WorldWideScience

Sample records for catalytic subunit pris

  1. Venskabets pris

    DEFF Research Database (Denmark)

    Thyssen, Ole

    2013-01-01

    Anmeldelse af Asger Baunsbak-Jensen: I venskabets spejl. 91 sider. Vejl. pris 220 kr. (Jensen & Dalgaard, 2013).......Anmeldelse af Asger Baunsbak-Jensen: I venskabets spejl. 91 sider. Vejl. pris 220 kr. (Jensen & Dalgaard, 2013)....

  2. First inactive conformation of CK2 alpha, the catalytic subunit of protein kinase CK2

    DEFF Research Database (Denmark)

    Raaf, Jennifer; Issinger, Olaf-Georg; Niefind, Karsten

    2009-01-01

    The Ser/Thr kinase casein kinase 2 (CK2) is a heterotetrameric enzyme composed of two catalytic chains (CK2alpha, catalytic subunit of CK2) attached to a dimer of two noncatalytic subunits (CK2beta, noncatalytic subunit of CK2). CK2alpha belongs to the superfamily of eukaryotic protein kinases...

  3. Prokaryotic expression of Chinese bovine enterokinase catalytic subunit

    Institute of Scientific and Technical Information of China (English)

    黄鹤; 赵阳; 甘一如

    2004-01-01

    Background To express in vitro the bovine enterokinase catalytic subunit (EKL ) protein, which could be used in the future for the cleavage and purification of fusion proteins. Methods Bovine enterokinase catalytic subunit cDNA was obtained by RT-PCR from the duodenal mucosa of a bovine obtained at a wholesale market, and then cloned into a pUCmT cloning vector and sequenced. The desired gene fragment was inserted into a pET39b expression plasmid and the recombinant vector pET39b-EKL was transformed into E. coli BL21 (DE3). Protein expression was induced using IPTG. The recombinant DsbA-EK, was purified with His · Tag affinity chromatography, and its bioactivity was analyzed. Results Compared with the sequence deposited in GenBank, the sequence of the EKL gene cloned in the present study is correct. It was also confirmed that the nucleotide sequence of expression plasmid pET39b-EKL was correct at the conjunction site between the recombinant DNA 5'terminal multi-cloning site and the recombinant fragment. SDS-PAGE analysis indicated that the target product was about 65 kDa and represented 28% of total cell protein. Purified recombinant protein was obtained by metal chelating chromatography using a NJ-IDA resin, After desalting and changing the buffer, the crude kinase was incubated at 21℃ overnight and shown to have a high autocatalytic cleavage activity. Conclusion The EKE gene from a Chinese bovine has been cloned successfully and expressed. This investigation has layed the foundation for future enterokinase activity research and for further large-scale application of expression products.

  4. trt-1 is the Caenorhabditis elegans catalytic subunit of telomerase.

    Directory of Open Access Journals (Sweden)

    2006-02-01

    Full Text Available Mutants of trt-1, the Caenorhabditis elegans telomerase reverse transcriptase, reproduce normally for several generations but eventually become sterile as a consequence of telomere erosion and end-to-end chromosome fusions. Telomere erosion and uncapping do not cause an increase in apoptosis in the germlines of trt-1 mutants. Instead, late-generation trt-1 mutants display chromosome segregation defects that are likely to be the direct cause of sterility. trt-1 functions in the same telomere replication pathway as mrt-2, a component of the Rad9/Rad1/Hus1 (9-1-1 proliferating cell nuclear antigen-like sliding clamp. Thus, the 9-1-1 complex may be required for telomerase to act at chromosome ends in C. elegans. Although telomere erosion limits replicative life span in human somatic cells, neither trt-1 nor telomere shortening affects postmitotic aging in C. elegans. These findings illustrate effects of telomere dysfunction in C. elegans mutants lacking the catalytic subunit of telomerase, trt-1.

  5. Structure of the Tribolium castaneum Telomerase Catalytic Subunit TERT

    Energy Technology Data Exchange (ETDEWEB)

    Gillis,A.; Schuller, A.; Skordalakes, E.

    2008-01-01

    A common hallmark of human cancers is the overexpression of telomerase, a ribonucleoprotein complex that is responsible for maintaining the length and integrity of chromosome ends. Telomere length deregulation and telomerase activation is an early, and perhaps necessary, step in cancer cell evolution. Here we present the high-resolution structure of the Tribolium castaneum catalytic subunit of telomerase, TERT. The protein consists of three highly conserved domains, organized into a ring-like structure that shares common features with retroviral reverse transcriptases, viral RNA polymerases and B-family DNA polymerases. Domain organization places motifs implicated in substrate binding and catalysis in the interior of the ring, which can accommodate seven to eight bases of double-stranded nucleic acid. Modelling of an RNA-DNA heteroduplex in the interior of this ring demonstrates a perfect fit between the protein and the nucleic acid substrate, and positions the 3'-end of the DNA primer at the active site of the enzyme, providing evidence for the formation of an active telomerase elongation complex.

  6. Localization of the catalytic subunit of cyclic AMP-dependent. Protein kinase in cultured cells using a specific antibody

    OpenAIRE

    1982-01-01

    We developed a specific antibody to the catalytic subunit (C-subunit) of cyclic AMP-dependent protein kinase and used it to localize C- subunit in cultured cells. C-subunit antigen was purified from bovine cardiac muscle and cross-linked to hemocyanin with glutaraldehyde. Immunized goat serum showed a low titer of antibody after boosting; it was enriched 100-fold by affinity chromatography on catalytic subunit- Sepharose. The antibody immunoprecipitated C-subunit from type I and type II holoe...

  7. Power Reactor Information System (PRIS)

    International Nuclear Information System (INIS)

    The IAEA has been collecting Operating Experience data for Nuclear Power Plants of the IAEA Member States since 1970. In order to facilitate an analysis of nuclear power plant performance as well as to produce relevant publications, all previously collected data supplied from the questionnaires were computerized in 1980 and the Power Reactor Information System was implemented. PRIS currently contains production records for the years up to and including 1990 and about 98% of the reactors-years operating experience in the world is contained in PRIS. (orig.)

  8. Power reactor information system (PRIS)

    International Nuclear Information System (INIS)

    Since the very beginning of commercial operation of nuclear power plants, the nuclear power industry worldwide has accumulated more than 5000 reactor years of experience. The IAEA has been collecting Operating Experience data for Nuclear Power Plants since 1970 which were computerized in 1980. The Agency has undertaken to make Power Reactor Information System (PRIS) available on-line to its Member States. The aim of this publication is to provide the users of PRIS from their terminals with description of data base and communication systems and to show the methods of accessing the data

  9. Functional Diversification of Maize RNA Polymerase IV and V subtypes via Alternative Catalytic Subunits

    Energy Technology Data Exchange (ETDEWEB)

    Haag, Jeremy R.; Brower-Toland, Brent; Krieger, Elysia K.; Sidorenko, Lyudmila; Nicora, Carrie D.; Norbeck, Angela D.; Irsigler, Andre; LaRue, Huachun; Brzeski, Jan; Mcginnis, Karen A.; Ivashuta, Sergey; Pasa-Tolic, Ljiljana; Chandler, Vicki L.; Pikaard, Craig S.

    2014-10-01

    Unlike nuclear multisubunit RNA polymerases I, II, and III, whose subunit compositions are conserved throughout eukaryotes, plant RNA polymerases IV and V are nonessential, Pol II-related enzymes whose subunit compositions are still evolving. Whereas Arabidopsis Pols IV and V differ from Pol II in four or five of their 12 subunits, respectively, and differ from one another in three subunits, proteomic ana- lyses show that maize Pols IV and V differ from Pol II in six subunits but differ from each other only in their largest subunits. Use of alternative catalytic second subunits, which are nonredundant for development and paramutation, yields at least two sub- types of Pol IV and three subtypes of Pol V in maize. Pol IV/Pol V associations with MOP1, RMR1, AGO121, Zm_DRD1/CHR127, SHH2a, and SHH2b extend parallels between paramutation in maize and the RNA-directed DNA methylation pathway in Arabidopsis.

  10. Two Arabidopsis ADP-glucose pyrophosphorylase large subunits (APL1 and APL2) are catalytic.

    Science.gov (United States)

    Ventriglia, Tiziana; Kuhn, Misty L; Ruiz, Ma Teresa; Ribeiro-Pedro, Marina; Valverde, Federico; Ballicora, Miguel A; Preiss, Jack; Romero, José M

    2008-09-01

    ADP-glucose (Glc) pyrophosphorylase (ADP-Glc PPase) catalyzes the first committed step in starch biosynthesis. Higher plant ADP-Glc PPase is a heterotetramer (alpha(2)beta(2)) consisting of two small and two large subunits. There is increasing evidence that suggests that catalytic and regulatory properties of the enzyme from higher plants result from the synergy of both types of subunits. In Arabidopsis (Arabidopsis thaliana), two genes encode small subunits (APS1 and APS2) and four large subunits (APL1-APL4). Here, we show that in Arabidopsis, APL1 and APL2, besides their regulatory role, have catalytic activity. Heterotetramers formed by combinations of a noncatalytic APS1 and the four large subunits showed that APL1 and APL2 exhibited ADP-Glc PPase activity with distinctive sensitivities to the allosteric activator (3-phosphoglycerate). Mutation of the Glc-1-P binding site of Arabidopsis and potato (Solanum tuberosum) isoforms confirmed these observations. To determine the relevance of these activities in planta, a T-DNA mutant of APS1 (aps1) was characterized. aps1 is starchless, lacks ADP-Glc PPase activity, APS1 mRNA, and APS1 protein, and is late flowering in long days. Transgenic lines of the aps1 mutant, expressing an inactivated form of APS1, recovered the wild-type phenotype, indicating that APL1 and APL2 have catalytic activity and may contribute to ADP-Glc synthesis in planta. PMID:18614708

  11. Two Arabidopsis ADP-Glucose Pyrophosphorylase Large Subunits (APL1 and APL2) Are Catalytic1

    Science.gov (United States)

    Ventriglia, Tiziana; Kuhn, Misty L.; Ruiz, Ma Teresa; Ribeiro-Pedro, Marina; Valverde, Federico; Ballicora, Miguel A.; Preiss, Jack; Romero, José M.

    2008-01-01

    ADP-glucose (Glc) pyrophosphorylase (ADP-Glc PPase) catalyzes the first committed step in starch biosynthesis. Higher plant ADP-Glc PPase is a heterotetramer (α2β2) consisting of two small and two large subunits. There is increasing evidence that suggests that catalytic and regulatory properties of the enzyme from higher plants result from the synergy of both types of subunits. In Arabidopsis (Arabidopsis thaliana), two genes encode small subunits (APS1 and APS2) and four large subunits (APL1–APL4). Here, we show that in Arabidopsis, APL1 and APL2, besides their regulatory role, have catalytic activity. Heterotetramers formed by combinations of a noncatalytic APS1 and the four large subunits showed that APL1 and APL2 exhibited ADP-Glc PPase activity with distinctive sensitivities to the allosteric activator (3-phosphoglycerate). Mutation of the Glc-1-P binding site of Arabidopsis and potato (Solanum tuberosum) isoforms confirmed these observations. To determine the relevance of these activities in planta, a T-DNA mutant of APS1 (aps1) was characterized. aps1 is starchless, lacks ADP-Glc PPase activity, APS1 mRNA, and APS1 protein, and is late flowering in long days. Transgenic lines of the aps1 mutant, expressing an inactivated form of APS1, recovered the wild-type phenotype, indicating that APL1 and APL2 have catalytic activity and may contribute to ADP-Glc synthesis in planta. PMID:18614708

  12. PRIS-WEDAS. User’s Manual to the Web Enabled Data Acquisition System for PRIS

    International Nuclear Information System (INIS)

    The user manual for the Web Enabled Data Acquisition System (WEDAS), a system that supports the Power Reactor Information System (PRIS), provides instructions, guidelines and detailed definitions for each of the data items required for PRIS. The purpose of this manual is to ensure PRIS performance data are collected consistently and that the required quality of data collection is ensured. This PRIS-WEDAS user’s manual replaces reporting instructions published in the IAEA Technical Reports Series No. 428

  13. Functional Diversification of Maize RNA Polymerase IV and V Subtypes via Alternative Catalytic Subunits

    Directory of Open Access Journals (Sweden)

    Jeremy R. Haag

    2014-10-01

    Full Text Available Unlike nuclear multisubunit RNA polymerases I, II, and III, whose subunit compositions are conserved throughout eukaryotes, plant RNA polymerases IV and V are nonessential, Pol II-related enzymes whose subunit compositions are still evolving. Whereas Arabidopsis Pols IV and V differ from Pol II in four or five of their 12 subunits, respectively, and differ from one another in three subunits, proteomic analyses show that maize Pols IV and V differ from Pol II in six subunits but differ from each other only in their largest subunits. Use of alternative catalytic second subunits, which are nonredundant for development and paramutation, yields at least two subtypes of Pol IV and three subtypes of Pol V in maize. Pol IV/Pol V associations with MOP1, RMR1, AGO121, Zm_DRD1/CHR127, SHH2a, and SHH2b extend parallels between paramutation in maize and the RNA-directed DNA methylation pathway in Arabidopsis.

  14. Cyclic AMP-dependent protein kinase I: Cyclic nucleotide binding, structural changes, and release of the catalytic subunits

    OpenAIRE

    Smith, Stephen B.; White, Hillary D.; Siegel, Jeffrey B.; Krebs, Edwin G.

    1981-01-01

    Type I cyclic AMP (cAMP)-dependent protein kinase is composed of a dimeric regulatory subunit (R2) and two catalytic subunits (C subunits). The R2 dimer binds four cAMP molecules to release the two C subunits. To characterize the cAMP binding sites and elucidate their role in the release of the C subunits, the R2 dimer has been studied by equilibrium methods. The cAMP titration of R2 was monitored by endogenous tryptophan fluorescence, and the results suggest one class of binding sites. The t...

  15. The catalytic and the RNA subunits of human telomerase are required to immortalize equid primary fibroblasts.

    Science.gov (United States)

    Vidale, Pamela; Magnani, Elisa; Nergadze, Solomon G; Santagostino, Marco; Cristofari, Gael; Smirnova, Alexandra; Mondello, Chiara; Giulotto, Elena

    2012-10-01

    Many human primary somatic cells can be immortalized by inducing telomerase activity through the exogenous expression of the human telomerase catalytic subunit (hTERT). This approach has been extended to the immortalization of cell lines from several mammals. Here, we show that hTERT expression is not sufficient to immortalize primary fibroblasts from three equid species, namely donkey, Burchelli's zebra and Grevy's zebra. In vitro analysis of a reconstituted telomerase composed by hTERT and an equid RNA component of telomerase (TERC) revealed a low activity of this enzyme compared to human telomerase, suggesting a low compatibility of equid and human telomerase subunits. This conclusion was also strengthened by comparison of human and equid TERC sequences, which revealed nucleotide differences in key regions for TERC and TERT interaction. We then succeeded in immortalizing equid fibroblasts by expressing hTERT and hTERC concomitantly. Expression of both human telomerase subunits led to telomerase activity and telomere elongation, indicating that human telomerase is compatible with the other equid telomerase subunits and proteins involved in telomere metabolism. The immortalization procedure described herein could be extended to primary cells from other mammals. The availability of immortal cells from endangered species could be particularly useful for obtaining new information on the organization and function of their genomes, which is relevant for their preservation.

  16. Cloning and expression of the gene encoding catalytic subunit of thermostable glucose dehydrogenase from Burkholderia cepacia in Escherichia coli.

    Science.gov (United States)

    Inose, Ken; Fujikawa, Masako; Yamazaki, Tomohiko; Kojima, Katsuhiro; Sode, Koji

    2003-02-21

    We have cloned a 1620-nucleotide gene encoding the catalytic subunit (alpha subunit) of a thermostable glucose dehydrogenase (GDH) from Burkholderia cepacia. The FAD binding motif was found in the N-terminal region of the alpha subunit. The deduced primary structure of the alpha subunit showed about 48% identity to the catalytic subunits of sorbitol dehydrogenase (SDH) from Gluconobacter oxydans and 2-keto-D-gluconate dehydrogenases (2KGDH) from Erwinia herbicola and Pantoea citrea. The alpha subunit of B. cepacia was expressed in Escherichia coli in its active water-soluble form, showing maximum dye-mediated GDH activity at 70 degrees C, retaining high thermal stability. A putative open reading frame (ORF) of 507 nucleotides was also found upstream of the alpha subunit encoding an 18-kDa peptide, designated as gamma subunit. The deduced primary structure of gamma subunit showed about 30% identity to the small subunits of the SDH from G. oxydans and 2KGDHs from E. herbicola and P. citrea. PMID:12573242

  17. Effect of antisense oligonucleotides targeting telomerase catalytic subunit on tumor cell proliferationin vitro

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    To screen specific antitumor drugs targeting telomerase catalytic subunit (hEST2), 12 different hEST2 antisense oligonucleotides were designed based on hEST2 mRNA second structure and transfected into tumor cell lines by the lipofectin-mediated method. Cell growth activity was evaluated by MTT assay. hEST212 was picked out and its specificity, antitumor tree and continuous effect were analyzed. The results showed that hEST212 had promising antitumor activity in vitro, hEST2 can be used as a pratical target and an antisense drug candidate for cancer.

  18. Structural Basis for Telomerase Catalytic Subunit TERT Binding to RNA Template and Telomeric DNA

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M.; Gillis, A; Futahashi, M; Fujiwara, H; Skordalakes, E

    2010-01-01

    Telomerase is a specialized DNA polymerase that extends the 3{prime} ends of eukaryotic linear chromosomes, a process required for genomic stability and cell viability. Here we present the crystal structure of the active Tribolium castaneum telomerase catalytic subunit, TERT, bound to an RNA-DNA hairpin designed to resemble the putative RNA-templating region and telomeric DNA. The RNA-DNA hybrid adopts a helical structure, docked in the interior cavity of the TERT ring. Contacts between the RNA template and motifs 2 and B{prime} position the solvent-accessible RNA bases close to the enzyme active site for nucleotide binding and selectivity. Nucleic acid binding induces rigid TERT conformational changes to form a tight catalytic complex. Overall, TERT-RNA template and TERT-telomeric DNA associations are remarkably similar to those observed for retroviral reverse transcriptases, suggesting common mechanistic aspects of DNA replication between the two families of enzymes.

  19. Evolutionary paths of the cAMP-dependent protein kinase (PKA catalytic subunits.

    Directory of Open Access Journals (Sweden)

    Kristoffer Søberg

    Full Text Available 3',5'-cyclic adenosine monophosphate (cAMP dependent protein kinase or protein kinase A (PKA has served as a prototype for the large family of protein kinases that are crucially important for signal transduction in eukaryotic cells. The PKA catalytic subunits Cα and Cβ, encoded by the two genes PRKACA and PRKACB, respectively, are among the best understood and characterized human kinases. Here we have studied the evolution of this gene family in chordates, arthropods, mollusks and other animals employing probabilistic methods and show that Cα and Cβ arose by duplication of an ancestral PKA catalytic subunit in a common ancestor of vertebrates. The two genes have subsequently been duplicated in teleost fishes. The evolution of the PRKACG retroposon in simians was also investigated. Although the degree of sequence conservation in the PKA Cα/Cβ kinase family is exceptionally high, a small set of signature residues defining Cα and Cβ subfamilies were identified. These conserved residues might be important for functions that are unique to the Cα or Cβ clades. This study also provides a good example of a seemingly simple phylogenetic problem which, due to a very high degree of sequence conservation and corresponding weak phylogenetic signals, combined with problematic nonphylogenetic signals, is nontrivial for state-of-the-art probabilistic phylogenetic methods.

  20. Neuron-specific regulation of class I PI3K catalytic subunits and their dysfunction in brain disorders

    Directory of Open Access Journals (Sweden)

    Christina eGross

    2014-02-01

    Full Text Available The PI3K complex plays important roles in virtually all cells of the body. The enzymatic activity of PI3K to phosphorylate phosphoinositides in the membrane is mediated by a group of catalytic and regulatory subunits. Among those, the class I catalytic subunits, p110α, p110β, p110γ and p110δ, have recently drawn attention in the neuroscience field due to their specific dysregulation in diverse brain disorders. While in non-neuronal cells these catalytic subunits may have partially redundant functions, there is increasing evidence that in neurons their roles are more specialized, and confined to distinct receptor-dependent pathways. This review will summarize the emerging role of class I PI3K catalytic subunits in neurotransmitter-regulated neuronal signaling, and their dysfunction in a variety of neurological diseases, including fragile X syndrome, schizophrenia and epilepsy. We will discuss recent literature describing the use of PI3K subunit-selective inhibitors to rescue brain disease-associated phenotypes in in vitro and animal models. These studies give rise to the exciting prospect that these drugs, originally designed for cancer treatment, may be repurposed as therapeutic drugs for brain disorders in the future.

  1. Entre prisões da imagem, imagens da prisão

    Directory of Open Access Journals (Sweden)

    Fernanda Spanier Amador

    2014-04-01

    Full Text Available O artigo discute a temática das prisões, da imagem e da subjetividade. Pensando na direção das análises foucaultianas de que as prisões estão estabelecidas nos mais ínfimos espaços da vida cotidiana pelas práticas disciplinares e por jogos de visibilidade e enunciabilidade, pergunta-se: como a experimentação de produção de imagens digitais a respeito do trabalho na prisão, por parte de trabalhadores penitenciários, pode criar um plano perturbador das tecnologias prisionais já estabelecidas, introduzindo dissonâncias nas enunciabilidades e nas visibilidades que atravessam a prisão?

  2. Expression, purification and crystallization of the catalytic subunit of protein kinase CK2 from Zea mays

    DEFF Research Database (Denmark)

    Guerra, B; Niefind, K; Pinna, L A;

    1998-01-01

    The catalytic (alpha) subunit of protein kinase CK2 (CK2alpha) was originally cloned and overexpressed in the Escherichia coli strain pT7-7/BL21(DE3). The protein has been purified to homogeneity and crystallized. The crystals belong to the monoclinic space group C2, they have unit-cell parameters...... a = 142.6, b = 61.3, c = 45.6 A, beta = 103.3 degrees and diffract X-rays to at least 2.0 A resolution. The calculated crystal packing parameter is Vm = 2.47 A3 Da-1 suggesting that one CK2alpha molecule is contained in the asymmetric unit and that the solvent content of the unit cell is 50%....

  3. Low-density crystal packing of human protein kinase CK2 catalytic subunit in complex with resorufin or other ligands

    DEFF Research Database (Denmark)

    Klopffleisch, Karsten; Issinger, Olaf Georg; Niefind, Karsten;

    2012-01-01

    A low-resolution structure of the catalytic subunit CK2α of human protein kinase CK2 (formerly known as casein kinase 2) in complex with the ATP-competitive inhibitor resorufin is presented. The structure supplements previous human CK2α structures in which the interdomain hinge/helix αD region...

  4. Crystal structure of the catalytic subunit of protein kinase CK2 from Zea mays at 2.1 A resolution

    DEFF Research Database (Denmark)

    Niefind, K; Guerra, B; Pinna, L A;

    1998-01-01

    CK2alpha is the catalytic subunit of protein kinase CK2, an acidophilic and constitutively active eukaryotic Ser/Thr kinase involved in cell proliferation. A crystal structure, at 2.1 A resolution, of recombinant maize CK2alpha (rmCK2alpha) in the presence of ATP and Mg2+, shows the enzyme in an ...

  5. The A1 Subunit of Shiga Toxin 2 Has Higher Affinity for Ribosomes and Higher Catalytic Activity than the A1 Subunit of Shiga Toxin 1.

    Science.gov (United States)

    Basu, Debaleena; Li, Xiao-Ping; Kahn, Jennifer N; May, Kerrie L; Kahn, Peter C; Tumer, Nilgun E

    2016-01-01

    Shiga toxin (Stx)-producing Escherichia coli (STEC) infections can lead to life-threatening complications, including hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS), which is the most common cause of acute renal failure in children in the United States. Stx1 and Stx2 are AB5 toxins consisting of an enzymatically active A subunit associated with a pentamer of receptor binding B subunits. Epidemiological evidence suggests that Stx2-producing E. coli strains are more frequently associated with HUS than Stx1-producing strains. Several studies suggest that the B subunit plays a role in mediating toxicity. However, the role of the A subunits in the increased potency of Stx2 has not been fully investigated. Here, using purified A1 subunits, we show that Stx2A1 has a higher affinity for yeast and mammalian ribosomes than Stx1A1. Biacore analysis indicated that Stx2A1 has faster association and dissociation with ribosomes than Stx1A1. Analysis of ribosome depurination kinetics demonstrated that Stx2A1 depurinates yeast and mammalian ribosomes and an RNA stem-loop mimic of the sarcin/ricin loop (SRL) at a higher catalytic rate and is a more efficient enzyme than Stx1A1. Stx2A1 depurinated ribosomes at a higher level in vivo and was more cytotoxic than Stx1A1 in Saccharomyces cerevisiae. Stx2A1 depurinated ribosomes and inhibited translation at a significantly higher level than Stx1A1 in human cells. These results provide the first direct evidence that the higher affinity for ribosomes in combination with higher catalytic activity toward the SRL allows Stx2A1 to depurinate ribosomes, inhibit translation, and exhibit cytotoxicity at a significantly higher level than Stx1A1. PMID:26483409

  6. Protein kinase CK2: evidence for a protein kinase CK2beta subunit fraction, devoid of the catalytic CK2alpha subunit, in mouse brain and testicles

    DEFF Research Database (Denmark)

    Guerra, B; Siemer, S; Boldyreff, B;

    1999-01-01

    The highest CK2 activity was found in mouse testicles and brain, followed by spleen, liver, lung, kidney and heart. The activity values were directly correlated with the protein expression level of the CK2 subunits alpha (catalytic) and beta (regulatory). The alpha' subunit was only detected...... found for testicles and brain. The amount of CK2beta protein in brain in comparison to the other organs (except testicles) was estimated to be ca. 2-3-fold higher whereas the ratio of CK2beta between testicles and brain was estimated to be 3-4-fold. Results from the immunoprecipitation experiments...... support the notion for the existence of free CK2beta population and/or CK2beta in complex with other protein(s) present in brain and testicles. In all other mouse organs investigated, i.e. heart, lung, liver, kidney and spleen, no comparable amount of free CK2beta was observed. This is the first...

  7. Musashi1 Impacts Radio-Resistance in Glioblastoma by Controlling DNA-Protein Kinase Catalytic Subunit.

    Science.gov (United States)

    de Araujo, Patricia Rosa; Gorthi, Aparna; da Silva, Acarizia E; Tonapi, Sonal S; Vo, Dat T; Burns, Suzanne C; Qiao, Mei; Uren, Philip J; Yuan, Zhi-Min; Bishop, Alexander J R; Penalva, Luiz O F

    2016-09-01

    The conserved RNA-binding protein Musashi1 (MSI1) has been characterized as a stem cell marker, controlling the balance between self-renewal and differentiation and as a key oncogenic factor in numerous solid tumors, including glioblastoma. To explore the potential use of MSI1 targeting in therapy, we studied MSI1 in the context of radiation sensitivity. Knockdown of MSI1 led to a decrease in cell survival and an increase in DNA damage compared to control in cells treated with ionizing radiation. We subsequently examined mechanisms of double-strand break repair and found that loss of MSI1 reduces the frequency of nonhomologous end-joining. This phenomenon could be attributed to the decreased expression of DNA-protein kinase catalytic subunit, which we have previously identified as a target of MSI1. Collectively, our results suggest a role for MSI1 in double-strand break repair and that its inhibition may enhance the effect of radiotherapy. PMID:27470713

  8. Computational modeling of acrylodan-labeled cAMP dependent protein kinase catalytic subunit unfolding.

    Science.gov (United States)

    Kuznetsov, Aleksei; Kivi, Rait; Järv, Jaak

    2016-04-01

    Structure of the cAMP-dependent protein kinase catalytic subunit, where the asparagine residue 326 was replaced with acrylodan-cystein conjugate to implement this fluorescence reporter group into the enzyme, was modeled by molecular dynamics (MD) method and the positioning of the dye molecule in protein structure was characterized at temperatures 300K, 500K and 700K. It was found that the acrylodan moiety, which fluorescence is very sensitive to solvating properties of its microenvironment, was located on the surface of the native protein at 300K that enabled its partial solvation with water. At high temperatures the protein structure significantly changed, as the secondary and tertiary structure elements were unfolded and these changes were sensitively reflected in positioning of the dye molecule. At 700K complete unfolding of the protein occurred and the reporter group was entirely expelled into water. However, at 500K an intermediate of the protein unfolding process was formed, where the fluorescence reporter group was directed towards the protein interior and buried in the core of the formed molten globule state. This different positioning of the reporter group was in agreement with the two different shifts of emission spectrum of the covalently bound acrylodan, observed in the unfolding process of the protein. PMID:26896699

  9. Pin1 Interacts with the Epstein-Barr Virus DNA Polymerase Catalytic Subunit and Regulates Viral DNA Replication

    OpenAIRE

    Narita, Yohei; Murata, Takayuki; Ryo, Akihide; Kawashima, Daisuke; Sugimoto, Atsuko; Kanda, Teru; Kimura, Hiroshi; Tsurumi, Tatsuya

    2013-01-01

    Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) protein is known as a regulator which recognizes phosphorylated Ser/Thr-Pro motifs and increases the rate of cis and trans amide isomer interconversion, thereby altering the conformation of its substrates. We found that Pin1 knockdown using short hairpin RNA (shRNA) technology resulted in strong suppression of productive Epstein-Barr virus (EBV) DNA replication. We further identified the EBV DNA polymerase catalytic subunit, BALF5,...

