobic and more rigid active site in AKR1B15 compared with the AKR1B10 pocket, consistent with distinct substrate specificity and narrower inhibitor selectivity for AKR1B15.

  6. Catalytic properties and crystal structure of thermostable NAD(P)H-dependent carbonyl reductase from the hyperthermophilic archaeon Aeropyrum pernix K1.

    Science.gov (United States)

    Fukuda, Yudai; Sakuraba, Haruhiko; Araki, Tomohiro; Ohshima, Toshihisa; Yoneda, Kazunari

    2016-09-01

    A gene encoding NAD(P)H-dependent carbonyl reductase (CR) from the hyperthermophilic archaeon Aeropyrum pernix K1 was overexpressed in Escherichia coli. Its product was effectively purified and characterized. The expressed enzyme was the most thermostable CR found to date; the activity remained at approximately 75% of its activity after incubation for 10min up to 90°C. In addition, A. pernix CR exhibited high stability at a wider range of pH values and longer periods of storage compared with CRs previously identified from other sources. A. pernix CR catalyzed the reduction of various carbonyl compounds including ethyl 4-chloro-3-oxobutanoate and 9,10-phenanthrenequinone, similar to the CR from thyroidectomized (Tx) chicken fatty liver. However, A. pernix CR exhibited significantly higher Km values against several substrates than Tx chicken fatty liver CR. The three-dimensional structure of A. pernix CR was determined using the molecular replacement method at a resolution of 2.09Å, in the presence of NADPH. The overall fold of A. pernix CR showed moderate similarity to that of Tx chicken fatty liver CR; however, A. pernix CR had no active-site lid unlike Tx chicken fatty liver CR. Consequently, the active-site cavity in the A. pernix CR was much more solvent-accessible than that in Tx chicken fatty liver CR. This structural feature may be responsible for the enzyme's lower affinity for several substrates and NADPH. The factors contributing to the much higher thermostability of A. pernix CR were analyzed by comparing its structure with that of Tx chicken fatty liver CR. This comparison showed that extensive formation of the intrasubunit ion pair networks, and the presence of the strong intersubunit interaction, is likely responsible for A. pernix CR thermostability. Site-directed mutagenesis showed that Glu99 plays a major role in the intersubunit interaction. This is the first report regarding the characteristics and three-dimensional structure of

  7. Highly efficient bioreduction of 2-hydroxyacetophenone to (S)- and (R)-1-phenyl-1,2-ethanediol by two substrate tolerance carbonyl reductases with cofactor regeneration.

    Science.gov (United States)

    Cui, Zhi-Mei; Zhang, Jian-Dong; Fan, Xiao-Jun; Zheng, Gao-Wei; Chang, Hong-Hong; Wei, Wen-Long

    2017-02-10

    Optically pure 1-phenyl-1,2-ethanediol is a very important chiral building block and intermediate in fine chemical and pharmaceutical industries. Reduction of 2-hydroxyacetophenone provides a straightforward approach to access these important compounds. In this study, two enantiocomplementary carbonyl reductases, BDHA (2,3-butanediol dehydrogenase from Bacillus subtilis) and GoSCR (polyol dehydrogenase from Gluconobacter oxydans) were discovered for the first time to convert 2-hydroxyacetophenone (2-HAP) to (R)-1-phenyl-1,2-ethanediol ((R)-PED) and (S)-1-phenyl-1,2-ethanediol ((S)-PED) with excellent stereochemical selectivity, respectively. The two enzymes were purified and characterized. In vitro bioreduction of 2-HAP catalyzed by BDHA and GoSCR coupled with glucose dehydrogenase (GDH) from Bacillus subtilis for cofactor regeneration were demonstrated, affording both (R)-PED and (S)-PED in>99% ee and 99% conversion. Recombinant Escherichia coli whole cells co-expressing both GDH and BDHA or GoSCR genes were used to asymmetric reduction of 2-HAP to (R)-PED or (S)-PED. Under the optimized conditions, the bioreduction of 400mM (54g/L) substrate was proceeded smoothly without the external addition of cofactor, and the product (R)-PED and (S)-PED were obtained with 99% yield, >99% ee and 18.0g/L/h volumetric productivity. These results offer a practical biocatalytic method for the preparation of both (R)-PED and (S)-PED with high volumetric productivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Anthracycline-Related Cardiomyopathy After Childhood Cancer: Role of Polymorphisms in Carbonyl Reductase Genes—A Report From the Children's Oncology Group

    Science.gov (United States)

    Blanco, Javier G.; Sun, Can-Lan; Landier, Wendy; Chen, Lu; Esparza-Duran, Diego; Leisenring, Wendy; Mays, Allison; Friedman, Debra L.; Ginsberg, Jill P.; Hudson, Melissa M.; Neglia, Joseph P.; Oeffinger, Kevin C.; Ritchey, A. Kim; Villaluna, Doojduen; Relling, Mary V.; Bhatia, Smita

    2012-01-01

    Purpose Carbonyl reductases (CBRs) catalyze reduction of anthracyclines to cardiotoxic alcohol metabolites. Polymorphisms in CBR1 and CBR3 influence synthesis of these metabolites. We examined whether single nucleotide polymorphisms in CBR1 (CBR1 1096G>A) and/or CBR3 (CBR3 V244M) modified the dose-dependent risk of anthracycline-related cardiomyopathy in childhood cancer survivors. Patients and Methods One hundred seventy survivors with cardiomyopathy (patient cases) were compared with 317 survivors with no cardiomyopathy (controls; matched on cancer diagnosis, year of diagnosis, length of follow-up, and race/ethnicity) using conditional logistic regression techniques. Results A dose-dependent association was observed between cumulative anthracycline exposure and cardiomyopathy risk (0 mg/m2: reference; 1 to 100 mg/m2: odds ratio [OR], 1.65; 101 to 150 mg/m2: OR, 3.85; 151 to 200 mg/m2: OR, 3.69; 201 to 250 mg/m2: OR, 7.23; 251 to 300 mg/m2: OR, 23.47; > 300 mg/m2: OR, 27.59; Ptrend cardiomyopathy. Among individuals with CBR3 V244M homozygous G genotypes (CBR3:GG), exposure to low- to moderate-dose anthracyclines increased cardiomyopathy risk when compared with individuals with CBR3:GA/AA genotypes unexposed to anthracyclines (OR, 5.48; P = .003), as well as exposed to low- to moderate-dose anthracyclines (OR, 3.30; P = .006). High-dose anthracyclines (> 250 mg/m2) were associated with increased cardiomyopathy risk, irrespective of CBR genotype status. Conclusion This study demonstrates increased anthracycline-related cardiomyopathy risk at doses as low as 101 to 150 mg/m2. Homozygosis for G allele in CBR3 contributes to increased cardiomyopathy risk associated with low- to moderate-dose anthracyclines, such that there seems to be no safe dose for patients homozygous for the CBR3 V244M G allele. These results suggest a need for targeted intervention for those at increased risk of cardiomyopathy. PMID:22124095

  9. Binding of Natural and Synthetic Polyphenols to Human Dihydrofolate Reductase

    Directory of Open Access Journals (Sweden)

    José Neptuno Rodríguez-López

    2009-12-01

    Full Text Available Dihydrofolate reductase (DHFR is the subject of intensive investigation since it appears to be the primary target enzyme for antifolate drugs. Fluorescence quenching experiments show that the ester bond-containing tea polyphenols (--epigallocatechin gallate (EGCG and (--epicatechin gallate (ECG are potent inhibitors of DHFR with dissociation constants (KD of 0.9 and 1.8 μM, respectively, while polyphenols lacking the ester bound gallate moiety [e.g., (--epigallocatechin (EGC and (--epicatechin (EC] did not bind to this enzyme. To avoid stability and bioavailability problems associated with tea catechins we synthesized a methylated derivative of ECG (3-O-(3,4,5-trimethoxybenzoyl-(--epicatechin; TMECG, which effectively binds to DHFR (KD = 2.1 μM. In alkaline solution, TMECG generates a stable quinone methide product that strongly binds to the enzyme with a KD of 8.2 nM. Quercetin glucuronides also bind to DHFR but its effective binding was highly dependent of the sugar residue, with quercetin-3-xyloside being the stronger inhibitor of the enzyme with a KD of 0.6 μM. The finding that natural polyphenols are good inhibitors of human DHFR could explain the epidemiological data on their prophylactic effects for certain forms of cancer and open a possibility for the use of natural and synthetic polyphenols in cancer chemotherapy.

  10. Large-scale synthesis of tert-butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate by a stereoselective carbonyl reductase with high substrate concentration and product yield.

    Science.gov (United States)

    Liu, Zhi-Qiang; Hu, Zhong-Liang; Zhang, Xiao-Jian; Tang, Xiao-Ling; Cheng, Feng; Xue, Ya-Ping; Wang, Ya-Jun; Wu, Lin; Yao, Dan-Kai; Zhou, Yi-Teng; Zheng, Yu-Guo

    2017-05-01

    To biosynthesize the (3R,5S)-CDHH in an industrial scale, a newly synthesized stereoselective short chain carbonyl reductase (SCR) was successfully cloned and expressed in Escherichia coli. The fermentation of recombinant E. coli harboring SCR was carried out in 500 L and 5000 L fermenters, with biomass and specific activity of 9.7 g DCW/L, 15749.95 U/g DCW, and 10.97 g DCW/L, 19210.12 U/g DCW, respectively. The recombinant SCR was successfully applied for efficient production of (3R,5S)-CDHH. The scale-up synthesis of (3R,5S)-CDHH was performed in 5000 L bioreactor with 400 g/L of (S)-CHOH at 30°C, resulting in a space-time yield of 13.7 mM/h/g DCW, which was the highest ever reported. After isolation and purification, the yield and d.e. of (3R,5S)-CDHH reached 97.5% and 99.5%, respectively. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:612-620, 2017. © 2017 American Institute of Chemical Engineers.

  11. The stability of the three transmembrane and the four transmembrane human vitamin K epoxide reductase models

    Science.gov (United States)

    Wu, Sangwook

    2016-04-01

    The three transmembrane and the four transmembrane helix models are suggested for human vitamin K epoxide reductase (VKOR). In this study, we investigate the stability of the human three transmembrane/four transmembrane VKOR models by employing a coarse-grained normal mode analysis and molecular dynamics simulation. Based on the analysis of the mobility of each transmembrane domain, we suggest that the three transmembrane human VKOR model is more stable than the four transmembrane human VKOR model.

  12. Subcellular localization of the five members of the human steroid 5α-reductase family

    Directory of Open Access Journals (Sweden)

    Antonella Scaglione

    2017-06-01

    We report the cloning and transient expression in HeLa cells of the five members of the human steroid 5α-reductase family as both N- and C-terminus green fluorescent protein tagged protein constructs. Following the intrinsic fluorescence of the tag, we have determined that the subcellular localization of these enzymes is in the endoplasmic reticulum, upon expression in HeLa cells. The presence of the tag at either end of the polypeptide chain can affect protein expression and, in the case of trans enoyl-CoA reductase, it induces the formation of protein aggregates.

  13. Molecular cloning and expression of the human Δ7-sterol reductase

    Science.gov (United States)

    Moebius, Fabian F.; Fitzky, Barbara U.; Lee, Joon No; Paik, Young-Ki; Glossmann, Hartmut

    1998-01-01

    Inhibitors of the last steps of cholesterol biosynthesis such as AY9944 and BM15766 severely impair brain development. Their molecular target is the Δ7-sterol reductase (EC 1.3.1.21), suspected to be defective in the Smith–Lemli–Opitz syndrome, a frequent inborn disorder of sterol metabolism. Molecular cloning of the cDNA revealed that the human enzyme is a membrane-bound protein with a predicted molecular mass of 55 kDa and six to nine putative transmembrane segments. The protein is structurally related to plant and yeast sterol reductases. In adults the ubiquitously transcribed mRNA is most abundant in adrenal gland, liver, testis, and brain. The Δ7-sterol reductase is the ultimate enzyme of cholesterol biosynthesis in vertebrates and is absent from yeast. Microsomes from Saccharomyces cerevisiae strains heterologously expressing the human cDNA remove the C7–8 double bond in 7-dehydrocholesterol. The conversion to cholesterol depends on NADPH and is potently inhibited by AY9944 (IC50 0.013 μM), BM15766 (IC50 1.2 μM), and triparanol (IC50 14 μM). Our work paves the way to clarify whether a defect in the Δ7-sterol reductase gene underlies the Smith–Lemli–Opitz syndrome. PMID:9465114

  14. Role of aldo-keto reductase family 1 (AKR1) enzymes in human steroid metabolism.

    Science.gov (United States)

    Rižner, Tea Lanišnik; Penning, Trevor M

    2014-01-01

    Human aldo-keto reductases AKR1C1-AKR1C4 and AKR1D1 play essential roles in the metabolism of all steroid hormones, the biosynthesis of neurosteroids and bile acids, the metabolism of conjugated steroids, and synthetic therapeutic steroids. These enzymes catalyze NADPH dependent reductions at the C3, C5, C17 and C20 positions on the steroid nucleus and side-chain. AKR1C1-AKR1C4 act as 3-keto, 17-keto and 20-ketosteroid reductases to varying extents, while AKR1D1 acts as the sole Δ(4)-3-ketosteroid-5β-reductase (steroid 5β-reductase) in humans. AKR1 enzymes control the concentrations of active ligands for nuclear receptors and control their ligand occupancy and trans-activation, they also regulate the amount of neurosteroids that can modulate the activity of GABAA and NMDA receptors. As such they are involved in the pre-receptor regulation of nuclear and membrane bound receptors. Altered expression of individual AKR1C genes is related to development of prostate, breast, and endometrial cancer. Mutations in AKR1C1 and AKR1C4 are responsible for sexual development dysgenesis and mutations in AKR1D1 are causative in bile-acid deficiency. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. A DFT-based QSAR study on inhibition of human dihydrofolate reductase.

    Science.gov (United States)

    Karabulut, Sedat; Sizochenko, Natalia; Orhan, Adnan; Leszczynski, Jerzy

    2016-11-01

    Diaminopyrimidine derivatives are frequently used as inhibitors of human dihydrofolate reductase, for example in treatment of patients whose immune system are affected by human immunodeficiency virus. Forty-seven dicyclic and tricyclic potential inhibitors of human dihydrofolate reductase were analyzed using the quantitative structure-activity analysis supported by DFT-based and DRAGON-based descriptors. The developed model yielded an RMSE deviation of 1.1 a correlation coefficient of 0.81. The prediction set was characterized by R 2 =0.60 and RMSE=3.59. Factors responsible for inhibition process were identified and discussed. The resulting model was validated via cross validation and Y-scrambling procedure. From the best model, we found several mass-related descriptors and Sanderson electronegativity-related descriptors that have the best correlations with the investigated inhibitory concentration. These descriptors reflect results from QSAR studies based on characteristics of human dihydrofolate reductase inhibitors. Copyright © 2016. Published by Elsevier Inc.

  16. Aluminium, carbonyls and cytokines in human nipple aspirate fluids: Possible relationship between inflammation, oxidative stress and breast cancer microenvironment.

    Science.gov (United States)

    Mannello, F; Ligi, D; Canale, M

    2013-11-01

    The human breast is likely exposed to Al (aluminium) from many sources including diet and personal care products. Underarm applications of aluminium salt-based antiperspirant provide a possible long-term source of exposure, especially after underarm applications to shaved and abraded skin. Al research in breast fluids likely reflects the intraductal microenvironment. We found increased levels of aluminium in noninvasively collected nipple aspirate fluids (NAF) from 19 breast cancer patients compared with 16 healthy control subjects (268 vs 131 μg/l, respectively; p Aluminium content and carbonyl levels showed a significant positive linear correlation (r(2) 0.6628, p aluminium salts) we also found a significantly increased levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-12 p70, and TNF-α) and chemoattractant CC and CXC chemokines (IL-8, MIP-1α and MCP-1). In 12 invasive cancer NAF samples we found a significant positive linear correlation among aluminium, carbonyls and pro-inflammatory IL-6 cytokine (Y = 64.79x-39.63, r(2) 0.8192, p aluminium ions in oxidative and inflammatory status perturbations of breast cancer microenvironment, suggesting aluminium accumulation in breast microenvironment as a possible risk factor for oxidative/inflammatory phenotype of breast cells. © 2013.

  17. Subcellular distribution of nitroblue tetrazolium reductase (NBT-R) in human polymorphonuclear leukocytes (PMN).

    Science.gov (United States)

    Baehner, R L

    1975-11-01

    Subcellular distribution study of cytoplasmic organelles was performed on human polymorphonuclear leukocytes after homogenization in 0.34 molar sucrose by differential centrifugation and sucrose density gradient centrifugation of the homogenate. The whole homogenate and each fraction was assayed for nitroblue tetrazolium (NBT)-reductase with and without 1 mM potassium cyanide, and the distribution of this enzyme was compared to the distribution of lysozyme, peroxidase, beta-glucuronidase, and acid and alkaline phosphatase. Enzyme recovery was 97 per cent and ranged between 74 and 124 per cent. Latent activity of all enzymes except NBT-reductase, acid, and alkaline phosphatase was demonstrated by observing a four- to sixfold increase in activity after the addition of Triton-X 100. Maximal relative specific activity using either DPNH or without cyanide for NBT-reductase was found in the 100,000 x g differential centrifugation fraction and was concentrated in the less dense top fraction of the sucrose density gradient. The distribution pattern was similar to acid and alkaline phosphatase. In contrast, the maximal concentration of beta-glucuronidase and peroxidase was found in the heavier 7,200 x g granule fraction and in the more dense bottom fractions of the sucrose density gradient. Maximal lysozyme activity was concentrated in the 30,000 x g granule fraction and in the fractions located between the heaviest and lightest fractions of the sucrose density gradient. The lack of latent activity and the similarity of subcellular distribution of NBT-reductase to acid and alkaline phosphatase, two enzymes associated with microsomes and plasmalemal membranes in human polymorphonuclear leukocytes (PMN), indicates that NBT-reductase is also a nonlysosomal enzyme located in microsomes or in plasmalemal membranes. These findings support the previously described histochemical observations that initial reduction of NBT to formazan occurs on the PMN plasmalemal surface membrane at

  18. Insights into the redox cycle of human quinone reductase 2.

    Science.gov (United States)

    Reybier, Karine; Perio, Pierre; Ferry, Gilles; Bouajila, Jalloul; Delagrange, Philippe; Boutin, Jean A; Nepveu, Françoise

    2011-10-01

    NRH:quinone oxidoreductase 2 (QR2) is a cytosolic enzyme that catalyzes the reduction of quinones, such as menadione and co-enzymes Q. With the aim of understanding better the mechanisms of action of QR2, we approached this enzyme catalysis via electron paramagnetic resonance (EPR) measurements of the by-products of the QR2 redox cycle. The variation in the production of oxidative species such as H(2)O(2), and subsequent hydroxyl radical generation, was measured during the course of QR2 activity under aerobic conditions and using pure human enzyme. The effects on the activity of the following were compared: (i) synthetic (N-benzyldihydronicotinamide, BNAH) or natural (nicotinamide riboside, NRH) co-substrates; (ii) synthetic (menadione) or natural (co-enzyme Q0, Q2) substrates; (iii) QR2 modulators and inhibitors (melatonin, resveratrol and S29434); (iv) a pro-drug activated via a redox cycle [CB1954, 5-(aziridin-1-yl)-2,4-dinitrobenzamide]. The results were also compared with those obtained with human QR1. The production of hydroxyl radicals is: (i) observed whatever the substrate/co-substrate used; ii) quenched by adding catalase; (iii) not observed with the specific QR2 inhibitor S29434; (iv) observed with the pro-drug CB1954. While QR2 produced free radicals with this pro-drug, QR1 gave no EPR signal showing the strong reducing capacity of QR2. In conclusion, EPR analysis of QR2 enzyme activity through free radical production enables modulators and effective inhibitors to be distinguished. © 2011 Informa UK, Ltd.

  19. The human short-chain dehydrogenase/reductase (SDR) superfamily: a bioinformatics summary.

    Science.gov (United States)

    Bray, James E; Marsden, Brian D; Oppermann, Udo

    2009-03-16

    The short-chain dehydrogenase/reductase (SDR) superfamily represents one of the largest protein superfamilies known to date. Enzymes of this family usually catalyse NAD(P)(H) dependent reactions with a substrate spectrum ranging from polyols, retinoids, steroids and fatty acid derivatives to xenobiotics. We have currently identified 73 SDR superfamily members within the human genome. A status report of the human SDR superfamily is provided in terms of 3D structure determination, co-factor preferences, subcellular localisation and functional annotation. A simple scoring system for measuring structural and functional information (SFS score) has also been introduced to monitor the status of 5 key metrics. Currently there are 17 SDR members with an SFS score of zero indicating that almost a quarter of the human SDR superfamily lacks substantial functional annotation.

  20. Robotic inhibition assay for determination of HMG-CoA reductase inhibitors in human plasma.

    Science.gov (United States)

    Fang, Wei; Liu, Lida; Hsieh, John Y-K; Zhao, Jamie; Matuszewski, Bogdan K; Rogers, John D; Dobrinska, Michael R

    2002-01-01

    The cholesterol-lowering drug simvastatin (SIMV, Zocor reduced heart attacks by 42% in patients who had high cholesterol levels and suffered from heart disease. Upon oral administration, SIMV is quickly hydrolyzed to its beta-hydroxyacid and other acid metabolites, which are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase. A Tecan-based enzyme inhibition assay has been developed to improve the existing Zymark-based assay for the determination of both active and total concentrations of HMG-CoA reductase inhibitors in human plasma. A Tecan Genesis 200 robotic workstation equipped with eight probes and customized hardware was utilized to achieve higher sample throughput and improve assay reproducibility and mechanical stability. The developed enzyme inhibition assay was validated over two concentration ranges of 0.4-20 ng equivalent/mL, and 2-50 ng equivalent/mL. Intra- and interday precision data (coefficient of variation (CV)) for both concentration ranges were less than 9%, with an accuracy of 93-107%. The interday precision for the determination of quality control (QC) samples was less than 2% and 8%, respectively. The respective interday QC accuracy values were 93-103% and 97-104%. Good linearity across the two concentration ranges was observed, with acceptable reproducibility. This improved enzyme inhibition assay has been utilized to analyze human plasma samples from several clinical studies. Copyright 2002 Wiley-Liss, Inc.

  1. Molecular cloning and characterization of a novel Dehydrogenase/reductase (SDR family) member 1 genea from human fetal brain.

    Science.gov (United States)

    Wu, Q; Xu, M; Cheng, C; Zhou, Z; Huang, Y; Zhao, W; Zeng, L; Xu, J; Fu, X; Ying, K; Xie, Y; Mao, Y

    2001-01-01

    Short-chain dehydrogenases/reductases (SDR) constitute a large protein family of NAD(P)(H)-dependent oxidoreductase. They are defined by distinct, common sequence motifs and show a wide range of substrate specialisms. By large-scale sequencing analysis of a human fetal brain cDNA library, we isolated a novel human SDR-type dehydrogenase/reductase gene named Dehydrogenase/reductase (SDR family) member 1 (DHRS1). The DHRS1 cDNA is 1411 base pair in length, encoding a 314-amino-acid polypeptide which has a SDR motif. Northern blot reveals two bands, of about 0.9 and 1.4 kb in size. These two forms are expressed in many tissues. The DHRS1 gene is localized on chromosome 14q21.3. It has 9 exons and spans 9.2 kb of the genomic DNA.

  2. Role of Lysine-54 in determining cofactor specificity and binding in human dihydrofolate reductase

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shaoming; Tan, Xuehai; Thompson, P.D.; Freisheim, J.H. (Medical College of Ohio, Todedo (USA)); Appleman, J.R.; Blakley, R.L. (St. Jude Children' s Research Hospital, Memphis, TN (USA)); Sheridan, R.P.; Venkataraghavan, R. (Lederle Laboratories, Pearl River, NY (USA))

    1990-09-04

    Lysine-54 of human dihydrofolate reductase (hDHFR) appears to be involved in the interaction with the 2{prime}-phosphate of NADPH and is conserved as a basic residue in other species. Studies have suggested that in Lactobacillus casei dihydrofolate reductase Arg-43, the homologous residue at this position, plays an important role in the binding of NADPH and in the differentiation of K{sub m} values for NADPH and NADH. A Lys-54 to Gln-54 mutant (K54Q) of hDHFR has been constructed by oligodeoxynucleotide-directed mutagenesis in order to study the role of Lys-54 in differentiating K{sub m} and k{sub cat} values for NADPH and NADH as well as in other functions of hDHFR. The purpose of this paper is to delineate in quantitative terms the magnitude of the effect of the Lys-54 to Gln-54 replacement on the various kinetic parameters of hDHFR. Such quantitative effects cannot be predicted solely on the basis of X-ray structures. The ratio of K{sub m}(NADH)/K{sub m}(NADPH) decreases from 69 in the wild-type enzyme to 4.7 in the K54Q enzyme, suggesting that Lys-54, among other interactions between protein side-chain residues and the 2{prime}-phosphate, makes a major contribution in terms of binding energy and differentiation of K{sub m} values for NADPH and NADH. Agents at concentrations that show activating effects on the wild-type enzyme such as potassium chloride and urea all inactivate the K54Q enzyme. There appear to be no gross conformational differences between wild-type and K54Q enzyme molecules as judged by competitive ELISA using peptide-specific antibodies against human dihydrofolate reductase and from protease susceptibility studies on both wild-type and K54Q mutant enzymes. The pH-rate profiles using NADPH for K54Q and wild-type enzymes show divergences at certain pH values, suggesting the possibility of alteration(s) in the steps of the catalytic pathway for the K54Q enzyme.

  3. Membrane composition influences the activity of in vitro refolded human vitamin K epoxide reductase.

    Science.gov (United States)

    Jaenecke, Frank; Friedrich-Epler, Beatrice; Parthier, Christoph; Stubbs, Milton T

    2015-10-27

    Human vitamin K epoxide reductase (hVKOR) is an integral membrane protein responsible for the maintenance of reduced vitamin K pools, a prerequisite for the action of γ-glutamyl carboxylase and hence for hemostasis. Here we describe the recombinant expression of hVKOR as an insoluble fusion protein in Escherichia coli, followed by purification and chemical cleavage under denaturing conditions. In vitro renaturation and reconstitution of purified solubilized hVKOR in phospholipids could be established to yield active protein. Crucially, the renatured enzyme is inhibited by the powerful coumarin anticoagulant warfarin, and we demonstrate that enzyme activity depends on lipid composition. The completely synthetic system for protein production allows a rational investigation of the multiple variables in membrane protein folding and paves the way for the provision of pure, active membrane protein for structural studies.

  4. 16th Carbonyl Metabolism Meeting: from enzymology to genomics

    Directory of Open Access Journals (Sweden)

    Maser Edmund

    2012-12-01

    Full Text Available Abstract The 16th International Meeting on the Enzymology and Molecular Biology of Carbonyl Metabolism, Castle of Ploen (Schleswig-Holstein, Germany, July 10–15, 2012, covered all aspects of NAD(P-dependent oxido-reductases that are involved in the general metabolism of xenobiotic and physiological carbonyl compounds. Starting 30 years ago with enzyme purification, structure elucidation and enzyme kinetics, the Carbonyl Society members have meanwhile established internationally recognized enzyme nomenclature systems and now consider aspects of enzyme genomics and enzyme evolution along with their roles in diseases. The 16th international meeting included lectures from international speakers from all over the world.

  5. Association of C677T transition of the human methylenetetrahydrofolate reductase (MTHFR) gene with male infertility.

    Science.gov (United States)

    Karimian, Mohammad; Colagar, Abasalt Hosseinzadeh

    2016-04-01

    The human methylenetetrahydrofolate reductase (MTHFR) gene encodes one of the key enzymes in folate metabolism. This gene is located on chromosome 1 (1p36.3), which has 12 exons. The aim of the present study was to investigate the possible association of the two (C677T and A1298C) polymorphisms of this gene with male infertility. In a case-control study, 250 blood samples were collected from IVF centres in Sari and Babol (Iran): 118 samples were from oligospermic men and 132 were from controls. Two single nucleotide polymorphisms of the MTHFR genotype were detected using polymerase chain reaction-restriction fragment length polymorphism. There was no association found between the A1298C variant and male infertility. However, carriers of the 677T allele (CT and TT genotypes) were at a higher risk of infertility than individuals with other genotypes (odds ratio 1.84; 95% confidence interval 1.11-3.04; P=0.0174). Structural analysis of human MTHFR flavoprotein showed that C677T transition played an important role in the change in affinity of the MTHFR-Flavin adenine dinucleotide binding site. Based on our results, we suggest that C677T transition in MTHFR may increase the risk of male infertility, and detection of the C677T polymorphism biomarker may be helpful in the screening of idiopathic male infertility.

  6. Protein carbonylation in plants

    DEFF Research Database (Denmark)

    Møller, Ian Max; Havelund, Jesper; Rogowska-Wrzesinska, Adelina

    2017-01-01

    This chapter provides an overview of the current knowledge on protein carbonylation in plants and its role in plant physiology. It starts with a brief outline of the turnover and production sites of reactive oxygen species (ROS) in plants and the causes of protein carbonylation. This is followed...... by a description of the methods used to study protein carbonylation in plants, which is also very brief as the methods are similar to those used in studies on animals. The chapter also focuses on protein carbonylation in plants in general and in mitochondria and in seeds in particular, as case stories where...

  7. The Human Biliverdin Reductase-based Peptide Fragments and Biliverdin Regulate Protein Kinase Cδ Activity

    Science.gov (United States)

    Miralem, Tihomir; Lerner-Marmarosh, Nicole; Gibbs, Peter E. M.; Tudor, Cicerone; Hagen, Fred K.; Maines, Mahin D.

    2012-01-01

    PKCδ, a Ser/Thr kinase, promotes cell growth, tumorigenesis, and apoptosis. Human biliverdin reductase (hBVR), a Ser/Thr/Tyr kinase, inhibits apoptosis by reducing biliverdin-IX to antioxidant bilirubin. The enzymes are activated by similar stimuli. Reportedly, hBVR is a kinase-independent activator of PKCδ and is transactivated by the PKC (Gibbs, P. E., Miralem, T., Lerner-Marmarosh, N., Tudor, C., and Maines, M. D. (2012) J. Biol. Chem. 287, 1066–1079). Presently, we examined interactions between the two proteins in the context of regulation of their activities and defining targets of hBVR phosphorylation by PKCδ. LC-MS/MS analysis of PKCδ-activated intact hBVR identified phosphorylated serine positions 21, 33, 230, and 237, corresponding to the hBVR Src homology-2 domain motif (Ser230 and Ser237), flanking the ATP-binding motif (Ser21) and in PHPS sequence (Ser33) as targets of PKCδ. Ser21 and Ser230 were also phosphorylated in hBVR-based peptides. The Ser230-containing peptide was a high affinity substrate for PKCδ in vitro and in cells; the relative affinity was PKCδ > PKCβII > PKCζ. Two overlapping peptides spanning this substrate, KRNRYLSF and SFHFKSGSL, were effective inhibitors of PKCδ kinase activity and PKCδ-supported activation of transcription factors Elk1 and NF-κB. Only SFHFKSGSL, in PKCδ-transfected phorbol 12-myristate 13-acetate-stimulated cells, caused membrane blebbing and cell loss. Biliverdin noncovalently inhibited PKCδ, whereas PKCδ potentiated hBVR reductase activity and accelerated the rate of bilirubin formation. This study, together with previous findings, reveals an unexpected regulatory interplay between PKCδ and hBVR in modulating cell death/survival in response to various activating stimuli. In addition, this study has identified novel substrates for and inhibitors of PKCδ. We suggest that hBVR-based technology may have utility to modulate PKCδ-mediated functions in the cell. PMID:22584576

  8. Evidence that biliverdin-IX beta reductase and flavin reductase are identical.

    OpenAIRE

    Shalloe, F; Elliott, G; Ennis, O; Mantle, T J

    1996-01-01

    A search of the database shows that human biliverdin-IX beta reductase and flavin reductase are identical. We have isolated flavin reductase from bovine erythrocytes and show that the activity co-elutes with biliverdin-IX beta reductase. Preparations of the enzyme that are electrophoretically homogeneous exhibit both flavin reductase and biliverdin-IX beta reductase activities; however, they are not capable of catalysing the reduction of biliverdin-IX alpha. Although there is little obvious s...

  9. SDR-O: an orphan short-chain dehydrogenase/reductase localized at mouse chromosome 10/human chromosome 12.

    Science.gov (United States)

    Chen, Weiguo; Song, Min-Sun; Napoli, Joseph L

    2002-07-10

    We report cloning a cDNA that encodes a novel short-chain dehydrogenase/reductase, SDR-O, conserved in mouse, human and rat. Human and mouse liver express SDR-O (short-chain dehydrogenase/reductase-orphan) mRNA intensely. The mouse embryo expresses SDR-O mRNA as early as day seven. Human SDR-O localizes on chromosome 12; mouse SDR-O localizes on chromosome 10 with CRAD1, CRAD2 and RDH4. SDR-O shares highest amino acid similarity with rat RoDH1 and mouse RDH1 (69-70%), but does not have the retinol and 3alpha-hydroxysteroid dehydrogenase activity of either, nor is it active as a 17beta- or 11beta-hydroxysteroid dehydrogenase. Short-chain dehydrogenase/reductases catalyse the metabolism of ligands that bind with nuclear receptors: the occurrence of 'orphan' nuclear receptors may imply existence of 'orphan' SDR, suggesting that SDR-O may catalyse the metabolism of another class of nuclear receptor ligand. Alternatively, SDR-O may not have a catalytic function, but may regulate metabolism by binding substrates/products and/or by serving as a regulatory factor.

  10. Involvement of ribonucleotide reductase M1 subunit overexpression in gemcitabine resistance of human pancreatic cancer.

    Science.gov (United States)

    Nakahira, Shin; Nakamori, Shoji; Tsujie, Masanori; Takahashi, Yuji; Okami, Jiro; Yoshioka, Shinichi; Yamasaki, Makoto; Marubashi, Shigeru; Takemasa, Ichiro; Miyamoto, Atsushi; Takeda, Yutaka; Nagano, Hiroaki; Dono, Keizo; Umeshita, Koji; Sakon, Masato; Monden, Morito

    2007-03-15

    Pancreatic cancer is the most lethal of all solid tumors partially because of its chemoresistance. Although gemcitabine is widely used as a first selected agent for the treatment of this disease despite low response rate, molecular mechanisms of gemcitabine resistance in pancreatic cancer still remain obscure. The aim of this study is to elucidate the mechanisms of gemcitabine resistance. The 81-fold gemcitabine resistant variant MiaPaCa2-RG was selected from pancreatic cancer cell line MiaPaCa2. By microarray analysis between MiaPaCa2 and MiaPaCa2-RG, 43 genes (0.04%) were altered expression of more than 2-fold. The most upregulated gene in MiaPaCa2-RG was ribonucleotide reductase M1 subunit (RRM1) with 4.5-fold up-regulation. Transfection with RRM1-specific RNAi suppressed more than 90% of RRM1 mRNA and protein expression. After RRM1-specific RNAi transfection, gemcitabine chemoresistance of MiaPaCa2-RG was reduced to the same level of MiaPaCa2. The 18 recurrent pancreatic cancer patients treated by gemcitabine were divided into 2 groups by RRM1 levels. There was a significant association between gemcitabine response and RRM1 expression (p = 0.018). Patients with high RRM1 levels had poor survival after gemcitabine treatment than those with low RRM1 levels (p = 0.016). RRM1 should be a key molecule in gemcitabine resistance in human pancreatic cancer through both in vitro and clinical models. RRM1 may have the potential as predictor and modulator of gemcitabine treatment. (c) 2006 Wiley-Liss, Inc.

  11. The effect of methylenetetrahydrofolate reductase polymorphisms on susceptibility to human papilloma virus infection and cervical cancer.

    Science.gov (United States)

    Hajiesmaeil, Mogge; Tafvizi, Farzaneh; Sarmadi, Soheila

    2016-12-01

    Cervical cancer is the third most common cancer among women worldwide. Several factors lead to cervical cancer, among which human papilloma virus (HPV) infection has a prominent role. Methylenetetrahydrofolate reductase (MTHFR) is crucial in folate metabolic pathway and plays an important role in DNA synthesis and DNA methylation. MTHFR gene polymorphisms, including C677T and A1298C, lead to reduced enzyme activity. This case-control study aims to illustrate the association between MTHFR gene polymorphisms and the risk of cervical cancer. This study was conducted on 196 samples, which included 96 cervical biopsy samples compared to 100 Pap smear samples of normal healthy women without HPV infection. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used for the MTHFR polymorphism detection, followed by fluorescent amplification-based specific hybridization PCR method to detect HPV16 and HPV18. The results show that the MTHFR 677TT genotype plays a protective role in cervical cancer (P=0.0030) (OR=0.21, 95% confidence interval [CI]: 0.07-0.59). Furthermore, there was a strong significant association between MTHFR 1298CC genotype and the risk of cervical cancer (OR=10.69; 95% CI: 4.28-26.71, P=0.0001). It can be concluded that A1298C polymorphism is a genetic risk factor for cervical cancer in the assessed Iranian population group. It seems that MTHFR 1298CC genotype is more susceptible to HPV 16 infection. Combination analysis of MTHFR C677T and A1298C polymorphisms revealed that combined MTHFR 677CC and 1298CC are strongly associated with a risk of cervical cancer. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. A-to-I RNA Editing Up-regulates Human Dihydrofolate Reductase in Breast Cancer.

    Science.gov (United States)

    Nakano, Masataka; Fukami, Tatsuki; Gotoh, Saki; Nakajima, Miki

    2017-03-24

    Dihydrofolate reductase (DHFR) plays a key role in folate metabolism and is a target molecule of methotrexate. An increase in the cellular expression level of DHFR is one of the mechanisms of tumor resistance to methotrexate. The present study investigated the possibility that adenosine-to-inosine RNA editing, which causes nucleotide conversion by adenosine deaminase acting on RNA (ADAR) enzymes, might modulate DHFR expression. In human breast adenocarcinoma-derived MCF-7 cells, 26 RNA editing sites were identified in the 3'-UTR of DHFR. Knockdown of ADAR1 decreased the RNA editing levels of DHFR and resulted in a decrease in the DHFR mRNA and protein levels, indicating that ADAR1 up-regulates DHFR expression. Using a computational analysis, miR-25-3p and miR-125a-3p were predicted to bind to the non-edited 3'-UTR of DHFR but not to the edited sequence. The decrease in DHFR expression by the knockdown of ADAR1 was restored by transfection of antisense oligonucleotides for these miRNAs, suggesting that RNA editing mediated up-regulation of DHFR requires the function of these miRNAs. Interestingly, we observed that the knockdown of ADAR1 decreased cell viability and increased the sensitivity of MCF-7 cells to methotrexate. ADAR1 expression levels and the RNA editing levels in the 3'-UTR of DHFR in breast cancer tissues were higher than those in adjacent normal tissues. Collectively, the present study demonstrated that ADAR1 positively regulates the expression of DHFR by editing the miR-25-3p and miR-125a-3p binding sites in the 3'-UTR of DHFR, enhancing cellular proliferation and resistance to methotrexate. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Expression and characterization of truncated human heme oxygenase (hHO-1) and a fusion protein of hHO-1 with human cytochrome P450 reductase.

    Science.gov (United States)

    Wilks, A; Black, S M; Miller, W L; Ortiz de Montellano, P R

    1995-04-04

    A human heme oxygenase (hHO-1) gene without the sequence coding for the last 23 amino acids has been expressed in Escherichia coli behind the pho A promoter. The truncated enzyme is obtained in high yields as a soluble, catalytically-active protein, making it available for the first time for detailed mechanistic studies. The purified, truncated hHO-1/heme complex is spectroscopically indistinguishable from that of the rat enzyme and converts heme to biliverdin when reconstituted with rat liver cytochrome P450 reductase. A self-sufficient heme oxygenase system has been obtained by fusing the truncated hHO-1 gene to the gene for human cytochrome P450 reductase without the sequence coding for the 20 amino acid membrane binding domain. Expression of the fusion protein in pCWori+ yields a protein that only requires NADPH for catalytic turnover. The failure of exogenous cytochrome P450 reductase to stimulate turnover and the insensitivity of the catalytic rate toward changes in ionic strength establish that electrons are transferred intramolecularly between the reductase and heme oxygenase domains of the fusion protein. The Vmax for the fusion protein is 2.5 times higher than that for the reconstituted system. Therefore, either the covalent tether does not interfere with normal docking and electron transfer between the flavin and heme domains or alternative but equally efficient electron transfer pathways are available that do not require specific docking.

  14. The 5 Alpha-Reductase Isozyme Family: A Review of Basic Biology and Their Role in Human Diseases

    Directory of Open Access Journals (Sweden)

    Faris Azzouni

    2012-01-01

    Full Text Available Despite the discovery of 5 alpha-reduction as an enzymatic step in steroid metabolism in 1951, and the discovery that dihydrotestosterone is more potent than testosterone in 1968, the significance of 5 alpha-reduced steroids in human diseases was not appreciated until the discovery of 5 alpha-reductase type 2 deficiency in 1974. Affected males are born with ambiguous external genitalia, despite normal internal genitalia. The prostate is hypoplastic, nonpalpable on rectal examination and approximately 1/10th the size of age-matched normal glands. Benign prostate hyperplasia or prostate cancer does not develop in these patients. At puberty, the external genitalia virilize partially, however, secondary sexual hair remains sparse and male pattern baldness and acne develop rarely. Several compounds have been developed to inhibit the 5 alpha-reductase isozymes and they play an important role in the prevention and treatment of many common diseases. This review describes the basic biochemical properties, functions, tissue distribution, chromosomal location, and clinical significance of the 5 alpha-reductase isozyme family.

  15. Inhibition of Human Steroid 5-Reductase (AKR1D1) by Finasteride and Structure of the Enzyme-Inhibitor Complex

    Energy Technology Data Exchange (ETDEWEB)

    Drury, J.; Di Costanzo, L; Penning, T; Christianson, D

    2009-01-01

    The {Delta}{sup 4}-3-ketosteroid functionality is present in nearly all steroid hormones apart from estrogens. The first step in functionalization of the A-ring is mediated in humans by steroid 5{alpha}- or 5{beta}-reductase. Finasteride is a mechanism-based inactivator of 5{alpha}-reductase type 2 with subnanomolar affinity and is widely used as a therapeutic for the treatment of benign prostatic hyperplasia. It is also used for androgen deprivation in hormone-dependent prostate carcinoma, and it has been examined as a chemopreventive agent in prostate cancer. The effect of finasteride on steroid 5{beta}-reductase (AKR1D1) has not been previously reported. We show that finasteride competitively inhibits AKR1D1 with low micromolar affinity but does not act as a mechanism-based inactivator. The structure of the AKR1D1 {center_dot} NADP{sup +} {center_dot} finasteride complex determined at 1.7 {angstrom} resolution shows that it is not possible for NADPH to reduce the {Delta}{sup 1-2}-ene of finasteride because the cofactor and steroid are not proximal to each other. The C3-ketone of finasteride accepts hydrogen bonds from the catalytic residues Tyr-58 and Glu-120 in the active site of AKR1D1, providing an explanation for the competitive inhibition observed. This is the first reported structure of finasteride bound to an enzyme involved in steroid hormone metabolism.

  16. Overexpression and enhanced specific activity of aldoketo reductases (AKR1B1 & AKR1B10) in human breast cancers.

    Science.gov (United States)

    Reddy, K Ashok; Kumar, P Uday; Srinivasulu, M; Triveni, B; Sharada, K; Ismail, Ayesha; Reddy, G Bhanuprakash

    2017-02-01

    The incidence of breast cancer in India is on the rise and is rapidly becoming the primary cancer in Indian women. The aldoketo reductase (AKR) family has more than 190 proteins including aldose reductase (AKR1B1) and aldose reductase like protein (AKR1B10). Apart from liver cancer, the status of AKR1B1 and AKR1B10 with respect to their expression and activity has not been reported in other human cancers. We studied the specific activity and expression of AKR1B1 and AKR1B10 in breast non tumor and tumor tissues and in the blood. Fresh post-surgical breast cancer and non-cancer tissues and blood were collected from the subjects who were admitted for surgical therapy. Malignant, benign and pre-surgical chemotherapy samples were evaluated by histopathology scoring. Expression of AKR1B1 and AKR1B10 was carried out by immunoblotting and immunohistochemistry (IHC) while specific activity was determined spectrophotometrically. The specific activity of AKR1B1 was significantly higher in red blood cells (RBC) in all three grades of primary surgical and post-chemotherapy samples. Specific activity of both AKR1B1 and AKR1B10 increased in tumor samples compared to their corresponding non tumor samples (primary surgical and post-chemotherapy). Immunoblotting and IHC data also indicated overexpression of AKR1B1 in all grades of tumors compared to their corresponding non tumor samples. There was no change in the specific activity of AKR1B1 in benign samples compared to all grades of tumor and non-tumors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Exploration of natural product ingredients as inhibitors of human HMG-CoA reductase through structure-based virtual screening

    Directory of Open Access Journals (Sweden)

    Lin SH

    2015-06-01

    Full Text Available Shih-Hung Lin,1 Kao-Jean Huang,1,2 Ching-Feng Weng,1 David Shiuan1 1Department of Life Science and Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan, Republic of China; 2Development Center of Biotechnology, Taipei, Taiwan, Republic of China Abstract: Cholesterol plays an important role in living cells. However, a very high level of cholesterol may lead to atherosclerosis. HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A reductase is the key enzyme in the cholesterol biosynthesis pathway, and the statin-like drugs are inhibitors of human HMG-CoA reductase (hHMGR. The present study aimed to virtually screen for potential hHMGR inhibitors from natural product to discover hypolipidemic drug candidates with fewer side effects and lesser toxicities. We used the 3D structure 1HWK from the PDB (Protein Data Bank database of hHMGR as the target to screen for the strongly bound compounds from the traditional Chinese medicine database. Many interesting molecules including polyphenolic compounds, polisubstituted heterocyclics, and linear lipophilic alcohols were identified and their ADMET (absorption, disrtibution, metabolism, excretion, toxicity properties were predicted. Finally, four compounds were obtained for the in vitro validation experiments. The results indicated that curcumin and salvianolic acid C can effectively inhibit hHMGR, with IC50 (half maximal inhibitory concentration values of 4.3 µM and 8 µM, respectively. The present study also demonstrated the feasibility of discovering new drug candidates through structure-based virtual screening. Keywords: HMG-CoA reductase, virtual screening, curcumin, salvianolic acid C

  18. Genetic variation of Aflatoxin B(1) aldehyde reductase genes (AFAR) in human tumour cells

    DEFF Research Database (Denmark)

    Praml, Christian; Schulz, Wolfgang; Claas, Andreas

    2008-01-01

    AFAR genes play a key role in the detoxification of the carcinogen Aflatoxin B(1) (AFB(1)). In the rat, Afar1 induction can prevent AFB(1)-induced liver cancer. It has been proposed that AFAR enzymes can metabolise endogenous diketones and dialdehydes that may be cytotoxic and/or genotoxic. Furth...... many aldo-keto reductases. This polarity change may have an effect on the proposed substrate binding amino acids nearby (Met(47), Tyr(48), Asp(50)). Further population analyses and functional studies of the nine variants detected may show if these variants are disease-related....

  19. Towards a systematic analysis of human short-chain dehydrogenases/reductases (SDR): Ligand identification and structure-activity relationships.

    Science.gov (United States)

    Bhatia, Chitra; Oerum, Stephanie; Bray, James; Kavanagh, Kathryn L; Shafqat, Naeem; Yue, Wyatt; Oppermann, Udo

    2015-06-05

    Short-chain dehydrogenases/reductases (SDRs) constitute a large, functionally diverse branch of enzymes within the class of NAD(P)(H) dependent oxidoreductases. In humans, over 80 genes have been identified with distinct metabolic roles in carbohydrate, amino acid, lipid, retinoid and steroid hormone metabolism, frequently associated with inherited genetic defects. Besides metabolic functions, a subset of atypical SDR proteins appears to play critical roles in adapting to redox status or RNA processing, and thereby controlling metabolic pathways. Here we present an update on the human SDR superfamily and a ligand identification strategy using differential scanning fluorimetry (DSF) with a focused library of oxidoreductase and metabolic ligands to identify substrate classes and inhibitor chemotypes. This method is applicable to investigate structure-activity relationships of oxidoreductases and ultimately to better understand their physiological roles. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. Exploration of natural product ingredients as inhibitors of human HMG-CoA reductase through structure-based virtual screening.

    Science.gov (United States)

    Lin, Shih-Hung; Huang, Kao-Jean; Weng, Ching-Feng; Shiuan, David

    2015-01-01

    Cholesterol plays an important role in living cells. However, a very high level of cholesterol may lead to atherosclerosis. HMG-CoA (3-hydroxy-3-methylglutaryl coenzyme A) reductase is the key enzyme in the cholesterol biosynthesis pathway, and the statin-like drugs are inhibitors of human HMG-CoA reductase (hHMGR). The present study aimed to virtually screen for potential hHMGR inhibitors from natural product to discover hypolipidemic drug candidates with fewer side effects and lesser toxicities. We used the 3D structure 1HWK from the PDB (Protein Data Bank) database of hHMGR as the target to screen for the strongly bound compounds from the traditional Chinese medicine database. Many interesting molecules including polyphenolic compounds, polisubstituted heterocyclics, and linear lipophilic alcohols were identified and their ADMET (absorption, disrtibution, metabolism, excretion, toxicity) properties were predicted. Finally, four compounds were obtained for the in vitro validation experiments. The results indicated that curcumin and salvianolic acid C can effectively inhibit hHMGR, with IC50 (half maximal inhibitory concentration) values of 4.3 µM and 8 µM, respectively. The present study also demonstrated the feasibility of discovering new drug candidates through structure-based virtual screening.

  1. Human heme oxygenase-1 efficiently catabolizes heme in the absence of biliverdin reductase.

    Science.gov (United States)

    Reed, James R; Huber, Warren J; Backes, Wayne L

    2010-11-01

    Heme oxygenase 1 (HO-1) uses molecular oxygen and electrons from NADPH cytochrome P450 reductase to convert heme to CO, ferrous iron, and biliverdin (BV). Enzymatic studies with the purified 30-kDa form of HO-1 routinely use a coupled assay containing biliverdin reductase (BVR), which converts BV to bilirubin (BR). BVR is believed to be required for optimal HO-1 activity. The goal of this study was to determine whether HO-1 activity could be monitored directly by following BV generation or iron release (using the ferrous iron chelator, ferrozine) in the absence of BVR. Using assays for each of the three end products, we found that HO-1 activity was stimulated in the presence of catalase and comparable rates were measured with each assay. Absorbance scans revealed characteristic spectra for BR, BV, and/or the ferrozine-iron complex. The optimal conditions were slightly different for the direct and coupled assays. BSA activated the coupled but inhibited the direct assays, and the assays had different pH optima. By measuring the activity of BVR directly using BV as a substrate, these differences were attributed to different enzymatic properties of BVR and HO-1. Thus, BVR is not needed to measure the activity of HO-1 when catalase is present. In fact, the factors affecting catalysis by HO-1 are better understood using the direct assays because the coupled assay can be influenced by properties of BVR.

  2. Reciprocal carbonyl-carbonyl interactions in small molecules and proteins.

    Science.gov (United States)

    Rahim, Abdur; Saha, Pinaki; Jha, Kunal Kumar; Sukumar, Nagamani; Sarma, Bani Kanta

    2017-07-19

    Carbonyl-carbonyl n→π* interactions where a lone pair (n) of the oxygen atom of a carbonyl group is delocalized over the π* orbital of a nearby carbonyl group have attracted a lot of attention in recent years due to their ability to affect the 3D structure of small molecules, polyesters, peptides, and proteins. In this paper, we report the discovery of a "reciprocal" carbonyl-carbonyl interaction with substantial back and forth n→π* and π→π* electron delocalization between neighboring carbonyl groups. We have carried out experimental studies, analyses of crystallographic databases and theoretical calculations to show the presence of this interaction in both small molecules and proteins. In proteins, these interactions are primarily found in polyproline II (PPII) helices. As PPII are the most abundant secondary structures in unfolded proteins, we propose that these local interactions may have implications in protein folding.Carbonyl-carbonyl π* non covalent interactions affect the structure and stability of small molecules and proteins. Here, the authors carry out experimental studies, analyses of crystallographic databases and theoretical calculations to describe an additional type of carbonyl-carbonyl interaction.

  3. Altered heme catabolism by heme oxygenase-1 caused by mutations in human NADPH cytochrome P450 reductase

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Amit V., E-mail: amit@pandeylab.org [Pediatric Endocrinology, Diabetology and Metabolism, Department of Clinical Research, University of Bern, Tiefenaustrasse 120c, CH-3004 Bern (Switzerland); Flueck, Christa E.; Mullis, Primus E. [Pediatric Endocrinology, Diabetology and Metabolism, Department of Clinical Research, University of Bern, Tiefenaustrasse 120c, CH-3004 Bern (Switzerland)

    2010-09-24

    Research highlights: {yields} Mutations in POR identified from patients lead to reduced HO-1 activities. {yields} POR mutation Y181D affecting FMN binding results in total loss of HO-1 activity. {yields} POR mutations A287P, C569Y and V608F, lost 50-70% activity. {yields} Mutations in FAD binding domain, R457H, Y459H and V492E lost all HO-1 activity. {yields} POR polymorphisms P228L, R316W, G413S, A503V and G504R have normal activity. -- Abstract: Human heme oxygenase-1 (HO-1) carries out heme catabolism supported by electrons supplied from the NADPH through NADPH P450 reductase (POR, CPR). Previously we have shown that mutations in human POR cause a rare form of congenital adrenal hyperplasia. In this study, we have evaluated the effects of mutations in POR on HO-1 activity. We used purified preparations of wild type and mutant human POR and in vitro reconstitution with purified HO-1 to measure heme degradation in a coupled assay using biliverdin reductase. Here we show that mutations in POR found in patients may reduce HO-1 activity, potentially influencing heme catabolism in individuals carrying mutant POR alleles. POR mutants Y181D, A457H, Y459H, V492E and R616X had total loss of HO-1 activity, while POR mutations A287P, C569Y and V608F lost 50-70% activity. The POR variants P228L, R316W and G413S, A503V and G504R identified as polymorphs had close to WT activity. Loss of HO-1 activity may result in increased oxidative neurotoxicity, anemia, growth retardation and iron deposition. Further examination of patients affected with POR deficiency will be required to assess the metabolic effects of reduced HO-1 activity in affected individuals.

  4. Inhibitors of Human Dihydrofolate Reductase: A Computational Design and Docking Studies Using Glide

    Directory of Open Access Journals (Sweden)

    Lingala Yamini

    2008-01-01

    Full Text Available Dihydrofolate reductase (DHFR plays a vital role in the DNA synthesis by reducing dihydrofolic acid to tetrahydrofolic acid which is an essential component. Synthetic ligands like methotrexate (MTX, aminopterin (AMP and their analogues act as potential anti metabolites by mimicking the coenzyme dihydrofolic acid (DHFA they inhibit the activity of DHFR antagonistically. Several ligands which are similar to MTX analogues and 6, 8 substituted 2 – naphthyls (NAP which can mimic the pteridyl group of DHFA have been computationally designed. These ligands were proposed to hinder the formation N5, N10 methylene tetrahydrofolic acid (THFA coenzyme, which is essential for the DNA synthesis. The docking studies were done using grid, generated with the 0.9 Vander Waals scaling for non polar bonds in the active site of the receptor. These newly designed ligands such as 14 -21 ,23 and 28 have shown good docking scores and predicted activities when compared to already existing ligands MTX and its analogues.

  5. The Hinge Segment of Human NADPH-Cytochrome P450 Reductase in Conformational Switching: The Critical Role of Ionic Strength

    Directory of Open Access Journals (Sweden)

    Diana Campelo

    2017-10-01

    Full Text Available NADPH-cytochrome P450 reductase (CPR is a redox partner of microsomal cytochromes P450 and is a prototype of the diflavin reductase family. CPR contains 3 distinct functional domains: a FMN-binding domain (acceptor reduction, a linker (hinge, and a connecting/FAD domain (NADPH oxidation. It has been demonstrated that the mechanism of CPR exhibits an important step in which it switches from a compact, closed conformation (locked state to an ensemble of open conformations (unlocked state, the latter enabling electron transfer to redox partners. The conformational equilibrium between the locked and unlocked states has been shown to be highly dependent on ionic strength, reinforcing the hypothesis of the presence of critical salt interactions at the interface between the FMN and connecting FAD domains. Here we show that specific residues of the hinge segment are important in the control of the conformational equilibrium of CPR. We constructed six single mutants and two double mutants of the human CPR, targeting residues G240, S243, I245 and R246 of the hinge segment, with the aim of modifying the flexibility or the potential ionic interactions of the hinge segment. We measured the reduction of cytochrome c at various salt concentrations of these 8 mutants, either in the soluble or membrane-bound form of human CPR. All mutants were found capable of reducing cytochrome c yet with different efficiency and their maximal rates of cytochrome c reduction were shifted to lower salt concentration. In particular, residue R246 seems to play a key role in a salt bridge network present at the interface of the hinge and the connecting domain. Interestingly, the effects of mutations, although similar, demonstrated specific differences when present in the soluble or membrane-bound context. Our results demonstrate that the electrostatic and flexibility properties of the hinge segment are critical for electron transfer from CPR to its redox partners.

  6. Human dihydrofolate reductase and thymidylate synthase form a complex in vitro and co-localize in normal and cancer cells.

    Science.gov (United States)

    Antosiewicz, Anna; Jarmuła, Adam; Przybylska, Dorota; Mosieniak, Grażyna; Szczepanowska, Joanna; Kowalkowska, Anna; Rode, Wojciech; Cieśla, Joanna

    2017-05-01

    Enzymes involved in thymidylate biosynthesis, thymidylate synthase (TS), and dihydrofolate reductase (DHFR) are well-known targets in cancer chemotherapy. In this study, we demonstrated for the first time, that human TS and DHFR form a strong complex in vitro and co-localize in human normal and colon cancer cell cytoplasm and nucleus. Treatment of cancer cells with methotrexate or 5-fluorouracil did not affect the distribution of either enzyme within the cells. However, 5-FU, but not MTX, lowered the presence of DHFR-TS complex in the nucleus by 2.5-fold. The results may suggest the sequestering of TS by FdUMP in the cytoplasm and thereby affecting the translocation of DHFR-TS complex to the nucleus. Providing a strong likelihood of DHFR-TS complex formation in vivo, the latter complex is a potential new drug target in cancer therapy. In this paper, known 3D structures of human TS and human DHFR, and some protozoan bifunctional DHFR-TS structures as templates, are used to build an in silico model of human DHFR-TS complex structure, consisting of one TS dimer and two DHFR monomers. This complex structure may serve as an initial 3D drug target model for prospective inhibitors targeting interfaces between the DHFR and TS enzymes.

  7. ANAEROBIC VS. AEROBIC PATHWAYS OF CARBONYL AND OXIDANT STRESS IN HUMAN LENS AND SKIN DURING AGING AND IN DIABETES: A COMPARATIVE ANALYSIS

    Science.gov (United States)

    Fan, Xingjun; Sell, David R; Zhang, Jianye; Nemet, Ina; Theves, Mathilde; Lu, Jie; Strauch, Christopher; Halushka, Marc K.; Monnier, Vincent M.

    2010-01-01

    The effects of anaerobic (lens) vs aerobic (skin) environment on carbonyl and oxidant stress are compared using de novo and existing data on advanced glycation and oxidation products in human crystallins and collagen. Almost all modifications increase with age. Methylglyoxal hydroimidazolones (MG-H1), carboxymethyl-lysine (CML), and carboxyethyl-lysine (CEL) are several folds higher in lens than skin, and markedly increase upon incubation of lens crystallins with 5 mM ascorbic acid. Vice-versa, fructose-lysine, glucosepane crosslinks, glyoxal hydroimidazolones (G-H1), metal catalyzed oxidation (allysine) and H2O2 dependent modifications (2-aminoapidic acid and methionine sulfoxide) are markedly elevated in skin, but relatively suppressed in the aging lens. In both tissues ornithine is the dominant modification, implicating arginine residues as the principal target of the Maillard reaction in vivo. Diabetes (here mostly type 2 studied) increases significantly fructose-lysine and glucosepane in both tissues (Pascorbate is predominant in the aging non-cataractous lens, while aging skin collagen undergoes combined attack by non-oxidative glucose mediated modifications, as well as those from metal catalyzed oxidation and H2O2. PMID:20541005

  8. Anaerobic vs aerobic pathways of carbonyl and oxidant stress in human lens and skin during aging and in diabetes: A comparative analysis.

    Science.gov (United States)

    Fan, Xingjun; Sell, David R; Zhang, Jianye; Nemet, Ina; Theves, Mathilde; Lu, Jie; Strauch, Christopher; Halushka, Marc K; Monnier, Vincent M

    2010-09-01

    The effects of anaerobic (lens) vs aerobic (skin) environment on carbonyl and oxidant stress are compared using de novo and existing data on advanced glycation and oxidation products in human crystallins and collagen. Almost all modifications increase with age. Methylglyoxal hydroimidazolones, carboxymethyllysine, and carboxyethyllysine are severalfold higher in lens than in skin and markedly increase upon incubation of lens crystallins with 5mM ascorbic acid. In contrast, fructose-lysine, glucosepane crosslinks, glyoxal hydroimidazolones, metal-catalyzed oxidation (allysine), and H(2)O(2)-dependent modifications (2-aminoapidic acid and methionine sulfoxide) are markedly elevated in skin, but relatively suppressed in the aging lens. In both tissues ornithine is the dominant modification, implicating arginine residues as the principal target of the Maillard reaction in vivo. Diabetes (here mostly type 2 studied) increases significantly fructose-lysine and glucosepane in both tissues (Pdiabetes strengthens the Spearman correlation coefficients for age-related accumulation of hydrogen peroxide-mediated modifications in the lens. Overall, the data suggest that oxoaldehyde stress involving methylglyoxal from either glucose or ascorbate is predominant in the aging noncataractous lens, whereas aging skin collagen undergoes combined attack by nonoxidative glucose-mediated modifications, as well as those from metal-catalyzed oxidation and H(2)O(2). Copyright 2010 Elsevier Inc. All rights reserved.

  9. New evidence of similarity between human and plant steroid metabolism: 5alpha-reductase activity in Solanum malacoxylon.

    Science.gov (United States)

    Rosati, Fabiana; Danza, Giovanna; Guarna, Antonio; Cini, Nicoletta; Racchi, Milvia Luisa; Serio, Mario

    2003-01-01

    The physiological role of steroid hormones in humans is well known, and the metabolic pathway and mechanisms of action are almost completely elucidated. The role of plant steroid hormones, brassinosteroids, is less known, but an increasing amount of data on brassinosteroid biosynthesis is showing unexpected similarities between human and plant steroid metabolic pathways. Here we focus our attention on the enzyme 5alpha-reductase (5alphaR) for which a plant ortholog of the mammalian system, DET2, was recently described in Arabidopsis thaliana. We demonstrate that campestenone, the natural substrate of DET2, is reduced to 5alpha-campestanone by both human 5alphaR isozymes but with different affinities. Solanum malacoxylon, which is a calcinogenic plant very active in the biosynthesis of vitamin D-like molecules and sterols, was used to study 5alphaR activity. Leaves and calli were chosen as examples of differentiated and undifferentiated tissues, respectively. Two separate 5alphaR activities were found in calli and leaves of Solanum using campestenone as substrate. The use of progesterone allowed the detection of both activities in calli. Support for the existence of two 5alphaR isozymes in S. malacoxylon was provided by the differential actions of inhibitors of the human 5alphaR in calli and leaves. The evidence for the presence of two isozymes in different plant tissues extends the analogies between plant and mammalian steroid metabolic pathways.

  10. Biliverdin inhibits activation of NF-kappaB: reversal of inhibition by human biliverdin reductase.

    Science.gov (United States)

    Gibbs, Peter E M; Maines, Mahin D

    2007-12-01

    hBVR functions in the cell as a reductase and as a kinase. In the first capacity, it reduces biliverdin, the product of HO activity, to the effective intracellular antioxidant, bilirubin; as a dual-specificity kinase (S/T/Y) it activates the MAPK and IGF/IRK receptor signal transduction pathways. NF-kappaB and the MAPK pathway are activated by ROS, which results in the activation of stress-inducible genes, including ho-1. Presently, we report on the negative effect of biliverdin on NF-kappaB activation and the converse effect of hBVR. Biliverdin, in a concentration- and time-dependent manner, inhibited transcriptional activity of NF-kappaB in HEK293A cells. Nuclear extracts from biliverdin-treated cells show reduced DNA binding of NF-kappaB in an electromobility shift assay, whereas extracts from cells treated with TNF-alpha showed enhanced binding. Coimmunoprecipitation data show hBVR binds to the 65 kDa subunit of NF-kappaB, and that this is dependent on activation by TNF-alpha. Overexpression of hBVR enhanced both the basal and TNF-alpha-mediated activation of NF-kappaB and also that of the NF-kappaB-activated iNOS gene. Also, overexpression of hBVR arrested the cell cycle in the G(1)/G(0) phase and reduced the number of cells in S phase. Similar results were observed with MCF-7 cells. Because of the Janus nature of NF-kappaB activity in the cell and the inhibitory action of biliverdin, the present findings provide a foundation for therapeutic intervention in inflammatory diseases and cancer that may be attained by preventing reduction of biliverdin. On the other hand, by increasing BVR levels beneficial functions of NF-kappaB might be augmented. (c) 2007 Wiley-Liss, Inc.

  11. Human dehydrogenase/reductase (SDR family) member 11 is a novel type of 17β-hydroxysteroid dehydrogenase.

    Science.gov (United States)

    Endo, Satoshi; Miyagi, Namiki; Matsunaga, Toshiyuki; Hara, Akira; Ikari, Akira

    2016-03-25

    We report characterization of a member of the short-chain dehydrogenase/reductase superfamily encoded in a human gene, DHRS11. The recombinant protein (DHRS11) efficiently catalyzed the conversion of the 17-keto group of estrone, 4- and 5-androstenes and 5α-androstanes into their 17β-hydroxyl metabolites with NADPH as a coenzyme. In contrast, it exhibited reductive 3β-hydroxysteroid dehydrogenase activity toward 5β-androstanes, 5β-pregnanes, 4-pregnenes and bile acids. Additionally, DHRS11 reduced α-dicarbonyls (such as diacetyl and methylglyoxal) and alicyclic ketones (such as 1-indanone and loxoprofen). The enzyme activity was inhibited in a mixed-type manner by flavonoids, and competitively by carbenoxolone, glycyrrhetinic acid, zearalenone, curcumin and flufenamic acid. The expression of DHRS11 mRNA was observed widely in human tissues, most abundantly in testis, small intestine, colon, kidney and cancer cell lines. Thus, DHRS11 represents a novel type of 17β-hydroxysteroid dehydrogenase with unique catalytic properties and tissue distribution. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Resveratrol preconditioning increases methionine sulfoxide reductases A expression and enhances resistance of human neuroblastoma cells to neurotoxins.

    Science.gov (United States)

    Wu, Peng-Fei; Xie, Na; Zhang, Juan-Juan; Guan, Xin-Lei; Zhou, Jun; Long, Li-Hong; Li, Yuan-Long; Xiong, Qiu-Ju; Zeng, Jian-Hua; Wang, Fang; Chen, Jian-Guo

    2013-06-01

    Methionine sulfoxide reductases A (MsrA) has been postulated to act as a catalytic antioxidant system involved in the protection of oxidative stress-induced cell injury. Recently, attention has turned to MsrA in coupling with the pathology of Parkinson's disease, which is closely related to neurotoxins that cause dopaminergic neuron degeneration. Here, we firstly provided evidence that pretreatment with a natural polyphenol resveratrol (RSV) up-regulated the expression of MsrA in human neuroblastoma SH-SY5Y cells. It was also observed that the expression and nuclear translocation of forkhead box group O 3a (FOXO3a), a transcription factor that activates the human MsrA promoter, increased after RSV pretreatment. Nicotinamide , an inhibitor of silent information regulator 1 (SIRT1), prevented RSV-induced elevation of FOXO3a and MsrA expression, indicating that the effect of RSV was mediated by a SIRT1-dependent pathway. RSV preconditioning increased methionine sulfoxide(MetO)-reducing activity in SH-SY5Y cells and enhanced their resistance to neurotoxins, including chloramine-T and 1-methyl-4-phenyl-pyridinium. In addition, the enhancement of cell resistance to neurotoxins caused by RSV preconditioning can be largely prevented by MsrA inhibitor dimethyl sulfoxide. Our findings suggest that treatment with polyphenols such as RSV can be used as a potential regulatory strategy for MsrA expression and function. Copyright © 2013 Elsevier Inc. All rights reserved.

  13. Evidence that biliverdin-IX beta reductase and flavin reductase are identical.

    Science.gov (United States)

    Shalloe, F; Elliott, G; Ennis, O; Mantle, T J

    1996-01-01

    A search of the database shows that human biliverdin-IX beta reductase and flavin reductase are identical. We have isolated flavin reductase from bovine erythrocytes and show that the activity co-elutes with biliverdin-IX beta reductase. Preparations of the enzyme that are electrophoretically homogeneous exhibit both flavin reductase and biliverdin-IX beta reductase activities; however, they are not capable of catalysing the reduction of biliverdin-IX alpha. Although there is little obvious sequence identity between biliverdin-IX alpha reductase (BVR-A) and biliverdin-IX beta reductase (BVR-B), they do show weak immunological cross-reactivity. Both enzymes bind to 2',5'-ADP-Sepharose. PMID:8687377

  14. A common mutation A1298C in human methylenetetrahydrofolate reductase gene: association with plasma total homocysteine and folate concentrations.

    Science.gov (United States)

    Friedman, G; Goldschmidt, N; Friedlander, Y; Ben-Yehuda, A; Selhub, J; Babaey, S; Mendel, M; Kidron, M; Bar-On, H

    1999-09-01

    Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Previous studies revealed that a common mutation in MTHFR gene C677T is related to hyperhomocysteinemia and occlusive vascular pathology. In the current study, we determined the prevalence of a newly described mutation in the human MTHFR gene A1298C, and the already known C677T mutation, and related them to plasma total homocysteine and folate concentrations. We studied 377 Jewish subjects, including 190 men and 186 women aged 56.8 +/- 13 y (range 32-95 y). The frequency of the homozygotes for the A1298C and the C677T MTHFR mutations was common in the Jewish Israeli population (0.34 and 0.37, respectively). Subjects homozygous (TT) for the C677T mutation had significantly greater plasma total homocysteine concentrations (P A1298C mutation did not have elevated plasma total homocysteine concentrations. Our study indicated that subjects with the 677CC/1298CC genotype had significantly lower concentrations (P A1298C and the C677T) was associated with established cardiovascular risk factors such as hypertension, elevated total cholesterol or body mass index.

  15. Ribonucleotide reductase inhibitors hydroxyurea, didox, and trimidox inhibit human cytomegalovirus replication in vitro and synergize with ganciclovir.