  10. Docking and molecular dynamics simulations studies of human protein kinase catalytic subunit alpha with antagonist

    Directory of Open Access Journals (Sweden)

    S. Sandeep

    2012-02-01

    Full Text Available Background: Cyclic adenosine monophosphate (cAMP dependent protein kinase A plays major role in cell signalling to undergo many cellular functions. Over expression of extracellular cAMP dependent protein kinase catalytic subunit alpha (PRKACA causes severe tumorgenesis in prostate. Thus, computer aided high throughput virtual screening and molecular dynamics simulations studies were implemented to identify the potent leads for human PRKACA.Methods: The human PRKACA crystal structure was optimized in Maestro v9.2. Fifteen recently published PRKACA inhibitors were selected for compiling 5388 structural analogs from Ligand.Info database, these were pre- pared using LigPrep. Molecular docking from lesser to higher stringency towards minor steric classes was applied subsequently to the prepared ligand dataset into PRKACA active site using Glide v5.7. Molecular dynamics simulation studies were done using Desmond v3.0 to predict the activity of PRKACA-leptosidin complex.Results: Twenty lead molecules were identified. Lead-1 was observed to have relatively the least docking score compared to the identified lead molecules and 15 published inhibitors. The PRKACA- leptosidin complex deciphered that leptosidin blocked the active site residues Thr-51, Glu-121, Val- 123, Glu-127 and Thr-183 directly through intermolecular hydrogen bonds. In molecular dynamics simulations, trajectory analysis also showed existence of water bridges between PRKACA and leptosidin.Conclusions: Docking and molecular dynamics studies revealed the better binding interaction of leptosidin with PRKACA. Leptosidin is having the better pharmacological properties thus it could be a futuristic perspective chemical compound for prostate cancer therapy.

  11. Characterization of an adapter subunit to a phosphatidylinositol (3)P 3-phosphatase: Identification of a myotubularin-related protein lacking catalytic activity

    OpenAIRE

    Nandurkar, H. H.; Caldwell, K K; Whisstock, J C; Layton, M. J.; Gaudet, E. A.; Norris, F. A.; Majerus, P W; Mitchell, C. A.

    2001-01-01

    The D3-phosphoinositides act as second messengers by recruiting, and thereby activating, diverse signaling proteins. We have previously described the purification of a rat phosphatidylinositol 3-phosphate [PtdIns(3)P] 3-phosphatase, comprising a heterodimer of a 78-kDa adapter subunit in complex with a 65-kDa catalytic subunit. Here, we have cloned and characterized the cDNA encoding the human 3-phosphatase adapter subunit (3-PAP). Sequence alignment showed that 3-PAP ...

  12. Specific Residues in the Connector Loop of the Human Cytomegalovirus DNA Polymerase Accessory Protein UL44 Are Crucial for Interaction with the UL54 Catalytic Subunit

    OpenAIRE

    Loregian, Arianna; Appleton, Brent A; Hogle, James M.; Coen, Donald M.

    2004-01-01

    The human cytomegalovirus DNA polymerase includes an accessory protein, UL44, which has been proposed to act as a processivity factor for the catalytic subunit, UL54. How UL44 interacts with UL54 has not yet been elucidated. The crystal structure of UL44 revealed the presence of a connector loop analogous to that of the processivity subunit of herpes simplex virus DNA polymerase, UL42, which is crucial for interaction with its cognate catalytic subunit, UL30. To investigate the role of the UL...

  13. Overexpression of catalytic subunit M2 in patients with ovarian cancer

    Institute of Scientific and Technical Information of China (English)

    WANG Li-ming; LU Fei-fei; ZHANG Shao-yan; YAO Ru-yong; XING Xiao-ming; WEI Zhi-min

    2012-01-01

    Background The formation and growth of tumors are related to the synthesis of the DNA.The enzyme ribonucleotide reductase (RR) is an enzyme that regulates the total rate of DNA synthesis and thus plays a pivotal role in cell growth.Catalytic subunit M2 (RRM2) is the main unit modulating the ribonucleotide reductase enzymatic activity.This study aimed to investigate the expression of RRM2 mRNA and protein in patients with ovarian cancer and its relevance to diagnosis and clinical outcome of the patients.Methods RRM2 mRNA levels and protein expression were detected in 98 ovarian specimens with immunohistochemistry and real-time quantitative polymerase chain reaction (PCR).Expression of the RRM2 protein and correlation of the RRM2 gene expression with clinical pathological features were analyzed.The Kaplan-Meier test was used for evaluating RRM2 expression and time to progression and survival.The Cox proportional model was used to analyze the dsk factors in prognosis of patients.Results Positive RRM2 immunostaining was found in 43 of 62 (69.4%) patients with epithelial ovadan cancer,10 of 15 (66.7%) patients with borderline neoplasm,4 of 15 (26.7%) patients with benign growths,and none of the normal group.The RRM2 mRNA levels.were significantly over expressed in epithelial ovarian cancer (1.722±0.639) and borderline ovadan neoplasms (1.365±0.615),compared to the normal group (0.678±0.446) and benign group (0.828±0.545).Patients with ovarian caner in clinical FIGO-stages Ⅲ-Ⅳ presented higher RRM2 gene expression than those in clinical FIGO-stages Ⅰ-Ⅱ.Furthermore,the survival of patients with low RRM2 mRNA level was significantly better than patients with high levels (P <0.05).By Cox proportional risk model analysis,the risk of mortality of patients with high level expression of RRM2 mRNA was 2.553 times greater than those with low expression.Conclusion RRM2 expression closely correlates with the development of ovadan tumor and may serve as a novel

  14. Elastase-like Activity Is Dominant to Chymotrypsin-like Activity in 20S Proteasome's β5 Catalytic Subunit.

    Science.gov (United States)

    Bensinger, Dennis; Neumann, Theresa; Scholz, Christoph; Voss, Constantin; Knorr, Sabine; Kuckelkorn, Ulrike; Hamacher, Kay; Kloetzel, Peter-Michael; Schmidt, Boris

    2016-07-15

    The ubiquitin/proteasome system is the major protein degradation pathway in eukaryotes with several key catalytic cores. Targeting the β5 subunit with small-molecule inhibitors is an established therapeutic strategy for hematologic cancers. Herein, we report a mouse-trap-like conformational change that influences molecular recognition depending on the substitution pattern of a bound ligand. Variation of the size of P1 residues from the highly β5-selective proteasome inhibitor BSc2118 allows for discrimination between inhibitory strength and substrate conversion. We found that increasing molecular size strengthens inhibition, whereas decreasing P1 size accelerates substrate conversion. Evaluation of substrate hydrolysis after silencing of β5 activity reveals significant residual activity for large residues exclusively. Thus, classification of the β5 subunit as chymotrypsin-like and the use of the standard tyrosine-containing substrate should be reconsidered. PMID:27111844

  15. Autophosphorylation of the DNA-dependent protein kinase catalytic subunit is required for rejoining of DNA double-strand breaks

    OpenAIRE

    Chan, Doug W.; Chen, Benjamin Ping-Chi; Prithivirajsingh, Sheela; Kurimasa, Akihiro; Story, Michael D.; Qin, Jun; Chen, David J.

    2002-01-01

    Nonhomologous end-joining (NHEJ) is the predominant pathway that repairs DNA double-strand breaks (DSBs) in mammalian cells. The DNA-dependent protein kinase (DNA-PK), consisting of Ku and DNA-PK catalytic subunit (DNA-PKcs), is activated by DNA in vitro and is required for NHEJ. We report that DNA-PKcs is autophosphorylated at Thr2609 in vivo in a Ku-dependent manner in response to ionizing radiation. Phosphorylated DNA-PKcs colocalizes with both γ-H2AX and 53BP1 after DNA damage. Mutation o...

  16. Gene for the catalytic subunit of mouse DNA-dependent protein kinase maps to the scid locus.

    Science.gov (United States)

    Miller, R D; Hogg, J; Ozaki, J H; Gell, D; Jackson, S P; Riblet, R

    1995-01-01

    The gene encoding the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) has been proposed recently as a candidate gene for the mouse severe combined immune deficiency (scid) locus. We have used a partial cDNA clone for human DNA-PKcs to map the mouse homologue using a large interspecific backcross panel. We found that the mouse gene for DNA-PKcs does not recombine with scid, consistent with the hypothesis that scid is a mutation in the mouse gene for DNA-PKcs. Images Fig. 3 PMID:7479885

  17. [Apoptotic endonuclease EndoG induces alternative splicing of telomerase catalytic subunit hTERT and death of tumor cells].

    Science.gov (United States)

    Zhdanov, D D; Vasina, D A; Orlova, V S; Gotovtseva, V Y; Bibikova, M V; Pokrovsky, V S; Pokrovskaya, M V; Aleksandrova, S S; Sokolov, N N

    2016-03-01

    Telomerase activity is known to be regulated by alternative splicing of its catalytic subunit hTERT (human Telomerase Reverse Transcriptase) mRNA. Induction of non-active spliced hTERT leads to inhibition of telomerase activity. However, very little is known about the mechanism of hTERT mRNA alternative splicing. The aim of this study was to determine the role of apoptotic endonuclease EndoG in alternative splicing of hTERT and telomerase activity. Strong correlation was found between expression of EndoG and hTERT splice-variants in 12 colon cancer cell lines. Overexpression of EndoG in СаСо-2 cells downregulated the expression of active full-length hTERT variant and upregulated non-active spliced variant. Reduction of full-length hTERT caused downregulation of telomerase activity, dramatically shortening of telomeres length during cell divisions, converting cells to the replicative senescence state, activation of apoptosis and finally cell death. These data indicated the participation of EndoG in alternative splicing of mRNA of telomerase catalytic subunit, regulation of telomerase activity and cell fate. PMID:27420614

  18. Epidermal growth factor receptor levels are reduced in mice with targeted disruption of the protein kinase A catalytic subunit

    Directory of Open Access Journals (Sweden)

    Huitfeldt Henrik S

    2008-04-01

    Full Text Available Abstract Background Epidermal Growth Factor Receptor (EGFR is a key target molecule in current treatment of several neoplastic diseases. Hence, in order to develop and improve current drugs targeting EGFR signalling, an accurate understanding of how this signalling pathway is regulated is required. It has recently been demonstrated that inhibition of cAMP-dependent protein kinase (PKA induces a ligand-independent internalization of EGFR. Cyclic-AMP-dependent protein kinase consists of a regulatory dimer bound to two catalytic subunits. Results We have investigated the effect on EGFR levels after ablating the two catalytic subunits, Cα and Cβ in two different models. The first model used targeted disruption of either Cα or Cβ in mice whereas the second model used Cα and Cβ RNA interference in HeLa cells. In both models we observed a significant reduction of EGFR expression at the protein but not mRNA level. Conclusion Our results suggest that PKA may represent a target that when manipulated can maintain EGFR protein levels at the single cell level as well as in intact animals.

  19. 2',6'-Dihalostyrylanilines, pyridines, and pyrimidines for the inhibition of the catalytic subunit of methionine S-adenosyltransferase-2.

    Science.gov (United States)

    Sviripa, Vitaliy M; Zhang, Wen; Balia, Andrii G; Tsodikov, Oleg V; Nickell, Justin R; Gizard, Florence; Yu, Tianxin; Lee, Eun Y; Dwoskin, Linda P; Liu, Chunming; Watt, David S

    2014-07-24

    Inhibition of the catalytic subunit of the heterodimeric methionine S-adenosyl transferase-2 (MAT2A) with fluorinated N,N-dialkylaminostilbenes (FIDAS agents) offers a potential avenue for the treatment of liver and colorectal cancers where upregulation of this enzyme occurs. A study of structure-activity relationships led to the identification of the most active compounds as those with (1) either a 2,6-difluorostyryl or 2-chloro-6-fluorostyryl subunit, (2) either an N-methylamino or N,N-dimethylamino group attached in a para orientation relative to the 2,6-dihalostyryl subunit, and (3) either an N-methylaniline or a 2-(N,N-dimethylamino)pyridine ring. These modifications led to FIDAS agents that were active in the low nanomolar range, that formed water-soluble hydrochloride salts, and that possessed the desired property of not inhibiting the human hERG potassium ion channel at concentrations at which the FIDAS agents inhibit MAT2A. The active FIDAS agents may inhibit cancer cells through alterations of methylation reactions essential for cancer cell survival and growth.

  20. Conserved Residues in the Subunit Interface of tau Glutathione S-transferase Affect Catalytic and Structural Functions

    Institute of Scientific and Technical Information of China (English)

    Cai-Ling Wang; Hai-Ling Yang

    2011-01-01

    The tau class glutathione S-transferases(GSTs)have important roles in stress tolerance and the detoxification of herbicides in crops and weeds.Structural investigations of a wheat tau GST(TaGSTU4) show two subunit interactions:a hydrogen bond between the Tyr93 and Pro65 from another subunit of the dimer,and two salt bridges between residues Glu78 and side chains of Arg95 and Arg99 in the opposite subunit.By investigating enzyme activities,kinetic parameters and structural characterizations,this study showed the following results:(i)the hydrogen bond interaction between the Tyr93 and Pro65 was not essential for dimerization,but contributed to the enzyme's catalytic activity,thermal stability and affinity towards substrates glutathione and 1-chloro-2,4-dinitrobenzene;and(ii)two salt bridges mainly contributed to the protein structure stability and catalysis.The results of this study form a structural and functional basis for rational design of more selective and environmentally friendly herbicides.

  1. Crystal Structure of the Human Pol α B Subunit in Complex with the C-terminal Domain of the Catalytic Subunit.

    Science.gov (United States)

    Suwa, Yoshiaki; Gu, Jianyou; Baranovskiy, Andrey G; Babayeva, Nigar D; Pavlov, Youri I; Tahirov, Tahir H

    2015-06-01

    In eukaryotic DNA replication, short RNA-DNA hybrid primers synthesized by primase-DNA polymerase α (Prim-Pol α) are needed to start DNA replication by the replicative DNA polymerases, Pol δ and Pol ϵ. The C terminus of the Pol α catalytic subunit (p180C) in complex with the B subunit (p70) regulates the RNA priming and DNA polymerizing activities of Prim-Pol α. It tethers Pol α and primase, facilitating RNA primer handover from primase to Pol α. To understand these regulatory mechanisms and to reveal the details of human Pol α organization, we determined the crystal structure of p70 in complex with p180C. The structured portion of p70 includes a phosphodiesterase (PDE) domain and an oligonucleotide/oligosaccharide binding (OB) domain. The N-terminal domain and the linker connecting it to the PDE domain are disordered in the reported crystal structure. The p180C adopts an elongated asymmetric saddle shape, with a three-helix bundle in the middle and zinc-binding modules (Zn1 and Zn2) on each side. The extensive p180C-p70 interactions involve 20 hydrogen bonds and a number of hydrophobic interactions resulting in an extended buried surface of 4080 Å(2). Importantly, in the structure of the p180C-p70 complex with full-length p70, the residues from the N-terminal to the OB domain contribute to interactions with p180C. The comparative structural analysis revealed both the conserved features and the differences between the human and yeast Pol α complexes.

  2. Expression of the S-1 catalytic subunit of pertussis toxin in Escherichia coli.

    OpenAIRE

    Barbieri, J T; Rappuoli, R; Collier, R J

    1987-01-01

    The S-1 subunit of pertussis toxin was expressed as a fusion protein in a strain of Escherichia coli deficient in protein degradation. The fusion protein reacted with anti-pertussis toxin antibody, and, like authentic pertussis toxin, it ADP-ribosylated a 41,000-molecular-weight membrane protein from human erythrocytes.

  3. Exploring the 49-kDa subunit as part of the catalytic core of complex I (NADH:ubiquinone oxidoreductase) from Yarrowia lipolytica

    OpenAIRE

    Grgic, Ljuban

    2004-01-01

    Ligands of Iron-Sulphur Cluster N2: In this work the ubiquinone reducing catalytic core of NADH:ubiquinone oxidoreductase (complex I) from Y. lipolytica was studied by a series of point mutations replacing conserved histidines or arginines in the 49-kDa subunit. Although the missing 4th ligand of cluster N2 could not be found in the 49-kDa subunit of complex I, it was clearly demonstrated that iron-sulphur cluster N2 resides directly on the interface between the PSST and 49-kDa subunits. The ...

  4. Conformational plasticity of the catalytic subunit of protein kinase CK2 and its consequences for regulation and drug design

    DEFF Research Database (Denmark)

    Niefind, Karsten; Issinger, Olaf-Georg

    2010-01-01

    plasticity of important ATP-binding elements - the interdomain hinge region and the glycine-rich loop - was discovered. In fully active CK2alpha the hinge region is open and does not anchor the ATP ribose, but alternatively it can adopt a closed conformation, form hydrogen bonds to the ribose moiety and thus......At the first glance CK2alpha, the catalytic subunit of protein kinase CK2, is a rigid molecule: in contrast to many eukaryotic protein kinases in CK2alpha the canonical regulatory key elements like the activation segment occur exclusively in their typical active conformations. This observation fits...... well to the constitutive activity of the enzyme, meaning, its independence from phosphorylation or other characteristic control factors. Most CK2alpha structures are based on the enzyme from Zea mays, supplemented by an increasing number of human CK2alpha structures. In the latter a surprising...

  5. Human liver phosphatase 2A: cDNA and amino acid sequence of two catalytic subunit isotypes

    Energy Technology Data Exchange (ETDEWEB)

    Arino, J.; Woon, Chee Wai; Brautigan, D.L.; Miller, T.B. Jr.; Johnson, G.L. (Univ. of Massachusetts Medical School, Worcester (USA))

    1988-06-01

    Two cDNA clones were isolated from a human liver library that encode two phosphatase 2A catalytic subunits. The two cDNAs differed in eight amino acids (97% identity) with three nonconservative substitutions. All of the amino acid substitutions were clustered in the amino-terminal domain of the protein. Amino acid sequence of one human liver clone (HL-14) was identical to the rabbit skeletal muscle phosphatase 2A cDNA (with 97% nucleotide identity). The second human liver clone (HL-1) is encoded by a separate gene, and RNA gel blot analysis indicates that both mRNAs are expressed similarly in several human clonal cell lines. Sequence comparison with phosphatase 1 and 2A indicates highly divergent amino acid sequences at the amino and carboxyl termini of the proteins and identifies six highly conserved regions between the two proteins that are predicted to be important for phosphatase enzymatic activity.

  6. Expression of Recombinant Chinese Bovine Enterokinase Catalytic Subunit in P.pastoris and Its Purification and Characterization

    Institute of Scientific and Technical Information of China (English)

    Lei FANG; Qi-Ming SUN; Zi-Chun HUA

    2004-01-01

    Enterokinase is a tool protease widely utilized in the cleavage of recombinant fusion proteins.cDNA encoding the catalytic subunit of Chinese bovine enterokinase (EKL) was amplified by PCR and then to get the α-MF signal-EKL-His6 encoding gene by PCR. Then the whole coding sequence was cloned into the integrative plasmid pAO815 under the control of a methanol-inducible promoter and transformed GS 115methylotrophic strain of Pichiapastoris. Secreted expression of recombinant EKL-His6 was attained by methanol induction and its molecular weight is 43 kD. Because of the existence of His6-tag, EKL-His6 was easily purified from P. pastoris fermentation supernatant by using Ni2+ affinity chromatography and the yield is 5.4 mg per liter of fermentation culture. This purified EKL-His6 demonstrates excellent cleavage activity towards fusion protein containing EK cleavage site.

  7. Human intestinal maltase-glucoamylase: crystal structure of the N-terminal catalytic subunit and basis of inhibition and substrate specificity

    Science.gov (United States)

    Human maltase-glucoamylase (MGAM) is one of the two enzymes responsible for catalyzing the last glucose-releasing step in starch digestion. MGAM is anchored to the small-intestinal brush-border epithelial cells and contains two homologous glycosyl hydrolase family 31 catalytic subunits: an N-termina...

  8. Structure of a catalytic dimer of the α- and β-subunits of the F-ATPase from Paracoccus denitrificans at 2.3 Å resolution

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Ríos, Edgar; Montgomery, Martin G. [The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY (United Kingdom); Leslie, Andrew G. W. [The Medical Research Council Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom); García-Trejo, José J. [Universidad Nacional Autónoma de México, Mexico City (Mexico); Walker, John E., E-mail: walker@mrc-mbu.cam.ac.uk [The Medical Research Council Mitochondrial Biology Unit, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY (United Kingdom)

    2015-09-23

    The structure of the αβ heterodimer of the F-ATPase from the α-proteobacterium P. denitrificans has been determined at 2.3 Å resolution. It corresponds to the ‘open’ or ‘empty’ catalytic interface found in other F-ATPases. The structures of F-ATPases have predominantly been determined from mitochondrial enzymes, and those of the enzymes in eubacteria have been less studied. Paracoccus denitrificans is a member of the α-proteobacteria and is related to the extinct protomitochondrion that became engulfed by the ancestor of eukaryotic cells. The P. denitrificans F-ATPase is an example of a eubacterial F-ATPase that can carry out ATP synthesis only, whereas many others can catalyse both the synthesis and the hydrolysis of ATP. Inhibition of the ATP hydrolytic activity of the P. denitrificans F-ATPase involves the ζ inhibitor protein, an α-helical protein that binds to the catalytic F{sub 1} domain of the enzyme. This domain is a complex of three α-subunits and three β-subunits, and one copy of each of the γ-, δ- and ∊-subunits. Attempts to crystallize the F{sub 1}–ζ inhibitor complex yielded crystals of a subcomplex of the catalytic domain containing the α- and β-subunits only. Its structure was determined to 2.3 Å resolution and consists of a heterodimer of one α-subunit and one β-subunit. It has no bound nucleotides, and it corresponds to the ‘open’ or ‘empty’ catalytic interface found in other F-ATPases. The main significance of this structure is that it aids in the determination of the structure of the intact membrane-bound F-ATPase, which has been crystallized.

  9. Structure of a catalytic dimer of the α- and β-subunits of the F-ATPase from Paracoccus denitrificans at 2.3 Å resolution

    International Nuclear Information System (INIS)

    The structure of the αβ heterodimer of the F-ATPase from the α-proteobacterium P. denitrificans has been determined at 2.3 Å resolution. It corresponds to the ‘open’ or ‘empty’ catalytic interface found in other F-ATPases. The structures of F-ATPases have predominantly been determined from mitochondrial enzymes, and those of the enzymes in eubacteria have been less studied. Paracoccus denitrificans is a member of the α-proteobacteria and is related to the extinct protomitochondrion that became engulfed by the ancestor of eukaryotic cells. The P. denitrificans F-ATPase is an example of a eubacterial F-ATPase that can carry out ATP synthesis only, whereas many others can catalyse both the synthesis and the hydrolysis of ATP. Inhibition of the ATP hydrolytic activity of the P. denitrificans F-ATPase involves the ζ inhibitor protein, an α-helical protein that binds to the catalytic F1 domain of the enzyme. This domain is a complex of three α-subunits and three β-subunits, and one copy of each of the γ-, δ- and ∊-subunits. Attempts to crystallize the F1–ζ inhibitor complex yielded crystals of a subcomplex of the catalytic domain containing the α- and β-subunits only. Its structure was determined to 2.3 Å resolution and consists of a heterodimer of one α-subunit and one β-subunit. It has no bound nucleotides, and it corresponds to the ‘open’ or ‘empty’ catalytic interface found in other F-ATPases. The main significance of this structure is that it aids in the determination of the structure of the intact membrane-bound F-ATPase, which has been crystallized

  10. A Single Conserved Residue Mediates Binding of the Ribonucleotide Reductase Catalytic Subunit RRM1 to RRM2 and Is Essential for Mouse Development

    DEFF Research Database (Denmark)

    Specks, Julia; Lecona, Emilio; Lopez-Contreras, Andres J.;

    2015-01-01

    The ribonucleotide reductase (RNR) complex, composed of a catalytic subunit (RRM1) and a regulatory subunit (RRM2), is thought to be a rate-limiting enzymatic complex for the production of nucleotides. In humans, the Rrm1 gene lies at 11p15.5, a tumor suppressor region, and RRM1 expression in......, despite being viable, leads to increased interaction of the RNR complex with its allosteric inhibitor Sml1. In contrast to yeast, homozygous mutant mice carrying the Rrm1 mutation (Rrm1WG/WG) are not viable, even at the earliest embryonic stages. Proteomic analyses failed to identify proteins that...

  11. The Catalytic Subunit of DNA-Dependent Protein Kinase Coordinates with Polo-Like Kinase 1 to Facilitate Mitotic Entry

    Directory of Open Access Journals (Sweden)

    Kyung-Jong Lee

    2015-04-01

    Full Text Available DNA-dependent protein kinase catalytic subunit (DNA-PKcs is the key regulator of the non-homologous end joining pathway of DNA double-strand break repair. We have previously reported that DNA-PKcs is required for maintaining chromosomal stability and mitosis progression. Our further investigations reveal that deficiency in DNA-PKcs activity caused a delay in mitotic entry due to dysregulation of cyclin-dependent kinase 1 (Cdk1, the key driving force for cell cycle progression through G2/M transition. Timely activation of Cdk1 requires polo-like kinase 1 (Plk1, which affects modulators of Cdk1. We found that DNA-PKcs physically interacts with Plk1 and could facilitate Plk1 activation both in vitro and in vivo. Further, DNA-PKcs–deficient cells are highly sensitive to Plk1 inhibitor BI2536, suggesting that the coordination between DNA-PKcs and Plk1 is not only crucial to ensure normal cell cycle progression through G2/M phases but also required for cellular resistance to mitotic stress. On the basis of the current study, it is predictable that combined inhibition of DNA-PKcs and Plk1 can be employed in cancer therapy strategy for synthetic lethality.

  12. The Catalytic Subunit of DNA-Dependent Protein Kinase Coordinates with Polo-Like Kinase 1 to Facilitate Mitotic Entry.

    Science.gov (United States)

    Lee, Kyung-Jong; Shang, Zeng-Fu; Lin, Yu-Fen; Sun, Jingxin; Morotomi-Yano, Keiko; Saha, Debabrata; Chen, Benjamin P C

    2015-04-01

    DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is the key regulator of the non-homologous end joining pathway of DNA double-strand break repair. We have previously reported that DNA-PKcs is required for maintaining chromosomal stability and mitosis progression. Our further investigations reveal that deficiency in DNA-PKcs activity caused a delay in mitotic entry due to dysregulation of cyclin-dependent kinase 1 (Cdk1), the key driving force for cell cycle progression through G2/M transition. Timely activation of Cdk1 requires polo-like kinase 1 (Plk1), which affects modulators of Cdk1. We found that DNA-PKcs physically interacts with Plk1 and could facilitate Plk1 activation both in vitro and in vivo. Further, DNA-PKcs-deficient cells are highly sensitive to Plk1 inhibitor BI2536, suggesting that the coordination between DNA-PKcs and Plk1 is not only crucial to ensure normal cell cycle progression through G2/M phases but also required for cellular resistance to mitotic stress. On the basis of the current study, it is predictable that combined inhibition of DNA-PKcs and Plk1 can be employed in cancer therapy strategy for synthetic lethality.