    Science.gov (United States)

    Bhave, Sukhada; Elford, Howard; McVoy, Michael A

    2013-10-01

    Ganciclovir (GCV) is a deoxyguanosine analog that is effective in inhibiting human cytomegalovirus (HCMV) replication. In infected cells GCV is converted to GCV-triphosphate which competes with dGTP for incorporation into the growing DNA strand by the viral DNA polymerase. Incorporated GCV promotes chain termination as it is an inefficient substrate for elongation. Because viral DNA synthesis also relies on cellular ribonucleotide reductase (RR) to synthesize deoxynucleotides, RR inhibitors are predicted to inhibit HCMV replication. Moreover, as dGTP competes with GCV-triphosphate for incorporation, RR inhibitors may also synergize with GCV by reducing intracellular dGTP levels and there by promoting increased GCV-triphosphate utilization by DNA polymerase. To investigate potential of RR inhibitors as anti-HCMV agents both alone and in combination with GCV, HCMV-inhibitory activities of three RR inhibitors, hydroxyurea, didox, and trimidox, were determined. In both spread inhibition and yield reduction assays RR inhibitors had modest anti-HCMV activity with 50% inhibitory concentrations ranging from 36±1.7 to 221±52μM. However, all three showed significant synergy with GCV at concentrations below their 50% inhibitory and 50% toxic concentrations. These results suggest that combining GCV with relatively low doses of RR inhibitors could significantly potentiate the anti-HCMV activity of GCV in vivo and could improve clinical response to therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Induction of Thioredoxin Reductase 1 by Korean Red Ginseng Water Extract Regulates Cytoprotective Effects on Human Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Hye Rim Park

    2015-01-01

    Full Text Available Korean Red Ginseng is a popular herbal medicine and is widely used in many food products. KRG has biological benefits related to vascular diseases including diabetes, hypertension, atherosclerosis, and other cardiac diseases and KRG has antioxidant and anti-hyperlipidemic actions. KRG decreases the level of oxidative stress and suppresses proinflammatory cytokines and cell adhesion molecules, thus protecting endothelial dysfunction. Mammalian Thioredoxin reductase 1 is an NADPH-dependent selenoprotein, essential for antioxidant defense and DNA synthesis and repair, that regulates the redox system by modulating redox-sensitive transcription factors and thiol-containing proteins. Here, we show that KRG water extract increases the expression of TrxR1 in human umbilical vein endothelial cells via the p38 and PKC-δ signaling pathways. The induction of TrxR1 expression by KRG was confirmed by Western blot analysis and reverse transcription polymerase chain reaction. However, the increase in TrxR1 expression was abolished by specific silencing of the p38 and PKC-δ genes. In addition, we demonstrated that auranofin, a TrxR1 inhibitor, weakens the protective effect of KRG against H2O2-induced cell death as measured by the terminal transferase dUTP nick end labeling assay. These results suggest that KRG may have protective effects in vascular diseases by upregulating TrxR1 in endothelial cells, thereby inhibiting the generation of reactive oxygen species and cell death.

  17. Characterization of human short chain dehydrogenase/reductase SDR16C family members related to retinol dehydrogenase 10.

    Science.gov (United States)

    Adams, Mark K; Lee, Seung-Ah; Belyaeva, Olga V; Wu, Lizhi; Kedishvili, Natalia Y

    2017-10-01

    All-trans-retinoic acid (RA) is a bioactive derivative of vitamin A that serves as an activating ligand for nuclear transcription factors, retinoic acid receptors. RA biosynthesis is initiated by the enzymes that oxidize retinol to retinaldehyde. It is well established that retinol dehydrogenase 10 (RDH10, SDR16C4), which belongs to the 16C family of the short chain dehydrogenase/reductase (SDR) superfamily of proteins, is the major enzyme responsible for the oxidation of retinol to retinaldehyde for RA biosynthesis during embryogenesis. However, several lines of evidence point towards the existence of additional retinol dehydrogenases that contribute to RA biosynthesis in vivo. In close proximity to RDH10 gene on human chromosome 8 are located two genes that are phylogenetically related to RDH10. The predicted protein products of these genes, retinol dehydrogenase epidermal 2 (RDHE2, SDR16C5) and retinol dehydrogenase epidermal 2-similar (RDHE2S, SDR16C6), share 59% and 56% sequence similarity with RDH10, respectively. Previously, we showed that the single ortholog of the human RDHE2 and RDHE2S in frogs, Xenopus laevis rdhe2, oxidizes retinol to retinaldehyde and is essential for frog embryonic development. In this study, we explored the potential of each of the two human proteins to contribute to RA biosynthesis. The results of this study demonstrate that human RDHE2 exhibits a relatively low but reproducible activity when expressed in either HepG2 or HEK293 cells. Expression of the native RDHE2 is downregulated in the presence of elevated levels of RA. On the other hand, the protein encoded by the human RDHE2S gene is unstable when expressed in HEK293 cells. RDHE2S protein produced in Sf9 cells is stable but has no detectable catalytic activity towards retinol. We conclude that the human RDHE2S does not contribute to RA biosynthesis, whereas the low-activity RA-sensitive human RDHE2 may have a role in adjusting the cellular levels of RA in accord with

  18. Activation of human biliverdin-IXα reductase by urea: generation of kinetically distinct forms during the unfolding pathway.

    Science.gov (United States)

    Franklin, Edward; Mantle, Timothy; Dunne, Aisling

    2013-12-01

    Activation of enzymes by low concentrations of denaturants has been reported for a limited number of enzymes including lipocalin-type prostaglandin D synthase (L-PGDS) and adenylate kinase. During unfolding studies on human biliverdin-IXα reductase it was discovered that the enzyme is activated at low concentrations of urea. Under standard assay conditions the native enzyme displays pronounced substrate inhibition with biliverdin as variable substrate; however in the presence of 3M urea, the substrate inhibition is abolished and the enzyme exhibits Michaelian kinetics. When the initial rate kinetics with NADPH as variable substrate are conducted in 3M urea, the Vmax is increased 11-fold to 1.8μmol/min/mg and the apparent Km for biliverdin increases from 1 to 3μM. We report the existence of two kinetically distinct folded intermediates between the native and unfolded forms. When the period of incubation with urea was varied prior to measuring enzyme activity, the apparent Vmax was shown to decay to half that seen at zero time with a half life of 5.8minutes, while the apparent Km for NADPH remains constant at approximately 5μM. With NADH as cofactor the half life of the activated (A) form was 2.9minutes, and this form decays in 3M urea to a less active (LA) form. The apparent Km for NADH increases from 0.33mM to 2mM for the A and LA forms. These kinetically distinct species are reminiscent of the activity-enhanced and inactive forms of L-PGDS observed in the presence of urea and guanidine hydrochloride. © 2013.

  19. Structural role of serine 127 in the NADH-binding site of human NADH-cytochrome b5 reductase.

    Science.gov (United States)

    Yubisui, T; Shirabe, K; Takeshita, M; Kobayashi, Y; Fukumaki, Y; Sakaki, Y; Takano, T

    1991-01-05

    Serine 127 of human NADH-cytochrome b5 reductase was replaced by proline and alanine by site-directed mutagenesis. The former mutation has been found in the genes of patients with hereditary deficiency of the enzyme. Both the mutant enzymes (Ser-127----Pro mutant and Ser-127----Ala mutant) were overproduced in Escherichia coli and purified to homogeneity. The two purified mutant enzymes showed indistinguishable spectral properties which differed from those of the wild-type enzyme. The mutant enzymes showed higher molecular extinction coefficients at 462 nm than that of the wild-type enzyme. Quenching of FAD fluorescence in these mutant enzymes was significantly less than that in the wild-type enzyme. Furthermore, circular dichroism spectra of the mutant enzymes were different, in both the visible and ultraviolet regions, from that of the wild-type enzyme. The spectra of the mutant enzymes in the visible region were restored to almost the same spectrum as the wild type upon reduction with NADH. Ser-127----Pro mutant and Ser-127----Ala mutant showed very low Kcat/Km (NADH) values (5 x 10(7) and 3.5 x 10(7) s-1 M-1, respectively) with cytochrome b5 as an electron acceptor, than that of the wild-type enzyme (Kcat/Km (NADH) = 179 x 10(7) s-1 M-1), while the Kcat/Km (cytochrome b5) value for each enzyme was similar. The mutant enzymes were less thermostable than the wild-type enzyme. These results indicate that serine 127 plays an important role to maintain the structure of the NADH-binding site in the enzyme.

  20. Validation of protein carbonyl measurement

    DEFF Research Database (Denmark)

    Augustyniak, Edyta; Adam, Aisha; Wojdyla, Katarzyna

    2015-01-01

    Protein carbonyls are widely analysed as a measure of protein oxidation. Several different methods exist for their determination. A previous study had described orders of magnitude variance that existed when protein carbonyls were analysed in a single laboratory by ELISA using different commercial...... kits. We have further explored the potential causes of variance in carbonyl analysis in a ring study. A soluble protein fraction was prepared from rat liver and exposed to 0, 5 and 15min of UV irradiation. Lyophilised preparations were distributed to six different laboratories that routinely undertook...... and control liver proteins, only seven were common in all three liver preparations. Lysine and arginine residues modified by carbonyls are likely to be resistant to tryptic proteolysis. Use of a cocktail of proteases may increase the recovery of oxidised peptides. In conclusion, standardisation is critical...

  1. Stereospecific reduction of 5β-reduced steroids by human ketosteroid reductases of the AKR (aldo-keto reductase) superfamily: role of AKR1C1-AKR1C4 in the metabolism of testosterone and progesterone via the 5β-reductase pathway.

    Science.gov (United States)

    Jin, Yi; Mesaros, A Clementina; Blair, Ian A; Penning, Trevor M

    2011-07-01

    Active sex hormones such as testosterone and progesterone are metabolized to tetrahydrosteroids in the liver to terminate hormone action. One main metabolic pathway, the 5β-pathway, involves 5β-steroid reductase (AKR1D1, where AKR refers to the aldo-keto reductase superfamily), which catalyses the reduction of the 4-ene structure, and ketosteroid reductases (AKR1C1-AKR1C4), which catalyse the subsequent reduction of the 3-oxo group. The activities of the four human AKR1C enzymes on 5β-dihydrotestosterone, 5β-pregnane-3,20-dione and 20α-hydroxy-5β-pregnan-3-one, the intermediate 5β-dihydrosteroids on the 5β-pathway of testosterone and progesterone metabolism, were investigated. Product characterization by liquid chromatography-MS revealed that the reduction of the 3-oxo group of the three steroids predominantly favoured the formation of the corresponding 3α-hydroxy steroids. The stereochemistry was explained by molecular docking. Kinetic properties of the enzymes identified AKR1C4 as the major enzyme responsible for the hepatic formation of 5β-tetrahydrosteroid of testosterone, but indicated differential routes and roles of human AKR1C for the hepatic formation of 5β-tetrahydrosteroids of progesterone. Comparison of the kinetics of the AKR1C1-AKR1C4-catalysed reactions with those of AKR1D1 suggested that the three intermediate 5β-dihydrosteroids derived from testosterone and progesterone are unlikely to accumulate in liver, and that the identities and levels of 5β-reduced metabolites formed in peripheral tissues will be governed by the local expression of AKR1D1 and AKR1C1-AKR1C3.

  2. The structure of the leukemia drug imatinib bound to human quinone reductase 2 (NQO2

    Directory of Open Access Journals (Sweden)

    Winger Jonathan A

    2009-02-01

    Full Text Available Abstract Background Imatinib represents the first in a class of drugs targeted against chronic myelogenous leukemia to enter the clinic, showing excellent efficacy and specificity for Abl, Kit, and PDGFR kinases. Recent screens carried out to find off-target proteins that bind to imatinib identified the oxidoreductase NQO2, a flavoprotein that is phosphorylated in a chronic myelogenous leukemia cell line. Results We examined the inhibition of NQO2 activity by the Abl kinase inhibitors imatinib, nilotinib, and dasatinib, and obtained IC50 values of 80 nM, 380 nM, and >100 μM, respectively. Using electronic absorption spectroscopy, we show that imatinib binding results in a perturbation of the protein environment around the flavin prosthetic group in NQO2. We have determined the crystal structure of the complex of imatinib with human NQO2 at 1.75 Å resolution, which reveals that imatinib binds in the enzyme active site, adjacent to the flavin isoalloxazine ring. We find that phosphorylation of NQO2 has little effect on enzyme activity and is therefore likely to regulate other aspects of NQO2 function. Conclusion The structure of the imatinib-NQO2 complex demonstrates that imatinib inhibits NQO2 activity by competing with substrate for the active site. The overall conformation of imatinib when bound to NQO2 resembles the folded conformation observed in some kinase complexes. Interactions made by imatinib with residues at the rim of the active site provide an explanation for the binding selectivity of NQO2 for imatinib, nilotinib, and dasatinib. These interactions also provide a rationale for the lack of inhibition of the related oxidoreductase NQO1 by these compounds. Taken together, these studies provide insight into the mechanism of NQO2 inhibition by imatinib, with potential implications for drug design and treatment of chronic myelogenous leukemia in patients.

  3. Function of human mitochondrial 2,4-dienoyl-CoA reductase and rat monofunctional Delta3-Delta2-enoyl-CoA isomerase in beta-oxidation of unsaturated fatty acids.

    OpenAIRE

    Gurvitz, A.; Wabnegger, L; Yagi, A I; Binder, M.; Hartig, A; Ruis, H; B. Hamilton; Dawes, I W; Hiltunen, J K; Rottensteiner, H.

    1999-01-01

    Human 2,4-dienoyl-CoA reductase (2,4-reductase; DECR) and rat monofunctional Delta(3)-Delta(2)-enoyl-CoA isomerase (rat 3, 2-isomerase; ECI) are thought to be mitochondrial auxiliary enzymes involved in the beta-oxidation of unsaturated fatty acids. However, their function during this process has not been demonstrated. Although they lack obvious peroxisomal targeting signals (PTSs), both proteins have been suggested previously to also occur in the mammalian peroxisomal compartment. The putati...

  4. Imaging of dihydrofolate reductase fusion gene expression in xenografts of human liver metastases of colorectal cancer in living rats

    Energy Technology Data Exchange (ETDEWEB)

    Mayer-Kuckuk, Philipp; Bertino, Joseph R.; Banerjee, Debabrata [Molecular Pharmacology and Therapeutics Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); The Cancer Institute of New Jersey, Robert Wood Johnson Medical School/UMDNJ, 195 Little Albany Street, NJ 08903, New Brunswick (United States); Doubrovin, Mikhail; Blasberg, Ronald; Tjuvajev, Juri Gelovani [Department of Neurooncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Gusani, Niraj J.; Fong, Yuman [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Gade, Terence; Koutcher, Jason A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Balatoni, Julius; Finn, Ronald [Radiochemistry/Cyclotron Core Facility, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Akhurst, Tim; Larson, Steven [Nuclear Medicine Service, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

    2003-09-01

    Radionuclide imaging has been demonstrated to be feasible to monitor transgene expression in vivo. We hypothesized that a potential application of this technique is to non-invasively detect in deep tissue, such as cancer cells metastatic to the liver, a specific molecular response following systemic drug treatment. Utilizing human colon adenocarcinoma cells derived from a patient's liver lesion we first developed a nude rat xenograft model for colorectal cancer metastatic to the liver. Expression of a dihydrofolate reductase-herpes simplex virus 1 thymidine kinase fusion (DHFR-HSV1 TK) transgene in the hepatic tumors was monitored in individual animals using the tracer [{sup 124}I]2'-fluoro-2'-deoxy-5-iodouracil-{beta}-d-arabinofuranoside (FIAU) and a small animal micro positron emission tomograph (microPET), while groups of rats were imaged using the tracer [{sup 131}I]FIAU and a clinical gamma camera. Growth of the human metastatic colorectal cancer cells in the rat liver was detected using magnetic resonance imaging and confirmed by surgical inspection. Single as well as multiple lesions of different sizes and sites were observed in the liver of the animals. Next, using a subset of rats bearing hepatic tumors, which were retrovirally bulk transduced to express the DHFR-HSV1 TK transgene, we imaged the fusion protein expression in the hepatic tumor of living rats using the tracer [{sup 124}I]FIAU and a microPET. The observed deep tissue signals were highly specific for the tumors expressing the DHFR-HSV1 TK fusion protein compared with parental untransduced tumors and other tissues as determined by gamma counting of tissue samples. A subsequent study used the tracer [{sup 131}I]FIAU and a gamma camera to monitor two groups of transduced hepatic tumor-bearing rats. Prior to imaging, one group was treated with trimetrexate to exploit DHFR-mediated upregulation of the fusion gene product. Imaging in the living animal as well as subsequent gamma

  5. The role of 5α-reductase type 1 associated with intratumoral dihydrotestosterone concentrations in human endometrial carcinoma.

    Science.gov (United States)

    Tanaka, Sota; Miki, Yasuhiro; Hashimoto, Chiaki; Takagi, Kiyoshi; Doe, Zhulanqiqige; Li, Bin; Yaegashi, Nobuo; Suzuki, Takashi; Ito, Kiyoshi

    2015-02-05

    Endometrial carcinoma, especially endometrioid endometrial adenocarcinoma, is an estrogen-dependent tumor that is similar to breast cancer. Androgen is closely associated with other steroid hormones, but its correlation with endometrioid endometrial adenocarcinoma remains largely unclear. We previously demonstrated the expression of the androgen receptor, 5α-reductase type 1, and 5α-reductase type 2 in endometrioid endometrial adenocarcinoma tissue, but androgen action and its correlation with prognosis are unknown. In this study, we measured the tissue and serum concentrations of androgen and performed immunohistochemical analyses of androgen-associated factors in 41 patients. In 86 additional patients, we performed the same immunohistochemical analyses to identify correlations associated with prognosis. We found that 5α-reductase type 1 was associated with intratumoral dihydrotestosterone concentrations, and it was an independent prognostic factor in endometrioid endometrial adenocarcinoma. The poor prognosis of patients negative for both androgen receptor and 5α-reductase type 1 suggests that androgens have inhibitory effects on tumor growth. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Carbonyl species characteristics during the evaporation of essential oils

    Science.gov (United States)

    Chiang, Hsiu-Mei; Chiu, Hua-Hsien; Lai, Yen-Ming; Chen, Ching-Yen; Chiang, Hung-Lung

    2010-06-01

    Carbonyls emitted from essential oils can affect the air quality when they are used in indoors, especially under poor ventilation conditions. Lavender, lemon, rose, rosemary, and tea tree oils were selected as typical and popular essential oils to investigate in terms of composition, thermal characteristics and fifteen carbonyl constituents. Based on thermogravimetric (TG) analysis, the activation energy was 7.6-8.3 kcal mol -1, the reaction order was in the range of 0.6-0.7 and the frequency factor was 360-2838 min -1. Formaldehyde, acetaldehyde, acetone, and propionaldehyde were the dominant carbonyl compounds, and their concentrations were 0.034-0.170 ppm. The emission factors of carbonyl compounds were 2.10-3.70 mg g -1, and acetone, propionaldehyde, acetaldehyde, and formaldehyde accounted for a high portion of the emission factor of carbonyl compounds in essential oil exhaust. Some unhealthy carbonyl species such as formaldehyde and valeraldehyde, were measured at low-temperature during the vaporization of essential oils, indicating a potential effect on indoor air quality and human health.

  7. Lack of functional and expression homology between human and mouse aldo-keto reductase 1C enzymes: implications for modelling human cancers

    Directory of Open Access Journals (Sweden)

    Schrewe Heinrich

    2009-12-01

    Full Text Available Abstract Background Over recent years, enzymes of the aldo-keto reductase (AKR 1C subfamily have been implicated in the progression of prostate, breast, endometrial and leukemic cancers. This is due to the ability of AKR1C enzymes to modify androgens, estrogens, progesterone and prostaglandins (PGs in a tissue-specific manner, regulating the activity of nuclear receptors and other downstream effects. Evidence supporting a role for AKR1C enzymes in cancer derives mostly from studies with isolated primary cells from patients or immortalized cell lines. Mice are ideal organisms for in vivo studies, using knock-out or over-expression strains. However, the functional conservation of AKR1C enzymes between human and mice has yet to be described. Results In this study, we have characterized and compared the four human (AKR1C1,-1C2, -1C3 and -1C4 and the eight murine (AKR1C6, -1C12, -1C13, -1C14, -1C18, -1C19, -1C20 and -1C21 isoforms in their phylogeny, substrate preference and tissue distribution. We have found divergent evolution between human and murine AKR1C enzymes that was reflected by differing substrate preference. Murine enzymes did not perform the 11β-ketoreduction of prostaglandin (PG D2, an activity specific to human AKR1C3 and important in promoting leukemic cell survival. Instead, murine AKR1C6 was able to perform the 9-ketoreduction of PGE2, an activity absent amongst human isoforms. Nevertheless, reduction of the key steroids androstenedione, 5α-dihydrotestosterone, progesterone and estrone was found in murine isoforms. However, unlike humans, no AKR1C isoforms were detected in murine prostate, testes, uterus and haemopoietic progenitors. Conclusions This study exposes significant lack of phylogenetic and functional homology between human and murine AKR1C enzymes. Therefore, we conclude that mice are not suitable to model the role of AKR1C in human cancers and leukemia.

  8. Dihydrofolate-Reductase Mutations in Plasmodium knowlesi Appear Unrelated to Selective Drug Pressure from Putative Human-To-Human Transmission in Sabah, Malaysia.

    Directory of Open Access Journals (Sweden)

    Matthew J Grigg

    Full Text Available Malaria caused by zoonotic Plasmodium knowlesi is an emerging threat in Eastern Malaysia. Despite demonstrated vector competency, it is unknown whether human-to-human (H-H transmission is occurring naturally. We sought evidence of drug selection pressure from the antimalarial sulfadoxine-pyrimethamine (SP as a potential marker of H-H transmission.The P. knowlesi dihdyrofolate-reductase (pkdhfr gene was sequenced from 449 P. knowlesi malaria cases from Sabah (Malaysian Borneo and genotypes evaluated for association with clinical and epidemiological factors. Homology modelling using the pvdhfr template was used to assess the effect of pkdhfr mutations on the pyrimethamine binding pocket.Fourteen non-synonymous mutations were detected, with the most common being at codon T91P (10.2% and R34L (10.0%, resulting in 21 different genotypes, including the wild-type, 14 single mutants, and six double mutants. One third of the P. knowlesi infections were with pkdhfr mutants; 145 (32% patients had single mutants and 14 (3% had double-mutants. In contrast, among the 47 P. falciparum isolates sequenced, three pfdhfr genotypes were found, with the double mutant 108N+59R being fixed and the triple mutants 108N+59R+51I and 108N+59R+164L occurring with frequencies of 4% and 8%, respectively. Two non-random spatio-temporal clusters were identified with pkdhfr genotypes. There was no association between pkdhfr mutations and hyperparasitaemia or malaria severity, both hypothesized to be indicators of H-H transmission. The orthologous loci associated with resistance in P. falciparum were not mutated in pkdhfr. Subsequent homology modelling of pkdhfr revealed gene loci 13, 53, 120, and 173 as being critical for pyrimethamine binding, however, there were no mutations at these sites among the 449 P. knowlesi isolates.Although moderate diversity was observed in pkdhfr in Sabah, there was no evidence this reflected selective antifolate drug pressure in humans.

  9. Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism ...

    African Journals Online (AJOL)

    Polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene are associated with abortion, early embryo loss and recurrent spontaneous abortion in human. However, information on the association between MTHFR polymorphism and cow abortion is scarce. In the present study, the effects of MTHFR ...

  10. Short-chain dehydrogenase/reductase (SDR) relationships: a large family with eight clusters common to human, animal, and plant genomes.

    Science.gov (United States)

    Kallberg, Yvonne; Oppermann, Udo; Jörnvall, Hans; Persson, Bengt

    2002-03-01

    The progress in genome characterizations has opened new routes for studying enzyme families. The availability of the human genome enabled us to delineate the large family of short-chain dehydrogenase/reductase (SDR) members. Although the human genome releases are not yet final, we have already found 63 members. We have also compared these SDR forms with those of three model organisms: Caenorhabditis elegans, Drosophila melanogaster, and Arabidopsis thaliana. We detect eight SDR ortholog clusters in a cross-genome comparison. Four of these clusters represent extended SDR forms, a subgroup found in all life forms. The other four are classical SDRs with activities involved in cellular differentiation and signalling. We also find 18 SDR genes that are present only in the human genome of the four genomes studied, reflecting enzyme forms specific to mammals. Close to half of these gene products represent steroid dehydrogenases, emphasizing the regulatory importance of these enzymes.

  11. Determination of Carbonyl Compounds in Exhaled Cigarette Smoke

    Directory of Open Access Journals (Sweden)

    Moldoveanu S

    2014-12-01

    Full Text Available This paper presents the findings on a quantitative evaluation of carbonyl levels in exhaled cigarette smoke from human subjects. The cigarettes evaluated include products with 5.0 mg ‘tar’, 10.6 mg ‘tar’ and 16.2 mg ‘tar’, where ‘tar’ is defined as the weight of total wet particulate matter (TPM minus the weight of nicotine and water, and the cigarettes are smoked following U.S. Federal Trade Commission (FTC recommendations. The measured levels of carbonyls in the exhaled smoke were compared with calculated yields of carbonyls in the inhaled smoke and a retention efficiency was obtained. The number of human subjects included a total of ten smokers for the 10.6 mg ‘tar’, five for the 16.2 mg ‘tar’, and five for the 5.0 mg ‘tar’ product, each subject smoking three cigarettes. The analyzed carbonyl compounds included several aldehydes (formaldehyde, acetaldehyde, acrolein, propionaldehyde, crotonaldehyde and n-butyraldehyde, and two ketones (acetone and 2-butanone. The smoke collection from the human subjects was vacuum assisted. Exhaled smoke was collected on Cambridge pads pretreated with a solution of dinitrophenylhydrazine (DNPH followed by high performance liquid chromatography (HPLC analysis of the dinitrophenylhydrazones of the carbonyl compounds. The cigarette butts from the smokers were collected and analyzed for nicotine. The nicotine levels for the cigarette butts from the smokers were used to calculate the level of carbonyls in the inhaled smoke, based on calibration curves. These were generated separately by analyzing the carbonyls in smoke and the nicotine in the cigarette butts obtained by machine smoking under different puffing regimes. The comparison of the level of carbonyl compounds in exhaled smoke with that from the inhaled smoke showed high retention of all the carbonyls. The retention of aldehydes was above 95% for all three different ‘tar’ levels cigarettes. The ketones were retained with a

  12. Carbonyl compounds in gas and particle phases of mainstream cigarette smoke

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Xiaobing, E-mail: pangxbyuanj@gmail.com [Department of Chemistry, University of York, Heslington, York, YO10 5DD (United Kingdom); Lewis, Alastair C., E-mail: ally.lewis@york.ac.uk [National Centre for Atmospheric Science, University of York, Heslington, York, YO10 5DD (United Kingdom)

    2011-11-01

    Carbonyl compounds (carbonyls) are important constituents of cigarette smoke and some are toxic and may be carcinogenic or mutagenic to humans. In this study carbonyl emissions in the gas and particle phases of mainstream cigarette smoke were assessed by GC-MS with pentafluorophenyl hydrazine (PFPH) derivatization. Seven brands of cigarettes and one brand of cigar common in the UK market and having differing nicotine, tar and carbon monoxide yields were investigated. Sixteen carbonyl components were identified in gaseous emissions and twenty in the particle phase. In the gaseous emissions, acetaldehyde presented as the predominant species, followed by formaldehyde, 2-propenal, and pentanal. In the particulate emissions, 1-hydroxy-2-propanone was the most abundant followed by formaldehyde, benzaldehyde, and 2,5-dimethylbenzaldehyde. Significant differences were found in carbonyl emissions among the brands of cigarettes. The gaseous carbonyl emissions varied in the range of 216-405 {mu}g cigarette{sup -1} ({mu}g cig{sup -1}) and the particulate carbonyl emissions varied in the range of 23-127 {mu}g cig{sup -1}. Positive correlations were found between the total emission of carbonyls, tar yield and carbon monoxide yield. Similar gas/particle (G/P) partitioning ratios of carbonyls were found among all cigarettes, which implies that G/P partitions of carbonyls in smoke mainly depend on the physical properties of the carbonyls. The gaseous carbonyl emissions were enhanced by 40% to 130% when some of the water, accounting for 8-12% of cigarettes in mass, was removed from the tobacco. Non-filtered cigarettes showed significantly higher carbonyl emissions compared to their filtered equivalents. Carbonyl particulate accounted for 11-19% by mass of total particulate matter from tobacco smoke. The cigar generated 806 {mu}g cig{sup -1} gaseous and 141 {mu}g cig{sup -1} particulate carbonyls, which is 2-4 times greater than the cigarettes. - Highlights: {yields} Carbonyl

  13. Oxidative Stress and Carbonyl Lesions in Ulcerative Colitis and Associated Colorectal Cancer

    Directory of Open Access Journals (Sweden)

    Zhiqi Wang

    2016-01-01

    Full Text Available Oxidative stress has long been known as a pathogenic factor of ulcerative colitis (UC and colitis-associated colorectal cancer (CAC, but the effects of secondary carbonyl lesions receive less emphasis. In inflammatory conditions, reactive oxygen species (ROS, such as superoxide anion free radical (O2∙-, hydrogen peroxide (H2O2, and hydroxyl radical (HO∙, are produced at high levels and accumulated to cause oxidative stress (OS. In oxidative status, accumulated ROS can cause protein dysfunction and DNA damage, leading to gene mutations and cell death. Accumulated ROS could also act as chemical messengers to activate signaling pathways, such as NF-κB and p38 MAPK, to affect cell proliferation, differentiation, and apoptosis. More importantly, electrophilic carbonyl compounds produced by lipid peroxidation may function as secondary pathogenic factors, causing further protein and membrane lesions. This may in turn exaggerate oxidative stress, forming a vicious cycle. Electrophilic carbonyls could also cause DNA mutations and breaks, driving malignant progression of UC. The secondary lesions caused by carbonyl compounds may be exceptionally important in the case of host carbonyl defensive system deficit, such as aldo-keto reductase 1B10 deficiency. This review article updates the current understanding of oxidative stress and carbonyl lesions in the development and progression of UC and CAC.

  14. Aldo-keto Reductase Family 1 B10 as a Novel Target for Breast Cancer Treatment

    Science.gov (United States)

    2010-08-01

    aldo-keto reductase family protein AKR1B10 is highly correlated with smokers ’ non -small cell lung carcinomas. Clin Cancer Res 11: 1776-1785. Gallego...reductase family 1 B10 protein detoxifies dietary and lipid -derived alpha, beta-unsaturated carbonyls at physiological levels . Biochem Biophys Res...AKR1B10 expression in breast cancer, define the role of AKR1B10 in lipid metabolism, proliferation, and tumorigenicity of breast cancer cells using

  15. Radical carbonylations using a continuous microflow system

    OpenAIRE

    Takahide Fukuyama; Md. Taifur Rahman; Naoya Kamata; Ilhyong Ryu

    2009-01-01

    Summary Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  16. Radical carbonylations using a continuous microflow system

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2009-07-01

    Full Text Available Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  17. Human dehydrogenase/reductase (SDR family) member 8 (DHRS8): a description and evaluation of its biochemical properties.

    Science.gov (United States)

    Lundová, Tereza; Štambergová, Hana; Zemanová, Lucie; Svobodová, Markéta; Havránková, Jana; Šafr, Miroslav; Wsól, Vladimír

    2016-01-01

    Dehydrogenase/reductase (SDR family) member 8 (DHRS8, SDR16C2) belongs to the short-chain dehydrogenase/reductase (SDR) superfamily, one of the largest enzyme groups. In addition to the well-known members which participate in the metabolism of important eobiotics and xenobiotics, this superfamily contains many poorly characterized proteins. DHRS8 is a member of the Multisubstrate NADP(H)-dependent SDR16C family, which generally contains insufficiently described enzymes. Despite the limited knowledge about DHRS8, preliminary indicators have emerged regarding its significant function in the modulation of steroidal activity, at least in the case of 3α-adiol, lipid metabolism and detoxification. The aim of this study was to describe additional biochemical properties of DHRS8 and to unify knowledge about this enzyme. The DHRS8 was prepared in recombinant form and its membrane topology in the endoplasmic reticulum as an integral protein with cytosolic orientation was demonstrated. The enzyme participates in the NAD(+)-dependent oxidation of steroid hormones as β-estradiol and testosterone in vitro; apparent K m and V max values were 39.86 µM and 0.80 nmol × mg(-1) × min(-1) for β-estradiol and 1207.29 µM and 3.45 nmol × mg(-1) × min(-1) for testosterone. Moreover, synthetic steroids (methyltestosterone and nandrolone) used as anabolics as well as all-trans-retinol were for the first time identified as substrates of DHRS8. This knowledge of its in vitro activity together with a newly described expression pattern at the protein level in tissues involved in steroidogenesis (adrenal gland and testis) and detoxification (liver, lung, kidney and small intestine) could suggest a potential role of DHRS8 in vivo.

  18. Synthesis of 17beta-N-substituted 19-Nor-10-azasteroids as inhibitors of human 5alpha-reductases I and II.

    Science.gov (United States)

    Scarpi, Dina; Occhiato, Ernesto G; Danza, Giovanna; Serio, Mario; Guarna, Antonio

    2002-11-01

    The synthesis of 17beta-[N-(phenyl)methyl/phenyl-amido] substituted 10-azasteroids has been accomplished by either the TiCl4- or TMSOTf-catalysed reaction of carbamates 11 and 12 with Danishefsky's diene. The reaction provided 5alpha-H isomers 3a-5a and 5beta-H isomers 3b-5b depending on the reaction conditions. Both epimers of each compound were tested against human 5alpha-reductase types I and II. Unexpectedly, 5beta-H compounds were found more active than their 5alpha-H counterparts, the best inhibitors being 3b (IC50=279 and 2000 nM toward isoenzyme I and II, respectively) and 5b (IC50=913 and 247 nM toward isoenzymes I and II, respectively).

  19. Lipid Peroxide-Derived Short-Chain Carbonyls Mediate Hydrogen Peroxide-Induced and Salt-Induced Programmed Cell Death in Plants1[OPEN

    Science.gov (United States)

    Biswas, Md. Sanaullah; Mano, Jun’ichi

    2015-01-01

    Lipid peroxide-derived toxic carbonyl compounds (oxylipin carbonyls), produced downstream of reactive oxygen species (ROS), were recently revealed to mediate abiotic stress-induced damage of plants. Here, we investigated how oxylipin carbonyls cause cell death. When tobacco (Nicotiana tabacum) Bright Yellow-2 (BY-2) cells were exposed to hydrogen peroxide, several species of short-chain oxylipin carbonyls [i.e. 4-hydroxy-(E)-2-nonenal and acrolein] accumulated and the cells underwent programmed cell death (PCD), as judged based on DNA fragmentation, an increase in terminal deoxynucleotidyl transferase dUTP nick end labeling-positive nuclei, and cytoplasm retraction. These oxylipin carbonyls caused PCD in BY-2 cells and roots of tobacco and Arabidopsis (Arabidopsis thaliana). To test the possibility that oxylipin carbonyls mediate an oxidative signal to cause PCD, we performed pharmacological and genetic experiments. Carnosine and hydralazine, having distinct chemistry for scavenging carbonyls, significantly suppressed the increase in oxylipin carbonyls and blocked PCD in BY-2 cells and Arabidopsis roots, but they did not affect the levels of ROS and lipid peroxides. A transgenic tobacco line that overproduces 2-alkenal reductase, an Arabidopsis enzyme to detoxify α,β-unsaturated carbonyls, suffered less PCD in root epidermis after hydrogen peroxide or salt treatment than did the wild type, whereas the ROS level increases due to the stress treatments were not different between the lines. From these results, we conclude that oxylipin carbonyls are involved in the PCD process in oxidatively stressed cells. Our comparison of the ability of distinct carbonyls to induce PCD in BY-2 cells revealed that acrolein and 4-hydroxy-(E)-2-nonenal are the most potent carbonyls. The physiological relevance and possible mechanisms of the carbonyl-induced PCD are discussed. PMID:26025050

  20. E2F1 promote the aggressiveness of human colorectal cancer by activating the ribonucleotide reductase small subunit M2

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zejun [Sanmen People' s Hospital of Zhejiang, Sanmen, Zhejiang, 317100 (China); Gong, Chaoju [Department of Pathology and Pathophysiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058 (China); Liu, Hong [Zhejiang Normal University – Jinhua People' s Hospital Joint Center for Biomedical Research, Jinhua, Zhejiang, 321004 (China); Zhang, Xiaomin; Mei, Lingming [Sanmen People' s Hospital of Zhejiang, Sanmen, Zhejiang, 317100 (China); Song, Mintao [Department of Pathophysiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences (CAMS), School of Basic Medicine, Peking Union Medical College (PUMC), Beijing, 100005 (China); Qiu, Lanlan; Luo, Shuchai; Zhu, Zhihua; Zhang, Ronghui; Gu, Hongqian [Sanmen People' s Hospital of Zhejiang, Sanmen, Zhejiang, 317100 (China); Chen, Xiang, E-mail: sychenxiang@126.com [Sanmen People' s Hospital of Zhejiang, Sanmen, Zhejiang, 317100 (China)

    2015-08-21

    As the ribonucleotide reductase small subunit, the high expression of ribonucleotide reductase small subunit M2 (RRM2) induces cancer and contributes to tumor growth and invasion. In several colorectal cancer (CRC) cell lines, we found that the expression levels of RRM2 were closely related to the transcription factor E2F1. Mechanistic studies were conducted to determine the molecular basis. Ectopic overexpression of E2F1 promoted RRM2 transactivation while knockdown of E2F1 reduced the levels of RRM2 mRNA and protein. To further investigate the roles of RRM2 which was activated by E2F1 in CRC, CCK-8 assay and EdU incorporation assay were performed. Overexpression of E2F1 promoted cell proliferation in CRC cells, which was blocked by RRM2 knockdown attenuation. In the migration and invasion tests, overexpression of E2F1 enhanced the migration and invasion of CRC cells which was abrogated by silencing RRM2. Besides, overexpression of RRM2 reversed the effects of E2F1 knockdown partially in CRC cells. Examination of clinical CRC specimens demonstrated that both RRM2 and E2F1 were elevated in most cancer tissues compared to the paired normal tissues. Further analysis showed that the protein expression levels of E2F1 and RRM2 were parallel with each other and positively correlated with lymph node metastasis (LNM), TNM stage and distant metastasis. Consistently, the patients with low E2F1 and RRM2 levels have a better prognosis than those with high levels. Therefore, we suggest that E2F1 can promote CRC proliferation, migration, invasion and metastasis by regulating RRM2 transactivation. Understanding the role of E2F1 in activating RRM2 transcription will help to explain the relationship between E2F1 and RRM2 in CRC and provide a novel predictive marker for diagnosis and prognosis of the disease. - Highlights: • E2F1 promotes RRM2 transactivation in CRC cells. • E2F1 promotes the proliferation of CRC cells by activating RRM2. • E2F1 promotes the migration and

  1. Sex hormones reduce NNK detoxification through inhibition of short-chain dehydrogenases/reductases and aldo-keto reductases in vitro.

    Science.gov (United States)

    Stapelfeld, Claudia; Maser, Edmund

    2017-10-01

    Carbonyl reduction is an important metabolic pathway for endogenous and xenobiotic substances. The tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK, nicotine-derived nitrosamine ketone) is classified as carcinogenic to humans (IARC, Group 1) and considered to play the most important role in tobacco-related lung carcinogenesis. Detoxification of NNK through carbonyl reduction is catalyzed by members of the AKR- and the SDR-superfamilies which include AKR1B10, AKR1C1, AKR1C2, AKR1C4, 11β-HSD1 and CBR1. Because some reductases are also involved in steroid metabolism, five different hormones were tested for their inhibitory effect on NNK carbonyl reduction. Two of those hormones were estrogens (estradiol and ethinylestradiol), another two hormones belong to the gestagen group (progesterone and drospirenone) and the last tested hormone was an androgen (testosterone). Furthermore, one of the estrogens (ethinylestradiol) and one of the gestagens (drospirenone) are synthetic hormones, used as hormonal contraceptives. Five of six NNK reducing enzymes (AKR1B10, AKR1C1, AKR1C2, AKR1C4 and 11β-HSD1) were significantly inhibited by the tested sex hormones. Only NNK reduction catalyzed by CBR1 was not significantly impaired. In the case of the other five reductases, gestagens had remarkably stronger inhibitory effects at a concentration of 25 μM (progesterone: 66-88% inhibition; drospirenone: 26-87% inhibition) in comparison to estrogens (estradiol: 17-51% inhibition; ethinylestradiol: 14-79% inhibition) and androgens (14-78% inhibition). Moreover, in most cases the synthetic hormones showed a greater ability to inhibit NNK reduction than the physiologic derivatives. These results demonstrate that male and female sex hormones have different inhibitory potentials, thus indicating that there is a varying detoxification capacity of NNK in men and women which could result in a different risk for developing lung cancer. Copyright © 2017 Elsevier B

  2. Bacterial Over-Expression and Purification of the 3'phosphoadenosine 5'phosphosulfate (PAPS Reductase Domain of Human FAD Synthase: Functional Characterization and Homology Modeling

    Directory of Open Access Journals (Sweden)

    Maria Barile

    2012-12-01

    Full Text Available FAD synthase (FADS, EC 2.7.7.2 is a key enzyme in the metabolic pathway that converts riboflavin into the redox cofactor, FAD. Human FADS is organized in two domains: -the 3'phosphoadenosine 5'phosphosulfate (PAPS reductase domain, similar to yeast Fad1p, at the C-terminus, and -the resembling molybdopterin-binding domain at the N-terminus. To understand whether the PAPS reductase domain of hFADS is sufficient to catalyze FAD synthesis, per se, and to investigate the role of the molybdopterin-binding domain, a soluble “truncated” form of hFADS lacking the N-terminal domain (Δ1-328-hFADS has been over-produced and purified to homogeneity as a recombinant His-tagged protein. The recombinant Δ1-328-hFADS binds one mole of FAD product very tightly as the wild-type enzyme. Under turnover conditions, it catalyzes FAD assembly from ATP and FMN and, at a much lower rate, FAD pyrophosphorolytic hydrolysis. The Δ1-328-hFADS enzyme shows a slight, but not significant, change of Km values (0.24 and 6.23 µM for FMN and ATP, respectively and of kcat (4.2 × 10−2 s−1 compared to wild-type protein in the forward direction. These results demonstrate that the molybdopterin-binding domain is not strictly required for catalysis. Its regulatory role is discussed in light of changes in divalent cations sensitivity of the Δ1-328-hFADS versus wild-type protein.

  3. HMG-CoA reductase inhibition aborts functional differentiation and triggers apoptosis in cultured primary human monocytes: a potential mechanism of statin-mediated vasculoprotection

    Directory of Open Access Journals (Sweden)

    Vamvakopoulos Joannis E

    2003-07-01

    Full Text Available Abstract Background Statins effectively lower blood cholesterol and the risk of cardiovascular death. Immunomodulatory actions, independent of their lipid-lowering effect, have also been ascribed to these compounds. Since macrophages participate in several vascular pathologies, we examined the effect of statin treatment on the survival and differentiation of primary human monocytes. Methods Peripheral blood mononuclear cells (PBMCs from healthy individuals were cultured in the presence or absence of mevastatin. Apoptosis was monitored by annexin V / PI staining and flow cytometry. In parallel experiments, cultures were stimulated with LPS in the presence or absence of mevastatin and the release of IL-1β and IL-1Ra was measured by ELISA. Results Among PBMCs, mevastatin-treated monocytes were particularly susceptible to apoptosis, which occurred at doses >1 microM and was already maximal at 5 microM. However, even at the highest mevastatin dose used (10 microM, apoptosis occurred only after 24 h of culture, possibly reflecting a requirement for cell commitment to differentiation. After 72 h of treatment the vast majority (>50% of monocytes were undergoing apoptosis. Stimulation with LPS revealed that mevastatin-treated monocytes retained the high IL-1β output characteristic of undifferentiated cells; conversely, IL-1Ra release was inhibited. Concurrent treatment with mevalonolactone prevented the induction of apoptosis and suppressed both IL-1β and IL-1Ra release in response to LPS, suggesting a rate-limiting role for HMG-CoA reductase in monocyte differentiation. Conclusions Our findings indicate that statins arrest the functional differentiation of monocytes into macrophages and steer these cells into apoptosis, suggesting a novel mechanism for the vasculoprotective properties of HMG-CoA reductase inhibitors.

  4. Structure of Human B12 Trafficking Protein CblD Reveals Molecular Mimicry and Identifies a New Subfamily of Nitro-FMN Reductases.

    Science.gov (United States)

    Yamada, Kazuhiro; Gherasim, Carmen; Banerjee, Ruma; Koutmos, Markos

    2015-12-04

    In mammals, B12 (or cobalamin) is an essential cofactor required by methionine synthase and methylmalonyl-CoA mutase. A complex intracellular pathway supports the assimilation of cobalamin into its active cofactor forms and delivery to its target enzymes. MMADHC (the methylmalonic aciduria and homocystinuria type D protein), commonly referred to as CblD, is a key chaperone involved in intracellular cobalamin trafficking, and mutations in CblD cause methylmalonic aciduria and/or homocystinuria. Herein, we report the first crystal structure of the globular C-terminal domain of human CblD, which is sufficient for its interaction with MMADHC (the methylmalonic aciduria and homocystinuria type C protein), or CblC, and for supporting the cytoplasmic cobalamin trafficking pathway. CblD contains an α+β fold that is structurally reminiscent of the nitro-FMN reductase superfamily. Two of the closest structural relatives of CblD are CblC, a multifunctional enzyme important for cobalamin trafficking, and the activation domain of methionine synthase. CblD, CblC, and the activation domain of methionine synthase share several distinguishing features and, together with two recently described corrinoid-dependent reductive dehalogenases, constitute a new subclass within the nitro-FMN reductase superfamily. We demonstrate that CblD enhances oxidation of cob(II)alamin bound to CblC and that disease-causing mutations in CblD impair the kinetics of this reaction. The striking structural similarity of CblD to CblC, believed to be contiguous in the cobalamin trafficking pathway, suggests the co-option of molecular mimicry as a strategy for achieving its function. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Transition metal catalyzed carbonylation reactions carbonylative activation of C-X bonds

    CERN Document Server

    Beller, Matthias

    2014-01-01

    This book provides students and researchers in organic synthesis with a detailed discussion of carbonylation from the basics through to applications. It discusses the past, present and future of carbonylation reactions.

  6. Escherichia coli MTC, a human NADPH P450 reductase competent mutagenicity tester strain for the expression of human cytochrome P450 isoforms 1A1, 1A2, 2A6, 3A4, or 3A5: catalytic activities and mutagenicity studies.

    NARCIS (Netherlands)

    Kranendonk, M.; Carreira, F.; Theisen, P.; Laires, A.; Fischer, C.W.; Rueff, J.; Estabrook, R.W.; Vermeulen, N.P.E.; Roda, R.

    1999-01-01

    We report here on the genetic engineering of four new Escherichia coli tester bacteria, coexpressing human CYP1A1, CYP2A6, CYP3A4 or CYP3A5 with human NADPH cytochrome P450 reductase (RED) by a biplasmid coexpression system, recently developed to express human CYP1A2 in the tester strain MTC. The

  7. In search for function of two human orphan SDR enzymes: hydroxysteroid dehydrogenase like 2 (HSDL2) and short-chain dehydrogenase/reductase-orphan (SDR-O).

    Science.gov (United States)

    Kowalik, Dorota; Haller, Ferdinand; Adamski, Jerzy; Moeller, Gabriele

    2009-11-01

    The protein superfamily of short-chain dehydrogenases/reductases (SDRs) today comprises over 20,000 members found in pro- and eukaryotes. Despite low amino acid sequence identity (only 15-30%), they share several similar characteristics in conformational structures, the N-terminal cofactor (NAD(P)/NAD(P)H) binding region being the most conserved. The enzymes catalyze oxido-reductive reactions and have a broad spectrum of substrates. Not all recently identified SDRs have been analyzed in detail yet, and we therefore characterized two rudimentarily annotated human SDR candidates: an orphan SDR (SDR-O) and hydroxysteroid dehydrogenase like 2 (HSDL2). We analyzed the amino acid sequence for cofactor preference, performed subcellular localization studies, and a screening for substrates of the enzymes, including steroid hormones and retinoids. None of both tested proteins showed a significant conversion of steroid hormones. However, the peroxisomal localization of human HSDL2 may suggest an involvement in fatty acid metabolism. For SDR-O a weak conversion of retinal into retinol was detectable in the presence of the cofactor NADH.

  8. EM23, a natural sesquiterpene lactone, targets thioredoxin reductase to activate JNK and cell death pathways in human cervical cancer cells.

    Science.gov (United States)

    Shao, Fang-Yuan; Wang, Sheng; Li, Hong-Yu; Chen, Wen-Bo; Wang, Guo-Cai; Ma, Dong-Lei; Wong, Nai Sum; Xiao, Hao; Liu, Qiu-Ying; Zhou, Guang-Xiong; Li, Yao-Lan; Li, Man-Mei; Wang, Yi-Fei; Liu, Zhong

    2016-02-09

    Sesquiterpene lactones (SLs) are the active constituents of a variety of medicinal plants and found to have potential anticancer activities. However, the intracellular molecular targets of SLs and the underlying molecular mechanisms have not been well elucidated. In this study, we observed that EM23, a natural SL, exhibited anti-cancer activity in human cervical cancer cell lines by inducing apoptosis as indicated by caspase 3 activation, XIAP downregulation and mitochondrial dysfunction. Mechanistic studies indicated that EM23-induced apoptosis was mediated by reactive oxygen species (ROS) and the knockdown of thioredoxin (Trx) or thioredoxin reductase (TrxR) resulted in a reduction in apoptosis. EM23 attenuated TrxR activity by alkylation of C-terminal redox-active site Sec498 of TrxR and inhibited the expression levels of Trx/TrxR to facilitate ROS accumulation. Furthermore, inhibition of Trx/TrxR system resulted in the dissociation of ASK1 from Trx and the downstream activation of JNK. Pretreatment with ASK1/JNK inhibitors partially rescued cells from EM23-induced apoptosis. Additionally, EM23 inhibited Akt/mTOR pathway and induced autophagy, which was observed to be proapoptotic and mediated by ROS. Together, these results reveal a potential molecular mechanism for the apoptotic induction observed with SL compound EM23, and emphasize its putative role as a therapeutic agent for human cervical cancer.

  9. EM23, a natural sesquiterpene lactone, targets thioredoxin reductase to activate JNK and cell death pathways in human cervical cancer cells

    Science.gov (United States)

    Chen, Wen-Bo; Wang, Guo-Cai; Ma, Dong-Lei; Wong, Nai Sum; Xiao, Hao; Liu, Qiu-Ying; Zhou, Guang-Xiong; Li, Yao-Lan; Li, Man-Mei; Wang, Yi-Fei; Liu, Zhong

    2016-01-01

    Sesquiterpene lactones (SLs) are the active constituents of a variety of medicinal plants and found to have potential anticancer activities. However, the intracellular molecular targets of SLs and the underlying molecular mechanisms have not been well elucidated. In this study, we observed that EM23, a natural SL, exhibited anti-cancer activity in human cervical cancer cell lines by inducing apoptosis as indicated by caspase 3 activation, XIAP downregulation and mitochondrial dysfunction. Mechanistic studies indicated that EM23-induced apoptosis was mediated by reactive oxygen species (ROS) and the knockdown of thioredoxin (Trx) or thioredoxin reductase (TrxR) resulted in a reduction in apoptosis. EM23 attenuated TrxR activity by alkylation of C-terminal redox-active site Sec498 of TrxR and inhibited the expression levels of Trx/TrxR to facilitate ROS accumulation. Furthermore, inhibition of Trx/TrxR system resulted in the dissociation of ASK1 from Trx and the downstream activation of JNK. Pretreatment with ASK1/JNK inhibitors partially rescued cells from EM23-induced apoptosis. Additionally, EM23 inhibited Akt/mTOR pathway and induced autophagy, which was observed to be proapoptotic and mediated by ROS. Together, these results reveal a potential molecular mechanism for the apoptotic induction observed with SL compound EM23, and emphasize its putative role as a therapeutic agent for human cervical cancer. PMID:26758418

  10. Identification of a fish short-chain dehydrogenase/reductase associated with bone metabolism.

    Science.gov (United States)

    Rosa, Joana; Cox, Cymon J; Leonor Cancela, M; Laizé, Vincent

    2017-12-14

    Although human and mouse genetics have largely contributed to the better understanding of the mechanisms underlying skeletogenesis, much more remains to be uncovered. In this regard alternative and complementary systems have been sought and cell systems capable of in vitro calcification have been developed to study the mechanisms underlying bone formation. In gilthead seabream (Sparus aurata), a gene coding for an unknown protein that is strongly up-regulated during extracellular matrix (ECM) mineralization of a pre-osteoblast cell line was recently identified as a potentially important player in bone formation. In silico analysis of the deduced protein revealed the presence of domains typical of short-chain dehydrogenase/reductases (SDR). Closely related to carbonyl reductase 1, seabream protein belongs to a novel subfamily of SDR proteins with no orthologs in mammals. Analysis of gene expression by qPCR confirmed the strong up-regulation of sdr-like expression during in vitro mineralization but also revealed high expression levels in calcified tissues. A possible role for Sdr-like in osteoblast and bone metabolism was further evidenced through (i) the localization by in situ hybridization of sdr-like transcript in pre-osteoblasts of the operculum and (ii) the regulation of sdr-like gene transcription by Runx2 and retinoic acid receptor, two regulators of osteoblast differentiation and mineralization. Expression data also indicated a role for Sdr-like in gastrointestinal tract homeostasis and during gilthead seabream development at gastrulation and metamorphosis. This study reports a new subfamily of short-chain dehydrogenases/reductases in vertebrates and, for the first time, provides evidence of a role for SDRs in bone metabolism, osteoblast differentiation and/or tissue mineralization. Copyright © 2017. Published by Elsevier B.V.

  11. Different effects of 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors on sterol synthesis in various human cell types

    NARCIS (Netherlands)

    Vliet, A.K. van; Thiel, G.C.F. van; Huisman, R.H.; Moshage, H.; Yap, S.H.; Cohen, L.H.

    1995-01-01

    The three vastatins examined, lovastatin, simvastatin and pravastatin, are equally strong inhibitors of the sterol synthesis in human hepatocytes in culture with IC50-values of 4.1, 8.0 and 2.0 nM, respectively. However, in the human extrahepatic cells: umbilical vascular endothelial cells, retinal

  12. Quinone Reductase 2 Is a Catechol Quinone Reductase

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao (NYMEDCO)

    2008-09-05

    The functions of quinone reductase 2 have eluded researchers for decades even though a genetic polymorphism is associated with various neurological disorders. Employing enzymatic studies using adrenochrome as a substrate, we show that quinone reductase 2 is specific for the reduction of adrenochrome, whereas quinone reductase 1 shows no activity. We also solved the crystal structure of quinone reductase 2 in complexes with dopamine and adrenochrome, two compounds that are structurally related to catecholamine quinones. Detailed structural analyses delineate the mechanism of quinone reductase 2 specificity toward catechol quinones in comparison with quinone reductase 1; a side-chain rotational difference between quinone reductase 1 and quinone reductase 2 of a single residue, phenylalanine 106, determines the specificity of enzymatic activities. These results infer functional differences between two homologous enzymes and indicate that quinone reductase 2 could play important roles in the regulation of catecholamine oxidation processes that may be involved in the etiology of Parkinson disease.

  13. The human biliverdin reductase-based peptide fragments and biliverdin regulate protein kinase Cδ activity: the peptides are inhibitors or substrate for the protein kinase C.

    Science.gov (United States)

    Miralem, Tihomir; Lerner-Marmarosh, Nicole; Gibbs, Peter E M; Tudor, Cicerone; Hagen, Fred K; Maines, Mahin D

    2012-07-13

    PKCδ, a Ser/Thr kinase, promotes cell growth, tumorigenesis, and apoptosis. Human biliverdin reductase (hBVR), a Ser/Thr/Tyr kinase, inhibits apoptosis by reducing biliverdin-IX to antioxidant bilirubin. The enzymes are activated by similar stimuli. Reportedly, hBVR is a kinase-independent activator of PKCδ and is transactivated by the PKC (Gibbs, P. E., Miralem, T., Lerner-Marmarosh, N., Tudor, C., and Maines, M. D. (2012) J. Biol. Chem. 287, 1066-1079). Presently, we examined interactions between the two proteins in the context of regulation of their activities and defining targets of hBVR phosphorylation by PKCδ. LC-MS/MS analysis of PKCδ-activated intact hBVR identified phosphorylated serine positions 21, 33, 230, and 237, corresponding to the hBVR Src homology-2 domain motif (Ser(230) and Ser(237)), flanking the ATP-binding motif (Ser(21)) and in PHPS sequence (Ser(33)) as targets of PKCδ. Ser(21) and Ser(230) were also phosphorylated in hBVR-based peptides. The Ser(230)-containing peptide was a high affinity substrate for PKCδ in vitro and in cells; the relative affinity was PKCδ > PKCβII > PKCζ. Two overlapping peptides spanning this substrate, KRNRYLSF and SFHFKSGSL, were effective inhibitors of PKCδ kinase activity and PKCδ-supported activation of transcription factors Elk1 and NF-κB. Only SFHFKSGSL, in PKCδ-transfected phorbol 12-myristate 13-acetate-stimulated cells, caused membrane blebbing and cell loss. Biliverdin noncovalently inhibited PKCδ, whereas PKCδ potentiated hBVR reductase activity and accelerated the rate of bilirubin formation. This study, together with previous findings, reveals an unexpected regulatory interplay between PKCδ and hBVR in modulating cell death/survival in response to various activating stimuli. In addition, this study has identified novel substrates for and inhibitors of PKCδ. We suggest that hBVR-based technology may have utility to modulate PKCδ-mediated functions in the cell.

  14. Synthesis and activity of 8-substituted benzo[c]quinolizin-3-ones as dual inhibitors of human 5alpha-reductases 1 and 2.

    Science.gov (United States)

    Ferrali, Alessandro; Menchi, Gloria; Occhiato, Ernesto G; Danza, Giovanna; Mancina, Rosa; Serio, Mario; Guarna, Antonio

    2005-01-03

    Some potent dual inhibitors of 5alpha-reductases 1 and 2, based on the benzo[c]quinolizin-3-one structure and with IC(50) values ranging between 93 and 166nM for both isozymes, were found. The presence of the F atom on the ester moiety at the position 8 was crucial. This result can help in the design of other potent, dual inhibitors to be developed as drugs in the treatment of 5alpha-reductase related diseases.

  15. Synergy between sulforaphane and selenium in the up-regulation of thioredoxin reductase and protection against hydrogen peroxide-induced cell death in human hepatocytes.

    Science.gov (United States)

    Li, Dan; Wang, Wei; Shan, Yujuan; Barrera, Lawrence N; Howie, Alexander F; Beckett, Geoffrey J; Wu, Kun; Bao, Yongping

    2012-07-15

    Dietary isothiocyanates and selenium are chemopreventive agents and potent inducers of antioxidant enzymes. It has been previously shown that sulforaphane and selenium have a synergistic effect on the upregulation of thioredoxin reductase-1 (TrxR-1) in human hepatoma HepG2 cells. In this paper, further evidence is presented to show that sulforaphane and selenium synergistically induce TrxR-1 expression in immortalised human hepatocytes. Sulforaphane was found to be more toxic toward hepatocytes than HepG2 cells with IC50=25.1 and 56.4 μM, respectively. Sulforaphane can protect against hydrogen peroxide-induced cell death and this protection was enhanced by co-treatment with selenium. Using siRNA to knock down TrxR-1 or Nrf2, sulforaphane (5 μM)-protected cell viability was reduced from 73% to 46% and 34%, respectively, suggesting that TrxR-1 is an important enzyme in protection against hydrogen peroxide-induced cell death. Sulforaphane-induced TrxR-1 expression was positively associated with significant levels of Nrf2 translocation into the nucleus, but co-treatment with selenium showed no significant increase in Nrf2 translocation. Moreover, MAPK (ERK, JNK and p38) and PI3K/Akt signalling pathways were found to play no significant role in sulforaphane-induced Nrf2 translocation into the nucleus. However, blocking ERK and JNK signalling pathways decreased sulforaphane-induced TrxR-1 mRNA by about 20%; whereas blocking p38 and PI3K/AKT increased TrxR-1 transcription. In summary, a combination of sulforaphane and selenium resulted in a synergistic upregulation of TrxR-1 that contributed to the enhanced protection against free radical-mediated oxidative damage in human hepatocytes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Identifying the emerging human pathogen Scedosporium prolificans by using a species-specific monoclonal antibody that binds to the melanin biosynthetic enzyme tetrahydroxynaphthalene reductase.

    Science.gov (United States)

    Thornton, Christopher R; Ryder, Lauren S; Le Cocq, Kate; Soanes, Darren M

    2015-04-01

    The dematiaceous (melanized) fungus Scedosporium prolificans is an emerging and frequently fatal pathogen of immunocompromised humans and which, along with the closely related fungi Pseudallescheria boydii, Scedosporium apiospermum and S. aurantiacum in the Pseudallescheria-Scedosporium complex, is a contributing aetiology to tsunami lung and central nervous system infections in near-drowning victims who have aspirated water laden with spores. At present, the natural habitat of the fungus is largely unknown, and accurate detection methods are needed to identify environmental reservoirs of infectious propagules. In this study, we report the development of a monoclonal antibody (mAb) (CA4) specific to S. prolificans, which does not cross-react with closely related fungi in the Pseudallescheria-Scedosporium complex or with a wide range of mould and yeast species pathogenic to humans. Using genome sequencing of a soil isolate and targeted gene disruption of the CA4 antigen-encoding gene, we show that mAb CA4 binds to the melanin-biosynthetic enzyme tetrahydroxynaphthalene reductase. Enzyme-deficient mutants produce orange-brown or green-brown spore suspensions compared with the black spore suspension of the wild-type strain. Using mAb CA4 and a mAb (HG12) specific to the related fungi P. boydii, P. apiosperma, S. apiospermum and S. aurantiacum, we demonstrate how the mAbs can be used in combination with a semiselective isolation procedure to track these opportunistic pathogens in environmental samples containing mixed populations of human pathogenic fungi. Specificity of mAb CA4 was confirmed by sequencing of the internally transcribed spacer 1 (ITS1)-5.8S-ITS2 rRNA-encoding regions of fungi isolated from estuarine muds. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Serenoa repens (Permixon) inhibits the 5alpha-reductase activity of human prostate cancer cell lines without interfering with PSA expression.

    Science.gov (United States)

    Habib, Fouad K; Ross, Margaret; Ho, Clement K H; Lyons, Valerie; Chapman, Karen

    2005-03-20

    The phytotherapeutic agent Serenoa repens is an effective dual inhibitor of 5alpha-reductase isoenzyme activity in the prostate. Unlike other 5alpha-reductase inhibitors, Serenoa repens induces its effects without interfering with the cellular capacity to secrete PSA. Here, we focussed on the possible pathways that might differentiate the action of Permixon from that of synthetic 5alpha-reductase inhibitors. We demonstrate that Serenoa repens, unlike other 5alpha-reductase inhibitors, does not inhibit binding between activated AR and the steroid receptor-binding consensus in the promoter region of the PSA gene. This was shown by a combination of techniques: assessment of the effect of Permixon on androgen action in the LNCaP prostate cancer cell line revealed no suppression of AR and maintenance of PSA protein expression at control levels. This was consistent with reporter gene experiments showing that Permixon failed to interfere with AR-mediated transcriptional activation of PSA and that both testosterone and DHT were equally effective at maintaining this activity. Our results demonstrate that despite Serenoa repens effective inhibition of 5alpha-reductase activity in the prostate, it did not suppress PSA secretion. Therefore, we confirm the therapeutic advantage of Serenoa repens over other 5alpha-reductase inhibitors as treatment with the phytotherapeutic agent will permit the continuous use of PSA measurements as a useful biomarker for prostate cancer screening and for evaluating tumour progression. (c) 2004 Wiley-Liss, Inc.

  18. Protein carbonylation sites in bovine raw milk and processed milk products.

    Science.gov (United States)

    Milkovska-Stamenova, Sanja; Mnatsakanyan, Ruzanna; Hoffmann, Ralf

    2017-08-15

    During thermal treatment of milk, proteins are oxidized, which may reduce the nutritional value of milk, abolish protein functions supporting human health, especially important for newborns, and yield potentially harmful products. The side chains of several amino acids can be oxidized to reactive carbonyls, which are often used to monitor oxidative stress in organisms. Here we mapped protein carbonylation sites in raw milk and different brands of pasteurized, ultra high temperature (UHT) treated milk, and infant formulas (IFs) after digesting the precipitated proteins with trypsin. Reactive carbonyls were derivatized with O-(biotinylcarbazoylmethyl)hydroxylamine to enrich the modified peptides by avidin-biotin affinity chromatography and analyze them by nanoRP-UPLC-ESI-MS. Overall, 53 unique carbonylated peptides (37 carbonylation sites, 15 proteins) were identified. Most carbonyls were derived from dicarbonyls (mainly glyoxal). The number of carbonylation sites increased with the harsher processing from raw milk (4) to pasteurized (16) and UHT milk (16) and to IF (24). Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. An innovative strategy for dual inhibitor design and its application in dual inhibition of human thymidylate synthase and dihydrofolate reductase enzymes.

    Directory of Open Access Journals (Sweden)

    Mahreen Arooj

    Full Text Available Due to the diligence of inherent redundancy and robustness in many biological networks and pathways, multitarget inhibitors present a new prospect in the pharmaceutical industry for treatment of complex diseases. Nevertheless, to design multitarget inhibitors is concurrently a great challenge for medicinal chemists. We have developed a novel computational approach by integrating the affinity predictions from structure-based virtual screening with dual ligand-based pharmacophore to discover potential dual inhibitors of human Thymidylate synthase (hTS and human dihydrofolate reductase (hDHFR. These are the key enzymes in folate metabolic pathway that is necessary for the biosynthesis of RNA, DNA, and protein. Their inhibition has found clinical utility as antitumor, antimicrobial, and antiprotozoal agents. A druglike database was utilized to perform dual-target docking studies. Hits identified through docking experiments were mapped over a dual pharmacophore which was developed from experimentally known dual inhibitors of hTS and hDHFR. Pharmacophore mapping procedure helped us in eliminating the compounds which do not possess basic chemical features necessary for dual inhibition. Finally, three structurally diverse hit compounds that showed key interactions at both active sites, mapped well upon the dual pharmacophore, and exhibited lowest binding energies were regarded as possible dual inhibitors of hTS and hDHFR. Furthermore, optimization studies were performed for final dual hit compound and eight optimized dual hits demonstrating excellent binding features at target systems were also regarded as possible dual inhibitors of hTS and hDHFR. In general, the strategy used in the current study could be a promising computational approach and may be generally applicable to other dual target drug designs.

  20. Mode of action of human pharmaceuticals in fish: the effects of the 5-alpha-reductase inhibitor, dutasteride, on reproduction as a case study.

    Science.gov (United States)

    Margiotta-Casaluci, Luigi; Hannah, Robert E; Sumpter, John P

    2013-03-15

    In recent years, a growing number of human pharmaceuticals have been detected in the aquatic environment, generally at low concentrations (sub-ng/L-low μg/L). In most cases, these compounds are characterised by highly specific modes of action, and the evolutionary conservation of drug targets in wildlife species suggests the possibility that pharmaceuticals present in the environment may cause toxicological effects by acting through the same targets as they do in humans. Our research addressed the question of whether or not dutasteride, a pharmaceutical used to treat benign prostatic hyperplasia, may cause adverse effects in a teleost fish, the fathead minnow (Pimephales promelas), by inhibiting the activity of both isoforms of 5α-reductase (5αR), the enzyme that converts testosterone into dihydrotestosterone (DHT). Mammalian pharmacological and toxicological information were used to guide the experimental design and the selection of relevant endpoints, according to the so-called "read-across approach", suggesting that dutasteride may affect male fertility and steroid hormone dynamics. Therefore, a 21-day reproduction study was conducted to determine the effects of dutasteride (10, 32 and 100 μg/L) on fish reproduction. Exposure to dutasteride significantly reduced fecundity of fish and affected several aspects of reproductive endocrine functions in both males and females. However, none of the observed adverse effects occurred at concentrations of exposure lower than 32 μg/L; this, together with the low volume of drug prescribed every year (10.34 kg in the UK in 2011), and the extremely low predicted environmental concentration (0.03 ng/L), suggest that, at present, the potential presence of dutasteride in the environment does not represent a threat to wild fish populations. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Oxidative and reductive metabolism of lipid-peroxidation derived carbonyls.

    Science.gov (United States)

    Singh, Mahavir; Kapoor, Aniruddh; Bhatnagar, Aruni

    2015-06-05

    Extensive research has shown that increased production of reactive oxygen species (ROS) results in tissue injury under a variety of pathological conditions and chronic degenerative diseases. While ROS are highly reactive and can incite significant injury, polyunsaturated lipids in membranes and lipoproteins are their main targets. ROS-triggered lipid-peroxidation reactions generate a range of reactive carbonyl species (RCS), and these RCS spread and amplify ROS-related injury. Several RCS generated in oxidizing lipids, such as 4-hydroxy trans-2-nonenal (HNE), 4-oxo-2-(E)-nonenal (ONE), acrolein, malondialdehyde (MDA) and phospholipid aldehydes have been shown to be produced under conditions of oxidative stress and contribute to tissue injury and dysfunction by depleting glutathione and other reductants leading to the modification of proteins, lipids, and DNA. To prevent tissue injury, these RCS are metabolized by several oxidoreductases, including members of the aldo-keto reductase (AKR) superfamily, aldehyde dehydrogenases (ALDHs), and alcohol dehydrogenases (ADHs). Metabolism via these enzymes results in RCS inactivation and detoxification, although under some conditions, it can also lead to the generation of signaling molecules that trigger adaptive responses. Metabolic transformation and detoxification of RCS by oxidoreductases prevent indiscriminate ROS toxicity, while at the same time, preserving ROS signaling. A better understanding of RCS metabolism by oxidoreductases could lead to the development of novel therapeutic interventions to decrease oxidative injury in several disease states and to enhance resistance to ROS-induced toxicity. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Promiscuity and diversity in 3-ketosteroid reductases

    Science.gov (United States)

    Penning, Trevor M.; Chen, Mo; Jin, Yi

    2014-01-01

    Many steroid hormones contain a Δ4-3-ketosteroid functionality that undergoes sequential reduction by 5α- or 5β- steroid reductases to produce 5α- or 5β-dihydrosteroids; and a subsequent 3-keto-reduction to produce a series of isomeric tetrahydrosteroids. Apart from steroid 5α-reductase all the remaining enzymes involved in the two step reduction process in humans belong to the aldo-keto reductase (AKR) superfamily. The enzymes involved in 3-ketosteroid reduction are AKR1C1–AKR1C4. These enzymes are promiscuous and also catalyze 20-keto- and 17-keto-steroid reduction. Interest in these reactions exist since they regulate steroid hormone metabolism in the liver, and in steroid target tissues, they may regulate steroid hormone receptor occupancy. In addition many of the dihydrosteroids are not biologically inert. The same enzymes are also involved in the metabolism of synthetic steroids e.g., hormone replacement therapeutics, contraceptive agents and inhaled glucocorticoids, and may regulate drug efficacy at their cognate receptors. This article reviews these reactions and the structural basis for substrate diversity in AKR1C1–AKR1C4, ketosteroid reductases. This article is part of a Special Issue entitled ‘Steroid/Sterol signaling’. PMID:25500069

  3. Carbonylation of platelet proteins occurs as consequence of oxidative stress and thrombin activation, and is stimulated by ageing and type 2 diabetes.

    Science.gov (United States)

    Alexandru, Nicoleta; Constantin, Alina; Popov, Doina

    2008-01-01

    In normal ageing, as well as in diabetes mellitus, blood platelets are exposed to increasing amounts of reactive oxygen species. Because occurrence of carbonyl groups is the first step in oxidative damage of proteins, we questioned the formation of carbonylated proteins (i) in vitro: platelets exposed to oxidant hydrogen peroxide (H2O2) and agonist thrombin (in the presence/absence of antioxidants), and (ii) in vivo: during ageing progression, and in type 2 diabetes. Platelets were isolated from the blood of experimental animals (rats and hamsters) and humans (healthy, young and elderly), as well as from type 2 diabetics (matures and elderly). 2,4-Dinitrophenyl derivatization of the amino acid side chains was used to quantify protein carbonyls (spectrophotometry) and to immunodetect carbonylated protein bands (Western blotting). In animal models and humans, H2O2 produced dose-dependent increases in carbonylation of platelet proteins (vs. basal condition). Thrombin activation stimulated protein carbonyl formation in a process quenched by antioxidant catalase, suggesting that carbonylation was induced by the oxidative stress generated by activated platelets. Progression of ageing caused increased carbonylation of platelet proteins (vs. young age); enriched in carbonylated proteins, platelets of elderly subjects were less sensitive to H2O2. Type 2 diabetes additionally enhanced carbonylation of human platelet proteins (vs. the levels at young and elderly healthy subjects). In all experiments, protein carbonyl concentrations were correlated with changes in intensity of 2,4-dinitrophenyl-hydrazine-reactive protein bands on immunoblots. The results suggest that exogenous oxidative stress, thrombin activation, progression of ageing and type 2 diabetes lead to protein carbonyls formation in platelets, and this modification can be attenuated by antioxidant enzymes.