  13. A model of 3D-structure of H+,K+-ATPase catalytic subunit derived by homology modeling

    Institute of Scientific and Technical Information of China (English)

    Dong YAN; Yuan-dong HU; Song LI; Mao-sheng CHENG

    2004-01-01

    AIM: To build a model of 3D-structure of H+, K+-ATPase catalytic subunit for theoretical study and anti-ulcer drug design. METHODS: The model was built on the basis of structural data from the Ca2+-ATPase. Structurally conserved regions were defined by amino acid sequence comparisons, optimum interconnecting loops were selected from the protein databank, and amino (N)- and carboxyl (C)-terminal ends were generated as random coil structures. Applying molecular mechanics method then minimized the model energy. Molecular dynamics technique was used to do further structural optimization. RESULTS: The model of 3D-structure of H+, K+-ATPase was derived. The model is reasonable according to several validation criteria. There were ten transmembrane helices (TM1-TM 10) in the model and inhibitor-binding site was identified on the TM5-8 riched negatively charged residues.CONCLUSION: The 3D-structure model from our study is informative to guide future molecular biology study about H+, K+-ATPase and drug design based on database searching.

  14. Studies of mice with cyclic AMP-dependent protein kinase (PKA) defects reveal the critical role of PKA's catalytic subunits in anxiety.

    Science.gov (United States)

    Briassoulis, George; Keil, Margaret F; Naved, Bilal; Liu, Sophie; Starost, Matthew F; Nesterova, Maria; Gokarn, Nirmal; Batistatos, Anna; Wu, T John; Stratakis, Constantine A

    2016-07-01

    Cyclic adenosine mono-phosphate-dependent protein kinase (PKA) is critically involved in the regulation of behavioral responses. Previous studies showed that PKA's main regulatory subunit, R1α, is involved in anxiety-like behaviors. The purpose of this study was to determine how the catalytic subunit, Cα, might affect R1α's function and determine its effects on anxiety-related behaviors. The marble bury (MB) and elevated plus maze (EPM) tests were used to assess anxiety-like behavior and the hotplate test to assess nociception in wild type (WT) mouse, a Prkar1a heterozygote (Prkar1a(+/-)) mouse with haploinsufficiency for the regulatory subunit (R1α), a Prkaca heterozygote (Prkaca(+/-)) mouse with haploinsufficiency for the catalytic subunit (Cα), and a double heterozygote mouse (Prkar1a(+/-)/Prkaca(+/-)) with haploinsufficiency for both R1α and Cα. We then examined specific brain nuclei involved in anxiety. Results of MB test showed a genotype effect, with increased anxiety-like behavior in Prkar1a(+/-) and Prkar1a(+/-)/Prkaca(+/-) compared to WT mice. In the EPM, Prkar1a(+/-) spent significantly less time in the open arms, while Prkaca(+/-) and Prkar1a(+/-)/Prkaca(+/-) mice displayed less exploratory behavior compared to WT mice. The loss of one Prkar1a allele was associated with a significant increase in PKA activity in the basolateral (BLA) and central (CeA) amygdala and ventromedial hypothalamus (VMH) in both Prkar1a(+/-) and Prkar1a(+/-)/Prkaca(+/-) mice. Alterations of PKA activity induced by haploinsufficiency of its main regulatory or most important catalytic subunits result in anxiety-like behaviors. The BLA, CeA, and VMH are implicated in mediating these PKA effects in brain. PMID:26992826

  15. PRIS-STATISTICS: Power Reactor Information System Statistical Reports. User's Manual

    International Nuclear Information System (INIS)

    The IAEA developed the Power Reactor Information System (PRIS)-Statistics application to assist PRIS end users with generating statistical reports from PRIS data. Statistical reports provide an overview of the status, specification and performance results of every nuclear power reactor in the world. This user's manual was prepared to facilitate the use of the PRIS-Statistics application and to provide guidelines and detailed information for each report in the application. Statistical reports support analyses of nuclear power development and strategies, and the evaluation of nuclear power plant performance. The PRIS database can be used for comprehensive trend analyses and benchmarking against best performers and industrial standards.

  16. The Over-expression of the β2 Catalytic Subunit of the Proteasome Decreases Homologous Recombination and Impairs DNA Double-Strand Break Repair in Human Cells

    Directory of Open Access Journals (Sweden)

    Anita Collavoli

    2011-01-01

    Full Text Available By a human cDNA library screening, we have previously identified two sequences coding two different catalytic subunits of the proteasome which increase homologous recombination (HR when overexpressed in the yeast Saccharomyces cerevisiae. Here, we investigated the effect of proteasome on spontaneous HR and DNA repair in human cells. To determine if the proteasome has a role in the occurrence of spontaneous HR in human cells, we overexpressed the β2 subunit of the proteasome in HeLa cells and determined the effect on intrachromosomal HR. Results showed that the overexpression of β2 subunit decreased HR in human cells without altering the cell proteasome activity and the Rad51p level. Moreover, exposure to MG132 that inhibits the proteasome activity reduced HR in human cells. We also found that the expression of the β2 subunit increases the sensitivity to the camptothecin that induces DNA double-strand break (DSB. This suggests that the β2 subunit has an active role in HR and DSB repair but does not alter the intracellular level of the Rad51p.

  17. Uncovering the stoichiometry of Pyrococcus furiosus RNase P, a multi-subunit catalytic ribonucleoprotein complex, by surface-induced dissociation and ion mobility mass spectrometry.

    Science.gov (United States)

    Ma, Xin; Lai, Lien B; Lai, Stella M; Tanimoto, Akiko; Foster, Mark P; Wysocki, Vicki H; Gopalan, Venkat

    2014-10-20

    We demonstrate that surface-induced dissociation (SID) coupled with ion mobility mass spectrometry (IM-MS) is a powerful tool for determining the stoichiometry of a multi-subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg(2+). We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5' maturation. Previous step-wise, Mg(2+)-dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21⋅RPP29 and POP5⋅RPP30) revealed functional RNP intermediates en route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21⋅RPP29 and (POP5⋅RPP30)2 complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM-MS in resolving conformational heterogeneity and yielding insights on RNP assembly.

  18. The prokaryote-to-eukaryote transition reflected in the evolution of the V/F/A-ATPase catalytic and proteolipid subunits

    Science.gov (United States)

    Hilario, E.; Gogarten, J. P.

    1998-01-01

    Changes in the primary and quarternary structure of vacuolar and archaeal type ATPases that accompany the prokaryote-to-eukaryote transition are analyzed. The gene encoding the vacuolar-type proteolipid of the V-ATPase from Giardia lamblia is reported. Giardia has a typical vacuolar ATPase as observed from the common motifs shared between its proteolipid subunit and other eukaryotic vacuolar ATPases, suggesting that the former enzyme works as a hydrolase in this primitive eukaryote. The phylogenetic analyses of the V-ATPase catalytic subunit and the front and back halves of the proteolipid subunit placed Giardia as the deepest branch within the eukaryotes. Our phylogenetic analysis indicated that at least two independent duplication and fusion events gave rise to the larger proteolipid type found in eukaryotes and in Methanococcus. The spatial distribution of the conserved residues among the vacuolar-type proteolipids suggest a zipper-type interaction among the transmembrane helices and surrounding subunits of the V-ATPase complex. Important residues involved in the function of the F-ATP synthase proteolipid have been replaced during evolution in the V-proteolipid, but in some cases retained in the archaeal A-ATPase. Their possible implication in the evolution of V/F/A-ATPases is discussed.

  19. Cryoelectron Microscopy Structure of the DNA-dependent Protein Kinase Catalytic Subunit (DNA-PKcs) at Subnanometer Resolution Reveals α-Helices and Insight into DNA Binding

    OpenAIRE

    Williams, Dewight R.; Lee, Kyung-Jong; Shi, Jian; Chen, David J.; Stewart, Phoebe L

    2008-01-01

    The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) regulates the non-homologous end joining pathway for repair of double-stranded DNA breaks. Here we present a 7Å resolution structure of DNA-PKcs determined by cryoEM single particle reconstruction. This structure is composed of density rods throughout the molecule indicative of α-helices and reveals new structural features not observed in lower resolution EM structures. Docking of homology models into the DNA-PKcs structure demonst...

  20. Residues of Human Cytomegalovirus DNA Polymerase Catalytic Subunit UL54 That Are Necessary and Sufficient for Interaction with the Accessory Protein UL44

    OpenAIRE

    Loregian, Arianna; Appleton, Brent A; Hogle, James M.; Coen, Donald M.

    2004-01-01

    The human cytomegalovirus DNA polymerase contains a catalytic subunit, UL54, and an accessory protein, UL44. Recent studies suggested that UL54 might interact via its extreme C terminus with UL44 (A. Loregian, R. Rigatti, M. Murphy, E. Schievano, G. Palu', and H. S. Marsden, J. Virol. 77:8336-8344, 2003). To address this hypothesis, we quantitatively measured the binding of peptides corresponding to the extreme C terminus of UL54 to UL44 by using isothermal titration calorimetry. A peptide co...

  1. Elevated breast cancer risk in irradiated BALB/c mice associates with unique functional polymorphism of the Prkdc (DNA-dependent protein kinase catalytic subunit) gene

    Science.gov (United States)

    Yu, Y.; Okayasu, R.; Weil, M. M.; Silver, A.; McCarthy, M.; Zabriskie, R.; Long, S.; Cox, R.; Ullrich, R. L.

    2001-01-01

    Female BALB/c mice are unusually radiosensitive and more susceptible than C57BL/6 and other tested inbred mice to ionizing radiation (IR)-induced mammary tumors. This breast cancer susceptibility is correlated with elevated susceptibility for mammary cell transformation and genomic instability following irradiation. In this study, we report the identification of two BALB/c strain-specific polymorphisms in the coding region of Prkdc, the gene encoding the DNA-dependent protein kinase catalytic subunit, which is known to be involved in DNA double-stranded break repair and post-IR signal transduction. First, we identified an A --> G transition at base 11530 resulting in a Met --> Val conversion at codon 3844 (M3844V) in the phosphatidylinositol 3-kinase domain upstream of the scid mutation (Y4046X). Second, we identified a C --> T transition at base 6418 resulting in an Arg --> Cys conversion at codon 2140 (R2140C) downstream of the putative leucine zipper domain. This unique PrkdcBALB variant gene is shown to be associated with decreased DNA-dependent protein kinase catalytic subunit activity and with increased susceptibility to IR-induced genomic instability in primary mammary epithelial cells. The data provide the first evidence that naturally arising allelic variation in a mouse DNA damage response gene may associate with IR response and breast cancer risk.

  2. Structure of the human protein kinase CK2 catalytic subunit CK2α' and interaction thermodynamics with the regulatory subunit CK2β

    DEFF Research Database (Denmark)

    Bischoff, Nils; Olsen, Birgitte; Raaf, Jennifer;

    2011-01-01

    the limited biochemical knowledge about the second paralog (CK2α'), we developed a well-soluble catalytically active full-length mutant of human CK2α', characterized it by Michaelis-Menten kinetics and isothermal titration calorimetry, and determined its crystal structure to a resolution of 2 Å. The affinity...... in CK2α' is stabilized by two elements that are absent in CK2α: (1) the extension of the N-terminal β-sheet by an additional β-strand, and (2) the filling of a conserved hydrophobic cavity between the β4/β5 loop and helix αC by a tryptophan residue. Moreover, the interdomain hinge region of CK2α' adopts...... a fully functional conformation, while unbound CK2α is often found with a nonproductive hinge conformation that is overcome only by CK2β binding. Taken together, CK2α' exhibits a significantly lower affinity for CK2β than CK2α; moreover, in functionally critical regions, it is less dependent on CK2β...

  3. Functional intersection of ATM and DNA-dependent protein kinase catalytic subunit in coding end joining during V(D)J recombination

    DEFF Research Database (Denmark)

    Lee, Baeck-Seung; Gapud, Eric J; Zhang, Shichuan;

    2013-01-01

    V(D)J recombination is initiated by the RAG endonuclease, which introduces DNA double-strand breaks (DSBs) at the border between two recombining gene segments, generating two hairpin-sealed coding ends and two blunt signal ends. ATM and DNA-dependent protein kinase catalytic subunit (DNA......-PKcs deficiency leads to a nearly complete block in coding join formation, as DNA-PKcs is required to activate Artemis, the endonuclease that opens hairpin-sealed coding ends. In contrast to loss of DNA-PKcs protein, here we show that inhibition of DNA-PKcs kinase activity has no effect on coding join formation......-PKcs) are serine-threonine kinases that orchestrate the cellular responses to DNA DSBs. During V(D)J recombination, ATM and DNA-PKcs have unique functions in the repair of coding DNA ends. ATM deficiency leads to instability of postcleavage complexes and the loss of coding ends from these complexes. DNA...

  4. Cloning and sequence analysis of a full-length cDNA of SmPP1cb encoding turbot protein phosphatase 1 beta catalytic subunit

    Science.gov (United States)

    Qi, Fei; Guo, Huarong; Wang, Jian

    2008-02-01

    Reversible protein phosphorylation, catalyzed by protein kinases and phosphatases, is an important and versatile mechanism by which eukaryotic cells regulate almost all the signaling processes. Protein phosphatase 1 (PP1) is the first and well-characterized member of the protein serine/threonine phosphatase family. In the present study, a full-length cDNA encoding the beta isoform of the catalytic subunit of protein phosphatase 1(PP1cb), was for the first time isolated and sequenced from the skin tissue of flatfish turbot Scophthalmus maximus, designated SmPP1cb, by the rapid amplification of cDNA ends (RACE) technique. The cDNA sequence of SmPP1cb we obtained contains a 984 bp open reading frame (ORF), flanked by a complete 39 bp 5' untranslated region and 462 bp 3' untranslated region. The ORF encodes a putative 327 amino acid protein, and the N-terminal section of this protein is highly acidic, Met-Ala-Glu-Gly-Glu-Leu-Asp-Val-Asp, a common feature for PP1 catalytic subunit but absent in protein phosphatase 2B (PP2B). And its calculated molecular mass is 37 193 Da and pI 5.8. Sequence analysis indicated that, SmPP1cb is extremely conserved in both amino acid and nucleotide acid levels compared with the PP1cb of other vertebrates and invertebrates, and its Kozak motif contained in the 5'UTR around ATG start codon is GXXAXXGXX ATGG, which is different from mammalian in two positions A-6 and G-3, indicating the possibility of different initiation of translation in turbot, and also the 3'UTR of SmPP1cb is highly diverse in the sequence similarity and length compared with other animals, especially zebrafish. The cloning and sequencing of SmPP1cb gene lays a good foundation for the future work on the biological functions of PP1 in the flatfish turbot.

  5. Structural bases of dimerization of yeast telomere protein Cdc13 and its interaction with the catalytic subunit of DNA polymerase α

    Institute of Scientific and Technical Information of China (English)

    Jia Sun; Neal F Lue; Ming Lei; Yuting Yang; Ke Wan; Ninghui Mao; Tai-Yuan Yu; Yi-Chien Lin; Diane C DeZwaan; Brian C Freeman; Jing-Jer Lin

    2011-01-01

    Budding yeast Cdc13-Stnl-Tenl (CST) complex plays an essential role in telomere protection and maintenance, and has been proposed to be a telomere-specific replication protein A (RPA)-like complex. Previous genetic and structural studies revealed a close resemblance between Stn1-Ten1 and RPA32-RPA14. However, the relationship between Cdc13 and RPA70, the largest subunit of RPA, has remained unclear. Here, we report the crystal structure of the N-terminal OB (oligonucleotide/oligosaccharide binding) fold of Cdc13. Although Cdc13 has an RPA70-like domain organization, the structures of Cdc13 OB folds are significantly different from their counterparts in RPA70, suggesting that they have distinct evolutionary origins. Furthermore, our structural and biochemical analyses revealed unexpected dimerization by the N-terminal OB fold and showed that homodimerization is probably a conserved feature of all Cdc13 proteins. We also uncovered the structural basis of the interaction between the Cdc13 N-terminal OB ' fold and the catalytic subunit of DNA polymerase a (Pol1), and demonstrated a role for Cdc13 dimerization in Pol1 binding. Analysis of the phenotypes of mutants defective in Cdc13 dimerization and Cdc13-Pol1 interaction revealed multiple mechanisms by which dimerization regulates telomere lengths in vivo. Collectively, our findings provide novel insights into the mechanisms and evolution of Cdc13.

  6. Cloning and sequence analysis of a full-length cDNA of SmPP1cb encoding turbot protein phosphatase 1 beta catalytic subunit

    Institute of Scientific and Technical Information of China (English)

    QI Fei; GUO Huarong; WANG Jian

    2008-01-01

    Reversible protein phosphorylation,catalyzed by protein kinases and phosphatases,is an important and versatile mechanism by which eukaryotic cells regulate almost all the signaling processes.Protein phosphatase 1(PP1) is the first and well-characterized member of the protein serine/threoninephosphatase family.In the present study.a full-length cDNA encoding the beta isolorm of the catalytic subunit of protein phosphatase 1(PP1cb).was for the first time isolated and sequenced from the skin tissue of flatfish turbot Scophthalmus maximus,designated SmPP1cb,by the rapid amplification of cDNA ends (RACE) technique.The cDNA sequence of SmPP1cb we obtained contains a 984 bp open reading frame(ORF),flanked by a complete 39 bp 5' untranslated region and 462 bp 3' untranslated region.The ORF encodes a putative 327 amino acid protein.and the N-terminal section of this protein iS highly acidic,Met-Ala-Glu-Gly-Glu-Leu-Asp-Val-Asp.a common feature for PP1 catalytic subunit but absent in protein phosphatase 2B(PP2B).And its calculated molecular mass is 37 193 Da and pI 5.8.Sequence analysis indicated that,SmPP1cb is extremely conserved in both amino acid and nucleotide acid levels compared with the PP1cb of other vertebrates and invertebrates.and its Kozak motif contained in the 5'UTR around ATG start codon is GXXAXXGXXATGG,which is different from mammalian in two positions A-6 and G-3,indicating the possibility of different initiation of translation in turbot,and also the 3'UTR of SmPP1cb is highly diverse in the sequence similarity and length compared with other animals.especially zebrafish.The cloning and sequencing of SmPP1cb gene lays a good foundation for the future work on the biological functions of PP1 in the flatfish turbot.

  7. Mapping the Hydrogen Bond Networks in the Catalytic Subunit of Protein Kinase A Using H/D Fractionation Factors.

    Science.gov (United States)

    Li, Geoffrey C; Srivastava, Atul K; Kim, Jonggul; Taylor, Susan S; Veglia, Gianluigi

    2015-07-01

    Protein kinase A is a prototypical phosphoryl transferase, sharing its catalytic core (PKA-C) with the entire kinase family. PKA-C substrate recognition, active site organization, and product release depend on the enzyme's conformational transitions from the open to the closed state, which regulate its allosteric cooperativity. Here, we used equilibrium nuclear magnetic resonance hydrogen/deuterium (H/D) fractionation factors (φ) to probe the changes in the strength of hydrogen bonds within the kinase upon binding the nucleotide and a pseudosubstrate peptide (PKI5-24). We found that the φ values decrease upon binding both ligands, suggesting that the overall hydrogen bond networks in both the small and large lobes of PKA-C become stronger. However, we observed several important exceptions, with residues displaying higher φ values upon ligand binding. Notably, the changes in φ values are not localized near the ligand binding pockets; rather, they are radiated throughout the entire enzyme. We conclude that, upon ligand and pseudosubstrate binding, the hydrogen bond networks undergo extensive reorganization, revealing that the open-to-closed transitions require global rearrangements of the internal forces that stabilize the enzyme's fold. PMID:26030372

  8. Association between the PPP3CC gene, coding for the calcineurin gamma catalytic subunit, and bipolar disorder

    Directory of Open Access Journals (Sweden)

    Bellivier Frank

    2008-01-01

    Full Text Available Abstract Background Calcineurin is a neuron-enriched phosphatase that regulates synaptic plasticity and neuronal adaptation. Activation of calcineurin, overall, antagonizes the effects of the cyclic AMP activated protein/kinase A. Thus, kinase/phosphatase dynamic balance seems to be critical for transition to long-term cellular responses in neurons, and disruption of this equilibrium should induce behavioral impairments in animal models. Genetic animal models, as well as post-mortem studies in humans have implicated calcineurin dependent calcium and cyclic AMP regulated phosphorylation/dephosphorylation in both affective responses and psychosis. Recently, genetic association between schizophrenia and genetic variation of the human calcineurin A gamma subunit gene (PPP3CC has been reported. Methods Based on the assumption of the common underlying genetic factor in schizophrenia and bipolar affective disorder (BPAD, we performed association analysis of CC33 and CCS3 polymorphisms of the PPP3CC gene reported to be associated with schizophrenia in a French sample of 115 BPAD patients and 97 healthy controls. Results Carrying 'CT' or 'TT' genotypes of the PPP3CC-CC33 polymorphism increased risk to develop BPAD comparing to carry 'CC' genotype (OR = 1.8 [1.01–3.0]; p = 0.05. For the PPP3CC-CCS3 polymorphism, 'AG' or 'GG' carriers have an increased risk to develop BPAD than 'AA' carriers (OR = 2.8 [1.5–5.2]. The CC33 and CCS3 polymorphisms were observed in significant linkage disequilibrium (D' = 0.91, r2 = 0.72. Haplotype frequencies were significantly different in BPAD patients than in controls (p = 0.03, with a significant over-transmission of the 'TG' haplotype in BPAD patients (p = 0.001. Conclusion: We suggest that the PPP3CC gene might be a susceptibility gene for BPAD, in accordance with current neurobiological hypotheses that implicate dysregulation of signal-transduction pathways, such as those regulated by calcineurin, in the etiology of

  9. Protein Phosphatase 2A Catalytic Subunit α Plays a MyD88-Dependent, Central Role in the Gene-Specific Regulation of Endotoxin Tolerance

    Directory of Open Access Journals (Sweden)

    Ling Xie

    2013-03-01

    Full Text Available MyD88, the intracellular adaptor of most TLRs, mediates either proinflammatory or immunosuppressive signaling that contributes to chronic inflammation-associated diseases. Although gene-specific chromatin modifications regulate inflammation, the role of MyD88 signaling in establishing such epigenetic landscapes under different inflammatory states remains elusive. Using quantitative proteomics to enumerate the inflammation-phenotypic constituents of the MyD88 interactome, we found that in endotoxin-tolerant macrophages, protein phosphatase 2A catalytic subunit α (PP2Ac enhances its association with MyD88 and is constitutively activated. Knockdown of PP2Ac prevents suppression of proinflammatory genes and resistance to apoptosis. Through site-specific dephosphorylation, constitutively active PP2Ac disrupts the signal-promoting TLR4-MyD88 complex and broadly suppresses the activities of multiple proinflammatory/proapoptotic pathways as well, shifting proinflammatory MyD88 signaling to a prosurvival mode. Constitutively active PP2Ac translocated with MyD88 into the nuclei of tolerant macrophages establishes the immunosuppressive pattern of chromatin modifications and represses chromatin remodeling to selectively silence proinflammatory genes, coordinating the MyD88-dependent inflammation control at both signaling and epigenetic levels under endotoxin-tolerant conditions.

  10. Identification of a nonsense mutation in the carboxyl-terminal region of DNA-dependent protein kinase catalytic subunit in the scid mouse.

    Science.gov (United States)

    Blunt, T; Gell, D; Fox, M; Taccioli, G E; Lehmann, A R; Jackson, S P; Jeggo, P A

    1996-01-01

    DNA-dependent protein kinase (DNA-PK) consists of a heterodimeric protein (Ku) and a large catalytic subunit (DNA-PKcs). The Ku protein has double-stranded DNA end-binding activity that serves to recruit the complex to DNA ends. Despite having serine/threonine protein kinase activity, DNA-PKcs falls into the phosphatidylinositol 3-kinase superfamily. DNA-PK functions in DNA double-strand break repair and V(D)J recombination, and recent evidence has shown that mouse scid cells are defective in DNA-PKcs. In this study we have cloned the cDNA for the carboxyl-terminal region of DNA-PKcs in rodent cells and identified the existence of two differently spliced products in human cells. We show that DNA-PKcs maps to the same chromosomal region as the mouse scid gene. scid cells contain approximately wild-type levels of DNA-PKcs transcripts, whereas the V-3 cell line, which is also defective in DNA-PKcs, contains very reduced transcript levels. Sequence comparison of the carboxyl-terminal region of scid and wild-type mouse cells enabled us to identify a nonsense mutation within a highly conserved region of the gene in mouse scid cells. This represents a strong candidate for the inactivating mutation in DNA-PKcs in the scid mouse. Images Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8816792

  11. Molecular Cloning, Structural Analysis and Tissue Expression of Protein Phosphatase 3 Catalytic Subunit Alpha Isoform (PPP3CA Gene in Tianfu Goat Muscle

    Directory of Open Access Journals (Sweden)

    Lu Wan

    2014-02-01

    Full Text Available Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, plays a critical role in controlling skeletal muscle fiber type. However, little information is available concerning the expression of calcineurin in goat. Therefore, protein phosphatase 3 catalytic subunit alpha isoform (PPP3CA gene, also called calcineurin Aα, was cloned and its expression characterized in Tianfu goat muscle. Real time quantitative polymerase chain reaction (RT-qPCR analyses revealed that Tianfu goat PPP3CA was detected in cardiac muscle, biceps femoris muscle, abdominal muscle, longissimus dors muscle, and soleus muscle. High expression levels were found in biceps femoris muscle, longissimus muscle and abdominal muscle (p < 0.01, and low expression levels were seen in cardiac muscle and soleus muscle (p > 0.05. In addition, the spatial-temporal mRNA expression levels showed different variation trends in different muscles with the age of the goats. Western blotting further revealed that PPP3CA protein was expressed in the above-mentioned tissues, with the highest level in biceps femoris muscle, and the lowest level in soleus muscle. In this study, we isolated the full-length coding sequence of Tianfu goat PPP3CA gene, analyzed its structure, and investigated its expression in different muscle tissues from different age stages. These results provide a foundation for understanding the function of the PPP3CA gene in goats.

  12. Inhibition of CK2 Activity by TCDD via Binding to ATP-competitive Binding Site of Catalytic Subunit:Insight from Computational Studies

    Institute of Scientific and Technical Information of China (English)

    XU Xian-jin; CANNISTRARO Salvatore; BIZZARRI Anna-rita; ZENG Yi; CHEN Wei-zu; WANG Cun-xin

    2013-01-01

    Alternative mechanisms of toxic effects induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD),instead of the binding to aryl hydrocarbon receptor(AhR),have been taken into consideration.It has been recently shown that TCDD reduces rapidly the activity of CK2(casein kinase Ⅱ) both in vivo and in vitro.It is found that TCDD has high molecular similarities to the known inhibitors of CK2 catalytic subunit(CK2α).This suggests that TCDD could also be an ATP-competitive inhibitor of CK2α.In this work,docking TCDD to CK2 was carried out based on the two structures of CK2α from maize and human,respectively.The binding free energies of the predicted CK2α-TCDD complexes estimated by the molecular mechanics/Poisson-Boltzmann surface area(MM/PBSA) method are from -85.1 kJ/mol to-114.3 kJ/mol for maize and are from-96.1 kJ/mol to-118.2 kJ/mol for human,which are comparable to those estimated for the known inhibitor and also ATP with CK2α.The energetic analysis also reveals that the van der Waals interaction is the dominant contribution to the binding free energy.These results are also useful for designing new drugs for a target of overexpressing CK2 in cancers.

  13. miR-502 inhibits cell proliferation and tumor growth in hepatocellular carcinoma through suppressing phosphoinositide 3-kinase catalytic subunit gamma

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Suling, E-mail: suling_chen86@163.com [Department of Infectious Disease, Heping Hospital Attached to Changzhi Medical College, Changzhi 046000 (China); Li, Fang; Chai, Haiyun; Tao, Xin [Department of Infectious Disease, Heping Hospital Attached to Changzhi Medical College, Changzhi 046000 (China); Wang, Haili [Department of Hematology, Heping Hospital Attached to Changzhi Medical College, Changzhi 046000 (China); Ji, Aifang [Central Laboratory, Heping Hospital Attached to Changzhi Medical College, Changzhi 046000 (China)

    2015-08-21

    MicroRNAs (miRNAs) play a key role in carcinogenesis and tumor progression in hepatocellular carcinoma (HCC). In the present study, we demonstrated that miR-502 significantly inhibits HCC cell proliferation in vitro and tumor growth in vivo. G1/S cell cycle arrest and apoptosis of HCC cells were induced by miR-502. Phosphoinositide 3-kinase catalytic subunit gamma (PIK3CG) was identified as a direct downstream target of miR-502 in HCC cells. Notably, overexpression of PIK3CG reversed the inhibitory effects of miR-502 in HCC cells. Our findings suggest that miR-502 functions as a tumor suppressor in HCC via inhibition of PI3KCG, supporting its utility as a promising therapeutic gene target for this tumor type. - Highlights: • miR-502 suppresses HCC cell proliferation in vitro and tumorigenicity in vivo. • miR-502 regulates cell cycle and apoptosis in HCC cells. • PIK3CG is a direct target of miR-502. • miR-502 and PIK3CG expression patterns are inversely correlated in HCC tissues.