  4. Convenient Reduction of Carbonyl Compounds to their ...

    African Journals Online (AJOL)

    NICO

    Convenient Reduction of Carbonyl Compounds to their. Corresponding Alcohols with NaBH. 4. /(NH. 4. ) 2. C. 2. O. 4. System. Davood Setamdideh* and Sahar Ghahremani. Department of Chemistry, Faculty of Sciences, Mahabad Branch, Islamic Azad University, 59135-443, Iran. Received 6 January 2012, revised 14 ...

  5. Cyclometallated ruthenium (II) carbonyl complexes with 1 ...

    Indian Academy of Sciences (India)

    A facile method for the synthesis of a series of cyclometallated ruthenium(II) carbonyl complexes with 1-pyrenaldehyde 4-R-3-thiosemicarbazones (H2Ln where the two H's represent the dissociable thioamide and pyrenyl protons; R = H, Me and Ph) has been described. The characterization of the complexes having the ...

  6. Millimeter wave spectra of carbonyl cyanide ⋆

    Science.gov (United States)

    Bteich, S.B.; Tercero, B.; Cernicharo, J.; Motiyenko, R.A.; Margulès, L.; Guillemin, J.-C.

    2016-01-01

    Context More than 30 cyanide derivatives of simple organic molecules have been detected in the interstellar medium, but only one dicarbonitrile has been found and that very recently. There is still a lack of high-resolution spectroscopic data particularly for dinitriles derivatives. The carbonyl cyanide molecule is a new and interesting candidate for astrophysical detection. It could be formed by the reaction of CO and CN radicals, or by substitution of the hydrogen atom by a cyano group in cyanoformaldehyde, HC(=O)CN, that has already been detected in the interstellar medium. Aims The available data on the rotational spectrum of carbonyl cyanide is limited in terms of quantum number values and frequency range, and does not allow accurate extrapolation of the spectrum into the millimeter-wave range. To provide a firm basis for astrophysical detection of carbonyl cyanide we studied its millimeter-wave spectrum. Methods The rotational spectrum of carbonyl cyanide was measured in the frequency range 152 - 308 GHz and analyzed using Watson’s A- and S-reduction Hamiltonians. Results The ground and first excited state of v5 vibrational mode were assigned and analyzed. More than 1100 distinct frequency lines of the ground state were fitted to produce an accurate set of rotational and centrifugal distortion constants up to the eighth order. The frequency predictions based on these constants should be accurate enough for astrophysical searches in the frequency range up to 500 GHz and for transition involving energy levels with J ≤ 100 and Ka ≤ 42. Based on the results we searched for interstellar carbonyl cyanide in available observational data without success. Thus, we derived upper limits to its column density in different sources. PMID:27738349

  7. Effect of cooking and drying on carbonyls of oil sardine

    OpenAIRE

    Ammu, K.; Devadasan, K.

    1989-01-01

    Changes in the total as well as major individual carbonyls of oil sardine during steam cooking, oven drying, sun drying and freeze drying are presented. Carbonyls extracted with hexane were converted to their 2:4 dinitro phenyl hydrazone (DNPH) derivatives and were separated into major classes by column chromatography on celite/magnesia. Individual carbonyls were then identified by capillary gas chromatography of the DNPH derivatives. Dehydration and heating increase the carbonyl production f...

  8. Transition-Metal-Catalyzed Carbonylation of Methyl Acetate.

    Science.gov (United States)

    Polichnowski, S. W.

    1986-01-01

    Presents a study of the rhodium-catalyzed, ioding-promoted carbonylation of methyl acetate. This study provides an interesting contrast between the carbonylation of methyl acetate and the carbonylation of methanol when similar rhodium/iodine catalyst systems are used. (JN)

  9. Proteomic identification of carbonylated proteins in F344 rat hippocampus after 1-bromopropane exposure

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhenlie [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan); Department of Toxicology, Guangdong Prevention and Treatment Center for Occupational Diseases, Guangzhou 510‐300 (China); Ichihara, Sahoko [Graduate School of Regional Innovation Studies, Mie University, Tsu 514‐8507 (Japan); Oikawa, Shinji [Department of Environmental and Molecular Medicine, Mie University Graduate School of Medicine, Mie 514‐8507 (Japan); Chang, Jie; Zhang, Lingyi; Subramanian, Kaviarasan; Mohideen, Sahabudeen Sheik [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan); Ichihara, Gaku, E-mail: gak@med.nagoya-u.ac.jp [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Nagoya 466‐8550 (Japan)

    2012-08-15

    1-Bromopropane (1-BP) is neurotoxic in both experimental animals and humans. Previous proteomic analysis of rat hippocampus implicated alteration of protein expression in oxidative stress, suggesting that oxidative stress plays a role in 1-BP-induced neurotoxicity. To understand this role at the protein level, we exposed male F344 rats to 1-BP at 0, 400, or 1000 ppm for 8 h/day for 1 week or 4 weeks by inhalation and quantitated changes in hippocampal protein carbonyl using a protein carbonyl assay, two-dimensional gel electrophoresis (2-DE), immunoblotting, and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-TOF/MS). Hippocampal reactive oxygen species and protein carbonyl were significantly increased, demonstrating 1-BP-associated induction of oxidative stress and protein damage. MALDI-TOF-TOF/MS identified 10 individual proteins with increased carbonyl modification (p < 0.05; fold-change ≥ 1.5). The identified proteins were involved in diverse biological processes including glycolysis, ATP production, tyrosine catabolism, GTP binding, guanine degradation, and neuronal metabolism of dopamine. Hippocampal triosephosphate isomerase (TPI) activity was significantly reduced and negatively correlated with TPI carbonylation (p < 0.001; r = 0.83). Advanced glycation end-product (AGE) levels were significantly elevated both in the hippocampus and plasma, and hippocampal AGEs correlated negatively with TPI activity (p < 0.001; r = 0.71). In conclusion, 1-BP-induced neurotoxicity in the rat hippocampus seems to involve oxidative damage of cellular proteins, decreased TPI activity, and elevated AGEs. -- Highlights: ► 1-BP increases hippocampal ROS levels and hippocampal and plasma protein carbonyls. ► 1-BP increases TPI carbonylation and decreases TPI activity in the hippocampus. ► 1-BP increases hippocampal and plasma AGE levels.

  10. Metabolism of gamma hydroxybutyrate in human hepatoma HepG2 cells by the aldo-keto reductase AKR1A1.

    Science.gov (United States)

    Alzeer, Samar; Ellis, Elizabeth M

    2014-12-01

    Gamma hydroxybutyrate (GHB) is a recreational and date-rape drug, for which the detection following ingestion is hampered by rapid metabolism and its endogenous presence. GHB catabolism occurs mainly by its oxidation to succinic semialdehyde (SSA), which converts to succinate and enters the tricarboxylic acid cycle. A high Km aldehyde reductase has previously been reported to catalyse the NADP-dependent oxidation of GHB at high concentrations. It is assumed that this enzyme is identical to the aldo-keto reductase AKR1A1, but its role in GHB oxidation has not been fully evaluated. In this study, the extent of AKR1A1 in GHB metabolism has been determined in HepG2 cells using RNA-interference technology. The gene encoding AKR1A1 was targeted by siRNA. Results demonstrate a successful knock-down of the AKR1A1 gene with 92% reduction in total mRNA and 93% reduction in protein expression. Demolishing AKR1A1 expression in HepG2 cells leads to significant 82% decrease in NADP-dependent GHB-dehydrogenase activity at high concentration (10mM) of GHB. Moreover, when exposing the cells to 50 μM of GHB for 24h, and measuring intracellular and extracellular GHB levels by GC/MS, a significant two-fold increase was observed on GHB intracellular level in silenced cells. In contrast, measuring SSA-reductase activity in silenced cells indicated that AKR1A1 is not involved in endogenous GHB production. These findings describe a pathway for GHB metabolism in the liver which should be useful in GHB exposure cases, and will enable a better understanding of the enzymes participating in its metabolism at natural and overexposed levels. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. [carbonyl-C-11]desmethyl-WAY-100635 (DWAY) is a potent and selective radioligand for central 5-HT1A receptors in vitro and in vivo

    NARCIS (Netherlands)

    Pike, VW; Halldin, C; McCarron, JA; Lundkvist, C; Hirani, E; Olsson, H; Hume, SP; Karlsson, P; Osman, S; Swahn, CG; Hall, H; Wikstrom, H; Mensonidas, M; Poole, KG; Farde, L

    [carbonyl-C-11]Desmethyl-WAY-100635 (DWAY) is possibly a low-level metabolite appearing in plasma after intravenous administration of [carbonyl(11)C]WAY-100635 to human subjects for positron emission tomographic (PET) imaging of brain 5-HT1A receptors. In this study we set out to assess the ability

  12. The Role of Human Aldo-Keto Reductases (AKRs in the Metabolic Activation and Detoxication of Polycyclic Aromatic Hydrocarbons: Interconversion of PAH-catechols and PAH o-Quinones

    Directory of Open Access Journals (Sweden)

    Li eZhang

    2012-11-01

    Full Text Available Polycyclic aromatic hydrocarbons (PAH are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quiniones. AKRs are also found to be capable of reducing PAH o-quinones to form PAH catechols. The interconversion of o-quinones and catechols results in the redox cycling of PAH o-quinones to give rise to the generation of reactive oxygen species and subsequent oxidative DNA damage. On the other hand, PAH catechols can be intercepted through phase II metabolism by which PAH o-quinones could be detoxified and eliminated. The aim of the present review is to summarize the role of human AKRs in the metabolic activation/detoxication of PAH and the relevance of phase II conjugation reactions to human lung carcinogenesis.

  13. Ageratum conyzoides L. inhibits 5-alpha-reductase gene expression in human prostate cells and reduces symptoms of benign prostatic hypertrophy in otherwise healthy men in a double blind randomized placebo controlled clinical study.

    Science.gov (United States)

    Detering, Matthew; Steels, Elizabeth; Koyyalamudi, Sundar Rao; Allifranchini, Elena; Bocchietto, Elena; Vitetta, Luis

    2017-10-19

    A double-blind, randomized, placebo-controlled clinical trial assessed the efficacy and safety of Ageratum conyzoides in treating benign prostatic hypertrophy (BPH). In this study, 109 men with medically diagnosed BPH, aged 41-76 years, were administered the investigational product, A. conyzoides extract at a dose of 250 mg/d or placebo, q.d. for 12 weeks. The primary outcome measures were the International Prostate Symptom Score (IPSS), daily urinary frequency and safety evaluations. The secondary outcome measures were testosterone, dihydrotestosterone, oestradiol, sex hormone binding globulin (SHBG), Dehydroepiandrosterone sulfate (DHEA-S) and cortisol levels, and prostate specific antigen (PSA), lipids, blood glucose, the Aging Male's Symptom (AMS) Score and sexual function assessed by Derogatis Interview for Sexual Functioning-Self Report (DISF-SR). The effect of A. conyzoides L extract on gene expression of 5-alpha-reductase in human prostate cells was also investigated to elucidate a potential mechanism of action. The clinical study, showed a significant reduction in total IPSS score (p prostate epithelial cells. The overall results indicate that A. conyzoides may be an effective treatment for reducing symptoms of BPH in healthy men, in part, through inhibition of 5-alpha-reductase enzyme activity. © 2017 BioFactors, 2017. © 2017 International Union of Biochemistry and Molecular Biology.

  14. Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

    DEFF Research Database (Denmark)

    Glarborg, Peter; Marshall, Paul

    2013-01-01

    A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts satisfact...... by the competition between chain‐branching and ‐propagating steps; modeling predictions are particularly sensitive to the branching fraction for the OCS + O reaction to form CO + SO or CO2 + S.......A detailed chemical kinetic model for oxidation of carbonyl sulfide (OCS) has been developed, based on a critical evaluation of data from the literature. The mechanism has been validated against experimental results from batch reactors, flow reactors, and shock tubes. The model predicts...

  15. Reactive Carbonyl Species Mediate ABA Signaling in Guard Cells.

    Science.gov (United States)

    Islam, Md Moshiul; Ye, Wenxiu; Matsushima, Daiki; Munemasa, Shintaro; Okuma, Eiji; Nakamura, Yoshimasa; Biswas, Sanaullah; Mano, Jun'ichi; Murata, Yoshiyuki

    2016-12-01

    Drought is responsible for a massive reduction in crop yields. In response to drought, plants synthesize the hormone ABA, which induces stomatal closure, thus reducing water loss. In guard cells, ABA triggers production of reactive oxygen species (ROS), which is mediated by NAD(P)H oxidases. The production of ROS is a key factor for ABA-induced stomatal closure, but it remains to be clarified how the production of ROS is transduced into downstream signaling components in guard cells. We investigated roles of reactive carbonyl species (RCS) in ABA-induced stomatal closure using transgenic tobacco (Nicotiana tabacum) overexpressing Arabidopsis 2-alkenal reductase (AER-OE), which scavenges RCS. ABA and hydrogen peroxide (H2O2) induced accumulation of RCS including acrolein and 4-hydroxy-(E)-2-nonenal in wild-type tobacco but not in AER-OE. Stomatal closure and RCS accumulation in response to ABA and H2O2 were inhibited in AER-OE unlike in the wild type, while ABA-induced H2O2 production in guard cells was observed in AER-OE as well as in the wild type. Moreover, ABA inhibited inward-rectifying K(+) channels in wild-type guard cells but not in AER-OE guard cells. These results suggest that RCS is involved in ABA-induced stomatal closure and functions downstream of H2O2 production in the ABA signaling pathway in guard cells. © The Authors 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  16. Carbonyl Compounds Generated from Electronic Cigarettes

    Directory of Open Access Journals (Sweden)

    Kanae Bekki

    2014-10-01

    Full Text Available Electronic cigarettes (e-cigarettes are advertised as being safer than tobacco cigarettes products as the chemical compounds inhaled from e-cigarettes are believed to be fewer and less toxic than those from tobacco cigarettes. Therefore, continuous careful monitoring and risk management of e-cigarettes should be implemented, with the aim of protecting and promoting public health worldwide. Moreover, basic scientific data are required for the regulation of e-cigarette. To date, there have been reports of many hazardous chemical compounds generated from e-cigarettes, particularly carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal, which are often found in e-cigarette aerosols. These carbonyl compounds are incidentally generated by the oxidation of e-liquid (liquid in e-cigarette; glycerol and glycols when the liquid comes in contact with the heated nichrome wire. The compositions and concentrations of these compounds vary depending on the type of e-liquid and the battery voltage. In some cases, extremely high concentrations of these carbonyl compounds are generated, and may contribute to various health effects. Suppliers, risk management organizations, and users of e-cigarettes should be aware of this phenomenon.

  17. Carbonyl compounds generated from electronic cigarettes.

    Science.gov (United States)

    Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2014-10-28

    Electronic cigarettes (e-cigarettes) are advertised as being safer than tobacco cigarettes products as the chemical compounds inhaled from e-cigarettes are believed to be fewer and less toxic than those from tobacco cigarettes. Therefore, continuous careful monitoring and risk management of e-cigarettes should be implemented, with the aim of protecting and promoting public health worldwide. Moreover, basic scientific data are required for the regulation of e-cigarette. To date, there have been reports of many hazardous chemical compounds generated from e-cigarettes, particularly carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal, which are often found in e-cigarette aerosols. These carbonyl compounds are incidentally generated by the oxidation of e-liquid (liquid in e-cigarette; glycerol and glycols) when the liquid comes in contact with the heated nichrome wire. The compositions and concentrations of these compounds vary depending on the type of e-liquid and the battery voltage. In some cases, extremely high concentrations of these carbonyl compounds are generated, and may contribute to various health effects. Suppliers, risk management organizations, and users of e-cigarettes should be aware of this phenomenon.

  18. Millimeter wave spectra of carbonyl cyanide

    Science.gov (United States)

    Bteich, S. B.; Tercero, B.; Cernicharo, J.; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2016-07-01

    Context. More than 30 cyanide derivatives of simple organic molecules have been detected in the interstellar medium, but only one dicarbonitrile has been found and that very recently. There is still a lack of high-resolution spectroscopic data particularly for dinitriles derivatives. The carbonyl cyanide molecule is a new and interesting candidate for astrophysical detection. It could be formed by the reaction of CO and CN radicals, or by substitution of the hydrogen atom by a cyano group in cyanoformaldehyde, HC(=O)CN, that has already been detected in the interstellar medium. Aims: The available data on the rotational spectrum of carbonyl cyanide is limited in terms of quantum number values and frequency range, and does not allow accurate extrapolation of the spectrum into the millimeter-wave range. To provide a firm basis for astrophysical detection of carbonyl cyanide we studied its millimeter-wave spectrum. Methods: The rotational spectrum of carbonyl cyanide was measured in the frequency range 152-308 GHz and analyzed using Watson's A- and S-reduction Hamiltonians. Results: The ground and first excited state of v5 vibrational mode were assigned and analyzed. More than 1100 distinct frequency lines of the ground state were fitted to produce an accurate set of rotational and centrifugal distortion constants up to the eighth order. The frequency predictions based on these constants should be accurate enough for astrophysical searches in the frequency range up to 500 GHz and for transition involving energy levels with J ≤ 100 and Ka ≤ 42. Based on the results we searched for interstellar carbonyl cyanide in available observational data without success. Thus, we derived upper limits to its column density in different sources. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2011.0.00009.SV. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan) with NRC (Canada), NSC, and ASIAA (Taiwan), and KASI (Republic of

  19. Studies of Human 2,4-Dienoyl CoA Reductase Shed New Light on Peroxisomal β-Oxidation of Unsaturated Fatty Acids

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Tian; Wu, Dong; Ding, Wei; Wang, Jiangyun; Shaw, Neil; Liu, Zhi-Jie [Nankai; (Chinese Aca. Sci.)

    2012-10-15

    Peroxisomes play an essential role in maintaining fatty acid homeostasis. Although mitochondria are also known to participate in the catabolism of fatty acids via β-oxidation, differences exist between the peroxisomal and mitochondrial β-oxidation. Only peroxisomes, but not mitochondrion, can shorten very long chain fatty acids. Here, we describe the crystal structure of a ternary complex of peroxisomal 2,4-dienoyl CoA reductases (pDCR) with hexadienoyl CoA and NADP, as a prototype for comparison with the mitochondrial 2,4-dienoyl CoA reductase (mDCR) to shed light on the differences between the enzymes from the two organelles at the molecular level. Unexpectedly, the structure of pDCR refined to 1.84 Å resolution reveals the absence of the tyrosine-serine pair seen in the active site of mDCR, which together with a lysine and an asparagine have been deemed a hallmark of the SDR family of enzymes. Instead, aspartate hydrogen-bonded to the Cα hydroxyl via a water molecule seems to perturb the water molecule for protonation of the substrate. Our studies provide the first structural evidence for participation of water in the DCR-catalyzed reactions. Biochemical studies and structural analysis suggest that pDCRs can catalyze the shortening of six-carbon-long substrates in vitro. However, the Km values of pDCR for short chain acyl CoAs are at least 6-fold higher than those for substrates with 10 or more aliphatic carbons. Unlike mDCR, hinge movements permit pDCR to process very long chain polyunsaturated fatty acids.

  20. Carbonyl Emissions from Gasoline and Diesel Motor Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Destaillats, Hugo; Jakober, Chris A.; Robert, Michael A.; Riddle, Sarah G.; Destaillats, Hugo; Charles, M. Judith; Green, Peter G.; Kleeman, Michael J.

    2007-12-01

    Carbonyls from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization and chromatography-mass spectrometry analyses. Two internal standards were utilized based on carbonyl recovery, 4-fluorobenzaldehyde forcarbonyls and 6-fluoro-4-chromanone for>_C8 compounds. Gas- and particle-phase emissions for 39 aliphatic and 20 aromatic carbonyls ranged from 0.1 ? 2000 ?g/L fuel for LDVs and 1.8 - 27000 mu g/L fuel for HDDVs. Gas-phase species accounted for 81-95percent of the total carbonyls from LDVs and 86-88percent from HDDVs. Particulate carbonyls emitted from a HDDV under realistic driving conditions were similar to concentrations measured in a diesel particulate matter (PM) standard reference material. Carbonyls accounted for 19percent of particulate organic carbon (POC) emissions from low-emission LDVs and 37percent of POC emissions from three-way catalyst equipped LDVs. This identifies carbonyls as one of the largest classes of compounds in LDV PM emissions. The carbonyl fraction of HDDV POC was lower, 3.3-3.9percent depending upon operational conditions. Partitioning analysis indicates the carbonyls had not achieved equilibrium between the gas- and particle-phase under the dilution factors of 126-584 used in the current study.

  1. Rate of steroid double-bond reduction catalysed by the human steroid 5β-reductase (AKR1D1) is sensitive to steroid structure: implications for steroid metabolism and bile acid synthesis

    Science.gov (United States)

    Jin, Yi; Chen, Mo; Penning, Trevor M.

    2014-01-01

    Human AKR1D1 (steroid 5β-reductase/aldo-keto reductase 1D1) catalyses the stereospecific reduction of double bonds in Δ4-3-oxosteroids, a unique reaction that introduces a 90° bend at the A/B ring fusion to yield 5β-dihydrosteroids. AKR1D1 is the only enzyme capable of steroid 5β-reduction in humans and plays critical physiological roles. In steroid hormone metabolism, AKR1D1 serves mainly to inactivate the major classes of steroid hormones. AKR1D1 also catalyses key steps of the biosynthetic pathway of bile acids, which regulate lipid emulsification and cholesterol homoeostasis. Interestingly, AKR1D1 displayed a 20-fold variation in the kcat values, with steroid hormone substrates (e.g. aldosterone, testosterone and cortisone) having significantly higher kcat values than steroids with longer side chains (e.g. 7α-hydroxycholestenone, a bile acid precursor). Transient kinetic analysis revealed striking variations up to two orders of magnitude in the rate of the chemistry step (kchem), which resulted in different rate determining steps for the fast and slow substrates. By contrast, similar Kd values were observed for representative fast and slow substrates, suggesting similar rates of release for different steroid products. The release of NADP+ was shown to control the overall turnover for fast substrates, but not for slow substrates. Despite having high kchem values with steroid hormones, the kinetic control of AKR1D1 is consistent with the enzyme catalysing the slowest step in the catabolic sequence of steroid hormone transformation in the liver. The inherent slowness of the conversion of the bile acid precursor by AKR1D1 is also indicative of a regulatory role in bile acid synthesis. PMID:24894951

  2. Acute inhalation toxicity of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Benson, J.M.; Hahn, F.F.; Barr, E.B. [and others

    1995-12-01

    Carbonyl sulfide (COS), a colorless gas, is a side product of industrial procedures sure as coal hydrogenation and gasification. It is structurally related to and is a metabolite of carbon disulfide. COS is metabolized in the body by carbonic anhydrase to hydrogen sulfide (H{sub 2}S), which is thought to be responsible for COS toxicity. No threshold limit value for COS has been established. Results of these studies indicate COS (with an LC{sub 50} of 590 ppm) is slightly less acutely toxic than H{sub 2}S (LC{sub 50} of 440 ppm).

  3. Antiatherogenic effect of bisvanillyl-hydralazone, a new hydralazine derivative with antioxidant, carbonyl scavenger, and antiapoptotic properties.

    Science.gov (United States)

    Bouguerne, Benaissa; Belkheiri, Nadji; Bedos-Belval, Florence; Vindis, Cécile; Uchida, Koji; Duran, Hubert; Grazide, Marie-Hélène; Baltas, Michel; Salvayre, Robert; Nègre-Salvayre, Anne

    2011-06-01

    Reactive oxygen species (ROS) generated within the vascular wall trigger low-density lipoprotein (LDL) oxidation, lipid peroxidation, and carbonyl stress that are involved in atherogenesis. We recently reported that the antihypertensive drug, hydralazine, exhibits carbonyl scavenger and antiatherogenic properties, but only moderate antioxidant activity, so that high concentrations are required for inhibiting LDL oxidation. We aimed to develop agents sharing both antioxidant and carbonyl scavenger properties. We have synthesized a new hydralazine derivative, the bisvanillyl-hydralazone (BVH). BVH strongly inhibited LDL oxidation induced by copper and by human endothelial cells (HMEC-1), and prevented the formation of macrophagic foam cells. BVH reduced both the extracellular generation of ROS (superoxide anion and hydrogen peroxide) induced by oxidized LDL (oxLDL), as well as intracellular oxidative stress and proteasome activation, NFkappaB activation, and oxLDL-mediated proinflammatory signaling. In parallel, BVH prevented the carbonyl stress induced by oxLDL on cellular proteins, and blocked the apoptotic cascade as assessed by the inhibition of Bid cleavage, cytochrome C release, and DEVDase activation. Lastly, BVH prevented atherogenesis and carbonyl stress in apoE(-/-) mice. In conclusion, BVH is the prototype of a new class of antioxidant and carbonyl scavenger agents designed for new therapeutical approaches in atherosclerosis.

  4. Compostos carbonílicos atmosféricos: fontes, reatividade, níveis de concentração e efeitos toxicológicos Atmospheric carbonyl compounds: sources, reactivity, concentration levels and toxicologic effects

    Directory of Open Access Journals (Sweden)

    Marta Valéria Almeida Santana de Andrade

    2002-12-01

    Full Text Available In the last three decades carbonyl compounds, aldehydes and ketones, have received a great deal of attention due to their strong influence on photochemical smog formation and their recognized adverse human health effects. Carbonyl compounds are directly emitted into the atmosphere by combustion sources and also produced from photochemical oxidation of hydrocarbons and other organic compounds. In this paper it is presented a general overview about the carbonyl compounds sources, reactivity, concentration levels and toxicological effects.

  5. Bifunctional dendrons for multiple carbohydrate presentation via carbonyl chemistry

    Directory of Open Access Journals (Sweden)

    Davide Bini

    2014-07-01

    Full Text Available The synthesis of new dendrons of the generations 0, 1 and 2 with a double bond at the focal point and a carbonyl group at the termini has been carried out. The carbonyl group has been exploited for the multivalent conjugation to a sample saccharide by reductive amination and alkoxyamine conjugation.

  6. Electromagnetic properties of carbonyl iron and their microwave ...

    Indian Academy of Sciences (India)

    Electromagnetic properties of carbonyl iron and their microwave absorbing characterization as filler in silicone rubber. Yuping Duan Guofang ... The complex permittivity, permeability and microwave-absorbing properties of rubber composites filled with carbonyl iron are measured at frequencies from 2–18 GHz. The results ...

  7. Aldehydes as alkyl carbanion equivalents for additions to carbonyl compounds

    Science.gov (United States)

    Wang, Haining; Dai, Xi-Jie; Li, Chao-Jun

    2017-04-01

    Nucleophilic addition reactions of organometallic reagents to carbonyl compounds for carbon-carbon bond construction have played a pivotal role in modern chemistry. However, this reaction's reliance on petroleum-derived chemical feedstocks and a stoichiometric quantity of metal have prompted the development of many carbanion equivalents and catalytic metal alternatives. Here, we show that naturally occurring carbonyls can be used as latent alkyl carbanion equivalents for additions to carbonyl compounds, via reductive polarity reversal. Such 'umpolung' reactivity is facilitated by a ruthenium catalyst and diphosphine ligand under mild conditions, delivering synthetically valuable secondary and tertiary alcohols in up to 98% yield. The unique chemoselectivity exhibited by carbonyl-derived carbanion equivalents is demonstrated by their tolerance to protic reaction media and good functional group compatibility. Enantioenriched tertiary alcohols can also be accessed with the aid of chiral ligands, albeit with moderate stereocontrol. Such carbonyl-derived carbanion equivalents are anticipated to find broad utility in chemical bond formation.

  8. The Hydrolysis of Carbonyl Sulfide at Low Temperature: A Review

    Science.gov (United States)

    Zhao, Shunzheng; Yi, Honghong; Tang, Xiaolong; Jiang, Shanxue; Gao, Fengyu; Zhang, Bowen; Zuo, Yanran; Wang, Zhixiang

    2013-01-01

    Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transition metal oxides, rare earth metal oxides, mixed metal oxides, and nanometal oxides. The catalytic hydrolysis of COS is a first-order reaction with respect to carbonyl sulfide, while the reaction order of water changes as the reaction conditions change. The controlling steps are also different because the reaction conditions such as concentration of carbonyl sulfide, reaction temperature, water-air ratio, and reaction atmosphere are different. The hydrolysis of carbonyl sulfide is base-catalyzed reaction, and the force of the base site has an important effect on the hydrolysis of carbonyl sulfide. PMID:23956697

  9. Pseudoazurin-nitrite reductase interactions.

    Science.gov (United States)

    Impagliazzo, Antonietta; Krippahl, Ludwig; Ubbink, Marcellus

    2005-09-01

    The nitrite reductase-binding site on pseudoazurin has been determined by using NMR chemical-shift perturbations. It comprises residues in the hydrophobic patch surrounding the exposed copper ligand His81 as well as several positively charged residues. The binding site is similar for both redox states of pseudoazurin, despite differences in the binding mode. The results suggest that pseudoazurin binds in a well-defined orientation. Docking simulations provide a putative structure of the complex with a binding site on nitrite reductase that has several hydrophobic and polar residues as well as a ridge of negatively charged side chains and a copper-to-copper distance of 14 A.

  10. Molybdenum-containing nitrite reductases: Spectroscopic characterization and redox mechanism.

    Science.gov (United States)

    Wang, Jun; Keceli, Gizem; Cao, Rui; Su, Jiangtao; Mi, Zhiyuan

    2017-01-01

    This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information are also advised. Nitrite-NO-cGMP has been considered as an important signaling pathway of NO in human cells. To date, all the four known human molybdenum-containing enzymes, xanthine oxidase, aldehyde oxidase, sulfite oxidase, and mitochondrial amidoxime-reducing component, have been shown to function as nitrite reductases under hypoxia by biochemical, cellular, or animal studies. Various spectroscopic techniques have been applied to investigate the structure and catalytic mechanism of these enzymes for more than 20 years. We summarize the published data on the applications of UV-vis and EPR spectroscopies, and X-ray crystallography in studying nitrite reductase activity of the four human molybdenum-containing enzymes. UV-vis has provided useful information on the redox active centers of these enzymes. The utilization of EPR spectroscopy has been critical in determining the coordination and redox status of the Mo center during catalysis. Despite the lack of substrate-bound crystal structures of these nitrite reductases, valuable structural information has been obtained by X-ray crystallography. To fully understand the catalytic mechanisms of these physiologically/pathologically important nitrite reductases, structural studies on substrate-redox center interaction are needed.

  11. Dihydrofolate reductase: A potential drug target in trypanosomes and leishmania

    Science.gov (United States)

    Zuccotto, Fabio; Martin, Andrew C. R.; Laskowski, Roman A.; Thornton, Janet M.; Gilbert, Ian H.

    1998-05-01

    Dihydrofolate reductase has successfully been used as a drug target in the area of anti-cancer, anti-bacterial and anti-malarial chemotherapy. Little has been done to evaluate it as a drug target for treatment of the trypanosomiases and leishmaniasis. A crystal structure of Leishmania major dihydrofolate reductase has been published. In this paper, we describe the modelling of Trypanosoma cruzi and Trypanosoma brucei dihydrofolate reductases based on this crystal structure. These structures and models have been used in the comparison of protozoan, bacterial and human enzymes in order to highlight the different features that can be used in the design of selective anti-protozoan agents. Comparison has been made between residues present in the active site, the accessibility of these residues, charge distribution in the active site, and the shape and size of the active sites. Whilst there is a high degree of similarity between protozoan, human and bacterial dihydrofolate reductase active sites, there are differences that provide potential for selective drug design. In particular, we have identified a set of residues which may be important for selective drug design and identified a larger binding pocket in the protozoan than the human and bacterial enzymes.

  12. High throughput assay for evaluation of reactive carbonyl scavenging capacity

    Directory of Open Access Journals (Sweden)

    N. Vidal

    2014-01-01

    Full Text Available Many carbonyl species from either lipid peroxidation or glycoxidation are extremely reactive and can disrupt the function of proteins and enzymes. 4-hydroxynonenal and methylglyoxal are the most abundant and toxic lipid-derived reactive carbonyl species. The presence of these toxics leads to carbonyl stress and cause a significant amount of macromolecular damages in several diseases. Much evidence indicates trapping of reactive carbonyl intermediates may be a useful strategy for inhibiting or decreasing carbonyl stress-associated pathologies. There is no rapid and convenient analytical method available for the assessment of direct carbonyl scavenging capacity, and a very limited number of carbonyl scavengers have been identified to date, their therapeutic potential being highlighted only recently. In this context, we have developed a new and rapid sensitive fluorimetric method for the assessment of reactive carbonyl scavengers without involvement glycoxidation systems. Efficacy of various thiol- and non-thiol-carbonyl scavenger pharmacophores was tested both using this screening assay adapted to 96-well microplates and in cultured cells. The scavenging effects on the formation of Advanced Glycation End-product of Bovine Serum Albumin formed with methylglyoxal, 4-hydroxynonenal and glucose-glycated as molecular models were also examined. Low molecular mass thiols with an α-amino-β-mercaptoethane structure showed the highest degree of inhibitory activity toward both α,β-unsaturated aldehydes and dicarbonyls. Cysteine and cysteamine have the best scavenging ability toward methylglyoxal. WR-1065 which is currently approved for clinical use as a protective agent against radiation and renal toxicity was identified as the best inhibitor of 4-hydroxynonenal.

  13. Co-clinical Analysis of a Genetically Engineered Mouse Model and Human Prostate Cancer Reveals Significance of NKX3.1 Expression for Response to 5α-reductase Inhibition.

    Science.gov (United States)

    Dutta, Aditya; Panja, Sukanya; Virk, Renu K; Kim, Jaime Yeji; Zott, Roseann; Cremers, Serge; Golombos, David M; Liu, Deli; Mosquera, Juan Miguel; Mostaghel, Elahe A; Barbieri, Christopher E; Mitrofanova, Antonina; Abate-Shen, Cory

    2017-10-01

    Although men on active surveillance for prostate cancer (PCa) may benefit from intervention with 5α-reductase inhibitors (5-ARIs), it has not been resolved whether 5-ARIs are effective for delaying disease progression and, if so, whether specific patients are more likely to benefit. To identify molecular features predictive of patient response to 5-ARIs. Nkx3.1 mutant mice, a model of early-stage PCa, were treated with the 5-ARI finasteride, and histopathological and molecular analyses were performed. Cross-species computational analyses were used to compare expression profiles for treated mice with those of patients who had received 5-ARIs before prostatectomy. Finasteride administered to Nkx3.1 mutant mice. 5-ARI-treated patient specimens obtained retrospectively. Endpoints in mice included histopathology, immunohistochemistry, and molecular profiling. GraphPad Prism software, R-studio, and Matlab were used for statistical and data analyses. Finasteride treatment of Nkx3.1 mutant mice resulted in a significant reduction in prostatic intraepithelial neoplasia (PIN), as evident from histopathological and expression profiling analyses. Cross-species computational analysis comparing finasteride-treated mice with two independent 5-ARI-treated patient cohorts showed that reduced NKX3.1 expression is predictive of response to 5-ARI. A limitation of the study is that these retrospective human cohorts have relatively few patients with limited clinical outcome data. Future prospective clinical trials are needed to validate whether stratifying patients on the basis of NKX3.1 expression improves the benefit of 5-ARIs during active surveillance. This co-clinical study implicates NKX3.1 status as a predictor of response to 5-ARIs, and suggests that molecular features, including NKX3.1 expression, may help to identify PCa patients most likely to benefit from 5-ARIs during active surveillance. The aim of precision cancer prevention is to tailor interventions on the basis of

  14. Synthesis, biological activity, and three-dimensional quantitative structure-activity relationship model for a series of benzo[c]quinolizin-3-ones, nonsteroidal inhibitors of human steroid 5alpha-reductase 1.

    Science.gov (United States)

    Occhiato, Ernesto G; Ferrali, Alessandro; Menchi, Gloria; Guarna, Antonio; Danza, Giovanna; Comerci, Alessandra; Mancina, Rosa; Serio, Mario; Garotta, Gianni; Cavalli, Andrea; De Vivo, Marco; Recanatini, Maurizio

    2004-07-01

    New 5alpha-reductase 1 (5alphaR-1) inhibitors were designed to complete a consistent set of analogues suitable for a 3D QSAR study. These compounds were synthesized by a modification of the aza-Robinson annulation, further functionalized by Pd-catalyzed cross-coupling processes, and were tested with human 5alphaR-1 expressed in Chinese hamster ovary 1827 cells. It turned out that the potency of the resulting inhibitors was strongly dependent on the type of substitution at the 8 position, with the IC(50) values ranging from 8.1 to 1050 nM. The construction of this homogeneous set of molecules allowed a 3D QSAR study. In particular, comparative molecular field analysis (CoMFA) was used to correlate the potency of the inhibitors with their physicochemical features. Highly accurate evaluations of the atomic point charges were carried out by means of quantum chemical calculations at the DFT/B3LYP level of theory followed by the RESP fitting procedure. It turned out that increasing the reliability of electrostatic parameters greatly affected the statistical results of the QSAR analysis. The 3D QSAR model proposed could be very useful in the further development of 5alphaR-1 inhibitors, which are suitable candidates to be evaluated as drugs in the treatment of 5alphaR-1 related diseases such as acne and alopecia in men and hirsutism in women.

  15. Development of Caco-2 cells co-expressing CYP3A4 and NADPH-cytochrome P450 reductase using a human artificial chromosome for the prediction of intestinal extraction ratio of CYP3A4 substrates.

    Science.gov (United States)

    Takenaka, Toru; Kazuki, Kanako; Harada, Naomoto; Kuze, Jiro; Chiba, Masato; Iwao, Takahiro; Matsunaga, Tamihide; Abe, Satoshi; Oshimura, Mitsuo; Kazuki, Yasuhiro

    2017-02-01

    The Caco-2 cells co-expressing cytochrome P450 (CYP) 3A4 and NADPH-cytochrome P450 reductase (CPR) were developed using a human artificial chromosome (HAC) vector. The CYP3A4 and CPR genes were cloned into the HAC vector in CHO cells using the Cre-loxP system, and the microcell-mediated chromosome transfer technique was used to transfer the CYP3A4-CPR-HAC vector to Caco-2 cells. After seeding onto semipermeable culture inserts, the CYP3A4-CPR-HAC/Caco-2 cells were found to form tight monolayers, similar to the parental cells, as demonstrated by the high transepithelial electrical resistance (TEER) value and comparable permeability of non-CYP3A4 substrates between parent and CYP3A4-CPR-HAC/Caco-2 cell monolayers. The metabolic activity of CYP3A4 (midazolam 1'-hydroxylase activity) in the CYP3A4-CPR-HAC/Caco-2 cells was constant from 22 to 35 passages, indicating that HAC vectors conferred sufficient and sustained CYP3A4 activity to CYP3A4-CPR-HAC/Caco-2 cells. The strong relationship between the metabolic extraction ratios (ER) obtained from the CYP3A4-CPR-HAC/Caco-2 cells and calculated intestinal extraction ratios in humans (Eg) from reported intestinal availability (Fg) was found for 17 substrates of CYP3A4 (r2 = 0.84). The present study suggests that the CYP3A4-CPR-HAC/Caco-2 cell monolayer can serve as an in vitro tool that facilitates the prediction of intestinal extraction ratio (or availability) in humans. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

  16. Crystal structure and catalytic characterization of the dehydrogenase/reductase SDR family member 4 (DHRS4) from Caenorhabditis elegans.

    Science.gov (United States)

    Kisiela, Michael; Faust, Annette; Ebert, Bettina; Maser, Edmund; Scheidig, Axel J

    2017-11-19

    The human dehydrogenase/reductase SDR family member 4 (DHRS4) is a tetrameric protein that is involved in the metabolism of several aromatic carbonyl compounds, steroids, and bile acids. The only invertebrate DHRS4 that has been characterized to date is that from the model organism Caenorhabditis elegans. We have previously cloned and initially characterized this protein that was recently annotated as DHRS4_CAEEL in the UniProtKB database. Crystallization and X-ray diffraction studies of the full-length DHRS4_CAEEL protein in complex with diacetyl revealed its tetrameric structure and showed that two subunits are connected via an intermolecular disulfide bridge that is formed by N-terminal cysteine residues (Cys5) of each protein chain, which increases the enzymatic activity. A more detailed biochemical and catalytic characterization shows that DHRS4_CAEEL shares some properties with human DHRS4 such as relatively low substrate affinities with aliphatic α-diketones and a preference for aromatic dicarbonyls such as isatin, with a 30-fold lower Km value compared with the human enzyme. Moreover, DHRS4_CAEEL is active with aliphatic aldehydes (e.g. hexanal), while human DHRS4 is not. Dehydrogenase activity with alcohols was only observed with aromatic alcohols. Protein thermal shift assay revealed a stabilizing effect of phosphate buffer that was accompanied by an increase in catalytic activity of more than two-fold. The study of DHRS4 homologs in simple lineages such as C. elegans may contribute to our understanding of the original function of this protein that has been shaped by evolutionary processes in the course of the development from invertebrates to higher mammalian species. Structural data are available in the PDB under the accession numbers 5OJG and 5OJI. © 2017 Federation of European Biochemical Societies.

  17. Biliverdin Reductase: a Target for Cancer Therapy?

    Directory of Open Access Journals (Sweden)

    Peter eGibbs

    2015-06-01

    Full Text Available Biliverdin reductase (BVR is a multifunctional protein that is the primary source of the potent antioxidant, bilirubin. BVR regulates activities/functions in the insulin/IGF-1/IRK/PI3K/MAPK pathways. Activation of certain kinases in these pathways is/are hallmark(s of cancerous cells. The protein is a scaffold/bridge and intracellular transporter of kinases that regulate growth and proliferation of cells, including PKCs, ERK and Akt, and their targets including NF-κB, Elk1, HO-1 and iNOS. The scaffold and transport functions enable activated BVR to relocate from the cytosol to the nucleus or to the plasma membrane, depending on the activating stimulus. This enables the reductase to function in diverse signaling pathways. And, its expression at the transcript and protein levels are increased in human tumors and the infiltrating T-cells, monocytes and circulating lymphocytes, as well as the circulating and infiltrating macrophages. These functions suggest that the cytoprotective role of BVR may be permissive for cancer/tumor growth. In this review, we summarize the recent developments that define the pro-growth activities of BVR, particularly with respect to its input into the MAPK signaling pathway and present evidence that BVR-based peptides inhibit activation of protein kinases, including MEK, PKCδ and ERK as well as downstream targets including Elk1 and iNOS, and thus offers a credible novel approach to reduce cancer cell proliferation.

  18. Cobalt carbonyl-catalyzed carbonylation of functionalized aziridines to versatile β-lactam building blocks.

    Science.gov (United States)

    Piens, Nicola; Van Hecke, Kristof; Vogt, Dieter; D'hooghe, Matthias

    2017-06-07

    The Co2(CO)8-catalyzed carbonylation of different classes of non-activated aziridines with diverse substitution patterns was investigated. Special attention was devoted to selectivity issues and reaction optimization. This study resulted in the regio- and stereospecific synthesis of 24 novel β-lactam target structures in high yields on a multigram scale. The synthetic potential of the newly obtained azetidin-2-ones was illustrated via ring-expansion, ring-closure, and/or side chain-functionalization protocols to provide a straightforward entry to novel pyrrolidines, C-fused bi- and tricyclic β-lactams and monocyclic carbapenem analogs.

  19. Efficiency of Carbonyl Iron in Prevention of Anaemia in Piglets

    Directory of Open Access Journals (Sweden)

    M. Svoboda

    2007-01-01

    Full Text Available The aim of this study was to evaluate efficiency of elemental iron preparation in the form of carbonyl iron in prevention of iron deficiency in piglets. The piglets in group I (n = 14 were given 210 mg of carbonyl iron orally at the age of 3 days. The piglets in group II (n = 15 received 210 mg of carbonyl iron orally on days 3 and 9. In group III (n = 14 the piglets were injected i.m. with 200 mg Fe3+ as iron dextran. Fourteen days after birth, haemoglobin concentration in group I started to decrease and the piglets developed anaemia. In group II, at the age of 28 days, Hb dropped below 80 g/l and the piglets developed anaemia. Under conditions of this trial, the oral administration of carbonyl iron did not prevent development of iron deficiency in piglets.

  20. Keto-Enol Tautomers in a Carbonyl Phosphonium Salt

    Science.gov (United States)

    Berry, David E.; Patenaude, G. W.

    2002-04-01

    Supplementary NMR data is provided for an experiment previously published in this Journal describing the synthesis of carbonyl-stabilized ylides. The new data suggest that the keto-enol tautomerism is taking place in the phosphonium ion.

  1. The human selenoprotein VCP-interacting membrane protein (VIMP) is non-globular and harbors a reductase function in an intrinsically disordered region

    DEFF Research Database (Denmark)

    Christensen, Lea Cecilie; Jensen, Njal Winther; Lages Lino Vala, Andrea

    2012-01-01

    The human selenoprotein VIMP (VCP-interacting membrane protein)/SelS (selenoprotein S) localizes to the endoplasmic reticulum (ER) membrane and is involved in the process of ER-associated degradation (ERAD). To date, little is known about the presumed redox activity of VIMP, its structure and how...

  2. Synthesis of main-chain metal carbonyl organometallic macromolecules (MCMCOMs).

    Science.gov (United States)

    Cao, Kai; Murshid, Nimer; Wang, Xiaosong

    2015-04-01

    Synthesis of main-chain metal carbonyl organometallic macromolecules (MCMCOMs) is difficult, mainly due to the instability of metal carbonyl complexes. Despite its challenge a number of MCMCOMs has been prepared by strategically using organometallic, organic, and polymer synthetic chemistry. Main contributions to this research field were reported by the groups of Tyler, Pannell, and Wang and are briefly summarized in this article. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Chemical probes for analysis of carbonylated proteins: a review.

    Science.gov (United States)

    Yan, Liang-Jun; Forster, Michael J

    2011-05-15

    Protein carbonylation is a major form of protein oxidation and is widely used as an indicator of oxidative stress. Carbonyl groups do not have distinguishing UV or visible, spectrophotometric absorbance/fluorescence characteristics and thus their detection and quantification can only be achieved using specific chemical probes. In this paper, we review the advantages and disadvantages of several chemical probes that have been and are still being used for protein carbonyl analysis. These probes include 2,4-dinitrophenylhydazine (DNPH), tritiated sodium borohydride ([(3)H]NaBH(4)), biotin-containing probes, and fluorescence probes. As our discussions lean toward gel-based approaches, utilizations of these probes in 2D gel-based proteomic analysis of carbonylated proteins are illustrated where applicable. Analysis of carbonylated proteins by ELISA, immunofluorescent imaging, near infrared fluorescence detection, and gel-free proteomic approaches are also discussed where appropriate. Additionally, potential applications of blue native gel electrophoresis as a tool for first dimensional separation in 2D gel-based analysis of carbonylated proteins are discussed as well. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Cytoskeletal protein carbonylation and degradation in experimental autoimmune encephalomyelitis

    Science.gov (United States)

    Smerjac, Suzanne M.; Bizzozero, Oscar A.

    2013-01-01

    Protein carbonylation, the non-enzymatic addition of aldehydes or ketones to specific amino acid residues, has been implicated in the pathophysiology of multiple sclerosis (MS). In this study we investigated whether protein carbonyls (PCOs) also accumulate in the spinal cord of Lewis rats with acute experimental autoimmune encephalomyelitis (EAE). Western blots analysis after derivatization with dinitrophenyl hydrazine (oxyblot) showed elevated protein carbonylation at the time of maximal clinical disability. During the same period glutathione levels were substantially reduced, suggesting a causal relationship between these two markers. In contrast, lipid peroxidation products accumulated in EAE spinal cord well before the appearance of neurological symptoms. Carbonyl staining was not restricted to inflammatory lesions but present throughout the spinal cord particularly in neuronal cell bodies and axons. By 2-dimensional-oxyblot we identified several cytoskeletal proteins, including β-actin, GFAP and the neurofilament proteins as the major targets of carbonylation. These findings were confirmed by pull-down experiments, which also showed an increase in the number of carbonylated β-actin molecules and a decrease in that of oxidized neurofilament proteins in EAE. These data suggest the possibility that oxidation targets neurofilament proteins for degradation, which may contribute to axonal pathology observed in MS and EAE. PMID:18088377

  5. Inhibition of glutathione S-transferase activity in human melanoma cells by alfa, beta-unsaturated carbonyl derivatives : effects of acrolein, cinnamaldehyde, citral, crotonaldehyde, curcumin, ethacrynic acid, and trans-2-hexenal

    NARCIS (Netherlands)

    Iersel, M.L.P.S. van; Ploemen, J.P.H.T.M.; Struik, I.; Amersfoort, C. van; Keyzer, A.E.; Schefferlie, J.G.; Bladeren, P.J. van

    1996-01-01

    The glutathione S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene in intact human IGR-39 melanoma cells was determined by the quantification by HPLC-analysis of the excreted glutathione (GSH) conjugate (S-(2,4-dinitrophenyl)glutathione; DNPSG). The major GST subunit expressed in these

  6. The oceanic cycle and global atmospheric budget of carbonyl sulfide

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, P.S.

    1994-12-31

    A significant portion of stratospheric air chemistry is influenced by the existence of carbonyl sulfide (COS). This ubiquitous sulfur gas represents a major source of sulfur to the stratosphere where it is converted to sulfuric acid aerosol particles. Stratospheric aerosols are climatically important because they scatter incoming solar radiation back to space and are able to increase the catalytic destruction of ozone through gas phase reactions on particle surfaces. COS is primarily formed at the surface of the earth, in both marine and terrestrial environments, and is strongly linked to natural biological processes. However, many gaps in the understanding of the global COS cycle still exist, which has led to a global atmospheric budget that is out of balance by a factor of two or more, and a lack of understanding of how human activity has affected the cycling of this gas. The goal of this study was to focus on COS in the marine environment by investigating production/destruction mechanisms and recalculating the ocean-atmosphere flux.

  7. Protective effect of phenolic compounds on carbonyl-amine reactions produced by lipid-derived reactive carbonyls.

    Science.gov (United States)

    Hidalgo, Francisco J; Delgado, Rosa M; Zamora, Rosario

    2017-08-15

    The degradation of phenylalanine initiated by 2-pentenal, 2,4-heptadienal, 4-oxo-2-pentenal, 4,5-epoxy-2-heptenal, or 4,5-epoxy-2-decenal in the presence of phenolic compounds was studied to determine the structure-activity relationship of phenolic compounds on the protection of amino compounds against modifications produced by lipid-derived carbonyls. The obtained results showed that flavan-3-ols were the most efficient phenolic compounds followed by single m-diphenols. The effectiveness of these compounds was found to be related to their ability to trap rapidly the carbonyl compound, avoiding in this way the reaction of the carbonyl compound with the amino acid. The ability of flavan-3-ols for this reaction is suggested to be related to the high electronic density existing in some of the aromatic carbons of their ring A. This is the first report showing that carbonyl-phenol reactions involving lipid-derived reactive carbonyls can be produced more rapidly than carbonyl-amine reactions, therefore providing a satisfactory protection of amino compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. [Aldehyde reductase activity and blood aldo-keto reductase spectrum in adolescents with neuroendocrine obesity].

    Science.gov (United States)

    Kuleshova, D K; Davydov, V V; Shvets, V N

    2012-01-01

    Investigation of aldehyde-reductase activity and blood aldo-keto reductase spectrum has been performed in 13-15 and 16-18-years old adolescents with obesity to clear up the mechanisms of neuroendocrine obesity at the age of puberty. It has been established that basal aldehyde reductase activity and blood aldo-keto reductase spectrum of healthy adolescents in early puberty do not differ from those of healthy adolescents in late puberty. A decreased aldehyde reductase activity and some alterations in blood aldo-keto reductase spectrum have been observed in late puberty in adolescents with neuroendocrine obesity. In adolescents with obesity there have been registered some changes in blood aldo-keto reductase spectrum which are not accompanied by any alterations in its aldehyde reductase activity. The results obtained suggest that certain prerequisites are formed in late puberty to complicate the course of neuroendocrine obesity.

  9. Role of Protein Carbonylation in Skeletal Muscle Mass Loss Associated with Chronic Conditions

    Directory of Open Access Journals (Sweden)

    Esther Barreiro

    2016-05-01

    Full Text Available Muscle dysfunction, characterized by a reductive remodeling of muscle fibers, is a common systemic manifestation in highly prevalent conditions such as chronic heart failure (CHF, chronic obstructive pulmonary disease (COPD, cancer cachexia, and critically ill patients. Skeletal muscle dysfunction and impaired muscle mass may predict morbidity and mortality in patients with chronic diseases, regardless of the underlying condition. High levels of oxidants may alter function and structure of key cellular molecules such as proteins, DNA, and lipids, leading to cellular injury and death. Protein oxidation including protein carbonylation was demonstrated to modify enzyme activity and DNA binding of transcription factors, while also rendering proteins more prone to proteolytic degradation. Given the relevance of protein oxidation in the pathophysiology of many chronic conditions and their comorbidities, the current review focuses on the analysis of different studies in which the biological and clinical significance of the modifications induced by reactive carbonyls on proteins have been explored so far in skeletal muscles of patients and animal models of chronic conditions such as COPD, disuse muscle atrophy, cancer cachexia, sepsis, and physiological aging. Future research will elucidate the specific impact and sites of reactive carbonyls on muscle protein content and function in human conditions.

  10. Fatty acyl-CoA reductase

    Energy Technology Data Exchange (ETDEWEB)

    Reiser, Steven E.; Somerville, Chris R.

    1998-12-01

    The present invention relates to bacterial enzymes, in particular to an acyl-CoA reductase and a gene encoding an acyl-CoA reductase, the amino acid and nucleic acid sequences corresponding to the reductase polypeptide and gene, respectively, and to methods of obtaining such enzymes, amino acid sequences and nucleic acid sequences. The invention also relates to the use of such sequences to provide transgenic host cells capable of producing fatty alcohols and fatty aldehydes.

  11. Identification of carbonylated lipids from different phospholipid classes by shotgun and LC-MS lipidomics.

    Science.gov (United States)

    Ni, Zhixu; Milic, Ivana; Fedorova, Maria

    2015-07-01

    Oxidized lipids play a significant role in the pathogenesis of numerous oxidative stress-related human disorders, such as atherosclerosis, obesity, inflammation, and autoimmune diseases. Lipid peroxidation, induced by reactive oxygen and nitrogen species, yields a high variety of modified lipids. Among them, carbonylated lipid peroxidation products (oxoLPP), formed by oxidation of the fatty acid moiety yielding aldehydes or ketones (carbonyl groups), are electrophilic compounds that are able to modify nucleophilic substrates like proteins, nucleic acid, and aminophospholipids. Some carbonylated phosphatidylcholines possess even pro-inflammatory activities. However, little is known about oxoLPP derived from other phospholipid (PL) classes. Here, we present a new analytical strategy based on the mass spectrometry (MS) of PL-oxoLPP derivatized with 7-(diethylamino)coumarin-3-carbohydrazide (CHH). Shotgun MS revealed many oxoLPP derived from in vitro oxidized glycerophosphatidylglycerols (PG, 31), glycerophosphatidylcholine (PC, 23), glycerophosphatidylethanolamine (PE, 34), glycerophosphatidylserines (PS, 7), glycerophosphatidic acids (PA, 17), and phosphatidylinositiolphosphates (PIP, 6) vesicles. This data were used to optimize LipidXplorer-assisted identification, and a python-based post-processing script was developed to increase both throughput and accuracy. When applied to full lipid extracts from rat primary cardiomyocytes treated with peroxynitrite donor SIN-1, ten PL-bound oxoLPP were unambiguously identified by LC-MS, including two PC-, two PE-, one PG-, two PS-, and three PA-derived species. Some of the well-known carbonylated PC were detected, while most PL-oxoLPP were shown for the first time.

  12. The nitric oxide reductase activity of cytochrome c nitrite reductase from Escherichia coli.

    Science.gov (United States)

    van Wonderen, Jessica H; Burlat, Bénédicte; Richardson, David J; Cheesman, Myles R; Butt, Julea N

    2008-04-11

    Cytochrome c nitrite reductase (NrfA) from Escherichia coli has a well established role in the respiratory reduction of nitrite to ammonium. More recently the observation that anaerobically grown E. coli nrf mutants were more sensitive to NO. than the parent strain led to the proposal that NrfA might also participate in NO. detoxification. Here we describe protein film voltammetry that presents a quantitative description of NrfA NO. reductase activity. NO. reduction is initiated at similar potentials to NrfA-catalyzed reduction of nitrite and hydroxylamine. All three activities are strongly inhibited by cyanide. Together these results suggest a common site for reduction of all three substrates as axial ligands to the lysine-coordinated NrfA heme rather than nonspecific NO. reduction at one of the four His-His coordinated hemes also present in each NrfA subunit. NO. reduction by NrfA is described by a K(m) of the order of 300 microm. The predicted turnover number of approximately 840 NO. s(-1) is much higher than that of the dedicated respiratory NO. reductases of denitrification and the flavorubredoxin and flavohemoglobin of E. coli that are also proposed to play roles in NO. detoxification. In considering the manner by which anaerobically growing E. coli might detoxify exogenously generated NO. encountered during invasion of a human host it appears that the periplasmically located NrfA should be effective in maintaining low NO. levels such that any NO. reaching the cytoplasm is efficiently removed by flavorubredoxin (K(m) approximately 0.4 microm).

  13. Oxygen and xenobiotic reductase activities of cytochrome P450.

    NARCIS (Netherlands)

    Goeptar, A.R.; Scheerens, H.; Vermeulen, N.P.E.

    1995-01-01

    The oxygen reductase and xenobiotic reductase activities of cytochrome P450 (P450) are reviewed. During the oxygen reductase activity of P450, molecular oxygen is reduced to superoxide anion radicals (O

  14. Structural analysis of human dihydrofolate reductase as a binary complex with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine reveals an unusual binding mode.

    Science.gov (United States)

    Cody, Vivian; Pace, Jim; Nowak, Jessica

    2011-10-01

    In order to understand the structure-activity profile observed for a series of substituted dibenz[b,f]azepine antifolates, the crystal structure of the binary complex of human dihydrofolate reductase (hDHFR) with the potent and selective inhibitor 2,4-diamino-6-{2'-O-(3-carboxypropyl)oxydibenz[b,f]-azepin-5-yl}methylpteridine (PT684) was determined to 1.8 Å resolution. These data revealed that the carboxylate side chain of PT684 occupies two alternate positions, neither of which interacts with the conserved Arg70 in the active-site pocket, which in turn hydrogen bonds to water. These observations are in contrast to those reported for the ternary complex of mouse DHFR (mDHFR) with NADPH [Cody et al. (2008), Acta Cryst. D64, 977-984], in which the 3-carboxypropyl side chain of PT684 was hydrolyzed to its hydroxyl derivative, PT684a. The crystallization conditions differed for the human and mouse DHFR crystals (100 mM K2HPO4 pH 6.9, 30% ammonium sulfate for hDHFR; 15 mM Tris pH 8.3, 75 mM sodium cacodylate, PEG 4K for mDHFR). Additionally, the side chains of Phe31 and Gln35 in the hDHFR complex have a single conformation, whereas in the mDHFR complex they occupied two alternative conformations. These data show that the hDHFR complex has a decreased active-site volume compared with the mDHFR complex, as reflected in a relative shift of helix C (residues 59-64) of 1.2 Å, and a shift of 1.5 Å compared with the ternary complex of Pneumocystis carinii DHFR (pcDHFR) with the parent dibenz[b,f]azepine PT653. These data suggest that the greater inhibitory potency of PT684 against pcDHFR is consistent with the larger active-site volume of pcDHFR and the predicted interactions of the carboxylate side chain with Arg75.

  15. An alternative method for monitoring carbonyls, and the development of a 24-port fully automated carbonyl sampler for PAMS program

    Energy Technology Data Exchange (ETDEWEB)

    Parmar, S.S.; Ugarova, L. [Atmospheric Analysis and Consulting, Ventura, CA (United States); Fernandes, C.; Guyton, J.; Lee, C.P. [Arizona Dept. of Environmental Quality, Phoenix, AZ (United States)

    1994-12-31

    The authors have investigated the possibility of collecting different aldehydes and ketones on different sorbents such as silica gel, molecular sieve and charcoal followed by solvent extraction, DNPH derivatization and HPLC/UV analysis. Carbonyl collection efficiencies for these sorbents were calculated relative to a DNPH coated C{sub 18} sep-pak cartridge. From a limited number of laboratory experiments, at various concentrations, it appears that silica gel tubes can be used for sampling aldehydes (collection efficiencies {approximately} 1), whereas charcoal tubes are suitable for collecting ketones. Molecular sieve was found to be unsuitable for collecting most of the carbonyl studied. The authors also report the development of a fully automated 24-port carbonyl sampler specially designed for EPA`s PAMS program.

  16. X-ray structure of trypanothione reductase from Crithidia fasciculata at 2. 4- angstrom resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kuriyan, J.; Xiangpeng Kong; Krishna, T.S.R.; Murgolo, N.J.; Field, H.; Cerami, A.; Henderson, G.B. (Rockefeller Univ., New York, NY (United States)); Sweet, R.M. (Brookhaven National Lab., Upton, NY (United States))

    1991-10-01

    Trypanosomes and related protozoan parasites lack glutathione reductase and possess instead a closely related enzyme that serves as the reductant of a bis(glutathione)-spermidien conjugate, trypanothione. The human and parasite enzymes have mutually exclusive substrate specificities, providing a route for the design of therapeutic agents by specific inhibition of the parasite enzyme. The authors report here the three-dimensional structure of trypanothione reductase from Crithidia fasciculata and show that it closely resembles the structure of human glutathione reductase. In particular, the core structure surrounding the catalytic machinery is almost identical in the two enzymes. However, significant differences are found at the substrate binding sites. A cluster of basic residues in glutathione reductase is replaced by neutral, hydrophobic, or acidic residues in trypanothione reductase, consistent with the nature of the spermidine linkage and the change in overall charge of the substrate from {minus}2 to +1, respectively. The binding site is more open in trypanothione reductase due to rotations of about 4{degree} in the domains that form in site, with relative shifts of as much as 2-3 {angstrom} in residues that can interact with potential inhibitors and complement previous modeling and mutagenesis studies on the two enzymes.

  17. Highly selective detection of carbon monoxide in living cells by palladacycle carbonylation-based surface enhanced Raman spectroscopy nanosensors.

    Science.gov (United States)

    Cao, Yue; Li, Da-Wei; Zhao, Li-Jun; Liu, Xiao-Yuan; Cao, Xiao-Ming; Long, Yi-Tao

    2015-10-06

    A novel nanosensor was explored for the highly selective detection of intracellular carbon monoxide (CO) by surface enhanced Raman spectroscopy (SERS) on the basis of palladacycle carbonylation. By assembling new synthesized palladacycles (PC) on the surface of gold nanoparticles (AuNPs), SERS nanosensors (AuNP/PC) were prepared with good SERS activity and reactivity with CO. When the AuNP/PC nanosensors were incubated with a CO-containing system, carbonylation of the PC assembled on AuNPs was initiated, and the corresponding SERS spectra of AuNP/PC changed significantly, which allowed the carbonylation reaction to be directly observed in situ. Upon SERS observation of CO-dependent carbonylation, this SERS nanosensor was used for the detection of CO under physiological conditions. Moreover, benefiting from the specificity of the reaction coupled with the fingerprinting feature of SERS, the developed nanosensor demonstrated high selectivity over other biologically relevant species. In vivo studies further indicated that CO in normal human liver cells and HeLa cells at concentrations as low as 0.5 μM were successfully detected with the proposed SERS strategy, demonstrating its great promise for the analytical requirements in studies of physiopathological events involved with CO.

  18. EXPRESSION AND CHARACTERIZATION OF FULL-LENGTH HUMAN HEME OXYGENASE-1: PRESENCE OF INTACT MEMBRANE-BINDING REGION LEADS TO INCREASED BINDING AFFINITY FOR NADPH-CYTOCHROME P450 REDUCTASE

    Science.gov (United States)

    Huber, Warren J.; Backes, Wayne L.

    2009-01-01

    Heme oxygenase (HO) is the chief regulatory enzyme in the oxidative degradation of heme to biliverdin. In the process of heme degradation, this NADPH and cytochrome P450 reductase (CPR)-dependent oxidation of heme also releases free iron and carbon monoxide. Much of the recent research involving heme oxygenase is done using a 30-kDa soluble form of the enzyme, which lacks the membrane binding region (C-terminal 23 amino acids). The goal of this study was to express and purify a full-length human HO-1 (hHO-1) protein; however, due to the lability of the full-length form, a rapid purification procedure was required. This was accomplished by use of a GST-tagged hHO-1 construct. Although the procedure permitted the generation of a full-length HO-1, this form was contaminated with a 30-kDa degradation product that could not be eliminated. Therefore, we attempted to remove a putative secondary thrombin cleavage site by a conservative mutation of amino acid 254, which replaces lysine with arginine. This mutation allowed the expression and purification of a full length hHO-1 protein. Unlike wild-type HO-1, the K254R mutant could be purified to a single 32-kDa protein capable of degrading heme at the same rate as the wild-type enzyme. The K254R full-length form had a specific activity of ~200–225 nmol bilirubin hr−1nmol−1 HO-1 as compared to ~140–150 nmol bilirubin hr−1nmol−1 for the WT form, which contains the 30-kDa contaminant. This is a 2–3-fold increase from the previously reported soluble 30-kDa HO-1, suggesting that the C-terminal 23 amino acids are essential for maximal catalytic activity. Because the membrane spanning domain is present, the full-length hHO-1 has the potential to incorporate into phospholipid membranes, which can be reconstituted at known concentrations, in combination with other ER-resident enzymes. PMID:17915953

  19. Expression and characterization of full-length human heme oxygenase-1: the presence of intact membrane-binding region leads to increased binding affinity for NADPH cytochrome P450 reductase.

    Science.gov (United States)

    Huber, Warren J; Backes, Wayne L

    2007-10-30

    Heme oxygenase-1 (HO-1) is the chief regulatory enzyme in the oxidative degradation of heme to biliverdin. In the process of heme degradation, HO-1 receives the electrons necessary for catalysis from the flavoprotein NADPH cytochrome P450 reductase (CPR), releasing free iron and carbon monoxide. Much of the recent research involving heme oxygenase has been done using a 30 kDa soluble form of the enzyme, which lacks the membrane binding region (C-terminal 23 amino acids). The goal of this study was to express and purify a full-length human HO-1 (hHO-1) protein; however, due to the lability of the full-length form, a rapid purification procedure was required. This was accomplished by use of a glutathione-s-transferase (GST)-tagged hHO-1 construct. Although the procedure permitted the generation of a full-length HO-1, this form was contaminated with a 30 kDa degradation product that could not be eliminated. Therefore, attempts were made to remove a putative secondary thrombin cleavage site by a conservative mutation of amino acid 254, which replaces arginine with lysine. This mutation allowed the expression and purification of a full-length hHO-1 protein. Unlike wild type (WT) HO-1, the R254K mutant could be purified to a single 32 kDa protein capable of degrading heme at the same rate as the WT enzyme. The R254K full-length form had a specific activity of approximately 200-225 nmol of bilirubin h-1 nmol-1 HO-1 as compared to approximately 140-150 nmol of bilirubin h-1 nmol-1 for the WT form, which contains the 30 kDa contaminant. This is a 2-3-fold increase from the previously reported soluble 30 kDa HO-1, suggesting that the C-terminal 23 amino acids are essential for maximal catalytic activity. Because the membrane-spanning domain is present, the full-length hHO-1 has the potential to incorporate into phospholipid membranes, which can be reconstituted at known concentrations, in combination with other endoplasmic reticulum resident enzymes.

  20. Electromagnetic properties of carbonyl iron and their microwave ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The complex permittivity, permeability and microwave-absorbing properties of rubber composites filled with carbonyl iron are measured at frequencies from 2–18 GHz. The results indicate that the reflection loss peak shifts towards low frequency region with increasing layer thickness or increasing weight concentra-.

  1. Carbonyl Sulfide Isotopologues: Ultraviolet Absorption Cross Sections and Stratospheric Photolysis

    DEFF Research Database (Denmark)

    Danielache, Sebastian Oscar; Nanbu, Shinkoh; Eskebjerg, Carsten

    2009-01-01

    Ultraviolet absorption cross sections of the main and substituted carbonyl sulfide isotopologues were calculated using wavepacket dynamics. The calculated absorption cross section of 16O12C32S is in very good agreement with the accepted experimental spectrum between 190 and 250 nm. Relative to 16O...

  2. Sampling And Analysis Of Carbonyl In Laboratory Atmospheres ...

    African Journals Online (AJOL)

    A sampling and analytical method has been developed for carbonyl concentrations in different laboratory atmospheres at the faculty of Science Bayero University; Kano, Nigeria using cold oximation followed by titrimetric finish. The analysis was carried out between 008 and 1800 hrs from from October 2002 to June 2003.

  3. Cytokinin inhibits the proteasome-mediated degradation of carbonylated proteins in Arabidopsis leaves

    Science.gov (United States)

    Under normal conditions, plants contain numerous carbonylated proteins, which are thought to be indicative of oxidative stress damage. Conditions that promote formation of reactive oxygen species (ROS) enhance protein carbonylation, and protein degradation is required to reverse the damage. However,...

  4. Degradation of carbonyl hydroperoxides in the atmosphere and in combustion

    KAUST Repository

    Xing, Lili

    2017-10-12

    Oxygenates with carbonyl and hydroperoxy functional groups are important intermediates that are generated during the autooxidation of organic compounds in the atmosphere and during the autoignition of transport fuels. In the troposphere, the degradation of carbonyl hydroperoxides leads to low-vapor-pressure polyfunctional species that be taken into in cloud and fog droplets or to the formation of secondary organic aerosols (SOAs). In combustion, the fate of carbonyl hydroperoxides is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the carbonyl hydroperoxides is reac-tion with OH radicals, for which kinetics data are experimentally unavailable. Here, we study 4-hydroperoxy-2-pentanone (CH3C(=O)CH2CH(OOH)CH3) as a model compound to clarify the kinetics of OH reactions with carbonyl hydroperoxides, in par-ticular H-atom abstraction and OH addition reactions. With a combination of electronic structure calculations, we determine previ-ously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunnel-ing (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in atmospheric and combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for the addition reaction are computed using system-specific quantum RRK theory. The calculated temperature range is 298-2400 K, and the pressure range is 0.01–100 atm. The accu-rate thermodynamic and kinetics data determined in this work are indispensable in the global modeling of SOAs in atmospheric science and in the detailed understanding and prediction of ignition properties of hydrocarbons

  5. High-resolution X-ray absorption spectroscopy of iron carbonyl complexes

    OpenAIRE

    Atkins, A.J.; Bauer, M; Jacob, C.R.

    2015-01-01

    We apply high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) to study iron carbonyl complexes. Mono-, bi-, and tri-nuclear carbonyl complexes and pure carbonyl complexes as well as carbonyl complexes containing hydrocarbon ligands are considered. The HERFD-XANES spectra reveal multiple pre-edge peaks with individual signatures for each complex, which could not be detected previously with conventional XANES spectroscopy. These peaks are assigned...