  14. The differentiation status of primary gonadal germ cell tumors correlates inversely with telomerase activity and the expression level of the gene encoding the catalytic subunit of telomerase

    International Nuclear Information System (INIS)

    The activity of the ribonucleoprotein enzyme telomerase is detectable in germ, stem and tumor cells. One major component of telomerase is human telomerase reverse transcriptase (hTERT), which encodes the catalytic subunit of telomerase. Here we investigate the correlation of telomerase activity and hTERT gene expression and the differentiation status of primary testicular germ cell tumors (TGCT). Telomerase activity (TA) was detected by a quantitative telomerase PCR ELISA, and hTERT mRNA expression was quantified by online RT-PCR in 42 primary testicular germ cell tumors. The control group consisted of benign testicular biopsies from infertile patients. High levels of telomerase activity and hTERT expression were detected in all examined undifferentiated TGCTs and in the benign testicular tissue specimens with germ cell content. In contrast, differentiated teratomas and testicular control tissue without germ cells (Sertoli-cell-only syndrome) showed no telomerase activity and only minimal hTERT expression. These findings demonstrate an inverse relationship between the level of telomerase activity and hTERT mRNA expression and the differentiation state of germ cell tumors. Quantification of telomerase activity and hTERT mRNA expression enables a new molecular-diagnostic subclassification of germ cell tumors that describes their proliferation potential and differentiation status

  15. Detection of „Hotspot Mutations in Catalytic Subunit of Phosphatidylinositol 3-Kinase (Pik3ca by Allele-Specific Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    A. Mendelova

    2014-09-01

    Full Text Available The phosphatidylinositol 3-kinases (PI3Ks are a family of proteins involved in the regulation of cell survival, growth, metabolism, and glucose homeostasis. Increased PI3K activity is associated with many cancers. PIK3CA gene (encoding p110 , the catalytic subunit of PI3K is commonly mutated in breast cancer. In our study we focused on the detection of “hotspot” mutations in exons 9 and 20 of the PIK3CA gene in paraffin-embedded tissue of patients with breast cancer. We optimized conditions of allele specific polymerase chain reaction (PCR and we used direct sequencing to verify our results. Overall, three “hotspot” mutations in PIK3CA gene in paraffin-embadded tissue from breast cancer were detected by allele-specific PCR. All results were verified by direct sequencing of PCR products and we observed 100% agreement between those two methods. We confirmed that allele-specific PCR assay is low cost method usefull for accurate detection of PIK3CA mutations.

  16. Healthcare under the Panchayati Raj Institutions (PRIs) in a decentralised health system.

    Science.gov (United States)

    Kumar, Virendra; Jayanta Mishra, Anindya

    2016-05-01

    Purpose This paper aims to explore the challenges and benefits arising from the involvement of Panchayati Raj Institutions (PRIs) in the provisioning of primary healthcare in a decentralised health system of India. Design/methodology/approach A qualitative study design was used in this study. Data were collected through semi-structured interviews from 89 respondents selected from nine primary health centres across the district. A thematic analytical framework approach was used to analyse the data. Findings The research results indicate that there are several challenges resulting from PRIs involvement, including prioritisation of service providers and users, coercive unethical work and lack of communication. However, there are some benefits associated with the involvement of the PRIs in service provisioning, including improved availability and regularity of healthcare providers at the health centres. Research limitations/implications The implications of the findings suggest that the PRIs play an important role in healthcare provisioning; however, their involvement is ineffective due to their partial capabilities and approach, which creates a non-conducive environment. Practical implications Health issues are among the most important human concerns, and recognising and addressing the grassroot challenges help to locate, and overcome the challenges that hinder the smooth healthcare provisioning process. Originality/value National Rural Health Mission has recognised the PRIs as a platform to promote decentralised health planning and for achieving its goals in India. The PRIs are significantly involved in planning, monitoring and provisioning of primary healthcare services at grassroot level. This paper addresses the challenges and benefits that emerged due to their involvement. PMID:27198704

  17. Polo-like kinase 1 (PLK1) and protein phosphatase 6 (PP6) regulate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation in mitosis.

    Science.gov (United States)

    Douglas, Pauline; Ye, Ruiqiong; Trinkle-Mulcahy, Laura; Neal, Jessica A; De Wever, Veerle; Morrice, Nick A; Meek, Katheryn; Lees-Miller, Susan P

    2014-01-01

    The protein kinase activity of the DNA-PKcs (DNA-dependent protein kinase catalytic subunit) and its autophosphorylation are critical for DBS (DNA double-strand break) repair via NHEJ (non-homologous end-joining). Recent studies have shown that depletion or inactivation of DNA-PKcs kinase activity also results in mitotic defects. DNA-PKcs is autophosphorylated on Ser2056, Thr2647 and Thr2609 in mitosis and phosphorylated DNA-PKcs localize to centrosomes, mitotic spindles and the midbody. DNA-PKcs also interacts with PP6 (protein phosphatase 6), and PP6 has been shown to dephosphorylate Aurora A kinase in mitosis. Here we report that DNA-PKcs is phosphorylated on Ser3205 and Thr3950 in mitosis. Phosphorylation of Thr3950 is DNA-PK-dependent, whereas phosphorylation of Ser3205 requires PLK1 (polo-like kinase 1). Moreover, PLK1 phosphorylates DNA-PKcs on Ser3205 in vitro and interacts with DNA-PKcs in mitosis. In addition, PP6 dephosphorylates DNA-PKcs at Ser3205 in mitosis and after IR (ionizing radiation). DNA-PKcs also phosphorylates Chk2 on Thr68 in mitosis and both phosphorylation of Chk2 and autophosphorylation of DNA-PKcs in mitosis occur in the apparent absence of Ku and DNA damage. Our findings provide mechanistic insight into the roles of DNA-PKcs and PP6 in mitosis and suggest that DNA-PKcs' role in mitosis may be mechanistically distinct from its well-established role in NHEJ.

  18. O-GlcNAcylation of protein kinase A catalytic subunits enhances its activity: a mechanism linked to learning and memory deficits in Alzheimer's disease.

    Science.gov (United States)

    Xie, Shutao; Jin, Nana; Gu, Jianlan; Shi, Jianhua; Sun, Jianming; Chu, Dandan; Zhang, Liang; Dai, Chun-Ling; Gu, Jin-Hua; Gong, Cheng-Xin; Iqbal, Khalid; Liu, Fei

    2016-06-01

    Alzheimer's disease (AD) is characterized clinically by memory loss and cognitive decline. Protein kinase A (PKA)-CREB signaling plays a critical role in learning and memory. It is known that glucose uptake and O-GlcNAcylation are reduced in AD brain. In this study, we found that PKA catalytic subunits (PKAcs) were posttranslationally modified by O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation regulated the subcellular location of PKAcα and PKAcβ and enhanced their kinase activity. Upregulation of O-GlcNAcylation in metabolically active rat brain slices by O-(2-acetamido-2-deoxy-d-glucopyranosylidenamino) N-phenylcarbamate (PUGNAc), an inhibitor of N-acetylglucosaminidase, increased the phosphorylation of tau at the PKA site, Ser214, but not at the non-PKA site, Thr205. In contrast, in rat and mouse brains, downregulation of O-GlcNAcylation caused decreases in the phosphorylation of CREB at Ser133 and of tau at Ser214, but not at Thr205. Reduction in O-GlcNAcylation through intracerebroventricular injection of 6-diazo-5-oxo-l-norleucine (DON), the inhibitor of glutamine fructose-6-phosphate amidotransferase, suppressed PKA-CREB signaling and impaired learning and memory in mice. These results indicate that in addition to cAMP and phosphorylation, O-GlcNAcylation is a novel mechanism that regulates PKA-CREB signaling. Downregulation of O-GlcNAcylation suppresses PKA-CREB signaling and consequently causes learning and memory deficits in AD. PMID:26840030

  19. Phosphatidyl-inositol-3-kinase alpha catalytic subunit mutation and response to neoadjuvant endocrine therapy for estrogen receptor positive breast cancer

    Science.gov (United States)

    Ellis, Matthew J; Lin, Li; Crowder, Robert; Tao, Yu; Hoog, Jeremy; Snider, Jacqueline; Davies, Sherri; DeSchryver, Katherine; Evans, Dean B; Steinseifer, Jutta; Bandaru, Raj; Liu, WeiHua; Gardner, Humphrey; Semiglazov, Vladimir; Watson, Mark; Hunt, Kelly; Olson, John; Baselga, José

    2010-01-01

    Background Mutations in the alpha catalytic subunit of phosphoinositol-3-kinase (PIK3CA) occur in ~30% of ER positive breast cancers. We therefore sought to determine the impact of PIK3CA mutation on response to neoadjuvant endocrine therapy. Methods Exon 9 (helical domain - HD) and Exon 20 (kinase domain- KD) mutations in PIK3CA were determined samples from four neoadjuvant endocrine therapy trials. Interactions with clinical, pathological and biomarker response parameters were examined. Results A weak negative interaction between PIK3CA mutation status and clinical response to neoadjuvant endocrine treatment was detected (N=235 P=<0.05), but not with treatment-induced changes in Ki67-based proliferation index (N=418). Despite these findings, PIK3CA KD mutation was a favorable prognostic factor for relapse-free survival (RFS log rank P=0.02) in the P024 trial (N=153). The favorable prognostic effect was maintained in a multivariable analysis (N=125) that included the preoperative prognostic index (PEPI), an approach to predicting RFS based on post neoadjuvant endocrine therapy pathological stage, ER and Ki67 levels (HR for no PIK3CA KD mutation, 14, CI 1.9–105 P=0.01). Conclusion PIK3CA mutation status did not strongly interact with neoadjuvant endocrine therapy responsiveness in estrogen receptor positive breast cancer. Nonetheless, as with other recent studies, a favorable interaction between PIK3CA kinase domain mutation and prognosis was detected. The mechanism for the favorable prognostic impact of PIK3CA mutation status therefore remains unexplained. PMID:19844788

  20. Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

    Energy Technology Data Exchange (ETDEWEB)

    Boylan, Joan M. [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Salomon, Arthur R. [Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States); Department of Chemistry, Brown University, Providence, RI (United States); Tantravahi, Umadevi [Division of Genetics, Department of Pathology, Brown University and Women and Infants Hospital, Providence, RI (United States); Gruppuso, Philip A., E-mail: philip_gruppuso@brown.edu [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States)

    2015-07-15

    Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders. - Highlights: • Lentiviral-transduced shRNA was used to generate a stable knockdown of PP6 in HepG2 cells. • Cells adapted to reduced PP6; cell proliferation was unaffected, and cell survival was normal. • However, PP6 knockdown was associated with a transition to a tetraploid state. • Genomic profiling showed downregulated anti-inflammatory signaling and DNA replication. • Phosphoproteomic profiling showed changes in proteins associated with DNA replication and repair.

  1. Viviane Alary, Nelly Chabrol-Gagne (dir., L’album. Le parti pris des images

    Directory of Open Access Journals (Sweden)

    Clémentine Beauvais

    2012-11-01

    Full Text Available « La rencontre coruscante de l’image et du texte baptisée iconotexte », comme l’exprime élégamment Laurence Olivier-Messonnier (p. 55, constitue l’objet d’étude de cet ouvrage universitaire touffu et, malgré la diversité historique, géographique et méthodologique de ses chapitres, idéologiquement harmonieux. S’il y a un parti pris dans ce Parti pris des images, c’est, comme la poésie de Ponge à laquelle il fait délicatement allusion, la conviction qu’il existe, au-delà de la séduisante imméd...

  2. Green fluorescent protein fused to subunitγ of the F1F0ATP synthase central rotor as a tool to probe the structure of the F1 catalytic sector

    International Nuclear Information System (INIS)

    High-resolution X-ray crystal structures are available for the F1 catalytic sector of ATP synthase. However, the structure at the very top of F1, surrounding a 'dimple' is poorly resolved. This may reflect that this region of the complex undergoes important conformational changes during catalysis. Recently, a cap structure covering the dimple, but not resolved in X-ray crystal structures, has been visualised in electron micrographs of the complex. Conservation of structure between mitochondrial complexes would suggest such a feature would be maintained in yeast (Saccharomyces cerevisiae). Our approach to investigating the nature of the 'cap' is based on the use of GFP fusion proteins. Specifically we have determined whether yeast subunit γ linked at its C-terminus to GFP, and which would be expected to protrude through the 'dimple' space, is functional. Subunit γ tethered to the N-terminus of YEGFP3 via a 27 or a 4 amino acid polypeptide was expressed in yeast cells lacking endogenous subunit γ. Cells expressing either of these fusion proteins contained functional ATP synthase complexes, as demonstrated by the ability of these cells to utilise the respiratory substrate ethanol for growth. Analysis of mitochondrial lysates on native gels (and subsequent western blotting) indicated that the ATP synthase complexes were correctly assembled and fluorescent, containing γ-GFP fusion protein. Collectively, these results indicate that in vivo ATP synthase complexes are able to assemble and function with a C-terminal tagged version of subunit γ. Computer modelling suggests that the C-terminal GFP moiety containing the γ-27-GFP fusion protein is expected to extend well beyond the proposed position of the cap structure. In the case of the γ-4-GFP fusion protein the GFP moiety is expected to extend only some short distance above the top of F1. In both cases subunit γ must at all times during the catalytic cycle protrude through the 'dimple' space into the mitochondrial

  3. High glucose exposure promotes activation of protein phosphatase 2A in rodent islets and INS-1 832/13 β-cells by increasing the posttranslational carboxylmethylation of its catalytic subunit.

    Science.gov (United States)

    Arora, Daleep K; Machhadieh, Baker; Matti, Andrea; Wadzinski, Brian E; Ramanadham, Sasanka; Kowluru, Anjaneyulu

    2014-02-01

    Existing evidence implicates regulatory roles for protein phosphatase 2A (PP2A) in a variety of cellular functions, including cytoskeletal remodeling, hormone secretion, and apoptosis. We report here activation of PP2A in normal rat islets and insulin-secreting INS-1 832/13 cells under the duress of hyperglycemic (HG) conditions. Small interfering RNA-mediated knockdown of the catalytic subunit of PP2A (PP2Ac) markedly attenuated glucose-induced activation of PP2A. HG, but not nonmetabolizable 3-O-methyl glucose or mannitol (osmotic control), significantly stimulated the methylation of PP2Ac at its C-terminal Leu-309, suggesting a novel role for this posttranslational modification in glucose-induced activation of PP2A. Moreover, knockdown of the cytosolic leucine carboxymethyl transferase 1 (LCMT1), which carboxymethylates PP2Ac, significantly attenuated PP2A activation under HG conditions. In addition, HG conditions, but not 3-O-methyl glucose or mannitol, markedly increased the expression of LCMT1. Furthermore, HG conditions significantly increased the expression of B55α, a regulatory subunit of PP2A, which has been implicated in islet dysfunction under conditions of oxidative stress and diabetes. Thapsigargin, a known inducer of endoplasmic reticulum stress, failed to exert any discernible effects on the carboxymethylation of PP2Ac, expression of LCMT1 and B55α, or PP2A activity, suggesting no clear role for endoplasmic reticulum stress in HG-induced activation of PP2A. Based on these findings, we conclude that exposure of the islet β-cell to HG leads to accelerated PP2A signaling pathway, leading to loss in glucose-induced insulin secretion. PMID:24265448

  4. Criminologia e Prisão: caminhos e desafios da pesquisa empírica no campo prisional

    Directory of Open Access Journals (Sweden)

    Ana Gabriela Mendes Braga

    2014-01-01

    Full Text Available O presente artigo é um dos frutos da pesquisa de doutoramento “Reintegração social: discursos e práticas na prisão ‒ um estudo comparado”, na qual foram analisados alguns projetos desenvolvidos por entidades da sociedade civil em estabelecimentos prisionais de São Paulo e da Catalunha (Espanha. Para tanto, utilizou-se metodologia qualitativa de pesquisa, com o emprego de três métodos: entrevistas semidirigidas com os envolvidos direta e indiretamente com os projetos (voluntários, presos, diretores de entidades, funcionários da prisão; pesquisa documental (projetos, memoriais, manuais; e, relatos etnográficos produzidos a partir da observação in loco do trabalho desenvolvido pelas entidades selecionadas nos estabelecimentos prisionais. Neste paper, ganha destaque a questão do método em criminologia e as reflexões acerca da pesquisa empírica na prisão. Em uma pesquisa situada em um espaço tão hermético como a prisão, explicitar os caminhos de inserção do campo é um exercício que desvela os mecanismos de poder em funcionamento, e acaba por levar o pesquisador de volta ao objeto da própria tese. Afinal, muitos dos empecilhos e barreiras criadas para a entrada do pesquisador na prisão são os mesmos com que se deparam as entidades e pessoas da sociedade civil. Esse artigo é uma reflexão acerca dos caminhos e dos desafios vivenciados por aqueles que adentram o espaço prisional enfrentando o isolamento impostos por seus muros.

  5. Interaction of factor XIII subunits.

    Science.gov (United States)

    Katona, Eva; Pénzes, Krisztina; Csapó, Andrea; Fazakas, Ferenc; Udvardy, Miklós L; Bagoly, Zsuzsa; Orosz, Zsuzsanna Z; Muszbek, László

    2014-03-13

    Coagulation factor XIII (FXIII) is a heterotetramer consisting of 2 catalytic A subunits (FXIII-A2) and 2 protective/inhibitory B subunits (FXIII-B2). FXIII-B, a mosaic protein consisting of 10 sushi domains, significantly prolongs the lifespan of catalytic subunits in the circulation and prevents their slow progressive activation in plasmatic conditions. In this study, the biochemistry of the interaction between the 2 FXIII subunits was investigated. Using a surface plasmon resonance technique and an enzyme-linked immunosorbent assay-type binding assay, the equilibrium dissociation constant (Kd) for the interaction was established in the range of 10(-10) M. Based on the measured Kd, it was calculated that in plasma approximately 1% of FXIII-A2 should be in free form. This value was confirmed experimentally by measuring FXIII-A2 in plasma samples immunodepleted of FXIII-A2B2. Free plasma FXIII-A2 is functionally active, and when activated by thrombin and Ca(2+), it can cross-link fibrin. In cerebrospinal fluid and tears with much lower FXIII subunit concentrations, >80% of FXIII-A2 existed in free form. A monoclonal anti-FXIII-B antibody that prevented the interaction between the 2 subunits reacted with the recombinant combined first and second sushi domains of FXIII-B, and its epitope was localized to the peptide spanning positions 96 to 103 in the second sushi domain. PMID:24408323

  6. Silencing expression of the catalytic subunit of DNA-dependent protein kinase by small interfering RNA sensitizes human cells for radiation-induced chromosome damage, cell killing, and mutation

    Science.gov (United States)

    Peng, Yuanlin; Zhang, Qinming; Nagasawa, Hatsumi; Okayasu, Ryuichi; Liber, Howard L.; Bedford, Joel S.

    2002-01-01

    Targeted gene silencing in mammalian cells by RNA interference (RNAi) using small interfering RNAs (siRNAs) was recently described by Elbashir et al. (S. M. Elbashir et al., Nature (Lond.), 411: 494-498, 2001). We have used this methodology in several human cell strains to reduce expression of the Prkdc (DNA-PKcs) gene coding for the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs) that is involved in the nonhomologous end joining of DNA double-strand breaks. We have also demonstrated a radiosensitization for several phenotypic endpoints of radiation damage. In low-passage normal human fibroblasts, siRNA knock-down of DNA-PKcs resulted in a reduced capacity for restitution of radiation-induced interphase chromosome breaks as measured by premature chromosome condensation, an increased yield of acentric chromosome fragments at the first postirradiation mitosis, and an increased radiosensitivity for cell killing. For three strains of related human lymphoblasts, DNA-PKcs-targeted siRNA transfection resulted in little or no increase in radiosensitivity with respect to cell killing, a 1.5-fold decrease in induced mutant yield in TK6- and p53-null NH32 cells, but about a 2-fold increase in induced mutant yield in p53-mutant WTK1 cells at both the hypoxanthine quanine phosphoribosyl transferase (hprt) and the thymidine kinase loci.

  7. A Novel Interaction of the Catalytic Subunit of Protein Phosphatase 2A with the Adaptor Protein CIN85 Suppresses Phosphatase Activity and Facilitates Platelet Outside-in αIIbβ3 Integrin Signaling.

    Science.gov (United States)

    Khatlani, Tanvir; Pradhan, Subhashree; Da, Qi; Shaw, Tanner; Buchman, Vladimir L; Cruz, Miguel A; Vijayan, K Vinod

    2016-08-12

    The transduction of signals generated by protein kinases and phosphatases are critical for the ability of integrin αIIbβ3 to support stable platelet adhesion and thrombus formation. Unlike kinases, it remains unclear how serine/threonine phosphatases engage the signaling networks that are initiated following integrin ligation. Because protein-protein interactions form the backbone of signal transduction, we searched for proteins that interact with the catalytic subunit of protein phosphatase 2A (PP2Ac). In a yeast two-hybrid study, we identified a novel interaction between PP2Ac and an adaptor protein CIN85 (Cbl-interacting protein of 85 kDa). Truncation and alanine mutagenesis studies revealed that PP2Ac binds to the P3 block ((396)PAIPPKKPRP(405)) of the proline-rich region in CIN85. The interaction of purified PP2Ac with CIN85 suppressed phosphatase activity. Human embryonal kidney 293 αIIbβ3 cells overexpressing a CIN85 P3 mutant, which cannot support PP2Ac binding, displayed decreased adhesion to immobilized fibrinogen. Platelets contain the ∼85 kDa CIN85 protein along with the PP2Ac-CIN85 complex. A myristylated cell-permeable peptide derived from residues 395-407 of CIN85 protein (P3 peptide) disrupted the platelet PP2Ac-CIN85 complex and decreased αIIbβ3 signaling dependent functions such as platelet spreading on fibrinogen and thrombin-mediated fibrin clot retraction. In a phospho-profiling study P3 peptide treated platelets also displayed decreased phosphorylation of several signaling proteins including Src and GSK3β. Taken together, these data support a role for the novel PP2Ac-CIN85 complex in supporting integrin-dependent platelet function by dampening the phosphatase activity. PMID:27334924

  8. Cystatins as calpain inhibitors: engineered chicken cystatin- and stefin B-kininogen domain 2 hybrids support a cystatin-like mode of interaction with the catalytic subunit of mu-calpain.

    Science.gov (United States)

    Díaz, B G; Gross, S; Assfalg-Machleidt, I; Pfeiler, D; Gollmitzer, N; Gabrijelcic-Geiger, D; Stubbs, M T; Fritz, H; Auerswald, E A; Machleidt, W

    2001-01-01

    Within the cystatin superfamily, only kininogen domain 2 (KD2) is able to inhibit mu- and m-calpain. In an attempt to elucidate the structural requirements of cystatins for calpain inhibition, we constructed recombinant hybrids of human stefin B (an intracellular family 1 cystatin) with KD2 and deltaL110 deletion mutants of chicken cystatin-KD2 hybrids. Substitution of the N-terminal contact region of stefin B by the corresponding KD2 sequence resulted in a calpain inhibitor of Ki = 188 nM. Deletion of L110, which forms a beta-bulge in family 1 and 2 cystatins but is lacking in KD2, improved inhibition of mu-calpain 4- to 8-fold. All engineered cystatins were temporary inhibitors of calpain due to slow substrate-like cleavage of a single peptide bond corresponding to Gly9-Ala10 in chicken cystatin. Biomolecular interaction analysis revealed that, unlike calpastatin, the cystatin-type inhibitors do not bind to the calmodulin-like domain of the small subunit of calpain, and their interaction with the mu-calpain heterodimer is completely prevented by a synthetic peptide comprising subdomain B of calpastatin domain 1. Based on these results we propose that (i) cystatin-type calpain inhibitors interact with the active site of the catalytic domain of calpain in a similar cystatin-like mode as with papain and (ii) the potential for calpain inhibition is due to specific subsites within the papain-binding regions of the general cystatin fold.

  9. Reconnaissance et gouvernement des salariés. Au-delà du mépris

    OpenAIRE

    Heller, Thomas

    2012-01-01

    La notion de pathologie sociale de la communication sera appréhendée en relation avec le concept de reconnaissance, développé par le philosophe et sociologue Axel Honneth, et ici rapporté à la communication au sein des organisations. Mais au-delà du rapport entre communication et mépris par lequel se manifeste le pathologique, c’est dans son aspect problématique, dans l’indécidabilité de la valeur éthique de la reconnaissance, que ce rapport est interrogé. Il s’agit moins de mettre au jour le...

  10. Telomerase Holoenzyme Proteins and Processivity Subunit in Tetrahymena thermophila

    OpenAIRE

    Min, Bosun

    2009-01-01

    Telomeres are specialized protein-DNA structures that protect the ends of linear chromosomes, and they are maintained by the telomerase ribonucleoprotein (RNP) enzyme complex. Recombinant telomerase RNP with catalytic activity contains, at a minimum, the catalytic reverse transcriptase subunit (TERT) and the telomerase RNA (TER). However, endogenous telomerase is a much larger holoenzyme complex, with telomerase-associated subunits that contribute to RNP assembly and regulation. Telomerase-as...

  11. Subunit interactions change the heme active-site geometry in p-cresol methylhydroxylase.

    OpenAIRE

    McLendon, G L; Bagby, S; Charman, J A; Driscoll, P. C.; McIntire, W S; Mathews, F. S.; Hill, H A

    1991-01-01

    The enzyme p-cresol methylhydroxylase [4-cresol: (acceptor) oxidoreductase (methyl-hydroxylating), EC 1.17.99.1] contains two subunits: a cytochrome c (electron transfer) subunit (cytochrome cpc) and a flavin (catalytic) subunit. When these subunits are separated by isoelectric focusing, a stable cytochrome subunit is obtained. Significant differences are observed between the one-dimensional NMR spectra of oxidized cytochrome cpc and of oxidized p-cresol methylhydroxylase. Analysis of the two...

  12. A revised model for AMP-activated protein kinase structure: The alpha-subunit binds to both the beta- and gamma-subunits although there is no direct binding between the beta- and gamma-subunits.

    Science.gov (United States)

    Wong, Kelly A; Lodish, Harvey F

    2006-11-24

    The 5'-AMP-activated protein kinase (AMPK) is a master sensor for cellular metabolic energy state. It is activated by a high AMP/ATP ratio and leads to metabolic changes that conserve energy and utilize alternative cellular fuel sources. The kinase is composed of a heterotrimeric protein complex containing a catalytic alpha-subunit, an AMP-binding gamma-subunit, and a scaffolding beta-subunit thought to bind directly both the alpha- and gamma-subunits. Here, we use coimmunoprecipitation of proteins in transiently transfected cells to show that the alpha2-subunit binds directly not only to the beta-subunit, confirming previous work, but also to the gamma1-subunit. Deletion analysis of the alpha2-subunit reveals that the C-terminal 386-552 residues are sufficient to bind to the beta-subunit. The gamma1-subunit binds directly to the alpha2-subunit at two interaction sites, one within the catalytic domain consisting of alpha2 amino acids 1-312 and a second within residues 386-552. Binding of the alpha2 and the gamma1-subunits was not affected by 400 mum AMP or ATP. Furthermore, we show that the beta-subunit C terminus is essential for binding to the alpha2-subunit but, in contrast to previous work, the beta-subunit does not bind directly to the gamma1-subunit. Taken together, this study presents a new model for AMPK heterotrimer structure where through its C terminus the beta-subunit binds to the alpha-subunit that, in turn, binds to the gamma-subunit. There is no direct interaction between the beta- and gamma-subunits.