  6. Optimized biotin-hydrazide enrichment and mass spectrometry analysis of peptide carbonyls

    DEFF Research Database (Denmark)

    Havelund, Jesper F.; Wojdyla, K; Jensen, O. N.

    is an important piece of information in this puzzle. Mass spectrometry is here a superior tool; however, protein/peptide carbonylation is of low stoichiometry and the MS signal is decreased due to low ionization efficiency and signal suppression from non-modified peptides. In addition, other more common...... modifications are isobaric to carbonylation and it is often challenging to detect the weaker signal from carbonylated peptides necessitating enrichment step. We here present an optimized method for the enrichment of carbonylated peptides....

  7. Androgen regulation of 5α-reductase isoenzymes in prostate cancer: implications for prostate cancer prevention.

    Directory of Open Access Journals (Sweden)

    Jin Li

    Full Text Available The enzyme 5α-reductase, which converts testosterone to dihydrotestosterone (DHT, performs key functions in the androgen receptor (AR signaling pathway. The three isoenzymes of 5α-reductase identified to date are encoded by different genes: SRD5A1, SRD5A2, and SRD5A3. In this study, we investigated mechanisms underlying androgen regulation of 5α-reductase isoenzyme expression in human prostate cells. We found that androgen regulates the mRNA level of 5α-reductase isoenzymes in a cell type-specific manner, that such regulation occurs at the transcriptional level, and that AR is necessary for this regulation. In addition, our results suggest that AR is recruited to a negative androgen response element (nARE on the promoter of SRD5A3 in vivo and directly binds to the nARE in vitro. The different expression levels of 5α-reductase isoenzymes may confer response or resistance to 5α-reductase inhibitors and thus may have importance in prostate cancer prevention.

  8. Cesium Carbonate-Catalyzed α-Phenylchalcogenation of Carbonyl Compounds with Diphenyl Dichalcogenide

    Directory of Open Access Journals (Sweden)

    Yutaka Nishiyama

    2009-09-01

    Full Text Available It was found that cesium carbonate has a unique catalytic ability on the reaction of carbonyl compounds with diphenyl diselenide to give the corresponding α-phenylseleno carbonyl compounds in moderate to good yields. Similarly, the α-phenylthiolation of carbonyl compounds with diphenyl disulfide was promoted by the cesium carbonate catalyst.

  9. Genetics Home Reference: 5-alpha reductase deficiency

    Science.gov (United States)

    ... G. New mutations, hotspots, and founder effects in Brazilian patients with steroid 5alpha-reductase deficiency type 2. ... should consult with a qualified healthcare professional . About Selection Criteria for Links Data Files & API Site Map ...

  10. Methylenetetrahydrofolate Reductase A1298C Polymorphism and ...

    African Journals Online (AJOL)

    Epigenetic alterations in cancer-related genes are recognized to play an important role in BC carcinogenesis. Epidemiological studies have consistently supported that ... Methylenetetrahydrofolate reductase (MTHFR) enzyme is essential for DNA synthesis ...... disease: A common mutation in methylenetetrahydrofolate.

  11. Methylenetetrahydrofolate Reductase Activity and Folate Metabolism

    Directory of Open Access Journals (Sweden)

    Nursen Keser

    2014-04-01

    Full Text Available Folate is a vital B vitamin which is easily water-soluble. It is a natural source which is found in the herbal and animal foods. Folate has important duties in the human metabolism, one of them is the adjustment of the level of plasma homocysteine. Reduction in MTHFR (methylenetetrahydrofolate reductase,which is in charge of the metabolism of homocysteine activity affects the level of homocysteine. Therefore MTHFR is an important enzyme in folate metabolism. Some of the mutations occurring in the MTHFR gene is a risk factor for various diseases and may be caused the hyperhomocysteinemia or the homocystinuria, and they also may lead to metabolic problems. MTHFR is effective in the important pathways such as DNA synthesis, methylation reactions and synthesis of RNA. C677T and A1298C are the most commonly occurring polymorphisms in the gene of MTHFR. The frequency of these polymorphisms show differences in the populations. MTHFR, folate distribution, metabolism of homocysteine and S-adenosylmethionine, by the MTHFR methylation the genetic defects have the potential of affecting the risk of disease in the negative or positive way.

  12. Proanthocyanidin synthesis in Theobroma cacao: genes encoding anthocyanidin synthase, anthocyanidin reductase, and leucoanthocyanidin reductase.

    Science.gov (United States)

    Liu, Yi; Shi, Zi; Maximova, Siela; Payne, Mark J; Guiltinan, Mark J

    2013-12-05

    The proanthocyanidins (PAs), a subgroup of flavonoids, accumulate to levels of approximately 10% total dry weight of cacao seeds. PAs have been associated with human health benefits and also play important roles in pest and disease defense throughout the plant. To dissect the genetic basis of PA biosynthetic pathway in cacao (Theobroma cacao), we have isolated three genes encoding key PA synthesis enzymes, anthocyanidin synthase (ANS), anthocyanidin reductase (ANR) and leucoanthocyanidin reductase (LAR). We measured the expression levels of TcANR, TcANS and TcLAR and PA content in cacao leaves, flowers, pod exocarp and seeds. In all tissues examined, all three genes were abundantly expressed and well correlated with PA accumulation levels, suggesting their active roles in PA synthesis. Overexpression of TcANR in an Arabidopsis ban mutant complemented the PA deficient phenotype in seeds and resulted in reduced anthocyanidin levels in hypocotyls. Overexpression of TcANS in tobacco resulted in increased content of both anthocyanidins and PAs in flower petals. Overexpression of TcANS in an Arabidopsis ldox mutant complemented its PA deficient phenotype in seeds. Recombinant TcLAR protein converted leucoanthocyanidin to catechin in vitro. Transgenic tobacco overexpressing TcLAR had decreased amounts of anthocyanidins and increased PAs. Overexpressing TcLAR in Arabidopsis ldox mutant also resulted in elevated synthesis of not only catechin but also epicatechin. Our results confirm the in vivo function of cacao ANS and ANR predicted based on sequence homology to previously characterized enzymes from other species. In addition, our results provide a clear functional analysis of a LAR gene in vivo.

  13. Role of Carbonyl Modifications on Aging-Associated Protein Aggregation

    Science.gov (United States)

    Tanase, Maya; Urbanska, Aleksandra M.; Zolla, Valerio; Clement, Cristina C.; Huang, Liling; Morozova, Kateryna; Follo, Carlo; Goldberg, Michael; Roda, Barbara; Reschiglian, Pierluigi; Santambrogio, Laura

    2016-01-01

    Protein aggregation is a common biological phenomenon, observed in different physiological and pathological conditions. Decreased protein solubility and a tendency to aggregate is also observed during physiological aging but the causes are currently unknown. Herein we performed a biophysical separation of aging-related high molecular weight aggregates, isolated from the bone marrow and splenic cells of aging mice and followed by biochemical and mass spectrometric analysis. The analysis indicated that compared to younger mice an increase in protein post-translational carbonylation was observed. The causative role of these modifications in inducing protein misfolding and aggregation was determined by inducing carbonyl stress in young mice, which recapitulated the increased protein aggregation observed in old mice. Altogether our analysis indicates that oxidative stress-related post-translational modifications accumulate in the aging proteome and are responsible for increased protein aggregation and altered cell proteostasis.

  14. Metal Carbonyl-Hydrosilane Reactions and Hydrosilation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Cutler, A. R.

    2001-04-14

    Manganese carbonyl complexes serve as hydrosilation precatalysts for selectively transforming a carbonyl group into a siloxy methylene or a fully reduced methylene group. Substrates of interest include (1) aldehydes, ketones, carboxylic acids, silyl esters, and esters, and (2) their organometallic acyl counterparts. Three relevant catalytic reactions are shown. Two types of manganese precatalysts have been reported: (a) alkyl and acyl complexes (L)(C0){sub 4}MnR [L = CO, PPh{sub 3}; R = COCH{sub 3}, COPh, CH{sub 3}] and (b) halides (CO){sub 5}MnX and [(CO){sub 4}MnX]{sub 2} (X = Br, I). The former promote hydrosilation and deoxygenation catalysis; the latter promote dehydrogenative silation of alcohols and carboxylic acids as well as hydrosilation and deoxygenation of some metallocarboxylic acid derivatives. In every case studied, these Mn precatalysts are far more reactive or selective than traditional Rh(I) precatalysts.

  15. Measurements of carbonyls in a 13-story building.

    Science.gov (United States)

    Báez, Armando P; Padilla, Hugo G; García, Rocío M; Belmont, Raúl D; Torres, Maria del Carmen B

    2004-01-01

    Formaldehyde and acetaldehyde are emitted by many mobile and stationary sources and secondary aldehydes are intermediates in the photo-oxidation of organic compounds in the atmosphere. These aldehydes are emitted indoors by many materials such as furniture, carpets, heating and cooling systems, an by smoking. Carbonyls, mainly formaldehyde and acetaldehyde, have been studied because of their adverse health effects. In addition, formaldehyde is a suspected carcinogen. Therefore, the concentrations of formaldehyde and acetaldehyde were determined to assess the inhalation exposure doses to carbonyls for people who work in a 13-story building and in order to evaluate the cancer hazard. Carbonyl compounds in indoor and outdoor air were measured at a 13-story building located in Mexico City. The mezzanine, fifth and tenth floors, and the third level-parking garage were selected for sampling. Samples were collected in two sampling periods, the first from April 20 to 29, 1998 and the second from December 1 to 20, 1998. Carbonyls were sampled by means of DNHP-coated cartridges at a flow rate of 1 l min(-1) from 9:00 to 19:00 hours, during 2-hour time intervals and analyzed by HPLC with hours, during 2-hour time intervals and analyzed by HPLC with UV/VIS detection. Mean carbonyl concentrations were highest in the 3rd level-parking garage, with the formaldehyde concentration being the highest ranging from 108 to 418 microg m(-3). In working areas, the highest carbonyl arithmetic mean concentrations (AM) were observed on the 5th floor. Acetone and formaldehyde concentrations were highest in April ranging from 161 to 348 microg m(-3) (AM = 226) and from 157 to 270 microg m(-3) (AM = 221), respectively. Propionaldehyde and butyraldehyde were present in smaller concentrations ranging from 2 to 25 and 1 to 28 microg m(-3), respectively, considering all the samples. Mean indoor/outdoor ratios of carbonyls ranged from 1.8 to 9.6. A reduction of inhalation exposure doses of 41% and

  16. Emissions of Toxic Carbonyls in an Electronic Cigarette

    Directory of Open Access Journals (Sweden)

    Guthery William

    2016-01-01

    Full Text Available Electronic cigarettes (e-cigs provide a smoke-free alternative for inhalation of nicotine without the vast array of toxic and carcinogenic combustion products produced by tobacco smoke. Elevated levels of toxic carbonyls may be generated during vaporisation; however, it is unclear whether that is indicative of a fault with the device or is due to the applied conditions of the test. A device, designed and built at this facility, was tested to determine the levels of selected toxic carbonyls. The reservoir was filled with approximately 960 mg of an e-liquid formulation containing 1.8% (w/v nicotine. Devices were puffed 200 times in blocks of 40 using a standardised regime consisting of a 55 mL puff volume; 3 s puff duration; 30 s puff interval; square wave puff profile. Confirmatory testing for nicotine and total aerosol delivery resulted in mean (n = 8 values of 10 mg (RSD 12.3% and 716 mg (RSD 11.2%, respectively. Emissions of toxic carbonyls were highly variable yet were between < 0.1% and 22.9% of expected levels from a Kentucky Reference Cigarette (K3R4F puffed 200 times under Health Canada Intense smoking conditions. It has been shown that a device built to a high specification with relatively consistent nicotine and aerosol delivery emits inconsistent levels of carbonyls. The exposure is greatly reduced when compared with lit tobacco products. However, it was observed that as the reservoirs neared depletion then emission levels were significantly higher

  17. Nucleophilic tetrafluoroethylation of carbonyl compounds with fluorinated sulfones

    Czech Academy of Sciences Publication Activity Database

    Václavík, Jiří; Chernykh, Yana; Jurásek, Bronislav; Beier, Petr

    2015-01-01

    Roč. 169, Jan (2015), s. 24-31 ISSN 0022-1139 R&D Projects: GA ČR GAP207/11/0421 Grant - others:GA MŠk(CZ) ED3.2.00/08.0144; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : fluorine * tetrafluoroethylation * sulfones * nucleophilic addition * carbonyl compounds Subject RIV: CC - Organic Chemistry Impact factor: 2.213, year: 2015

  18. Carbonyl-Phenol Adducts: An Alternative Sink for Reactive and Potentially Toxic Lipid Oxidation Products.

    Science.gov (United States)

    Zamora, Rosario; Hidalgo, Francisco J

    2018-02-14

    Different from the well-characterized function of phenolics as antioxidants, their function as lipid-derived carbonyl scavengers is mostly unknown. However, phenolics react with lipid-derived carbonyls as a function of the nucleophilicity of their reactive groups and the electronic effects and steric hindrances present in the reactive carbonyls. Furthermore, the reaction produces a wide variety of carbonyl-phenol adducts, some of which are stable and have been isolated and characterized but others polymerize spontaneously. This perspective updates present knowledge about the lipid-derived carbonyl trapping ability of phenolics, its competition with carbonyl-amine reactions produced in foods, and the presence of carbonyl-phenol adducts in food products.

  19. Structures of trihydroxynaphthalene reductase-fungicide complexes: implications for structure-based design and catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Liao, D.-I.; Basarab, G.S.; Gatenby, A.A.; Valent, B.; Jordan, D.B. (DuPont)

    2010-03-08

    Trihydroxynaphthalene reductase catalyzes two intermediate steps in the fungal melanin biosynthetic pathway. The enzyme, a typical short-chain dehydrogenase, is the biochemical target of three commercial fungicides. The fungicides bind preferentially to the NADPH form of the enzyme. Three X-ray structures of the Magnaporthe grisea enzyme complexed with NADPH and two commercial and one experimental fungicide were determined at 1.7 {angstrom} (pyroquilon), 2.0 {angstrom} (2,3-dihydro-4-nitro-1H-inden-1-one, 1), and 2.1 {angstrom} (phthalide) resolutions. The chemically distinct inhibitors occupy similar space within the enzyme's active site. The three inhibitors share hydrogen bonds with the side chain hydroxyls of Ser-164 and Tyr-178 via a carbonyl oxygen (pyroquilon and 1) or via a carbonyl oxygen and a ring oxygen (phthalide). Active site residues occupy similar positions among the three structures. A buried water molecule that is hydrogen bonded to the NZ nitrogen of Lys-182 in each of the three structures likely serves to stabilize the cationic form of the residue for participation in catalysis. The pro S hydrogen of NADPH (which is transferred as a hydride to the enzyme's naphthol substrates) is directed toward the carbonyl carbon of the inhibitors that mimic an intermediate along the reaction coordinate. Modeling tetrahydroxynaphthalene and trihydroxynaphthalene in the active site shows steric and electrostatic repulsion between the extra hydroxyl oxygen of the former substrate and the sulfur atom of Met-283 (the C-terminal residue), which accounts, in part, for the 4-fold greater substrate specificity for trihydroxynaphthalene over tetrahydroxynaphthalene.

  20. Iron(III)-catalysed carbonyl-olefin metathesis

    Science.gov (United States)

    Ludwig, Jacob R.; Zimmerman, Paul M.; Gianino, Joseph B.; Schindler, Corinna S.

    2016-05-01

    The olefin metathesis reaction of two unsaturated substrates is one of the most powerful carbon-carbon-bond-forming reactions in organic chemistry. Specifically, the catalytic olefin metathesis reaction has led to profound developments in the synthesis of molecules relevant to the petroleum, materials, agricultural and pharmaceutical industries. These reactions are characterized by their use of discrete metal alkylidene catalysts that operate via a well-established mechanism. While the corresponding carbonyl-olefin metathesis reaction can also be used to construct carbon-carbon bonds, currently available methods are scarce and severely hampered by either harsh reaction conditions or the required use of stoichiometric transition metals as reagents. To date, no general protocol for catalytic carbonyl-olefin metathesis has been reported. Here we demonstrate a catalytic carbonyl-olefin ring-closing metathesis reaction that uses iron, an Earth-abundant and environmentally benign transition metal, as a catalyst. This transformation accommodates a variety of substrates and is distinguished by its operational simplicity, mild reaction conditions, high functional-group tolerance, and amenability to gram-scale synthesis. We anticipate that these characteristics, coupled with the efficiency of this reaction, will allow for further advances in areas that have historically been enhanced by olefin metathesis.

  1. Fluorimetric screening assay for protein carbonyl evaluation in biological samples.

    Science.gov (United States)

    Stocker, P; Ricquebourg, E; Vidal, N; Villard, C; Lafitte, D; Sellami, L; Pietri, S

    2015-08-01

    Many assays are available for the detection of protein carbonyls (PCs). Currently, the measurement of PC groups after their derivatization with 2,4-dinitrophenol hydrazine (DNPH) is widely used for measuring protein oxidation in biological samples. However, this method includes several washing steps. In this context, we have developed a rapid, sensitive, and accurate fluorimetric method adapted to 96-well microplates for the convenient assessment of protein carbonyl level in biological samples. The method reported here is based on the reaction of carbonyl content in proteins with 7-hydrazino-4-nitrobenzo-2,1,3-oxadiazole (NBDH) to form highly fluorescent derivatives via hydrazone formation. PCs were determined using the DNPH and NBDH assays in fully reduced bovine serum albumin (BSA) and plasma and liver homogenates obtained from healthy control rats up the addition of various amounts of HOCl-oxidized BSA (OxBSA). Using the NBDH assay, PC concentrations as low as 0.2 nmol/mg were detected with precision as low as 5%. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy was used to successfully identify the formation of the NBDH adducts after derivatization with standard oxidized peptides. Finally, the two methods were further used for PC determination in plasma and liver samples from diabetic and normal rats, showing that the NBDH assay can be reliably used in biological experiments. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Carbonylation of Ethene Catalysed by Pd(II-Phosphine Complexes

    Directory of Open Access Journals (Sweden)

    Gianni Cavinato

    2014-09-01

    Full Text Available This review deals with olefin carbonylation catalysed by Pd(II-phosphine complexes in protic solvents. In particular, the results obtained in the carbonylation with ethene are reviewed. After a short description of the basic concepts relevant to this catalysis, the review treats in greater details the influence of the bite angle, skeletal rigidity, electronic and steric bulk properties of the ligand on the formation of the products, which range from high molecular weight perfectly alternating polyketones to methyl propanoate. It is shown that the steric bulk plays a major role in directing the selectivity. Particular emphasis is given to the factors governing the very active and selective catalysis to methyl propanoate, including the mechanism of the catalytic cycles with diphosphine- and monophosphine-catalysts. A brief note on the synthesis of methyl propanoate using a “Lucite” type catalyst in ionic liquids is also illustrated. A chapter is dedicated to the carbonylation of olefins in aqueous reaction media. The nonalternating CO-ethene copolymerization is also treated.

  3. Study of the formation of carbonyl compounds in edible oils and fats by 1H-NMR and FTIR

    Science.gov (United States)

    Moya Moreno, M. C. M.; Mendoza Olivares, D.; Amézquita López, F. J.; Peris Martínez, V.; Bosch Reig, F.

    1999-05-01

    Oils and fats start decomposing from the moment they are isolated from their natural environment. Heating accelerates oxidative rancidity and frying at high temperatures produces thermal degradation with the formation of decomposition products, such as aldehydes, ketones, free acids and hydroxilic compounds that in high levels can be harmful to human health. The decomposition products formed up to 300°C were determined by means of 1H-NMR spectroscopy and an FTIR spectroscopic method was developed for the quantification of carbonyl compounds generated during heating. The results show that there is a formation of carbonyl compounds starting at 150°C and when the sample was heated at 300°C for 40 min, the following contents (expressed as butyraldehyde mass fraction) were found: olive oil 10.5%, sunflower oil 11.3%, corn oil 3.0%, seeds oil (sunflower, safflower and canola seed) 6.6% and lard 3.5%.

  4. Characterization of the quinine reductase activity of the ferrice reductase B protein from Paracoccus denitrificans.

    NARCIS (Netherlands)

    Sedlacek, V.; van Spanning, R.J.M.; Kucera, I.

    2009-01-01

    The ferric reductase B (FerB) protein of Paracoccus denitrificans exhibits activity of an NAD(P)H: Fe(III) chelate, chromate and quinone oxidoreductase. Sequence analysis places FerB in a family of soluble flavin-containing quinone reductases. The enzyme reduces a range of quinone substrates,

  5. A High Resolution/Accurate Mass (HRAM) Data-Dependent MS3 Neutral Loss Screening, Classification, and Relative Quantitation Methodology for Carbonyl Compounds in Saliva

    Science.gov (United States)

    Dator, Romel; Carrà, Andrea; Maertens, Laura; Guidolin, Valeria; Villalta, Peter W.; Balbo, Silvia

    2017-04-01

    Reactive carbonyl compounds (RCCs) are ubiquitous in the environment and are generated endogenously as a result of various physiological and pathological processes. These compounds can react with biological molecules inducing deleterious processes believed to be at the basis of their toxic effects. Several of these compounds are implicated in neurotoxic processes, aging disorders, and cancer. Therefore, a method characterizing exposures to these chemicals will provide insights into how they may influence overall health and contribute to disease pathogenesis. Here, we have developed a high resolution accurate mass (HRAM) screening strategy allowing simultaneous identification and relative quantitation of DNPH-derivatized carbonyls in human biological fluids. The screening strategy involves the diagnostic neutral loss of hydroxyl radical triggering MS3 fragmentation, which is only observed in positive ionization mode of DNPH-derivatized carbonyls. Unique fragmentation pathways were used to develop a classification scheme for characterizing known and unanticipated/unknown carbonyl compounds present in saliva. Furthermore, a relative quantitation strategy was implemented to assess variations in the levels of carbonyl compounds before and after exposure using deuterated d 3 -DNPH. This relative quantitation method was tested on human samples before and after exposure to specific amounts of alcohol. The nano-electrospray ionization (nano-ESI) in positive mode afforded excellent sensitivity with detection limits on-column in the high-attomole levels. To the best of our knowledge, this is the first report of a method using HRAM neutral loss screening of carbonyl compounds. In addition, the method allows simultaneous characterization and relative quantitation of DNPH-derivatized compounds using nano-ESI in positive mode.

  6. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C, 15N-labeled peptides and proteins

    Science.gov (United States)

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly 13C, 15N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22 kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600 MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i - 2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed.

  7. Inhibition of aldose reductase activity by Cannabis sativa chemotypes extracts with high content of cannabidiol or cannabigerol.

    Science.gov (United States)

    Smeriglio, Antonella; Giofrè, Salvatore V; Galati, Enza M; Monforte, Maria T; Cicero, Nicola; D'Angelo, Valeria; Grassi, Gianpaolo; Circosta, Clara

    2018-02-07

    Aldose reductase (ALR2) is a key enzyme involved in diabetic complications and the search for new aldose reductase inhibitors (ARIs) is currently very important. The synthetic ARIs are often associated with deleterious side effects and medicinal and edible plants, containing compounds with aldose reductase inhibitory activity, could be useful for prevention and therapy of diabetic complications. Non-psychotropic phytocannabinoids exert multiple pharmacological effects with therapeutic potential in many diseases such as inflammation, cancer, diabetes. Here, we have investigated the inhibitory effects of extracts and their fractions from two Cannabis sativa L. chemotypes with high content of cannabidiol (CBD)/cannabidiolic acid (CBDA) and cannabigerol (CBG)/cannabigerolic acid (CBGA), respectively, on human recombinant and pig kidney aldose reductase activity in vitro. A molecular docking study was performed to evaluate the interaction of these cannabinoids with the active site of ALR2 compared to known ARIs. The extracts showed significant dose-dependent aldose reductase inhibitory activity (>70%) and higher than fractions. The inhibitory activity of the fractions was greater for acidic cannabinoid-rich fractions. Comparative molecular docking results have shown a higher stability of the ALR2-cannabinoid acids complex than the other inhibitors. The extracts of Cannabis with high content of non-psychotropic cannabinoids CBD/CBDA or CBG/CBGA significantly inhibit aldose reductase activity. These results may have some relevance for the possible use of C. sativa chemotypes based preparations as aldose reductase inhibitors. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method.

    Science.gov (United States)

    Black, Stuart; Ferrell, Jack R

    2017-02-07

    Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls cause an increase in viscosity (often referred to as 'aging') during storage of bio-oils. As such, carbonyl content has previously been used as a method of tracking bio-oil aging and condensation reactions with less variability than viscosity measurements. Additionally, carbonyls are also responsible for coke formation in bio-oil upgrading processes. Given the importance of carbonyls in bio-oils, accurate analytical methods for their quantification are very important for the bio-oil community. Potentiometric titration methods based on carbonyl oximation have long been used for the determination of carbonyl content in pyrolysis bio-oils. Here, we present a modification of the traditional carbonyl oximation procedures that results in less reaction time, smaller sample size, higher precision, and more accurate carbonyl determinations. While traditional carbonyl oximation methods occur at room temperature, the Faix method presented here occurs at an elevated temperature of 80 °C.

  9. [Chemical Characteristics and Sources of Atmospheric Carbonyls During the 2014 Beijing APEC].

    Science.gov (United States)

    He, Xiao-lang; Tan, Ji-hua; Guo, Song-jun; Ma, Yong-liang; He, Ke-bin

    2016-03-15

    Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM₂.₅ during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC.

  10. 5{alpha}-reductase expression by prostate cancer cell lines and benign prostatic hyperplasia in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C.M.; Masters, J.R.W. [Univ. College of London (United Kingdom)]|[Pfizer Central Research, Kent (United Kingdom); Ballard, S.A.; Worman, N. [Pfizer Central Research, Sandwich (United Kingdom)

    1996-04-01

    5{alpha}-Reductase (5{alpha}R) activity in two human prostate cancer cell lines was compared to that in benign prostatic hyperplasia (BPH) tissue and COS cells transfected with and expressing the human genes for 5{alpha}-reductase type 1 (5{alpha}R1) and type 2 (5{alpha}R2). Comparisons were based on pH profiles and sensitivities to selective inhibitors of 5{alpha}-reductase. In the cancer lines, activity was greatest over the pH range 7-8, compared to a sharp peak of activity between pH 5-5.5 in BPH tissue and COS cells expressing 5{alpha}R2. Finasteride and SKF105,657 were potent inhibitors of 5{alpha}-reductase activity in BPH tissue and COS cells expressing 5{alpha}R2, but weak inhibitors in the cancer lines and in COS cells expressing 5{alpha}R1. In contrast, LTK1 17,026 was a more potent inhibitor of 5{alpha}-reductase activity in the prostate cancer cell lines and in COS cells expressing 5{alpha}R1. These data indicate that human prostate cancer cell lines express 5{alpha}-reductase activity similar to that in COS cells transfected with 5{alpha}R1, but different from that in BPH tissue. This may be a consequence of in vitro culture. Alternatively, it may reflect a change occurring as a result of neoplastic transformation, in which case it will be important to select appropriate inhibitors in the clinic. 29 refs., 3 figs., 2 tabs.

  11. Respiratory arsenate reductase as a bidirectional enzyme

    Science.gov (United States)

    Richey, C.; Chovanec, P.; Hoeft, S.E.; Oremland, R.S.; Basu, P.; Stolz, J.F.

    2009-01-01

    The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative respiratory arsenate reductase (Arr). Here we show that one homolog is expressed under chemolithoautotrophic conditions and exhibits both arsenite oxidase and arsenate reductase activity. We also demonstrate that Arr from two arsenate respiring bacteria, Alkaliphilus oremlandii and Shewanella sp. strain ANA-3, is also biochemically reversible. Thus Arr can function as a reductase or oxidase. Its physiological role in a specific organism, however, may depend on the electron potentials of the molybdenum center and [Fe–S] clusters, additional subunits, or constitution of the electron transfer chain. This versatility further underscores the ubiquity and antiquity of microbial arsenic metabolism.

  12. Crystallization and preliminary X-ray diffraction studies of ferredoxin reductase from Leptospira interrogans

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Alessandro S.; Ferrarezi, Thiago [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil); Catalano-Dupuy, Daniela L.; Ceccarelli, Eduardo A. [Facultad de Ciencias Bioquímicas y Farmacéuticas, Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario (Argentina); Polikarpov, Igor, E-mail: ipolikarpov@if.sc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador Saocarlense 400, São Carlos, SP, 13560-970 (Brazil)

    2006-07-01

    Crystals adequate for X-ray diffraction analysis have been prepared from L. interrogans ferredoxin-NADP{sup +} reductase. Ferredoxin-NADP{sup +} reductase (FNR) is an FAD-containing enzyme that catalyzes electron transfer between NADP(H) and ferredoxin. Here, results are reported of the recombinant expression, purification and crystallization of FNR from Leptospira interrogans, a parasitic bacterium of animals and humans. The L. interrogans FNR crystals belong to a primitive monoclinic space group and diffract to 2.4 Å resolution at a synchrotron source.

  13. The 5,10-methylenetetrahydrofolate reductase C677T polymorphism interacts with smoking to increase homocysteine.

    NARCIS (Netherlands)

    Brown, K.S.; Kluijtmans, L.A.J.; Young, I.S.; Murray, L.; McMaster, D.; Woodside, J.; Yarnell, J.W.; Boreham, C.A.; McNulty, H.; Strain, J.J.; McPartlin, J.; Scott, J.M.; Mitchell, L.E.; Whitehead, A.S.

    2004-01-01

    Elevated homocysteine is a risk marker for several human pathologies. Risk factors for elevated homocysteine include low folate and homozygosity for the T allele of the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism. Because nitric oxide may inhibit folate catabolism and

  14. Biliverdin Reductase inhibitors did not improve severe unconjugated hyperbilirubinemia in vivo

    NARCIS (Netherlands)

    van Dijk, Remco; Aronson, Sem J.; de Waart, Dirk R.; van de Graaf, Stan F.; Duijst, Suzanne; Seppen, Jurgen; Oude Elferink, Ronald; Beuers, Ulrich; Bosma, Piter J.

    2017-01-01

    We aimed to identify potent biliverdin reductase (BVRA) inhibitors as a novel concept for the treatment of severe unconjugated hyperbilirubinemia. 1280 FDA-approved compounds were screened in vitro for their ability to inhibit human and rat BVRA activity and 26 compounds were identified as BVRA

  15. Carbonyl Compounds Produced by Vaporizing Cannabis Oil Thinning Agents.

    Science.gov (United States)

    Troutt, William D; DiDonato, Matthew D

    2017-11-01

    Cannabis use has increased in the United States, particularly the use of vaporized cannabis oil, which is often mixed with thinning agents for use in vaporizing devices. E-cigarette research shows that heated thinning agents produce potentially harmful carbonyls; however, similar studies have not been conducted (1) with agents that are commonly used in the cannabis industry and (2) at temperatures that are appropriate for cannabis oil vaporization. The goal of this study was to determine whether thinning agents used in the cannabis industry produce potentially harmful carbonyls when heated to a temperature that is appropriate for cannabis oil vaporization. Four thinning agents (propylene glycol [PG], vegetable glycerin [VG], polyethylene glycol 400 [PEG 400], and medium chain triglycerides [MCT]) were heated to 230°C and the resulting vapors were tested for acetaldehyde, acrolein, and formaldehyde. Each agent was tested three times. Testing was conducted in a smoking laboratory. Carbonyl levels were measured in micrograms per puff block. Analyses showed that PEG 400 produced significantly higher levels of acetaldehyde and formaldehyde than PG, MCT, and VG. Formaldehyde production was also significantly greater in PG compared with MCT and VG. Acrolein production did not differ significantly across the agents. PG and PEG 400 produced high levels of acetaldehyde and formaldehyde when heated to 230°C. Formaldehyde production from PEG 400 isolate was particularly high, with one inhalation accounting for 1.12% of the daily exposure limit, nearly the same exposure as smoking one cigarette. Because PG and PEG 400 are often mixed with cannabis oil, individuals who vaporize cannabis oil products may risk exposure to harmful formaldehyde levels. Although more research is needed, consumers and policy makers should consider these potential health effects before use and when drafting cannabis-related legislation.

  16. Crystallization and preliminary X-ray diffraction analysis of maize aldose reductase

    Energy Technology Data Exchange (ETDEWEB)

    Kiyota, Eduardo [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil); Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas-SP (Brazil); Sousa, Sylvia Morais de [Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas, Campinas-SP (Brazil); Santos, Marcelo Leite dos; Costa Lima, Aline da [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil); Menossi, Marcelo [Departamento de Genética e Evolução, Instituto de Biologia, Universidade Estadual de Campinas, Campinas-SP (Brazil); Yunes, José Andrés [Laboratório de Biologia Molecular, Centro Infantil Boldrini, Campinas-SP (Brazil); Aparicio, Ricardo, E-mail: aparicio@iqm.unicamp.br [Laboratório de Biologia Estrutural, Instituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas-SP (Brazil)

    2007-11-01

    Preliminary X-ray diffraction studies of apo maize aldose reductase at 2.0 Å resolution are reported. Maize aldose reductase (AR) is a member of the aldo-keto reductase superfamily. In contrast to human AR, maize AR seems to prefer the conversion of sorbitol into glucose. The apoenzyme was crystallized in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 47.2, b = 54.5, c = 100.6 Å and one molecule in the asymmetric unit. Synchrotron X-ray diffraction data were collected and a final resolution limit of 2.0 Å was obtained after data reduction. Phasing was carried out by an automated molecular-replacement procedure and structural refinement is currently in progress. The refined structure is expected to shed light on the functional/enzymatic mechanism and the unusual activities of maize AR.

  17. Aldose reductase is involved in long-term adaptation of EUE cells to hyperosmotic stress.

    Science.gov (United States)

    Ferraretto, A; Negri, A; Giuliani, A; De Grada, L; Fuhrman Conti, A M; Ronchi, S

    1993-02-17

    Aldose reductase has been shown to be expressed in large amount by human embryonic epithelial cells (EUE) in response to osmotic stress. This conclusion is the result of studies undertaken following the purification to homogeneity of two forms of a 35-kDa protein overexpressed in EUE cells grown in hypertonic saline culture medium as compared to EUE cells grown in isoosmotic medium. Amino-acid composition, molecular weight and partial internal amino-acid sequence showed that the above proteins are two different forms of aldose reductase. These findings were confirmed by the observation that aldose reductase activity increased about 150-fold in adapted cells and returned to basal levels in de-adapted cells.

  18. Nanostructure Fabrication by Electron-Beam-Induced Deposition with Metal Carbonyl Precursor and Water Vapor

    Science.gov (United States)

    Takeguchi, Masaki; Shimojo, Masayuki; Furuya, Kazuo

    2007-09-01

    Nanorod fabrication is performed by electron beam induced deposition (EBID) with iron carbonyl [Fe(CO)5] and tungsten carbonyl [W(CO)6] precursors. The effects of water vapor addition to each metal carbonyl on the microstructure and composition of the obtained nanorods are studied. Normally, EBID-fabricated metal nanorods consist of an amorphous phase containing a considerable amount of carbon. However, it is found that water vapor addition to iron carbonyl can effectively reduce the carbon content of the nanorods and induce the formation of carbon-free crystalline Fe3O4 nanorods with increasing partial pressure ratio of water vapor to iron carbonyl. In contrast, for tungsten carbonyl, water vapor addition has no obvious effect on carbon content reduction. The obtained nanorods consist of a carbon-rich amorphous matrix containing tungsten oxide nanocrystals inside.

  19. Frustrated Lewis pairs-assisted reduction of carbonyl compounds

    DEFF Research Database (Denmark)

    Marek, Ales; Pedersen, Martin Holst Friborg

    2015-01-01

    An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, absolute regioselectivity and the non-metallic character of the reagent, it provides an excellent tool...... for H-1, H-2 as well as H-3 chemistry. It is a new strategy for the one-pot synthesis of aromatic alcohols selectively labeled with heavy isotopes of hydrogen. © 2015 Elsevier Ltd. All rights reserved....

  20. Characterization of the chlorate reductase from Pseudomonas chloritidismutans

    NARCIS (Netherlands)

    Wolterink, A.F.W.M.; Schiltz, E.; Hagedoorn, P.L.; Hagen, W.R.; Kengen, S.W.M.; Stams, A.J.M.

    2003-01-01

    A chlorate reductase has been purified from the chlorate-reducing strain Pseudomonas chloritidismutans. Comparison with the periplasmic (per)chlorate reductase of strain GR-1 showed that the cytoplasmic chlorate reductase of P. chloritidismutans reduced only chlorate and bromate. Differences were

  1. 21 CFR 864.7375 - Glutathione reductase assay.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Glutathione reductase assay. 864.7375 Section 864...) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7375 Glutathione reductase assay. (a) Identification. A glutathione reductase assay is a device used to determine the...

  2. Methylenetetrahydrofolate reductase gene polymorphism in type 1 ...

    African Journals Online (AJOL)

    In patients with type-I diabetes mellitus folate deficiency is associated with endothelial dysfunction. So, polymorphism in genes involved in folate metabolism may have a role in vascular disease. This study was designed to evaluate the relationship between methylenetetrahydrofolate reductase (MTHFR) gene polymorphism ...

  3. Methylenetetrahydrofolate reductase A1298C polymorphism and ...

    African Journals Online (AJOL)

    Methylenetetrahydrofolate reductase A1298C polymorphism and breast cancer risk: A meta analysis of 33 studies. ... were searched for case‑control studies relating the association between MTHFR A1298C polymorphism and BC risk and estimated summary odds ratios (ORs) with confidence intervals (CIs) for assessment.

  4. Differential nitrate accumulation, nitrate reduction, nitrate reductase ...

    African Journals Online (AJOL)

    Differential nitrate accumulation, nitrate reduction, nitrate reductase activity, protein production and carbohydrate biosynthesis in response to potassium and sodium ... due to the positive effects of potassium on the enzyme activity, sugars transport, water and nutrient transport, protein synthesis and carbohydrate metabolism.

  5. Two Greek siblings with sepiapterin reductase deficiency.

    NARCIS (Netherlands)

    Verbeek, M.M.; Willemsen, M.A.A.P.; Wevers, R.A.; Lagerwerf, A.J.; Abeling, N.G.; Blau, N.; Thony, B.; Vargiami, E.; Zafeiriou, D.I.

    2008-01-01

    BACKGROUND: Sepiapterin reductase (SR) deficiency is a rare inherited disorder of neurotransmitter metabolism; less than 25 cases have been described in the literature so far. METHODS: We describe the clinical history and extensive cerebrospinal fluid (CSF) and urine examination of two Greek

  6. Xylose reductase from the thermophilic fungus Talaromyces ...

    Indian Academy of Sciences (India)

    Given the potential application of xylose reductase enzymes that preferentially utilize the reduced form of nicotinamide adenine dinucleotide (NADH) rather than NADPH in the fermentation of five carbon sugars by genetically engineered microorganisms, the coenzyme selectivity of TeXR was altered by site-directed ...

  7. Clipboard: Lymphohematopoietic licence: Sterol C-14 reductase ...

    Indian Academy of Sciences (India)

    Clipboard: Lymphohematopoietic licence: Sterol C-14 reductase activity of lamin B receptor (Lbr) is essential for neutrophil differentiation. Durgadas P Kasbekar. Volume 37 ... Keywords. Greenberg/HEM dysplasia; lymphohematopoietic progenitor cells; nuclear envelope; Pelger-Huët anomaly; promyelocyte differentiation ...

  8. Methylenetetrahydrofolate reductase gene polymorphism in type 1 ...

    African Journals Online (AJOL)

    Mohammed A AboElAsrar

    2012-05-05

    May 5, 2012 ... Elevated homocysteine is a known risk factor for vascular disease. So the polymorphism in methylenetetrahydrofolate reductase may have detrimental consequences [5]. In patients with type-I diabetes mellitus folate deficiency is associated with endothelial dysfunction and folate supplementa- tion improves ...

  9. Transition-metal-catalyzed carbonylation reactions of olefins and alkynes: a personal account.

    Science.gov (United States)

    Wu, Xiao-Feng; Fang, Xianjie; Wu, Lipeng; Jackstell, Ralf; Neumann, Helfried; Beller, Matthias

    2014-04-15

    Carbon monoxide was discovered and identified in the 18th century. Since the first applications in industry 80 years ago, academic and industrial laboratories have broadly explored CO's use in chemical reactions. Today organic chemists routinely employ CO in organic chemistry to synthesize all kinds of carbonyl compounds. Despite all these achievements and a century of carbonylation catalysis, many important research questions and challenges remain. Notably, apart from academic developments, industry applies carbonylation reactions with CO on bulk scale. In fact, today the largest applications of homogeneous catalysis (regarding scale) are carbonylation reactions, especially hydroformylations. In addition, the vast majority of acetic acid is produced via carbonylation of methanol (Monsanto or Cativa process). The carbonylation of olefins/alkynes with nucleophiles, such as alcohols and amines, represent another important type of such reactions. In this Account, we discuss our work on various carbonylations of unsaturated compounds and related reactions. Rhodium-catalyzed isomerization and hydroformylation reactions of internal olefins provide straightforward access to higher value aldehydes. Catalytic hydroaminomethylations offer an ideal way to synthesize substituted amines and even heterocycles directly. More recently, our group has also developed so-called alternative metal catalysts based on iridium, ruthenium, and iron. What about the future of carbonylation reactions? CO is already one of the most versatile C1 building blocks for organic synthesis and is widely used in industry. However, because of CO's high toxicity and gaseous nature, organic chemists are often reluctant to apply carbonylations more frequently. In addition, new regulations have recently made the transportation of carbon monoxide more difficult. Hence, researchers will need to develop and more frequently use practical and benign CO-generating reagents. Apart from formates, alcohols, and metal

  10. Inhibition of NADPH cytochrome P450 reductase by the model sulfur mustard vesicant 2-chloroethyl ethyl sulfide is associated with increased production of reactive oxygen species.

    Science.gov (United States)

    Gray, Joshua P; Mishin, Vladimir; Heck, Diane E; Laskin, Debra L; Laskin, Jeffrey D

    2010-09-01

    Inhalation of vesicants including sulfur mustard can cause significant damage to the upper airways. This is the result of vesicant-induced modifications of proteins important in maintaining the integrity of the lung. Cytochrome P450s are the major enzymes in the lung mediating detoxification of sulfur mustard and its metabolites. NADPH cytochrome P450 reductase is a flavin-containing electron donor for cytochrome P450. The present studies demonstrate that the sulfur mustard analog, 2-chloroethyl ethyl sulfide (CEES), is a potent inhibitor of human recombinant cytochrome P450 reductase, as well as native cytochrome P450 reductase from liver microsomes of saline and beta-naphthoflavone-treated rats, and cytochrome P450 reductase from type II lung epithelial cells. Using rat liver microsomes from beta-naphthoflavone-treated rats, CEES was found to inhibit CYP 1A1 activity. This inhibition was overcome by microsomal cytochrome P450 reductase from saline-treated rats, which lack CYP 1A1 activity, demonstrating that the CEES inhibitory activity was selective for cytochrome P450 reductase. Cytochrome P450 reductase also generates reactive oxygen species (ROS) via oxidation of NADPH. In contrast to its inhibitory effects on the reduction of cytochrome c and CYP1A1 activity, CEES was found to stimulate ROS formation. Taken together, these data demonstrate that sulfur mustard vesicants target cytochrome P450 reductase and that this effect may be an important mechanism mediating oxidative stress and lung injury. 2010. Published by Elsevier Inc.

  11. Associations between two common variants C677T and A1298C in the methylenetetrahydrofolate reductase gene and measures of folate metabolism and DNA stability (strand breaks, misincorporated uracil, and DNA methylation status) in human lymphocytes in vivo.

    Science.gov (United States)

    Narayanan, Sabrina; McConnell, Josie; Little, Julian; Sharp, Linda; Piyathilake, Chandrika J; Powers, Hilary; Basten, Graham; Duthie, Susan J

    2004-09-01

    Homozygosity for variants of the methylenetetrahydrofolate reductase (MTHFR) gene is associated with decreased risk for colorectal cancer. We have investigated the relationships between two variants of the MTHFR gene (C677T and A1298C) and blood folate, homocysteine, and genomic stability (strand breakage, misincorporated uracil, and global cytosine methylation in lymphocytes) in a study of 199 subjects. The frequencies of homozygosity for the C677T and A1298C variants of the MTHFR gene were 12.6% and 14.6%, respectively. Plasma homocysteine, folate, vitamin B12, 5-methyltetrahydrofolate, and RBC folate were determined in the C677T genotypes. Plasma folate was significantly lower (P A1298C variant did not influence plasma homocysteine, folate, 5-methyltetrahydrofolate, vitamin B12, or RBC folate. Lymphocyte DNA stability biomarkers (strand breaks, misincorporated uracil, and global DNA methylation) were similar for all MTHFR C677T or A1298C variants. Data from this study do not support the hypothesis that polymorphisms in the MTHFR gene increase DNA stability by sequestering 5,10-methylenetetrahydrofolate for thymidine synthesis and reducing uracil misincorporation into DNA.

  12. Iron(III)-Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    Saá, Carlos

    2016-09-05

    Recent developments in catalytic carbonyl-olefin metathesis are summarized in this Highlight. Schindler and co-workers have reported that the environmentally benign FeCl3 catalyst promotes ring-closing carbonyl-olefin metathesis (RCCOM) in high yield under very mild conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite

    DEFF Research Database (Denmark)

    Rasmussen, Dominik Bjørn; Christensen, Jakob Munkholt; Temel, Burcin

    2015-01-01

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated ...... acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction....

  14. VizieR Online Data Catalog: Millimeter wave spectra of carbonyl cyanide (Bteich+, 2016)

    Science.gov (United States)

    Bteich, S. B.; Tercero, B.; Cernicharo, J.; Motiyenko, R. A.; Margules, L.; Guillemin, J.-C.

    2016-05-01

    Table 3 contains assigned rotational transitions of the ground state and the first excited vibrational state (v5=1) of carbonyl cyanide. Table 4 contains predicted transitions of the ground vibrational state of carbonyl cyanide in the frequency range up to 1THz. (2 data files).

  15. Steroid 5alpha-reductase inhibitors.

    Science.gov (United States)

    Flores, Eugenio; Bratoeff, Eugene; Cabeza, Marisa; Ramirez, Elena; Quiroz, Alexandra; Heuze, Ivonne

    2003-05-01

    The objective of this study is to synthesize new steroidal compounds based on the progesterone skeleton with a high inhibitory activity for the enzyme 5alpha-reductase. Presently similar compounds are being used for the treatment of androgen dependent diseases such as: hirsutism, androgenic alopecia, bening prostatic hyperplasia and prostate cancer. Dihydrotestosterone 2 (Fig. (1)), a 5alpha-reduced metabolite of testosterone 1 has been implicated as a causative factor in the progression of these diseases, largely through the clinical evaluation of males who are genetically deficient of steroid 5alpha-reductase enzyme. As a result of this study, the inhibition of this enzyme has become a pharmacological strategy for the design and synthesis of new antiandrogenic drugs. The advent of finasteride 8 (Fig. (4)) a 5alpha-reductase inhibitor has grately alleviated the symptoms associated with benign prostatic hyperplasia. In our laboratory we recently synthesized several new 16beta-methyl-pregnadiene-3,20-diones derivatives 27 (Fig.(6)), 38-42 (Fig. (11)), 16beta-phenyl-pregnadiene-3,17a-dione derivatives 32-33 (Fig. (7)), 16beta-phenyl-pregnatriene-3,17a-diones, 30, 31 (Fig. (7)) and 16beta-methyl-pregnatriene-3,20-diones 43-46 (Fig. (11)). These compounds were evaluated as 5alpha-reductase inhibitors in the following biological models: Penicillium crustosum broths, the flank organs of gonadectomized male hamsters, the incorporation of radiolabeled sodium acetate into lipids, the effect of the new steroids on the reduction of the weight of the seminal vesicles and on the in vitro metabolism of [(3)H]T to [(3)H]DHT in seminal vesicles homogenates of gonadectomized male hamsters. All trienones 30, 31, and 43-46 in all biological models showed consistently a higher 5alpha-reductase inhibitory activity than the corresponding dienones 27, 32, 33 and 38-42. We believe that with these compounds the 5alpha-reductase enzyme is inactivated by an irreversible Michael type addition

  16. 5,10-Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTRR), and methionine synthase reductase (MTR) gene polymorphisms and adult meningioma risk.

    Science.gov (United States)

    Zhang, Jun; Zhou, Yan-Wen; Shi, Hua-Ping; Wang, Yan-Zhong; Li, Gui-Ling; Yu, Hai-Tao; Xie, Xin-You

    2013-11-01

    The causes of meningiomas are not well understood. Folate metabolism gene polymorphisms have been shown to be associated with various human cancers. It is still controversial and ambiguous between the functional polymorphisms of folate metabolism genes 5,10-methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTRR), and methionine synthase reductase (MTR) and risk of adult meningioma. A population-based case–control study involving 600 meningioma patients (World Health Organization [WHO] Grade I, 391 cases; WHO Grade II, 167 cases; WHO Grade III, 42 cases) and 600 controls was done for the MTHFR C677T and A1298C, MTRR A66G, and MTR A2756G variants in Chinese Han population. The folate metabolism gene polymorphisms were determined by using a polymerase chain reaction–restriction fragment length polymorphism assay. Meningioma cases had a significantly lower frequency of MTHFR 677 TT genotype [odds ratio (OR) = 0.49, 95 % confidence interval (CI) 0.33–0.74; P = 0.001] and T allele (OR = 0.80, 95 % CI 0.67–0.95; P = 0.01) than controls. A significant association between risk of meningioma and MTRR 66 GG (OR = 1.41, 95 % CI 1.02–1.96; P = 0.04) was also observed. When stratifying by the WHO grade of meningioma, no association was found. Our study suggested that MTHFR C677T and MTRR A66G variants may affect the risk of adult meningioma in Chinese Han population.

  17. High-resolution X-ray absorption spectroscopy of iron carbonyl complexes.

    Science.gov (United States)

    Atkins, Andrew J; Bauer, Matthias; Jacob, Christoph R

    2015-06-07

    We apply high-energy-resolution fluorescence-detected (HERFD) X-ray absorption near-edge spectroscopy (XANES) to study iron carbonyl complexes. Mono-, bi-, and tri-nuclear carbonyl complexes and pure carbonyl complexes as well as carbonyl complexes containing hydrocarbon ligands are considered. The HERFD-XANES spectra reveal multiple pre-edge peaks with individual signatures for each complex, which could not be detected previously with conventional XANES spectroscopy. These peaks are assigned and analysed with the help of TD-DFT calculations. We demonstrate that the pre-edge peaks can be used to distinguish the different types of iron-iron interactions in carbonyl complexes. This opens up new possibilities for applying HERFD-XANES spectroscopy to probe the electronic structure of iron catalysts.

  18. Rapid method for determination of carbonyl groups in lignin compounds by headspace gas chromatography.

    Science.gov (United States)

    Li, Jing; Hu, Hui-Chao; Chai, Xin-Sheng

    2015-07-24

    The paper reports on a novel method for rapid determination of carbonyl in lignins by headspace gas chromatography (HS-GC). The method involves the quantitative carbonyl reduction for aldehydes in 2min at room temperature or for acetones in 30min at 80°C by sodium borohydride solution in a closed headspace sample vial. After the reaction, the solution was acidified by injecting sulfuric acid solution and the hydrogen released to the headspace was determined by GC using thermal-conductivity detector. The results showed that with the addition of SiO2 powder, the reduction reaction of carbonyl groups can be greatly facilitated. The method has a good measurement precision (RSD<7.74%) and accuracy (relative error <10% compared with a reference method) in the carbonyl quantification. It is suitable to be used for rapid determination of carbonyl content in lignin and related materials. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Protein carbonylation and metal-catalyzed protein oxidation in a cellular perspective

    DEFF Research Database (Denmark)

    Møller, Ian Max; Rogowska-Wrzesinska, Adelina; Rao, Shyama Prasad

    2011-01-01

    Proteins can become oxidatively modified in many different ways, either by direct oxidation of amino acid side chains and protein backbone or indirectly by conjugation with oxidation products of polyunsaturated fatty acids and carbohydrates. While reversible oxidative modifications are thought...... to be relevant in physiological processes, irreversible oxidative modifications are known to contribute to cellular damage and disease. The most well-studied irreversible protein oxidation is carbonylation. In this work we first examine how protein carbonylation occurs via metal-catalyzed oxidation (MCO) in vivo...... and in vitro with an emphasis on cellular metal ion homeostasis and metal binding. We then review proteomic methods currently used for identifying carbonylated proteins and their sites of modification. Finally, we discuss the identified carbonylated proteins and the pattern of carbonylation sites in relation...

  20. Cell signaling promoting protein carbonylation does not cause sulfhydryl oxidation: Implications to the mechanism of redox signaling.

    Science.gov (United States)

    Suzuki, Yuichiro J; Almansour, Faisal; Cucinotta, Camilla; Rybka, Vladyslava; Marcocci, Lucia

    2017-01-01

    Reactive oxygen species (ROS) have been recognized as second messengers, however, targeting mechanisms for ROS in cell signaling have not been defined. While ROS oxidizing protein cysteine thiols has been the most popular proposed mechanism, our laboratory proposed that ligand/receptor-mediated cell signaling involves protein carbonylation. Peroxiredoxin-6 (Prx6) is one protein that is carbonylated at 10 min after the platelet-derived growth factor (PDGF) stimulation of human pulmonary artery smooth muscle cells. In the present study, the SulfoBiotics Protein Redox State Monitoring Kit Plus (Dojindo Molecular Technologies) was used to test if cysteine residues of Prx6 are oxidized in response to the PDGF stimulation. Human Prx6 has a molecular weight of 25 kDa and contains two cysteine residues. The Dojindo system adds the 15 kDa Protein-SHifter if these cysteine residues are reduced in the cells. Results showed that, in untreated cells, the Prx6 molecule predominantly exhibited the 55 kDa band, indicating that both cysteine residues are reduced in the cells. Treatment of cells with 1 mM H 2O 2 caused the disappearance of the 55 kDa band and the appearance of a 40 kDa band, suggesting that the high concentration of H 2O 2 oxidized one of the two cysteine residues in the Prx6 molecule. By contrast, PDGF stimulation had no effects on the thiol status of the Prx6 molecule. We concluded that protein carbonylation is a more sensitive target of ROS during ligand/receptor-mediated cell signaling than sulfhydryl oxidation.

  1. Biliverdin reductase: A major physiologic cytoprotectant

    Science.gov (United States)

    Barañano, David E.; Rao, Mahil; Ferris, Christopher D.; Snyder, Solomon H.

    2002-01-01

    Bilirubin, an abundant pigment that causes jaundice, has long lacked any clear physiologic role. It arises from enzymatic reduction by biliverdin reductase of biliverdin, a product of heme oxygenase activity. Bilirubin is a potent antioxidant that we show can protect cells from a 10,000-fold excess of H2O2. We report that bilirubin is a major physiologic antioxidant cytoprotectant. Thus, cellular depletion of bilirubin by RNA interference markedly augments tissue levels of reactive oxygen species and causes apoptotic cell death. Depletion of glutathione, generally regarded as a physiologic antioxidant cytoprotectant, elicits lesser increases in reactive oxygen species and cell death. The potent physiologic antioxidant actions of bilirubin reflect an amplification cycle whereby bilirubin, acting as an antioxidant, is itself oxidized to biliverdin and then recycled by biliverdin reductase back to bilirubin. This redox cycle may constitute the principal physiologic function of bilirubin. PMID:12456881

  2. Electroless plating preparation and electromagnetic properties of Co-coated carbonyl iron particles/polyimide composite

    Science.gov (United States)

    Zhou, Yingying; Zhou, Wancheng; Li, Rong; Qing, Yuchang; Luo, Fa; Zhu, Dongmei

    2016-03-01

    To solve the serious electromagnetic interference problems at elevated temperature, one thin microwave-absorbing sheet employing Co-coated carbonyl iron particles and polyimide was prepared. The Co-coated carbonyl iron particles were successfully prepared using an electroless plating method. The microstructure, composition, phase and static magnetic properties of Co-coated carbonyl iron particles were characterized by combination of scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The electromagnetic parameters of Co-coated carbonyl iron particles/polyimide composite were measured in the frequency range of 2-18 GHz, and the electromagnetic loss mechanism of the material-obtained was discussed. The microwave absorption properties of composites before and after heat treatment at 300 °C for 100 h were characterized in 2-18 GHz frequency range. It was established that composites based on Co-coated carbonyl iron demonstrate thermomagnetic stability, indicating that Co coating reduces the oxidation of carbonyl iron. Thus, Co-coated carbonyl iron particles/polyimide composites are useful in the design of microwave absorbers operating at temperatures up to 300 °C.

  3. Structural Elucidation of Chalcone Reductase and Implications for Deoxychalcone Biosynthesis

    Science.gov (United States)

    Bomati, Erin K.; Austin, Michael B.; Bowman, Marianne E.; Dixon, Richard A.; Noel, Joseph P.

    2010-01-01

    4,2′,4′,6′-tetrahydroxychalcone (chalcone) and 4,2′,4′-trihydroxychalcone (deoxychalcone) serve as precursors of ecologically important flavonoids and isoflavonoids. Deoxychalcone formation depends on chalcone synthase and chalcone reductase; however, the identity of the chalcone reductase substrate out of the possible substrates formed during the multistep reaction catalyzed by chalcone synthase remains experimentally elusive. We report here the three-dimensional structure of alfalfa chalcone reductase bound to the NADP+ cofactor and propose the identity and binding mode of its substrate, namely the non-aromatized coumaryl-trione intermediate of the chalcone synthase-catalyzed cyclization of the fully extended coumaryl-tetraketide thioester intermediate. In the absence of a ternary complex, the quality of the refined NADP+-bound chalcone reductase structure serves as a template for computer-assisted docking to evaluate the likelihood of possible substrates. Interestingly, chalcone reductase adopts the three-dimensional structure of the aldo/keto reductase superfamily. The aldo/keto reductase fold is structurally distinct from all known ketoreductases of fatty acid biosynthesis, which instead belong to the short-chain dehydrogenase/reductase superfamily. The results presented here provide structural support for convergent functional evolution of these two ketoreductases that share similar roles in the biosynthesis of fatty acids/polyketides. In addition, the chalcone reductase structure represents the first protein structure of a member of the aldo/ketoreductase 4 family. Therefore, the chalcone reductase structure serves as a template for the homology modeling of other aldo/ketoreductase 4 family members, including the reductase involved in morphine biosynthesis, namely codeinone reductase. PMID:15970585

  4. Cloning and nitrate induction of nitrate reductase mRNA

    OpenAIRE

    Cheng, Chi-Lien; Dewdney, Julia; Kleinhofs, Andris; Goodman, Howard M.

    1986-01-01

    Nitrate is the major source of nitrogen taken from the soil by higher plants but requires reduction to ammonia prior to incorporation into amino acids. The first enzyme in the reducing pathway is a nitrate-inducible enzyme, nitrate reductase (EC 1.6.6.1). A specific polyclonal antiserum raised against purified barley nitrate reductase has been used to immunoprecipitate in vivo labeled protein and in vitro translation products, demonstrating that nitrate induction increases nitrate reductase p...

  5. FeCl3 -Catalyzed Ring-Closing Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    Ma, Lina; Li, Wenjuan; Xi, Hui; Bai, Xiaohui; Ma, Enlu; Yan, Xiaoyu; Li, Zhiping

    2016-08-22

    Exploiting catalytic carbonyl-olefin metathesis is an ongoing challenge in organic synthesis. Reported herein is an FeCl3 -catalyzed ring-closing carbonyl-olefin metathesis. The protocol allows access to a range of carbo-/heterocyclic alkenes with good efficiency and excellent trans diastereoselectivity. The methodology presents one of the rare examples of catalytic ring-closing carbonyl-olefin metathesis. This process is proposed to take place by FeCl3 -catalyzed oxetane formation followed by retro-ring-opening to deliver metathesis products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Peroxisomal trans-2-enoyl-CoA reductase is involved in phytol degradation.

    Science.gov (United States)

    Gloerich, J; Ruiter, J P N; van den Brink, D M; Ofman, R; Ferdinandusse, S; Wanders, R J A

    2006-04-03

    Phytol is a naturally occurring precursor of phytanic acid. The last step in the conversion of phytol to phytanoyl-CoA is the reduction of phytenoyl-CoA mediated by an, as yet, unidentified enzyme. A candidate for this reaction is a previously described peroxisomal trans-2-enoyl-CoA reductase (TER). To investigate this, human TER was expressed in E. coli as an MBP-fusion protein. The purified recombinant protein was shown to have high reductase activity towards trans-phytenoyl-CoA, but not towards the peroxisomal beta-oxidation intermediates C24:1-CoA and pristenoyl-CoA. In conclusion, our results show that human TER is responsible for the reduction of phytenoyl-CoA to phytanoyl-CoA in peroxisomes.

  7. Atmospheric Sulfur Cycle Effects of Carbonyl Sulfide (OCS)

    Science.gov (United States)

    McBee, Joshua

    1996-01-01

    Carbonyl Sulfide(OCS) is considered to be one of the major sources of sulfur appearing in the stratosphere due to its relative inertness, about I to 10 yearsl. However, the roles of OCS as well as other reduced sulfur compounds such as carbon disulfide (CS2), hydrogen sulfide (H2S), and dimethyl disulfide(CH3)2S2, are not completely understood in the atmosphenc sulfur cycle. Consequently vely little information is available about the effect of sulfur compounds in the stratosphere. The ability of OCS to penetrate into the stratosphere makes it an excellent tracer for study of the role of the sulfi r cycle in stratospheric chemistry. Previously techniques such as gas chromatography and whole air sampling have been used to measure OCS analytically. Each technique had its drawbacks however, with both being quite slow, and whole air sampling being somewhat unreliable. With molecular spectroscopy, however, it has been found in recent years that the tunable diode laser absorption spectrometer (TDL) provides a very rapid and accurate method of measuring OCS and other trace gases

  8. Tropical sources and sinks of carbonyl sulfide observed from space

    Science.gov (United States)

    Glatthor, Norbert; Höpfner, Michael; Baker, Ian T.; Berry, Joe; Campbell, Elliott; Kawa, Stephan R.; Krysztofiak, Gisele; Sinnhuber, Björn-Martin; Stiller, Gabriele; Stinecipher, Jim; von Clarmann, Thomas

    2016-04-01

    According to current budget estimations the seasonal variation of carbonyl sulfide (COS) is governed by oceanic release and vegetation uptake. Its assimilation by plants is assumed to be similar to the photosynthetic uptake of CO2 but, contrary to the latter process, to be irreversible. Therefore COS has been suggested as co-tracer of the carbon cycle. Observations of COS, however, are sparse, especially in tropical regions. We use the comprehensive data set of spaceborne measurements of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) to analyze its global distribution. Two major features are observed in the tropical upper troposphere around 250 hPa: enhanced amounts over the western Pacific and the Maritime Continent, peaking around 550 pptv in boreal summer, and a seasonally varying depletion of COS extending from tropical South America to Africa. The large-scale COS depletion, which in austral summer amounts up to -40 pptv as compared to the rest of the respective latitude band, has not been observed before and reveals the seasonality of COS uptake through tropical vegetation. The observations can only be reproduced by global models, when a large vegetation uptake and a corresponding increase in oceanic emissions as proposed in several recent publications is assumed.

  9. Photodecomposition of Molybdenum andTungsten Carbonyl Complexes

    Directory of Open Access Journals (Sweden)

    Thamer A. Alwani

    2009-01-01

    Full Text Available The photodecomposition of four different colored organometallic molybdenum and tungsten carbonyl complexes, i.e. [Mo(CO52LA] (complex I, [(Mo(CO3(bipy2LB] (complex II, [(W(CO3(tmen2LB] (complex III and [Mo(CO2LC]2 (complex I V where LA 2-phenyl-1,3-indandionebis(2-methyl anilines, LB 2-phenyl-1,3-indandione bis (4-hydroxy anilines and LCbis (2-hydroxo-benzalydine benzidine ion have been performed at 365 nm in chloroform at 25 °C under oxygen atmosphere. The absorbance spectrum of these complexes has been recorded with the time of irradiation in order to examine the kinetics of photodecomposition. The rate of the photodecomposition process was investigated and the relative values of the rate constants of dissociation (Kd for the first-order reaction are tabulated. The apparent rate constant of photodecomposition was found to be (8.33-11.50 × 10-5 s-1.

  10. Carbonyl Sulfide for Tracing Carbon Fluxes Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J. Elliott [Univ. of California, Merced, CA (United States); Berry, Joseph A. [Carnegie Inst. of Science, Stanford, CA (United States); Billesbach, Dave [Univ. of Nebraska, Lincoln, NE (United States); Torn, Margaret S [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zahniser, Mark [Aerodyne Research, Inc., Billerica, MA (United States); Seibt, Ulrike [Univ. of California, Los Angeles, CA (United States); Maseyk, Kadmiel [Pierre and Marie Curie Univ., Paris (France)

    2016-04-01

    The April-June 2012 campaign was located at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) site Central Facility and had three purposes. One goal was to demonstrate the ability of current instrumentation to correctly measure fluxes of atmospheric carbonyl sulfide (COS). The approach has been describe previously as a critical approach to advancing carbon cycle science1,2, but requires further investigation at the canopy scale to resolve ecosystem processes. Previous canopy-scale efforts were limited to data rates of 1Hz. While 1 Hz measurements may work in a few ecosystems, it is widely accepted that data rates of 10 to 20 Hz are needed to fully capture the exchange of traces gases between the atmosphere and vegetative canopy. A second goal of this campaign was to determine if canopy observations could provide information to help interpret the seasonal double peak in airborne observations at SGP of CO2 and COS mixing ratios. A third goal was to detect potential sources and sinks of COS that must be resolved before using COS as a tracer of gross primary productivity (GPP).

  11. Thermal characterization of magnetically aligned carbonyl iron/agar composites.

    Science.gov (United States)

    Diaz-Bleis, D; Vales-Pinzón, C; Freile-Pelegrín, Y; Alvarado-Gil, J J

    2014-01-01

    Composites of magnetic particles into polymeric matrices have received increasing research interest due to their capacity to respond to external magnetic or electromagnetic fields. In this study, agar from Gelidium robustum has been chosen as natural biocompatible polymer to build the matrix of the magnetic carbonyl iron particles (CIP) for their uses in biomedical fields. Heat transfer behavior of the CIP-agar composites containing different concentrations (5, 10, 15, 20, 25 and 30% w/w) of magnetically aligned and non-aligned CIP in the agar matrix was studied using photothermal radiometry (PTR) in the back-propagation emission configuration. The morphology of the CIP-agar composites with aligned and non-aligned CIP under magnetic field was also evaluated by scanning electron microscopy (SEM). The results revealed a dominant effect of CIP concentration over the alignment patterns induced by the magnetic field, which agrees with the behavior of the thermal diffusivity and thermal conductivity. Agar served as a perfect matrix to be used with CIP, and CIP-agar composites magnetically aligned at 20% CIP concentration can be considered as promising 'smart' material for hyperthermia treatments in the biomedical field. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. New 5alpha-reductase inhibitors: in vitro and in vivo effects.

    Science.gov (United States)

    Pérez-Ornelas, Víctor; Cabeza, Marisa; Bratoeff, Eugene; Heuze, Ivonne; Sánchez, Mauricio; Ramírez, Elena; Naranjo-Rodríguez, Elia

    2005-03-01

    The enzyme 5alpha-reductase is responsible for the conversion of testosterone (T) to its more potent androgen dihydrotestosterone (DHT). This steroid had been implicated in androgen-dependent diseases such as: benign prostatic hyperplasia, prostate cancer, acne and androgenic alopecia. The inhibition of 5alpha-reductase enzyme offers a potentially useful treatment for these diseases. In this study, we report the synthesis and pharmacological evaluation of several new 3-substituted pregna-4, 16-diene-6, 20-dione derivatives. These compounds were prepared from the commercially available 16-dehydropregnenolone acetate. The biological activity of the new steroidal derivatives was determined in vivo as well as in vitro experiments. In vivo experiments, the anti-androgenic effect of the steroids was demonstrated by the decrease of the weight of the prostate gland of gonadectomized hamster treated with T plus finasteride or the new steroids. The IC50 value of these steroids was determined by measuring the conversion of radio labeled T to DHT. The results of this study carried out with 5alpha-reductase enzyme from hamster and human prostate showed that four of the six steroidal derivatives (5, 7, 9, 10) exhibited much higher 5alpha-reductase inhibitory activity, as indicated by the IC50 values than the presently used Proscar 3 (finasteride). The comparison of the weight of the hamster's prostate gland indicated that compound 5 had a comparable weight decrease as finasteride. The overall data of this study showed very clearly those compounds 5, 7, 9, 10 are good inhibitors for the 5alpha-reductase enzyme.

  13. The Fungal Pathogen Candida glabrata Does Not Depend on Surface Ferric Reductases for Iron Acquisition

    Directory of Open Access Journals (Sweden)

    Franziska Gerwien

    2017-06-01

    Full Text Available Iron acquisition is a crucial virulence determinant for many bacteria and fungi, including the opportunistic fungal pathogens Candida albicans and C. glabrata. While the diverse strategies used by C. albicans for obtaining iron from the host are well-described, much less is known about the acquisition of this micronutrient from host sources by C. glabrata – a distant relative of C. albicans with closer evolutionary ties to Saccharomyces cerevisiae, which nonetheless causes severe clinical symptoms in humans. Here we show that C. glabrata is much more restricted than C. albicans in using host iron sources, lacking, for example, the ability to grow on transferrin and hemin/hemoglobin. Instead, C. glabrata is able to use ferritin and non-protein-bound iron (FeCl3 as iron sources in a pH-dependent manner. As in other fungal pathogens, iron-dependent growth requires the reductive high affinity (HA iron uptake system. Typically highly conserved, this uptake mechanism normally relies on initial ferric reduction by cell-surface ferric reductases. The C. glabrata genome contains only three such putative ferric reductases, which were found to be dispensable for iron-dependent growth. In addition and in contrast to C. albicans and S. cerevisiae, we also detected no surface ferric reductase activity in C. glabrata. Instead, extracellular ferric reduction was found in this and the two other fungal species, which was largely dependent on an excreted low-molecular weight, non-protein ferric reductant. We therefore propose an iron acquisition strategy of C. glabrata which differs from other pathogenic fungi, such as C. albicans, in that it depends on a limited set of host iron sources and that it lacks the need for surface ferric reductases. Extracellular ferric reduction by a secreted molecule possibly compensates for the loss of surface ferric reductase activity in the HA iron uptake system.

  14. The Development and Application of Two-Chamber Reactors and Carbon Monoxide Precursors for Safe Carbonylation Reactions.

    Science.gov (United States)

    Friis, Stig D; Lindhardt, Anders T; Skrydstrup, Troels

    2016-04-19

    Low molecular weight gases (e.g., carbon monoxide, hydrogen, and ethylene) represent vital building blocks for the construction of a wide array of organic molecules. Whereas experimental organic chemists routinely handle solid and liquid reagents, the same is not the case for gaseous reagents. Synthetic transformations employing such reagents are commonly conducted under pressure in autoclaves or under atmospheric pressure with a balloon setup, which necessitates either specialized equipment or potentially hazardous and nonrecommended installations. Other safety concerns associated with gaseous reagents may include their toxicity and flammability and, with certain gases, their inability to be detected by human senses. Despite these significant drawbacks, industrial processes apply gaseous building blocks regularly due to their low cost and ready availability but nevertheless under a strictly controlled manner. Carbon monoxide (CO) fits with all the parameters for being a gas of immense industrial importance but with severe handling restrictions due to its inherent toxicity and flammability. In academia, as well as research and development laboratories, CO is often avoided because of these safety issues, which is a limitation for the development of new carbonylation reactions. With our desire to address the handling of CO in a laboratory setting, we designed and developed a two-chamber reactor (COware) for the controlled delivery and utilization of stoichiometric amounts of CO for Pd-catalyzed carbonylation reactions. In addition to COware, two stable and solid CO-releasing molecules (COgen and SilaCOgen) were developed, both of which release CO upon activation by either Pd catalysis or fluoride addition, respectively. The unique combination of COware with either COgen or SilaCOgen provides a simple reactor setup enabling synthetic chemists to easily perform safe carbonylation chemistry without the need for directly handling the gaseous reagent. With this technology

  15. Hypothesis on Serenoa repens (Bartram) small extract inhibition of prostatic 5α-reductase through an in silico approach on 5β-reductase x-ray structure.