  13. Role of the beta subunit of casein kinase-2 on the stability and specificity of the recombinant reconstituted holoenzyme

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Marin, O;

    1992-01-01

    Recombinant human alpha subunit from casein kinase-2 (CK-2) was subjected, either alone or in combination with recombinant human beta subunit, to high temperature, tryptic digestion and urea treatment. In all three cases, it was shown that the presence of the beta subunit could drastically reduce...... alpha subunit. Therefore, a dual function for the beta subunit is proposed which confers both specificity and stability to the catalytic alpha subunit within the CK-2 holoenzyme complex. The peptide DLEPDEELEDNPNQSDL, reproducing the highly acidic amino acid 55-71 segment of the human beta subunit......, counteracts the stimulatory effect of the beta subunit on the alpha subunit activity and partially substitutes the beta subunit in conferring thermal stability to the alpha subunit. No such effect is induced by the peptide MSSSEEVSW, reproducing the N-terminal segment of the beta subunit including...

  14. DMU-forskere får EU's miljøpris for at bekæmpe græshopper

    DEFF Research Database (Denmark)

    Voigt, Steen

    2008-01-01

    Et forskerhold bestående af Jørgen Aagaard Axelsen, Jesper Bak, Peter Borgen Sørensen og Idrissa Maiga (i Niger) fra Danmarks Miljøundersøgelser (DMU) ved Aarhus Universitet er blandt årets danske modtagere af EU's miljøpris. Prisen, som Ingeniørforeningen i Danmark på vegne af EU står for overræ...

  15. The education inside prison: hesitations, limits and possibilities A educação na prisão: hesitações, limites e possibilidades

    Directory of Open Access Journals (Sweden)

    Mariângela Graciano

    2008-12-01

    Full Text Available This article aims to analyze the school education offer inside the prison system of São Paulo, based on the thoughts proposed by Foucault (1986 about prison, its aims and functioning mechanisms. What would be the possible place for education inside e prison? These are some questions that surround this debate and draw the central boards of a history which can be qualifi ed, at least, as hesitating, about prison education. In order to found this debate, we discuss the prison education as part of the Education of Young and Adults, its relation to the Human Rights, is legal and administrational outlines and, specifically, the case of school education inside de Women’s Prison of the Capital. Keywords: Education. Prisons. Human rights. Este artigo busca analisar a oferta da educação escolar no sistema prisional de São Paulo com base nas reflexões propostas por Foucault (1988 acerca da prisão, seus objetivos e mecanismos de funcionamento Qual seria o lugar possível da educação em uma prisão? Estas são algumas interrogações que permeiam este debate e traçam os contornos centrais de uma história que pode ser qualificada, no mínimo, como “hesitante”, em torno da educação prisional. Para fundamentar este debate discute-se a educação prisional como uma modalidade da Educação de Jovens e Adultos, sua relação com os Direitos Humanos, seus contornos legais e administrativos e, especificamente, o caso da educação escolar na Penitenciária Feminina da Capital. Palavras-chave: Educação. Prisões. Direitos humanos.

  16. Factores de risco associados à ideação suicida durante a prisão preventiva : estudo exploratório

    OpenAIRE

    Moreira, Nuno Alexandre Costa

    2009-01-01

    Dissertação de mestrado em Psicologia (área de conhecimento em Psicologia da Justiça) As taxas de comportamentos suicidários nas prisões portuguesas são extraordinariamente elevadas comparativamente às observadas entre a população geral, não se conhecendo estudos empíricos que se tenham debruçado sobre os factores de risco associados a este fenómeno. O presente estudo tenta colmatar essa lacuna, abrindo caminho a futuras investigações sobre comportamentos suicidários em meio prisional. ...

  17. Protein Kinase A Subunit Balance Regulates Lipid Metabolism in Caenorhabditis elegans and Mammalian Adipocytes.

    Science.gov (United States)

    Lee, Jung Hyun; Han, Ji Seul; Kong, Jinuk; Ji, Yul; Lv, Xuchao; Lee, Junho; Li, Peng; Kim, Jae Bum

    2016-09-23

    Protein kinase A (PKA) is a cyclic AMP (cAMP)-dependent protein kinase composed of catalytic and regulatory subunits and involved in various physiological phenomena, including lipid metabolism. Here we demonstrated that the stoichiometric balance between catalytic and regulatory subunits is crucial for maintaining basal PKA activity and lipid homeostasis. To uncover the potential roles of each PKA subunit, Caenorhabditis elegans was used to investigate the effects of PKA subunit deficiency. In worms, suppression of PKA via RNAi resulted in severe phenotypes, including shortened life span, decreased egg laying, reduced locomotion, and altered lipid distribution. Similarly, in mammalian adipocytes, suppression of PKA regulatory subunits RIα and RIIβ via siRNAs potently stimulated PKA activity, leading to potentiated lipolysis without increasing cAMP levels. Nevertheless, insulin exerted anti-lipolytic effects and restored lipid droplet integrity by antagonizing PKA action. Together, these data implicate the importance of subunit stoichiometry as another regulatory mechanism of PKA activity and lipid metabolism.

  18. Specific Inhibition of Herpes Simplex Virus DNA Polymerase by Helical Peptides Corresponding to the Subunit Interface

    Science.gov (United States)

    Digard, Paul; Williams, Kevin P.; Hensley, Preston; Brooks, Ian S.; Dahl, Charles E.; Coen, Donald M.

    1995-02-01

    The herpes simplex virus DNA polymerase consists of two subunits-a catalytic subunit and an accessory subunit, UL42, that increases processivity. Mutations affecting the extreme C terminus of the catalytic subunit specifically disrupt subunit interactions and ablate virus replication, suggesting that new antiviral drugs could be rationally designed to interfere with polymerase heterodimerization. To aid design, we performed circular dichroism (CD) spectroscopy and analytical ultracentrifugation studies, which revealed that a 36-residue peptide corresponding to the C terminus of the catalytic subunit folds into a monomeric structure with partial α-helical character. CD studies of shorter peptides were consistent with a model where two separate regions of α-helix interact to form a hairpin-like structure. The 36-residue peptide and a shorter peptide corresponding to the C-terminal 18 residues blocked UL42-dependent long-chain DNA synthesis at concentrations that had no effect on synthesis by the catalytic subunit alone or by calf thymus DNA polymerase δ and its processivity factor. These peptides, therefore, represent a class of specific inhibitors of herpes simplex virus DNA polymerase that act by blocking accessory-subunit-dependent synthesis. These peptides or their structures may form the basis for the synthesis of clinically effective drugs.

  19. Structure of protein kinase CK2: dimerization of the human beta-subunit

    DEFF Research Database (Denmark)

    Boldyreff, B; Mietens, U; Issinger, O G

    1996-01-01

    Protein kinase CK2 has been shown to be elevated in all so far investigated solid tumors and its catalytic subunit has been shown to serve as an oncogene product. CK2 is a heterotetrameric serine-threonine kinase composed of two catalytic (alpha and/or alpha') and two regulatory beta...

  20. De la négociation à l’imposition : le risque d’un retour en arrière, d’un retour au mépris

    OpenAIRE

    Gagnon, Mathieu

    2013-01-01

    L’évolution des relations entre autochtones et allochtones depuis les années 1970 fait croire à plusieurs que ces relations ne peuvent aller qu’en s’améliorant. Néanmoins, l’État canadien ne s’est toujours pas sorti de la relation coloniale vis-à-vis des Premières Nations, relation qui impliqua historiquement de nombreuses manifestations de mépris à leur endroit, mépris qui fut souvent invisible aux yeux de ceux qui le portaient et se croyaient bien intentionnés. Dans une analyse fonctionnell...

  1. Interaction between CK2α and CK2β, the subunits of protein kinase CK2: thermodynamic contributions of key residues on the CK2α surface

    DEFF Research Database (Denmark)

    Raaf, Jennifer; Bischoff, Nils; Klopffleisch, Karsten;

    2011-01-01

    The protein Ser/Thr kinase CK2 (former name: casein kinase II) exists predominantly as a heterotetrameric holoenzyme composed of two catalytic subunits (CK2α) bound to a dimer of noncatalytic subunits (CK2β). We undertook a study to further understand how these subunits interact to form the tetra...

  2. Transcriptional regulators of Na, K-ATPase subunits

    Directory of Open Access Journals (Sweden)

    Zhiqin eLi

    2015-10-01

    Full Text Available The Na,K-ATPase classically serves as an ion pump creating an electrochemical gradient across the plasma membrane that is essential for transepithelial transport, nutrient uptake and membrane potential. In addition, Na,K-ATPase also functions as a receptor, a signal transducer and a cell adhesion molecule. With such diverse roles, it is understandable that the Na,K-ATPase subunits, the catalytic alpha-subunit, the beta-subunit and the FXYD proteins, are controlled extensively during development and to accommodate physiological needs. The spatial and temporal expression of Na,K-ATPase is partially regulated at the transcriptional level. Numerous transcription factors, hormones, growth factors, lipids and extracellular stimuli modulate the transcription of the Na,K-ATPase subunits. Moreover, epigenetic mechanisms also contribute to the regulation of Na,K-ATPase expression. With the ever growing knowledge about diseases associated with the malfunction of Na,K-ATPase, this review aims at summarizing the best-characterized transcription regulators that modulate Na,K-ATPase subunit levels. As abnormal expression of Na,K-ATPase subunits have been observed in many carcinoma, we will also discuss transcription factors that are associated with epithelial-to-mesenchymal transition, a crucial step in the progression of many tumors to malignant disease.

  3. Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A

    OpenAIRE

    Janssens Veerle; Goris Jozef; Louis Justin V; Zwaenepoel Karen

    2008-01-01

    Abstract Background Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specifici...

  4. Cloning and Sequence Analysis of Lateolabrax japonicus Glucose-6-phosphatase Catalytic Subunit (G6PC) cDNA and Its 5'-flanking Region%鲈鱼6-磷酸葡萄糖酶催化亚基(G6PC)cDNA和5’侧翼序列的克隆及分析

    Institute of Scientific and Technical Information of China (English)

    钱云霞; 郑伟贤; 宋娟娟

    2011-01-01

    6-磷酸葡萄糖酶(glucose-6-phosphatase,G6Pase,EC 3.1.3.9)催化6-磷酸葡萄糖水解产生磷酸和葡萄糖,即糖异生途径和糖原分解途径的最后一个限速反应.我们用SMART RACE技术从鲈鱼(Lateolabraxjaponicus)肝脏中克隆了6-磷酸葡萄糖酶催化亚基(glucose-6-phosphatase catalytic subunit,G6PG)基因cDNA序列.该序列全长1651 bp,5’端非翻译区75 bp,3’端非翻译区496 bp,开放阅读框1080bp,可编码一个由359个氨基酸组成的蛋白,该蛋白理论分子量40.45kD、等电点9.30(GenBank登录号:HQ317736.1).氨基酸序列分析表明,鲈鱼G6PC与胡瓜鱼(Osmerus mordax)、翘嘴红鲌(Erythroculter ilishaeformis)、慈鲷(Haplochromis nub ilus)、斑马鱼(Danio rerio)、黑青斑河鲀(Tetraodon nigroviridis)、金头鲷(Sparus aurata)、非洲爪蟾(Xenopus laevis、牛(Bos taurus)、人(Homo sapiens)、小鼠(Mus musculus)及大鼠(Rattus norvegicus)11个物种的同源性达58%以上,其中与胡瓜鱼同源性最高,为85%.RT-PCR分析G6PC基因在鲈鱼肌、心、眼、脑、鳃、肝、肠、肾、脂和脾10个组织中的表达,在肝、肠和肾中有较高的表达,在脑和鳃只有微弱的表达.用基因组步移技术克隆了G6PC基因的5’侧翼区的序列1 243bp,表明该序列含有2个TATA box位点,2个胰岛素作用序列(insulin response sequence,IRS)及C/EBPb、CRE-BP、HNF-3b等潜在的转录因子结合位点.本研究结果表明,鲈鱼G6PC基因在肝、肠和肾中有高表达,其5’侧翼区存在多个转录因子结合位点,该结果为研究G6PC基因的表达调控机制提供了基础资料.%Glucose-6-phosphatase (G6Pase, EC3.1.3.9) catalyzes the hydrolysis of glucose-6-phosphate into glucose, the final step in the gluconeogenic and glycogenolytic pathways. A full-length cDNA of glucose-6-phosphatase catalytic subunit (G6PC) from Lateolabrax japordcus was amplified by SMART RACE method. The cDNA was 1 651 bp in size, with a 75 bp 5'-UTR, 496 bp 3'-UTR and

  5. Effects of Catalytic Subunitαof Protein Phosphatase 2A on Cell Migration of Mouse Embryo Fibroblasts%蛋白磷酸酶2A 催化亚基α在小鼠胚胎成纤维细胞迁移中的作用研究

    Institute of Scientific and Technical Information of China (English)

    王庆华; 王生存; 李斌; 刘春; 吴刘成; 王旭; 邵义祥

    2016-01-01

    利用体外基因敲除技术检测小鼠胚胎成纤维细胞(mouse embryonic fibroblasts,MEFs)周期和迁移能力的变化,探究蛋白磷酸酶2A 的 Cα亚基在 MEFs 细胞迁移过程中的作用。用 Cαfl/fl的纯合子雄鼠与雌鼠1∶2配对,取 E12.5 d 的胚胎制作小鼠胚胎成纤维细胞。利用表达 Cre 重组酶(Ad-Cre-EGFP)以及GFP 荧光蛋白(Ad-EGFP)的腺病毒载体,对 P3代 MEFs 进行感染,分别用 PCR,RT-PCR 和 Western blot方法进行基因型鉴定。同时利用流式分选技术检测感染后 MEFs 的细胞周期的变化,利用细胞划痕试验检测了其细胞迁移能力的变化。结果显示,胰酶消化的方法成功获得了小鼠胚胎成纤维细胞,DNA,RNA 和蛋白水平的鉴定获得了3对3的野生型和基因敲除 MEFs。流式分选发现 Ad-Cre 处理的 MEFs 与 Ad-EG-FP 处理的 MEFs 相比,处于 G2期的细胞比例为30.8%±2.57%,高于 Ad-EGFP MEFs 的23.9%±2.46%,并且细胞碎片的比例也远高于后者。划痕试验表明,Cα亚基缺失后细胞迁移能力下降,12 h 就显著低于对照组。结果表明,腺病毒携带的 Cre 重组酶能够在体外有效地敲除掉 MEFs 中的蛋白磷酸酶2A 的Cα亚基,PP2A Cα亚基的缺失会导致 MEFs 细胞周期倾向于阻滞在 G2期,并会降低细胞迁移的能力。%To investigate the effects of catalytic subunit α of protein phosphatase 2A (PP2A)on cell cycle and cell migration in mouse embryo fibroblasts(MEFs),the mouse embryos were got at E12.5 by mating the heterozygotes of Cαsubunit conditional knockout male and female homozygous mice at the ratio of 1∶2.MEFs were prepared by trypsin digestion and genotyped by PCR,RT-PCR and Western blot to identify the genetic basis of each embryo.Adenovirus associated Cre recombinase and GFP immunofluorescence protein were constructed and delivered to the P3 MEFs to knockout the Cαgene,GFP was used as control

  6. The crystal structure of the complex of Zea mays alpha subunit with a fragment of human beta subunit provides the clue to the architecture of protein kinase CK2 holoenzyme

    DEFF Research Database (Denmark)

    Battistutta, R; Sarno, S; De Moliner, E;

    2000-01-01

    , presents a molecular twofold axis, with each peptide interacting with both alpha chains. In the derived model of the holoenzyme, the regulatory subunits are positioned on the opposite side with respect to the opening of the catalytic sites, that remain accessible to substrates and cosubstrates. The beta......The crystal structure of a complex between the catalytic alpha subunit of Zea mays CK2 and a 23-mer peptide corresponding the C-terminal sequence 181-203 of the human CK2 regulatory beta subunit has been determined at 3.16-A resolution. The complex, composed of two alpha chains and two peptides...... subunit can influence the catalytic activity both directly and by promoting the formation of the alpha2 dimer, in which each alpha chain interacts with the active site of the other. Furthermore, the two active sites are so close in space that they can simultaneously bind and phosphorylate two...

  7. 不同放射敏感性肺腺癌细胞株中DNA-PKcs蛋白的表达情况比较%Comparison of DNA-dependent protein kinase catalytic subunit expression in two lung adenocarcinoma cell lines with different radiosensitivity

    Institute of Scientific and Technical Information of China (English)

    岑伟健; 潘焱; 李伟雄; 杨素清

    2009-01-01

    Objective To investigate DNA-dependent protein kinase catalytic subunit (DNA-PKcs) content and activity in lung adenocarcinoma cell lines and its correlation with radiosensitivity. Methods The content and activity of DNA-PKcs were analyzed in two lung adenocarcinoma cell lines A549 and H1299 by Western blotting and the Signa TECT DNA-PK assay kit. The dose-survival relationship for two cell lines was analyzed using clonogenic formation assay. Results A549 was more radiosensitive than H1299. The survival fractions at 2 Gy (SF2) were 0.7412 in A549 cell line and 0.2473 in H1299 cell line. The content of DNA-PKcs was significantly higher in A549 cells than in H1299 cells (t=10.37, P<0.001). The integrated optical densities were 3.29±0.44 in A549 cells and 0.50±0.17 in H1299 cells. DNA-PKcs activities in A549 and H1299 cells were 8.29±1.37 and 2.47±1.09, respectively, showing a significant difference between them (t=5.76, P=0.005). Conclusion DNA-PKcs is an important factor to affect the radiosensitivity of lung adenocarcinoma cell lines.%目的 通过检测DNA-PKcs在肺腺癌细胞中的表达情况,探讨其与放射敏感性的关系.方法 成克隆实验分别测定肺腺癌细胞株A549、H1299照射后的剂量.存活曲线,Western blotting及DNA-PK活性分析法检测两株细胞中DNA-Pkcs的含量与活性.分析放射敏感性与DNA-PKcs的关系.结果 成克隆实验结果显示:肺腺癌细胞H1299较A549放射更敏感,SF2分别为A549:0.7412,H1299:0.2473.Western-blot显示A549和H1299积分光密度比值分别为:3.29±0.44、0.50±0.17,A549中DNA-PKcs的表达更高(t=10.37,P<0.001).DNA-PKcs活性检测结果为A549:8.29±1.37.H1299:2.47±1.09(t=5.76,P=0.005).结论 放射敏感性不同的肺腺癌细胞株中DNA-Pkcs的表达不同.提示DNA-PKcs可能是影响肺腺癌细胞放射敏感性的重要因素.

  8. Subunit gamma of the oxaloacetate decarboxylase Na(+) pump: interaction with other subunits/domains of the complex and binding site for the Zn(2+) metal ion.

    Science.gov (United States)

    Schmid, Markus; Wild, Markus R; Dahinden, Pius; Dimroth, Peter

    2002-01-29

    The oxaloacetate decarboxylase Na(+) pump of Klebsiella pneumoniae is an enzyme complex composed of the peripheral alpha subunit and the two integral membrane-bound subunits beta and gamma. The alpha subunit consists of the N-terminal carboxyltransferase domain and the C-terminal biotin domain, which are connected by a flexible proline/alanine-rich linker peptide. To probe interactions between the two domains of the alpha subunit and between alpha-subunit domains and the gamma subunit, the relevant polypeptides were synthesized in Escherichia coli and subjected to copurification studies. The two alpha-subunit domains had no distinct affinity toward each other and could, therefore, not be purified as a unit on avidin-sepharose. The two domains reacted together catalytically, however, performing the carboxyl transfer from oxaloacetate to protein-bound biotin. This reaction was enhanced up to 6-fold in the presence of the Zn(2+)-containing gamma subunit. On the basis of copurification with different tagged proteins, the C-terminal biotin domain but not the N-terminal carboxyltransferase domain of the alpha subunit formed a strong complex with the gamma subunit. Upon the mutation of gamma H78 to alanine, the binding affinity to subunit alpha was lost, indicating that this amino acid may be essential for formation of the oxaloacetate decarboxylase enzyme complex. The binding residues for the Zn(2+) metal ion were identified by site-directed and deletion mutagenesis. In the gamma D62A or gamma H77A mutant, the Zn(2+) content of the decarboxylase decreased to 35% or 10% of the wild-type enzyme, respectively. Less than 5% of the Zn(2+) present in the wild-type enzyme was found if the two C-terminal gamma-subunit residues H82 and P83 were deleted. Corresponding with the reduced Zn(2+) contents in these mutants, the oxaloacetate decarboxylase activities were diminished. These results indicate that aspartate 62, histidine 77, and histidine 82 of the gamma subunit are ligands

  9. As rebeliões nas prisões: novos significados a partir da experiência brasileira Prison riots: new meanings after the Brazilian experience

    Directory of Open Access Journals (Sweden)

    Fernando Salla

    2006-12-01

    Full Text Available O objetivo deste artigo é analisar o perfil das rebeliões no sistema carcerário do Brasil, desde a década de 70, recuperando, para tanto, a reflexão produzida sobre estes eventos na França, nos Estados Unidos e no Reino Unido. O artigo tem por argumento principal que as rebeliões nas prisões brasileiras, nos últimos quinze anos, estão associadas tanto às condições degradadas de encarceramento como às deficiências do Estado em exercer o controle sobre o quotidiano prisional, permitindo que grupos criminosos organizados exerçam o poder sobre a massa carcerária, utilizando-se das rebeliões para a eliminação dos inimigos e o fortalecimento de sua posição de domínio frente ao staff prisional.The aim of this article is to examine the profile of riots in Brazil's prison system since the 1970s, reviewing what has been produced on those events in France, the United States, and the United Kingdom. The article's main argument is that riots in Brazilian prisons in the last fifteen years have been associated both to decaying prison conditions and the State's problems to exert control over the prison's everyday life, thus allowing organized crime groups to exert power over the mass of inmates, who use riots to remove enemies and strengthen their position of domination before prison staff.

  10. Mapping the residues of protein kinase CK2 alpha subunit responsible for responsiveness to polyanionic inhibitors

    DEFF Research Database (Denmark)

    Vaglio, P; Sarno, S; Marin, O;

    1996-01-01

    The quadruple mutation of the whole basic cluster, K74KKK77 conserved in the catalytic subunits of protein kinase CK2 and implicated in substrate recognition, not only abolishes inhibition by heparin but even induces with some peptide substrates an up to 5-fold stimulation by heparin in the 0...

  11. Controlling tetramer formation, subunit rotation and DNA ligation during Hin-catalyzed DNA inversion.

    Science.gov (United States)

    Chang, Yong; Johnson, Reid C

    2015-07-27

    Two critical steps controlling serine recombinase activity are the remodeling of dimers into the chemically active synaptic tetramer and the regulation of subunit rotation during DNA exchange. We identify a set of hydrophobic residues within the oligomerization helix that controls these steps by the Hin DNA invertase. Phe105 and Met109 insert into hydrophobic pockets within the catalytic domain of the same subunit to stabilize the inactive dimer conformation. These rotate out of the catalytic domain in the dimer and into the subunit rotation interface of the tetramer. About half of residue 105 and 109 substitutions gain the ability to generate stable synaptic tetramers and/or promote DNA chemistry without activation by the Fis/enhancer element. Phe106 replaces Phe105 in the catalytic domain pocket to stabilize the tetramer conformation. Significantly, many of the residue 105 and 109 substitutions support subunit rotation but impair ligation, implying a defect in rotational pausing at the tetrameric conformer poised for ligation. We propose that a ratchet-like surface involving Phe105, Met109 and Leu112 within the rotation interface functions to gate the subunit rotation reaction. Hydrophobic residues are present in analogous positions in other serine recombinases and likely perform similar functions. PMID:26056171

  12. Protein kinase A regulatory subunit distribution in medulloblastoma

    International Nuclear Information System (INIS)

    Previous studies showed a differential distribution of the four regulatory subunits of cAMP-dependent protein kinases inside the brain, that changed in rodent gliomas: therefore, the distribution of these proteins inside the brain can give information on the functional state of the cells. Our goal was to examine human brain tumors to provide evidence for a differential distribution of protein kinase A in different tumors. The distribution of detergent insoluble regulatory (R1 and R2) and catalytic subunits of cAMP dependent kinases was examined in pediatric brain tumors by immunohistochemistry and fluorescent cAMP analogues binding. R2 is organized in large single dots in medulloblastomas, while it has a different appearance in other tumors. Fluorescent cAMP labelling was observed only in medulloblastoma. A different distribution of cAMP dependent protein kinases has been observed in medulloblastoma

  13. Role of the Rubisco small subunit. Final report for period May 1, 1997--April 30,2000

    Energy Technology Data Exchange (ETDEWEB)

    Spreitzer, Robert J.

    2000-10-04

    CO{sub 2} and O{sub 2} are mutually competitive at the active site of ribulose-1,5-biphosphate (RuBP) carboxylase/oxygenase (Rubisco). Rubisco contains two subunits, each present in eight copies. The 15-kD small subunit is coded by a family of nuclear RbcS genes. Until now, the role of the small subunit in Rubisco structure or catalytic efficiency is not known. Because of other work in eliminating the two RbcS genes in the green algo Chlamydomonas reinhardtii, it is now possible to address questions about the structure-function relationships of the eukaryotic small subunit. There are three specific aims in this project: (1) Alanine scanning mutagenesis is being used to dissect the importance of the {beta}A/{beta}B loop, a feature unique to the eukaryotic small subunit. (2) Random mutagenesis is being used to identify additional residues or regions of the small subunit that are important for holoenzyme assembly and function. (3) Attempts are being made to express foreign small subunits in Chlamydomonas to examine the contribution of small subunits to holoenzyme assembly, catalytic efficiency, and CO{sub 2}/O{sub 2} specificity.

  14. Overexpression of stress-inducible OsBURP16, the β subunit of polygalacturonase 1, decreases pectin content and cell adhesion and increases abiotic stress sensitivity in rice

    OpenAIRE

    Liu, Huanhuan; Ma, Yan; Chen, Na; Guo, Siyi; Liu, Huili; Guo, Xiaoyu; Chong, Kang; Xu, Yunyuan

    2013-01-01

    Polygalacturonase (PG), one of the hydrolases responsible for cell wall pectin degradation, is involved in organ consenescence and biotic stress in plants. PG1 is composed of a catalytic subunit, PG2, and a non-catalytic PG1β subunit. OsBURP16 belongs to the PG1β-like subfamily of BURP-family genes and encodes one putative PG1β subunit precursor in rice (Oryza sativa L.). Transcription of OsBURP16 is induced by cold, salinity and drought stresses, as well as by abscisic acid (ABA) treatment. ...

  15. Comparative genomic analysis of the proteasome β5t subunit gene : implications for the origin and evolution of thymoproteasomes

    OpenAIRE

    Sutoh, Yoichi; Kondo, Mizuho; Ohta, Yuko; Ota, Tatsuya; Tomaru, Utano; Flajnik, Martin F.; Kasahara, Masanori

    2012-01-01

    The thymoproteasome is a recently discovered, specialized form of 20S proteasomes expressed exclusively in the thymic cortex. Although the precise molecular mechanism by which the thymoproteasome exerts its function remains to be elucidated, accumulating evidence indicates that it plays a crucial role in positive selection of T cells. In the present study, we analyzed the evolution of the β5t subunit, a β-type catalytic subunit uniquely present in thymoproteasomes. The gene coding for the β5t...

  16. Comparative genomic analysis of the proteasome β5t subunit gene: implications for the origin and evolution of thymoproteasomes

    OpenAIRE

    Sutoh, Yoichi; Kondo, Mizuho; Ohta, Yuko; Ota, Tatsuya; Tomaru, Utano; Flajnik, Martin F.; Kasahara, Masanori

    2011-01-01

    The thymoproteasome is a recently discovered, specialized form of 20S proteasomes expressed exclusively in the thymic cortex. Although the precise molecular mechanism by which the thymoproteasome exerts its function remains to be elucidated, accumulating evidence indicates that it plays a crucial role in positive selection of T cells. In the present study, we analyzed the evolution of the β5t subunit, a β-type catalytic subunit uniquely present in thymoproteasomes. The gene coding for the β5t...

  17. Défaire et refaire les origines de l’étranger : quand l’ethnographe est pris pour un banni

    Directory of Open Access Journals (Sweden)

    Romain Simenel

    2009-03-01

    Full Text Available Défaire et refaire les origines de l’étranger : quand l’ethnographe est pris pour un banni. En pays Aït Ba’amran, terre d’exil, l’origine de l’étranger qui cherche à s’installer est soumise à un traitement évolutif qui témoigne de son intégration dans le groupe. Qu’il soit juif, chrétien ou musulman, criminel en fuite, réfugié politique ou ethnographe, l’étranger est appréhendé d’office comme un banni, et la question n’est pas de savoir d’où il vient ni ce qu’il était, mais plutôt quelles origines prestigieuses, sur le plan des valeurs musulmanes, lui attribuer. Le devenir des origines de l’étranger se dessine dans le double regard que la société porte sur lui, celui qui vient de l’intérieur, de la sphère privée qu’il a intégré, la famille et les proches voisins, et celui qui vient de l’extérieur, « des gens du souk », l’un et l’autre évoluant de concert. De francaoui à descendant du prophète Mohamed ou de « chrétien » à emblème du haut lieu mystique que j’habitais, mon origine ne cessa d’être défaite et refaite au gré du temps passé sur place, de l’apprentissage de la langue et de l’évolution de mon comportement. Le devenir de mes origines dans le Sud marocain, c’est enfin, en l’absence d’un mariage que je ne voulais pas contracter, l’histoire d’une adoption impossible et d’une latence difficilement supportable socialement pour mes hôtes et pour moi : tout en habitant sous le même toit, je n’étais plus un étranger, mais pas pour autant un consanguin, ni un affin, et en l’absence de ces référents statutaires, mon espace privé se réduisait, telle une peau de chagrin, au fur et à mesure du délitement de tout sentiment de honte (hchouma à l’égard de celui que l’on avait pris pour un banni.Unmaking and remaking the origins of a stranger: when the ethnographer is taken for an outcast. In the region of Ait Ba’amran, land of

  18. Lentivirus-Mediated Short-Hairpin RNA Targeting Protein Phosphatase 4 Regulatory Subunit 1 Inhibits Growth in Breast Cancer

    OpenAIRE

    Qi, Yuying; Hu, Tinghui; Li, Kai; Ye, Renqing; Ye, Zuodong

    2015-01-01

    Purpose Protein phosphatase 4 regulatory subunit 1 (PP4R1), as an interaction partner of the catalytic serine/threonine-protein phosphatase 4 catalytic subunit has been shown to involve in cellular processes and nuclear factor κB signaling. However, the functions of PP4R1 in human breast cancers remain unclear. This study is designed to explore the effect of PP4R1 knockdown on the biological characteristics of breast cancer cells. Methods A lentivirus-mediated short hairpin RNA (shRNA) was de...

  19. Primary structure of the 5 S subunit of transcarboxylase as deduced from the genomic DNA sequence.

    Science.gov (United States)

    Thornton, C G; Kumar, G K; Shenoy, B C; Haase, F C; Phillips, N F; Park, V M; Magner, W J; Hejlik, D P; Wood, H G; Samols, D

    1993-09-13

    Transcarboxylase from Propionibacterium shermanii is a complex biotin-containing enzyme composed of 30 polypeptides of three different types. It is composed of six dimeric outer subunits associated with a central cylindrical hexameric subunit through 12 biotinyl subunits; three outer subunits on each face of the central hexamer. Each outer dimer is termed a 5 S subunit which associates with two biotinyl subunits. The enzyme catalyzes a two-step reaction in which methylmalonyl-CoA and pyruvate form propionyl-CoA and oxalacetate, the 5 S subunit specifically catalyzing one of these reactions. We report here the cloning, sequencing and expression of the monomer of the 5 S subunit. The gene was identified by matching amino acid sequences derived from isolated authentic 5 S peptides with the deduced sequence of an open reading frame present on a cloned P. shermanii genomic fragment known to contain the gene encoding the 1.3 S biotinyl subunit. The cloned 5 S gene encodes a protein of 519 amino acids, M(r) 57,793. The deduced sequence shows regions of extensive homology with that of pyruvate carboxylase and oxalacetate decarboxylase, two enzymes which catalyze the same or reverse reaction. A fragment was subcloned into pUC19 in an orientation such that the 5 S open reading frame could be expressed from the lac promoter of the vector. Crude extracts prepared from these cells contained an immunoreactive band on Western blots which co-migrated with authentic 5 S and were fully active in catalyzing the 5 S partial reaction. We conclude that we have cloned, sequenced and expressed the monomer of the 5 S subunit and that the expressed product is catalytically active. PMID:8365490

  20. Nomenclature for Ion channel Subunits

    OpenAIRE

    Bradley, Jonathan; Frings, Stephan; Yau, King-Wai; Reed, Randall

    2001-01-01

    Presents the nomenclature for ion channel subunits. Role of ion channels in the mediation of visual and olfactory signal transduction; Expression of ion channels in cell types and tissues; Assessment on the nucleotide sensitivity, ion conductance and calcium modulation in heteromers.

  1. Structure of the ATP Synthase Catalytic Complex (F1) from Escherichia coli in an Autoinhibited conformation

    Energy Technology Data Exchange (ETDEWEB)

    G Cingolani; T Duncan

    2011-12-31

    ATP synthase is a membrane-bound rotary motor enzyme that is critical for cellular energy metabolism in all kingdoms of life. Despite conservation of its basic structure and function, autoinhibition by one of its rotary stalk subunits occurs in bacteria and chloroplasts but not in mitochondria. The crystal structure of the ATP synthase catalytic complex (F{sub 1}) from Escherichia coli described here reveals the structural basis for this inhibition. The C-terminal domain of subunit {var_epsilon} adopts a heretofore unknown, highly extended conformation that inserts deeply into the central cavity of the enzyme and engages both rotor and stator subunits in extensive contacts that are incompatible with functional rotation. As a result, the three catalytic subunits are stabilized in a set of conformations and rotational positions distinct from previous F{sub 1} structures.

  2. Cisplatin–DNA adducts inhibit translocation of the Ku subunits of DNA-PK

    OpenAIRE

    Turchi, John J.; Henkels, Karen M.; Zhou, Yun

    2000-01-01

    We have determined the effect of cisplatin–DNA damage on the ability of the DNA-dependent protein kinase (DNA-PK) to interact with duplex DNA molecules in vitro. The Ku DNA binding subunits of DNA-PK display a reduced ability to translocate on duplex DNA containing cisplatin–DNA adducts compared to control, undamaged duplex DNA. The decreased rates of translocation resulted in a decrease in the association of the p460 catalytic subunit of DNA-PK (DNA-PKcs) with the Ku–DNA complex. In addition...

  3. Catalytic distillation structure

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1984-01-01

    Catalytic distillation structure for use in reaction distillation columns, a providing reaction sites and distillation structure and consisting of a catalyst component and a resilient component intimately associated therewith. The resilient component has at least about 70 volume % open space and being present with the catalyst component in an amount such that the catalytic distillation structure consist of at least 10 volume % open space.

  4. Catalytic combustor for hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Mercea, J.; Grecu, E.; Fodor, T.; Kreibik, S.

    1982-01-01

    The performance of catalytic combustors for hydrogen using platinum-supported catalysts is described. Catalytic plates of different sizes were constructed using fibrous and ceramic supports. The temperature distribution as well as the reaction efficiency as a function of the fuel input rate was determined, and a comparison between the performances of different plates is discussed.

  5. Characterization of fimbrial subunits from Bordetella species

    NARCIS (Netherlands)

    Mooi, F.R.; Heide, H.G.J. van der; Avest, A.R. ter; Welinder, K.G.; Livey, I.; Zeijst, B.A.M. van der; Gaastra, W.

    1987-01-01

    Using antisera raised against serotype 2 and 3 fimbrial subunits from Bordetella pertussis, serologically related polypeptides were detected in Bordetella bronchiseptica, Bordetella parapertussis and Bordetella avium strains. The two B. pertussis fimbrial subunits, and three of the serologically rel

  6. The beta subunit of casein kinase II

    DEFF Research Database (Denmark)

    Boldyreff, B; Piontek, K; Schmidt-Spaniol, I;

    1991-01-01

    cDNAs encoding the beta subunit of pig and mouse CKII were isolated. The porcine cDNA was expressed as a fusion protein in Escherichia coli and used for the production of anti-CKII-beta subunit specific antibodies.......cDNAs encoding the beta subunit of pig and mouse CKII were isolated. The porcine cDNA was expressed as a fusion protein in Escherichia coli and used for the production of anti-CKII-beta subunit specific antibodies....

  7. Targeting the Large Subunit of Human Ribonucleotide Reductase for Cancer Chemotherapy

    Directory of Open Access Journals (Sweden)

    Prem Singh Kaushal

    2011-10-01

    Full Text Available Ribonucleotide reductase (RR is a crucial enzyme in de novo DNA synthesis, where it catalyses the rate determining step of dNTP synthesis. RRs consist of a large subunit called RR1 (α, that contains two allosteric sites and one catalytic site, and a small subunit called RR2 (β, which houses a tyrosyl free radical essential for initiating catalysis. The active form of mammalian RR is an anbm hetero oligomer. RR inhibitors are cytotoxic to proliferating cancer cells. In this brief review we will discuss the three classes of RR, the catalytic mechanism of RR, the regulation of the dNTP pool, the substrate selection, the allosteric activation, inactivation by ATP and dATP, and the nucleoside drugs that target RR. We will also discuss possible strategies for developing a new class of drugs that disrupts the RR assembly.

  8. Catalytic distillation process

    Science.gov (United States)

    Smith, Jr., Lawrence A.

    1982-01-01

    A method for conducting chemical reactions and fractionation of the reaction mixture comprising feeding reactants to a distillation column reactor into a feed zone and concurrently contacting the reactants with a fixed bed catalytic packing to concurrently carry out the reaction and fractionate the reaction mixture. For example, a method for preparing methyl tertiary butyl ether in high purity from a mixed feed stream of isobutene and normal butene comprising feeding the mixed feed stream to a distillation column reactor into a feed zone at the lower end of a distillation reaction zone, and methanol into the upper end of said distillation reaction zone, which is packed with a properly supported cationic ion exchange resin, contacting the C.sub.4 feed and methanol with the catalytic distillation packing to react methanol and isobutene, and concurrently fractionating the ether from the column below the catalytic zone and removing normal butene overhead above the catalytic zone.

  9. Catalytic Functions of Standards

    NARCIS (Netherlands)

    K. Blind (Knut)

    2009-01-01

    textabstractThe three different areas and the examples have illustrated several catalytic functions of standards for innovation. First, the standardisation process reduces the time to market of inventions, research results and innovative technologies. Second, standards themselves promote the diffusi

  10. Modelo preditivo do uso de cocaína em prisões do Estado do Rio de Janeiro Predictive model for cocaine use in prisons in Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Márcia Lazaro de Carvalho

    2005-10-01

    Full Text Available OBJETIVO: Identificar variáveis preditoras e grupos mais vulneráveis ao uso de cocaína em prisão. MÉTODOS: Foram selecionados 376 presos com história de uso de cocaína em prisão (casos e 938 presos sem história de uso de cocaína na vida (controles, que cumpriam pena no sistema penitenciário do Rio de Janeiro em 1998. A análise considerou as variáveis de exposição em três níveis de hierarquia: distal, intermediário e proximal. Na análise bivariada utilizou-se regressão logística e na multivariada, regressão hierarquizada, resultando em valores de odds ratio. RESULTADOS: As variáveis associadas ao uso de cocaína na prisão, no nível proximal, foram uso de álcool e maconha e tempo de reclusão em anos. O efeito das variáveis de vulnerabilidade social (nível distal é intermediado pelas variáveis dos níveis seguintes. Considerando apenas os níveis distal e intermediário, o uso de maconha antes de ser preso (OR=4,50; IC 95%: 3,17-6,41 e o fato de ter cometido delito para obter droga (OR=2,96; IC 95%: 1,79-4,90 são as mais fortemente associadas ao desfecho. Para cada ano a mais que se passa na prisão, a chance de usar cocaína aumenta em 13% (OR=1,13; IC 95%: 1,06-1,21. CONCLUSÕES: Considerando os níveis distal e intermediário, o uso de maconha antes da prisão e delito para obtenção de droga foram as variáveis com maior poder de predição. O modelo final revelou o uso de álcool, de maconha na prisão e o tempo de cumprimento de pena são importantes preditores do desfecho. O ambiente carcerário aparece como fator estimulante da continuidade do uso de drogas.OBJECTIVE: To identify predictors of and groups vulnerable to cocaine use in prison. METHODS: We selected 376 inmates with history of cocaine use in prison (cases and 938 inmates with no history of drug use (controls serving sentences in the Rio de Janeiro State prison system in 1998. The analysis included exposure variables divided into three

  11. Catalytic ignition of light hydrocarbons

    Institute of Scientific and Technical Information of China (English)

    K. L. Hohn; C.-C. Huang; C. Cao

    2009-01-01

    Catalytic ignition refers to phenomenon where sufficient energy is released from a catalytic reaction to maintain further reaction without additional extemai heating. This phenomenon is important in the development of catalytic combustion and catalytic partial oxidation processes, both of which have received extensive attention in recent years. In addition, catalytic ignition studies provide experimental data which can be used to test theoretical hydrocarbon oxidation models. For these reasons, catalytic ignition has been frequently studied. This review summarizes the experimental methods used to study catalytic ignition of light hydrocarbons and describes the experimental and theoretical results obtained related to catalytic ignition. The role of catalyst metal, fuel and fuel concentration, and catalyst state in catalytic ignition are examined, and some conclusions are drawn on the mechanism of catalytic ignition.

  12. Cloning and characterization of ADP-glucose pyrophosphorylase small subunit gene in Cyperus esculentus (yellow nutsedge).

    Science.gov (United States)

    Cheng, C; Hu, J; Zhi, Y; Su, J J; Zhang, X K; Huang, B Q

    2015-01-01

    ADP-glucose pyrophosphorylase (ADPGlcPPase) controls the first committed step of starch synthesis by catalyzing the biosynthesis of ADP-glucose from glucose-phosphate and ATP. It is a tetrameric protein consisting of two small and two large subunits. The small subunits have a catalytic function, while the large subunits regulate the enzyme activity. Cyperus esculentus (yellow nutsedge) is a perennial C4 plant grown from rhizomes and tubers. Previous studies on yellow nutsedge have mostly focused on the morphology and cultivation of tubers, their application in food, and biochemical analyses of the tubers. In this study, the gene encoding the ADPGlcPPase small subunit (CeAGPS) in yellow nutsedge was cloned and characterized. The full-length CeAGPS cDNA sequence contained an 81-bp 5'-untranslated region (UTR), a 188-bp 3'-UTR, and a 1539-bp open reading frame encoding 512-amino acid residues. The genomic sequence of CeAGPS comprises a nine exon-eight intron structure similar to the previously reported cotton and Arabidopsis thaliana AGPS genes. The deduced translation product of the CeAGPS gene contained a well-conserved catalytic domain and regulatory elements typical of plant AGPS. Reverse transcriptase polymerase chain reaction amplification of the target gene in various plant parts using gene-specific primers indicated that the expression of CeAGPS was most abundant in the tuber, and relatively lower in nutsedge roots. PMID:26782478

  13. Structural and biochemical characterization of human PR70 in isolation and in complex with the scaffolding subunit of protein phosphatase 2A.

    Directory of Open Access Journals (Sweden)

    Rebecca Dovega

    Full Text Available Protein Phosphatase 2A (PP2A is a major Ser/Thr phosphatase involved in the regulation of various cellular processes. PP2A assembles into diverse trimeric holoenzymes, which consist of a scaffolding (A subunit, a catalytic (C subunit and various regulatory (B subunits. Here we report a 2.0 Å crystal structure of the free B''/PR70 subunit and a SAXS model of an A/PR70 complex. The crystal structure of B''/PR70 reveals a two domain elongated structure with two Ca2+ binding EF-hands. Furthermore, we have characterized the interaction of both binding partner and their calcium dependency using biophysical techniques. Ca2+ biophysical studies with Circular Dichroism showed that the two EF-hands display different affinities to Ca2+. In the absence of the catalytic C-subunit, the scaffolding A-subunit remains highly mobile and flexible even in the presence of the B''/PR70 subunit as judged by SAXS. Isothermal Titration Calorimetry studies and SAXS data support that PR70 and the A-subunit have high affinity to each other. This study provides additional knowledge about the structural basis for the function of B'' containing holoenzymes.

  14. Phosphorylation of the regulatory beta-subunit of protein kinase CK2 by checkpoint kinase Chk1: identification of the in vitro CK2beta phosphorylation site

    DEFF Research Database (Denmark)

    Kristensen, Lars P; Larsen, Martin Røssel; Højrup, Peter;

    2004-01-01

    The regulatory beta-subunit of protein kinase CK2 mediates the formation of the CK2 tetrameric form and it has functions independent of CK2 catalytic subunit through interaction with several intracellular proteins. Recently, we have shown that CK2beta associates with the human checkpoint kinase Chk...... by the modification of Thr213 but it does require the presence of an active Chk1 kinase....

  15. Catalytic coherence transformations

    Science.gov (United States)

    Bu, Kaifeng; Singh, Uttam; Wu, Junde

    2016-04-01

    Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and stochastic catalytic coherence transformations between a pair of pure quantum states. In particular, we show that the simultaneous decrease of a family of Rényi entropies of the diagonal parts of the states under consideration is a necessary and sufficient condition for the deterministic catalytic coherence transformations. Similarly, for stochastic catalytic coherence transformations we find the necessary and sufficient conditions for achieving a higher optimal probability of conversion. We thus completely characterize the coherence transformations among pure quantum states under incoherent operations. We give numerous examples to elaborate our results. We also explore the possibility of the same system acting as a catalyst for itself and find that indeed self-catalysis is possible. Further, for the cases where no catalytic coherence transformation is possible we provide entanglement-assisted coherence transformations and find the necessary and sufficient conditions for such transformations.

  16. Characterisation of the tryptophan synthase alpha subunit in maize

    Directory of Open Access Journals (Sweden)

    Gierl Alfons

    2008-04-01

    Full Text Available Abstract Background In bacteria, such as Salmonella typhimurium, tryptophan is synthesized from indole-3-glycerole phosphate (IGP by a tryptophan synthase αββα heterotetramer. Plants have evolved multiple α (TSA and β (TSB homologs, which have probably diverged in biological function and their ability of subunit interaction. There is some evidence for a tryptophan synthase (TS complex in Arabidopsis. On the other hand maize (Zea mays expresses the TSA-homologs BX1 and IGL that efficiently cleave IGP, independent of interaction with TSB. Results In order to clarify, how tryptophan is synthesized in maize, two TSA homologs, hitherto uncharacterized ZmTSA and ZmTSAlike, were functionally analyzed. ZmTSA is localized in plastids, the major site of tryptophan biosynthesis in plants. It catalyzes the tryptophan synthase α-reaction (cleavage of IGP, and forms a tryptophan synthase complex with ZmTSB1 in vitro. The catalytic efficiency of the α-reaction is strongly enhanced upon complex formation. A 160 kD tryptophan synthase complex was partially purified from maize leaves and ZmTSA was identified as native α-subunit of this complex by mass spectrometry. ZmTSAlike, for which no in vitro activity was detected, is localized in the cytosol. ZmTSAlike, BX1, and IGL were not detectable in the native tryptophan synthase complex in leaves. Conclusion It was demonstrated in vivo and in vitro that maize forms a tryptophan synthase complex and ZmTSA functions as α-subunit in this complex.

  17. Structural analysis of the α subunit of Na(+)/K(+) ATPase genes in invertebrates.

    Science.gov (United States)

    Thabet, Rahma; Rouault, J-D; Ayadi, Habib; Leignel, Vincent

    2016-01-01

    The Na(+)/K(+) ATPase is a ubiquitous pump coordinating the transport of Na(+) and K(+) across the membrane of cells and its role is fundamental to cellular functions. It is heteromer in eukaryotes including two or three subunits (α, β and γ which is specific to the vertebrates). The catalytic functions of the enzyme have been attributed to the α subunit. Several complete α protein sequences are available, but only few gene structures were characterized. We identified the genomic sequences coding the α-subunit of the Na(+)/K(+) ATPase, from the whole-genome shotgun contigs (WGS), NCBI Genomes (chromosome), Genomic Survey Sequences (GSS) and High Throughput Genomic Sequences (HTGS) databases across distinct phyla. One copy of the α subunit gene was found in Annelida, Arthropoda, Cnidaria, Echinodermata, Hemichordata, Mollusca, Placozoa, Porifera, Platyhelminthes, Urochordata, but the nematodes seem to possess 2 to 4 copies. The number of introns varied from 0 (Platyhelminthes) to 26 (Porifera); and their localization and length are also highly variable. Molecular phylogenies (Maximum Likelihood and Maximum Parsimony methods) showed some clusters constituted by (Chordata/(Echinodermata/Hemichordata)) or (Plathelminthes/(Annelida/Mollusca)) and a basal position for Porifera. These structural analyses increase our knowledge about the evolutionary events of the α subunit genes in the invertebrates. PMID:26812300

  18. Risk capital allocation with autonomous subunits

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Smilgins, Aleksandrs

    2016-01-01

    Risk capital allocation problems have been widely discussed in the academic literature. We consider a set of independent subunits collaborating in order to reduce risk: that is, when subunit portfolios are merged a diversification benefit arises and the risk of the group as a whole is smaller than...

  19. Catalytic Conversion of Biofuels

    DEFF Research Database (Denmark)

    Jørgensen, Betina

    This thesis describes the catalytic conversion of bioethanol into higher value chemicals. The motivation has been the unavoidable coming depletion of the fossil resources. The thesis is focused on two ways of utilising ethanol; the steam reforming of ethanol to form hydrogen and the partial oxida...

  20. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

    The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.

  1. Catalytic efficiency of designed catalytic proteins.

    Science.gov (United States)

    Korendovych, Ivan V; DeGrado, William F

    2014-08-01

    The de novo design of catalysts that mimic the affinity and specificity of natural enzymes remains one of the Holy Grails of chemistry. Despite decades of concerted effort we are still unable to design catalysts as efficient as enzymes. Here we critically evaluate approaches to (re)design of novel catalytic function in proteins using two test cases: Kemp elimination and ester hydrolysis. We show that the degree of success thus far has been modest when the rate enhancements seen for the designed proteins are compared with the rate enhancements by small molecule catalysts in solvents with properties similar to the active site. Nevertheless, there are reasons for optimism: the design methods are ever improving and the resulting catalyst can be efficiently improved using directed evolution.

  2. Organization of Subunits in the Membrane Domain of the Bovine F-ATPase Revealed by Covalent Cross-linking*

    Science.gov (United States)

    Lee, Jennifer; Ding, ShuJing; Walpole, Thomas B.; Holding, Andrew N.; Montgomery, Martin G.; Fearnley, Ian M.; Walker, John E.

    2015-01-01

    The F-ATPase in bovine mitochondria is a membrane-bound complex of about 30 subunits of 18 different kinds. Currently, ∼85% of its structure is known. The enzyme has a membrane extrinsic catalytic domain, and a membrane intrinsic domain where the turning of the enzyme's rotor is generated from the transmembrane proton-motive force. The domains are linked by central and peripheral stalks. The central stalk and a hydrophobic ring of c-subunits in the membrane domain constitute the enzyme's rotor. The external surface of the catalytic domain and membrane subunit a are linked by the peripheral stalk, holding them static relative to the rotor. The membrane domain contains six additional subunits named ATP8, e, f, g, DAPIT (diabetes-associated protein in insulin-sensitive tissues), and 6.8PL (6.8-kDa proteolipid), each with a single predicted transmembrane α-helix, but their orientation and topography are unknown. Mutations in ATP8 uncouple the enzyme and interfere with its assembly, but its roles and the roles of the other five subunits are largely unknown. We have reacted accessible amino groups in the enzyme with bifunctional cross-linking agents and identified the linked residues. Cross-links involving the supernumerary subunits, where the structures are not known, show that the C terminus of ATP8 extends ∼70 Å from the membrane into the peripheral stalk and that the N termini of the other supernumerary subunits are on the same side of the membrane, probably in the mitochondrial matrix. These experiments contribute significantly toward building up a complete structural picture of the F-ATPase. PMID:25851905

  3. Crime-prisão-liberdade-crime: o círculo perverso da reincidência no crime Crime-jail-free (liberty-crime: the wicked circle the crime reincidence

    Directory of Open Access Journals (Sweden)

    Angelita Rangel Ferreira

    2011-09-01

    Full Text Available Esse artigo objetiva identificar, a partir das vozes e visões daqueles que a protagonizam - homens e mulheres privados de liberdade no Centro de Remanejamento do Sistema Prisional (Ceresp de Ipatinga (MG -, os fatores sociais, políticos, econômicos, históricos e culturais que os impelem a reproduzir o percurso crime-prisão-liberdade-crime, num círculo vicioso sem fim. O que importa é realizar tal análise sem, contudo, se eximir de responsabilidade analítica, teórica e política.This article aims to identify, from the voices and visions of those who are protagonists - men and women deprived of liberty in the Relocation Center of Prisons (Ceresp Ipatinga/MG - the social, political, economic, historical and cultural factors that impel them to reproduce the route crime-jail-free (liberty-crime, in an endless vicious circle. What matters is to perform the analysis, without, exempt (shunning an analytical, theoretical and political responsibility.

  4. Clínica e estratégias de resistência: perspectivas para o trabalho do psicólogo em prisões Clinical psychology and strategies of resistance: perspectives of a psychologist's work in prisons

    Directory of Open Access Journals (Sweden)

    Cristina Rauter

    2007-08-01

    Full Text Available Este trabalho é um estudo sobre a instituição prisional tomada como um dos componentes do dispositivo da criminalidade. Esse dispositivo de controle social é analisado como central no capitalismo contemporâneo, engendrando múltiplos efeitos mortificadores. Observa-se, no que diz respeito ao trabalho do psicólogo nas prisões, a decadência do discurso da recuperação e o fortalecimento de práticas coercitivas e punitivas. Por outro lado, o trabalho do psicólogo pode se inserir entre as estratégias de resistência e de vitalização.This work is a study about penal institutions understood as a component of the "criminality device". The analysis of this social control device is carried out with the comprehension that it is a central aspect of contemporary capitalism, generating multiple lethal effects. Considering the work of psychologists in prisons, the decadence of the discourse of recuperation and the strengthening of coercive and punitive strategies was observed. On the other hand, a psychologist's work can be inserted between the strategies of resistance and vitalization.

  5. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  6. Subunit architecture of general transcription factor TFIIH

    OpenAIRE

    Gibbons, Brian J.; Brignole, Edward J; Azubel, Maia; Murakami, Kenji; Voss, Neil R; Bushnell, David A.; Asturias, Francisco J; Kornberg, Roger D.

    2012-01-01

    Structures of complete 10-subunit yeast TFIIH and of a nested set of subcomplexes, containing 5, 6, and 7 subunits, have been determined by electron microscopy (EM) and 3D reconstruction. Consistency among all the structures establishes the location of the “minimal core” subunits (Ssl1, Tfb1, Tfb2, Tfb4, and Tfb5), and additional densities can be specifically attributed to Rad3, Ssl2, and the TFIIK trimer. These results can be further interpreted by placement of previous X-ray structures into...

  7. Cleft Lip Repair: The Hybrid Subunit Method.

    Science.gov (United States)

    Tollefson, Travis T

    2016-04-01

    The unilateral cleft lip repair is one of the most rewarding and challenging of plastic surgery procedures. Surgeons have introduced a variety of straight line, geometric, and rotation-advancement designs, while in practice the majority of North American surgeons have been using hybrids of the rotation-advancement techniques. The anatomic subunit approach was introduced in 2005 by Fisher and has gained popularity, with early adopters of the design touting its simplicity and effectiveness. The objectives of this article are to summarize the basic tenets of respecting the philtral subunit, accurate measurement and planning, and tips for transitioning to this subunit approach.

  8. A catalytic cracking process

    Energy Technology Data Exchange (ETDEWEB)

    Degnan, T.F.; Helton, T.E.