    Science.gov (United States)

    Governa, Paolo; Giachetti, Daniela; Biagi, Marco; Manetti, Fabrizio; De Vico, Luca

    2016-01-01

    Benign prostatic hyperplasia is a common disease in men aged over 50 years old, with an incidence increasing to more than 80% over the age of 70, that is increasingly going to attract pharmaceutical interest. Within conventional therapies, such as α-adrenoreceptor antagonists and 5α-reductase inhibitor, there is a large requirement for treatments with less adverse events on, e.g., blood pressure and sexual function: phytotherapy may be the right way to fill this need. Serenoa repens standardized extract has been widely studied and its ability to reduce lower urinary tract symptoms related to benign prostatic hyperplasia is comprehensively described in literature. An innovative investigation on the mechanism of inhibition of 5α-reductase by Serenoa repens extract active principles is proposed in this work through computational methods, performing molecular docking simulations on the crystal structure of human liver 5β-reductase. The results confirm that both sterols and fatty acids can play a role in the inhibition of the enzyme, thus, suggesting a competitive mechanism of inhibition. This work proposes a further confirmation for the rational use of herbal products in the management of benign prostatic hyperplasia, and suggests computational methods as an innovative, low cost, and non-invasive process for the study of phytocomplex activity toward proteic targets.

  16. Hypothesis on Serenoa repens (Bartram small extract inhibition of prostatic 5α-reductase through an in silico approach on 5β-reductase x-ray structure

    Directory of Open Access Journals (Sweden)

    Paolo Governa

    2016-11-01

    Full Text Available Benign prostatic hyperplasia is a common disease in men aged over 50 years old, with an incidence increasing to more than 80% over the age of 70, that is increasingly going to attract pharmaceutical interest. Within conventional therapies, such as α-adrenoreceptor antagonists and 5α-reductase inhibitor, there is a large requirement for treatments with less adverse events on, e.g., blood pressure and sexual function: phytotherapy may be the right way to fill this need. Serenoa repens standardized extract has been widely studied and its ability to reduce lower urinary tract symptoms related to benign prostatic hyperplasia is comprehensively described in literature. An innovative investigation on the mechanism of inhibition of 5α-reductase by Serenoa repens extract active principles is proposed in this work through computational methods, performing molecular docking simulations on the crystal structure of human liver 5β-reductase. The results confirm that both sterols and fatty acids can play a role in the inhibition of the enzyme, thus, suggesting a competitive mechanism of inhibition. This work proposes a further confirmation for the rational use of herbal products in the management of benign prostatic hyperplasia, and suggests computational methods as an innovative, low cost, and non-invasive process for the study of phytocomplex activity toward proteic targets.

  17. Efficient and selective α-bromination of carbonyl compounds with N-bromosuccinimide under microwave

    KAUST Repository

    Guan, Xiao-Yu

    2014-02-07

    A highly efficient method for the synthesis of α-halocarbonyl compounds has been achieved via selective monobromination of aromatic and aliphatic carbonyl compounds with N-bromosuccinimide catalyzed by p-toluenesulfonic acid under microwave irradiation within 30 min.

  18. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Matthias, E-mail: matthias.schindler@physik.uni-erlangen.de; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-15

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO{sub 2} and reduced to graphite to determine {sup 14}C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  19. Two-dimensional gel electrophoretic detection of protein carbonyls derivatized with biotin-hydrazide.

    Science.gov (United States)

    Wu, Jinzi; Luo, Xiaoting; Jing, Siqun; Yan, Liang-Jun

    2016-04-15

    Protein carbonyls are protein oxidation products that are often used to measure the magnitude of protein oxidative damage induced by reactive oxygen or reactive nitrogen species. Protein carbonyls have been found to be elevated during aging and in age-related diseases such as stroke, diabetes, and neurodegenerative diseases. In the present article, we provide detailed protocols for detection of mitochondrial protein carbonyls labeled with biotin-hydrazide followed by 2-dimensional isoelectric focusing (IEF)/SDS-PAGE and Western blotting probed with horse-radish peroxidase-conjugated streptavidin. The presented procedures can also be modified for detection of carbonylation of non-mitochondrial proteins. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Sulfenamide catalyzed oxidation of alcohols to the corresponding carbonyl compounds with anhydrous chloramine-T.

    Science.gov (United States)

    Kitagawa, Hideo; Mukaiyama, Teruaki

    2002-09-01

    N-tert-Butylbenzenesulfenamide (1) catalyzed oxidation of various alcohols with stoichiometric amount of anhydrous chloramines-T (2) proceeded smoothly at room temperature to afford the corresponding carbonyl compounds in good yields.

  1. Enoate reductases from non conventional yeasts: bioconversion, cloning, and functional expression in Saccharomyces cerevisiae.

    Science.gov (United States)

    Raimondi, Stefano; Romano, Diego; Amaretti, Alberto; Molinari, Francesco; Rossi, Maddalena

    2011-12-20

    Old yellow enzymes (OYEs, EC 1.6.99.1) are flavin-dependent oxidoreductases that catalyze the stereoselective trans-hydrogenation of the double bond, representing a promising alternative to metal-based catalysis. Bioconversion of ketoisophorone (KIP) by 28 non-conventional yeasts belonging to 16 different species was investigated. Growing cells of most of the strains reduced KIP via OYE and showed high stereoselectivity, producing R-levodione as major product. Competition by carbonyl reductase (CR) activity was observed in several strains. The best performing yeasts belong to Candida castellii, Kazachstania spencerorum and Kluyveromyces marxianus exhibited yields of levodione ≥77% up to 95% e.e., and. Candida freyschussii, the sole strain lacking the OYE gene, reduced KIP only to unsaturated alcohols via CR. Nine unedited OYE genes were cloned, sequenced, and heterologously expressed in Saccharomyces cerevisiae BY4741ΔOye2, a mutant that showed negligible OYE and CR activities. Compared with the corresponding wild-type yeasts, growing cells of the recombinant strains bioconverted KIP with improved yields of OYE products, minor competition by CR activity, and lower enantioselectivity. In particular, resting cells of recombinant S. cerevisae presented the best performance in KIP bioconversion. Based on the results herein reported, selected strains of non-conventional yeasts and novel OYE genes can be profitably used as innovative biocatalysts in asymmetric reductions. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Trypanocidal Activity of Quinoxaline 1,4 Di-N-oxide Derivatives as Trypanothione Reductase Inhibitors

    Directory of Open Access Journals (Sweden)

    Karla Fabiola Chacón-Vargas

    2017-02-01

    Full Text Available Chagas disease or American trypanosomiasis is a worldwide public health problem. In this work, we evaluated 26 new propyl and isopropyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives as potential trypanocidal agents. Additionally, molecular docking and enzymatic assays on trypanothione reductase (TR were performed to provide a basis for their potential mechanism of action. Seven compounds showed better trypanocidal activity on epimastigotes than the reference drugs, and only four displayed activity on trypomastigotes; T-085 was the lead compound with an IC50 = 59.9 and 73.02 µM on NINOA and INC-5 strain, respectively. An in silico analysis proposed compound T-085 as a potential TR inhibitor with better affinity than the natural substrate. Enzymatic analysis revealed that T-085 inhibits parasite TR non-competitively. Compound T-085 carries a carbonyl, a CF3, and an isopropyl carboxylate group at 2-, 3- and 7-position, respectively. These results suggest the chemical structure of this compound as a good starting point for the design and synthesis of novel trypanocidal derivatives with higher TR inhibitory potency and lower toxicity.

  3. Targeting aldose reductase for the treatment of diabetes complications and inflammatory diseases: new insights and future directions.

    Science.gov (United States)

    Maccari, Rosanna; Ottanà, Rosaria

    2015-03-12

    Aldose reductase (AR) is an aldo-keto reductase that has been widely investigated as an enzyme crucially involved in the pathogenesis of chronic complications associated with diabetes mellitus. Recently it was established that AR also acts as a key mediator of certain oxidative and inflammatory signaling pathways that are involved in the development of different human pathologies, such as cardiovascular disorders, sepsis, and cancer. These findings have renewed interest in the search for new AR inhibitors (ARIs) with improved profiles as potential therapeutic agents. In this review, recent advances in the field and promising future directions for developing ARIs are discussed.

  4. Prognostic significance of numeric aberrations of genes for thymidylate synthase, thymidine phosphorylase and dihydrofolate reductase in colorectal cancer

    DEFF Research Database (Denmark)

    Jensen, Søren Astrup; Vainer, B.; Witton, C.J.

    2008-01-01

    BACKGROUND: Most human cancer cells have structural aberrations of chromosomal regions leading to loss or gain of gene specific alleles. This study aimed to assess the range of gene copies per nucleus of thymidylate synthase (TYMS), thymidine phosphorylase (TP) and dihydrofolate reductase (DHFR...

  5. Dipolar cycloaddition of rhodium-generated carbonyl ylides with p-quinones.

    Science.gov (United States)

    Pirrung, M C; Kaliappan, K P

    2000-02-10

    [reaction: see text] The dipolar cycloaddition of carbonyl ylides generated by the rhodium-catalyzed decomposition of delta- and epsilon-carbonyl-alpha-diazoketones with p-quinones leads to both C=O and C=C addition products. The product ratio is solvent- and catalyst-dependent and has been optimized to favor formation of either product. The C=C addition products of naphthoquinones are used in the assembly of structures hybridizing the illudin and anthraquinone anticancer agents.

  6. Protein Carbonylation and Aggregation Precede Neuronal Apoptosis Induced by Partial Glutathione Depletion

    Directory of Open Access Journals (Sweden)

    Anushka Dasgupta

    2012-02-01

    Full Text Available While the build-up of oxidized proteins within cells is believed to be toxic, there is currently no evidence linking protein carbonylation and cell death. In the present study, we show that incubation of nPC12 (neuron-like PC12 cells with 50 μM DEM (diethyl maleate leads to a partial and transient depletion of glutathione (GSH. Concomitant with GSH disappearance there is increased accumulation of PCOs (protein carbonyls and cell death (both by necrosis and apoptosis. Immunocytochemical studies also revealed a temporal/spatial relationship between carbonylation and cellular apoptosis. In addition, the extent of all three, PCO accumulation, protein aggregation and cell death, augments if oxidized proteins are not removed by proteasomal degradation. Furthermore, the effectiveness of the carbonyl scavengers hydralazine, histidine hydrazide and methoxylamine at preventing cell death identifies PCOs as the toxic species. Experiments using well-characterized apoptosis inhibitors place protein carbonylation downstream of the mitochondrial transition pore opening and upstream of caspase activation. While the study focused mostly on nPC12 cells, experiments in primary neuronal cultures yielded the same results. The findings are also not restricted to DEM-induced cell death, since a similar relationship between carbonylation and apoptosis was found in staurosporine- and buthionine sulfoximine-treated nPC12 cells. In sum, the above results show for the first time a causal relationship between carbonylation, protein aggregation and apoptosis of neurons undergoing oxidative damage. To the best of our knowledge, this is the first study to place direct (oxidative protein carbonylation within the apoptotic pathway.

  7. Chemoselective Reduction and Alkylation of Carbonyl Functions Using Phosphonium Salts as an in Situ Protecting Groups.

    Science.gov (United States)

    Ohta, Reiya; Fujioka, Hiromichi

    2017-01-01

    Recent progress in the chemoselective reduction and alkylation of carbonyl functions using our in situ protection method is described. Methods that enable reversal or control of the reactivity of a carbonyl functional group are potentially useful. They open up new areas of synthetic organic chemistry and change the concept of retrosynthesis because they remove the need for complicated protection/deprotection sequences. In this account, we discuss the strategy and applications of our in situ protection method using phosphonium salts.

  8. Functionalization of 6-Nitrobenzo[1,3]dioxole with Carbonyl Compounds via TDAE methodology

    Directory of Open Access Journals (Sweden)

    Patrice Vanelle

    2005-05-01

    Full Text Available We report herein the synthesis of substituted 2-(6-nitrobenzo[1,3]dioxol-5-yl-1- aryl ethanols and 2-(6-nitrobenzo[1,3]dioxol-5-yl-propionic acid ethyl esters from the reaction of 5-chloromethyl-6-nitrobenzo[1,3]dioxole with various aromatic carbonyl and α- carbonyl ester derivatives using the tetrakis(dimethylaminoethylene (TDAE methodology.

  9. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite.

    Science.gov (United States)

    Rasmussen, Dominik B; Christensen, Jakob M; Temel, Burcin; Studt, Felix; Moses, Poul Georg; Rossmeisl, Jan; Riisager, Anders; Jensen, Anker D

    2015-06-15

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated acetic acid (CH2DCOOD), when D2O is introduced in the feed during the carbonylation reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C-H Bonds in Aliphatic Amines.

    Science.gov (United States)

    Cabrera-Pardo, Jaime R; Trowbridge, Aaron; Nappi, Manuel; Ozaki, Kyohei; Gaunt, Matthew J

    2017-09-18

    Palladium(II)-catalyzed C-H carbonylation reactions of methylene C-H bonds in secondary aliphatic amines lead to the formation of trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C-H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields for the β-lactam products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effect of a novel steroid (PM-9) on the inhibition of 5alpha-reductase present in Penicillium crustosum broths.

    Science.gov (United States)

    Flores, Eugenio; Cabeza, Marisa; Quiroz, Alexandra; Bratoeff, Eugene; García, Genoveva; Ramírez, Elena

    2003-03-01

    The conversion of testosterone (T) to 5alpha-dihydrotestosterone (DHT) has been demonstrated in Penicillium crustosum broth obtained from fermented pistachios, lemons and corn tortillas. Furthermore, the presence of 5alpha-reductase enzyme, which is responsible for this conversion, has been established by electrophoretical techniques in these cultures.5alpha-Reductase enzyme is also present in animal and human androgen-dependent tissues as well as in prostate and seminal vesicles. The increase of the conversion of T to DHT in prostate gland, has been related to some illnesses such as benign prostate hyperplasia and prostate cancer. Furthermore, treatment with 5alpha-reductase inhibitors such as finasteride reduces the prostate growth. These data have stimulated research for the synthesis of new molecules with antiandrogenic activity, whose biological effect needs to be demonstrated. The purpose of this study is to determine the inhibition pattern of 5alpha-reductase in P. crustosum by finasteride and the new steroidal compound PM-9. K(m) and V(max) values for T, were determined in the broths by Lineweaver-Burk plots using different testosterone concentrations. The inhibition pattern of finasteride and PM-9 was also determined by Lineweaver-Burk using different concentrations of T and inhibitors. Results show that finasteride and PM-9 inhibit 5alpha-reductase present in the broth in a competitive manner.

  12. Differential expression of 5-alpha reductase isozymes in the prostate and its clinical implications

    Directory of Open Access Journals (Sweden)

    Kai Wang

    2014-04-01

    Full Text Available The development of human benign or malignant prostatic diseases is closely associated with androgens, primarily testosterone (T and dihydrotestosterone (DHT. T is converted to DHT by 5-alpha reductase (5-AR isozymes. Differential expression of 5-AR isozymes is observed in both human benign and malignant prostatic tissues. 5-AR inhibitors (5-ARI are commonly used for the treatment of benign prostatic hyperplasia (BPH and were once promoted as chemopreventive agents for prostate cancer (PCa. This review discusses the role of the differential expression of 5-AR in the normal development of the human prostate and in the pathogenesis and progression of BPH and PCa.

  13. Structural and biochemical characterization of cinnamoyl-coa reductases

    Science.gov (United States)

    Cinnamoyl-coenzyme A reductase (CCR) catalyzes the reduction of hydroxycinnamoyl-coenzyme A (CoA) esters using NADPH to produce hydroxycinnamyl aldehyde precursors in lignin synthesis. The catalytic mechanism and substrate specificity of cinnamoyl-CoA reductases from sorghum (Sorghum bicolor), a str...

  14. Optimum conditions for cotton nitrate reductase extraction and ...

    African Journals Online (AJOL)

    GREGO

    nitrate transformation into nitrite (µg of NO2. -/min/g F.W) is observed when incubation period of enzyme is short (1 to 5 min). Key words: Extraction, dosage, nitrate reductase activity, callus, cotton. INTRODUCTION. Nitrate reductase (EC. 1.7.99.4) is an oxidoreductase enzyme involved in nitrogen assimilation in plant. It.

  15. COMPARATIVE STUDY OF EFFICACY OF FERROUS SULPHATE AND CARBONYL IRON IN ANEMIA OF ANTENATAL WOMEN

    Directory of Open Access Journals (Sweden)

    Radhika

    2015-03-01

    Full Text Available Iron deficiency anemia is the most common and important public health problem all over the world in the risk group of antenatal women. Research is going on to improve the iron status of the pregnant women with different forms of iron available. In this regard, Carbonyl Iron is showing promising results in improving the red cell mass with better compliance. 120 antenatal women were recruited in this study. The study comprised of 6weeks for each patient. They were given Carbonyl Iron 100 mg/day and FeS04 100gm/day . Before and after treatment all the baseline and specific investigations were one. Results were tabulated, comparison and significance were tested by unpaired student ’s’ test and their 'p' value was calculated. Results were shown graphically also. Carbonyl Iron showed improvement in hemoglobin, PCV and better than ferrous Sulphate (P <0.001. Incidence of side effects were less with Carbonyl Iron than Ferrous Sulphate, better compliance was seen with Carbonyl Iron. In conclusion, the present study s howed that Carbonyl Iron had better efficacy and safety in the management of Iron deficiency anemia in antenatal women than ferrous Sulphate

  16. Characteristics of carbonyl compounds in public vehicles of Beijing city: Concentrations, sources, and personal exposures

    Science.gov (United States)

    Pang, Xiaobing; Mu, Yujing

    The characteristics of carbonyl compounds (carbonyls) including concentrations, major sources, and personal exposure were investigated for 29 vehicles including taxi, bus and subway in Beijing. It was found that the taxis (Xiali, TA) and buses (Huanghe, BA) fueled by gasoline with longer service years had the higher indoor carbonyl levels (178±42.7 and 188±31.6 μg m -3) while subways energized by electricity without exhaust and the jingwa buses (BB) driven in the suburb had the lower levels with total concentrations of 98.5±26.3 and 92.1±20.3 μg m -3, respectively. Outdoor carbonyls of taxi cars and buses were nearly at the same level with their total concentrations varying from 80 to 110 μg m -3. The level of outdoor subways carbonyls was equal with the ambient air levels. Exhaust leakage, indoor material emissions, photochemical formation, and infiltration of outdoor air were considered to be the major sources to in-vehicle carbonyls. Personal exposures and cancer risk to formaldehyde and acetaldehyde were calculated for professional bus and taxi drivers, respectively. Taxi drivers had the highest cancer risk with personal exposure to formaldehyde and acetaldehyde of 212 and 243 μg day -1, respectively. The public concern should pay considerable attention to professional drivers' health.

  17. Brand variation in oxidant production in mainstream cigarette smoke: Carbonyls and free radicals.

    Science.gov (United States)

    Reilly, Samantha M; Goel, Reema; Trushin, Neil; Elias, Ryan J; Foulds, Jonathan; Muscat, Joshua; Liao, Jason; Richie, John P

    2017-08-01

    Oxidative stress/damage resulting from exposure to cigarette smoke plays a critical role in the development of tobacco-caused diseases. Carbonyls and free radicals are two major classes of oxidants in tobacco smoke. There is little information on the combined delivery of these oxidants across different cigarette brands; thus, we set out to measure and compare their levels in mainstream smoke from popular US cigarettes. Mainstream smoke from 28 different cigarette brands produced by smoking (FTC protocol) was analyzed for five important, abundant carbonyls, and levels were compared to previously determined free radical for the same brands. Overall, there were large variations (3- to 6-fold) in carbonyl levels across brands with total carbonyl levels ranging from 275 to 804 μg/cigarette, which persisted even after adjusting for ventilation. Individual carbonyl levels were highly correlated with each other (r2: 0.40-0.95, P < 0.003) except for formaldehyde. Both gas-phase (r2: 0.37, P = 0.006) and particulate-phase (r2: 0.27, P = 0.005) free radicals were correlated to total carbonyl content; however, this correlation disappeared after adjusting for ventilation. These data show that overall oxidant production varies widely by cigarette brand and the resulting difference in oxidant burden could potentially lead to differences in disease risk. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Characterization of human liver enzymes involved in the biotransformation of boceprevir, a hepatitis C virus protease inhibitor.

    Science.gov (United States)

    Ghosal, Anima; Yuan, Yuan; Tong, Wei; Su, Ai-Duen; Gu, Chunyan; Chowdhury, Swapan K; Kishnani, Narendra S; Alton, Kevin B

    2011-03-01

    Boceprevir (SCH 503034), a protease inhibitor, is under clinical development for the treatment of human hepatitis C virus infections. In human liver microsomes, formation of oxidative metabolites after incubations with [(14)C]boceprevir was catalyzed by CYP3A4 and CYP3A5. In addition, the highest turnover was observed in recombinant CYP3A4 and CYP3A5. After a single radiolabeled dose to human, boceprevir was subjected to two distinct pathways, namely cytochrome P450-mediated oxidation and ketone reduction. Therefore, attempts were made to identify the enzymes responsible for the formation of carbonyl-reduced metabolites. Human liver S9 and cytosol converted ∼ 28 and ∼ 68% of boceprevir to M28, respectively, in the presence of an NADPH-generating system. Screening of boceprevir with recombinant human aldo-keto reductases (AKRs) revealed that AKR1C2 and AKR1C3 exhibited catalytic activity with respect to the formation of M+2 metabolites (M28 and M31). The formation of M28 was inhibited by 100 μM flufenamic acid (80.3%), 200 μM mefenamic acid (83.7%), and 100 μM phenolphthalein (86.1%), known inhibitors of AKRs, suggesting its formation through carbonyl reduction pathway. Formation of M28 was also inhibited by 100 μM diazepam (75.1%), 1 mM ibuprofen (70%), and 200 μM diflunisal (89.4%). These data demonstrated that CYP3A4 and CYP3A5 are primarily responsible for the formation of oxidative metabolites and the formation of M28 and M31, the keto-reduced metabolites, are most likely mediated by AKR1C2 and AKR1C3. Because the biotransformation and clearance of boceprevir involves two different enzymatic pathways, boceprevir is less likely to be a victim of significant drug-drug interaction with concomitant medication affecting either of these pathways.

  19. New Ir Bis-Carbonyl Precursor for Water Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Daria L. [Department of Chemistry, Yale University, 225; Beltrán-Suito, Rodrigo [Department of Chemistry, Yale University, 225; Thomsen, Julianne M. [Department of Chemistry, Yale University, 225; Hashmi, Sara M. [Department of Chemical and Environmental; Materna, Kelly L. [Department of Chemistry, Yale University, 225; Sheehan, Stafford W. [Catalytic Innovations LLC, 70 Crandall; Mercado, Brandon Q. [Department of Chemistry, Yale University, 225; Brudvig, Gary W. [Department of Chemistry, Yale University, 225; Crabtree, Robert H. [Department of Chemistry, Yale University, 225

    2016-02-05

    This paper introduces IrI(CO)2(pyalc) (pyalc = (2-pyridyl)-2-propanoate) as an atom-efficient precursor for Ir-based homogeneous oxidation catalysis. This compound was chosen to simplify analysis of the water oxidation catalyst species formed by the previously reported Cp*IrIII(pyalc)OH water oxidation precatalyst. Here, we present a comparative study on the chemical and catalytic properties of these two precursors. Previous studies show that oxidative activation of Cp*Ir-based precursors with NaIO4 results in formation of a blue IrIV species. This activation is concomitant with the loss of the placeholder Cp* ligand which oxidatively degrades to form acetic acid, iodate, and other obligatory byproducts. The activation process requires substantial amounts of primary oxidant, and the degradation products complicate analysis of the resulting IrIV species. The species formed from oxidation of the Ir(CO)2(pyalc) precursor, on the other hand, lacks these degradation products (the CO ligands are easily lost upon oxidation) which allows for more detailed examination of the resulting Ir(pyalc) active species both catalytically and spectroscopically, although complete structural analysis is still elusive. Once Ir(CO)2(pyalc) is activated, the system requires acetic acid or acetate to prevent the formation of nanoparticles. Investigation of the activated bis-carbonyl complex also suggests several Ir(pyalc) isomers may exist in solution. By 1H NMR, activated Ir(CO)2(pyalc) has fewer isomers than activated Cp*Ir complexes, allowing for advanced characterization. Future research in this direction is expected to contribute to a better structural understanding of the active species. A diol crystallization agent was needed for the structure determination of 3.

  20. Binding of ether and carbonyl oxygens to lithium ion

    Energy Technology Data Exchange (ETDEWEB)

    Blint, R.J. [Physical Chemistry Dept., Warren, MI (United States)

    1994-12-31

    The electrolyte for a lithium battery is a lithium salt (e.g. lithium Perchlorate) dissolved in an organic solvent or a mixture of organic solvents. The conductivity in these electrolytes is ionic and needs to be as high as possible to efficiently remove energy from the battery. The diffusion coefficient of the solvated ion in liquid electrolytes is inversely dependent on the radius of the salvation sphere. Consequently conductivity will increase with a decrease in the size of the salvation shell. The size of the salvation shell is determined by the size and coordination number of the solvent molecules. The types of organic solvents in electrolytes used in lithium battery applications are usually differentiated based on their perceived solvation properties. These solvents are often small, oxygen containing organic molecules which move with the Li{sup +} ions. This paper calculates the binding energies of some of these solvents to Li{sup +} using molecular quantum mechanics (MQM) techniques. The binding energies of the various solvents to Li{sup +} may determine which solvents will be preferentially bound to the ion. In liquid organic electrolytes, then, it will be the identity of the solvent and the coordination number which most affect the conductivity; the binding energies determine both of these properties. Carbonyl oxygens which occur in formaldehyde, acetaldehyde, acetone, ethylene carbonate and propylene carbonate have different Li{sup +} bonding properties than do the ether oxygens which occur in water, dimethyl ether and diethyl ether. Polymer solvents for the lithium salts such as the polyethers have chains which are too long to move with the binding energies then serve as the basis for a different Li{sup +} transport. Dimethyl ether and diethyl ether serve both as solvents and models for the polyethers.

  1. Plasma protein carbonyl responses to anaerobic exercise in female cyclists

    Directory of Open Access Journals (Sweden)

    M.E Afzalpour

    2016-03-01

    Full Text Available Single bouts of aerobic exercise may leads to oxidative stress due to the use of oxygen for metabolism and the generation of reactive oxygen. In athletes, oxidative stress can lead to several deleterious performance effects, such as muscular oxidative damage, muscle soreness, loss of skeletal muscle force production and/or inflammation. However, little is known regarding the severity and duration of oxidative stress arising from intensive anaerobic modes of exercise in aerobically-trained athletes. The purpose of this study was to investigate the effect of a single bout of intensive anaerobic exercise on plasma protein carbonyl (PC in aerobically-trained women. Aerobically-trained, provincial female cyclists [n = 18, age: 24.2±2.7 years; stature: 163.6±4.6 cm; body mass: 53.4±4.2 kg] were randomly assigned into either a non-exercising control (CON; n = 9 or experimental (EXP; n = 9 group that underwent a 30-second anaerobic (Wingate cycle ergometer exercise session. Blood sampling took place before exercise, immediately after the exercise (IE, and 24 hours following the exercise (24HR bout. In the EXP, results indicated significant (P ≤ 0.05 differences in PC levels between the pre-test and IE (0.010±0.0124 to 0.0149±0.0420 mmol/milt; P = 0.010, and IE and 24HR (0.0149±0.0420 to 0.0111±0.0183 mmol/milt; P = 0.013. No significant differences were observed between pre-test and 24HR (0.010±0.0124 to 0.0111±0.0183 mmol/milt; P = 0.371. These results indicate that oxidative protein damage, as indicated by PC levels, rises immediately with the onset of anaerobic exercise, but returns to resting levels within 24 hours following exercise in aerobically-trained women.

  2. Intramolecular Hydrogen Bond in Biologically Active o-Carbonyl Hydroquinones

    Directory of Open Access Journals (Sweden)

    Maximiliano Martínez-Cifuentes

    2014-07-01

    Full Text Available Intramolecular hydrogen bonds (IHBs play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculations at the DFT and ab initio levels. Natural bond orbital (NBO and molecular electrostatic potential (MEP calculations were used to study the electronic characteristics of these IHB. As expected, our results show that NBO calculations are better than MEP to describe the strength of the IHBs. NBO energies (∆Eij(2 show that the main contributions to energy stabilization correspond to LPàσ* interactions for IHBs, O1…O2-H2 and the delocalization LPàπ* for O2-C2 = Cα(β. For the O1…O2-H2 interaction, the values of ∆Eij(2 can be attributed to the difference in the overlap ability between orbitals i and j (Fij, instead of the energy difference between them. The large energy for the LP O2àπ* C2 = Cα(β interaction in the compounds 9-Hydroxy-5-oxo-4,8, 8-trimethyl-l,9(8H-anthracenecarbolactone (VIII and 9,10-dihydroxy-4,4-dimethylanthracen-1(4H-one (VII (55.49 and 60.70 kcal/mol, respectively when compared with the remaining molecules (all less than 50 kcal/mol, suggests that the IHBs in VIII and VII are strongly resonance assisted.

  3. Organometallic and Bioorganometallic Chemistry - Ferrocene and Metal Carbonyls

    Directory of Open Access Journals (Sweden)

    Čakić Semenčić, M.

    2011-02-01

    Full Text Available Organometallic chemistry deals with compounds containing metal-carbon bonds. Basic organometallics derived from the s- and p-block metals (containing solely σ-bonds were understood earlier, while organometallic chemistry of the d- and f-block has developed much more recently. These compounds are characterized by three types of M-C bonds (σ, π and δand their structures are impossible to deduce by chemical means alone; fundamental advances had to await the development of X-ray diffraction, as well as IR- and NMR-spectroscopy. On the other hand, elucidation of the structure of e. g. vitamin B12 and ferrocene (discovered in 1951 contributed to progress in these instrumental analytical methods, influencing further phenomenal success of transition-metal organometallic chemistry in the second half of the twentieth century. The most thoroughly explored fields of application of organometallics were in the area of catalysis, asymmetric synthesis, olefin metathesis, as well as organic synthesis and access to new materials and polymers.The most usual ligands bound to d- and f-metals are carbon monoxide, phosphines, alkyls, carbenes and arenes, and in this review the bonding patterns in the metal carbonyls and ferrocene are elaborated. The common characteristics of these two classes are two-component bonds. The CO-M bonds include (i donation from ligand HOMO to vacant M d-orbitals (σ-bond, and (ii back-donation from the filled M d-orbitals in the ligand LUMO (π-bond. Similar (but much more complicated ferrocene contains delocalized bonds consisting of electron donation from Cp to Fe (σ-bonds- and π-bonding and δ-back-bonding from metal to Cp. In such a way ferrocene, i. e. (η5-Cp2Fe contains 18 bonding electrons giving to this compound "superaromatic" properties in the sense of stability and electrophilic substitution. In contrast to benzenoid aromatic compounds reactions in two Cp-rings can occur giving homo- and heteroannularly mono-, two-… per

  4. Protein carbonylation, protein aggregation and neuronal cell death in a murine model of multiple sclerosis

    Science.gov (United States)

    Dasgupta, Anushka

    Many studies have suggested that oxidative stress plays an important role in the pathophysiology of both multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Yet, the mechanism by which oxidative stress leads to tissue damage in these disorders is unclear. Recent work from our laboratory has revealed that protein carbonylation, a major oxidative modification caused by severe and/or chronic oxidative stress conditions, is elevated in MS and EAE. Furthermore, protein carbonylation has been shown to alter protein structure leading to misfolding/aggregation. These findings prompted me to hypothesize that carbonylated proteins, formed as a consequence of oxidative stress and/or decreased proteasomal activity, promote protein aggregation to mediate neuronal apoptosis in vitro and in EAE. To test this novel hypothesis, I first characterized protein carbonylation, protein aggregation and apoptosis along the spinal cord during the course of myelin-oligodendrocyte glycoprotein (MOG)35-55 peptide-induced EAE in C57BL/6 mice [Chapter 2]. The results show that carbonylated proteins accumulate throughout the course of the disease, albeit by different mechanisms: increased oxidative stress in acute EAE and decreased proteasomal activity in chronic EAE. I discovered not only that there is a temporal correlation between protein carbonylation and apoptosis but also that carbonyl levels are significantly higher in apoptotic cells. A high number of juxta-nuclear and cytoplasmic protein aggregates containing the majority of the oxidized proteins are also present during the course of EAE, which seems to be due to reduced autophagy. In chapter 3, I show that when gluthathione levels are reduced to those in EAE spinal cord, both neuron-like PC12 (nPC12) cells and primary neuronal cultures accumulate carbonylated proteins and undergo cell death (both by necrosis and apoptosis). Immunocytochemical and biochemical studies also revealed a temporal

  5. Crystal structure of quinone reductase 2 in complex with cancer prodrug CB1954.

    Science.gov (United States)

    Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao

    2005-10-14

    CB1954 is a cancer pro-drug that can be activated through reduction by Escherichia coli nitro-reductases and quinone reductases. Human quinone reductase 2 is very efficient in the activation of CB1954, approximately 3000 times more efficient than human QR1 in terms of k(cat)/K(m). We have solved the three-dimensional structure of QR2 in complex with CB1954 to a nominal resolution of 1.5A. The complex structure indicates the essentiality of the two nitro groups: one nitro group forms hydrogen bonds with the side-chain of Asn161 of QR2 to hold the other nitro group in position for the reduction. We further conclude that residue 161, an Asn in QR2 and a His in QR1, is critical in differentiating the substrate specificities of these two enzymes. Mutation of Asn161 to His161 in QR2 resulted in the total loss of the enzymatic activity towards activation of CB1954, whereas the rates of reduction towards menadione are not altered.

  6. Benchmarking of protein carbonylation analysis in Caenorhabditis elegans: specific considerations and general advice.

    Science.gov (United States)

    Pyr Dit Ruys, S; Bonzom, J-M; Frelon, S

    2016-10-01

    Oxidative stress has been extensively studied due to its correlation with cellular disorders and aging. In proteins, one biomarker of oxidative stress is the presence of carbonyl groups, such as aldehyde and ketone, in specific amino acid side chains such as lysine, proline, arginine and threonine, so-called protein carbonylation (PC). PC study is now a growing field in general and medical science since PC accumulation is associated with various pathologies and disorders. At present, enzyme-linked immunosorbent assays (ELISA) seem to be the most robust method of quantifying the presence of carbonyl groups in proteins, despite having some recognised caveats. In parallel, gel-based approaches present cross-comparison difficulties, along with other technical problems. As generic PC analyses still suffer from poor homogeneity, leading to cross-data analysis difficulties and poor results overlap, the need for harmonisation in the field of carbonyl detection is now widely accepted. This study aims to highlight some of the technical challenges in proteomic gel-based multiplexing experiments when dealing with PC in difficult samples like those from Caenorhabditis elegans, from protein extraction to carbonyl detection. We demonstrate that some critical technical parameters, such as labelling time, probe concentration, and total and carbonylated protein recovery rates, should be re-addressed in a sample-specific way. We also defined a procedure to cost-effectively adapt CyDye™-hydrazide-based protocols to specific samples, especially when the experimental interest is focused on studying differences between stimulating conditions with a maximised signal-to-noise ratio. Moreover, we have improved an already-existing powerful solubilisation buffer, making it potentially useful for hard-to-solubilise protein pellets. Lastly, the depicted methodology exemplifies a simple way of normalising carbonyl-related signal to total protein in SDS-PAGE multiplexing experiments. Within

  7. Inhibitor-bound complexes of dihydrofolate reductase-thymidylate synthase from Babesia bovis.

    Science.gov (United States)

    Begley, Darren W; Edwards, Thomas E; Raymond, Amy C; Smith, Eric R; Hartley, Robert C; Abendroth, Jan; Sankaran, Banumathi; Lorimer, Donald D; Myler, Peter J; Staker, Bart L; Stewart, Lance J

    2011-09-01

    Babesiosis is a tick-borne disease caused by eukaryotic Babesia parasites which are morphologically similar to Plasmodium falciparum, the causative agent of malaria in humans. Like Plasmodium, different species of Babesia are tuned to infect different mammalian hosts, including rats, dogs, horses and cattle. Most species of Plasmodium and Babesia possess an essential bifunctional enzyme for nucleotide synthesis and folate metabolism: dihydrofolate reductase-thymidylate synthase. Although thymidylate synthase is highly conserved across organisms, the bifunctional form of this enzyme is relatively uncommon in nature. The structural characterization of dihydrofolate reductase-thymidylate synthase in Babesia bovis, the causative agent of babesiosis in livestock cattle, is reported here. The apo state is compared with structures that contain dUMP, NADP and two different antifolate inhibitors: pemetrexed and raltitrexed. The complexes reveal modes of binding similar to that seen in drug-resistant malaria strains and point to the utility of applying structural studies with proven cancer chemotherapies towards infectious disease research.

  8. Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries.

    Science.gov (United States)

    Zhao, Qing; Zhu, Zhiqiang; Chen, Jun

    2017-12-01

    Organic carbonyl electrode materials that have the advantages of high capacity, low cost and being environmentally friendly, are regarded as powerful candidates for next-generation stationary and redox flow rechargeable batteries (RFBs). However, low carbonyl utilization, poor electronic conductivity and undesired dissolution in electrolyte are urgent issues to be solved. Here, we summarize a molecular engineering approach for tuning the capacity, working potential, concentration of active species, kinetics, and stability of stationary and redox flow batteries, which well resolves the problems of organic carbonyl electrode materials. As an example, in stationary batteries, 9,10-anthraquinone (AQ) with two carbonyls delivers a capacity of 257 mAh g -1 (2.27 V vs Li + /Li), while increasing the number of carbonyls to four with the formation of 5,7,12,14-pentacenetetrone results in a higher capacity of 317 mAh g -1 (2.60 V vs Li + /Li). In RFBs, AQ, which is less soluble in aqueous electrolyte, reaches 1 M by grafting -SO 3 H with the formation of 9,10-anthraquinone-2,7-disulphonic acid, resulting in a power density exceeding 0.6 W cm -2 with long cycling life. Therefore, through regulating substituent groups, conjugated structures, Coulomb interactions, and the molecular weight, the electrochemical performance of carbonyl electrode materials can be rationally optimized. This review offers fundamental principles and insight into designing advanced carbonyl materials for the electrodes of next-generation rechargeable batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Monodehydroascorbate reductase mediates TNT toxicity in plants.

    Science.gov (United States)

    Johnston, Emily J; Rylott, Elizabeth L; Beynon, Emily; Lorenz, Astrid; Chechik, Victor; Bruce, Neil C

    2015-09-04

    The explosive 2,4,6-trinitrotoluene (TNT) is a highly toxic and persistent environmental pollutant. Due to the scale of affected areas, one of the most cost-effective and environmentally friendly means of removing explosives pollution could be the use of plants. However, mechanisms of TNT phytotoxicity have been elusive. Here, we reveal that phytotoxicity is caused by reduction of TNT in the mitochondria, forming a nitro radical that reacts with atmospheric oxygen, generating reactive superoxide. The reaction is catalyzed by monodehydroascorbate reductase 6 (MDHAR6), with Arabidopsis deficient in MDHAR6 displaying enhanced TNT tolerance. This discovery will contribute toward the remediation of contaminated sites. Moreover, in an environment of increasing herbicide resistance, with a shortage in new herbicide classes, our findings reveal MDHAR6 as a valuable plant-specific target. Copyright © 2015, American Association for the Advancement of Science.

  10. Structures of mammalian cytosolic quinone reductases.

    Science.gov (United States)

    Foster, C E; Bianchet, M A; Talalay, P; Faig, M; Amzel, L M

    2000-08-01

    The metabolism of quinone compounds presents one source of oxidative stress in mammals, as many pathways proceed by mechanisms that generate reactive oxygen species as by-products. One defense against quinone toxicity is the enzyme NAD(P)H:quinone oxidoreductase type 1 (QR1), which metabolizes quinones by a two-electron reduction mechanism, thus averting production of radicals. QR1 is expressed in the cytoplasm of many tissues, and is highly inducible. A closely related homologue, quinone reductase type 2 (QR2), has been identified in several mammalian species. QR2 is also capable of reducing quinones to hydroquinones, but unlike QR1, cannot use NAD(P)H. X-ray crystallographic studies of QR1 and QR2 illustrate that despite their different biochemical properties, these enzymes have very similar three-dimensional structures. In particular, conserved features of the active sites point to the close relationship between these two enzymes.

  11. Enhancement of nitrate reductase activity by benzyladenine in Agrostemma githago

    Energy Technology Data Exchange (ETDEWEB)

    Kende, H.; Hahn, H.; Kays, S.E.

    1971-01-01

    Nitrate reductase activity in excised embryos of Agrostemma githago increases in response to both NO/sub 3//sup -/ and cytokinins. Discussed was whether cytokinins affected nitrate reductase activity directly or through NO/sub 3//sup -/, either by amplifying the effect of low endogenous NO/sub 3//sup -/ levels, or by making NO/sub 3//sup -/ available for induction from a metabolically inactive compartment. Nitrate reductase activity was enhanced on the average by 50% after 1 hour of benzyladenine treatment. In some experiments, the cytokinin response was detectable as early as 30 minutes after addition of benzyladenine. Nitrate reductase activity increased linearly for 4 hours and began to decay 13 hours after start of the hormone treatment. When embryos were incubated in solutions containing mixtures of NO/sub 3//sup -/ and benzyladenine, additive responses were obtained. The effects of NO/sub 3//sup -/ and benzyladenine were counteracted by abscisic acid. The increase in nitrate reductase activity was inhibited at lower abscisic acid concentrations in embryos which were induced with NO/sub 3//sup -/, as compared to embryos treated with benzyladenine. Casein hydrolysate inhibited the development of nitrate reductase activity. The response to NO/sub 3//sup -/ was more susceptible to inhibition by casein hydrolysate than the response to the hormone. When NO/sub 3//sup -/ and benzyladenine were withdrawn from the medium after maximal enhancement of nitrate reductase activity, the level of the enzyme decreased rapidly. Nitrate reductase activity increased again as a result of a second treatment with benzyladenine but not with NO/sub 3//sup -/. At the time of the second exposure to benzyladenine, no NO/sub 3//sup -/ was detectable in extracts of Agrostemma embryos. This is taken as evidence that cytokinins enhance nitrate reductase activity directly and not through induction by NO/sub 3//sup -/. 11 references, 5 figures, 3 tables.

  12. Proteomic quantification and identification of carbonylated proteins upon oxidative stress and during cellular aging.

    Science.gov (United States)

    Baraibar, Martin A; Ladouce, Romain; Friguet, Bertrand

    2013-10-30

    Increased protein carbonyl content is a hallmark of cellular and organismal aging. Protein damage leading to the formation of carbonyl groups derives from direct oxidation of several amino acid side chains but can also derive through protein adducts formation with lipid peroxidation products and dicarbonyl glycating compounds. All these modifications have been implicated during oxidative stress, aging and age-related diseases. However, in most cases, the proteins targeted by these deleterious modifications as well as their consequences have not yet been clearly identified. Indeed, this is essential to determine whether and how these modified proteins are impacting on cellular function, on the development of the senescent phenotype and the pathogenesis of age-related diseases. In this context, protein modifications occurring during aging and upon oxidative stress as well as main proteomic methods for detecting, quantifying and identifying oxidized proteins are described. Relevant proteomics studies aimed at monitoring the extent of protein carbonylation and identifying the targeted proteins in the context of aging and oxidative stress are also presented. Proteomics approaches, i.e. fluorescent based 2D-gel electrophoresis and mass spectrometry methods, represent powerful tools for monitoring at the proteome level the extent of protein oxidative and related modifications and for identifying the targeted proteins. Accumulation of damaged macromolecules, including oxidatively damaged (carbonylated) proteins, is a hallmark of cellular and organismal aging. Since protein carbonyls are the most commonly used markers of protein oxidation, different methods have been developed for the detection and quantification of carbonylated proteins. The identification of these protein targets is of valuable interest in order to understand the mechanisms by which damaged proteins accumulate and potentially affect cellular functions during oxidative stress, cellular senescence and

  13. Long-term In Vitro Treatment of Human Glioblastoma Cells with Temozolomide Increases Resistance In Vivo through Up-regulation of GLUT Transporter and Aldo-Keto Reductase Enzyme AKR1C Expression

    Directory of Open Access Journals (Sweden)

    Benjamin Le Calvé

    2010-09-01

    Full Text Available Glioblastoma (GBM is the most frequent malignant glioma. Treatment of GBM patients is multimodal with maximum surgical resection, followed by concurrent radiation and chemotherapy with the alkylating drug temozolomide (TMZ. The present study aims to identify genes implicated in the acquired resistance of two human GBM cells of astrocytic origin, T98G and U373, to TMZ. Resistance to TMZ was induced by culturing these cells in vitro for months with incremental TMZ concentrations up to 1 mM. Only partial resistance to TMZ has been achieved and was demonstrated in vivo in immunocompromised mice bearing orthotopic U373 and T98G xenografts. Our data show that long-term treatment of human astroglioma cells with TMZ induces increased expression of facilitative glucose transporter/solute carrier GLUT/SLC2A family members, mainly GLUT-3, and of the AKR1C family of proteins. The latter proteins are phase 1 drug-metabolizing enzymes involved in the maintenance of steroid homeostasis, prostaglandin metabolism, and metabolic activation of polycyclic aromatic hydrocarbons. GLUT-3 has been previously suggested to exert roles in GBM neovascularization processes, and TMZ was found to exert antiangiogenic effects in experimental gliomas. AKR1C1 was previously shown to be associated with oncogenic potential, with proproliferative effects similar to AKR1C3 in the latter case. Both AKR1C1 and AKR1C2 proteins are involved in cancer pro-proliferative cell chemoresistance. Selective targeting of GLUT-3 in GBM and/or AKR1C proteins (by means of jasmonates, for example could thus delay the acquisition of resistance to TMZ of astroglioma cells in the context of prolonged treatment with this drug.

  14. Iron dextran treatment does not induce serum protein carbonyls in the newborn pig.

    Science.gov (United States)

    Caperna, T J; Shannon, A E; Blomberg, L A; Garrett, W M; Ramsay, T G

    2012-01-01

    Oxidation of serum proteins can lead to carbonyl formation that alters their function and is often associated with stress-related diseases. As it is recommended that all pigs reared in modern production facilities be given supplemental iron at birth to prevent anemia, and metals can catalyze the carbonylation of proteins, the primary objective of this study was to determine whether standard iron dextran treatment was associated with enhanced serum protein oxidation in newborn piglets. Piglets were treated with 100 mg of iron dextran intramuscularly either on the day of birth, or on the third day after birth. Blood samples were collected from piglets 48 or 96 h after treatment and serum was harvested. For quantification, serum protein carbonyls were converted to hydrazones with dinitrophenyl hydrazine and analyzed spectrophotometrically. To identify and determine relative distribution of carbonylated proteins, serum protein carbonyls were derivatized with biotin hydrazide, separated by two-dimensional polyacrylamide gel electrophoresis, stained with avidin-fluorescein and identified by mass spectrometry. The standard iron dextran treatment was associated with no increase in total oxidized proteins if given either on the first or third day of life. In addition, with a few noted exceptions, the overall distribution and identification of oxidized proteins were similar between control and iron dextran-treated pigs. These results indicate that while iron dextran treatment is associated with a marked increase in circulating iron, it does not appear to specifically induce the oxidation of serum proteins.

  15. [Source profile of volatile carbonyl compounds in wastewater treatment plant of an oil refinery].

    Science.gov (United States)

    Zhou, Bo-Yu; Liu, Wang; Wang, Bo-Guang; Zhou, Mi; Huang, Qing; Zhou, Lei

    2013-07-01

    An observation was conducted at the wastewater treatment plant in a refinery in Guangdong province, using the PFPH-GC/MS method to analyze the composition and the concentration of volatile carbonyl compounds. The emission characteristics and the atmospheric chemical reactivity of these compounds were also studied. The results showed that 20 kinds of carbonyl compounds were detected with a concentration range of 0 to 68.80 microg x m(-3). The mean value of total concentration in all processing unit was (253.02 +/- 124.5) microg x m(-3). Background corrected concentrations showed that for each of the 6 treatment units of the plant, over 90% of the volatile carbonyl emissions were contributed by 14 of the 20 volatile carbonyl compounds, among which aldehyde was the most abundant with an average concentration of (44.74 +/- 20.89) microg x m(-3), followed by 2-butanone and acetaldehyde with average concentrations of (30.47 +/- 12.94) microg x m(-3) and (23.51 +/- 14.57) microg x m(-3), respectively. Several molecular markers were identified based on the analysis of the chemical activities and atmospheric lifetimes of the 20 carbonyl compounds. Finally, a source profile was established for the plant.

  16. Novel DNPH-based method for determination of protein carbonylation in muscle and meat.

    Science.gov (United States)

    Soglia, Francesca; Petracci, Massimiliano; Ertbjerg, Per

    2016-04-15

    Protein oxidation is considered an ongoing deteriorative process during storage of fresh and processed meat. Carbonyl compounds have traditionally been detected spectrophotometrically after derivatization with 2,4-dinitrophenylhydrazine (DNPH) to form protein-bound hydrazones with absorbance at 370 nm. Here we describe a novel DNPH-based method to quantify protein carbonylation in muscle and meat. The additional steps of the novel method aimed at increasing the protein solubility and inducing protein unfolding before labeling with DNPH. Compared to the traditional method, the new procedure reflected an increased protein carbonylation level measuring overall two to fourfold more carbonyls in muscles from different species as well as in soluble, salt-soluble and insoluble protein fractions. The study suggested that protein unfolding is a more important phenomenon than solubilization for increased DNPH labeling. The novel method resulted in three to fourfold larger carbonyl content determined in chicken, pork and beef (2.8, 3.6 and 3.1 nmol/mg of protein, respectively). Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Aldo-keto reductase 1B10 and its role in proliferation capacity of drug-resistant cancers

    Directory of Open Access Journals (Sweden)

    Toshiyuki eMatsunaga

    2012-01-01

    Full Text Available The human aldo-keto reductase AKR1B10, originally identified as an aldose reductase-like protein and human small intestine aldose reductase, is a cytosolic NADPH-dependent reductase that metabolizes a variety of endogenous compounds, such as aromatic and aliphatic aldehydes and dicarbonyl compounds, and some drug ketones. The enzyme is highly expressed in solid tumors of several tissues including lung and liver, and as such has received considerable interest as a relevant biomarker for the development of those tumors. In addition, AKR1B10 has been recently reported to be significantly up-regulated in some cancer cell lines (medulloblastoma D341 and colon cancer HT29 acquiring resistance towards chemotherapeutic agents (cyclophosphamide and mitomycin c, suggesting the validity of the enzyme as a chemoresistance marker. Although the detailed information on the AKR1B10-mediated mechanisms leading to the drug resistance process is not well understood so far, the enzyme has been proposed to be involved in functional regulations of cell proliferation and metabolism of drugs and endogenous lipids during the development of chemoresistance. This article reviews the current literature focusing mainly on expression profile and roles of AKR1B10 in the drug resistance of cancer cells. Recent developments of AKR1B10 inhibitors and their usefulness in restoring sensitivity to anticancer drugs are also reviewed.

  18. Carbonyl compounds at Mount Tai in the North China Plain: Characteristics, sources, and effects on ozone formation

    Science.gov (United States)

    Yang, Xue; Xue, Likun; Yao, Lan; Li, Qinyi; Wen, Liang; Zhu, Yanhong; Chen, Tianshu; Wang, Xinfeng; Yang, Lingxiao; Wang, Tao; Lee, Shuncheng; Chen, Jianmin; Wang, Wenxing

    2017-11-01

    Carbonyl compounds, an important category of volatile organic compounds (VOCs), play important roles in ozone (O3) formation and atmospheric chemistry. To better understand the characteristics and sources of carbonyl compounds and their effects on O3 formation, C1-C8 carbonyls were measured at Mount Tai, the highest mountain in the North China Plain (NCP), in summer 2014. Acetone (3.57 ± 0.55 ppbv), formaldehyde (3.48 ± 0.98 ppbv) and acetaldehyde (1.27 ± 0.78 ppbv) are the three most abundant species, comprising as high as 90% of the total observed compounds. Isovaleraldehyde (0.37 ± 0.17 ppbv) presents another important carbonyl compound despite its high reactivity. Comparison with the observations available in China highlights the serious situation of carbonyls pollution in the NCP region. The sources of carbonyls are dominated by photo-oxidation of VOCs during the daytime and regional transport at night. Secondary sources from oxidation of hydrocarbons contribute on average 44% of formaldehyde, 31% of acetone, 85% of acetaldehyde, 78% of benzaldehyde, and 84% of isovaleraldehyde, demonstrating the dominant role of secondary formation in the ambient carbonyl levels. Formaldehyde, acetaldehyde and isovaleraldehyde are the most important contributors to the OH reactivity and O3 production among the measured carbonyls. This study shows that carbonyl compounds contribute significantly to the photochemical pollution in the NCP region and hence understanding their sources and characteristics is essential for developing the science-based O3 pollution control strategies.

  19. Antioxidative potential of Perna viridis and its protective role against ROS induced lipidperoxidation and protein carbonyl

    Digital Repository Service at National Institute of Oceanography (India)

    Jena, K.B.; Jagtap, T.G.; Verlecar, X.N.

    systems, ROS are balanced at physiological concentrations by varieties of antioxidants, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), reduced glutathione (GSH...

  20. Expression of steroid 5α-reductase isozymes in prostate of adult rats after environmental stress.

    Science.gov (United States)

    Sánchez, Pilar; Torres, Jesús M; Castro, Beatriz; Olmo, Asunción; del Moral, Raimundo G; Ortega, Esperanza

    2013-01-01

    The elevated incidence of prostate cancer and benign prostatic hypertrophy is a cause of increasing public health concern in the Western world. The normal and pathological growth of the prostate are both dependent on stimulation by dihydrotestosterone, which is synthesized from circulating testosterone by two 5α-reductase (5α-R) isozymes, 5α-reductase type 1 (5α-R1) and 5α-reductase type 2 (5α-R2). Both isozymes have been implicated in prostate disease. We used quantitative RT-PCR and immunohistochemistry, respectively, to quantify mRNA and protein levels of 5α-R isozymes in the ventral prostate of adult rats under environmental stress conditions analogous to those found in some common workplace situations, i.e. artificial light, excessive heat, and the sensation of immobility in a small space. Transcription and expression levels of both 5α-R isozymes were significantly higher in environmentally stressed rats than in unstressed rats. Increased 5α-R isozyme levels may play a role in the development or maintenance of prostate disease. Further research is warranted to explore these effects of environmental stress on human health and their implications for environmental and occupational health policies. © 2012 The Authors Journal compilation © 2012 FEBS.

  1. Modulating the molybdenum coordination sphere of Escherichia coli trimethylamine N-oxide reductase.

    Science.gov (United States)

    Kaufmann, Paul; Duffus, Benjamin R; Mitrova, Biljana; Iobbi-Nivol, Chantal; Teutloff, Christian; Nimtz, Manfred; Jänsch, Lothar; Wollenberger, Ulla; Leimkühler, Silke

    2018-01-15

    The well-studied enterobacterium Escherichia coli present in the human gut is able to reduce TMAO to trimethylamine (TMA) during anaerobic respiration. The TMAO reductase TorA is a monomeric, bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor-containing enzyme belonging to the dimethylsulfoxide (DMSO) reductase family of molybdoenzymes. We report on a system for the in vitro reconstitution of TorA with molybdenum cofactors (Moco) from different sources. Higher TMAO reductase activities for TorA were obtained when using Moco-sources containing a sulfido ligand at the molybdenum atom. For the first time, we were able to isolate functional bis-MGD from Rhodobacter capsulatus formate dehydrogenase (FDH), which remained intact in its isolated state and after insertion into apo-TorA yielded a highly active enzyme. Combined characterizations of the reconstituted TorA enzymes by EPR spectroscopy and direct electrochemistry emphasize that TorA activity can be modified by changes in the Mo-coordination sphere. The combination of these results together with studies on amino acid exchanges at the active site led us to propose a novel model for substrate binding to the molybdenum atom of TorA.

  2. Inhibition of 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase (Ex Vivo by Morus indica (Mulberry

    Directory of Open Access Journals (Sweden)

    Vanitha Reddy Palvai

    2014-01-01

    Full Text Available Phytochemicals are the bioactive components that contribute to the prevention of cardiovascular and other degenerative diseases. Inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA reductase would be an effective means of lowering plasma cholesterol in humans. The present study explores the HMG CoA reductase inhibitory effect of extracts from leaves of Morus indica varieties, M5, V1, and S36, compared with the statin, using an ex vivo method. The assay is based on the stoichiometric formation of coenzyme A during the reduction of microsomal HMG CoA to mevalonate. Dechlorophyllised extract of three varieties was studied at 300 µg. The coenzyme A released at the end of assay in control (100.31 nmoles and statins (94.46 nm was higher than the dechlorphyllised extracts of the samples. The coenzyme A released during the reduction of HMG CoA to mevalonate in dechlorophyllised extracts of the samples was as follows: S36 < M5 < V1. The results indicated that the samples were highly effective in inhibiting the enzyme compared to statins (standard drug. The results indicate the role of Morus varieties extracts in modulating the cholesterol metabolism by inhibiting the activity of HMG CoA reductase. These results provide scope for designing in vivo animal studies to confirm their effect.

  3. Aldose Reductase Inhibitory Activity of Compounds from  Zea mays L.

    Science.gov (United States)

    Kim, Tae Hyeon; Kim, Jin Kyu; Kang, Young-Hee; Lee, Jae-Yong; Kang, Il Jun; Lim, Soon Sung

    2013-01-01

    Aldose reductase (AR) inhibitors have a considerable therapeutic potential against diabetes complications and do not increase the risk of hypoglycemia. Through bioassay-guided fractionation of an EtOH extract of the kernel from purple corn (Zea mays L.), 7 nonanthocyanin phenolic compounds (compound 1–7) and 5 anthocyanins (compound 8–12) were isolated. These compounds were investigated by rat lens aldose reductase (RLAR) inhibitory assays. Kinetic analyses of recombinant human aldose reductase (rhAR) were performed, and intracellular galactitol levels were measured. Hirsutrin, one of 12 isolated compounds, showed the most potent RLAR inhibitory activity (IC50, 4.78 μM). In the kinetic analyses using Lineweaver-Burk plots of 1/velocity and 1/substrate concentration, hirsutrin showed competitive inhibition against rhAR. Furthermore, hirsutrin inhibited galactitol formation in rat lens and erythrocytes sample incubated with a high concentration of galactose; this finding indicates that hirsutrin may effectively prevent osmotic stress in hyperglycemia. Therefore, hirsutrin derived from Zea mays L. may be a potential therapeutic agent against diabetes complications. PMID:23586057

  4. Light Sensitivity of Lactococcus lactis Thioredoxin Reductase

    DEFF Research Database (Denmark)

    Skjoldager, Nicklas

    system is an alternative thiol-based antioxidant system, but the glutathione biosynthesis system is not present in all organisms. This thesis focuses on the TrxR from the lactic acid bacteria (LAB) model organism Lactococcus lactis ssp. cremoris MG1363, a strain that is glutathione- and catalasenegative...... with a shift in the absorbance spectrum of the tightly bound FAD co-enzyme and oxidation of the methyl group of the isoalloxazine ring, as determined by MS. The extracted FAD from photo-inactivated LlTrxR also displayed a positive result in a dinitrophenylhydrazine (DNPH) test, indicating the presence...... of a carbonyl group, i. e. an aldehyde. LlTrxR reduces O2 in the presence of NADPH faster than the EcTrxR and the photo-inactivation is lowered at semi-anaerobic conditions and in the presence of iodine a well-known quencher of photoexcited triplet state flavin. The present PhD study was initiated in order...

  5. Synthesis, induced-fit docking investigations, and in vitro aldose reductase inhibitory activity of non-carboxylic acid containing 2,4-thiazolidinedione derivatives.

    Science.gov (United States)

    Maccari, Rosanna; Ottanà, Rosaria; Ciurleo, Rosella; Rakowitz, Dietmar; Matuszczak, Barbara; Laggner, Christian; Langer, Thierry

    2008-06-01

    In continuation of our studies, we here report a series of non-carboxylic acid containing 2,4-thiazolidinedione derivatives, analogues of previously synthesized carboxylic acids which we had found to be very active in vitro aldose reductase (ALR2) inhibitors. Although the replacement of the carboxylic group with the carboxamide or N-hydroxycarboxamide one decreased the in vitro ALR2 inhibitory effect, this led to the identification of mainly non-ionized derivatives with micromolar ALR2 affinity. The 5-arylidene moiety deeply influenced the activity of these 2,4-thiazolidinediones. Our induced-fit docking studies suggested that 5-(4-hydroxybenzylidene)-substituted derivatives may bind the polar recognition region of the ALR2 active site by means of the deprotonated phenol group, while their acetic chain and carbonyl group at position 2 of the thiazolidinedione ring form a tight net of hydrogen bonds with amino acid residues of the lipophilic specificity pocket of the enzyme.

  6. [Fumarate reductase in the mitochondria of the trematode Calicophoron ijimai].

    Science.gov (United States)

    Iarygina, G V; Vykhrestiuk, N P; Burenina, E A

    1983-01-01

    The presence of active fumarate reductase system in mitochondria of the trematode Calicophoron ijimai was shown. Fumarate reductase activities in different collections of C. ijimai vary considerably. Maximum activity accounts for 47.7 +/- 1.0 nM/min/mg protein whereas minimum--for 15.1 +/- 0.1. Some properties of the enzyme were studied. The effect of thiabendazole, bitionol, oxinid and preparations of G-1026 and G-937 on the fumarate reductase activity was investigated. G-1026, G-937 preparations and bitionol have the strongest inhibitory effect on the enzyme. Thiabendazole inhibited but little the fumarate reductase reaction in C. ijimai. The enzyme activity was not affected by oxinid.

  7. Regulation of ribonucleotide reductase by Spd1 involves multiple mechanisms

    DEFF Research Database (Denmark)

    Nestoras, Konstantinos; Mohammed, Asma Hadi; Schreurs, Ann-Sofie

    2010-01-01

    The correct levels of deoxyribonucleotide triphosphates and their relative abundance are important to maintain genomic integrity. Ribonucleotide reductase (RNR) regulation is complex and multifaceted. RNR is regulated allosterically by two nucleotide-binding sites, by transcriptional control, and...

  8. Reduction of Folate by Dihydrofolate Reductase from Thermotoga maritima

    NARCIS (Netherlands)

    Loveridge, E Joel; Hroch, Lukas; Hughes, Robert L; Williams, Thomas; Davies, Rhidian L; Angelastro, Antonio; Luk, Louis Y P; Maglia, Giovanni; Allemann, Rudolf K

    2017-01-01

    Mammalian dihydrofolate reductases (DHFR) catalyse the reduction of folate more efficiently than the equivalent bacterial enzymes, despite typically having similar efficiencies for the reduction of their natural substrate dihydrofolate. In contrast, we show here that DHFR from the hyperthermophilic

  9. Potency of a novel saw palmetto ethanol extract, SPET-085, for inhibition of 5alpha-reductase II.

    Science.gov (United States)

    Pais, Pilar

    2010-08-01

    The nicotinamide adenine dinucleotide phosphate (NADPH)-dependent membrane protein 5alpha-reductase irreversibly catalyses the conversion of testosterone to the most potent androgen, 5alpha-dihydrotestosterone (DHT). In humans, two 5alpha-reductase isoenyzmes are expressed: type I and type II. Type II is found primarily in prostate tissue. Saw palmetto extract (SPE) has been widely used for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia (BPH). The mechanisms of the pharmacological effects of SPE include the inhibition of 5alpha-reductase, among other actions. Clinical studies of SPE have been equivocal, with some showing significant results and others not. These inconsistent results may be due, in part, to varying bioactivities of the SPE used in the studies. The aim of the present study was to determine the in vitro potency of a novel saw palmetto ethanol extract (SPET-085), an inhibitor of the 5alpha-reductase isoenzyme type II, in a cell-free test system. On the basis of the enzymatic conversion of the substrate androstenedione to the 5alpha-reduced product 5alpha-androstanedione, the inhibitory potency was measured and compared to those of finasteride, an approved 5alpha-reductase inhibitor. SPET-085 concentration-dependently inhibited 5alpha-reductase type II in vitro (IC(50)=2.88+/-0.45 microg/mL). The approved 5alpha-reductase inhibitor, finasteride, tested as positive control, led to 61% inhibition of 5alpha-reductase type II. SPET-085 effectively inhibits the enzyme that has been linked to BPH, and the amount of extract required for activity is very low compared to data reported for other extracts. It can be concluded from data in the literature that SPET-085 is as effective as a hexane extract of saw palmetto that exhibited the highest levels of bioactivity, and is more effective than other SPEs tested. This study confirmed that SPET-085 has prostate health-promoting bioactivity that also corresponds favorably to

  10. Influence of the Dielectric Medium on the Carbonyl Infrared Absorption Peak of Acetylferrocene

    Directory of Open Access Journals (Sweden)

    F. López-Linares

    2005-02-01

    Full Text Available The solvent effect on the position of the carbonyl vibrational stretching ofacetylferrocene in aprotic media was studied in this work. The solvent-induced shifts in thisorganometallic compound were interpreted in terms of the alternative reaction field model(SCRF-MO proposed by Kolling. In contrast to the established trends for carbonyl groupsin organic systems, the results suggest that the continuum models for the reaction field arenot adequate and that the influence of dipolarity-polarizability described by aninhomogeneous coupling function θ (ε L(n 2 that assumes optical dielectric saturation isresponsible for the carbonyl band shift and, there is empirical evidence that the effect offield-induced intermolecular interaction on band shift, interpreted in terms of the van derWaals forces from the solvent, have a important contribution to this phenomena.

  11. Determination of protein carbonyls in plasma, cell extracts, tissue homogenates, isolated proteins

    DEFF Research Database (Denmark)

    Weber, Daniela; Davies, Michael J.; Grune, Tilman

    2015-01-01

    Protein oxidation is involved in regulatory physiological events as well as in damage to tissues and is thought to play a key role in the pathophysiology of diseases and in the aging process. Protein-bound carbonyls represent a marker of global protein oxidation, as they are generated by multiple...... in the most relevant methods to detect protein carbonyls after derivatization with 2,4-dinitrophenylhydrazine with an emphasis on measurement in plasma, cells, organ homogenates, isolated proteins and organelles. Sample preparation, derivatization conditions and protein handling are presented...... for the spectrophotometric and HPLC method as well as for immunoblotting and ELISA. An extensive overview covering these methods in previously published articles is given for researchers who plan to measure protein carbonyls in different samples....

  12. Effect of carbonyl iron particles composition on the physical characteristics of MR grease

    Energy Technology Data Exchange (ETDEWEB)

    Mohamad, Norzilawati, E-mail: mnorzilawati@gmail.com; Mazlan, Saiful Amri, E-mail: amri.kl@utm.my [Vehicle System Engineering, Malaysia – Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra (Jalan Semarak), Kuala Lumpur, 54000 (Malaysia); Ubaidillah, E-mail: ubaidillah@uns.ac.id [Vehicle System Engineering, Malaysia – Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra (Jalan Semarak), Kuala Lumpur, 54000 (Malaysia); Mechanical Engineering Department, Faculty of Engineering, Universitas Sebelas Maret, Jl. Ir. Sutami 36A, Kentingan, Surakarta, 57126, Central Java, Surakarta (Indonesia)

    2016-03-29

    Magnetorheological (MR) grease is an extension of the study of magnetorheological materials. The MR grease can help to reduce the particles sedimentation problem occurred in the MR fluids. Within this study, an effort has been taken to investigate the effect of different weight compositions of carbonyl iron particles on the physical and chemical characteristics of the MR grease under off-state condition (no magnetic field). The MR grease is prepared by mixing carbonyl iron particles having a size range of 1 to 10 µm with commercial NPC Highrex HD-3 grease. Characterizations of MR grease are investigated using Vibrating Sample Magnetometer (VSM), Environmental Scanning Electron Microscopy (ESEM), Differential Scanning Calorimeter (DSC) and rheometer. The dependency of carbonyl iron particles weight towards the magnetic properties of MR grease and other characterizations are investigated.

  13. Carbonyl compounds and dissolved organic carbon in rainwater of an urban atmosphere.

    Science.gov (United States)

    Balla, D; Papageorgiou, A; Voutsa, D

    2014-10-01

    This study investigates the occurrence of carbonyl compounds in rainwater at the city of Thessaloniki, Northern Greece. The concentrations of carbonyl compounds (as sum of 14 compounds) ranged from 21.8 to 592 μg/L, mean concentration 119 μg/L. Formaldehyde, acetaldehyde, hexanal, glyoxal, and methylglyoxal were the dominant compounds. DOC concentrations in rainwater ranged from 0.46 to 21.3 mg/L. UV-Vis and fluorescence spectra characteristics showed variation among rain events. Carbonyl compounds were negatively correlated with temperature exhibited relatively higher concentrations in cold season. They also influenced by storm origin with higher concentrations under terrestrial air masses. Calm conditions enhance the concentrations of DOC. Wash out is an effective removal mechanism of DOC.

  14. Tissue thioredoxin reductase-1 expression in astrocytomas of different grades.

    Science.gov (United States)

    Esen, Hasan; Erdi, Fatih; Kaya, Bulent; Feyzioglu, Bahadır; Keskin, Fatih; Demir, Lutfi Saltuk

    2015-02-01

    Thioredoxin (Trx) is a redox active protein that regulates several physiological and biochemical functions, such as growth, apoptosis and cellular defense. The function of Trx itself is regulated by thioredoxin reductase (TrxR). Studies performed in a variety of human primary tumors have shown that thioredoxin reductase 1 (TrxR1) is overexpressed in tumoral tissues compared with corresponding normal tissues. This study was designed to determine the expression of TrxR1 in astrocytoma tissues of different World Health Organization (WHO) grades (grade I-IV). The proliferative (Ki-67) and apoptotic indices of the specimens were also investigated for correlation analysis. Astrocytoma tissues were extracted from the histopathological specimens of 40 patients. These samples included seven histologically normal brain tissues that served as a control group and ten tumoral samples for each grade of astrocytoma (grade I-IV). The histologically normal brain tissues were obtained from the non-tumoral portions of the pathological specimens of grade I (2 cases), grade II (2 cases), grade III (2 cases) and grade IV (1 case) astrocytomas. TrxR1 expression was evaluated using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunostaining. The proliferative and apoptotic indices of the specimens were investigated by Ki-67 immunostaining and TUNEL assay, respectively. TrxR1 expression, as assessed by qRT-PCR, increased significantly with astrocytoma grade (p = 0.01). The immunostaining intensity of TrxR1 in grade IV astrocytomas was significantly greater than that in the control tissue and all other astrocytoma grades (p grade III astrocytomas was significantly greater than that in the control group and grade I astrocytomas (p grades, but the differences between grade I and the control, grade II and the control, grades II and I, grades III and II were not statistically significant (p > 0.05). Ki-67 index values increased significant in accordance with grade

  15. A second target of benzamide riboside: dihydrofolate reductase.

    Science.gov (United States)

    Roussel, Breton; Johnson-Farley, Nadine; Kerrigan, John E; Scotto, Kathleen W; Banerjee, Debabrata; Felczak, Krzysztof; Pankiewicz, Krzysztof W; Gounder, Murugesan; Lin, HongXia; Abali, Emine Ercikan; Bertino, Joseph R

    2012-11-01

    Dihydrofolate reductase (DHFR) is an essential enzyme involved in de novo purine and thymidine biosynthesis. For several decades, selective inhibition of DHFR has proven to be a potent therapeutic approach in the treatment of various cancers including acute lymphoblastic leukemia, non-Hodgkin's lymphoma, osteogenic sarcoma, carcinoma of the breast, and head and neck cancer. Therapeutic success with DHFR inhibitor methotrexate (MTX) has been compromised in the clinic, which limits the success of MTX treatment by both acquired and intrinsic resistance mechanisms. We report that benzamide riboside (BR), via anabolism to benzamide adenine dinucleotide (BAD) known to potently inhibit inosine monophosphate dehydrogenase (IMPDH), also inhibits cell growth through a mechanism involving downregulation of DHFR protein. Evidence to support this second site of action of BR includes the finding that CCRF-CEM/R human T-cell lymphoblasic leukemia cells, resistant to MTX as a consequence of gene amplification and overexpression of DHFR, are more resistant to BR than are parental cells. Studies of the mechanism by which BR lowers DHFR showed that BR, through its metabolite BAD, reduced NADP and NADPH cellular levels by inhibiting nicotinamide adenine dinucleotide kinase (NADK). As consequence of the lack of NADPH, DHFR was shown to be destabilized. We suggest that, inhibition of NADK is a new approach to downregulate DHFR and to inhibit cell growth.

  16. Methylenetetrahydrofolate reductase (MTHFR) deficiency enhances resistance against cytomegalovirus infection.

    Science.gov (United States)

    Fodil-Cornu, N; Kozij, N; Wu, Q; Rozen, R; Vidal, S M

    2009-10-01

    Folates provide one-carbon units for nucleotide synthesis and methylation reactions. A common polymorphism in the MTHFR gene (677C --> T) results in reduced enzymatic activity, and is associated with an increased risk for neural tube defects and cardiovascular disease. The high prevalence of this polymorphism suggests that it may have experienced a selective advantage under environmental pressure, possibly an infectious agent. To test the hypothesis that methylenetetrahydrofolate reductase (MTHFR) genotype influences the outcome of infectious disease, we examined the response of Mthfr-deficient mice against mouse cytomegalovirus (MCMV) infection. Acute MCMV infection of Mthfr(-/-) mice resulted in early control of cytokine secretion, decreased viral titer and preservation of spleen immune cells, in contrast to Mthfr wild-type littermates. The phenotype was abolished in MTHFR transgenic mice carrying an extra copy of the gene. Infection of primary fibroblasts with MCMV showed a decrease in viral replication and in the number of productively infected cells in Mthfr(+/-) fibroblasts compared with wild-type cells. These results indicate that Mthfr deficiency protects against MCMV infection in vivo and in vitro, suggesting that human genetic variants may provide an advantage in the host response against certain pathogens.

  17. Cryopreservation of bull semen is associated with carbonylation of sperm proteins.

    Science.gov (United States)

    Mostek, Agnieszka; Dietrich, Mariola Aleksandra; Słowińska, Mariola; Ciereszko, Andrzej

    2017-04-01

    Artificial insemination with cryopreserved semen enables affordable, large-scale dissemination of gametes with superior genetics. However, cryopreservation can cause functional and structural damage to spermatozoa that is associated with reactive oxygen species (ROS) production, impairment of sperm motility and decreased fertilizing potential, but little attention has been paid to protein changes. The goal of this study was to investigate the oxidative modifications (measured as carbonylation level changes) of bull spermatozoa proteins triggered by the cryopreservation process. Flow cytometry and computer-assisted sperm analysis were used to evaluate changes in viability, ROS level and motility of spermatozoa. Western blotting, in conjunction with two-dimensional electrophoresis (2D-oxyblot) and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight spectrometry, was employed to identify and quantify the specifically carbonylated spermatozoa proteins. Cryopreservation decreased motility and viability but increased the number of ROS-positive cells. We identified 11 proteins (ropporin-1, outer dense fiber protein 2, glutathione S-transferase, triosephosphate isomerase, capping protein beta 3 isoform, actin-related protein M1, actin-related protein T2, NADH dehydrogenase, isocitrate dehydrogenase, cilia- and flagella-associated protein 161, phosphatidylethanolamine-binding protein 4) showing differences in protein carbonylation in response to cryopreservation. The identified proteins are associated with cytoskeleton and flagella organization, detoxification and energy metabolism. Moreover, almost all of the identified carbonylated proteins are involved in capacitation. Our results indicate for the first time that cryopreservation induces oxidation of selected sperm proteins via carbonylation. We suggest that carbonylation of sperm proteins could be a direct result of oxidative stress and potentially lead to disturbances of capacitation

  18. Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl-Olefin Metathesis.

    Science.gov (United States)

    McAtee, Christopher C; Riehl, Paul S; Schindler, Corinna S

    2017-03-01

    Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl-olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl3 as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl-olefin ring-closing metathesis has been obtained.

  19. First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation

    DEFF Research Database (Denmark)

    Riisager, Anders; Jørgensen, Betina; Wasserscheid, Peter

    2006-01-01

    A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation.......A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)(2)I-2]-[BMIM]I -SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation....

  20. Contribution of carbonyl photochemistry to aging of atmospheric secondary organic aerosol

    DEFF Research Database (Denmark)

    Mang, Stephen A.; Henricksen, Dana K.; Bateman, Adam P.

    2008-01-01

    The photodegradation of secondary organic aerosol (SOA) material by actinic UV radiation was investigated. SOA was generated via the dark reaction of ozone and d-limonene, collected onto quartz-fiber filters, and exposed to wavelength-tunable radiation. Photochemical production of CO was monitored...... was measured and compared with the photolysis action spectrum for the release of CO, a marker for Norrish type-1 photocleavage of carbonyls. Both spectra had a band at similar to 300 nm corresponding to the overlapping n -> pi* transitions in nonconjugated carbonyls. The effective extinction coefficient...

  1. Impaired cardiac SIRT1 activity by carbonyl stress contributes to aging-related ischemic intolerance.

    Directory of Open Access Journals (Sweden)

    Chunhu Gu

    Full Text Available Reactive aldehydes can initiate protein oxidative damage which may contribute to heart senescence. Sirtuin 1 (SIRT1 is considered to be a potential interventional target for I/R injury management in the elderly. We hypothesized that aldehyde mediated carbonyl stress increases susceptibility of aged hearts to ischemia/reperfusion (I/R injury, and elucidate the underlying mechanisms with a focus on SIRT1. Male C57BL/6 young (4-6 mo and aged (22-24 mo mice were subjected to myocardial I/R. Cardiac aldehyde dehydrogenase (ALDH2, SIRT1 activity and protein carbonyls were assessed. Our data revealed that aged heart exhibited increased endogenous aldehyde/carbonyl stress due to impaired ALDH2 activity concomitant with blunted SIRT1 activity (P<0.05. Exogenous toxic aldehydes (4-HNE exposure in isolated cardiomyocyte verified that aldehyde-induced carbonyl modification on SIRT1 impaired SIRT1 activity leading to worse hypoxia/reoxygenation (H/R injury, which could all be rescued by Alda-1 (ALDH2 activator (all P<0.05. However, SIRT1 inhibitor blocked the protective effect of Alda-1 on H/R cardiomyocyte. Interestingly, myocardial I/R leads to higher carbonylation but lower activity of SIRT1 in aged hearts than that seen in young hearts (P<0.05. The application of Alda-1 significantly reduced the carbonylation on SIRT1 and markedly improved the tolerance to in vivo I/R injury in aged hearts, but failed to protect Sirt1(+/- knockout mice against myocardial I/R injury. This was verified by Alda-1 treatment improved postischemic contractile function recovery in ex vivo perfused aged but not in Sirt1(+/- hearts. Thus, aldehyde/carbonyl stress is accelerated in aging heart. These results provide a new insight that impaired cardiac SIRT1 activity by carbonyl stress plays a critical role in the increased susceptibility of aged heart to I/R injury. ALDH2 activation can restore this aging-related myocardial ischemic intolerance.

  2. Photophysical properties of a synthetic, carbonyl-containing (N=6+CO) carotenoid analogue

    Energy Technology Data Exchange (ETDEWEB)

    Niedzwiedzki, Dariusz M. [Washington Univ., St. Louis, MO (United States)

    2014-05-01

    Retinyl-1 is a synthetic carotenoid analogue belonging to the retinal analogues family. It has six conjugated carbon–carbon double bonds with a carbonyl group conjugated to the π-electron system. Presence of the carbonyl group in vicinity of the conjugated carbon–carbon backbone leads to unique excited state properties that are extremely sensitive to solvent polarity and temperature. The simplicity of the synthesis of Retinyl-1 and ease of attachment to synthetic tetrapyrrole chromophores make Retinyl-1 attractive for use in artificial photosynthetic systems.

  3. Inactivation of cellular enzymes by carbonyls and protein-bound glycation/glycoxidation products

    DEFF Research Database (Denmark)

    Morgan, Philip E; Dean, Roger T; Davies, Michael Jonathan

    2002-01-01

    dismutase, or catalase dependent, suggesting that inhibition is not radical mediated. These effects are suggested to be due to direct adduction of the free- or protein-bound carbonyls with the target enzyme. Such an interpretation is supported by the detection of the loss of thiol groups on GAPDH...... and the detection of cross-linked materials on protein gels. Though direct comparison of the extent of inhibition induced by free versus protein-bound carbonyls was not possible, the significantly higher concentrations of the latter materials over the former in diabetic plasma and cells lead us to suggest...

  4. Selective Palladium(II)-Catalyzed Carbonylation of Methylene β-C-H Bonds in Aliphatic Amines.

    OpenAIRE

    Cabrera-Pardo, Jaime R; Trowbridge, Aaron; Nappi, Manuel; Ozaki, Kyohei; Gaunt, Matthew James

    2017-01-01

    Pd(II)-catalyzed C–H carbonylation of methylene C–H bonds in secondary aliphatic amines leads to the formation trans-disubstituted β-lactams in excellent yields and selectivities. The generality of the C–H carbonylation process is aided by the action of xantphos-based ligands and is important in securing good yields of the β-lactam products. EPSRC (EP/100548X/1), ERC (ERC-STG-259711), Royal Society (Wolfson Award), Marie Curie Foundation and Herchel Smith Foundation.

  5. 1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides with Carbonyl Dipolarophiles Yielding Oxazolidine Derivatives

    Directory of Open Access Journals (Sweden)

    Adam G. Meyer

    2016-07-01

    Full Text Available We provide a comprehensive account of the 1,3-dipolar cycloaddition reactions of azomethine ylides with carbonyl dipolarophiles. Many different azomethine ylides have been studied, including stabilized and non-stabilized ylides. Of the carbonyl dipolarophiles, aldehydes including formaldehyde are the most studied, although there are now examples of cycloadditions with ketones, ketenes and carboxyl systems, in particular isatoic anhydrides and phthalic anhydrides. Intramolecular cycloadditions with esters can also occur under certain circumstances. The oxazolidine cycloadducts undergo a range of reactions triggered by the ring-opening of the oxazolidine ring system.

  6. Aldose reductase mediates retinal microglia activation

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Kun-Che; Shieh, Biehuoy; Petrash, J. Mark, E-mail: mark.petrash@ucdenver.edu

    2016-04-29

    Retinal microglia (RMG) are one of the major immune cells in charge of surveillance of inflammatory responses in the eye. In the absence of an inflammatory stimulus, RMG reside predominately in the ganglion layer and inner or outer plexiform layers. However, under stress RMG become activated and migrate into the inner nuclear layer (INL) or outer nuclear layer (ONL). Activated RMG in cell culture secrete pro-inflammatory cytokines in a manner sensitive to downregulation by aldose reductase inhibitors. In this study, we utilized CX3CR1{sup GFP} mice carrying AR mutant alleles to evaluate the role of AR on RMG activation and migration in vivo. When tested on an AR{sup WT} background, IP injection of LPS induced RMG activation and migration into the INL and ONL. However, this phenomenon was largely prevented by AR inhibitors or in AR null mice, or was exacerbated in transgenic mice that over-express AR. LPS-induced increases in ocular levels of TNF-α and CX3CL-1 in WT mice were substantially lower in AR null mice or were reduced by AR inhibitor treatment. These studies demonstrate that AR expression in RMG may contribute to the proinflammatory phenotypes common to various eye diseases such as uveitis and diabetic retinopathy. - Highlights: • AR inhibition prevents retinal microglial activation. • Endotoxin-induced ocular cytokine production is reduced in AR null mice. • Overexpression of AR spontaneously induces retinal microglial activation.

  7. Evaluation of constitutive iron reductase (AtFRO2 expression on mineral accumulation and distribution in soybean (Glycine max. L

    Directory of Open Access Journals (Sweden)

    Marta Wilton Vasconcelos

    2014-04-01

    Full Text Available Iron is an important micronutrient in human and plant nutrition. Adequate iron nutrition during crop production is central for assuring appropriate iron concentrations in the harvestable organs, for human food or animal feed. The whole-plant movement of iron involves several processes, including the reduction of ferric to ferrous iron at several locations throughout the plant, prior to transmembrane trafficking of ferrous iron. In this study, soybean plants that constitutively expressed the AtFRO2 iron reductase gene were analyzed for leaf iron reductase activity, as well as the effect of this transgene's expression on root, leaf, pod wall, and seed mineral concentrations. High Fe supply, in combination with the constitutive expression of AtFRO2, resulted in significantly higher concentrations of different minerals in roots (K, P, Zn, Ca, Ni, Mg and Mo, pod walls (Fe, K, P, Cu and Ni, leaves (Fe, P, Cu, Ca, Ni and Mg and seeds (Fe, Zn, Cu and Ni. Leaf and pod wall iron concentrations increased as much as 500% in transgenic plants, while seed iron concentrations only increased by 10%, suggesting that factors other than leaf and pod wall reductase activity were limiting the translocation of iron to seeds. Protoplasts isolated from transgenic leaves had three-fold higher reductase activity than controls. Expression levels of the iron storage protein, ferritin, were higher in the transgenic leaves than in wild-type, suggesting that the excess iron may be stored as ferritin in the leaves and therefore unavailable for phloem loading and delivery to the seeds. Also, citrate and malate levels in the roots and leaves of transgenic plants were significantly higher than in wild-type, suggesting that organic acid production could be related to the increased accumulation of minerals in roots, leaves and pod walls, but not in the seeds. All together, these results suggest a more ubiquitous role for the iron reductase in whole-plant mineral accumulation and

  8. Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion.

    Science.gov (United States)

    Shang, Lixia; Rockwell, Nathan C; Martin, Shelley S; Lagarias, J Clark

    2010-07-27

    Linear tetrapyrroles (bilins) perform important antioxidant and light-harvesting functions in cells from bacteria to humans. To explore the role of the propionate moieties in bilin metabolism, we report the semisynthesis of mono- and diamides of biliverdin IXalpha and those of its non-natural XIIIalpha isomer. Initially, these were examined as substrates of two types of NADPH-dependent biliverdin reductase, BVR and BvdR, and of the representative ferredoxin-dependent bilin reductase, phycocyanobilin:ferredoxin oxidoreductase (PcyA). Our studies indicate that the NADPH-dependent biliverdin reductases are less accommodating to amidation of the propionic acid side chains of biliverdin IXalpha than PcyA, which does not require free carboxylic acid side chains to yield its phytobilin product, phycocyanobilin. Bilin amides were also assembled with BV-type and phytobilin-type apophytochromes, demonstrating a role for the 8-propionate in the formation of the spectroscopically native P(r) dark states of these biliprotein photosensors. Neither ionizable propionate side chain proved to be essential to primary photoisomerization for both classes of phytochromes, but an unsubstituted 12-propionate was required for full photointerconversion of phytobilin-type phytochrome Cph1. Taken together, these studies provide insight into the roles of the ionizable propionate side chains in substrate discrimination by two bilin reductase families while further underscoring the mechanistic differences between the photoconversions of BV-type and phytobilin-type phytochromes.

  9. Biliverdin amides reveal roles for propionate side chains in bilin reductase recognition and in holophytochrome assembly and photoconversion†

    Science.gov (United States)

    Shang, Lixia; Rockwell, Nathan C.; Martin, Shelley S.; Lagarias, J. Clark

    2010-01-01

    Linear tetrapyrroles (bilins) perform important antioxidant and light harvesting functions in cells from bacteria to humans. To explore the role of the propionate moieties in bilin metabolism, we report the semisynthesis of mono- and di-amides of biliverdin IXα and those of its non-natural XIIIα isomer. Initially, these were examined as substrates of two types of NADPH-dependent biliverdin reductase, BVR and BvdR, and of the representative ferredoxin-dependent bilin reductase, phycocyanobilin:ferredoxin oxidoreductase (PcyA). Our studies indicate that the NADPH-dependent biliverdin reductases are less accommodating to amidation of the propionic acid sidechains of biliverdin IXα than PcyA, which does not require free carboxylic acid sidechains to yield its phytobilin product, phycocyanobilin. Bilin amides were also assembled with BV-type and phytobilin-type apophytochromes, demonstrating a role for the 8-propionate in formation of the spectroscopically native Pr dark states of these biliprotein photosensors. Neither ionizable propionate sidechain proved essential to primary photoisomerization for both classes of phytochromes, but an unsubstituted 12-propionate was required for full photointerconversion of phytobilin-type phytochrome Cph1. Taken together, these studies provide insight into the roles of the ionizable propionate sidechains in substrate discrimination by two bilin reductase families while further underscoring the mechanistic differences between the photoconversions of BV-type and phytobilin-type phytochromes. PMID:20565135

  10. 5 alpha-reductase inhibition by a new synthetic steroid (PM-9) in cultures of Penicillium crustosum.

    Science.gov (United States)

    Cabeza, Marisa; Quiroz, Alexandra; Bratoeff, Eugene; García, Genoveva; Ramírez, Elena; Flores, Eugenio

    2002-01-01

    The conversion of testosterone (T) to 5 alpha-dihydrotestosterone (DHT), plus the presence of 5 alpha-reductase enzyme, which is responsible for this reduction, had been demonstrated in P. crustosum broth. This enzyme is also present in androgen-dependent animal and human tissues such as prostate and seminal vesicles. The increase in the conversion of T to DHT has been implicated in androgen-dependent diseases such as benign prostate hyperplasia and prostate cancer. The use of 5 alpha-reductase inhibitors could mitigate these illnesses by inhibiting the DHT-receptor complex formation. The purpose of this study is to determine the inhibition pattern of 5 alpha-reductase by finasteride and PM-9 in P. crustosum broth. Km and Vmax values were determined in the broth by Lineweaver-Burk plots using different testosterone concentrations. The Km value was 0.22 microM and Vmax 0.833 pmol of DHT/mg of mycelium/day. The inhibition pattern of finasteride and PM-9 was also determined by Lineweaver-Burk plot, using different concentrations of T and inhibitors. The results of this study show that both finasteride and PM-9 inhibit 5 alpha-reductase in a competitive manner.

  11. Synthesis of the [beta]-D-glucosyl ester of [carbonyl-[sup 13]C]-indole-3-acetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Jakas, A.; Magnus, V. (Rudjer Boskovic Inst., Zagreb (Croatia)); Horvat, S.; Sandberg, G. (Swedish Univ. of Agricultural Sciences, Uppsala (Sweden))

    1993-10-01

    An efficient, operationally simple synthetic approach to 1-O-([carbonyl-[sup 13]C]-indole-3'-ylacetyl)-[beta]-D-glucopyranose is described. The synthesis was carried out by fusing a fully benzylated 1-O-glucosylpseudourea intermediate with [carbonyl-[sup 13]C]-indole-3-acetic acid, followed by hydrogenolytic removal of the protective groups. (Author).

  12. In situ visualization of carbonylation and its co-localization with proteins, lipids, DNA and RNA in Caenorhabditis elegans.

    Science.gov (United States)

    Kuzmic, Mira; Javot, Hélène; Bonzom, Jean-Marc; Lecomte-Pradines, Catherine; Radman, Miroslav; Garnier-Laplace, Jacqueline; Frelon, Sandrine

    2016-12-01

    All key biological macromolecules are susceptible to carbonylation - an irreparable oxidative damage with deleterious biological consequences. Carbonyls in proteins, lipids and DNA from cell extracts have been used as a biomarker of oxidative stress and aging, but formation of insoluble aggregates by carbonylated proteins precludes quantification. Since carbonylated proteins correlate with and become a suspected cause of morbidity and mortality in some organisms, there is a need for their accurate quantification and localization. Using appropriate fluorescent probes, we have developed an in situ detection of total proteins, DNA, RNA, lipids and carbonyl groups at the level of the whole organism. In C. elegans, we found that after UV irradiation carbonylation co-localizes mainly with proteins and, to a lesser degree, with DNA, RNA and lipids. The method efficiency was illustrated by carbonylation induction assessment over 5 different UV doses. The procedure enables the monitoring of carbonylation in the nematode C. elegans during stress, aging and disease along its life cycle including the egg stage. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Shotgun redox proteomics: identification and quantitation of carbonylated proteins in the UVB-resistant marine bacterium, Photobacterium angustum S14.

    Directory of Open Access Journals (Sweden)

    Sabine Matallana-Surget

    Full Text Available UVB oxidizes proteins through the generation of reactive oxygen species. One consequence of UVB irradiation is carbonylation, the irreversible formation of a carbonyl group on proline, lysine, arginine or threonine residues. In this study, redox proteomics was performed to identify carbonylated proteins in the UVB resistant marine bacterium Photobacterium angustum. Mass-spectrometry was performed with either biotin-labeled or dinitrophenylhydrazide (DNPH derivatized proteins. The DNPH redox proteomics method enabled the identification of 62 carbonylated proteins (5% of 1221 identified proteins in cells exposed to UVB or darkness. Eleven carbonylated proteins were quantified and the UVB/dark abundance ratio was determined at both the protein and peptide levels. As a result we determined which functional classes of proteins were carbonylated, which residues were preferentially modified, and what the implications of the carbonylation were for protein function. As the first large scale, shotgun redox proteomics analysis examining carbonylation to be performed on bacteria, our study provides a new level of understanding about the effects of UVB on cellular proteins, and provides a methodology for advancing studies in other biological systems.

  14. Shotgun redox proteomics: identification and quantitation of carbonylated proteins in the UVB-resistant marine bacterium, Photobacterium angustum S14.

    Science.gov (United States)

    Matallana-Surget, Sabine; Cavicchioli, Ricardo; Fauconnier, Charles; Wattiez, Ruddy; Leroy, Baptiste; Joux, Fabien; Raftery, Mark J; Lebaron, Philippe

    2013-01-01

    UVB oxidizes proteins through the generation of reactive oxygen species. One consequence of UVB irradiation is carbonylation, the irreversible formation of a carbonyl group on proline, lysine, arginine or threonine residues. In this study, redox proteomics was performed to identify carbonylated proteins in the UVB resistant marine bacterium Photobacterium angustum. Mass-spectrometry was performed with either biotin-labeled or dinitrophenylhydrazide (DNPH) derivatized proteins. The DNPH redox proteomics method enabled the identification of 62 carbonylated proteins (5% of 1221 identified proteins) in cells exposed to UVB or darkness. Eleven carbonylated proteins were quantified and the UVB/dark abundance ratio was determined at both the protein and peptide levels. As a result we determined which functional classes of proteins were carbonylated, which residues were preferentially modified, and what the implications of the carbonylation were for protein function. As the first large scale, shotgun redox proteomics analysis examining carbonylation to be performed on bacteria, our study provides a new level of understanding about the effects of UVB on cellular proteins, and provides a methodology for advancing studies in other biological systems.

  15. Seasonal, diurnal and nocturnal variations of carbonyl compounds in the semi-urban environment of Orléans, France.

    Science.gov (United States)

    Jiang, Zhaohui; Grosselin, Benoît; Daële, Véronique; Mellouki, Abdelwahid; Mu, Yujing

    2016-02-01

    Atmospheric carbonyls were measured at a semi-urban site in Orléans, France, from October 2010 to July 2011. Formaldehyde, acetaldehyde and acetone were found to be the most abundant carbonyls, with average concentrations of 3.1, 1.0, 2.0 ppb, respectively in summer, 2.3, 0.7, 2.2 ppb, respectively in autumn, 2.2, 1.0, 2.1 ppb, respectively in spring, and 1.5, 0.7, 1.1 ppb, respectively in winter. Photo-oxidation of volatile organic compounds (VOCs) was found to make a remarkable contribution to atmospheric carbonyls in the semi-urban site based on the distinct seasonal and diurnal variations of the carbonyls, as well as the significantly positive correlations between the carbonyls and ozone. The significantly negative correlations between NOx and O3 as well as the carbonyls and the positive correlations between wind speed and O3 as well as the carbonyls implied that the carbonyls and O3 at the semi-urban site were probably formed during air mass transport from neighboring cities. Copyright © 2015. Published by Elsevier B.V.

  16. Isolation and characterization of cDNAs encoding leucoanthocyanidin reductase and anthocyanidin reductase from Populus trichocarpa.

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    Full Text Available Proanthocyanidins (PAs contribute to poplar defense mechanisms against biotic and abiotic stresses. Transcripts of PA biosynthetic genes accumulated rapidly in response to infection by the fungus Marssonina brunnea f.sp. multigermtubi, treatments of salicylic acid (SA and wounding, resulting in PA accumulation in poplar leaves. Anthocyanidin reductase (ANR and leucoanthocyanidin reductase (LAR are two key enzymes of the PA biosynthesis that produce the main subunits: (+-catechin and (--epicatechin required for formation of PA polymers. In Populus, ANR and LAR are encoded by at least two and three highly related genes, respectively. In this study, we isolated and functionally characterized genes PtrANR1 and PtrLAR1 from P. trichocarpa. Phylogenetic analysis shows that Populus ANR1 and LAR1 occurr in two distinct phylogenetic lineages, but both genes have little difference in their tissue distribution, preferentially expressed in roots. Overexpression of PtrANR1 in poplar resulted in a significant increase in PA levels but no impact on catechin levels. Antisense down-regulation of PtrANR1 showed reduced PA accumulation in transgenic lines, but increased levels of anthocyanin content. Ectopic expression of PtrLAR1 in poplar positively regulated the biosynthesis of PAs, whereas the accumulation of anthocyanin and flavonol was significantly reduced (P<0.05 in all transgenic plants compared to the control plants. These results suggest that both PtrANR1 and PtrLAR1 contribute to PA biosynthesis in Populus.

  17. The role of light in the inducation of nitrate reductase and nitrite reductase in cucumber seedlings

    Directory of Open Access Journals (Sweden)

    J. Buczek

    2015-01-01

    Full Text Available The activity of nitrate reductase (NR and nitrite reductase (NiR was investigated in vivo and in vitro in the roots and NR activity in 3-day-old cotyledons of cucumber seedlings. NR activity in the roots appears almost immediately after addition of nitrate ions to the induction medium, whereas, in the cotyledones NR induction is delayed. In general light enhances NR activity in the cotyledons and depresses it in the roots in experiments of short duration. Etiolation of the cotyledons reduces NR activity in the roots and leads to disappearance of the activity of this enzyme in the cotyledons, whereas the NR activity of roots kept in darkness, after transfer of the etiolated plants to light, increases threefold. In roots growing in darkness a delay in NiR induction is observed, while in those growing in ligth it occurs at the same time as NR induction. Chlormaphenicol (CAP, cycloheximide (CHI and actinomycin D (ACM applied at the beginning of the period of seedling induction with initrates inhibit NR activity in the cotyledons, whereas in the roots only CHI and ACM exert such an effect. To sum up, NR is synthesized in cucumber roots and cotyledons de novo on the cytoplasmic polyribosomes, and light per se is not indispensable for this synthesis, but it has an indirect influence on the activity level of NR and NiR both in the roots and the cotyledons.

  18. Purification and Properties of an NADPH-Aldose Reductase (Aldehyde Reductase) from Euonymus japonica Leaves

    Science.gov (United States)

    Negm, Fayek B.

    1986-01-01

    The enzyme aldose (aldehyde) reductase was partially purified (142-fold) and characterized from Euonymus japonica leaves. The reductase, a dimer, had an average molecular weight of 67,000 as determined by gel filtration on Sephadex G-100. The enzyme was NADPH specific and reduced a broad range of substrates including aldoses, aliphatic aldehydes, and aromatic aldehydes. Maximum activity was observed at pH 8 in phosphate and Tris-HCl buffers and at pH 8.6 to 9.0 in glycine-NaOH buffer using dl-glyceraldehyde or 3-pyridinecarboxaldehyde as substrate. NADP was a competitive inhibitor with respect to NADPH with a Ki of 60 micromolar. Glycerol was an uncompetitive inhibitor to dl-glyceraldehyde (K′i = 460 millimolar). The Euonymus enzyme was inhibited by sulfhydryl inhibitor, phenobarbital, and high concentrations of Li2SO4. Pyrazol and metal chelating agents inhibited the enzyme slightly. Enzyme activity was detected in the leaves and berries of Celastrus orbiculatus and several species of Euonymus. Probable function of this enzyme is to reduce d-galactose to galactitol, a characteristic metabolite in phloem sap of members of the Celastraceae family. Images Fig. 1 PMID:16664750

  19. Modular Approach for Novel Nanostructered Polycondensates Enabled by the Unique Selectivity of Carbonyl Biscaprolactam

    NARCIS (Netherlands)

    Loontjens, Ton

    2003-01-01

    New enabling chemistries have been developed to produce novel well-defined polymeric materials through the additions of small amounts of reactive functional compounds to standard polymers during regular processing steps. We found that carbonyl biscaprolactam and its derivatives couple polymer chains

  20. Efficient and selective α-bromination of carbonyl compounds with N-bromosuccinimide under microwave

    Directory of Open Access Journals (Sweden)

    Xiao-Yu Guan

    2015-11-01

    Full Text Available A highly efficient method for the synthesis of α-halocarbonyl compounds has been achieved via selective monobromination of aromatic and aliphatic carbonyl compounds with N-bromosuccinimide catalyzed by p-toluenesulfonic acid under microwave irradiation within 30 min.

  1. One-pot Reductive Amination of Carbonyl Compounds with NaBH₄ ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 129; Issue 1. One-pot Reductive Amination of Carbonyl Compounds with NaBH₄-B(OSO₃H)₃/SiO₂ in Acetonitrile and in Solvent-free Condition. HOSEIN HAMADI SAMIRA JAVADI. Regular Article Volume 129 Issue 1 January 2017 pp 75-80 ...

  2. Enantioselective α-Arylation of Carbonyls via Cu(I)-Bisoxazoline Catalysis

    Science.gov (United States)

    Harvey, James S.; Simonovich, Scott P.; Jamison, Christopher R.; MacMillan, David W. C.

    2011-01-01

    The enantioselective α-arylation of both lactones and acyl oxazolidones has been accomplished using a combination of diaryliodonium salts and copper catalysis. These mild catalytic conditions provide a new strategy for the enantioselective construction and retention of enolizable α-carbonyl benzylic stereocenters, a valuable synthon for the production of medicinal agents. PMID:21848265

  3. Direct photolysis of carbonyl compounds dissolved in cloud and fog~droplets

    Science.gov (United States)

    Epstein, S. A.; Tapavicza, E.; Furche, F.; Nizkorodov, S. A.

    2013-09-01

    Gas-phase photolysis is an important tropospheric sink for many carbonyl compounds; however the significance of direct photolysis of these compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived effective Henry's law constants, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will (or will not) have competitive aqueous photolysis rates. We also present molecular dynamics simulations designed to estimate gas- and aqueous-phase extinction coefficients of unstudied atmospherically relevant compounds found in d-limonene and isoprene secondary organic aerosol. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water-soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only two out of the 92 carbonyl compounds investigated, pyruvic acid and acetoacetic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α,β-conjugation that were investigated, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected under typical atmospheric conditions.

  4. Direct photolysis of carbonyl compounds dissolved in cloud and fog~droplets

    Directory of Open Access Journals (Sweden)

    S. A. Epstein

    2013-09-01

    Full Text Available Gas-phase photolysis is an important tropospheric sink for many carbonyl compounds; however the significance of direct photolysis of these compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived effective Henry's law constants, hydration equilibrium parameters, aqueous hydroxyl radical (OH rate constants, and optical extinction coefficients to identify types of compounds that will (or will not have competitive aqueous photolysis rates. We also present molecular dynamics simulations designed to estimate gas- and aqueous-phase extinction coefficients of unstudied atmospherically relevant compounds found in d-limonene and isoprene secondary organic aerosol. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water-soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only two out of the 92 carbonyl compounds investigated, pyruvic acid and acetoacetic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α,β-conjugation that were investigated, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected under typical atmospheric conditions.

  5. Ketene as a Reaction Intermediate in the Carbonylation of Dimethyl Ether to Methyl Acetate over Mordenite

    DEFF Research Database (Denmark)

    Rasmussen, Dominik Bjørn; Christensen, Jakob Munkholt; Temel, Burcin

    2015-01-01

    Unprecedented insight into the carbonylation of dimethyl ether over Mordenite is provided through the identification of ketene (CH2CO) as a reaction intermediate. The formation of ketene is predicted by detailed DFT calculations and verified experimentally by the observation of doubly deuterated ...

  6. [pi] Backbonding in Carbonyl Complexes and Carbon-Oxygen Stretching Frequencies: A Molecular Modeling Exercise

    Science.gov (United States)

    Montgomery, Craig D.

    2007-01-01

    An exercise is described that has illustrated the effect of various factors on [pi] backbonding to carbonyl ligands, where the students can view the molecular orbitals corresponding to the M-CO [pi] interaction as well as the competing interaction between the metal and co-ligands. The visual and hands-on nature of the modeling exercise has helped…

  7. Infrared Spectroscopy and Structures of Cobalt Carbonyl Cations, Co(CO)(n)(+) (n=1-9)

    NARCIS (Netherlands)

    Ricks, A. M.; Bakker, J. M.; Douberly, G. E.; Duncan, M. A.

    2009-01-01

    Cobalt carbonyl cations of the form Co(CO)(n)(+) (n = 1-9) are produced in a molecular beam by laser vaporization in a pulsed nozzle source. These ions, and their corresponding "argon-tagged" analogues, Co(CO)(n)(Ar)(m)(+), are studied with mass-selected infrared photodissociation

  8. Additive role of attapulgite nanoclay on carbonyl iron-based magnetorheological suspension

    CSIR Research Space (South Africa)

    Chae, HS

    2014-09-01

    Full Text Available Attapulgite (ATP), a fibrous nanoclay mineral, was adopted as an additive in this study to improve the sedimentation problem of soft magnetic carbonyl iron (CI)-based magnetorheological (MR) fluids caused by the density mismatch between the CI...

  9. Canopy uptake dominates nighttime carbonyl sulfide fluxes in a boreal forest

    NARCIS (Netherlands)

    Kooijmans, Linda MJ; Maseyk, Kadmiel; Seibt, Ulli; Sun, Wu; Vesala, Timo; Mammarella, Ivan; Kolari, Pasi; Aalto, Juho; Franchin, Alessandro; Vecchi, Roberta; Valli, Gianluigi; Chen, Huilin

    2017-01-01

    Nighttime vegetative uptake of carbonyl sulfide (COS) can exist due to the incomplete closure of stomata and the light independence of the enzyme carbonic anhydrase, which complicates the use of COS as a tracer for gross primary productivity (GPP). In this study we derived night-time COS fluxes in a

  10. Oxalyl chloride as a practical carbon monoxide source for carbonylation reactions

    DEFF Research Database (Denmark)

    Hansen, Steffen V F; Ulven, Trond

    2015-01-01

    A method for generation of high-quality carbon monoxide by decomposition of oxalyl chloride in an aqueous hydroxide solution is described. The usefulness of the method is demonstrated in the synthesis of heterocycles and for hydroxy-, alkoxy-, amino-, and reductive carbonylation reactions...

  11. Palladium-catalyzed carbonylative sonogashira coupling of aryl bromides using near stoichiometric carbon monoxide

    DEFF Research Database (Denmark)

    Neumann, Karoline T.; Laursen, Simon R.; Lindhardt, Anders T.

    2014-01-01

    A general procedure for the palladium-catalyzed carbonylative Sonogashira coupling of aryl bromides is reported, using near stoichiometric amounts of carbon monoxide. The method allows a broad substrate scope in moderate to excellent yields. The formed alkynone motive serves as a platform...

  12. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

    Science.gov (United States)

    One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

  13. Contribution of carbonyl photochemistry to aging of atmospheric secondary organic aerosol.

    Science.gov (United States)

    Mang, Stephen A; Henricksen, Dana K; Bateman, Adam P; Andersen, Mads P Sulbaek; Blake, Donald R; Nizkorodov, Sergey A

    2008-09-11

    The photodegradation of secondary organic aerosol (SOA) material by actinic UV radiation was investigated. SOA was generated via the dark reaction of ozone and d-limonene, collected onto quartz-fiber filters, and exposed to wavelength-tunable radiation. Photochemical production of CO was monitored in situ by infrared cavity ring-down spectroscopy. A number of additional gas-phase products of SOA photodegradation were observed by gas chromatography, including methane, ethene, acetaldehyde, acetone, methanol, and 1-butene. The absorption spectrum of SOA material collected onto CaF2 windows was measured and compared with the photolysis action spectrum for the release of CO, a marker for Norrish type-I photocleavage of carbonyls. Both spectra had a band at approximately 300 nm corresponding to the overlapping n --> pi* transitions in nonconjugated carbonyls. The effective extinction coefficient of freshly prepared SOA was estimated to be on the order of 15 L mol(-1) cm(-1) at 300 nm, implying one carbonyl group in every SOA constituent. The absorption by the SOA material slowly increased in the visible and near-UV during storage of SOA in open air in the dark, presumably as a result of condensation reactions that increased the degree of conjugation in the SOA constituents. These observations suggest that photolysis of carbonyl functional groups represents a significant sink for monoterpene SOA compounds in the troposphere, with an estimated lifetime of several hours over the continental United States.

  14. Iron Dextran treatment does not induce serum protein carbonyls in the newborn pig

    Science.gov (United States)

    Oxidation of serum proteins can lead to carbonyl formation which alters their function and is often associated with stress-related diseases. Since it is recommended that all pigs reared in modern production facilities be given supplemental iron at birth to prevent anemia, and metals can catalyze th...

  15. Proteomic and carbonylation profile analysis of rat skeletal muscles following acute swimming exercise.

    Directory of Open Access Journals (Sweden)

    Francesca Magherini

    Full Text Available Previous studies by us and other groups characterized protein expression variation following long-term moderate training, whereas the effects of single bursts of exercise are less known. Making use of a proteomic approach, we investigated the effects of acute swimming exercise (ASE on protein expression and carbonylation patterns in two hind limb muscles: the Extensor Digitorum Longus (EDL and the Soleus, mostly composed of fast-twitch and slow-twitch fibres, respectively. Carbonylation is one of the most common oxidative modifications of proteins and a marker of oxidative stress. In fact, several studies suggest that physical activity and the consequent increase in oxygen consumption can lead to increase in reactive oxygen and nitrogen species (RONS production, hence the interest in examining the impact of RONS on skeletal muscle proteins following ASE. Results indicate that protein expression is unaffected by ASE in both muscle types. Unexpectedly, the protein carbonylation level was reduced following ASE. In particular, the analysis found 31 and 5 spots, in Soleus and EDL muscles respectively, whose carbonylation is reduced after ASE. Lipid peroxidation levels in Soleus were markedly reduced as well. Most of the decarbonylated proteins are involved either in the regulation of muscle contractions or in the regulation of energy metabolism. A number of hypotheses may be advanced to account for such results, which will be addressed in future studies.

  16. Enantioselective gamma- and delta-Borylation of Unsaturated Carbonyl Derivatives: Synthesis, Mechanistic Insights, and Applications

    Science.gov (United States)

    Hoang, Gia L.

    Chiral boronic esters are valuable synthetic intermediates widely used in a variety of stereospecific transformations. Transition metal-catalyzed asymmetric hydroboration (CAHB) of alkenes is among the most popular methods for their preparation. Enantioselective hydroboration of activated alkenes (i.e., vinyl arene derivatives or conjugated carbonyl compounds) have been extensively studied by many research groups. We, on the other hand, are interested in enantioselective hydroboration of unactivated alkenes utilizing coordinating functional groups (e.g., carbonyl derivatives) to give functionalized, chiral boronic esters. While conjugate addition and C-H activation methodologies provide efficient alternatives to CAHB for enantioselective beta-borylation of carbonyl compounds, direct gamma- and delta-borylations were essentially unknown prior to our wok on CAHB. The gamma-borylated products were used for understanding stereochemical aspects of Suzuki-Miyaura cross-coupling reactions resulting in stereoretention and in contrast to similar beta-borylated carbonyl derivatives reported in literature. Some other selected transformations were carried out to construct a number of biologically relevant structural motifs, such as lignan precursors, 1,4-amino alcohols, gamma-amino acid derivatives, 5-substitued-gamma-lactone and lactam ring systems. In addition, collaborative experimental and computational studies of the enantioselective desymmetrization via CAHB gain a better understanding of the mechanistic pathways.

  17. NMR Studies of Structure-Reactivity Relationships in Carbonyl Reduction: A Collaborative Advanced Laboratory Experiment

    Science.gov (United States)

    Marincean, Simona; Smith, Sheila R.; Fritz, Michael; Lee, Byung Joo; Rizk, Zeinab

    2012-01-01

    An upper-division laboratory project has been developed as a collaborative investigation of a reaction routinely taught in organic chemistry courses: the reduction of carbonyl compounds by borohydride reagents. Determination of several trends regarding structure-activity relationship was possible because each student contributed his or her results…

  18. Cobalt-catalysed C-H carbonylative cyclisation of aliphatic amides.

    Science.gov (United States)

    Williamson, Patrick; Galván, Alicia; Gaunt, Matthew J

    2017-04-01

    A cobalt-catalysed C-H carbonylation of aliphatic carboxamide derivatives is described, employing commercially available Co(ii)-salts in the presence of a silver oxidant. This operationally simple process utilises an atmospheric pressure of CO and generates a range of substituted succinimide products bearing diverse functional groups that can be successfully accessed via this methodology.

  19. Levels, sources and health risks of carbonyls and BTEX in the ambient air of Beijing, China.

    Science.gov (United States)

    Zhang, Yujie; Mu, Yujing; Liu, Junfeng; Mellouki, Abdelwahid

    2012-01-01

    The atmospheric concentrations of carbonyls and BTEX (benzene, toluene, ethylbenzene, m,p-xylene and o-xylene) were measured simultaneously at a same sampling site in Beijing from September 2008 to August 2010. The average concentrations of the total measured carbonyls during autumn, winter, spring, and summer were 37.7, 31.3, 39.7, 50.5 microg/m3, respectively, and maximal values for their diurnal variations usually happened at noontime. In contrast to carbonyls, the average concentrations of the total measured BTEX during the four seasons were 27.2, 31.9, 23.2, 19.1 microg/m3, respectively, and minimal values for their diurnal variations always occurred in the early afternoon. The average concentration for carbonyls increased about 24% from September 2008-August 2009 to September 2009-August 2010, for BTEX, increased about 15%. Integrated life time cancer risks for three carcinogens (benzene, formaldehyde and acetaldehyde) in Beijing exceeded the value of 1E-06, and the hazard quotient (HQ) of non-cancer risk of exposure to formaldehyde exceeded unity.

  20. Cell signaling promoting protein carbonylation does not cause sulfhydryl oxidation: Implications to the mechanism of redox signaling [version 1; referees: 1 approved, 2 approved with reservations

    Directory of Open Access Journals (Sweden)

    Yuichiro J. Suzuki

    2017-04-01

    Full Text Available Reactive oxygen species (ROS have been recognized as second messengers, however, targeting mechanisms for ROS in cell signaling have not been defined. While ROS oxidizing protein cysteine thiols has been the most popular proposed mechanism, our laboratory proposed that ligand/receptor-mediated cell signaling involves protein carbonylation. Peroxiredoxin-6 (Prx6 is one protein that is carbonylated at 10 min after the platelet-derived growth factor (PDGF stimulation of human pulmonary artery smooth muscle cells. In the present study, the SulfoBiotics Protein Redox State Monitoring Kit Plus (Dojindo Molecular Technologies was used to test if cysteine residues of Prx6 are oxidized in response to the PDGF stimulation. Human Prx6 has a molecular weight of 25 kDa and contains two cysteine residues. The Dojindo system adds the 15 kDa Protein-SHifter if these cysteine residues are reduced in the cells. Results showed that, in untreated cells, the Prx6 molecule predominantly exhibited the 55 kDa band, indicating that both cysteine residues are reduced in the cells. Treatment of cells with 1 mM H2O2 caused the disappearance of the 55 kDa band and the appearance of a 40 kDa band, suggesting that the high concentration of H2O2 oxidized one of the two cysteine residues in the Prx6 molecule. By contrast, PDGF stimulation had no effects on the thiol status of the Prx6 molecule. We concluded that protein carbonylation is a more sensitive target of ROS during ligand/receptor-mediated cell signaling than sulfhydryl oxidation.

  1. Pancreaticobiliary cancers with deficient methylenetetrahydrofolate reductase genotypes.

    Science.gov (United States)

    Matsubayashi, Hiroyuki; Skinner, Halcyon G; Iacobuzio-Donahue, Christine; Abe, Tadayoshi; Sato, Norihiro; Riall, Taylor Sohn; Yeo, Charles J; Kern, Scott E; Goggins, Michael

    2005-08-01

    Methyl group deficiency might promote carcinogenesis by inducing DNA breaks and DNA hypomethylation. We hypothesized that deficient methylenetetrahydrofolate reductase (MTHFR) genotypes could promote pancreatic cancer development. First, we performed a case-control study of germline MTHFR polymorphisms (C677T, A1298C) in 303 patients with pancreatic cancer and 305 matched control subjects. Pancreatic neoplasms frequently lose an MTHFR allele during tumorigenesis; we hypothesized that such loss could promote carcinogenesis. We therefore evaluated the cancer MTHFR genotypes of 82 patients with pancreaticobiliary cancers and correlated them to genome-wide measures of chromosomal deletion by using 386 microsatellite markers. Finally, MTHFR genotypes were correlated with global DNA methylation in 68 cancer cell lines. Germline MTHFR polymorphisms were not associated with an increased likelihood of having pancreatic cancer. Fractional allelic loss (a measure of chromosomal loss) trended higher in cancers with 677T genotypes than in cancers with other genotypes (P = .055). Among cancers with loss of an MTHFR allele, cancers with 677T MTHFR alleles had more deletions at folate-sensitive fragile sites (36.9%) and at tumor suppressor gene loci (68.5%) than 677C cancers (28.7% and 47.8%, P = .079 and .014, respectively). LINE1 methylation was lower in cancers with less functional 677T/TT genotypes (24.4%) than in those with 677CT (26.0%) and CC/C genotypes (32.5%) (P = .014). Cancers with defective MTHFR genotypes have more DNA hypomethylation and more chromosomal losses. Deficient MTHFR function due to loss of an MTHFR allele by an evolving neoplasm might, by promoting chromosomal losses, accelerate cancer development.

  2. Preparation and characterization of carbonyl iron/poly(butylcyanoacrylate) core/shell nanoparticles.

    Science.gov (United States)

    Arias, J L; Gallardo, V; Linares-Molinero, F; Delgado, A V

    2006-07-15

    In this article a method is described to prepare composite colloidal nanoparticles, consisting of a magnetic core (carbonyl iron) and a biodegradable polymeric shell [poly(butylcyanoacrylate) or PBCA]. The method is based on the so-called anionic polymerization procedure, often used in the synthesis of poly(alkylcyanoacrylate) nanospheres designed for drug delivery. Interest of this investigation is based upon the fact that the heterogeneous structure of the particles can confer them both the possibility to respond to external magnetic fields and to be used as drug carriers. In order to investigate to what extent do the particles participate of this mixed properties, we compare in this work the physical characteristics (structure, chemical composition, specific surface area and surface electrical and thermodynamic properties) of the core/shell particles with those of both the nucleus and the coating material. This preliminary study shows that the mixed particles display an intermediate behavior between that of carbonyl iron and PBCA spheres. Electrophoretic mobility measurements as a function of pH and as a function of KNO3 concentration, show a great similarity between the core/shell and pure polymer nanoparticles. Similarly, a surface thermodynamic study performed on the three types of particles demonstrated that the electron-donor component of the surface free energy of the solids is very sensitive to the surface composition. In fact, a measurable decrease of such component is found for core/shell particles as compared to carbonyl iron. We also analyzed the influence of the relative amounts of polymer and carbonyl iron on the characteristics of the composite particles: data on the coating thickness, the amount of polymer bound to the magnetic nuclei, the redispersibility characteristics of the suspensions and the surface electrical and thermodynamic properties, suggest that the optimal synthesis conditions are obtained for a 4/3 initial monomer/carbonyl iron

  3. Gas-phase chemistry of Mo, Ru, W, and Os metal carbonyl complexes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Qin, Z.; Fan, F.L. [Chinese Academy of Sciences, Lanzhou (China). Inst. of Modern Physics; and others

    2014-04-01

    Metal carbonyl complexes were used for studying the gas-phase chemical behavior of Mo, Ru, W and Os isotopes with an on-line low temperature isothermal gas chromatography apparatus. Short-lived Mo and Ru isotopes were produced by a {sup 252}Cf spontaneous fission source. Short-lived nuclides of W and Os were produced using the heavy ion reactions {sup 19}F + {sup 159}Tb and {sup 165}Ho, respectively. Short-lived products were thermalized in a recoil chamber filled with a gas mixture of helium and carbon monoxide. The carbonyls formed were then transported through capillaries to an isothermal chromatography column for study of the adsorption behavior as a function of temperature. On-line isothermal chromatography (IC) experiments on Teflon (PTFE) and quartz surfaces showed that short-lived isotopes of the listed elements can form carbonyl complexes which are very volatile and interact most likely in physical sorption processes. Deduced adsorption enthalpies of Mo and Ru carbonyls were -38 ± 2 kJ/mol and -36 ± 2 kJ/mol, respectively. These values are in good agreement with literature data, partly obtained with different chromatographic techniques. A validation of the applied Monte Carlo model to deduce adsorption enthalpies with Mo isotopes of different half-lives proved the validity of the underlying adsorption model. The investigations using a gas-jet system coupled to a heavy ion accelerator without any preseparator clearly showed the limitations of the approach. The He and CO gas mixture, which was directly added into the chamber, will result in decomposition of CO gas and produce some aerosol particles. After the experiment of {sup 173}W and {sup 179}Os in the heavy ion experiments, the Teflon column was covered by a yellowish deposit; the adsorption enthalpy of W and Os carbonyls could therefore not be properly deduced using Monte Carlo simulations. (orig.)

  4. Spatial distributions of airborne di-carbonyls in urban and rural areas in China

    Science.gov (United States)

    Lui, K. H.; Dai, Wen-Ting; Chan, C. S.; Ho, Steven Sai Hang; Cao, Jun-Ji; Lee, S. C.; Ho, K. F.

    2017-04-01

    Gaseous glyoxal and methylglyoxal concentrations were characterized in nine cities of China during 2010-2011. The average summer (winter) glyoxal and methylglyoxal concentrations were 36.4-178.4 (12.3-241.4) and 67.8-359.4 (28.4-530.0) ng/m3, respectively. In summer, the highest average glyoxal concentration was in Guangzhou (GZ), while the lowest was in Shanghai (SH). In winter, Xiamen (XM) showed the highest average methylglyoxal concentration and Yantai (YT) reported the lowest. Both di-carbonyls showed distinct seasonal variations. The maximum average methylglyoxal concentration was approximately twice as much as glyoxal, which is consistent with the results of other studies. Glyoxal-to-methylglyoxal ratios showed that there was a consistent direct source of emissions in remote areas such as Qinghai Lake and Lhasa in both seasons (r ≥ 0.9). Pearson's correlation analysis suggested possible similar sources formation (R ≥ 0.7) for the two di-carbonyls in winter. Multiple linear regression analyses demonstrated that every 1 °C temperature increase could lead to a > 2% increase in the concentration of the di-carbonyls in both seasons. There was a greater percentage gain for glyoxal in winter than in summer for the same temperature increase. The northeast monsoon occurs in winter, and for every 1 ms- 1 increase in wind speed, > 20% of the di-carbonyls can be transferred out of China. This study is useful to understand about the secondary organic aerosol formation in the areas, the statistical analysis can provide information about the relationships between these carbonyls in atmosphere.

  5. Susceptibility of the antioxidant selenoenyzmes thioredoxin reductase and glutathione peroxidase to alkylation-mediated inhibition by anticancer acylfulvenes

    OpenAIRE

    LIU, XIAODAN; Pietsch, Kathryn E.; Sturla, Shana J.

    2011-01-01

    Selenium, in the form of selenocysteine, is a critical component of some major redox-regulating enzymes, including thioredoxin reductase (TrxR) and glutathione peroxidase (Gpx). TrxR has emerged as an anticancer target for drug development due to its elevated expression level in many aggressive human tumors. Acylfulvenes (AFs) are semisynthetic derivatives of the natural product illudin S, and display improved cytotoxic selectivity profiles. AF and illudin S alkylate cellular macromolecules. ...

  6. Correlation of volatile carbonyl yields emitted by e-cigarettes with the temperature of the heating coil and the perceived sensorial quality of the generated vapours.

    Science.gov (United States)

    Geiss, Otmar; Bianchi, Ivana; Barrero-Moreno, Josefa

    2016-05-01

    E-liquids generally contain four main components: nicotine, flavours, water and carrier liquids. The carrier liquid dissolves flavours and nicotine and vaporises at a certain temperature on the atomizer of the e-cigarette. Propylene glycol and glycerol, the principal carriers used in e-liquids, undergo decomposition in contact with the atomizer heating-coil forming volatile carbonyls. Some of these, such as formaldehyde, acetaldehyde and acrolein, are of concern due to their adverse impact on human health when inhaled at sufficient concentrations. The aim of this study was to correlate the yield of volatile carbonyls emitted by e-cigarettes with the temperature of the heating coil. For this purpose, a popular commercial e-liquid was machine-vaped on a third generation e-cigarette which allowed the variation of the output wattage (5-25W) and therefore the heat generated on the atomizer heating-coil. The temperature of the heating-coil was determined by infrared thermography and the vapour generated at each temperature underwent subjective sensorial quality evaluation by an experienced vaper. A steep increase in the generated carbonyls was observed when applying a battery-output of at least 15W corresponding to 200-250°C on the heating coil. However, when considering concentrations in each inhaled puff, the short-term indoor air guideline value for formaldehyde was already exceeded at the lowest wattage of 5W, which is the wattage applied in most 2nd generation e-cigarettes. Concentrations of acetaldehyde in each puff were several times below the short-term irritation threshold value for humans. Acrolein was only detected from 20W upwards. The negative sensorial quality evaluation by the volunteering vaper of the vapour generated at 20W demonstrated the unlikelihood that such a wattage would be realistically set by a vaper. This study highlights the importance to develop standardised testing methods for the assessment of carbonyl-emissions and emissions of other

  7. Sulfite Reductase Activity in Extracts of Various Photosynthetic Bacteria

    Science.gov (United States)

    Peck, H. D.; Tedro, S.; Kamen, M. D.

    1974-01-01

    Extracts of representative bacterial strains from the various families of photosynthetic prokaryotes are demonstrated to possess significant levels of sulfite reductase [EC 1.8.99.1; hydrogen-sulfide: (acceptor)oxidoreductase] activity with reduced methyl viologen as electron donor, but not NADPH2. The enzyme is localized primarily in the soluble fraction of the extracts, in contrast to adenylysulfate reductase [EC 1.8.99.2; AMP, sulfite: (acceptor) oxidoreductase], which is bound normally in the membrane fractions of those bacteria in which it is found. Assignment of the sulfite reductase activities to the biosynthetic (“assimilatory”) pathway is suggested by levels of specific activity noted and ready solubility. PMID:4526215

  8. Intramolecular electron transfer in Pseudomonas aeruginosa cd(1) nitrite reductase

    DEFF Research Database (Denmark)

    Farver, Ole; Brunori, Maurizio; Cutruzzolà, Francesca

    2009-01-01

    The cd(1) nitrite reductases, which catalyze the reduction of nitrite to nitric oxide, are homodimers of 60 kDa subunits, each containing one heme-c and one heme-d(1). Heme-c is the electron entry site, whereas heme-d(1) constitutes the catalytic center. The 3D structure of Pseudomonas aeruginosa...... is controlling this internal ET step. In this study we have investigated the internal ET in the wild-type and His369Ala mutant of P. aeruginosa nitrite reductases and have observed similar cooperativity to that of the Pseudomonas stutzeri enzyme. Heme-c was initially reduced, in an essentially diffusion...... nitrite reductase has been determined in both fully oxidized and reduced states. Intramolecular electron transfer (ET), between c and d(1) hemes is an essential step in the catalytic cycle. In earlier studies of the Pseudomonas stutzeri enzyme, we observed that a marked negative cooperativity...

  9. Methemoglobin reductase activity in intact fish red blood cells

    DEFF Research Database (Denmark)

    Jensen, Frank B; Nielsen, Karsten

    2018-01-01

    Hb reductase activity in fish offsets their higher Hb autoxidation and higher likelihood of encountering elevated nitrite. Deoxygenation significantly raised the rates of RBC metHb reduction, and more so in rainbow trout than in carp. The temperature sensitivity of metHb reduction in rainbow trout RBCs......Red blood cells (RBCs) possess methemoglobin reductase activity that counters the ongoing oxidation of hemoglobin (Hb) to methemoglobin (metHb), which in circulating blood is caused by Hb autoxidation or reactions with nitrite. We describe an assay for determining metHb reductase activity in intact...... of counteracting oxidation. This assay was used to compare metHb reduction in rainbow trout and carp RBCs under both oxygenated and deoxygenated conditions. Washing resulted in effective wash-out of nitrite to low and safe values (~2μM). The subsequent decline in [metHb] with time followed first-order kinetics...

  10. Prokaryotic arsenate reductase enhances arsenate resistance in Mammalian cells.

    Science.gov (United States)

    Wu, Dan; Tao, Xuanyu; Wu, Gaofeng; Li, Xiangkai; Liu, Pu

    2014-01-01

    Arsenic is a well-known heavy metal toxicant in the environment. Bioremediation of heavy metals has been proposed as a low-cost and eco-friendly method. This article described some of recent patents on transgenic plants with enhanced heavy metal resistance. Further, to test whether genetic modification of mammalian cells could render higher arsenic resistance, a prokaryotic arsenic reductase gene arsC was transfected into human liver cancer cell HepG2. In the stably transfected cells, the expression level of arsC gene was determined by quantitative real-time PCR. Results showed that arsC was expressed in HepG2 cells and the expression was upregulated by 3 folds upon arsenate induction. To further test whether arsC has function in HepG2 cells, the viability of HepG2-pCI-ArsC cells exposed to arsenite or arsenate was compared to that of HepG2-pCI cells without arsC gene. The results indicated that arsC increased the viability of HepG2 cells by 25% in arsenate, but not in arsenite. And the test of reducing ability of stably transfected cells revealed that the concentration of accumulated trivalent arsenic increased by 25% in HepG2-pCI-ArsC cells. To determine the intracellular localization of ArsC, a fusion vector with fluorescent marker pEGFP-N1-ArsC was constructed and transfected into.HepG2. Laser confocal microscopy showed that EGFP-ArsC fusion protein was distributed throughout the cells. Taken together, these results demonstrated that prokaryotic arsenic resistant gene arsC integrated successfully into HepG2 genome and enhanced arsenate resistance of HepG2, which brought new insights of arsenic detoxification in mammalian cells.

  11. Sepiapterin Reductase Mediates Chemical Redox Cycling in Lung Epithelial Cells*

    Science.gov (United States)

    Yang, Shaojun; Jan, Yi-Hua; Gray, Joshua P.; Mishin, Vladimir; Heck, Diane E.; Laskin, Debra L.; Laskin, Jeffrey D.

    2013-01-01

    In the lung, chemical redox cycling generates highly toxic reactive oxygen species that can cause alveolar inflammation and damage to the epithelium, as well as fibrosis. In this study, we identified a cytosolic NADPH-dependent redox cycling activity in mouse lung epithelial cells as sepiapterin reductase (SPR), an enzyme important for the biosynthesis of tetrahydrobiopterin. Human SPR was cloned and characterized. In addition to reducing sepiapterin, SPR mediated chemical redox cycling of bipyridinium herbicides and various quinones; this activity was greatest for 1,2-naphthoquinone followed by 9,10-phenanthrenequinone, 1,4-naphthoquinone, menadione, and 2,3-dimethyl-1,4-naphthoquinone. Whereas redox cycling chemicals inhibited sepiapterin reduction, sepiapterin had no effect on redox cycling. Additionally, inhibitors such as dicoumarol, N-acetylserotonin, and indomethacin blocked sepiapterin reduction, with no effect on redox cycling. Non-redox cycling quinones, including benzoquinone and phenylquinone, were competitive inhibitors of sepiapterin reduction but noncompetitive redox cycling inhibitors. Site-directed mutagenesis of the SPR C-terminal substrate-binding site (D257H) completely inhibited sepiapterin reduction but had minimal effects on redox cycling. These data indicate that SPR-mediated reduction of sepiapterin and redox cycling occur by distinct mechanisms. The identification of SPR as a key enzyme mediating chemical redox cycling suggests that it may be important in generating cytotoxic reactive oxygen species in the lung. This activity, together with inhibition of sepiapterin reduction by redox-active chemicals and consequent deficiencies in tetrahydrobiopterin, may contribute to tissue injury. PMID:23640889

  12. Surface functionalization of carbonyl iron with aluminum phosphate coating toward enhanced anti-oxidative ability and microwave absorption properties

    Science.gov (United States)

    Duan, Wenju; Li, Xuandong; Wang, Ying; Qiang, Rong; Tian, Chunhua; Wang, Na; Han, Xijiang; Du, Yunchen

    2018-01-01

    Fe@AlPO4 core-shell composites with tunable AlPO4 content have been successfully prepared through in situ deposition of AlPO4 on the surface of carbonyl iron. The presence of the AlPO4 layer improves the anti-oxidative ability of the internal carbonyl iron, so that surface oxidation and magnetic degradation in these composites are significantly suppressed when compared with naked carbonyl iron. It is worth noting that the AlPO4 layer can affect the electromagnetic parameters of carbonyl iron, resulting in well-matched characteristic impedance. By optimizing the AlPO4 layer content, the Fe@AlPO4 composite can display excellent reflection loss characteristics, and qualified absorption in a very broad frequency range (2.4-18.0 GHz over -10 dB) can be achieved. The microwave absorption performance of the Fe@AlPO4 composite is indeed superior to pure carbonyl iron as well as many previously reported carbonyl iron-based composites. More importantly, the Fe@AlPO4 composite can maintain good microwave absorption properties after treatment at high temperature for long time periods. These results provide new insight into the fabrication of carbonyl iron-based composites with good microwave absorption and anti-oxidative properties that meet the requirements in practical applications.

  13. Sulfur Isotope Effects of Dissimilatory Sulfite Reductase

    Directory of Open Access Journals (Sweden)

    William D. Leavitt

    2015-12-01

    Full Text Available The precise interpretation of environmental sulfur isotope records requires a quantitative understanding of the biochemical controls on sulfur isotope fractionation by the principle isotope-fractionating process within the S cycle, microbial sulfate reduction (MSR. Here we provide the only direct observation of the major (34S/32S and minor (33S/32S, 36S/32S sulfur isotope fractionations imparted by a central enzyme in the energy metabolism of sulfate reducers, dissimilatory sulfite reductase (DsrAB. Results from in vitro sulfite reduction experiments allow us to calculate the in vitro DsrAB isotope effect in 34S/32S (hereafter, 34εDsrAB to be 15.3±2‰, 2σ. The accompanying minor isotope effect in 33S, described as 33λDsrAB, is calculated to be 0.5150±0.0012, 2σ. These observations facilitate a rigorous evaluation of the isotopic fractionation associated with the dissimilatory MSR pathway, as well as of the environmental variables that govern the overall magnitude of fractionation by natural communities of sulfate reducers. The isotope effect induced by DsrAB upon sulfite reduction is a factor of 0.3 to 0.6 times prior indirect estimates, which have ranged from 25 to 53‰ in 34εDsrAB. The minor isotope fractionation observed from DsrAB is consistent with a kinetic or equilibrium effect. Our in vitro constraints on the magnitude of 34εDsrAB is similar to the median value of experimental observations compiled from all known published work, where 34εr-p = 16.1‰ (r – p indicates reactant versus product, n = 648. This value closely matches those of MSR operating at high sulfate reduction rates in both laboratory chemostat experiments (34εSO4-H2S = 17.3±1.5‰ and in modern marine sediments (34εSO4-H2S = 17.3±3.8‰. Targeting the direct isotopic consequences of a specific enzymatic processes is a fundamental step toward a biochemical foundation for reinterpreting the biogeochemical and geobiological sulfur isotope records in modern

  14. Mitochondrial Thioredoxin-Glutathione Reductase from Larval Taenia crassiceps (Cysticerci

    Directory of Open Access Journals (Sweden)

    Alberto Guevara-Flores

    2010-01-01

    Full Text Available Mitochondrial thioredoxin-glutathione reductase was purified from larval Taenia crassiceps (cysticerci. The preparation showed NADPH-dependent reductase activity with either thioredoxin or GSSG, and was able to perform thiol/disulfide exchange reactions. At 25∘C specific activities were 437  ±  27 mU mg-1 and 840  ±  49 mU mg-1 with thioredoxin and GSSG, respectively. Apparent Km values were 0.87  ±  0.04  μM, 41  ±  6  μM and 19  ±  10  μM for thioredoxin, GSSG and NADPH, respectively. Thioredoxin from eukaryotic sources was accepted as substrate. The enzyme reduced H2O2 in a NADPH-dependent manner, although with low catalytic efficiency. In the presence of thioredoxin, mitochondrial TGR showed a thioredoxin peroxidase-like activity. All disulfide reductase activities were inhibited by auranofin, suggesting mTGR is dependent on selenocysteine. The reductase activity with GSSG showed a higher dependence on temperature as compared with the DTNB reductase activity. The variation of the GSSG- and DTNB reductase activities on pH was dependent on the disulfide substrate. Like the cytosolic isoform, mTGR showed a hysteretic kinetic behavior at moderate or high GSSG concentrations, but it was less sensitive to calcium. The enzyme was able to protect glutamine synthetase from oxidative inactivation, suggesting that mTGR is competent to contend with oxidative stress.

  15. Prothrombin and fibrinogen carbonylation: How that can affect the blood clotting.

    Science.gov (United States)

    Harutyunyan, Hayk A

    2017-07-01

    The aim of the work was the development of a simple method for measuring the plasma prothrombin carbonylation and the study the impact of prothrombin and fibrinogen oxidation on the rate of plasma clotting. A new method was based on the ability of prothrombin to be adsorbed by the barium sulfate. It consists of four steps: prothrombin mixing with the water suspension of BaSO4; reaction of 2,4-dinitrophenylhydrazine with the BaSO4-bound prothrombin; desorption of prothrombin-2,4-dinitrophenylhydrazone complex from BaSO4 in an alkaline medium; neutralization and reading of the optical absorbance of the complex (λ = 370 nm). The prothrombin/fibrinogen carbonylation and plasma clotting rate in vitro in the presence of reactive oxygen species (ROS)-generating agents (0.05-0.8 mM Fe2+/H2O2) were monitored. The plasma volume required for measurement of carbonylated prothrombin was 0.4 ml. High level of linearity and reproducibility was observed (r = 0.9995, P = 0.0005 - for the protein; r = 0.9971, P = 0.0029 - for carbonyls). In the intact rats, the concentration of blood plasma prothrombin was 0.355 ± 0.009 mg/ml, and that of carbonyls was 4.94 ± 0.09 nmol/mg. Prothrombin and plasma clotting rate was not affected by low concentrations of ROS (0.05-0.2 mM Fe2+/H2O2). The fibrinogen was susceptible to ROS-related effect over all the used range of concentration (0.05-0.8 mM Fe2+/H2O2). Carbonylation of fibrinogen did not affect the plasma clotting activity at low ROS concentration (0.05-0.2 mM Fe2+/H2O2), however it retarded the clotting at higher ROS (0.2-0.8 mM Fe2+/H2O2).

  16. Plasmid-encoded diacetyl (acetoin) reductase in Leuconostoc pseudomesenteroides

    DEFF Research Database (Denmark)

    Rattray, Fergal P; Myling-Petersen, Dorte; Larsen, Dianna

    2003-01-01

    ) reductases reported previously. Downstream of the butA gene of L. pseudomesenteroides, but coding in the opposite orientation, a putative DNA recombinase was identified. A two-step PCR approach was used to construct FPR02, a butA mutant of the wild-type strain, CHCC2114. FPR02 had significantly reduced......A plasmid-borne diacetyl (acetoin) reductase (butA) from Leuconostoc pseudomesenteroides CHCC2114 was sequenced and cloned. Nucleotide sequence analysis revealed an open reading frame encoding a protein of 257 amino acids which had high identity at the amino acid level to diacetyl (acetoin...

  17. NITRATE REDUCTASE ACTIVITY DURING HEAT SHOCK IN WINTER WHEAT

    Directory of Open Access Journals (Sweden)

    Klimenko S.B.

    2006-03-01

    Full Text Available Nitrates are the basic source of nitrogen for the majority of plants. Absorption and transformation of nitrates in plants are determined by external conditions and, first of all, temperature and light intensity. The influence of the temperature increasing till +40 0С on activity of nitrate reductase was studied. It is shown, that the rise of temperature was accompanied by sharp decrease of activity nitrate reductase in leaves of winter wheat, what, apparently, occurred for the account deactivations of enzyme and due to its dissociation.

  18. Synthesis and characterization of potent inhibitors of Trypanosoma cruzi dihydrofolate reductase

    Energy Technology Data Exchange (ETDEWEB)

    Schormann, Norbert; Velu, Sadanandan E.; Murugesan, Srinivasan; Senkovich, Olga; Walker, Kiera; Chenna, Bala C.; Shinkre, Bidhan; Desai, Amar; Chattopadhyay, Debasish (UAB)

    2010-09-17

    Dihydrofolate reductase (DHFR) of the parasite Trypanosoma cruzi (T. cruzi) is a potential target for developing drugs to treat Chagas disease. We have undertaken a detailed structure-activity study of this enzyme. We report here synthesis and characterization of six potent inhibitors of the parasitic enzyme. Inhibitory activity of each compound was determined against T. cruzi and human DHFR. One of these compounds, ethyl 4-(5-[(2,4-diamino-6-quinazolinyl)methyl]amino-2-methoxyphenoxy)butanoate (6b) was co-crystallized with the bifunctional dihydrofolate reductase-thymidylate synthase enzyme of T. cruzi and the crystal structure of the ternary enzyme:cofactor:inhibitor complex was determined. Molecular docking was used to analyze the potential interactions of all inhibitors with T. cruzi DHFR and human DHFR. Inhibitory activities of these compounds are discussed in the light of enzyme-ligand interactions. Binding affinities of each inhibitor for the respective enzymes were calculated based on the experimental or docked binding mode. An estimated 60-70% of the total binding energy is contributed by the 2,4-diaminoquinazoline scaffold.

  19. Crystal structure of the Trypanosoma cruzi trypanothione reductase.mepacrine complex.

    Science.gov (United States)

    Jacoby, E M; Schlichting, I; Lantwin, C B; Kabsch, W; Krauth-Siegel, R L

    1996-01-01

    The three-dimensional structure of the complex between Trypanosoma cruzi trypanothione reductase (TR) (EC 1.6.4.8) and the antiparasitic drug mepacrine (quinacrine) has been solved at 2.9 angstoms resolution. Mepacrine is a competitive inhibitor of TR but does not affect human glutathione reductase (GR), a closely related host enzyme. Of particular importance for inhibitor binding are four amino acid residues in the disulfide substrate-binding site of TR that are not conserved in human GR, namely, Glu-18 (Ala-34 in GR), Trp-21 (Arg-37), Ser-109 (Ile-113), and Met-113 (Asn-117). The acridine ring of mepacrine is fixed at the active site close to the hydrophobic wall formed by Trp-21 and Met-113. Specific pairwise interactions between functional groups of the drug and amino acid side chains include the ring nitrogen and Met-113, the chlorine atom and Trp-21, and the oxymethyl group and Ser-109. The alkylamino chain of mepacrine points into the inner region of the active site and is held in position by a solvent-mediated hydrogen bond to Glu-18. The structure of the complex shows for the first time the atomic interactions between TR and an inhibitory ligand. This is a crucial step towards the rational design of inhibitors that might be suited as drugs against Chagas' disease.