    1995-07-20

    Heavy oils are subjected to catalytic cracking in the absence of added hydrogen using a catalyst containing a zeolite having the structure of ZSM-12 and a large-pore crystalline zeolite having a Constraint Index less than about 1. The process is able to effect a bulk conversion of the oil at the same time yielding a higher octane gasoline and increased light olefin content. (author)

  9. 体重指数与谷氨酰半胱氨酸合成酶催化亚基基因多态性的交互作用对女性乳腺癌风险的影响%Interaction of body mass index and a polymorphism in gene of catalytic subunit of glutamate cysteine ligase on breast cancer risk among Chinese women

    Institute of Scientific and Technical Information of China (English)

    林威; 唐录英; 岑玉玲; 林颖; 苏逢锡; 贾卫华; 任泽舫

    2013-01-01

    目的 探讨谷氨酰半胱氨酸合成酶催化亚基(GCLC)rs17883901多态性位点对BMI与乳腺癌关联的影响.方法 于2008年10月至2010年6月对中山大学3所附属医院新诊断的839例乳腺癌患者(病例组)在接受治疗前及同时期863名年龄频数匹配的对照(对照组)进行问卷调查和收集血样;采用基质辅助激光解吸-飞行时间质谱仪(MALDI-TOF-MS),在Sequenom平台检测rs17883901位点基因型;采用非条件logistic回归分析计算BMI和GCLC与乳腺癌关联的OR值及其95%CI.结果 (1)病例组和对照组接受调查时当前的BMI、20岁时的BMI和GCLCrs17883901位点分布的差异均无统计学意义(P=0.44、0.52和0.47);(2)未发现当前的BMI与绝经前及绝经后乳腺癌风险相关,20岁时BMI为18.5~22.9 kg/m2可降低绝经前乳腺癌风险(OR=0.69,95%CI:0.48~1.00),而未发现其与绝经后乳腺癌风险相关;(3)在GCLC rs17883901位点突变型CT/TT人群中,当前的BMI≥25 kg/m2显著增加乳腺癌风险(OR=1.91,95%CI:1.09~ 3.36),而20岁时BMI为18.5 ~ 22.9 kg/m2与降低乳腺癌风险有关(OR=0.56,95%CI:0.31 ~ 0.99).当前的BMI与GCLC基因多态性对乳腺癌发生风险存在交互作用(P=0.043),而20岁时的BMI与GCLC交互项无统计学意义(P=0.15).结论 20岁时增加BMI可能是绝经前乳腺癌的保护因素;GCLCrs17883901位点本身与乳腺癌发生风险无显著关联,但其变异基因型可使当前的肥胖状态(BMI≥25 kg/m2)显著增加乳腺癌发生风险.%Objective To investigate the interaction of body mass index (BMI) and a single nucleotide polymorphism (SNP,rs17883901) in catalytic subunit of glutamate-cysteine ligase (GCLC) on breast cancer risk.Methods A total of 839 women with incident breast cancer and 863 age-matched controls without cancer were recruited at the same period in three affiliated hospitals of Sun Yat-sen University in Guangzhou from October 2008 to June 2010.GCLC rs17883901 was genotyped

  10. Autosomal-Recessive Mutations in the tRNA Splicing Endonuclease Subunit TSEN15 Cause Pontocerebellar Hypoplasia and Progressive Microcephaly.

    Science.gov (United States)

    Breuss, Martin W; Sultan, Tipu; James, Kiely N; Rosti, Rasim O; Scott, Eric; Musaev, Damir; Furia, Bansri; Reis, André; Sticht, Heinrich; Al-Owain, Mohammed; Alkuraya, Fowzan S; Reuter, Miriam S; Abou Jamra, Rami; Trotta, Christopher R; Gleeson, Joseph G

    2016-07-01

    The tRNA splicing endonuclease is a highly evolutionarily conserved protein complex, involved in the cleavage of intron-containing tRNAs. In human it consists of the catalytic subunits TSEN2 and TSEN34, as well as the non-catalytic TSEN54 and TSEN15. Recessive mutations in the corresponding genes of the first three are known to cause pontocerebellar hypoplasia (PCH) types 2A-C, 4, and 5. Here, we report three homozygous TSEN15 variants that cause a milder version of PCH2. The affected individuals showed progressive microcephaly, delayed developmental milestones, intellectual disability, and, in two out of four cases, epilepsy. None, however, displayed the central visual failure seen in PCH case subjects where other subunits of the TSEN are mutated, and only one was affected by the extensive motor defects that are typical in other forms of PCH2. The three amino acid substitutions impacted the protein level of TSEN15 and the stoichiometry of the interacting subunits in different ways, but all resulted in an almost complete loss of in vitro tRNA cleavage activity. Taken together, our results demonstrate that mutations in any known subunit of the TSEN complex can cause PCH and progressive microcephaly, emphasizing the importance of its function during brain development. PMID:27392077

  11. Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A

    Directory of Open Access Journals (Sweden)

    Janssens Veerle

    2008-08-01

    Full Text Available Abstract Background Protein phosphatase 2A (PP2A is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specificity. Three B-type subunit families have been identified: PR55/B, PR61/B' and PR72/B", of which the latter is currently the least characterised. Results We deduced the sequences and genomic organisation of the different murine PR72/B" isoforms: three genes encode nine isoforms, five of which are abundantly expressed and give rise to genuine PP2A subunits. Thereby, one novel subunit was identified. Using Northern blotting, we examined the tissue-specific and developmental expression of these subunits. All subunits are highly expressed in heart, suggesting an important cardiac function. Immunohistochemical analysis revealed a striated expression pattern of PR72 and PR130 in heart and skeletal muscle, but not in bladder smooth muscle. The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities. Conclusion In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue. We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins. Our results provide a platform for the future generation of PR72/B" knockout mice.

  12. Novel Catalytic Membrane Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stuart Nemser, PhD

    2010-10-01

    There are many industrial catalytic organic reversible reactions with amines or alcohols that have water as one of the products. Many of these reactions are homogeneously catalyzed. In all cases removal of water facilitates the reaction and produces more of the desired chemical product. By shifting the reaction to right we produce more chemical product with little or no additional capital investment. Many of these reactions can also relate to bioprocesses. Given the large number of water-organic compound separations achievable and the ability of the Compact Membrane Systems, Inc. (CMS) perfluoro membranes to withstand these harsh operating conditions, this is an ideal demonstration system for the water-of-reaction removal using a membrane reactor. Enhanced reaction synthesis is consistent with the DOE objective to lower the energy intensity of U.S. industry 25% by 2017 in accord with the Energy Policy Act of 2005 and to improve the United States manufacturing competitiveness. The objective of this program is to develop the platform technology for enhancing homogeneous catalytic chemical syntheses.

  13. An Alternate Splicing Variant of the Human Telomerase Catalytic Subunit Inhibits Telomerase Activity

    Directory of Open Access Journals (Sweden)

    Xiaoming Yi

    2000-09-01

    Full Text Available Telomerase, a cellular reverse transcriptase, adds telomeric repeats to chromosome ends. In normal human somatic cells, telomerase is repressed and telomeres progressively shorten, leading to proliferative senescence. Introduction of the telomerase (hTERT cDNA is sufficient to produce telomerase activity and immortalize normal human cells, suggesting that the repression of telomerase activity is transcriptional. The telomerase transcript has been shown to have at least six alternate splicing sites (four insertion sites and two deletion sites, and variants containing both or either of the deletion sites are present during development and in a panel of cancer cell lines we surveyed. One deletion (β site and all four insertions cause premature translation terminations, whereas the other deletion (α site is 36 by and lies within reverse transcriptase (RT motif A, suggesting that this deletion variant may be a candidate as a dominant-negative inhibitor of telomerase. We have cloned three alternately spliced hTERT variants that contain the α,β or both α and,β deletion sites. These alternate splicing variants along with empty vector and wild-type hTERT were introduced into normal human fibroblasts and several telomerase-positive immortal and tumor cell lines. Expression of the α site deletion variant (hTERT α− construct was confirmed by Western blotting. We found that none of the three alternate splicing variants reconstitutes telomerase activity in fibroblasts. However, hTERT α− inhibits telomerase activities in telomerase-positive cells, causes telomere shortening and eventually cell death. This alternately spliced dominant-negative variant may be important in understanding telomerase regulation during development, differentiation and in cancer progression.

  14. Absence of telomerase activity and telomerase catalytic subunit mRNA in melanocyte cultures

    OpenAIRE

    Dhaene, K.; Vancoillie, G; Lambert, J.; Naeyaert, J M; Van Marck, E

    2000-01-01

    The classic model of activation of telomerase, for which activity has been found in most cancers including cutaneous malignant melanoma (CMM), dictates that enzyme activity is generated by pathological reactivation of telomerase in telomerase-negative somatic cells. However, recent data demonstrated physiological up-regulation in some normal cell types when established as proliferating cultures, indicating that, in some cancer types, telomerase is expressed by the process of up-regulation in ...

  15. Genetic diagnostic test of hepatocellular carcinoma by telomerase catalytic subunit mRNA.

    Science.gov (United States)

    Wada, E; Hisatomi, H; Moritoyo, T; Kanamaru, T; Hikiji, K

    1998-01-01

    This study investigated the relationship between telomerase activity and telomere length and between telomerase reverse transcriptase (hTERT) mRNA and telomere length. Both cancerous and non-cancerous tissues were studied in individuals with hepatic carcinoma. In this study, the telomere length in HCC livers had a wide range, no clear significant correlation was found between hTERT mRNA and telomere length. Telomerase activity was more strongly correlated with hTERT mRNA than with telomere length. The correlation between hTERT mRNA and telomerase activity shown here indicates that hTERT mRNA has potential for cancer diagnosis. PMID:9769378

  16. HYDROGEN TRANSFER IN CATALYTIC CRACKING

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Hydrogen transfer is an important secondary reaction of catalytic cracking reactions, which affects product yield distribution and product quality. It is an exothermic reaction with low activation energy around 43.3 kJ/mol. Catalyst properties and operation parameters in catalytic cracking greatly influence the hydrogen transfer reaction. Satisfactory results are expected through careful selection of proper catalysts and operation conditions.

  17. Liposome-Based Adjuvants for Subunit Vaccines

    DEFF Research Database (Denmark)

    Tandrup Schmidt, Signe; Foged, Camilla; Rades, Thomas

    2016-01-01

    The development of subunit vaccines has become very attractive in recent years due to their superior safety profiles as compared to traditional vaccines based on live attenuated or whole inactivated pathogens, and there is an unmet medical need for improved vaccines and vaccines against pathogens...... for which no effective vaccines exist. The subunit vaccine technology exploits pathogen subunits as antigens, e.g., recombinant proteins or synthetic peptides, allowing for highly specific immune responses against the pathogens. However, such antigens are usually not sufficiently immunogenic to induce...... been licensed for use in human vaccines, and they mainly stimulate humoral immunity. Thus, there is an unmet demand for the development of safe and efficient adjuvant systems that can also stimulate cell-mediated immunity (CMI). Adjuvants constitute a heterogeneous group of compounds, which can broadly...

  18. Bifunctional catalytic electrode

    Science.gov (United States)

    Cisar, Alan (Inventor); Murphy, Oliver J. (Inventor); Clarke, Eric (Inventor)

    2005-01-01

    The present invention relates to an oxygen electrode for a unitized regenerative hydrogen-oxygen fuel cell and the unitized regenerative fuel cell having the oxygen electrode. The oxygen electrode contains components electrocatalytically active for the evolution of oxygen from water and the reduction of oxygen to water, and has a structure that supports the flow of both water and gases between the catalytically active surface and a flow field or electrode chamber for bulk flow of the fluids. The electrode has an electrocatalyst layer and a diffusion backing layer interspersed with hydrophilic and hydrophobic regions. The diffusion backing layer consists of a metal core having gas diffusion structures bonded to the metal core.

  19. Catalytic quantum error correction

    CERN Document Server

    Brun, T; Hsieh, M H; Brun, Todd; Devetak, Igor; Hsieh, Min-Hsiu

    2006-01-01

    We develop the theory of entanglement-assisted quantum error correcting (EAQEC) codes, a generalization of the stabilizer formalism to the setting in which the sender and receiver have access to pre-shared entanglement. Conventional stabilizer codes are equivalent to dual-containing symplectic codes. In contrast, EAQEC codes do not require the dual-containing condition, which greatly simplifies their construction. We show how any quaternary classical code can be made into a EAQEC code. In particular, efficient modern codes, like LDPC codes, which attain the Shannon capacity, can be made into EAQEC codes attaining the hashing bound. In a quantum computation setting, EAQEC codes give rise to catalytic quantum codes which maintain a region of inherited noiseless qubits. We also give an alternative construction of EAQEC codes by making classical entanglement assisted codes coherent.

  20. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  1. Protein phosphatase 2A regulatory subunit B56α limits phosphatase activity in the heart.

    Science.gov (United States)

    Little, Sean C; Curran, Jerry; Makara, Michael A; Kline, Crystal F; Ho, Hsiang-Ting; Xu, Zhaobin; Wu, Xiangqiong; Polina, Iuliia; Musa, Hassan; Meadows, Allison M; Carnes, Cynthia A; Biesiadecki, Brandon J; Davis, Jonathan P; Weisleder, Noah; Györke, Sandor; Wehrens, Xander H; Hund, Thomas J; Mohler, Peter J

    2015-07-21

    Protein phosphatase 2A (PP2A) is a serine/threonine-selective holoenzyme composed of a catalytic, scaffolding, and regulatory subunit. In the heart, PP2A activity is requisite for cardiac excitation-contraction coupling and central in adrenergic signaling. We found that mice deficient in the PP2A regulatory subunit B56α (1 of 13 regulatory subunits) had altered PP2A signaling in the heart that was associated with changes in cardiac physiology, suggesting that the B56α regulatory subunit had an autoinhibitory role that suppressed excess PP2A activity. The increase in PP2A activity in the mice with reduced B56α expression resulted in slower heart rates and increased heart rate variability, conduction defects, and increased sensitivity of heart rate to parasympathetic agonists. Increased PP2A activity in B56α(+/-) myocytes resulted in reduced Ca(2+) waves and sparks, which was associated with decreased phosphorylation (and thus decreased activation) of the ryanodine receptor RyR2, an ion channel on intracellular membranes that is involved in Ca(2+) regulation in cardiomyocytes. In line with an autoinhibitory role for B56α, in vivo expression of B56α in the absence of altered abundance of other PP2A subunits decreased basal phosphatase activity. Consequently, in vivo expression of B56α suppressed parasympathetic regulation of heart rate and increased RyR2 phosphorylation in cardiomyocytes. These data show that an integral component of the PP2A holoenzyme has an important inhibitory role in controlling PP2A enzyme activity in the heart.

  2. TFB2 is a transient component of the catalytic site of the human mitochondrial RNA polymerase

    OpenAIRE

    Sologub, Marina; Litonin, Dmitry; Anikin, Michael; Mustaev, Arkady; Temiakov, Dmitry

    2009-01-01

    Transcription in human mitochondria is carried out by a single-subunit, T7-like RNA polymerase assisted by several auxiliary factors. We demonstrate that an essential initiation factor, TFB2, forms a network of interactions with DNA near the transcription start site and facilitates promoter melting but may not be essential for promoter recognition. Unexpectedly, catalytic autolabeling reveals that TFB2 interacts with the priming substrate, suggesting that TFB2 acts as a transient component of...

  3. Cyclic AMP and AKAP-mediated targeting of protein kinase A regulates lactate dehydrogenase subunit A mRNA stability.

    Science.gov (United States)

    Jungmann, Richard A; Kiryukhina, Olga

    2005-07-01

    Expression of the lactate dehydrogenase A subunit (ldh-A) gene is controlled through transcriptional as well as post-transcriptional mechanisms. Both mechanisms involve activation of protein kinase A (PKA) into its subunits and subsequent phosphorylation and activation of several key regulatory factors. In rat C6 glioma cells, post-transcriptional gene regulation occurs through PKA-mediated stabilization of LDH-A mRNA and subsequent increase of intracellular LDH-A mRNA levels. Previous studies have demonstrated a cAMP-stabilizing region (CSR) located in the LDH-A 3'-untranslated region which, in combination with several phosphorylated CSR-binding proteins (CSR-BP), regulates the PKA-mediated stabilization of LDH-A mRNA. However, the mechanistic details of interaction of CSR with proteins as they pertain to mRNA stabilization by PKA are so far largely unknown. In this study we tested the hypothesis that ribosomal protein extracts (RSW) from glioma cells contain PKA regulatory (RII) and catalytic (C) subunits that, in combination with a protein kinase A anchoring protein (AKAP 95) and CSR-BPs participate in forming CSR-protein complexes that are responsible for mRNA stability regulation. To demonstrate the importance of CSR-protein complex formation, the PKA subunits and AKAP 95 were removed from the RSW by immunoprecipitation, and the antigen-deleted RSW were subjected to CSR binding analysis using gel mobility shift and UV cross-linking. It was shown that AKAP 95 as well as RII formed a direct linkage with CSR during CSR-protein complex formation. In contrast, the catalytic subunit formed part of the CSR-protein complex but did not bind to CSR directly in a covalent linkage. To determine whether formation of CSR complexes that included C, RII, and AKAP 95 constituted a functional event and was necessary for mRNA stabilization, cell-free decay reactions were carried out with RSW extracts, and the kinetics of decay of LDH-A mRNA was determined. Depletion of PKA

  4. Unsteady catalytic processes and sorption-catalytic technologies

    International Nuclear Information System (INIS)

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  5. Unsteady catalytic processes and sorption-catalytic technologies

    Energy Technology Data Exchange (ETDEWEB)

    Zagoruiko, A N [G.K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-07-31

    Catalytic processes that occur under conditions of the targeted unsteady state of the catalyst are considered. The highest efficiency of catalytic processes was found to be ensured by a controlled combination of thermal non-stationarity and unsteady composition of the catalyst surface. The processes based on this principle are analysed, in particular, catalytic selective reduction of nitrogen oxides, deep oxidation of volatile organic impurities, production of sulfur by the Claus process and by hydrogen sulfide decomposition, oxidation of sulfur dioxide, methane steam reforming and anaerobic combustion, selective oxidation of hydrocarbons, etc.

  6. Subunit b-dimer of the Escherichia coli ATP synthase can form left-handed coiled-coils.

    Science.gov (United States)

    Wise, John G; Vogel, Pia D

    2008-06-01

    One remaining challenge to our understanding of the ATP synthase concerns the dimeric coiled-coil stator subunit b of bacterial synthases. The subunit b-dimer has been implicated in important protein interactions that appear necessary for energy conservation and that may be instrumental in energy conservation during rotary catalysis by the synthase. Understanding the stator structure and its interactions with the rest of the enzyme is crucial to the understanding of the overall catalytic mechanism. Controversy exists on whether subunit b adopts a classic left-handed or a presumed right-handed dimeric coiled-coil and whether or not staggered pairing between nonhomologous residues in the homodimer is required for intersubunit packing. In this study we generated molecular models of the Escherichia coli subunit b-dimer that were based on the well-established heptad-repeat packing exhibited by left-handed, dimeric coiled-coils by employing simulated annealing protocols with structural restraints collected from known structures. In addition, we attempted to create hypothetical right-handed coiled-coil models and left- and right-handed models with staggered packing in the coiled-coil domains. Our analyses suggest that the available structural and biochemical evidence for subunit b can be accommodated by classic left-handed, dimeric coiled-coil quaternary structures.

  7. A infecção tuberculosa e o tempo de prisão da população carcerária dos Distritos Policiais da zona oeste da cidade de São Paulo Tuberculosis infection and the length of stay of County Jails prisoners in the western sector of the city of São Paulo

    Directory of Open Access Journals (Sweden)

    Péricles Alves Nogueira

    2009-03-01

    Full Text Available INTRODUÇÃO: A tuberculose sempre foi um grave problema de saúde para grupos de pessoas confinadas, especialmente em presídios, devido à sua transmissão respiratória. OBJETIVO: Verificar a associação entre o tempo de prisão e a taxa de infecção tuberculosa na população carcerária dos Distritos Policiais da zona oeste da cidade de São Paulo. METODOLOGIA:Foi realizado um estudo observacional, no período de março de 2000 a maio de 2001, com a aplicação de um inquérito individual e da prova tuberculínica (PPD-RT23 - 2UT/0.1ml nos detentos. RESULTADOS E DISCUSSÃO: Do total de 1.052 presos entrevistados, 932 concordaram em fazer a prova tuberculínica e, destes, 64,5% estavam infectados. Para as análises, os detentos foram classificados como primários e reincidentes e como não reatores e reatores à prova tuberculínica, segundo o tempo de prisão. Entre os 134 detentos primários que estavam presos há menos de 60 dias, 40,3% foram reatores ao PPD e dos 53 com mais de 366 dias de prisão a percentagem de reatores foi de 62,3%. Entre os 146 detentos reincidentes presos há menos de 60 dias, 72,6% foram reatores ao PPD e dos 25 com mais de 366 dias de prisão, 100,0% estava infectado. Em todos os períodos de permanência na prisão, os detentos reincidentes tiveram maior percentagem de infecção tuberculosa do que os detentos primários. A associação entre tempo de prisão e reatividade ao PPD foi confirmada pelo Teste de Tendência (pINTRODUCTION: Tuberculosis has always been a serious health problem for groups of confined individuals, especially in prisons, due to its respiratory transmission. OBJECTIVE: To verify the association between the length of stay in prison and the rate of tuberculosis infection in County Jail prisoners in the western sector of the city of São Paulo. METHODS:An observational study was conducted in 2000 and 2001 by interviewing prisoners and by conducting Tuberculin Skin Test (TST. RESULTS AND

  8. Effect of protein S-nitrosylation on autolysis and catalytic ability of μ-calpain.

    Science.gov (United States)

    Liu, Rui; Li, Yupin; Wang, Mengqin; Zhou, Guanghong; Zhang, Wangang

    2016-12-15

    The effect of S-nitrosylation on the autolysis and catalytic ability of μ-calpain in vitro in the presence of 50μM Ca(2 +) was investigated. μ-Calpain was incubated with different concentrations of nitric oxide donor S-nitrosoglutathione (GSNO) and subsequently reacted with purified myofibrils. Results showed that the amount of 80kDa μ-calpain subunit significantly decreased as GSNO increased from 0 to 300μM, but increases of GSNO to 300, 500 and 1000μM did not result in further inhibition. The catalytic ability of nitrosylated μ-calpain to degrade titin, nebulin, troponin-T and desmin was significantly reduced when the GSNO concentration was higher than 300μM. The cysteine residues of μ-calpain at positions 49, 351, 384, and 592 in the catalytic subunit and at 142 in small subunit were S-nitrosylated, which could be responsible for decreased μ-calpain activity. Thus, S-nitrosylation can negatively regulate the activation of μ-calpain resulting in decreased proteolytic ability on myofibrils. PMID:27451206

  9. Structure of the Cmr2 Subunit of the CRISPR-Cas RNA Silencing Complex

    Energy Technology Data Exchange (ETDEWEB)

    Cocozaki, Alexis I.; Ramia, Nancy F.; Shao, Yaming; Hale, Caryn R.; Terns, Rebecca M.; Terns, Michael P.; Li, Hong (FSU); (Georgia)

    2012-08-10

    Cmr2 is the largest and an essential subunit of a CRISPR RNA-Cas protein complex (the Cmr complex) that cleaves foreign RNA to protect prokaryotes from invading genetic elements. Cmr2 is thought to be the catalytic subunit of the effector complex because of its N-terminal HD nuclease domain. Here, however, we report that the HD domain of Cmr2 is not required for cleavage by the complex in vitro. The 2.3 {angstrom} crystal structure of Pyrococcus furiosus Cmr2 (lacking the HD domain) reveals two adenylyl cyclase-like and two {alpha}-helical domains. The adenylyl cyclase-like domains are arranged as in homodimeric adenylyl cyclases and bind ADP and divalent metals. However, mutagenesis studies show that the metal- and ADP-coordinating residues of Cmr2 are also not critical for cleavage by the complex. Our findings suggest that another component provides the catalytic function and that the essential role by Cmr2 does not require the identified ADP- or metal-binding or HD domains in vitro.

  10. Immunochemical aspects of crotoxim and its subunits

    International Nuclear Information System (INIS)

    Crotamine and crotoxin with the subunits - phospholipase A and crotapotin - were obtained by purification from Crotalus durissus terrificus venom. Interaction studies of the subunits using crotalic antiserum, indicated that: crotoxin is formed of crotapotin and phospholipase A with the molar ratio of 1 to 1; using crotapotin 125I the presence of a soluble complex was shown with the same antiserum. Immunological precipitation reactions demonstrated that crotapotin is antigenic: crotapotin and phospholipase A presented similar antigenic determinants; crotoxin antiserum reacted with each one of the submits; when the subunits are mixed to form synthetic crotoxin some antigenic determinants are masked in the process of interaction. Crotamine, interacted with crotapotin 1:1, without hidden antigenic determinants crotapotin antigenic site seems to be formed by, at least, one lysine. Enzimatical activity of phospholipase A apreared to be dependent on some reaction conditions when its arginine residues are blocked. Tyrosines of phospholipase A are more susceptible to labelling with 131I than crotapotin. Gama irradiation of aqueous solutions of the subunits produced modifications in the ultraviolet spectra. A decrease of the enzymatic activity occured as a function of radiation dosis. Immunological activities of crotapotin and phospholipase A were not altered

  11. Thermostable Subunit Vaccines for Pulmonary Delivery

    DEFF Research Database (Denmark)

    Foged, Camilla

    2016-01-01

    , such as influenza, tuberculosis, and Ebola, for which no good universal vaccines exist. At least two pharmaceutical improvements are expected to help filling this gap: i) The development of thermostable vaccine dosage forms, and ii) the full exploitation of the adjuvant technology for subunit vaccines to potentiate...

  12. Catalytic production of biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Theilgaard Madsen, A.

    2011-07-01

    The focus of this thesis is the catalytic production of diesel from biomass, especially emphasising catalytic conversion of waste vegetable oils and fats. In chapter 1 an introduction to biofuels and a review on different catalytic methods for diesel production from biomass is given. Two of these methods have been used industrially for a number of years already, namely the transesterification (and esterification) of oils and fats with methanol to form fatty acid methyl esters (FAME), and the hydrodeoxygenation (HDO) of fats and oils to form straight-chain alkanes. Other possible routes to diesel include upgrading and deoxygenation of pyrolysis oils or aqueous sludge wastes, condensations and reductions of sugars in aqueous phase (aqueous-phase reforming, APR) for monofunctional hydrocarbons, and gasification of any type of biomass followed by Fischer-Tropsch-synthesis for alkane biofuels. These methods have not yet been industrialised, but may be more promising due to the larger abundance of their potential feedstocks, especially waste feedstocks. Chapter 2 deals with formation of FAME from waste fats and oils. A range of acidic catalysts were tested in a model fat mixture of methanol, lauric acid and trioctanoin. Sulphonic acid-functionalised ionic liquids showed extremely fast convertion of lauric acid to methyl laurate, and trioctanoate was converted to methyl octanoate within 24 h. A catalyst based on a sulphonated carbon-matrix made by pyrolysing (or carbonising) carbohydrates, so-called sulphonated pyrolysed sucrose (SPS), was optimised further. No systematic dependency on pyrolysis and sulphonation conditions could be obtained, however, with respect to esterification activity, but high activity was obtained in the model fat mixture. SPS impregnated on opel-cell Al{sub 2}O{sub 3} and microporous SiO{sub 2} (ISPS) was much less active in the esterification than the original SPS powder due to low loading and thereby low number of strongly acidic sites on the

  13. The intein of the Thermoplasma A-ATPase A subunit: Structure, evolution and expression in E. coli

    Directory of Open Access Journals (Sweden)

    Gogarten J Peter

    2001-11-01

    Full Text Available Abstract Background Inteins are selfish genetic elements that excise themselves from the host protein during post translational processing, and religate the host protein with a peptide bond. In addition to this splicing activity, most reported inteins also contain an endonuclease domain that is important in intein propagation. Results The gene encoding the Thermoplasma acidophilum A-ATPase catalytic subunit A is the only one in the entire T. acidophilum genome that has been identified to contain an intein. This intein is inserted in the same position as the inteins found in the ATPase A-subunits encoding gene in Pyrococcus abyssi, P. furiosus and P. horikoshii and is found 20 amino acids upstream of the intein in the homologous vma-1 gene in Saccharomyces cerevisiae. In contrast to the other inteins in catalytic ATPase subunits, the T. acidophilum intein does not contain an endonuclease domain. T. acidophilum has different codon usage frequencies as compared to Escherichia coli. Initially, the low abundance of rare tRNAs prevented expression of the T. acidophilum A-ATPase A subunit in E. coli. Using a strain of E. coli that expresses additional tRNAs for rare codons, the T. acidophilum A-ATPase A subunit was successfully expressed in E. coli. Conclusions Despite differences in pH and temperature between the E. coli and the T. acidophilum cytoplasms, the T. acidophilum intein retains efficient self-splicing activity when expressed in E. coli. The small intein in the Thermoplasma A-ATPase is closely related to the endonuclease containing intein in the Pyrococcus A-ATPase. Phylogenetic analyses suggest that this intein was horizontally transferred between Pyrococcus and Thermoplasma, and that the small intein has persisted in Thermoplasma apparently without homing.