  20. Recherches récentes sur le cobalt carbonyle et ses dérivés Recent Studies of Cobalt Carbonyl and Its Derivatives

    Directory of Open Access Journals (Sweden)

    Poilblanc R.

    2006-11-01

    Full Text Available Faisant le point sur l'ensemble de leurs résultats obtenus au cours des dernières années, les auteurs développent divers aspects relatifs aux synthèses, à la physico-chimie et aux structures des complexes dérivés des cobalt carbonyle. L'étude concerne essentiellement : - les dérivés de simple substitution de l'octacarbonyle dicobalt et la tautomérie des complexes dinucléaires; - les dérivés mononucléaires ioniques et leur relation avec les formes alkyle et acétyle du cobalt (I; - le bis (tétracarbonyle cobalt mercure et ses dérivés de substitution ; - les dérivés tétranucléaires et le phénomène de « migration intramoléculaire » des ligands. Les caractéristiques spectrographiques de quelque soixante-dix complexes sont fournies en annexe. The authors review their findings concerning the synthesis, physico-chemical properties and structural nature of cobalt carbonyl derivatives. The article deals with : - Normal substitution of Col (CO,, and tautomerism of binuclear complexes; - lonic mononuclear derivatives in relation with alkyl and acetylcobaltcarbonyls ; - Bis (tetracarbonylcobalt mercury and its substituted derivatives ; - Tetranuclear cobalt complexes exhibiting intramolecular scrambling. Spectrographic data of some 70 compounds are given.

  1. Design and fabrication of microfluidic mixer from carbonyl iron–PDMS composite membrane

    KAUST Repository

    Li, Jiaxing

    2010-10-12

    This paper introduces a carbonyl iron-PDMS (CI-PDMS) composite magnetic elastomer in which carbonyl iron (CI) particles are uniformly distributed in a PDMS matrix. The CI particles and the PDMS were mixed at different weight ratios and tested to determine the influence of CI concentration. The magnetic and mechanical properties of the magnetic elastomers were characterized, respectively, by vibrating-sample magnetometer and by tensile testing using a mechanical analyzer. The elastomer was found to exhibit high magnetization and good mechanical flexibility. The morphology and deformation of the CI-PDMS membrane also were observed. A magnetically actuated microfluidic mixer (that is, a micromixer) integrated with CI-PDMS elastomer membranes was successfully designed and fabricated. The high efficiency and quality of the mixing makes possible the impressive potential applications of this unique CI-PDMS material in microfluidic systems. © Springer-Verlag 2010.

  2. Analysis of protein carbonylation - pitfalls and promise in commonly used methods

    DEFF Research Database (Denmark)

    Rogowska-Wrzesinska, A.; Wojdyla, K.; Nedic, O.

    2014-01-01

    that research scientists are becoming more eager to be able to measure accurately the level of oxidized protein in biological materials, and to determine the precise site of the oxidative attack on the protein, in order to get insights into the molecular mechanisms involved in the progression of diseases....... Several methods for measuring protein carbonylation have been implemented in different laboratories around the world. However, to date no methods prevail as the most accurate, reliable, and robust. The present paper aims at giving an overview of the common methods used to determine protein carbonylation...... in biological material as well as to highlight the limitations and the potential. The ultimate goal is to give quick tips for a rapid decision making when a method has to be selected and taking into consideration the advantage and drawback of the methods....

  3. Analysis of protein carbonylation-pitfalls and promise in commonly used methods

    DEFF Research Database (Denmark)

    Rogowska-Wrzesinska, Adelina; Wojdyla, K; Nedić, O

    2014-01-01

    that research scientists are becoming more eager to be able to measure accurately the level of oxidized protein in biological materials, and to determine the precise site of the oxidative attack on the protein, in order to get insights into the molecular mechanisms involved in the progression of diseases....... Several methods for measuring protein carbonylation have been implemented in different laboratories around the world. However, to date no methods prevail as the most accurate, reliable, and robust. The present paper aims at giving an overview of the common methods used to determine protein carbonylation...... in biological material as well as to highlight the limitations and the potential. The ultimate goal is to give quick tips for a rapid decision making when a method has to be selected and taking into consideration the advantage and drawback of the methods....

  4. Auranofin inactivates Trichomonas vaginalis thioredoxin reductase and is effective against trichomonads in vitro and in vivo.

    Science.gov (United States)

    Hopper, Melissa; Yun, Jeong-Fil; Zhou, Bianhua; Le, Christine; Kehoe, Katelin; Le, Ryan; Hill, Ryan; Jongeward, Gregg; Debnath, Anjan; Zhang, Liangfang; Miyamoto, Yukiko; Eckmann, Lars; Land, Kirkwood M; Wrischnik, Lisa A

    2016-12-01

    Trichomoniasis, caused by the protozoan parasite Trichomonas vaginalis, is the most common, non-viral, sexually transmitted infection in the world, but only two closely related nitro drugs are approved for its treatment. New antimicrobials against trichomoniasis remain an urgent need. Several organic gold compounds were tested for activity against T. vaginalis thioredoxin reductase (TrxR) in cell-free systems as well as for activity against different trichomonads in vitro and in a murine infection model. The organic gold(I) compounds auranofin and chloro(diethylphenylphosphine)gold(I) inhibited TrxR in a concentration-dependent manner in assays with recombinant purified reductase and in cytoplasmic extracts of T. vaginalis transfected with a haemagglutinin epitope-tagged form of the reductase. Auranofin potently suppressed the growth of three independent clinical T. vaginalis isolates as well as several strains of another trichomonad (Tritrichomonas foetus) in a 24 h-assay, with 50% inhibitory concentrations of 0.7-2.5 µM and minimum lethal concentrations of 2-6 µM. The drug also compromised the ability of the parasite to overcome oxidant stress, supporting the notion that auranofin acts, in part, by inactivating TrxR-dependent antioxidant defences. Chloro(diethylphenylphosphine)gold(I) was 10-fold less effective against T. vaginalis in vitro than auranofin. Oral administration of auranofin for 4 days cleared the parasites in a murine model of vaginal T. foetus infection without displaying any apparent adverse effects. The approved human drug auranofin may be a promising agent as an alternative treatment of trichomoniasis in cases when standard nitro drug therapies have failed. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  5. X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Pegan, Scott D.; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A.; Mesecar, Andrew D. (IdRS); (Purdue); (Colorado); (UIC)

    2011-09-06

    Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC{sub 50} values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

  6. X-ray structural studies of quinone reductase 2 nanomolar range inhibitors.

    Science.gov (United States)

    Pegan, Scott D; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A; Mesecar, Andrew D

    2011-07-01

    Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC₅₀ values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands. Copyright © 2011 The Protein Society.

  7. Thioredoxin glutathione reductase as a novel drug target: evidence from Schistosoma japonicum.

    Directory of Open Access Journals (Sweden)

    LiJun Song

    Full Text Available BACKGROUND: Schistosomiasis remains a major public health concern affecting billions of people around the world. Currently, praziquantel is the only drug of choice for treatment of human schistosomiasis. The emergence of drug resistance to praziquantel in schistosomes makes the development of novel drugs an urgent task. Thioredoxin glutathione reductase (TGR enzymes in Schistosoma mansoni and some other platyhelminths have been identified as alternative targets. The present study was designed to confirm the existense and the potential value of TGR as a target for development of novel antischistosomal agents in Schistosoma japonicum, a platyhelminth endemic in Asia. METHODS AND FINDINGS: After cloning the S. japonicum TGR (SjTGR gene, the recombinant SjTGR selenoprotein was purified and characterized in enzymatic assays as a multifunctional enzyme with thioredoxin reductase (TrxR, glutathione reductase (GR and glutaredoxin (Grx activities. Immunological and bioinformatic analyses confirmed that instead of having separate TrxR and GR proteins in mammalian, S. japonicum only encodes TGR, which performs the functions of both enzymes and plays a critical role in maintaining the redox balance in this parasite. These results were in good agreement with previous findings in Schistosoma mansoni and some other platyhelminths. Auranofin, a known inhibitor against TGR, caused fatal toxicity in S. japonicum adult worms in vitro and reduced worm and egg burdens in S. japonicum infected mice. CONCLUSIONS: Collectively, our study confirms that a multifunctional enzyme SjTGR selenoprotein, instead of separate TrxR and GR enzymes, exists in S. japonicum. Furthermore, TGR may be a potential target for development of novel agents against schistosomes. This assumption is strengthened by our demonstration that the SjTGR is an essential enzyme for maintaining the thiol-disulfide redox homeostasis of S. japonicum.

  8. Dicarbonyl L-xylulose reductase (DCXR, a "moonlighting protein" in the bovine epididymis.

    Directory of Open Access Journals (Sweden)

    Ayodélé Akintayo

    Full Text Available During maturation and the acquisition of their fertilization potential, male germ cells are subjected to various sequential modifications that occur in the epididymis. Protein addition, reorganization or withdrawal, comprise some of these modifications. Dicarbonyl L-xylulose reductase (DCXR, a multifunctional protein involved in various enzymatic and protein interaction processes in different physiological systems, is one of the proteins added to spermatozoa in the epididymis. DCXR is a well-conserved protein with multiple characteristics including enzymatic activities and mediation of cell-cell interaction. In this study, we characterized the DCXR gene and protein expression in the bovine epididymis. Dicarbonyl L-xylulose reductase mRNA is differentially expressed in the caput, corpus, and cauda epididymide epithelial cells with a higher level observed in the cauda region. Tissue protein expression follows the same pattern as the corresponding mRNA expression with a cytoplasmic and apical distribution in the corpus and cauda epithelial cells, respectively. The protein can also be found with a nuclear localization in cauda epididymidis epithelial cells. Dicarbonyl L-xylulose reductase is secreted in the epididymis luminal compartment in the soluble fraction and is associated with microvesicular elements named epididymosomes. In spermatozoa, the DCXR protein was found in the cytoplasmic and membranous fractions. Expression of the DCXR protein is higher on caput spermatozoa but finally shows a weak detection in semen. These data describe DCXR in the bovine epididymis and reveal that its behavior differs from that found in humans. It seems that, in this model, the DCXR protein might have a questionable involvement in the fertilization process.

  9. Thioredoxin and Its Reductase Are Present on Synaptic Vesicles, and Their Inhibition Prevents the Paralysis Induced by Botulinum Neurotoxins

    Directory of Open Access Journals (Sweden)

    Marco Pirazzini

    2014-09-01

    Full Text Available Botulinum neurotoxins consist of a metalloprotease linked via a conserved interchain disulfide bond to a heavy chain responsible for neurospecific binding and translocation of the enzymatic domain in the nerve terminal cytosol. The metalloprotease activity is enabled upon disulfide reduction and causes neuroparalysis by cleaving the SNARE proteins. Here, we show that the thioredoxin reductase-thioredoxin protein disulfide-reducing system is present on synaptic vesicles and that it is functional and responsible for the reduction of the interchain disulfide of botulinum neurotoxin serotypes A, C, and E. Specific inhibitors of thioredoxin reductase or thioredoxin prevent intoxication of cultured neurons in a dose-dependent manner and are also very effective inhibitors of the paralysis of the neuromuscular junction. We found that this group of inhibitors of botulinum neurotoxins is very effective in vivo. Most of them are nontoxic and are good candidates as preventive and therapeutic drugs for human botulism.

  10. Deoxynucleoside salvage in fission yeast allows rescue of ribonucleotide reductase deficiency but not Spd1-mediated inhibition of replication

    DEFF Research Database (Denmark)

    Fleck, Oliver; Fahnøe, Ulrik; Løvschal, Katrine Vyff

    2017-01-01

    In fission yeast, the small, intrinsically disordered protein S-phase delaying protein 1 (Spd1) blocks DNA replication and causes checkpoint activation at least in part, by inhibiting the enzyme ribonucleotide reductase, which is responsible for the synthesis of DNA. The CRL4(Cdt2) E3 ubiquitin...... triphosphate (dNTP) pools; yet we find that Spd1 and Spd2 together inhibit DNA replication upon Cdt2 depletion. To directly test whether this block of replication was solely due to insufficient dNTP levels, we established a deoxy-nucleotide salvage pathway in fission yeast by expressing the human nucleoside...... ribonucleotide reductase. However, salvage completely failed to rescue S phase delay, checkpoint activation, and damage sensitivity, which was caused by CRL4(Cdt2) inactivation, suggesting that Spd1-in addition to repressing dNTP synthesis-together with Spd2, can inhibit other replication functions. We propose...

  11. Characterization of Carbonyl Compounds in the Ambient Air of an Industrial City in Korea

    Directory of Open Access Journals (Sweden)

    Sung-Ok Baek

    2011-01-01

    Full Text Available The purpose of this study was to characterize spatial and temporal variations of carbonyl compounds in Gumi city, where a number of large electronic-industrial complexes are located. Carbonyl samples were collected at five sites in the Gumi area: three industrial, one commercial, and one residential area. Sampling was carried out throughout a year from December 2003 to November 2004. At one industrial site, samples were taken every six days, while those of the other sites were for seven consecutive days in every season. Each sample was collected for 150 minutes and at intervals of three times a day (morning, afternoon, and evening. A total of 476 samples were analyzed to determine 15 carbonyl compounds by the USEPA TO-11A (DNPH-cartridge/HPLC method. In general, acetaldehyde appeared to be the most abundant compound, followed by formaldehyde, and acetone+acrolein. Mean concentrations of acetaldehyde were two to three times higher in the industrial sites than in the other sites, with its maximum of 77.7 ppb. In contrast, ambient levels of formaldehyde did not show any significant difference between the industrial and non-industrial groups. Its concentrations peaked in summer probably due to the enhanced volatilization and photochemical reactivity. These results indicate significant emission sources of acetaldehyde in the Gumi industrial complexes. Mean concentrations of organic solvents (such as acetone+acrolein and methyl ethyl ketone were also significantly high in industrial areas. In conclusion, major sources of carbonyl compounds, including acetaldehyde, are strongly associated with industrial activities in the Gumi city area.

  12. Carbonylative Heck Reactions Using CO Generated ex Situ in a Two-Chamber System

    DEFF Research Database (Denmark)

    Hermange, Philippe; Gøgsig, Thomas; Lindhardt, Anders Thyboe

    2011-01-01

    A carbonylative Heck reaction of aryl iodides and styrene derivatives employing a two-chamber system using a stable, crystalline, and nontransition metal based carbon monoxide source is reported. By applying near-stoichiometric amounts of the carbon monoxide precursor, an effective exploitation o...... of the hazardous CO gas is obtained affording chalcone derivatives in good yields. Application to isotope labeling, incorporating 13CO, was further established....

  13. The magnetorheological fluid of carbonyl iron suspension blended with grafted MWCNT or graphene

    Science.gov (United States)

    Rwei, Syang-Peng; Ranganathan, Palraj; Chiang, Whe-Yi; Wang, Tza-Yi

    2017-12-01

    In this work, the magnetorheological (MR) fluids containing MWCNT/CI (carbonyl iron) complex and graphene/CI complex were prepared and have the better dispersity in silicone oil than CI powders alone. 1, 4-Aminobenzoic acid (PABA) was used as a grafting agent to modify CI powders to have NH2-end-group so that such nanoparticles can adsorb to acid-treated MWCNT or graphene via attraction of NH2 and COOH groups. The MWCNT/CI complex and graphene/CI complex have a structure of carbonyl iron nanoparticles adsorbed to MWCNT and graphene by self assembly, respectively. Because the carbonyl iron particles possessing magnetic permeability in nanometer scale adsorb to MWCNT or graphene which usually has a nanometer-scaled diameter and a micrometer-scaled length in this work, the dispersity of MWCNT/CI or graphene/CI complex in silicone oil is superior than the previous report [15] that the micrometer-scaled carbonyl iron microspheres were coated with multiwalled carbon nanotubes. Among CI (unmodified), MWCNT/CI and graphene/CI, graphene/CI has the best dispersity while MWCNT/CI still has the better dispersity than unmodified CI. At the temperature T = 300 K, the saturation magnetizations of CI, MWCNT/CI, graphene/CI are 208, 211 emu/g, and 204 emu/g, respectively, indicating that MWCNT/CI complex and graphene/CI complex still maintain the saturation magnetization as high as CI without being interfered by the blended MWCNT or graphene. A wide dynamic range of the yield stress adjusted through varying the electric current can be achieved by the MR fluids containing 69 wt% MWCNT/CI and graphene/CI which is useful in a shock absorber or damper. The result of the yield stress indicates the suspended MWCNT/CI particles are oriented more easily toward the direction perpendicular to the flow direction to block the flow stream lines.

  14. An intercomparison of aircraft instrumentation for tropospheric measurements of carbonyl sulfide, hydrogen sulfide, and carbon disulfide

    OpenAIRE

    Gregory, Gerald L; Douglas D. Davis; Thornton, Donald C; James E. Johnson; Bandy, Alan R.; Saltzman, Eric S.; Andreae, Meinrat O.; Barrick, John D

    1993-01-01

    This paper reports results of NASA's Chemical Instrumentation and Test Evaluation (CITE 3) during which airborne measurements for carbonyl sulfide (COS), hydrogen sulfide (H2S), and carbon disulfide (CS2) were intercompared. Instrumentation included a gas chromatograph using flame photometric detection (COS, H2S, and CS2), a gas chromatograph using mass spectrometric detection (COS and CS2), a gas chromatograph using fluorination and subsequent SF6 detection via electron capture (COS and CS2)...

  15. First-row transition metal catalyzed reduction of carbonyl functionalities: a mechanistic perspective.

    Science.gov (United States)

    Chakraborty, Sumit; Guan, Hairong

    2010-08-28

    The use of first-row transition metals for the catalytic reduction of carbonyl functionalities has become increasingly important in homogeneous catalysis. This Perspective examines the mechanistic aspects of these reduction reactions, with a focus on various interactions between metal complexes and substrates. Four different types of catalytic pathways, namely catalysis with dihydride (or dihydrogen) complexes, catalysis with monohydride complexes, metal-ligand bifunctional catalysis, and catalysis involving ionic mechanisms, are discussed with recent examples highlighted.

  16. Bifunctional ligands in combination with phosphines and Lewis acidic phosphonium [corrected] for the carbonylative Sonogashira reaction.

    Science.gov (United States)

    Tan, Chen; Wang, Peng; Liu, Huan; Zhao, Xiao-Li; Lu, Yong; Liu, Ye

    2015-07-11

    The combination of phosphine-ligated Pd catalysis and phosphonium(V) [corrected] Lewis acid catalysis has been developed for the carbonylative Sonogashira reaction using phosphino-phosphonium [corrected] salts (L1-L4) as bifunctional ligands, in which the Lewis acidic phosphonium(V) [corrected] cations can form secondary bonds with O atoms (in C=O) to cooperatively stabilize Pd-acyl intermediates.

  17. The interaction of metal carbonyl compounds with organic polymers and monomers

    OpenAIRE

    Lyons, Michael P.

    1993-01-01

    The photochemistry of W(CO)6, Mo(CO)6, and Cr(CO)6 in the presence of monomeric and polymeric triphenylphosphine ligands was investigated in toluene solution, using laser flash photolysis with 355nm excitation. The mechanism and kinetics of interaction of the primary photoproducts M(CO)5(toluene) (M = W, Mo, or Cr) with the various monomeric ligands were investigated. Interaction of the metal carbonyl photofragments with various homopolymers is also discussed. The polymerisation methods used ...

  18. Rhodium-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Carbonyl Compounds via Thiourea Hydrogen Bonding.

    Science.gov (United States)

    Wen, Jialin; Jiang, Jun; Zhang, Xumu

    2016-09-16

    The strategy of secondary interaction enables enantioselectivity for homogeneous hydrogenation. By introducing hydrogen bonding of substrates with thiourea from the ligand, α,β-unsaturated carbonyl compounds, such as amides and esters, are hydrogenated with high enantiomeric excess. The substrate scope for this chemical transformation is broad with various substituents at the β-position. Control experiments revealed that each unit of the ligand ZhaoPhos is irreplaceable. No nonlinear effect was observed for this Rh/ZhaoPhos-catalyzed asymmetric hydrogenation.

  19. Oxidative and carbonyl stress in pregnant women with obstructive sleep apnea.

    Science.gov (United States)

    Khan, Nazia; Lambert-Messerlian, Geralyn; Monteiro, Joao Filipe; Hodosy, Julius; Tóthová, Ľubomíra; Celec, Peter; Eklund, Elizabeth; Curran, Patrizia; Bourjeily, Ghada

    2017-02-24

    Pregnant women are particularly susceptible to sleep-disordered breathing. Obstructive sleep apnea (OSA) in pregnancy is associated with poor pregnancy and fetal outcomes. Oxidative stress caused by intermittent hypoxemia and reoxygenation may impact pregnancy health. We hypothesize that pregnant women with OSA have a pronounced oxidative stress profile. A case-control study was performed to study oxidative stress markers in the serum of pregnant women with or without OSA. Patients with OSA were identified between 2003 and 2009. Contemporaneous controls were pregnant subjects without apnea, gasping, or snoring around the time of delivery. Serum markers of oxidative and carbonyl stress were measured by spectrophotometric/fluorometric methods. Multiple linear regression analysis was used with a model including age, body mass index at delivery, history of diabetes, and gestational age. Serum samples from 23 OSA cases and 41 controls were identified. Advanced oxidation protein products, a marker for oxidative stress, and advanced glycation end products (AGEs), a marker for carbonyl stress, were significantly lower in women with OSA than in controls (p value oxidative and carbonyl stress markers compared to controls, suggesting a possible protective effect of intermittent hypoxia. Whether OSA in pregnancy impacts oxidative stress differently than OSA in the general population remains to be confirmed.

  20. Synthesis and Characterization of Group-6 Metal Carbonyl Complexes of Aroyl Hydrazone Derivatives

    Directory of Open Access Journals (Sweden)

    Mohd Saleem

    2012-01-01

    Full Text Available Carbonyl complexes of Chromium, molybdenum and tungsten of composition, [M(CO4L-L], (where M= Cr, Mo or W and L-L= benzoic acid[1-(Furan-2-ylmethylene]hydrazide (BFMH, benzoic acid[(thiophene-2-ylmethylene]hydrazide (BTMH, benzoic acid[1-(thiophene-2-ylethylidene] hydrazide (BTEH, benzoic acid (phenylmethylenehydrazide (BPMH and benzoic acid[1-(anisol-3-ylmethylene] hydrazide (BAMH are reported. These have been prepared by refluxing metal carbonyls and the ligands in 1:1molar ratio. The complexes were characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR, TGA/DTA, conductivity and magnetic susceptibility measurements. The IR bands suggest that in all the complexes the ligands behave as neutral bidentate chelating type coordinating metal through carbonyl oxygen and azomethine nitrogen. The CO force constants and CO-CO interaction constants for these derivatives have been calculated using Cotton-Kraihanzel secular equations, which indicate poor π-bonding ability of the coordinated ligands.

  1. Incorporating conjugated carbonyl compounds into carbon nanomaterials as electrode materials for electrochemical energy storage.

    Science.gov (United States)

    Yang, Guanhui; Zhang, Yu; Huang, Yanshan; Shakir, Muhammad Imran; Xu, Yuxi

    2016-11-23

    The increasing demand for energy and growing concerns for environmental issues are promoting the development of organic electrode materials. Among these, conjugated carbonyl compounds (CCCs) represent one of the most attractive and promising candidates for sustainable and eco-benign energy storage devices in the coming future. However, most of the current compounds suffer from dissolution in organic electrolytes and low electronic conductivity, which result in severe capacity decay and poor rate performance. Recently, researchers have achieved considerable progress by introducing electroactive carbonyl compounds into carbon nanomaterials. This perspective provides an overview of the up-to-date development of these nanocomposites in metal ion batteries (lithium-ion batteries or sodium-ion batteries) and supercapacitors (SCs), including the synthesis, performance improvement and applications. We mainly focus on carbon nanotubes (CNTs), graphene and mesoporous carbon (MC) as carbon nanomaterials because of their high specific surface area, good conductivity, electrochemical stability and favourable interaction with conjugated carbonyl compounds. This strategy opens up new possibilities to realize cost-effective, sustainable and versatile energy storage devices.

  2. Protein carbonyls are acutely elevated following single set anaerobic exercise in resistance trained men.

    Science.gov (United States)

    Bloomer, Richard J; Fry, Andrew C; Falvo, Michael J; Moore, Christopher A

    2007-12-01

    The purpose of this investigation was to determine if a single set of strenuous squat exercise would result in an acute oxidative stress, as demonstrated previously by a single sprint. Thirteen resistance trained men performed one set of 15 repetitions of barbell squats using 70% of one repetition maximum and a 30 s maximal cycle sprint on two different occasions. The total work performed was calculated for each exercise bout. Heart rate, perceived exertion, blood lactate, protein carbonyls, 8-hydroxydeoxyguanosine, and malondialdehyde were measured before and within 1 min following exercise. No differences were noted between the squat and sprint tests for total work, heart rate or perceived exertion. An exercise test by time interaction was evident for blood lactate with values greater following sprinting compared to squatting (P=0.0005). Postexercise protein carbonyls were not different between exercise tests but were elevated above rest (P=0.04) by 111% and 74% following sprinting and squatting, respectively, while 8-hydroxydeoxyguanosine and malondialdehyde were relatively unaffected by either exercise test. These data indicate that a single bout of strenuous squatting and sprinting performed by resistance trained men results in elevated protein carbonyls, while having little impact on 8-hydroxydeoxyguanosine or malondialdehyde during the immediate postexercise period.

  3. A new structural arrangement in proteins involving lysine NH3+ group and carbonyl.

    Science.gov (United States)

    Rogacheva, Olga N; Izmailov, Sergei A; Slipchenko, Lyudmila V; Skrynnikov, Nikolai R

    2017-11-27

    Screening of the Protein Data Bank led to identification of a recurring structural motif where lysine NH3+ group interacts with backbone carbonyl. This interaction is characterized by linear atom arrangement, with carbonyl O atom positioned on the three-fold symmetry axis of the NH3+ group (angle Cε-Nζ-O close to 180°, distance Nζ-O ca. 2.7-3.0 Å). Typically, this linear arrangement coexists with three regular hydrogen bonds formed by lysine NH3+ group (angle Cε-Nζ-acceptor atom close to 109°, distance Nζ-acceptor atom ca. 2.7-3.0 Å). Our DFT calculations using polarizable continuum environment suggest that this newly identified linear interaction makes an appreciable contribution to protein's energy balance, up to 2 kcal/mol. In the context of protein structure, linear interactions play a role in capping the C-termini of α-helices and 310-helices. Of note, linear interaction involving conserved lysine is consistently found in the P-loop of numerous NTPase domains, where it stabilizes the substrate-binding conformation of the P-loop. Linear interaction NH3+ - carbonyl represents an interesting example of ion-dipole interactions that has so far received little attention compared to ion-ion interactions (salt bridges) and dipole-dipole interactions (hydrogen bonds), but nevertheless represents a distinctive element of protein architecture.

  4. Ultrafast carbonyl motion of the photoactive yellow protein chromophore probed by femtosecond circular dichroism.

    Science.gov (United States)

    Mendonça, Lucille; Hache, François; Changenet-Barret, Pascale; Plaza, Pascal; Chosrowjan, Haik; Taniguchi, Seiji; Imamoto, Yasushi

    2013-10-02

    Motions of the trans-p-coumaric acid carbonyl group following the photoexcitation of the R52Q mutant of photoactive yellow protein (PYP) are investigated, for the first time, by ultrafast time-resolved circular dichroism (TRCD) spectroscopy. TRCD is monitored in the near-ultraviolet, over a time scale of 10 ps. Immediately after excitation, TRCD is found to exhibit a large negative peak, which decays within a few picoseconds. A quantitative analysis of the signals shows that, upon excitation, the carbonyl group undergoes a fast (≪0.8 ps) and unidirectional flipping motion in the excited state with an angle of ca. 17-53°. For the subset of proteins that do not enter the signaling photocycle, TRCD provides strong evidence that the carbonyl group moves back to its initial position, leading to the formation of a nonreactive ground-state intermediate of trans conformation. The initial ground state is then restored within ca. 3 ps. Comparative study of R52Q and wild-type PYP provides direct evidence that the absence of Arg52 has no effect on the conformational changes of the chromophore during those steps.

  5. Profiling Carbonylated Proteins in Heart and Skeletal Muscle Mitochondria from Trained and Untrained Mice.

    Science.gov (United States)

    Carpentieri, Andrea; Gamberi, Tania; Modesti, Alessandra; Amoresano, Angela; Colombini, Barbara; Nocella, Marta; Bagni, Maria Angela; Fiaschi, Tania; Barolo, Lorenzo; Gulisano, Massimo; Magherini, Francesca

    2016-10-07

    Understanding the relationship between physical exercise, reactive oxygen species, and skeletal muscle modification is important in order to better identify the benefits or the damages that appropriate or inappropriate exercise can induce. Heart and skeletal muscles have a high density of mitochondria with robust energetic demands, and mitochondria plasticity has an important role in both the cardiovascular system and skeletal muscle responses. The aim of this study was to investigate the influence of regular physical activity on the oxidation profiles of mitochondrial proteins from heart and tibialis anterior muscles. To this end, we used the mouse as animal model. Mice were divided into two groups: untrained and regularly trained. The carbonylated protein pattern was studied by two-dimensional gel electrophoresis followed by Western blot with anti-dinitrophenyl hydrazone antibodies. Mass spectrometry analysis allowed the identification of several different protein oxidation sites, including methionine, cysteine, proline, and leucine residues. A large number of oxidized proteins were found in both untrained and trained animals. Moreover, mitochondria from skeletal muscles and heart showed almost the same carbonylation pattern. Interestingly, exercise training seems to increase the carbonylation level mainly of mitochondrial proteins from skeletal muscle.

  6. Molecular Cloning and Expression of Bacterial Mercuric Reductase ...

    African Journals Online (AJOL)

    In order to characterize the bacterial mercuric reductase (merA) gene, mercury resistant (Hgr) Escherichia coli strains have been isolated from various mercury contaminated sites of India. Their minimum inhibitory concentration (MIC) for Hg and zone of inhibition for different antibiotics were measured, and finally mer operon ...

  7. Transcriptional modulation of genes encoding nitrate reductase in ...

    African Journals Online (AJOL)

    2016-10-26

    Oct 26, 2016 ... The free aluminum (Al) content in soil can reach levels that are toxic to plants, and this has frequently limited increased productivity of cultures. Four genes encoding nitrate reductase (NR) were identified, named ZmNR1–4. With the aim of evaluating NR activity and the transcriptional modulation of the.

  8. Sepiapterin reductase deficiency : A Treatable Mimic of Cerebral Palsy

    NARCIS (Netherlands)

    Friedman, Jennifer; Roze, Emmanuel; Abdenur, Jose E.; Chang, Richard; Gasperini, Serena; Saletti, Veronica; Wali, Gurusidheshwar M.; Eiroa, Hernan; Neville, Brian; Felice, Alex; Parascandalo, Ray; Zafeiriou, Dimitrios I.; Arrabal-Fernandez, Luisa; Dill, Patricia; Eichler, Florian S.; Echenne, Bernard; Gutierrez-Solana, Luis G.; Hoffmann, Georg F.; Hyland, Keith; Kusmierska, Katarzyna; Tijssen, Marina A. J.; Lutz, Thomas; Mazzuca, Michel; Penzien, Johann; Bwee Tien Poll-The, [No Value; Sykut-Cegielska, Jolanta; Szymanska, Krystyna; Thoeny, Beat; Blau, Nenad

    Objective: Sepiapterin reductase deficiency (SRD) is an under-recognized levodopa-responsive disorder. We describe clinical, biochemical, and molecular findings in a cohort of patients with this treatable condition. We aim to improve awareness of the phenotype and available diagnostic and

  9. Cloning and characterization of a nitrite reductase gene related to ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-01

    Mar 1, 2010 ... somatic embryogenesis stages, and that the level of GhNiR mRNA was also higher in the cultivar with higher somatic ..... Planta, 183: 17-24. Alexander H, Treusch, Sven L, Arnulf K, Stephan CS, Hans-Peter K,. Christa S (2005). Novel genes for nitrite reductase and Amo-related proteins indicate a role of ...

  10. Xylose reductase from the thermophilic fungus Talaromyces emersonii

    Indian Academy of Sciences (India)

    Prakash

    National University of Ireland, Galway, University Road, Galway, Ireland. 2Shannon Applied Biotechnology Centre, Limerick Institute Technology, Moylish Park, Limerick, Ireland. *Corresponding authors (Fax, 0035361208208; Email, patrick.murray@lit.ie). Xylose reductase is involved in the first step of the fungal pentose ...

  11. Dizygotic twinning is not associated with methylenetetrahydrofolate reductase haplotypes

    NARCIS (Netherlands)

    Montgomery, GW; Zhao, Z.Z.; Morley, K.I.; Marsh, A.J.; Boomsma, D.I.; Martin, N.G.; Duffy, DL

    2003-01-01

    Background: Folate metabolism is critical to embryonic development, influencing neural tube defects (NTD) and recurrent early pregnancy loss. Polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR) have been associated with dizygotic (DZ) twinning through pregnancy loss. Methods: The C677T

  12. Bioinformatic analysis of dihydrofolate reductase predicted in the ...

    African Journals Online (AJOL)

    olayemitoyin

    Bioinformatic analysis of dihydrofolate reductase predicted in the genome sequence of Lactobacillus pentosus KCA1. *Kingsley C. Anukam. 1 and Uche Oge. 2. 1TWAS Genomic Research Unit, Department of Medical Laboratory Science, 2Department of Physiology,. School of Basic Medical Sciences, University of Benin, ...

  13. Bioinformatic analysis of dihydrofolate reductase predicted in the ...

    African Journals Online (AJOL)

    The genome has open reading frames coding for the complete genes required for folate biosynthesis. Our previous study shows that rats fed with L. pentosus KCA1 led to enhancement of haematological parameters. Bioinformatic tool such as ClustalW algorithm was used to analyze dihydrofolate reductase (folA/dfrA) ...

  14. Optimum conditions for cotton nitrate reductase extraction and ...

    African Journals Online (AJOL)

    Conditions of nitrate reductase extraction and activity measurement should be adapted to plant species, and to the organs of the same plant, because of extreme weaknesses and instabilities of the enzyme. Different extraction and reaction media have been compared in order to define the best conditions for cotton callus ...

  15. Transcriptional modulation of genes encoding nitrate reductase in ...

    African Journals Online (AJOL)

    The free aluminum (Al) content in soil can reach levels that are toxic to plants, and this has frequently limited increased productivity of cultures. Four genes encoding nitrate reductase (NR) were identified, named ZmNR1–4. With the aim of evaluating NR activity and the transcriptional modulation of the ZmNR1, ZmNR2, ...

  16. Cloning and expression analysis of dihydroxyflavonol 4-reductase ...

    African Journals Online (AJOL)

    Dihydroflavonol 4-reductase (DFR) gene is a key gene of anthocyanins biosynthesis pathway, which represent an importance pathway for orchid flower. In this study, cloning and expression analysis of DFR gene in Ascocenda spp. were carried out. Nucleotide analysis revealed that the Ascocenda DFR gene was 1,056 bp ...

  17. Aldose Reductase Inhibitory and Antiglycation Activities of Four ...

    African Journals Online (AJOL)

    Thonn., Punica granatum L., and Stevia rebaudiana Bertoni) standardized extracts and their major constituents (morusin, phyllanthin, punicalagin and stevioside) in the treatment of long-term diabetic complications by inhibition of aldose reductase (AR) enzyme and advanced glycation end products (AGEs) formation.

  18. Yttrium (III chloride catalyzed Mannich reaction: An efficient procedure for the synthesis of β-amino carbonyl compounds

    Directory of Open Access Journals (Sweden)

    Venkateswarlu Yekkirala

    2014-12-01

    Full Text Available Yttrium (III chloride catalyzed Mannich reaction of aldehydes with ketones and amines in acetonitrile at reflux temperature to give various β-amino carbonyl compounds in very good yields.

  19. The Polymorphisms in Methylenetetrahydrofolate Reductase, Methionine Synthase, Methionine Synthase Reductase, and the Risk of Colorectal Cancer

    Science.gov (United States)

    Zhou, Daijun; Mei, Qiang; Luo, Han; Tang, Bo; Yu, Peiwu

    2012-01-01

    Polymorphisms in genes involved in folate metabolism may modulate the risk of colorectal cancer (CRC), but data from published studies are conflicting. The current meta-analysis was performed to address a more accurate estimation. A total of 41 (17,552 cases and 26,238 controls), 24(8,263 cases and 12,033 controls), 12(3,758 cases and 5,646 controls), and 13 (5,511 cases and 7,265 controls) studies were finally included for the association between methylenetetrahydrofolate reductase (MTHFR) C677T and A1289C, methione synthase reductase (MTRR) A66G, methionine synthase (MTR) A2756G polymorphisms and the risk of CRC, respectively. The data showed that the MTHFR 677T allele was significantly associated with reduced risk of CRC (OR = 0.93, 95%CI 0.90-0.96), while the MTRR 66G allele was significantly associated with increased risk of CRC (OR = 1.11, 95%CI 1.01-1.18). Sub-group analysis by ethnicity revealed that MTHFR C677T polymorphism was significantly associated with reduced risk of CRC in Asians (OR = 0.80, 95%CI 0.72-0.89) and Caucasians (OR = 0.84, 95%CI 0.76-0.93) in recessive genetic model, while the MTRR 66GG genotype was found to significantly increase the risk of CRC in Caucasians (GG vs. AA: OR = 1.18, 95%CI 1.03-1.36). No significant association was found between MTHFR A1298C and MTR A2756G polymorphisms and the risk of CRC. Cumulative meta-analysis showed no particular time trend existed in the summary estimate. Probability of publication bias was low across all comparisons illustrated by the funnel plots and Egger's test. Collectively, this meta-analysis suggested that MTHFR 677T allele might provide protection against CRC in worldwide populations, while MTRR 66G allele might increase the risk of CRC in Caucasians. Since potential confounders could not be ruled out completely, further studies were needed to confirm these results. PMID:22719222

  20. Spatial distributions of and diurnal variations in low molecular weight carbonyl compounds in coastal seawater, and the controlling factors

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Kazuhiko, E-mail: takedaq@hiroshima-u.ac.jp [Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521 (Japan); Katoh, Shinya; Mitsui, Yumi; Nakano, Shinichi [Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521 (Japan); Nakatani, Nobutake [Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521 (Japan); Department of Environmental and Symbiotic Sciences, Rakuno Gakuen University, 582 Bunkyodai-Midorimachi, Ebetsu, Hokkaido 069-8501 (Japan); Sakugawa, Hiroshi [Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521 (Japan)

    2014-09-15

    We studied the spatial distributions of and the diurnal variations in four low molecular weight (LMW) carbonyl compounds, formaldehyde, acetaldehyde, propionaldehyde, and glyoxal, in coastal seawater. The samples were taken from the coastal areas of Hiroshima Bay, the Iyo Nada, and the Bungo Channel, western Japan. The formaldehyde, acetaldehyde, and glyoxal concentrations were higher in the northern part of Hiroshima Bay than at offshore sampling points in the Iyo Nada and the Bungo Channel. These three compounds were found at much higher concentrations in the surface water than in deeper water layers in Hiroshima Bay. It is noteworthy that propionaldehyde was not detected in any of the seawater samples, the concentrations present being lower than the detection limit (1 nanomole per liter (nM)) of the high performance liquid chromatography (HPLC) system we used. Photochemical and biological experiments were performed in the laboratory to help understand the characteristic distributions and fates of the LMW carbonyl compounds. The primary process controlling their fate in the coastal environment appears to be their biological consumption. The direct photo degradation of propionaldehyde, initiated by ultraviolet (UV) absorption, was observed, although formaldehyde and acetaldehyde were not degraded by UV irradiation. Our results suggest that the degradation of the LMW carbonyl compounds by photochemically formed hydroxyl radicals is relatively insignificant in the study area. Atmospheric deposition is a possible source of soluble carbonyl compounds in coastal surface seawater, but it may not influence the carbonyl concentrations in offshore waters. - Highlights: • Low molecular weight (LMW) carbonyl compounds in coastal seawater were determined. • Photochemical productions of LMW carbonyl compounds in seawater were observed. • LMW carbonyl compounds were largely consumed biologically. • Photochemical degradation was relatively insignificant in the study area.

  1. Response to arsenate treatment in Schizosaccharomyces pombe and the role of its arsenate reductase activity.

    Directory of Open Access Journals (Sweden)

    Alejandro Salgado

    Full Text Available Arsenic toxicity has been studied for a long time due to its effects in humans. Although epidemiological studies have demonstrated multiple effects in human physiology, there are many open questions about the cellular targets and the mechanisms of response to arsenic. Using the fission yeast Schizosaccharomyces pombe as model system, we have been able to demonstrate a strong activation of the MAPK Spc1/Sty1 in response to arsenate. This activation is dependent on Wis1 activation and Pyp2 phosphatase inactivation. Using arsenic speciation analysis we have also demonstrated the previously unknown capacity of S. pombe cells to reduce As (V to As (III. Genetic analysis of several fission yeast mutants point towards the cell cycle phosphatase Cdc25 as a possible candidate to carry out this arsenate reductase activity. We propose that arsenate reduction and intracellular accumulation of arsenite are the key mechanisms of arsenate tolerance in fission yeast.

  2. The potential behavioral and economic impacts of widespread HMG-CoA reductase inhibitor (statin) use.

    Science.gov (United States)

    Gendle, Mathew H

    2016-12-01

    Dyslipidemia is a common pathology throughout the industrialized world, and HMG-CoA reductase inhibitors (statins) are often administered to treat elevated lipid levels. Substantial concern has been raised regarding the aggressive clinical lowering of cholesterol, particularly in light of a growing body of research linking low circulating lipid levels with negative behavioral outcomes in both human samples and non-human primate models. In 2009, Goldstein and colleagues tentatively speculated that the greed, impulsiveness, and lack of foresight that lead to the worldwide economic collapse in 2007-2008 could have been caused (in part) by depressed population cholesterol levels resulting from the widespread use of statins by workers in the financial services industry. This paper reviews the literature that links low circulating lipid levels with neurobehavioral dysfunction, develops Goldstein and colleagues' initial speculation into a formal hypothesis, and proposes several specific studies that could rigorously empirically evaluate this hypothesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Carbonyl emissions from heavy-duty diesel vehicle exhaust in China and the contribution to ozone formation potential.

    Science.gov (United States)

    Dong, Dong; Shao, Min; Li, Yue; Lu, Sihua; Wang, Yanjun; Ji, Zhe; Tang, Dagang

    2014-01-01

    Fifteen heavy-duty diesel vehicles were tested on chassis dynamometer by using typical heavy duty driving cycle and fuel economy cycle. The air from the exhaust was sampled by 2,4-dinitrophenyhydrazine cartridge and 23 carbonyl compounds were analyzed by high performance liquid chromatography. The average emission factor of carbonyls was 97.2 mg/km, higher than that of light-duty diesel vehicles and gasoline-powered vehicles. Formaldehyde, acetaldehyde, acetone and propionaldehyde were the species with the highest emission factors. Main influencing factors for carbonyl emissions were vehicle type, average speed and regulated emission standard, and the impact of vehicle loading was not evident in this study. National emission of carbonyls from diesel vehicles exhaust was calculated for China, 2011, based on both vehicle miles traveled and fuel consumption. Carbonyl emission of diesel vehicle was estimated to be 45.8 Gg, and was comparable to gasoline-powered vehicles (58.4 Gg). The emissions of formaldehyde, acetaldehyde and acetone were 12.6, 6.9, 3.8 Gg, respectively. The ozone formation potential of carbonyls from diesel vehicles exhaust was 537 mg O3/km, higher than 497 mg O3/km of none-methane hydrocarbons emitted from diesel vehicles.

  4. NCB5OR Is a Novel Soluble NAD(P)H Reductase Localized in the Endoplasmic Reticulum*S

    OpenAIRE

    Zhu, Hao; Larade, Kevin; Jackson, Timothy A.; Xie, Jianxin; Ladoux, Annie; Acker, Helmut; Berchner-Pfannschmidt, Utta; Fandrey, Joachim; Cross, Andrew R.; Lukat-Rodgers, Gudrun S.; Rodgers, Kenton R.; Bunn, H. Franklin

    2004-01-01

    The NAD(P)H cytochrome b5 oxidoreductase, Ncb5or (previously named b5+b5R), is widely expressed in human tissues and broadly distributed among the animal kingdom. NCB5OR is the first example of an animal flavohemoprotein containing cytochrome b5 and cytochrome b5 reductase domains. We initially reported human NCB5OR to be a 487-residue soluble protein that reduces cytochrome c, methemoglobin, ferricyanide, and molecular oxygen in vitro. Bioinformatic analysis of genomic sequences suggested th...

  5. Metabolic derangement of methionine and folate metabolism in mice deficient in methionine synthase reductase

    Science.gov (United States)

    Elmore, C. Lee; Wu, Xuchu; Leclerc, Daniel; Watson, Erica D.; Bottiglieri, Teodoro; Krupenko, Natalia I.; Krupenko, Sergey A.; Cross, James C.; Rozen, Rima; Gravel, Roy A.; Matthews, Rowena G.

    2007-01-01

    Hyperhomocyst(e)inemia is a metabolic derangement that is linked to the distribution of folate pools, which provide one-carbon units for biosynthesis of purines and thymidylate and for remethylation of homocysteine to form methionine. In humans, methionine synthase deficiency results in the accumulation of methyltetrahydrofolate at the expense of folate derivatives required for purine and thymidylate biosynthesis. Complete ablation of methionine synthase activity in mice results in embryonic lethality. Other mouse models for hyperhomocyst(e)inemia have normal or reduced levels of methyltetrahydrofolate and are not embryonic lethal, although they have decreased ratios of AdoMet/AdoHcy and impaired methylation. We have constructed a mouse model with a gene trap insertion in the Mtrr gene specifying methionine synthase reductase, an enzyme essential for the activity of methionine synthase. This model is a hypomorph, with reduced methionine synthase reductase activity, thus avoiding the lethality associated with the absence of methionine synthase activity. Mtrrgt/gt mice have increased plasma homocyst(e)ine, decreased plasma methionine, and increased tissue methyltetrahydrofolate. Unexpectedly, Mtrrgt/gt mice do not show decreases in the AdoMet/AdoHcy ratio in most tissues. The different metabolite profiles in the various genetic mouse models for hyperhomocysteinemia may be useful in understanding biological effects of elevated homocyst(e)ine. PMID:17369066

  6. Identification of thioredoxin glutathione reductase inhibitors that kill cestode and trematode parasites.

    Directory of Open Access Journals (Sweden)

    Fabiana Ross

    Full Text Available Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms and trematoda (flukes, while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites.

  7. New drug target in protozoan parasites: the role of thioredoxin reductase

    Directory of Open Access Journals (Sweden)

    Rosa M. Andrade

    2015-09-01

    Full Text Available Amebiasis causes approximately 70,000 deaths annually and is the third cause of death due to parasites worldwide. It is treated primarily with metronidazole, which has adverse side effects, is mutagenic and carcinogenic, and emergence of resistance is an increasing concern. Unfortunately, better therapeutic alternatives are lacking. Re-purposing of older FDA approved drugs is advantageous to drug discovery since safety and pharmacokinetic effects in humans are already known. In high throughput screening studies, we recently demonstrated that auranofin, a gold containing compound originally approved to treat rheumatoid arthritis, has activity against trophozoites of E. histolytica, the causative agent of amebiasis. Auranofin’s anti-parasitic activity is attributed to its monovalent gold molecule that readily inhibits E.histolytica thioredoxin reductase. This anti-oxidant enzyme is the only thiol-dependent flavo-reductase present in E.histolytica. Auranofin has also shown promising activity against other protozoans of significant public health importance. Altogether, this evidence suggests that auranofin has the potential to become a broad spectrum alternative therapeutic agent for diseases with a large global burden.

  8. New progesterone derivatives as inhibitors of 5alpha-reductase enzyme and prostate cancer cell growth.

    Science.gov (United States)

    Cabeza, Marisa; Bratoeff, Eugene; Heuze, Ivonne; Rojas, Arely; Terán, Nayely; Ochoa, Martha'; Ramírez-Apan, Teresa; Ramírez, Elena; Pérez, Victor; Gracia, Isabel

    2006-08-01

    In this study we report the synthesis and pharmacological evaluation, in vivo as well as in vitro, of four new progesterone derivatives 4-7. The evaluation in vivo was carried out on gonadectomized male hamsters that were injected subcutaneously daily with 1 mg/Kg of testosterone (T) and/or 1 mg/Kg of finasteride, or with 2 mg/Kg of the novel compounds. It was observed that when testosterone (T) and finasteride or compound 4 were injected together, the weight of the prostate decreased significantly as compared to that oftestosterone-treated animals. Compounds 5-7 did not show any in vivo activity. The 5alpha-reductase inhibitory activity of the novel compounds was determined in vitro using human prostate homogenates; the steroids 4-7 inhibited the 5alpha-reductase activity with IC50 values lower than that for the reference compound finasteride. 3. The effect of compounds 4-7 on the growth of lymphocytes and prostate cancer culture cells line was that steroid 4 inhibited the growth of both cells lines at a concentration of 50 microM and showed a cytotoxic effect whereas compounds 5-7 showed a much lower inhibition. Nevertheless steroids 4-7 didn't exhibit any toxic effects in vivo since the animals remained alive during the six days of treatment.

  9. Cloning and expression of koala (Phascolarctos cinereus) liver cytochrome P450 reductase.

    Science.gov (United States)

    Kong, Sandra; Ngo, Suong N T; McKinnon, Ross A; Stupans, Ieva

    2009-07-01

    The cloning, expression and characterization of hepatic NADPH-cytochrome P450 reductase (CPR) from koala (Phascolarctos cinereus) is described. Two 2059 bp koala liver CPR cDNAs, designated CPR1 and CPR2, were cloned by reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends. The koala CPR cDNAs encode proteins of 678 amino acids and share 85% amino acid sequence identity to human CPR. Transfection of the koala CPR cDNAs into Cos-7 cells resulted in the expression of proteins, which were recognized by a goat-antihuman CPR antibody. The koala CPR1 and 2 cDNA-expressed enzymes catalysed cytochrome c reductase at the rates of 4.9 +/- 0.5 and 2.6 +/- 0.4 nmol/min/mg protein (mean +/- SD, n = 3), respectively which were comparable to that of rat CPR cDNA-expressed enzyme. The apparent Km value for CPR activity in koala liver microsomes was 11.61 +/- 6.01 microM, which is consistent with that reported for rat CPR enzyme. Northern analysis detected a CPR mRNA band of approximately 2.6 kb. Southern analysis suggested a single PCR gene across species. The present study provides primary molecular data regarding koala CPR1 and CPR2 genes in this unique marsupial species.

  10. Genes encoding chimeras of Neurospora crassa erg-3 and human ...

    Indian Academy of Sciences (India)

    http://www.ias.ac.in/article/fulltext/jbsc/027/02/0105-0112. Keywords. Lamin B receptor; sterol reductase. Abstract. The human gene TM7SF2 encodes a polypeptide (SR-1) with high sequence similarity to sterol C-14 reductase, a key sterol biosynthetic enzyme in fungi, plants and mammals. In Neurospora and yeast this ...

  11. Aldose reductase inhibition prevents metaplasia of airway epithelial cells.

    Directory of Open Access Journals (Sweden)

    Umesh C S Yadav

    Full Text Available BACKGROUND: Goblet cell metaplasia that causes mucus hypersecretion and obstruction in the airway lumen could be life threatening in asthma and chronic obstructive pulmonary disease patients. Inflammatory cytokines such as IL-13 mediate the transformation of airway ciliary epithelial cells to mucin-secreting goblet cells in acute as well as chronic airway inflammatory diseases. However, no effective and specific pharmacologic treatment is currently available. Here, we investigated the mechanisms by which aldose reductase (AR regulates the mucus cell metaplasia in vitro and in vivo. METHODOLOGY/FINDINGS: Metaplasia in primary human small airway epithelial cells (SAEC was induced by a Th2 cytokine, IL-13, without or with AR inhibitor, fidarestat. After 48 h of incubation with IL-13 a large number of SAEC were transformed into goblet cells as determined by periodic acid-schiff (PAS-staining and immunohistochemistry using antibodies against Mucin5AC. Further, IL-13 significantly increased the expression of Mucin5AC at mRNA and protein levels. These changes were significantly prevented by treatment of the SAEC with AR inhibitor. AR inhibition also decreased IL-13-induced expression of Muc5AC, Muc5B, and SPDEF, and phosphorylation of JAK-1, ERK1/2 and STAT-6. In a mouse model of ragweed pollen extract (RWE-induced allergic asthma treatment with fidarestat prevented the expression of IL-13, phosphorylation of STAT-6 and transformation of epithelial cells to goblet cells in the lung. Additionally, while the AR-null mice were resistant, wild-type mice showed goblet cell metaplasia after challenge with RWE. CONCLUSIONS: The results show that exposure of SAEC to IL-13 caused goblet cell metaplasia, which was significantly prevented by AR inhibition. Administration of fidarestat to mice prevented RWE-induced goblet cell metaplasia and AR null mice were largely resistant to allergen induced changes in the lung. Thus our results indicate that AR inhibitors

  12. Aldose reductase inhibition prevents metaplasia of airway epithelial cells.

    Science.gov (United States)

    Yadav, Umesh C S; Aguilera-Aguirre, Leopoldo; Ramana, Kota V; Boldogh, Istvan; Srivastava, Satish K

    2010-12-28

    Goblet cell metaplasia that causes mucus hypersecretion and obstruction in the airway lumen could be life threatening in asthma and chronic obstructive pulmonary disease patients. Inflammatory cytokines such as IL-13 mediate the transformation of airway ciliary epithelial cells to mucin-secreting goblet cells in acute as well as chronic airway inflammatory diseases. However, no effective and specific pharmacologic treatment is currently available. Here, we investigated the mechanisms by which aldose reductase (AR) regulates the mucus cell metaplasia in vitro and in vivo. Metaplasia in primary human small airway epithelial cells (SAEC) was induced by a Th2 cytokine, IL-13, without or with AR inhibitor, fidarestat. After 48 h of incubation with IL-13 a large number of SAEC were transformed into goblet cells as determined by periodic acid-schiff (PAS)-staining and immunohistochemistry using antibodies against Mucin5AC. Further, IL-13 significantly increased the expression of Mucin5AC at mRNA and protein levels. These changes were significantly prevented by treatment of the SAEC with AR inhibitor. AR inhibition also decreased IL-13-induced expression of Muc5AC, Muc5B, and SPDEF, and phosphorylation of JAK-1, ERK1/2 and STAT-6. In a mouse model of ragweed pollen extract (RWE)-induced allergic asthma treatment with fidarestat prevented the expression of IL-13, phosphorylation of STAT-6 and transformation of epithelial cells to goblet cells in the lung. Additionally, while the AR-null mice were resistant, wild-type mice showed goblet cell metaplasia after challenge with RWE. The results show that exposure of SAEC to IL-13 caused goblet cell metaplasia, which was significantly prevented by AR inhibition. Administration of fidarestat to mice prevented RWE-induced goblet cell metaplasia and AR null mice were largely resistant to allergen induced changes in the lung. Thus our results indicate that AR inhibitors such as fidarestat could be developed as therapeutic agents to

  13. Steroidal antiandrogens and 5alpha-reductase inhibitors.

    Science.gov (United States)

    Bratoeff, E; Ramírez, E; Murillo, E; Flores, G; Cabeza, M

    1999-12-01

    The purpose of this work is to synthesize a pregnane derivative with a high antiandrogenic effect or a high inhibitory activity for the enzyme 5 alpha-reductase type 2. Benign prostatic hyperplasia and prostate cancer are androgen dependent diseases which afflict a large percentage of the male population. Dihydrotestosterone 3, a 5 alpha-reductase metabolite of testosterone 2 has been implicated as a causative factor in the progression of these diseases, largely through the clinical evaluation of males who are genetically deficient of steroid 5 alpha-reductase enzyme. As a result of this study, the inhibition of this enzyme has become a pharmacological strategy for the design and synthesis of new drugs. The advent of finasteride 22 "figure 5" a 5 alpha-reductase inhibitor, has greatly alleviated the symptoms associated with benign prostatic hyperplasia. On the other hand, the discovery of cyproterone acetate 4 "figure 2" alone or in combination with the antiandrogens flutamide 14 "figure 3" or bicalutamide 21 has greatly reduced the misery of prostate cancer. Prostate cancer kills about 40,000 men in the USA and approximately 400,000 prostatectomies are performed each year. In our laboratory we have recently synthesized ten new progesterone derivatives 17 alpha-acyloyloxy-6-halo (chloro, bromo) 16 beta-methyl-4, 6-pregnadiene-3, 20-diones (54a-54e and 55a-55e), "figure 10". These steroids were evaluated as antiandrogens and exhibited a much higher activity than the commercially available cyproterone acetate 4. The same compounds were also evaluated as 5 alpha-reductase inhibitors and showed a slightly higher inhibitory activity than that of finasteride 22, the drug of choice today for the treatment of benign prostatic hyperplasia In another study we synthesized several new 4-halo (bromo and chloro) 17 alpha-benzoyloxy and also 4-halo-17 alpha-acetoxy progesterone derivatives (58-63) "figure 13". These compounds were prepared from the commercially available 17 alpha

  14. In silico identification of catalytic residues in azobenzene reductase from Bacillus subtilis and its docking studies with azo dyes.

    Science.gov (United States)

    Ramanathan, K; Shanthi, V; Sethumadhavan, Rao

    2009-12-01

    Prediction of catalytic residues of an enzyme molecule is of great importance for a range of applications including molecular docking, drug design, structural identification and comparison of binding sites. Over the last decades, many studies have been conducted to identify the enzyme catalytic site. But, the catalytic residues of the azobenzene reductase from bacillus subtilis are still unknown. Investigation shows that under anaerobic conditions, azo dyes can be reduced by this enzyme and other environmental microorganisms to colorless amines, which may be toxic, mutagenic, and carcinogenic to humans and animals. To assess and estimate the toxicity, it is essential to identify the catalytic residues of this enzyme. The computational methods developed that address this issue are few. In this approach, we identify the catalytic residues of azobenzene reductase from bacillus subtilis, which were then analyzed in terms of properties including function, conservation, hydrogen bonding, B-factor, solvent accessibility, and flexibility. The results indicate that, Lys (83) and Tyr (74) play an important role as catalytic site residues in the azobenzene reductase from bacillus subtilis. It is hoped that this information will provide a better understanding of the molecular mechanisms involved in catalysis and a heuristic basis for predicting the catalytic residues in enzymes of unknown function. In this study, our approach mainly looks for a better understanding of the biodegradation of the Sudan I, Sudan II, Sudan III and Sudan IV dyes mediated by azobenzene reductase from bacillus subtilis. Further more, the catalytic site residues information is essential for understanding and altering substrate specificity and for the design of enzyme inhibitors.

  15. Antimicrobial activity and physical characterization of silver nanoparticles green synthesized using nitrate reductase from Fusarium oxysporum.

    Science.gov (United States)

    Gholami-Shabani, Mohammadhassan; Akbarzadeh, Azim; Norouzian, Dariush; Amini, Abdolhossein; Gholami-Shabani, Zeynab; Imani, Afshin; Chiani, Mohsen; Riazi, Gholamhossein; Shams-Ghahfarokhi, Masoomeh; Razzaghi-Abyaneh, Mehdi

    2014-04-01

    Nanostructures from natural sources have received major attention due to wide array of biological activities and less toxicity for humans, animals, and the environment. In the present study, silver nanoparticles were successfully synthesized using a fungal nitrate reductase, and their biological activity was assessed against human pathogenic fungi and bacteria. The enzyme was isolated from Fusarium oxysporum IRAN 31C after culturing on malt extract-glucose-yeast extract-peptone (MGYP) medium. The enzyme was purified by a combination of ultrafiltration and ion exchange chromatography on DEAE Sephadex and its molecular weight was estimated by gel filtration on Sephacryl S-300. The purified enzyme had a maximum yield of 50.84 % with a final purification of 70 folds. With a molecular weight of 214 KDa, it is composed of three subunits of 125, 60, and 25 KDa. The purified enzyme was successfully used for synthesis of silver nanoparticles in a way dependent upon NADPH using gelatin as a capping agent. The synthesized silver nanoparticles were characterized by X-ray diffraction, dynamic light scattering spectroscopy, and transmission and scanning electron microscopy. These stable nonaggregating nanoparticles were spherical in shape with an average size of 50 nm and a zeta potential of -34.3. Evaluation of the antimicrobial effects of synthesized nanoparticles by disk diffusion method showed strong growth inhibitory activity against all tested human pathogenic fungi and bacteria as evident from inhibition zones that ranged from 14 to 25 mm. Successful green synthesis of biologically active silver nanoparticles by a nitrate reductase from F. oxysporum in the present work not only reduces laborious downstream steps such as purification of nanoparticle from interfering cellular components, but also provides a constant source of safe biologically-active nanomaterials with potential application in agriculture and medicine.

  16. Resveratrol up-regulates the erythrocyte plasma membrane redox system and mitigates oxidation-induced alterations in erythrocytes during aging in humans.

    Science.gov (United States)

    Pandey, Kanti Bhooshan; Rizvi, Syed Ibrahim

    2013-06-01

    Reactive oxygen/nitrogen species (ROS/RNS)-mediated oxidative damage followed by disturbed cellular homeostasis is involved in aging and related consequences. Lipid peroxidation, post-translational modifications of proteins, and an impaired defense system due to increased oxidative stress jeopardize cell fate and functions, resulting in cell senescence. Resveratrol, a natural stilbene, has extensively been reported to elicit a plethora of health-promoting effects. The present study carried out on 97 healthy human subjects (62 males and 35 females) of both sexes provides experimental evidence that resveratrol confers ability to up-regulate the plasma membrane redox system (PMRS) along with ascorbate free radical reductase, a compensatory system operating in the cell to maintain cellular redox state. Furthermore, resveratrol provided significant protection against lipid peroxidation and protein carbonylation and restored the cellular redox homeostasis measured in terms of glutathione (GSH) and sulfhydryl (-SH) group levels during oxidation injury in erythrocytes of different age groups in humans. Findings suggest a possible role of resveratrol in retardation of age-dependent oxidative stress.

  17. Recent structural insights into the function of copper nitrite reductases.

    Science.gov (United States)

    Horrell, Sam; Kekilli, Demet; Strange, Richard W; Hough, Michael A

    2017-11-15

    Copper nitrite reductases (CuNiR) carry out the first committed step of the denitrification pathway of the global nitrogen cycle, the reduction of nitrite (NO 2 - ) to nitric oxide (NO). As such, they are of major agronomic and environmental importance. CuNiRs occur primarily in denitrifying soil bacteria which carry out the overall reduction of nitrate to dinitrogen. In this article, we review the insights gained into copper nitrite reductase (CuNiR) function from three dimensional structures. We particularly focus on developments over the last decade, including insights from serial femtosecond crystallography using X-ray free electron lasers (XFELs) and from the recently discovered 3-domain CuNiRs.

  18. Hydroxyurea-Mediated Cytotoxicity Without Inhibition of Ribonucleotide Reductase

    Directory of Open Access Journals (Sweden)

    Li Phing Liew

    2016-11-01

    Full Text Available In many organisms, hydroxyurea (HU inhibits class I ribonucleotide reductase, leading to lowered cellular pools of deoxyribonucleoside triphosphates. The reduced levels for DNA precursors is believed to cause replication fork stalling. Upon treatment of the hyperthermophilic archaeon Sulfolobus solfataricus with HU, we observe dose-dependent cell cycle arrest, accumulation of DNA double-strand breaks, stalled replication forks, and elevated levels of recombination structures. However, Sulfolobus has a HU-insensitive class II ribonucleotide reductase, and we reveal that HU treatment does not significantly impact cellular DNA precursor pools. Profiling of protein and transcript levels reveals modulation of a specific subset of replication initiation and cell division genes. Notably, the selective loss of the regulatory subunit of the primase correlates with cessation of replication initiation and stalling of replication forks. Furthermore, we find evidence for a detoxification response induced by HU treatment.

  19. Differential expression of disulfide reductase enzymes in a free-living platyhelminth (Dugesia dorotocephala.

    Directory of Open Access Journals (Sweden)

    Alberto Guevara-Flores

    Full Text Available A search of the disulfide reductase activities expressed in the adult stage of the free-living platyhelminth Dugesia dorotocephala was carried out. Using GSSG or DTNB as substrates, it was possible to obtain a purified fraction containing both GSSG and DTNB reductase activities. Through the purification procedure, both disulfide reductase activities were obtained in the same chromatographic peak. By mass spectrometry analysis of peptide fragments obtained after tryptic digestion of the purified fraction, the presence of glutathione reductase (GR, thioredoxin-glutathione reductase (TGR, and a putative thioredoxin reductase (TrxR was detected. Using the gold compound auranofin to selectively inhibit the GSSG reductase activity of TGR, it was found that barely 5% of the total GR activity in the D. dorotocephala extract can be assigned to GR. Such strategy did allow us to determine the kinetic parameters for both GR and TGR. Although It was not possible to discriminate DTNB reductase activity due to TrxR from that of TGR, a chromatofocusing experiment with a D. dorotocephala extract resulted in the obtention of a minor protein fraction enriched in TrxR, strongly suggesting its presence as a functional protein. Thus, unlike its parasitic counterparts, in the free-living platyhelminth lineage the three disulfide reductases are present as functional proteins, albeit TGR is still the major disulfide reductase involved in the reduction of both Trx and GSSG. This fact suggests the development of TGR in parasitic flatworms was not linked to a parasitic mode of life.

  20. Deep-blue phosphorescence from perfluoro carbonyl-substituted iridium complexes.

    Science.gov (United States)

    Lee, Sunghun; Kim, Seul-Ong; Shin, Hyun; Yun, Hui-Jun; Yang, Kiyull; Kwon, Soon-Ki; Kim, Jang-Joo; Kim, Yun-Hi

    2013-09-25

    The new deep-blue iridium(III) complexes, (TF)2Ir(pic), (TF)2Ir(fptz), (HF)2Ir(pic), and (HF)2Ir(fptz), consisting of 2',4″-difluororphenyl-3-methylpyridine with trifluoromethyl carbonyl or heptafluoropropyl carbonyl at the 3' position as the main ligand and a picolinate or a trifluoromethylated-triazole as the ancillary ligand, were synthesized and characterized for applications in organic light-emitting diodes (OLEDs). Density function theory (DFT) calculations showed that these iridium complexes had a wide band gap, owing to the introduction of the strong electron withdrawing perfluoro carbonyl group. Time-dependent DFT (TD-DFT) calculations suggested that their lowest triplet excited state was dominated by a HOMO → LUMO transition and that the contribution of the metal-to-ligand charge transfer (MLCT) was higher than 34% for all four complexes, indicating that strong spin-orbit coupling exists in the complexes. The 10 wt % (TF)2Ir(pic) doped 9-(3-(9H-carbazole-9-yl)phenyl)-3-(dibromophenylphosphoryl)-9H-carbazole (mCPPO1) film exhibited the highest photoluminescence quantum yield of 74 ± 3% among the films based on the four complexes. Phosphorescent OLEDs based on (TF)2Ir(pic) and (TF)2Ir(fptz) exhibited maximum external quantum efficiencies of 17.1% and 8.4% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.141, 0.158) and (0.147, 0.116), respectively. These CIE coordinates represent some of the deepest blue emissions ever achieved from phosphorescent OLEDs with considerably high EQEs.

  1. Intraethnic variation in steroid-5-alpha-reductase polymorphisms in ...

    Indian Academy of Sciences (India)

    in prostate cancer patients: a potential factor implicated in. 5-alpha-reductase inhibitor treatment. Luis Alberto Henríquez-Hernández, Almudena Valenciano, Palmira Foro-Arnalot, María Jesús Álvarez-Cubero,. José Manuel Cozar, José Francisco Suárez-Novo, Manel Castells-Esteve, Pablo Fernández-Gonzalo,.

  2. Long term treatment with betaine in methylenetetrahydrofolate reductase deficiency.

    OpenAIRE

    Ronge, E; Kjellman, B

    1996-01-01

    A girl aged 7.5 years with deficiency of 5,10-methylenetetrahydrofolate reductase was treated from early infancy with betaine, 3-6 g daily. She has slight microcephaly, moderate developmental delay, and impaired vision but there have been no obvious signs of folate deficiency. From 4 years of age, she developed an unexplained extreme increase in appetite and weight. Recent magnetic resonance imaging of her brain was normal. The plasma methionine levels have been normal but in the lower range,...

  3. Determination of carbonyl compounds in air by HPLC; Determinacion de compuestos carbonilicos en aire por HPLC

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, S.; Perez, R.M.; Campos, A.; Gonzalez, D.

    1995-07-01

    A method for the determination of seven carbonyl compounds in air is presented. The procedure involve sampling of air by a Sep-Pak Cartridge impregnated with 2,4-dinitrophenylhydrazine. Elution was done with 3 mL of acetonitrile and the eluate was diluted to 5 mL. The analysis was done by HPLC with UV detection and external standard method quantification. It has been achieved relative standard deviations about 5% and detection limits of 80 ng/cartridge for formaldehyde, acetaldehyde and acetoacetonitrile. Three different types of samples (rural, urban, petrol emission) were successfully analyzed. (Author) 12 refs.

  4. Non-enzymatic modification of aminophospholipids by carbonyl-amine reactions.

    Science.gov (United States)

    Naudí, Alba; Jové, Mariona; Ayala, Victòria; Cabré, Rosanna; Portero-Otín, Manuel; Pamplona, Reinald

    2013-02-05

    Non-enzymatic modification of aminophospholipids by lipid peroxidation-derived aldehydes and reducing sugars through carbonyl-amine reactions are thought to contribute to the age-related deterioration of cellular membranes and to the pathogenesis of diabetic complications. Much evidence demonstrates the modification of aminophospholipids by glycation, glycoxidation and lipoxidation reactions. Therefore, a number of early and advanced Maillard reaction-lipid products have been detected and quantified in different biological membranes. These modifications may be accumulated during aging and diabetes, introducing changes in cell membrane physico-chemical and biological properties.

  5. A Device-Independent Evaluation of Carbonyl Emissions from Heated Electronic Cigarette Solvents.

    Directory of Open Access Journals (Sweden)

    Ping Wang

    Full Text Available To investigate how the two main electronic (e- cigarette solvents-propylene glycol (PG and glycerol (GL-modulate the formation of toxic volatile carbonyl compounds under precisely controlled temperatures in the absence of nicotine and flavor additives.PG, GL, PG:GL = 1:1 (wt/wt mixture, and two commercial e-cigarette liquids were vaporized in a stainless steel, tubular reactor in flowing air ranging up to 318°C to simulate e-cigarette vaping. Aerosols were collected and analyzed to quantify the amount of volatile carbonyls produced with each of the five e-liquids.Significant amounts of formaldehyde and acetaldehyde were detected at reactor temperatures ≥215°C for both PG and GL. Acrolein was observed only in e-liquids containing GL when reactor temperatures exceeded 270°C. At 318°C, 2.03±0.80 μg of formaldehyde, 2.35±0.87 μg of acetaldehyde, and a trace amount of acetone were generated per milligram of PG; at the same temperature, 21.1±3.80 μg of formaldehyde, 2.40±0.99 μg of acetaldehyde, and 0.80±0.50 μg of acrolein were detected per milligram of GL.We developed a device-independent test method to investigate carbonyl emissions from different e-cigarette liquids under precisely controlled temperatures. PG and GL were identified to be the main sources of toxic carbonyl compounds from e-cigarette use. GL produced much more formaldehyde than PG. Besides formaldehyde and acetaldehyde, measurable amounts of acrolein were also detected at ≥270°C but only when GL was present in the e-liquid. At 215°C, the estimated daily exposure to formaldehyde from e-cigarettes, exceeded United States Environmental Protection Agency (USEPA and California Office of Environmental Health Hazard Assessment (OEHHA acceptable limits, which emphasized the need to further examine the potential cancer and non-cancer health risks associated with e-cigarette use.

  6. Mechanistic Investigations of the Iron(III)-Catalyzed Carbonyl-Olefin Metathesis Reaction.

    Science.gov (United States)

    Ludwig, Jacob R; Phan, Susan; McAtee, Christopher C; Zimmerman, Paul M; Devery, James J; Schindler, Corinna S

    2017-08-09

    Iron(III)-catalyzed carbonyl-olefin ring-closing metathesis represents a new approach toward the assembly of molecules traditionally generated by olefin-olefin metathesis or olefination. Herein, we report detailed synthetic, spectroscopic, kinetic, and computational studies to determine the mechanistic features imparted by iron(III), substrate, and temperature to the catalytic cycle. These data are consistent with an iron(III)-mediated asynchronous, concerted [2+2]-cycloaddition to form an intermediate oxetane as the turnover-limiting step. Fragmentation of the oxetane via Lewis acid-activation results in the formation of five- and six-membered unsaturated carbocycles.

  7. A green synthesis of α,β-unsaturated carbonyl compounds from glyceraldehyde acetonide

    Directory of Open Access Journals (Sweden)

    Cláudia O. Veloso

    2011-01-01

    Full Text Available The catalytic behavior of Cs-exchanged and Cs-impregnated zeolites (X and Y was studied using the Knoevenagel condensation between glyceraldehyde acetonide and ethyl acetoacetate in order to produce the corresponding α,β-unsaturated carbonyl compound that is an important intermediate for fine chemicals. The influence of reaction temperature, type of zeolite, and basicity of the sites on the catalytic behavior of the samples was evaluated. All zeolites were active for the studied reaction. The formation of the main condensation product was favored at lower reaction temperatures. Products of further condensations were also observed especially for samples that were only dried before catalytic test.

  8. Non-Enzymatic Modification of Aminophospholipids by Carbonyl-Amine Reactions

    Directory of Open Access Journals (Sweden)

    Reinald Pamplona

    2013-02-01

    Full Text Available Non-enzymatic modification of aminophospholipids by lipid peroxidation-derived aldehydes and reducing sugars through carbonyl-amine reactions are thought to contribute to the age-related deterioration of cellular membranes and to the pathogenesis of diabetic complications. Much evidence demonstrates the modification of aminophospholipids by glycation, glycoxidation and lipoxidation reactions. Therefore, a number of early and advanced Maillard reaction-lipid products have been detected and quantified in different biological membranes. These modifications may be accumulated during aging and diabetes, introducing changes in cell membrane physico-chemical and biological properties.

  9. Multiband microwave absorption films based on defective multiwalled carbon nanotubes added carbonyl iron/acrylic resin

    Energy Technology Data Exchange (ETDEWEB)

    Li Yong, E-mail: liyong1897@163.co [Institute of Naval Logistic Technology and Equipment of PLA, Beijing 100072 (China); Chen Changxin, E-mail: chen.c.x@sjtu.edu.c [National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Pan Xiaoyan [School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Ni Yuwei; Zhang Song; Huang, Jie [Institute of Naval Logistic Technology and Equipment of PLA, Beijing 100072 (China); Chen Da; Zhang Yafei [National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of the Ministry of Education, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2009-05-01

    Defective multiwalled carbon nanotubes (MWCNTs) were introduced to the carbonyl iron (CI) based composites to improve its microwave absorption by a simple ultrasonic mixing process. The electromagnetic parameters were measured in the 2-18 GHz range. Microwave absorption of CI based composites with 2 mm in thickness was evidently enhanced by adding as little as 1.0 wt% defective MWCNTs with two well separated absorption peaks exceeding -20 dB, as compared with that of pure CI based and defective MWCNTs composites. The enhancement mechanism is thought due to the interaction and better electromagnetic match between defective MWCNTs and ferromagnetic CI particles.

  10. Sensitivity of Saccharomyces cerevisiae defective in TOR signaling pathway to carbonyl/oxidative stress

    Directory of Open Access Journals (Sweden)

    Valishkevych B. V.

    2014-09-01

    Full Text Available Aim. To investigate the influence of carbonyl/oxidative stress induced by glyoxal, methylglyoxal and hydrogen peroxide on the survival of Saccharomyces cerevisiae, defective for different parts of TOR- signaling pathway, grown on glucose or fructose. Methods. The assessment of number of colony-forming units to determine the yeast reproductive ability. Results. It was shown that at certain concentrations the mentioned above toxicants caused an increase in yeast survival, indicating the hormetic effect. Conclusions. The TOR signaling pathway is involved in the hormetic effect, but it is specific for each strain and depends on the type of carbohydrate in the incubation medium.

  11. Synthesis of [[sup 14]C]-N-[(trimethylamineboryl)carbonyl]-phenylalanine-methyl ester

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.C. III; Wyrick, S.D.; Hall, I.H. (North Carolina Univ., Chapel Hill, NC (United States). School of Pharmacy); Sood, A.; Spielvogel, B.F. (Boron Biologicals Inc., Raleigh, NC (United States))

    1992-08-01

    Reported is the synthesis of [[sup 14]C]-L-N-[(trimethylamine-boryl) carbonyl]-phenylalanine methyl ester, a boron containing [alpha]-amino acid dipeptide analog with antineoplastic, anti-inflammatory, and hypolipidemic activities. The [sup 14]C label is universally distributed among all carbon positions of the phenylalanine portion of the molecule. Briefly, the dipeptide is prepared by reacting the phenylalanine methyl ester hydrochloride salt with trimethylamine-carboxyborane, triphenylphospine (TPP), CCl[sub 4], and triethylamine (TEA) in acetonitrile, for 24 hours. The final product afforded a specific activity of 5.71 mCi/mmol. (author).

  12. Carbon-deuterium bonds as probes of dihydrofolate reductase.

    Science.gov (United States)

    Thielges, Megan C; Case, David A; Romesberg, Floyd E

    2008-05-21

    Much effort has been directed toward understanding the contributions of electrostatics and dynamics to protein function and especially to enzyme catalysis. Unfortunately, these studies have been limited by the absence of direct experimental probes. We have been developing the use of carbon-deuterium bonds as probes of proteins and now report the application of the technique to the enzyme dihydrofolate reductase, which catalyzes a hydride transfer and has served as a paradigm for biological catalysis. We observe that the stretching absorption frequency of (methyl- d 3) methionine carbon-deuterium bonds shows an approximately linear dependence on solvent dielectric. Solvent and computational studies support the empirical interpretation of the stretching frequency in terms of local polarity. To begin to explore the use of this technique to study enzyme function and mechanism, we report a preliminary analysis of (methyl- d 3) methionine residues within dihydrofolate reductase. Specifically, we characterize the IR absorptions at Met16 and Met20, within the catalytically important Met20 loop, and Met42, which is located within the hydrophobic core of the enzyme. The results confirm the sensitivity of the carbon-deuterium bonds to their local protein environment, demonstrate that dihydrofolate reductase is electrostatically and dynamically heterogeneous, and lay the foundation for the direct characterization protein electrostatics and dynamics and, potentially, their contribution to catalysis.

  13. DIHYDROFOLATE REDUCTASE AS A VERSATILE DRUG TARGET IN HEALTHCARE

    Directory of Open Access Journals (Sweden)

    Naira Rashid

    2016-09-01

    Full Text Available Dihydrofolate reductase is one of the important enzymes for thymidylate and purine synthesis. It has been used as a drug target for treatment of various diseases. A large number of pharmaceutical drugs have been designed to inhibit the activity of dihydrofolate reductase. However, over the period of time some organisms have developed resistance against some of these drugs. There is also a chance of cross reactivity for these drugs, as they may target the dihydrofolate reductase enzyme of other organisms. Although using NMR spectroscopy, phylogenetic sequence analysis, comparative sequence analysis between dihydrofolate enzymes of various organisms and molecular modeling studies, a lot has been unraveled about the difference in the structure of this enzyme in various organisms, yet there is a need for deeper understanding of these differences so as to design drugs that are specific to their targets and reduce the chance for cross reactivity. The dihydrofolate enzyme can also be explored for treatment of various other diseases that are associated with the folate cycle.

  14. Catalase as a sulfide-sulfur oxido-reductase: An ancient (and modern? regulator of reactive sulfur species (RSS

    Directory of Open Access Journals (Sweden)

    Kenneth R. Olson

    2017-08-01

    Full Text Available Catalase is well-known as an antioxidant dismutating H2O2 to O2 and H2O. However, catalases evolved when metabolism was largely sulfur-based, long before O2 and reactive oxygen species (ROS became abundant, suggesting catalase metabolizes reactive sulfide species (RSS. Here we examine catalase metabolism of H2Sn, the sulfur analog of H2O2, hydrogen sulfide (H2S and other sulfur-bearing molecules using H2S-specific amperometric electrodes and fluorophores to measure polysulfides (H2Sn; SSP4 and ROS (dichlorofluorescein, DCF. Catalase eliminated H2Sn, but did not anaerobically generate H2S, the expected product of dismutation. Instead, catalase concentration- and oxygen-dependently metabolized H2S and in so doing acted as a sulfide oxidase with a P50 of 20 mmHg. H2O2 had little effect on catalase-mediated H2S metabolism but in the presence of the catalase inhibitor, sodium azide (Az, H2O2 rapidly and efficiently expedited H2S metabolism in both normoxia and hypoxia suggesting H2O2 is an effective electron acceptor in this reaction. Unexpectedly, catalase concentration-dependently generated H2S from dithiothreitol (DTT in both normoxia and hypoxia, concomitantly oxidizing H2S in the presence of O2. H2S production from DTT was inhibited by carbon monoxide and augmented by NADPH suggesting that catalase heme-iron is the catalytic site and that NADPH provides reducing equivalents. Catalase also generated H2S from garlic oil, diallyltrisulfide, thioredoxin and sulfur dioxide, but not from sulfite, metabisulfite, carbonyl sulfide, cysteine, cystine, glutathione or oxidized glutathione. Oxidase activity was also present in catalase from Aspergillus niger. These results show that catalase can act as either a sulfide oxidase or sulfur reductase and they suggest that these activities likely played a prominent role in sulfur metabolism during evolution and may continue do so in modern cells as well. This also appears to be the first observation of catalase

  15. Catalase as a sulfide-sulfur oxido-reductase: An ancient (and modern?) regulator of reactive sulfur species (RSS).

    Science.gov (United States)

    Olson, Kenneth R; Gao, Yan; DeLeon, Eric R; Arif, Maaz; Arif, Faihaan; Arora, Nitin; Straub, Karl D

    2017-08-01

    Catalase is well-known as an antioxidant dismutating H2O2 to O2 and H2O. However, catalases evolved when metabolism was largely sulfur-based, long before O2 and reactive oxygen species (ROS) became abundant, suggesting catalase metabolizes reactive sulfide species (RSS). Here we examine catalase metabolism of H2Sn, the sulfur analog of H2O2, hydrogen sulfide (H2S) and other sulfur-bearing molecules using H2S-specific amperometric electrodes and fluorophores to measure polysulfides (H2Sn; SSP4) and ROS (dichlorofluorescein, DCF). Catalase eliminated H2Sn, but did not anaerobically generate H2S, the expected product of dismutation. Instead, catalase concentration- and oxygen-dependently metabolized H2S and in so doing acted as a sulfide oxidase with a P50 of 20mmHg. H2O2 had little effect on catalase-mediated H2S metabolism but in the presence of the catalase inhibitor, sodium azide (Az), H2O2 rapidly and efficiently expedited H2S metabolism in both normoxia and hypoxia suggesting H2O2 is an effective electron acceptor in this reaction. Unexpectedly, catalase concentration-dependently generated H2S from dithiothreitol (DTT) in both normoxia and hypoxia, concomitantly oxidizing H2S in the presence of O2. H2S production from DTT was inhibited by carbon monoxide and augmented by NADPH suggesting that catalase heme-iron is the catalytic site and that NADPH provides reducing equivalents. Catalase also generated H2S from garlic oil, diallyltrisulfide, thioredoxin and sulfur dioxide, but not from sulfite, metabisulfite, carbonyl sulfide, cysteine, cystine, glutathione or oxidized glutathione. Oxidase activity was also present in catalase from Aspergillus niger. These results show that catalase can act as either a sulfide oxidase or sulfur reductase and they suggest that these activities likely played a prominent role in sulfur metabolism during evolution and may continue do so in modern cells as well. This also appears to be the first observation of catalase reductase

  16. Triple aldose reductase/α-glucosidase/radical scavenging high-resolution profiling combined with high-performance liquid chromatography – high-resolution mass spectrometry – solid-phase extraction – nuclear magnetic resonance spectroscopy for identification of antidiabetic constituents in crude

    DEFF Research Database (Denmark)

    Tahtah, Yousof; Kongstad, Kenneth Thermann; Wubshet, Sileshi Gizachew

    2015-01-01

    In this work, development of a new microplate-based high-resolution profiling assay using recombinant human aldose reductase is presented. Used together with high-resolution radical scavenging and high-resolution α-glucosidase assays, it provided the first report of a triple aldose reductase/α-glucosidase...... high-performance liquid chromatography – high-resolution mass spectrometry – solid-phase extraction – nuclear magnetic resonance spectroscopy. The only α-glucosidase inhibitor was baicalein, whereas main aldose reductase inhibitors in the crude extract were baicalein and skullcapflavone II, and main...

  17. Engineered Trx2p industrial yeast strain protects glycolysis and fermentation proteins from oxidative carbonylation during biomass propagation

    Directory of Open Access Journals (Sweden)

    Gómez-Pastor Rocío

    2012-01-01

    Full Text Available Abstract Background In the yeast biomass production process, protein carbonylation has severe adverse effects since it diminishes biomass yield and profitability of industrial production plants. However, this significant detriment of yeast performance can be alleviated by increasing thioredoxins levels. Thioredoxins are important antioxidant defenses implicated in many functions in cells, and their primordial functions include scavenging of reactive oxygen species that produce dramatic and irreversible alterations such as protein carbonylation. Results In this work we have found several proteins specifically protected by yeast Thioredoxin 2 (Trx2p. Bidimensional electrophoresis and carbonylated protein identification from TRX-deficient and TRX-overexpressing cells revealed that glycolysis and fermentation-related proteins are specific targets of Trx2p protection. Indeed, the TRX2 overexpressing strain presented increased activity of the central carbon metabolism enzymes. Interestingly, Trx2p specifically preserved alcohol dehydrogenase I (Adh1p from carbonylation, decreased oligomer aggregates and increased its enzymatic activity. Conclusions The identified proteins suggest that the fermentative capacity detriment observed under industrial conditions in T73 wine commercial strain results from the oxidative carbonylation of specific glycolytic and fermentation enzymes. Indeed, increased thioredoxin levels enhance the performance of key fermentation enzymes such as Adh1p, which consequently increases fermentative capacity.

  18. Engineered Trx2p industrial yeast strain protects glycolysis and fermentation proteins from oxidative carbonylation during biomass propagation.

    Science.gov (United States)

    Gómez-Pastor, Rocío; Pérez-Torrado, Roberto; Cabiscol, Elisa; Ros, Joaquim; Matallana, Emilia

    2012-01-09

    In the yeast biomass production process, protein carbonylation has severe adverse effects since it diminishes biomass yield and profitability of industrial production plants. However, this significant detriment of yeast performance can be alleviated by increasing thioredoxins levels. Thioredoxins are important antioxidant defenses implicated in many functions in cells, and their primordial functions include scavenging of reactive oxygen species that produce dramatic and irreversible alterations such as protein carbonylation. In this work we have found several proteins specifically protected by yeast Thioredoxin 2 (Trx2p). Bidimensional electrophoresis and carbonylated protein identification from TRX-deficient and TRX-overexpressing cells revealed that glycolysis and fermentation-related proteins are specific targets of Trx2p protection. Indeed, the TRX2 overexpressing strain presented increased activity of the central carbon metabolism enzymes. Interestingly, Trx2p specifically preserved alcohol dehydrogenase I (Adh1p) from carbonylation, decreased oligomer aggregates and increased its enzymatic activity. The identified proteins suggest that the fermentative capacity detriment observed under industrial conditions in T73 wine commercial strain results from the oxidative carbonylation of specific glycolytic and fermentation enzymes. Indeed, increased thioredoxin levels enhance the performance of key fermentation enzymes such as Adh1p, which consequently increases fermentative capacity.

  19. The role of thioredoxin reductase 1 in melanoma metabolism and metastasis.

    Science.gov (United States)

    Cassidy, Pamela B; Honeggar, Matthew; Poerschke, Robyn L; White, Karen; Florell, Scott R; Andtbacka, Robert H I; Tross, Joycelyn; Anderson, Madeleine; Leachman, Sancy A; Moos, Philip J

    2015-11-01

    Although significant progress has been made in targeted and immunologic therapeutics for melanoma, many tumors fail to respond, and most eventually progress when treated with the most efficacious targeted combination therapies thus far identified. Therefore, alternative approaches that exploit distinct melanoma phenotypes are necessary to develop new approaches for therapeutic intervention. Tissue microarrays containing human nevi and melanomas were used to evaluate levels of the antioxidant protein thioredoxin reductase 1 (TR1), which was found to increase as a function of disease progression. Melanoma cell lines revealed metabolic differences that correlated with TR1 levels. We used this new insight to design a model treatment strategy that creates a synthetic lethal interaction wherein targeting TR1 sensitizes melanoma to inhibition of glycolytic metabolism, resulting in a decrease in metastases in vivo. This approach holds the promise of a new clinical therapeutic strategy, distinct from oncoprotein inhibition. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. The crystal structure of Candida glabrata dihydrofolate reductase drives new inhibitor design toward efficacious antifungal agents

    Science.gov (United States)

    Liu, Jieying; Bolstad, David B.; Smith, Adrienne E.; Priestley, Nigel D.; Wright, Dennis L.; Anderson, Amy C.

    2008-01-01

    SUMMARY Candida glabrata is a lethal fungal pathogen resistant to many antifungal agents and has emerged as a critical target for drug discovery. Over the past several years we have been developing a class of propargyl-linked antifolates as new antimicrobials and hypothesized that these compounds could be effective inhibitors of dihydrofolate reductase (DHFR) from C. glabrata. We initially screened a small collection of these inhibitors and found modest levels of potency. Subsequently, we determined the crystal structure of C. glabrata DHFR bound to a representative inhibitor with data to 1.6 Å resolution. Using this structure, we designed and synthesized second generation inhibitors. These new inhibitors bind the C. glabrata DHFR enzyme with subnanomolar potency, display greater than 2,000-fold levels of selectivity over the human enzyme and inhibit the growth of C. glabrata at levels observed with clinically employed antifungal therapeutics. PMID:18804036

  1. Effect of Punicalagin and Resveratrol on Methionine Sulfoxide Reductase: A Possible Protective Contribution against Alzheimer's Disease.

    Science.gov (United States)

    Clementi, M E; Sampaolese, B; Lazzarino, G; Giardina, B

    2015-01-01

    Methionine sulfoxide reductase A (MsrA) has been postulated to act as a catalytic antioxidant system involved in the protection of oxidative stress-induced cell injury. MsrA has recently turned attention in coupling with the neurodegenerative disorders and in particular with Alzheimer disease. In fact this neurodegenerative disorder depends to a deposit of beta amyloid a peptide with an oxidizable methionine in position 35 which is proved able to modulate the expression to MsrA in neuronal cells. Here, we firstly provided evidence that pretreatment with Resveratrol and Punicalagin (a potent antioxidant extracted from pomegranate), up-regulate the expression and enzymatic activity of MsrA in human neuroblastoma IMR-32 cells with beta amyloid peptides. This effect determines a lowering of oxidative potential of the cells as demonstrated by the ROS measurement and a protective effect on cellular availability. Therefore we hypothesize a possible prevent role for these molecules in Alzheimer and in other neurodegenerative diseases.

  2. Characterization of S-hexylglutathione-binding proteins of human hepatocellular carcinoma: separation of enoyl-CoA isomerase from an Alpha class glutathione transferase form.

    Science.gov (United States)

    Kajihara-Kano, H; Hayakari, M; Satoh, K; Tomioka, Y; Mizugaki, M; Tsuchida, S

    1997-01-01

    Recent studies have revealed binding of mitochondrial enoyl-CoA isomerase (ECI) to S-hexylglutathione-Sepharose, an affinity matrix used for purification of glutathione transferases (GSTs), and the enzyme has been suggested to be identical with the Alpha class form of GST with a subunit molecular mass of about 30 kDa. In the present study, S-hexylglutathione-binding proteins of human hepatocellular carcinomas were characterized to examine their identity. Supernatant fractions of carcinoma and surrounding tissues were applied to an affinity column, and bound fractions were resolved into three proteins with subunit molecular masses/pI values of 33 kDa/7.0, 30 kDa/5.8 and 29 kDa/5.8 in addition to the well-characterized four GST subunits, A1, A2, M1 and P1, by two-dimensional gel electrophoresis. The proteins were further purified by chromatofocusing at pH 7.4-4.0. The 30 and 29 kDa proteins were eluted at pH 4.9 and by 1 M NaCl respectively, and could be clearly separated from each other. The 29 kDa protein exhibited a low but significant activity towards 1-chloro-2,4-dinitrobenzene (4.25 micromol/min per mg of protein) and reacted with anti-(GST A1-2) antibody, suggesting that it is a member of the GST Alpha class. The 30 kDa protein did not react with anti-GST antibodies and was identified as ECI by immunoblotting and N-terminal-amino-acid-sequencing analyses. The results thus indicated that the Alpha class GST form composed of the 29 kDa subunits and ECI are two different proteins. The 33 kDa protein was eluted from the chromatofocusing column at pH 7.0 and did not react with either anti-GST antibodies or antibodies against mitochondrial enzymes involved in the beta-oxidation of fatty acids. However, it exhibited a carbonyl reductase activity with menadione and ubiquinone, and amino acid sequences of its peptides cleaved by Staphylococcus aureus V8 proteinase were consistent with those reported for the enzyme. Thus this protein binding to S

  3. Seven novel mutations in the methylenetetrahydrofolate reductase gene and genotype/phenotype correlations in severe methylenetetrahydrofolate reductase deficiency.

    OpenAIRE

    Goyette, P; Frosst, P.; Rosenblatt, D S; ROZEN, R.

    1995-01-01

    5-Methyltetrahydrofolate, the major form of folate in plasma, is a carbon donor for the remethylation of homocysteine to methionine. This form of folate is generated from 5,10-methylenetetrahydrofolate through the action of 5,10-methylenetetrahydrofolate reductase (MTHFR), a cytosolic flavoprotein. Patients with an autosomal recessive severe deficiency of MTHFR have homocystinuria and a wide range of neurological and vascular disturbances. We have recently described the isolation of a cDNA fo...

  4. Autosomal recessive HEM/Greenberg skeletal dysplasia is caused by 3 beta-hydroxysterol delta 14-reductase deficiency due to mutations in the lamin B receptor gene.

    Science.gov (United States)

    Waterham, Hans R; Koster, Janet; Mooyer, Petra; Noort Gv, Gerard van; Kelley, Richard I; Wilcox, William R; Wanders, Ronald J A; Hennekam, Raoul C M; Oosterwijk, Jan C

    2003-04-01

    Hydrops-ectopic calcification-"moth-eaten" (HEM) or Greenberg skeletal dysplasia is an autosomal recessive chondrodystrophy with a lethal course, characterized by fetal hydrops, short limbs, and abnormal chondro-osseous calcification. We found elevated levels of cholesta-8,14-dien-3beta-ol in cultured skin fibroblasts of an 18-wk-old fetus with HEM, compatible with a deficiency of the cholesterol biosynthetic enzyme 3beta-hydroxysterol delta(14)-reductase. Sequence analysis of two candidate genes encoding putative human sterol delta(14)-reductases (TM7SF2 and LBR) identified a homozygous 1599-1605TCTTCTA-->CTAGAAG substitution in exon 13 of the LBR gene encoding the lamin B receptor, which results in a truncated protein. Functional complementation of the HEM cells by transfection with control LBR cDNA confirmed that LBR encoded the defective sterol delta(14)-reductase. Mutations in LBR recently have been reported also to cause Pelger-Huët anomaly, an autosomal dominant trait characterized by hypolobulated nuclei and abnormal chromatin structure in granulocytes. The fact that the healthy mother of the fetus showed hypolobulated nuclei in 60% of her granulocytes confirms that classic Pelger-Huët anomaly represents the heterozygous state of 3beta-hydroxysterol delta(14)-reductase deficiency.

  5. Hepatocyte Hyperproliferation upon Liver-Specific Co-disruption of Thioredoxin-1, Thioredoxin Reductase-1, and Glutathione Reductase

    Directory of Open Access Journals (Sweden)

    Justin R. Prigge

    2017-06-01

    Full Text Available Energetic nutrients are oxidized to sustain high intracellular NADPH/NADP+ ratios. NADPH-dependent reduction of thioredoxin-1 (Trx1 disulfide and glutathione disulfide by thioredoxin reductase-1 (TrxR1 and glutathione reductase (Gsr, respectively, fuels antioxidant systems and deoxyribonucleotide synthesis. Mouse livers lacking both TrxR1 and Gsr sustain these essential activities using an NADPH-independent methionine-consuming pathway; however, it remains unclear how this reducing power is distributed. Here, we show that liver-specific co-disruption of the genes encoding Trx1, TrxR1, and Gsr (triple-null causes dramatic hepatocyte hyperproliferation. Thus, even in the absence of Trx1, methionine-fueled glutathione production supports hepatocyte S phase deoxyribonucleotide production. Also, Trx1 in the absence of TrxR1 provides a survival advantage to cells under hyperglycemic stress, suggesting that glutathione, likely via glutaredoxins, can reduce Trx1 disulfide in vivo. In triple-null livers like in many cancers, deoxyribonucleotide synthesis places a critical yet relatively low-volume demand on these reductase systems, thereby favoring high hepatocyte turnover over sustained hepatocyte integrity.

  6. Selenite reduction by Shewanella oneidensis MR-1 is mediated by fumarate reductase in periplasm

    Science.gov (United States)

    Li, Dao-Bo; Cheng, Yuan-Yuan; Wu, Chao; Li, Wen-Wei; Li, Na; Yang, Zong-Chuang; Tong, Zhong-Hua; Yu, Han-Qing

    2014-01-01

    In situ reduction of selenite to elemental selenium (Se(0)), by microorganisms in sediments and soils is an important process and greatly affects the environmental distribution and the biological effects of selenium. However, the mechanism behind such a biological process remains unrevealed yet. Here we use Shewanella oneidensis MR-1, a widely-distributed dissimilatory metal-reducing bacterium with a powerful and diverse respiration capability, to evaluate the involvement of anaerobic respiration system in the microbial selenite reduction. With mutants analysis, we identify fumarate reductase FccA as the terminal reductase of selenite in periplasm. Moreover, we find that such a reduction is dependent on central respiration c-type cytochrome CymA. In contrast, nitrate reductase, nitrite reductase, and the Mtr electron transfer pathway do not work as selenite reductases. These findings reveal a previously unrecognized role of anaerobic respiration reductases of S. oneidensis MR-1 in selenite reduction and geochemical cycles of selenium in sediments and soils.

  7. The effect of occupational lead exposure on lipid peroxidation, protein carbonylation, and plasma viscosity.

    Science.gov (United States)

    Kasperczyk, Sławomir; Słowińska-Łożyńska, Ludmiła; Kasperczyk, Aleksandra; Wielkoszyński, Tomasz; Birkner, Ewa

    2015-12-01

    The aim of the study was to investigate the influence of occupational lead (Pb) exposure on lipid peroxidation, protein carbonylation, and plasma viscosity in workers. The examined group included 283 healthy male employees of manufacturing facilities using zinc and Pb. The mean blood concentrations of Pb and zinc protoporphyrin as well as the mean urine δ-aminolevulinic acid levels were used as markers of exposure for the examined group. Taking into account the obtained mean values of blood lead level, the examined group was divided into three subgroups. When comparing the control group with the subgroups, Pb exposure markers were significantly elevated in all the three subgroups. Concentrations of conjugated dienes (CD), lipid hydroperoxides, malondialdehyde (MDA), and protein carbonyl groups were also significantly increased. Conversely, the levels of total protein and protein sulfhydryls were significantly decreased in the subgroups compared with the controls. The plasma viscosity was significantly elevated in the subgroups. A dose-response between Pb levels and plasma viscosity was not observed. Pb supposedly elevates MDA and CD in a dose-dependent manner. In conclusion, occupational Pb exposure induces oxidative stress that results in lipid and protein damage. Moreover, Pb-induced oxidative stress is likely the primary factor that elevates plasma viscosity, despite decreased protein levels. © The Author(s) 2012.

  8. Determination of carbonyl compounds (acetaldehyde and formaldehyde in polyethylene terephthalate containers designated for water conservation

    Directory of Open Access Journals (Sweden)

    Redžepović Azra S.

    2012-01-01

    Full Text Available Polyethylene terephthalate (PET has in the last several years become the main packaging material for many food products, particularly carbonated beverages and bottled water, as well as for products of chemical industry (packaging of various hygiene maintenance agents, pesticides, solvents, etc.. The strength and permeability properties of PET are very good for packaging of beverages, its resistance to chemicals is high and it has a high degree of transparency. Acetaldehyde and formaldehyde are formed during the thermoforming of PET containers. After cooling, acetaldehyde and formaldehyde remain trapped in the walls of a PET bottle and may migrate into the water after filling and storage. Since there are no migration tests in Serbia prescribed for the determination of acetaldehyde and formaldehyde, the purpose of the paper is to test the quantitative contents of carbonyl compounds (acetaldehyde and formaldehyde in PET containers of different volumes, made by various manufacturers of bottled mineral carbonated and noncarbonated water, and exposed to different temperatures. In this study, the migration of acetaldehyde and formaldehyde from PET bottles into mineral carbonated and noncarbonated water was determined by high performance liquid chromatography. Taking into consideration that formaldehyde and acetaldehyde have no UV active or fluorescent group, the chromatography shall be preceded by derivatization in a closed system (due to a low boiling point of acetaldehyde and formaldehyde, which shall transform carbonyl compounds into UV active compounds.

  9. Behavior of VOCs and carbonyl compounds emission from different types of wallpapers in Korea.

    Science.gov (United States)

    Lim, Jungyun; Kim, Suejin; Kim, Arong; Lee, Wooseok; Han, Jinseok; Cha, Jun-Seok

    2014-04-17

    Emissions of volatile organic compounds (VOCs) and carbonyls from three types of commercially available wallpapers (i.e., PVC-coated, paper-backed, natural material-coated) in Korea were evaluated using a 20 L small chamber. A total of 332 products were tested for emission factors, frequencies of occurrence and composition ratios. Toluene and formaldehyde concentrations were below Korean standard values for all products; however, the total VOC (TVOC) concentrations exceeded current standards (4.0 mg/m²·h) for 30 products. The TVOC emission factor for PVC-coated wallpapers, for which polymer materials are used in the manufacturing process, was seven and 16 times higher than those of paper-backed and natural material-coated wallpapers, respectively. The detection frequencies for toluene and formaldehyde were the highest (82.5%) and fourth highest (79.5%), respectively among the 50 target chemical species. The composition ratios for BTEX ranged from 0.3% to 5.1% and unidentified VOCs, which were not qualitatively analyzed using standard gas methods, ranged from 90.2% to 94.8%. Among six carbonyl compounds (acrolein was not detected in any type of wallpaper), acetone had the highest concentrations in PVC-coated (44.6%) and paper-backed (66.6%) wallpapers. Formaldehyde emissions were highest (64.6%) for natural material-coated wallpapers, a result of the formaldehyde-based resin used in the manufacturing process for these products.

  10. Enhanced microwave absorbing properties and heat resistance of carbonyl iron by electroless plating Co

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyu, E-mail: wanghongyu07010310@163.com; Zhu, Dongmei; Zhou, Wancheng; Luo, Fa

    2015-11-01

    Co coated carbonyl iron particles (Co (CI)) are fabricated through electroless plating method, and the electromagnetic microwave absorbing properties are investigated in the frequencies during 8.2–12.4 GHz. The complex permittivity of CI particles after electroless plating Co is higher than that of raw CI particles due to improvment of the polarization process. Furthermore, according to the XRD and TG results, the Co layer can enhance the heat resistance of CI particles. The bandwidth below −10 dB can reach 3.9 GHz for the Co(CI) absorbent. The results indicate that the electroless plating Co not only enhances the absorbing properties but also improves the heat resistance of CI. - Highlights: • The Co-coated carbonyl iron Co(CI) particles were prepared by electroless plating. • The electromagnetic wave absorbing properties of Co(CI) particles were studied. • The heat treatment on the absorbing property of Co(CI) particles was studied. • The Co(CI) particles have good absorbing property when compared with CI.

  11. Slurry-phase Fischer-Tropsch synthesis and kinetic studies over supported cobalt carbonyl derived catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Withers, H.P. Jr.; Eliezer, K.F.; Mitchell, J.W. (Air Products and Chemicals, Inc., Allentown, PA (USA))

    1990-09-01

    This paper reports the preparation characterization, and performance of cobalt carbonyl cluster based catalysts for use in slurry-phase Fischer--Tropsch (FT) technology investigated. Using metal carbonyls as active metal precursors allows for the control of metal particle size on the support surface, thus offering the potential for better control of activity and selectivity of the FT reaction. Silica as the support provided the highest catalyst activities. A Co{sub 2}(CO){sub 8}/Zr(OPr){sub 4}/SiO{sub 2} catalyst (3.5% cobalt, 6.6% zirconium) was developed as the most active system in the FT slurry reactor and also gave the best liquid fuel selectivity. Selectivity patterns correlated to the Schulz--Flory prediction. These catalysts exhibited low water/gas shift activity. Diesel fuel product produced by this catalyst was high quality. A kinetic expression that took water inhibition into account was verified, yielding an activation energy of 97 kJ/mol for syngas conversion ranging from 34% to 71% at 240--280{degrees} C.

  12. Impact of silica-coating on the microwave absorption properties of carbonyl iron powder

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [School of Science, Lanzhou University of Technology, Lanzhou, Gansu 730050 (China); Feng, W.J., E-mail: wjfeng@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metal, Lanzhou University of Technology, Lanzhou 730050 (China); School of Science, Lanzhou University of Technology, Lanzhou, Gansu 730050 (China); Wang, J.S.; Zhao, X.; Zheng, W.Q. [School of Science, Lanzhou University of Technology, Lanzhou, Gansu 730050 (China); Yang, H. [State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metal, Lanzhou University of Technology, Lanzhou 730050 (China); School of Science, Lanzhou University of Technology, Lanzhou, Gansu 730050 (China)

    2015-11-01

    Microwave absorption properties, especially the band width and depth of reflection loss are highlighted as key measurement in studies of microwave absorber. In order to improve the band width and depth of reflection loss of carbonyl iron powder (CIP), we prepared SiO{sub 2} layers on the surface of CIP by using tetraethyl orthosilicate (TEOS) as a SiO{sub 2} source and 3-aminopropyl triethoxysilane (APTES) as a surface modifier. SiO{sub 2} layer was formed by the hydrolysis of TEOS. The results show that after treatment the CIP is covered by a 5–10 nm coating layer. Contrast to uncoated samples, coated samples show improved absorption properties. The minimum of reflection loss is −38.8 dB at 11 GHz and the band width of reflection loss exceeding −10 dB is from 8 GHz to 14 GHz. - Highlights: • Silica coatings were prepared on the surface of carbonyl iron powder. • Coating layers were identified by several ways. • We discussed the absorbing mechanism of coated samples. • Reflection loss was significantly improved, the width of RL exceeding −10 dB is from 8 GHz to 14 GHz.

  13. Carbonylation as a key reaction in anaerobic acetone activation by Desulfococcus biacutus.

    Science.gov (United States)

    Gutiérrez Acosta, Olga B; Hardt, Norman; Schink, Bernhard

    2013-10-01

    Acetone is activated by aerobic and nitrate-reducing bacteria via an ATP-dependent carboxylation reaction to form acetoacetate as the first reaction product. In the activation of acetone by sulfate-reducing bacteria, acetoacetate has not been found to be an intermediate. Here, we present evidence of a carbonylation reaction as the initial step in the activation of acetone by the strictly anaerobic sulfate reducer Desulfococcus biacutus. In cell suspension experiments, CO was found to be a far better cosubstrate for acetone activation than CO2. The hypothetical reaction product, acetoacetaldehyde, is extremely reactive and could not be identified as a free intermediate. However, acetoacetaldehyde dinitrophenylhydrazone was detected by mass spectrometry in cell extract experiments as a reaction product of acetone, CO, and dinitrophenylhydrazine. In a similar assay, 2-amino-4-methylpyrimidine was formed as the product of a reaction between acetoacetaldehyde and guanidine. The reaction depended on ATP as a cosubstrate. Moreover, the specific activity of aldehyde dehydrogenase (coenzyme A [CoA] acylating) tested with the putative physiological substrate was found to be 153 ± 36 mU mg(-1) protein, and its activity was specifically induced in extracts of acetone-grown cells. Moreover, acetoacetyl-CoA was detected (by mass spectrometry) after the carbonylation reaction as the subsequent intermediate after acetoacetaldehyde was formed. These results together provide evidence that acetoacetaldehyde is an intermediate in the activation of acetone by sulfate-reducing bacteria.

  14. Oxidative stress and protein carbonylation in adipose tissue - implications for insulin resistance and diabetes mellitus.

    Science.gov (United States)

    Ruskovska, Tatjana; Bernlohr, David A

    2013-10-30

    While historically considered simply as a depot for excess energy, white adipose tissue is a dynamically active endocrine organ capable of responding to a variety of efferent stimuli resulting in the synthesis and secretion of peptides, proteins and metabolites that serve as signal transducers to the peripheral and central circulation. Such regulation controls a variety of physiological processes including energy expenditure, food intake, reproductive capacity and responsiveness to insulin. Indeed, the accumulation of inflammatory cells in white adipose tissue is considered to be causative in the development of insulin resistance and eventually type 2 diabetes mellitus. A large body of evidence suggests that oxidative stress in adipose tissue not only correlates with insulin resistance but is also causative in its development. Moreover, using the available plasma oxidative stress biomarkers, many clinical studies have shown the presence of systemic oxidative stress in obese insulin resistant subjects, and its decrease after the successful treatment of obesity. In this review we emphasize the role of protein carbonylation in dysfunctional obese white adipose tissue and its metabolic implications. We focus on glutathione S-transferase A4 as the key enzyme for trans-4-hydroxy-2-nonenal and trans-4-oxo-2-nonenal removal from the cell, thus preventing protein carbonylation. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Lipid carbonyl groups terminate the hydrogen bond network of membrane-bound water.

    Science.gov (United States)

    Ohto, Tatsuhiko; Backus, Ellen H G; Hsieh, Cho-Shuen; Sulpizi, Marialore; Bonn, Mischa; Nagata, Yuki

    2015-11-19

    We present a combined experimental sum-frequency generation (SFG) spectroscopy and ab initio molecular dynamics simulations study to clarify the structure and orientation of water at zwitterionic phosphatidylcholine (PC) lipid and amine N-oxide (AO) surfactant monolayers. Simulated O-H stretch SFG spectra of water show good agreement with the experimental data. The SFG response at the PC interface exhibits positive peaks, whereas both negative and positive bands are present for the similar zwitterionic AO interface. The positive peaks at the water/PC interface are attributed to water interacting with the lipid carbonyl groups, which act as efficient hydrogen bond acceptors. This allows the water hydrogen bond network to reach, with its (up-oriented) O-H groups, into the headgroup of the lipid, a mechanism not available for water underneath the AO surfactant. This highlights the role of the lipid carbonyl group in the interfacial water structure at the membrane interface, namely, stabilizing the water hydrogen bond network.

  16. Palladium-catalyzed oxidative carbonylation of alkyl and aryl indium reagents with CO under mild conditions.

    Science.gov (United States)

    Zhao, Yingsheng; Jin, Liqun; Li, Peng; Lei, Aiwen

    2008-07-23

    CO now can react with organoindium reagents. A novel palladium-catalyzed oxidative carbonylation reaction of organoindium reagents by CO gas with desyl chloride as oxidant was developed in supplementation with the classical methods for preparation of carboxylic acid derivatives. Primary, secondary alkyl indium reagents with beta-hydrogens and aryl indium reagents were suitable substrates, and the reaction could be carried out at 60 degrees C under 50 psi CO. Carbonylation of alkyl indium reagents can occur smoothly without additional base. Although the indium reagents were prepared from corresponding Grignard reagents (at low temperature), they displayed full compatibility with various functional groups under the protic reaction conditions. Preliminary mechanistic studies including stoichiometric and catalytic reaction examination provided evidence to support the operation of the mechanism consisted of oxidative addition of deslyl chloride to Pd(0) and quick tautomerization to give a palladium enolate species II (ROPdCl), displacement of the enolate group in II by R(2)OH, followed by CO insertion to give alkoxycarbonyl palladium complex V, which undergoes transmetalation with R(1)(3)In and reductive elimination to afford the product and a Pd(0) species. In this mechanism, the alkoxycarbonyl group was transferred to the palladium center prior to the alkyl group, different from traditional ways initiated from oxidative addition of alkyl halides to a Pd(0) species.

  17. Arbutin blocks defects in the ripple phase of DMPC bilayers by changing carbonyl organization.

    Science.gov (United States)

    Frías, M A; Nicastro, A; Casado, N M C; Gennaro, A M; Díaz, S B; Disalvo, E A

    2007-05-01

    The effect of arbutin, a 4-hydroxyphenyl-beta-glucopyranoside, on dimyristoylphosphatidylcholine (DMPC) bilayers was studied by turbidimetry, EPR and FTIR spectroscopies. The disruption of DMPC multilamellar vesicles (MLV's) with monomyristoylphosphatidylcholine (lysoPC), a product of hydrolysis of phospholipase A(2) (PLA(2)), is more efficient at 18 degrees C, where DMPC MLV's are known to be in the ripple P(beta') phase, than at 10 degrees C (L(beta') flat gel phase). Disruption at 18 degrees C was inhibited by increasing concentrations of arbutin in the solution. This inhibition was correlated with the disappearance of the ripple phase in MLV's when arbutin is present. Shifts in FTIR carbonyl bands caused by arbutin or by temperature changes allow us to propose a model. It is interpreted that the changes in the water-hydrocarbon interface caused by arbutin, forcing a reaccommodation of the carbonyl groups, eliminate the topological defects in the lattice due to mismatches among regions with different area per lipid where lysoPC can insert.

  18. Toward Green Acylation of (Heteroarenes: Palladium-Catalyzed Carbonylation of Olefins to Ketones

    Directory of Open Access Journals (Sweden)

    Jie Liu

    2017-11-01

    Full Text Available Green Friedel–Crafts acylation reactions belong to the most desired transformations in organic chemistry. The resulting ketones constitute important intermediates, building blocks, and functional molecules in organic synthesis as well as for the chemical industry. Over the past 60 years, advances in this topic have focused on how to make this reaction more economically and environmentally friendly by using green acylating conditions, such as stoichiometric acylations and catalytic homogeneous and heterogeneous acylations. However, currently well-established methodologies for their synthesis either produce significant amounts of waste or proceed under harsh conditions, limiting applications. Here, we present a new protocol for the straightforward and selective introduction of acyl groups into (hetero­arenes without directing groups by using available olefins with inexpensive CO. In the presence of commercial palladium catalysts, inter- and intramolecular carbonylative C–H functionalizations take place with good regio- and chemoselectivity. Compared to classical Friedel–Crafts chemistry, this novel methodology proceeds under mild reaction conditions. The general applicability of this methodology is demonstrated by the direct carbonylation of industrial feedstocks (ethylene and diisobutene as well as of natural products (eugenol and safrole. Furthermore, synthetic applications to drug molecules are showcased.

  19. Penicitroamide, an Antimicrobial Metabolite with High Carbonylization from the Endophytic Fungus Penicillium sp. (NO. 24

    Directory of Open Access Journals (Sweden)

    Zi-Wei Feng

    2016-10-01

    Full Text Available Penicitroamide (1, a new metabolite with a new framework, was isolated from the ethyl acetate extract of the PDB (Potato Dextrose Broth medium of Penicillium sp. (NO. 24. The endophytic fungus Penicillium sp. (NO. 24 was obtained from the healthy leaves of Tapiscia sinensis Oliv. The structure of penicitroamide (1 features a bicyclo[3.2.1]octane core unit with a high degree of carbonylization (four carbonyl groups and one enol group. The chemical structure of penicitroamide (1 was elucidated by analysis of 1D-, 2D-NMR and MS data. In bioassays, penicitroamide (1 displayed antibacterial potency against two plant pathogens, Erwinia carotovora subsp. Carotovora (Jones Bersey, et al. and Sclerotium rolfsii Sacc. with MIC50 at 45 and 50 μg/mL. Compound 1 also showed 60% lethality against brine shrimp at 10 μg/mL. Penicitroamide (1 exhibited no significant activity against A549, Caski, HepG2 and MCF-7 cells with IC50 > 50 μg/mL. Finally, the possible biosynthetic pathway of penicitroamide (1 was discussed.

  20. Induction of NADPH-Cytochroune P-450 (c) Reductase in Wounded Tissues from Helianthus tuberosus Tubers

    OpenAIRE

    Agnes, Lesot; Irene, Benveniste; Marie-Paule, Hasenfratz; Francis, Durst; C.N.R.S.,Institut de Biologie Moleculaire des Plantes. Departement d'Enzymologie Cellulaire et Moieculaire, Institut de Botanique

    1990-01-01

    Cytochrome P-450 is not self-sufficient for the catalysis of monooxygenase reaction but requires NADPH and NADPH-cytochrome P-450 (c) reductase. The activity of NADPH-cytochrome P-450 reductase was strongly enhanced by wounding and aging in Jerusalem artichoke (Helianthus tuberosus L.) tuber tissues. This stimulation was correlated with the synthesis of the enzyme protein based on i) quantitation of the reductase protein by Western blotting, ii) incor-poration of [^S]methionine into the immun...

  1. A substrate-bound structure of cyanobacterial biliverdin reductase identifies stacked substrates as critical for activity

    OpenAIRE

    Takao, Haruna; Hirabayashi, Kei; Nishigaya, Yuki; Kouriki, Haruna; Nakaniwa, Tetsuko; Hagiwara, Yoshinori; Harada, Jiro; Sato, Hideaki; Yamazaki, Toshimasa; Sakakibara, Yoichi; Suiko, Masahito; Asada, Yujiro; Takahashi, Yasuhiro; Yamamoto, Ken; Fukuyama, Keiichi

    2017-01-01

    Biliverdin reductase catalyses the last step in haem degradation and produces the major lipophilic antioxidant bilirubin via reduction of biliverdin, using NAD(P)H as a cofactor. Despite the importance of biliverdin reductase in maintaining the redox balance, the molecular details of the reaction it catalyses remain unknown. Here we present the crystal structure of biliverdin reductase in complex with biliverdin and NADP+. Unexpectedly, two biliverdin molecules, which we designated the proxim...

  2. Synergistic Roles of Helicobacter pylori Methionine Sulfoxide Reductase and GroEL in Repairing Oxidant-damaged Catalase*

    Science.gov (United States)

    Mahawar, Manish; Tran, ViLinh; Sharp, Joshua S.; Maier, Robert J.

    2011-01-01

    Hypochlorous acid (HOCl) produced via the enzyme myeloperoxidase is a major antibacterial oxidant produced by neutrophils, and Met residues are considered primary amino acid targets of HOCl damage via conversion to Met sulfoxide. Met sulfoxide can be repaired back to Met by methionine sulfoxide reductase (Msr). Catalase is an important antioxidant enzyme; we show it constitutes 4–5% of the total Helicobacter pylori protein levels. msr and katA strains were about 14- and 4-fold, respectively, more susceptible than the parent to killing by the neutrophil cell line HL-60 cells. Catalase activity of an msr strain was much more reduced by HOCl exposure than for the parental strain. Treatment of pure catalase with HOCl caused oxidation of specific MS-identified Met residues, as well as structural changes and activity loss depending on the oxidant dose. Treatment of catalase with HOCl at a level to limit structural perturbation (at a catalase/HOCl molar ratio of 1:60) resulted in oxidation of six identified Met residues. Msr repaired these residues in an in vitro reconstituted system, but no enzyme activity could be recovered. However, addition of GroEL to the Msr repair mixture significantly enhanced catalase activity recovery. Neutrophils produce large amounts of HOCl at inflammation sites, and bacterial catalase may be a prime target of the host inflammatory response; at high concentrations of HOCl (1:100), we observed loss of catalase secondary structure, oligomerization, and carbonylation. The same HOCl-sensitive Met residue oxidation targets in catalase were detected using chloramine-T as a milder oxidant. PMID:21460217

  3. Enantioselective Iridium Catalyzed Carbonyl Allylation from the Alcohol or Aldehyde Oxidation Level via Transfer Hydrogenative Coupling of Allyl Acetate: Departure from Chirally Modified Allyl Metal Reagents in Carbonyl Addition

    OpenAIRE

    Kim, In Su; Ngai, Ming-Yu; Krische, Michael J.

    2008-01-01

    Under the conditions of transfer hydrogenation employing an iridium catalyst generated in situ from [Ir(cod)Cl]2, the chiral phosphine ligands (R)-BINAP or (R)-Cl,MeO-BIPHEP and m-nitrobenzoic acid, allyl acetate couples to allylic alcohols 1a-1c, aliphatic alcohols 1d-1l and benzylic alcohols 1m-1u to furnish products of carbonyl allylation 3a-3u with exceptional levels of asymmetric induction. The very same set of optically enriched carbonyl allylation products 3a-3u are accessible from ena...

  4. Complex permeability and permittivity variation of carbonyl iron rubber in the frequency range of 2 to 18 GHz

    Directory of Open Access Journals (Sweden)

    Adriana Medeiros Gama

    2010-04-01

    Full Text Available The complex dielectric permittivity (e and magnetic permeability (m of Radar Absorbing Materials (RAM based on metallic magnetic particles (carbonyl iron particles embedded in a dielectric matrix (silicon rubber have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of carbonyl iron-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the frequency is analyzed. In a general way, the results show that e´ parameter shows a more significant variation among the evaluated parameters (e”, m”, m’. The comparison of dielectric and magnetic loss tangents (e”/e” and m”/m’, respectively shows more clearly the variation of both parameters (e and m according to the frequency. It is also observed that higher carbonyl iron content fractions favor both dielectric and magnetic loss tangents.

  5. Cloning, purification, crystallization and preliminary X-ray analysis of a chimeric NADPH-cytochrome P450 reductase.

    Science.gov (United States)

    Aigrain, Louise; Pompon, Denis; Truan, Gilles; Moréra, Solange

    2009-03-01

    NADPH-cytochrome P450 reductase (CPR) is the favoured redox partner of microsomal cytochromes P450. This protein is composed of two flavin-containing domains (FMN and FAD) connected by a structured linker. An active CPR chimera consisting of the yeast FMN and human FAD domains has been produced, purified and crystallized. The crystals belonged to the monoclinic space group C2 and contained one molecule per asymmetric unit. Molecular replacement was performed using the published rat and yeast structures as search models. The initial electron-density maps revealed that the chimeric enzyme had crystallized in a conformation that differed from those of previously solved structures.

  6. Histochemical localization of glutathione dependent NBT-reductase in mouse skin.

    Science.gov (United States)

    Shukla, Y

    2001-09-01

    Localization of the glutathione dependent Nitroblue tetrazolium (NBT) reductase in fresh frozen sections of mouse skin and possible dependence of NBT reductase on tissue thiol levels has been investigated. The fresh frozen tissue sections (8 m thickness) were prepared and incubated in medium containing NBT, reduced glutathione (GSH) and phosphate buffer. The staining for GSH was performed with mercury orange. The activity of the NBT-reductase in mouse skin has been found to be localized in the areas rich in glutathione and actively proliferating area of the skin. The activity of the NBT-reductase seems to be dependent on the glutathione contents.

  7. Sucrose mimics the light induction of Arabidopsis nitrate reductase gene transcription

    DEFF Research Database (Denmark)

    Cheng, Chi-Lien; Acedo, Gregoria N; Kristensen, Michael

    1992-01-01

    Nitrate reductase, the first enzyme in nitrate assimilation, is located at the crossroad of two energy-consuming pathways: nitrate assimilation and carbon fixation. Light, which regulates the expression of many higher-plant carbon fixation genes, also regulates nitrate reductase gene expression....... Located in the cytosol, nitrate reductase obtains its reductant not from photosynthesis but from carbohydrate catabolism. This relationship prompted us to investigate the indirect role that light might play, via photosynthesis, in the regulation of nitrate reductase gene expression. We show that sucrose...

  8. The mechanism of the quinone reductase reaction of pig heart lipoamide dehydrogenase.

    Science.gov (United States)

    Vienozinskis, J; Butkus, A; Cenas, N; Kulys, J

    1990-01-01

    The relationship between the NADH:lipoamide reductase and NADH:quinone reductase reactions of pig heart lipoamide dehydrogenase (EC 1.6.4.3) was investigated. At pH 7.0 the catalytic constant of the quinone reductase reaction (kcat.) is 70 s-1 and the rate constant of the active-centre reduction by NADH (kcat./Km) is 9.2 x 10(5) M-1.s-1. These constants are almost an order lower than those for the lipoamide reductase reaction. The maximal quinone reductase activity is observed at pH 6.0-5.5. The use of [4(S)-2H]NADH as substrate decreases kcat./Km for the lipoamide reductase reaction and both kcat. and kcat./Km for the quinone reductase reaction. The kcat./Km values for quinones in this case are decreased 1.85-3.0-fold. NAD+ is a more effective inhibitor in the quinone reductase reaction than in the lipoamide reductase reaction. The pattern of inhibition reflects the shift of the reaction equilibrium. Various forms of the four-electron-reduced enzyme are believed to reduce quinones. Simple and 'hybrid ping-pong' mechanisms of this reaction are discussed. The logarithms of kcat./Km for quinones are hyperbolically dependent on their single-electron reduction potentials (E1(7]. A three-step mechanism for a mixed one-electron and two-electron reduction of quinones by lipoamide dehydrogenase is proposed. PMID:2375745

  9. Investigation of carbonyl compound sources at a rural site in the Yangtze River Delta region of China.

    Science.gov (United States)

    Wang, Ming; Chen, Wentai; Shao, Min; Lu, Sihua; Zeng, Limin; Hu, Min

    2015-02-01

    Carbonyl compounds are important intermediates in atmospheric photochemistry, but their primary sources are still not understood well. In this work, carbonyls, hydrocarbons, and alkyl nitrates were continuously measured during November 2011 at a rural site in the Yangtze River Delta region of China. Mixing ratios of carbonyls and hydrocarbons showed large fluctuations during the entire measurement. The average level for total measured volatile organic compounds during the pollution episode from 25th to 27th November, 2011 was 91.6 ppb, about 7 times the value for the clean period of 7th-8th, November, 2011. To preliminarily identify toluene sources at this site, the emission ratio of toluene to benzene (T/B) during the pollution episode was determined based on photochemical ages derived from the relationship of alkyl nitrates to their parent alkanes. The calculated T/B was 5.8 ppb/ppb, significantly higher than the values of 0.2-1.7 ppb/ppb for vehicular exhaust and other combustion sources, indicating the dominant influence of industrial emissions on ambient toluene. The contributions of industrial sources to ambient carbonyls were then calculated using a multiple linear regression fit model that used toluene and alkyl nitrates as respective tracers for industrial emission and secondary production. During the pollution episode, 18.5%, 69.0%, and 52.9% of measured formaldehyde, acetaldehyde, and acetone were considered to be attributable to industrial emissions. The emission ratios relative to toluene for formaldehyde, acetaldehyde, and acetone were determined to be 0.10, 0.20 and 0.40 ppb/ppb, respectively. More research on industrial carbonyl emission characteristics is needed to understand carbonyl sources better. Copyright © 2014. Published by Elsevier B.V.

  10. Methane to acetic acid over Cu-exchanged zeolites: mechanistic insights from a site-specific carbonylation reaction.

    Science.gov (United States)

    Narsimhan, Karthik; Michaelis, Vladimir K; Mathies, Guinevere; Gunther, William R; Griffin, Robert G; Román-Leshkov, Yuriy

    2015-02-11

    The selective low temperature oxidation of methane is an attractive yet challenging pathway to convert abundant natural gas into value added chemicals. Copper-exchanged ZSM-5 and mordenite (MOR) zeolites have received attention due to their ability to oxidize methane into methanol using molecular oxygen. In this work, the conversion of methane into acetic acid is demonstrated using Cu-MOR by coupling oxidation with carbonylation reactions. The carbonylation reaction, known to occur predominantly in the 8-membered ring (8MR) pockets of MOR, is used as a site-specific probe to gain insight into important mechanistic differences existing between Cu-MOR and Cu-ZSM-5 during methane oxidation. For the tandem reaction sequence, Cu-MOR generated drastically higher amounts of acetic acid when compared to Cu-ZSM-5 (22 vs 4 μmol/g). Preferential titration with sodium showed a direct correlation between the number of acid sites in the 8MR pockets in MOR and acetic acid yield, indicating that methoxy species present in the MOR side pockets undergo carbonylation. Coupled spectroscopic and reactivity measurements were used to identify the genesis of the oxidation sites and to validate the migration of methoxy species from the oxidation site to the carbonylation site. Our results indicate that the Cu(II)-O-Cu(II) sites previously associated with methane oxidation in both Cu-MOR and Cu-ZSM-5 are oxidation active but carbonylation inactive. In turn, combined UV-vis and EPR spectroscopic studies showed that a novel Cu(2+) site is formed at Cu/Al <0.2 in MOR. These sites oxidize methane and promote the migration of the product to a Brønsted acid site in the 8MR to undergo carbonylation.

  11. The pollution levels of BTEX and carbonyls under haze and non-haze days in Beijing, China.

    Science.gov (United States)

    Zhang, Yujie; Mu, Yujing; Meng, Fan; Li, Hong; Wang, Xuezhong; Zhang, Weiqi; Mellouki, Abdelwahid; Gao, Jian; Zhang, Xinmin; Wang, Shulan; Chai, Fahe

    2014-08-15

    The North China Plain including Beijing is frequently suffering from serious haze days in recent years. To best recognize the influence of haze days on regional air quality, the pollution levels of deleterious gases of BTEX (benzene, toluene, ethylbenzene, m,p-xylene and o-xylene) and carbonyls (formaldehyde, acetaldehyde and acetone) under haze and non-haze days were contrastively investigated during the period of September 2008-August 2010 in Beijing. In comparison with non-haze days, remarkable enhancement of BTEX and the carbonyls under haze days in winter was found, with enhancement factors of 1.9-5.7 for BTEX and of 1.5-4.2 for the carbonyls. Whereas the enhancement factors for both BTEX (1.0-3.0) and the carbonyls (1.2-1.9) under haze days in summer were relatively small. The ratios of each BTEX to CO under both haze days and non-haze days exhibited a minimal value in the afternoon, whereas maximal values for the ratios of the carbonyls to CO were usually found in the afternoon. The ratios of each BTEX to CO were extremely greater under haze days than those under non-haze days in winter, but no evident difference was found in summer. The ratios of each carbonyl under both haze days and non-haze days in summer were at least a factor of 2 greater than those in winter and only enhancement of the ratios under haze days was found in winter. The remarkably higher ratios of ethylbenzene to m,p-xylene under haze days than non-haze days in both winter and summer revealed high reactivity of photochemical reactions initiated by OH radicals under haze days. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

    Directory of Open Access Journals (Sweden)

    Peng Meng

    2017-01-01

    Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

  13. Enhanced anti-Diastereo- and Enantioselectivity in Alcohol Mediated Carbonyl Crotylation Using an Isolable Single Component Iridium Catalyst

    Science.gov (United States)

    Gao, Xin; Townsend, Ian A.; Krische, Michael J.

    2011-01-01

    The cyclometallated iridium complex (S)-I derived from [Ir(cod)Cl]2, 4-cyano-3-nitrobenzoic acid, allyl acetate and (S)-SEGPHOS is conveniently isolated by precipitation or through conventional silica gel flash chromatography. This single component precatalyst allows alcohol mediated carbonyl crotylations to be performed at significantly lower temperature, resulting in enhanced levels of anti-diastereo- and enantioselectivity. Most significantly, the chromatographically isolated precatalyst (S)-I enables carbonyl crotylations that are not possible under previously reported conditions involving in situ generation of (S)-I. PMID:21375283

  14. 1-Ethyl-3-methylimidazolium acetate as a highly efficient organocatalyst for cyanosilylation of carbonyl compounds with trimethylsilyl cyanide

    Science.gov (United States)

    Ullah, Bakhtar; Chen, Jingwen; Zhang, Zhiguo; Xing, Huabin; Yang, Qiwei; Bao, Zongbi; Ren, Qilong

    2017-02-01

    1-Ethyl-3-methylimidazolium acetate is introduced as a robust organocatalyst for solvent-free cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (TMSCN). The catalyst loading can be reduced to as low as 0.1-0.0001 mol % under mild reaction conditions, giving considerably high TOF values from 10,843 h-1 to 10,602,410 h-1 in the field of organocatalyzed transformations. The present protocol not only tolerates with extensive carbonyl compounds but also provides somewhat insight into the mechanism of ionic liquids (ILs)-catalyzed reactions.

  15. Investigation into the Effects of Boron on Liver Tissue Protein Carbonyl, MDA, and Glutathione Levels in Endotoxemia.

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    Balabanlı, Barbaros; Balaban, Tuba

    2015-10-01

    Endotoxin has been known to cause the formation and damage of free radical. The importance of boron for human life is increasing each passing day, and its consuming fields are continuing to expand due to the advances in science and technology. Therefore, in our study, we intended to investigate into the effects of boron on liver tissue oxidative events. Eighteen male Wistar albino rats were randomly separated into three equal groups in the experiments; control group, boron + endotoxin group, and endotoxin group. Dissolved in distilled water, boric acid (100 mg/kg) was administered to boron + endotoxin group via gavage procedure for 28 days. Only distilled water was administered to control and endotoxin groups via gavage procedure for 28 days. Then 4 mg/kg endotoxin (LPS; Escherichia coli 0111:B4) was intraperitoneally (ip) administered to boron + endotoxin and endotoxin groups on the 28th day. Sterile saline was injected into control group on the 28th day (ip). Malondialdehyde (MDA), which is the end product of lipid peroxidation in liver tissues, protein carbonyl compounds (PC), which are protein oxidization markers, and glutathione (GSH) levels were measured spectrophotometrically. The results were compared with Mann-Whitney U test. When boron + endotoxin group is compared with endotoxin group, PC levels of endotoxin group showed a significant increase. When GSH levels are compared, GSH level in boron + endotoxin group decreased according to endotoxin group. Variations among all groups in MDA levels were found to be statistically insignificant. We are of the opinion that endotoxin affects the proteins by forming free radicals, and boron may also cause the structural and/or functional changes in proteins in order to protect proteins from oxidization.

  16. Screening of thiourea derivatives and carbonyl-2-aminothiazole derivatives for potential CCR4 antagonists using capillary zone electrophoresis.

    Science.gov (United States)

    Zhang, Shuyu; Qi, Hui; Yakufu, Pazilaiti; Zhao, Fang; Ling, Xiaomei; Xiao, Junhai; Wang, Ying

    2011-01-01

    CC chemokine receptor 4 (CCR4) is a kind of G-protein-coupled receptors with a characteristic seven-transmembrane structure and selectively expressed on Th2-type CD4+ T-cells. CCR4 has been identified as a potentially important drug target for the treatment of T cell-mediated allergic inflammatory diseases. In this study, a novel series of CCR4 antagonists were screened by investigating the interactions between the compounds and the human CCR4 N-terminal peptide ML40 using capillary zone electrophoresis (CZE) for the first time. Both qualitative and quantitative characterizations of the compound-peptide binding were determined. The results showed that, compared with positive control, ten of the compounds were interacted with ML40, which were A3C223, A3C231, A4C238, A3C241, A4C241, A4C239, ZXF0337, ZXF0432, ZXF0519 and ZXF0637A, and their binding constants were calculated from the Scatchard plot by regression. The binding constants of the compounds to ML40 were calculated and the binding constant of ZXF0432 was the largest among them [(7.6334±0.1907)×10(4)M(-1)]. Here, a sensitive and selective high-performance analytical method based on CZE was developed for screening of thiourea derivatives and C-arbonyl-2-aminothiazole derivatives for potential CCR4 antagonists for the first time. The methodology presented should be generally applicable to study compounds-ML40 interactions as a powerful, sensitive and fast screening method for CCR4 antagonist discovery. Copyright © 2010 Elsevier B.V. All rights reserved.

  17. Carbohydrate restriction and dietary cholesterol modulate the expression of HMG-CoA reductase and the LDL receptor in mononuclear cells from adult men

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    Volek Jeff S

    2007-11-01

    Full Text Available Abstract The liver is responsible for controlling cholesterol homeostasis in the body. HMG-CoA reductase and the LDL receptor (LDL-r are involved in this regulation and are also ubiquitously expressed in all major tissues. We have previously shown in guinea pigs that there is a correlation in gene expression of HMG-CoA reductase and the LDL-r between liver and mononuclear cells. The present study evaluated human mononuclear cells as a surrogate for hepatic expression of these genes. The purpose was to evaluate the effect of dietary carbohydrate restriction with low and high cholesterol content on HMG-CoA reductase and LDL-r mRNA expression in mononuclear cells. All subjects were counseled to consume a carbohydrate restricted diet with 10–15% energy from carbohydrate, 30–35% energy from protein and 55–60% energy from fat. Subjects were randomly assigned to either EGG (640 mg/d additional dietary cholesterol or SUB groups [equivalent amount of egg substitute (0 dietary cholesterol contributions per day] for 12 weeks. At the end of the intervention, there were no changes in plasma total or LDL cholesterol (LDL-C compared to baseline (P > 0.10 or differences in plasma total or LDL-C between groups. The mRNA abundance for HMG-CoA reductase and LDL-r were measured in mononuclear cells using real time PCR. The EGG group showed a significant decrease in HMG-CoA reductase mRNA (1.98 ± 1.26 to 1.32 ± 0.92 arbitrary units P

  18. Susceptibility of the antioxidant selenoenyzmes thioredoxin reductase and glutathione peroxidase to alkylation-mediated inhibition by anticancer acylfulvenes.

    Science.gov (United States)

    Liu, Xiaodan; Pietsch, Kathryn E; Sturla, Shana J

    2011-05-16

    Selenium, in the form of selenocysteine, is a critical component of some major redox-regulating enzymes, including thioredoxin reductase (TrxR) and glutathione peroxidase (Gpx). TrxR has emerged as an anticancer target for drug development due to its elevated expression level in many aggressive human tumors. Acylfulvenes (AFs) are semisynthetic derivatives of the natural product illudin S and display improved cytotoxic selectivity profiles. AF and illudin S alkylate cellular macromolecules. Compared to AFs, illudin S more readily reacts with thiol-containing small molecules such as cysteine, glutathione, and cysteine-containing peptides. However, a previous study indicates that the reactivity of AFs and illudin S with glutathione reductase, a thiol-containing enzyme, is inversely correlated with the reactivity toward small molecule thiols. In this study, we investigate mechanistic aspects underlying the enzymatic and cellular effects of the AFs and illudin S on thioredoxin reductase. Both AF and HMAF were found to inhibit mammalian TrxR in the low- to submicromolar range, but illudin S was significantly less potent. TrxR inhibition by AFs was shown to be irreversible, concentration- and time-dependent, and mediated by alkylation of C-terminus active site Sec/Cys residues. In contrast, neither AFs nor illudin S inhibits Gpx, demonstrating that enzyme structure-specific small molecule interactions have a significant influence over the inherent reactivity of the Sec residue. In human cancer cells, TrxR activity can be inhibited by low micromolar concentrations of all three drugs. Finally, it was demonstrated that preconditioning cells by the addition of selenite to the cell culture media results in an enhancement in cell sensitivity toward AFs. These data suggest potential strategies for increasing drug activity by combination treatments that promote selenium enzyme activity.

  19. Anomalous Behavior Observed upon Annealing and Photodetachment of Anionic Copper Carbonyl Clusters in Argon Matrices

    Science.gov (United States)

    Ludwig, Ryan M.; Moore, David T.

    2014-06-01

    Using matrix isolation FTIR, we have observed the formation of anionic copper carbonyl complexes [Cu(CO)n]- (n=1-3) following co-deposition of Cu- and counter-cations (Ar+ or Kr+) into argon matrices doped with CO. When the deposition is carried out at 20 K, weak bands corresponding to the neutral copper carbonyl complexes Cu(CO)n (n=1-3) are also observed, and these grow in steadily as the matrix is annealed up to 30 K. This is in contrast to what is observed at 10 K (c.f. ISMS 2014 abstract #P631), where no appreciable neutral bands are observed, and indicates that some neutralization occurs during the formation of the complexes in the 20 K matrix. In addition, sharp peaks not previously observed grow in around the anionic bands upon annealing to 30 K; this is somewhat odd, since annealing typically simplifies the spectra of matrix samples as kinetically trapped metastable species relax to more stable forms. In this case, higher-resolution (0.125 wn) spectra reveal considerable new fine structure, with 5 and 20 peaks appearing in the regions of the mono- and tricarbonyl anions, respectively, each of which nominally has but a single IR-active CO-stretching mode. These new features are tentatively assigned (at least in part) to electric-field-induced splitting arising from long-range interactions with cationic species in the matrix. A second anomalous feature of these spectra is that, upon photodetachment, several new bands are observed in the region of the neutral copper carbonyl species. Upon annealing these bands then disappear, with concomitant growth of the expected neutral bands. This behavior raises the exciting possibility that these transient bands represent metastable "vertical detachment products", where the neutral species has been kinetically trapped by the matrix in the geometry of the anion. Evidence supporting this interpretation will be presented. Funding support from NSF CAREER Award CHE-0955637 is gratefully acknowledged Ryan M. Ludwig and David

  20. Hydrothermal synthesis of carbonyl iron-carbon nanocomposite: Characterization and electromagnetic performance

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    Hakimeh Pourabdollahi

    Full Text Available In this research, the electromagnetic absorption properties of the carbonyl iron-carbon (CI/C nanocomposite prepared via hydrothermal reaction using glucose as carbon precursor was studied in the range of 8.2–12.4 GHz. In hydrothermal reaction, glucose solution containing CI particles, placed in autoclave for 4 h under 453 K. Using surface coating technology is a method that prevents Cl oxidation and improves CI electromagnetic absorption. The structure, morphology and magnetic performances of the prepared nanocomposites were characterized by X-ray diffraction (XRD, energy dispersive spectrometry (EDS, transmission electron microscopy (TEM and vibrating sample magnetometer (VSM. The electromagnetic properties including complex permittivity (εr, the permeability (µr, dielectric loss, magnetic loss, reflection loss, and attenuation constant were investigated using a vector network analyzer. For The CI/C nanocomposite, the bandwidth of −10 dB and −20 dB were obtained in the frequency range of 9.8–12.4 and 11.0–11.8 GHz, respectively. As well as, the reflection loss was −46.69 dB at the matching frequency of 11.5 GHz, when the matching thickness was 1.3 mm. While for CI particles the reflection loss for 4.4 mm thickness was −16.86 dB at the matching frequency of 12.3 GHz. The results indicate that the existence layer of carbon on carbonyl iron enhance the electromagnetic absorbing properties. Therefore, this nanocomposite can be suitable for in the radar absorbing coatings. Keywords: Hydrothermal synthesis, Carbonyl iron-carbon nanocomposite, Microwave absorption, Reflection loss