  14. Catalytic cracking of lignites

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, M.; Nowak, S.; Naegler, T.; Zimmermann, J. [Hochschule Merseburg (Germany); Welscher, J.; Schwieger, W. [Erlangen-Nuernberg Univ. (Germany); Hahn, T. [Halle-Wittenberg Univ., Halle (Germany)

    2013-11-01

    A most important factor for the chemical industry is the availability of cheap raw materials. As the oil price of crude oil is rising alternative feedstocks like coal are coming into focus. This work, the catalytic cracking of lignite is part of the alliance ibi (innovative Braunkohlenintegration) to use lignite as a raw material to produce chemicals. With this new one step process without an input of external hydrogen, mostly propylene, butenes and aromatics and char are formed. The product yield depends on manifold process parameters. The use of acid catalysts (zeolites like MFI) shows the highest amount of the desired products. Hydrogen rich lignites with a molar H/C ratio of > 1 are to be favoured. Due to primary cracking and secondary reactions the ratio between catalyst and lignite, temperature and residence time are the most important parameter to control the product distribution. Experiments at 500 C in a discontinuous rotary kiln reactor show yields up to 32 wt-% of hydrocarbons per lignite (maf - moisture and ash free) and 43 wt-% char, which can be gasified. Particularly, the yields of propylene and butenes as main products can be enhanced four times to about 8 wt-% by the use of catalysts while the tar yield decreases. In order to develop this innovative process catalyst systems fixed on beads were developed for an easy separation and regeneration of the used catalyst from the formed char. (orig.)

  15. Catalytic Membrane Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, T.J.; Brinker, C.J.; Gardner, T.J.; Hughes, R.C.; Sault, A.G.

    1998-12-01

    The proposed "catalytic membrane sensor" (CMS) was developed to generate a device which would selectively identify a specific reagent in a complex mixture of gases. This was to be accomplished by modifying an existing Hz sensor with a series of thin films. Through selectively sieving the desired component from a complex mixture and identifying it by decomposing it into Hz (and other by-products), a Hz sensor could then be used to detect the presence of the select component. The proposed "sandwich-type" modifications involved the deposition of a catalyst layered between two size selective sol-gel layers on a Pd/Ni resistive Hz sensor. The role of the catalyst was to convert organic materials to Hz and organic by-products. The role of the membraneo was to impart both chemical specificity by molecukir sieving of the analyte and converted product streams, as well as controlling access to the underlying Pd/Ni sensor. Ultimately, an array of these CMS elements encompassing different catalysts and membranes were to be developed which would enable improved selectivity and specificity from a compiex mixture of organic gases via pattern recognition methodologies. We have successfully generated a CMS device by a series of spin-coat deposited methods; however, it was determined that the high temperature required to activate the catalyst, destroys the sensor.

  16. Catalytic gasification of biomass

    Science.gov (United States)

    Robertus, R. J.; Mudge, L. K.; Sealock, L. J., Jr.; Mitchell, D. H.; Weber, S. L.

    1981-12-01

    Methane and methanol synthesis gas can be produced by steam gasification of biomass in the presence of appropriate catalysts. This concept is to use catalysts in a fluidized bed reactor which is heated indirectly. The objective is to determine the technical and economic feasibility of the concept. Technically the concept has been demonstrated on a 50 lb per hr scale. Potential advantages over conventional processes include: no oxygen plant is needed, little tar is produced so gas and water treatment are simplified, and yields and efficiencies are greater than obtained by conventional gasification. Economic studies for a plant processing 2000 T/per day dry wood show that the cost of methanol from wood by catalytic gasification is competitive with the current price of methanol. Similar studies show the cost of methane from wood is competitive with projected future costs of synthetic natural gas. When the plant capacity is decreased to 200 T per day dry wood, neither product is very attractive in today's market.

  17. Probing subunit-subunit interactions in the yeast vacuolar ATPase by peptide arrays.

    Directory of Open Access Journals (Sweden)

    Lee S Parsons

    Full Text Available BACKGROUND: Vacuolar (H(+-ATPase (V-ATPase; V(1V(o-ATPase is a large multisubunit enzyme complex found in the endomembrane system of all eukaryotic cells where its proton pumping action serves to acidify subcellular organelles. In the plasma membrane of certain specialized tissues, V-ATPase functions to pump protons from the cytoplasm into the extracellular space. The activity of the V-ATPase is regulated by a reversible dissociation mechanism that involves breaking and re-forming of protein-protein interactions in the V(1-ATPase - V(o-proton channel interface. The mechanism responsible for regulated V-ATPase dissociation is poorly understood, largely due to a lack of detailed knowledge of the molecular interactions that are responsible for the structural and functional link between the soluble ATPase and membrane bound proton channel domains. METHODOLOGY/PRINCIPAL FINDINGS: To gain insight into where some of the stator subunits of the V-ATPase associate with each other, we have developed peptide arrays from the primary sequences of V-ATPase subunits. By probing the peptide arrays with individually expressed V-ATPase subunits, we have identified several key interactions involving stator subunits E, G, C, H and the N-terminal domain of the membrane bound a subunit. CONCLUSIONS: The subunit-peptide interactions identified from the peptide arrays complement low resolution structural models of the eukaryotic vacuolar ATPase obtained from transmission electron microscopy. The subunit-subunit interaction data are discussed in context of our current model of reversible enzyme dissociation.

  18. Structural and evolutionary relationships among RuBisCOs inferred from their large and small subunits.

    Science.gov (United States)

    Xiang, Fu; Fang, Yuanping; Xiang, Jun

    2016-01-01

    Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key enzyme to assimilate CO(2) into the biosphere. The nonredundant structural data sets for three RuBisCO domain superfamilies, i.e. large subunit C-terminal domain (LSC), large subunit N-terminal domain (LSN) and small subunit domain (SS), were selected using QR factorization based on the structural alignment with QH as the similarity measure. The structural phylogenies were then constructed to investigate a possible functional significance of the evolutionary diversification. The LSC could have occurred in both bacteria and archaea, and has evolved towards increased complexity in both bacteria and eukaryotes with a 4-helix-2-helix-2-helix bundle being extended into a 5-helix-3-helix-3-helix one at the LSC carboxyl-terminus. The structural variations of LSN could have originated not only in bacteria with a short coil, but also in eukaryotes with a long one. Meanwhile, the SS dendrogram can be contributed to the structural variations at the βA-βB-loop region. All the structural variations observed in the coil regions have influence on catalytic performance or CO(2)/O(2) selectivities of RuBisCOs from different species. Such findings provide insights on RuBisCO improvements. PMID:27049618

  19. The Pseudorabies Virus DNA Polymerase Accessory Subunit UL42 Directs Nuclear Transport of the Holoenzyme.

    Science.gov (United States)

    Wang, Yi-Ping; Du, Wen-Juan; Huang, Li-Ping; Wei, Yan-Wu; Wu, Hong-Li; Feng, Li; Liu, Chang-Ming

    2016-01-01

    Pseudorabies virus (PRV) DNA replication occurs in the nuclei of infected cells and requires the viral DNA polymerase. The PRV DNA polymerase comprises a catalytic subunit, UL30, and an accessory subunit, UL42, that confers processivity to the enzyme. Its nuclear localization is a prerequisite for its enzymatic function in the initiation of viral DNA replication. However, the mechanisms by which the PRV DNA polymerase holoenzyme enters the nucleus have not been determined. In this study, we characterized the nuclear import pathways of the PRV DNA polymerase catalytic and accessory subunits. Immunofluorescence analysis showed that UL42 localizes independently in the nucleus, whereas UL30 alone predominantly localizes in the cytoplasm. Intriguingly, the localization of UL30 was completely shifted to the nucleus when it was coexpressed with UL42, demonstrating that nuclear transport of UL30 occurs in an UL42-dependent manner. Deletion analysis and site-directed mutagenesis of the two proteins showed that UL42 contains a functional and transferable bipartite nuclear localization signal (NLS) at amino acids 354-370 and that K(354), R(355), and K(367) are important for the NLS function, whereas UL30 has no NLS. Coimmunoprecipitation assays verified that UL42 interacts with importins α3 and α4 through its NLS. In vitro nuclear import assays demonstrated that nuclear accumulation of UL42 is a temperature- and energy-dependent process and requires both importins α and β, confirming that UL42 utilizes the importin α/β-mediated pathway for nuclear entry. In an UL42 NLS-null mutant, the UL42/UL30 heterodimer was completely confined to the cytoplasm when UL42 was coexpressed with UL30, indicating that UL30 utilizes the NLS function of UL42 for its translocation into the nucleus. Collectively, these findings suggest that UL42 contains an importin α/β-mediated bipartite NLS that transports the viral DNA polymerase holoenzyme into the nucleus in an in vitro expression

  20. The autophosphorylation and p34cdc2 phosphorylation sites of casein kinase-2 beta-subunit are not essential for reconstituting the fully-active heterotetrameric holoenzyme

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Issinger, O G;

    1993-01-01

    Two mutants of human casein kinase-2 beta-subunit with short deletions at either their amino (delta 1-4) or carboxy (delta 209-215) terminal side have been created that have lost the capability to undergo autophosphorylation and p34cdc2 mediated phosphorylation, respectively. Both mutants give rise...... to reconstituted CK2 holoenzymes displaying basal catalytic activity, thermostability and responsiveness to polylysine, identical to those of wild-type holoenzyme, whose reconstitution, moreover, is not affected by previous phosphorylation of the beta-subunit at either its N-terminal or C-terminal sites. Unlike...

  1. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brownian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d=3.

  2. Immigration process in catalytic medium

    Institute of Scientific and Technical Information of China (English)

    洪文明; 王梓坤

    2000-01-01

    The longtime behavior of the immigration process associated with a catalytic super-Brown-ian motion is studied. A large number law is proved in dimension d≤3 and a central limit theorem is proved for dimension d = 3.

  3. Domain III function of Mu transposase analysed by directed placement of subunits within the transpososome

    Indian Academy of Sciences (India)

    Susana Mariconda; Soon-Young Namgoong; Ki-Hoon Yoon; Hong Jiang; Rasika M Harshey

    2000-12-01

    Assembly of the functional tetrameric form of Mu transposase (MuA protein) at the two att ends of Mu depends on interaction of MuA with multiple att and enhancer sites on supercoiled DNA, and is stimulated by MuB protein. The N-terminal domain I of MuA harbours distinct regions for interaction with the att ends and enhancer; the C-terminal domain III contains separate regions essential for tetramer assembly and interaction with MuB protein (III and III, respectively). Although the central domain II (the ‘DDE’ domain) of MuA harbours the known catalytic DDE residues, a 26 amino acid peptide within III also has a non-specific DNA binding and nuclease activity which has been implicated in catalysis. One model proposes that active sites for Mu transposition are assembled by sharing structural/catalytic residues between domains II and III present on separate MuA monomers within the MuA tetramer. We have used substrates with altered att sites and mixtures of MuA proteins with either wild-type or altered att DNA binding specificities, to create tetrameric arrangements wherein specific MuA subunits are nonfunctional in II, III or III domains. From the ability of these oriented tetramers to carry out DNA cleavage and strand transfer we conclude that domain III or III function is not unique to a specific subunit within the tetramer, indicative of a structural rather than a catalytic function for domain III in Mu transposition.

  4. Dynamic regulation of β1 subunit trafficking controls vascular contractility

    OpenAIRE

    Leo, M. Dennis; Bannister, John P.; Narayanan, Damodaran; Nair, Anitha; Grubbs, Jordan E.; Gabrick, Kyle S.; Boop, Frederick A.; Jaggar, Jonathan H.

    2014-01-01

    Plasma membrane ion channels composed of pore-forming and auxiliary subunits regulate physiological functions in virtually all cell types. A conventional view is that ion channels assemble with their auxiliary subunits prior to surface trafficking of the multiprotein complex. Arterial myocytes express large-conductance Ca2+-activated potassium (BK) channel α and auxiliary β1 subunits that modulate contractility and blood pressure and flow. The data here show that although most BKα subunits ar...

  5. Structural Comparison, Substrate Specificity, and Inhibitor Binding of AGPase Small Subunit from Monocot and Dicot: Present Insight and Future Potential

    Directory of Open Access Journals (Sweden)

    Kishore Sarma

    2014-01-01

    Full Text Available ADP-glucose pyrophosphorylase (AGPase is the first rate limiting enzyme of starch biosynthesis pathway and has been exploited as the target for greater starch yield in several plants. The structure-function analysis and substrate binding specificity of AGPase have provided enormous potential for understanding the role of specific amino acid or motifs responsible for allosteric regulation and catalytic mechanisms, which facilitate the engineering of AGPases. We report the three-dimensional structure, substrate, and inhibitor binding specificity of AGPase small subunit from different monocot and dicot crop plants. Both monocot and dicot subunits were found to exploit similar interactions with the substrate and inhibitor molecule as in the case of their closest homologue potato tuber AGPase small subunit. Comparative sequence and structural analysis followed by molecular docking and electrostatic surface potential analysis reveal that rearrangements of secondary structure elements, substrate, and inhibitor binding residues are strongly conserved and follow common folding pattern and orientation within monocot and dicot displaying a similar mode of allosteric regulation and catalytic mechanism. The results from this study along with site-directed mutagenesis complemented by molecular dynamics simulation will shed more light on increasing the starch content of crop plants to ensure the food security worldwide.

  6. MspA Nanopores from Subunit Dimers

    OpenAIRE

    Pavlenok, Mikhail; Derrington, Ian M.; Gundlach, Jens H.; Niederweis, Michael

    2012-01-01

    Mycobacterium smegmatis porin A (MspA) forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated tha...

  7. Expression of Telomerase Subunits in Gastric Cancer

    Institute of Scientific and Technical Information of China (English)

    CHEN Fenghua; HU Lihua; LI Yirong; WANG Lin

    2005-01-01

    To detect the expression of telomerase subunits human telomerase reverse transcriptase, human telomerase associated protein 1 and human telomerase RNA) in gastric cancer and to examine the role that different telomerase subunits play in the gastric carcinogenesis, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect telomerase subunits messenger RNA in 24 samples of gastric cancer and corresponding non-cancerous tissue. The results showed that the positive rate of hTERT mRNA from gastric cancer and corresponding non-cancerous tissues was 100 % and 25 %, respectively. The former was significantly higher than the latter (χ2 =26.4, P<0.01). The positive rate of hTEP1 mRNA from gastric cancer and corresponding non-cancerous tissues was 100 % and 91.7 %, respectively and no significant difference was found between them (χ2 =2.1, P>0.05). The positive rates of hTR for gastric cancer and corresponding non-cancerous tissues were both 100 % and no significant difference existed between them. It is concluded that in contrast to hTEP1 and hTR, the up-regulation of hTERT mRNA expression may play a more important role in the development of gastric cancer.

  8. Subunit organization in cytoplasmic dynein subcomplexes

    Science.gov (United States)

    King, Stephen J.; Bonilla, Myriam; Rodgers, Michael E.; Schroer, Trina A.

    2002-01-01

    Because cytoplasmic dynein plays numerous critical roles in eukaryotic cells, determining the subunit composition and the organization and functions of the subunits within dynein are important goals. This has been difficult partly because of accessory polypeptide heterogeneity of dynein populations. The motor domain containing heavy chains of cytoplasmic dynein are associated with multiple intermediate, light intermediate, and light chain accessory polypeptides. We examined the organization of these subunits within cytoplasmic dynein by separating the molecule into two distinct subcomplexes. These subcomplexes were competent to reassemble into a molecule with dynein-like properties. One subcomplex was composed of the dynein heavy and light intermediate chains whereas the other subcomplex was composed of the intermediate and light chains. The intermediate and light chain subcomplex could be further separated into two pools, only one of which contained dynein light chains. The two pools had distinct intermediate chain compositions, suggesting that intermediate chain isoforms have different light chain–binding properties. When the two intermediate chain pools were characterized by analytical velocity sedimentation, at least four molecular components were seen: intermediate chain monomers, intermediate chain dimers, intermediate chain monomers with bound light chains, and a mixture of intermediate chain dimers with assorted bound light chains. These data provide new insights into the compositional heterogeneity and assembly of the cytoplasmic dynein complex and suggest that individual dynein molecules have distinct molecular compositions in vivo. PMID:11967380

  9. Na+ channel β subunits: Overachievers of the ion channel family

    OpenAIRE

    LoriLIsom; WilliamJBrackenbury

    2011-01-01

    Voltage gated Na+ channels (VGSCs) in mammals contain a pore-forming α subunit and one or more β subunits. There are five mammalian β subunits in total: β1, β1B, β2, β3, and β4, encoded by four genes: SCN1B-SCN4B. With the exception of the SCN1B splice variant, β1B, the β subunits are type I topology transmembrane proteins. In contrast, β1B lacks a transmembrane domain and is a secreted protein. A growing body of work shows that VGSC β subunits are multifunctional. While they do not form the...

  10. P. berghei telomerase subunit TERT is essential for parasite survival.

    Directory of Open Access Journals (Sweden)

    Agnieszka A Religa

    Full Text Available Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA, though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT, is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF analysis. TERT and TR were detected in blood stages and an average telomere length of ∼ 950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert- mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further

  11. Cloning, Characterization, and Distribution of an mRNA Encoding a H+-ATPase α Subunit in the Mantle of Pearl Oyster, Pinctada fucata

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Mitochondrial ATP synthase is responsible for the production of the majority of the cellular ATP,which is composed of two major units: F0 and F1. Although much is known about the active complex (5 subunits (αβγδε)), the role of the α subunit in the catalytic mechanism remains unclear, particularly in bivalve animals. This study first cloned and identified the full-length sequence of the mitochondrial H+-ATP synthase α subunit cDNA gene in Pinctada fucata using the reverse transcriptase polymerase chain reaction (RT-PCR)technique. The Pinctada fucata mitochondrial H+-ATP synthase α subunit contains 1991 nucleotides, with the translation start site at nt 48 (ATG) and the stop codon at nt 1660 (TAA), encoding a polypeptide 553 amino acids in length, which shares high similarity to that of other animals (81% identity to fruit fly, 82% to carp, and 83% to humans). Alignment analysis of the well-conserved amino acid domains in the ATPase α subunit, the α/β signal transduction domain, showed that two residues (Asp358 and Asn359) differ from any other ATP synthase α subunit. In situ hybridization analysis was used to reveal the wide-spread distribution of mitochondrial H+-ATP synthase in various tissues in Pinctada fucata. This work will help further research on pearl energy metabolism to increase the output and quality of pearls to more efficiently utilize our rich pearl oyster resources.

  12. Comprehensive Characterization of AMP-Activated Protein Kinase Catalytic Domain by Top-Down Mass Spectrometry

    Science.gov (United States)

    Yu, Deyang; Peng, Ying; Ayaz-Guner, Serife; Gregorich, Zachery R.; Ge, Ying

    2016-02-01

    AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase that is essential in regulating energy metabolism in all eukaryotic cells. It is a heterotrimeric protein complex composed of a catalytic subunit (α) and two regulatory subunits (β and γ). C-terminal truncation of AMPKα at residue 312 yielded a protein that is active upon phosphorylation of Thr172 in the absence of β and γ subunits, which is refered to as the AMPK catalytic domain and commonly used to substitute for the AMPK heterotrimeric complex in in vitro kinase assays. However, a comprehensive characterization of the AMPK catalytic domain is lacking. Herein, we expressed a His-tagged human AMPK catalytic domin (denoted as AMPKΔ) in E. coli, comprehensively characterized AMPKΔ in its basal state and after in vitro phosphorylation using top-down mass spectrometry (MS), and assessed how phosphorylation of AMPKΔ affects its activity. Unexpectedly, we found that bacterially-expressed AMPKΔ was basally phosphorylated and localized the phosphorylation site to the His-tag. We found that AMPKΔ had noticeable basal activity and was capable of phosphorylating itself and its substrates without activating phosphorylation at Thr172. Moreover, our data suggested that Thr172 is the only site phosphorylated by its upstream kinase, liver kinase B1, and that this phosphorylation dramatically increases the kinase activity of AMPKΔ. Importantly, we demonstrated that top-down MS in conjunction with in vitro phosphorylation assay is a powerful approach for monitoring phosphorylation reaction and determining sequential order of phosphorylation events in kinase-substrate systems.

  13. Molecular cloning and differential expression patterns of the regulatory subunit B’ gene of PP2A in goldfish,Carassius auratus

    Institute of Scientific and Technical Information of China (English)

    LI; David; WanCheng

    2009-01-01

    It is well established that the protein serine/threonine phosphatase 2A(PP2A) plays very important roles in many different cellular processes,including cell proliferation and differentiation,gene expression,neurotransmission,apoptosis,and aging.PP2A consists of three heterogenic subunits:the scaffold subunit A,the catalytic subunit C,and the regulatory subunit B.While both the scaffold and the catalytic subunits contain only two forms,at least four families of the regulatory subunits,B,B’,B’’,and B’’’ have been identified.These regulatory subunits from different families are encoded by different genes and bear other functions besides directing the specificity of PP2A.To study the functions of the regulatory subunits of PP2A in lower vertebrates,we have cloned the full-length cDNA sequence of the gene encoding the regulatory subunit B’δ of PP2A from gold fish,Carassius auratus using 3’-RACE and 5’-RACE cloning strategies.Our results revealed that the full-length B’δ cDNA contains 2415 bp and encodes a protein of 555 amino acids.The B’δ protein displays a very high level of sequence identity with the B’δ regulatory subunit from other species of vertebrates.Regarding its expression pattern,RT-PCR revealed that the highest level of mRNA was detected in brain,a less level detected in liver,spermary,ovary,kidney and gill,and the lowest level detected in the fin.During different developmental stages of gold fish,the highest level of mRNA expression was detected at the stages of two-cell,multiple-cell,blastula and gastrula,and a decreased level of B’δ mRNA was detected in other developmental stages.At the protein level,the highest expression level of B’δ protein was found in spermary,ovary,brain and heart,a less amount found in liver and the lowest level detected in kidney,gill and fin.Developmentally,B’δ protein was strongly expressed at the stages of two-cell,multiple-cell,blastula,gastrula,neurula,and optic vesicle,and then decreased

  14. Cobalamin Catalytic Centers for Stable Fuels Generation from Carbon Dioxide

    Science.gov (United States)

    Robertson, Wesley D.; Jawdat, Benmaan I.; Ennist, Nathan M.; Warncke, Kurt

    2010-03-01

    Our aim is to design and construct protein-based artificial photosynthetic systems that reduce carbon dioxide (CO2) to stable fuel forms within the robust and adaptable (βα)8 TIM-barrel protein structure. The EutB subunit of the adenosylcobalamin-dependent enzyme, ethanolamine ammonia-lyase, from Salmonella typhimurium, was selected as the protein template. This system was selected because the Co^I forms of the native cobalamin (Cbl) cofactor, and the related cobinamide (Cbi), possess redox properties that are commensurate with reduction of CO2. The kinetics of photo- (excited 5'-deazariboflavin electron donor) and chemical [Ti(III)] reduction, and subsequent reaction, of the Cbl and Cbi with CO2 are measured by time-resolved UV/visible absorption spectroscopy. Products are quantified by NMR spectroscopy. The results address the efficacy of the organocobalt catalytic centers for CO2 reduction to stable fuels, towards protein device integration.

  15. Coordinated DNA dynamics during the human telomerase catalytic cycle

    Science.gov (United States)

    Parks, Joseph W.; Stone, Michael D.

    2014-06-01

    The human telomerase reverse transcriptase (hTERT) utilizes a template within the integral RNA subunit (hTR) to direct extension of telomeres. Telomerase exhibits repeat addition processivity (RAP) and must therefore translocate the nascent DNA product into a new RNA:DNA hybrid register to prime each round of telomere repeat synthesis. Here, we use single-molecule FRET and nuclease protection assays to monitor telomere DNA structure and dynamics during the telomerase catalytic cycle. DNA translocation during RAP proceeds through a previously uncharacterized kinetic substep during which the 3‧-end of the DNA substrate base pairs downstream within the hTR template. The rate constant for DNA primer realignment reveals this step is not rate limiting for RAP, suggesting a second slow conformational change repositions the RNA:DNA hybrid into the telomerase active site and drives the extrusion of the 5‧-end of the DNA primer out of the enzyme complex.

  16. Fluorescent fusion proteins of soluble guanylyl cyclase indicate proximity of the heme nitric oxide domain and catalytic domain.

    Directory of Open Access Journals (Sweden)

    Tobias Haase

    Full Text Available BACKGROUND: To examine the structural organisation of heterodimeric soluble guanylyl cyclase (sGC Förster resonance energy transfer (FRET was measured between fluorescent proteins fused to the amino- and carboxy-terminal ends of the sGC beta1 and alpha subunits. METHODOLOGY/PRINCIPAL FINDINGS: Cyan fluorescent protein (CFP was used as FRET donor and yellow fluorescent protein (YFP as FRET acceptor. After generation of recombinant baculovirus, fluorescent-tagged sGC subunits were co-expressed in Sf9 cells. Fluorescent variants of sGC were analyzed in vitro in cytosolic fractions by sensitized emission FRET. Co-expression of the amino-terminally tagged alpha subunits with the carboxy-terminally tagged beta1 subunit resulted in an enzyme complex that showed a FRET efficiency of 10% similar to fluorescent proteins separated by a helix of only 48 amino acids. Because these findings indicated that the amino-terminus of the alpha subunits is close to the carboxy-terminus of the beta1 subunit we constructed fusion proteins where both subunits are connected by a fluorescent protein. The resulting constructs were not only fluorescent, they also showed preserved enzyme activity and regulation by NO. CONCLUSIONS/SIGNIFICANCE: Based on the ability of an amino-terminal fragment of the beta1 subunit to inhibit activity of an heterodimer consisting only of the catalytic domains (alphacatbetacat, Winger and Marletta (Biochemistry 2005, 44:4083-90 have proposed a direct interaction of the amino-terminal region of beta1 with the catalytic domains. In support of such a concept of "trans" regulation of sGC activity by the H-NOX domains our results indicate that the domains within sGC are organized in a way that allows for direct interaction of the amino-terminal regulatory domains with the carboxy-terminal catalytic region. In addition, we constructed "fluorescent-conjoined" sGC's by fusion of the alpha amino-terminus to the beta1 carboxy-terminus leading to a

  17. A novel mechanism of V-type zinc inhibition of glutamate dehydrogenase results from disruption of subunit interactions necessary for efficient catalysis.

    Science.gov (United States)

    Bailey, Jaclyn; Powell, Lakeila; Sinanan, Leander; Neal, Jacob; Li, Ming; Smith, Thomas; Bell, Ellis

    2011-09-01

    Bovine glutamate dehydrogenase is potently inhibited by zinc and the major impact is on V(max) suggesting a V-type effect on catalysis or product release. Zinc inhibition decreases as glutamate concentrations decrease suggesting a role for subunit interactions. With the monocarboxylic amino acid norvaline, which gives no evidence of subunit interactions, zinc does not inhibit. Zinc significantly decreases the size of the pre-steady state burst in the reaction but does not affect NADPH binding in the enzyme-NADPH-glutamate complex that governs the steady state turnover, again suggesting that zinc disrupts subunit interactions required for catalytic competence. While differential scanning calorimetry suggests zinc binds and induces a slightly conformationally more rigid state of the protein, limited proteolysis indicates that regions in the vicinity of the antennae regions and the trimer-trimer interface become more flexible. The structures of glutamate dehydrogenase bound with zinc and europium show that zinc binds between the three dimers of subunits in the hexamer, a region shown to bind novel inhibitors that block catalytic turnover, which is consistent with the above findings. In contrast, europium binds to the base of the antenna region and appears to abrogate the inhibitory effect of zinc. Structures of various states of the enzyme have shown that both regions are heavily involved in the conformational changes associated with catalytic turnover. These results suggest that the V-type inhibition produced with glutamate as the substrate results from disruption of subunit interactions necessary for efficient catalysis rather than by a direct effect on the active site conformation. PMID:21749647

  18. Catalytic distillation water recovery subsystem

    Science.gov (United States)

    Budininkas, P.; Rasouli, F.

    1985-01-01

    An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine based on the vapor phase catalytic ammonia removal was designed, fabricated and tested. Unlike other evaporative methods, this process catalytically oxidizes ammonia and volatile hydrocarbons vaporizing with water to innocuous products; therefore, no pretreatment of urine is required. Since the subsystem is fabricated from commercially available components, its volume, weight and power requirements are not optimized; however, it is suitable for zero-g operation. The testing program consists of parametric tests, one month of daily tests and a continuous test of 168 hours duration. The recovered water is clear, odorless, low in ammonia and organic carbon, and requires only an adjustment of its pH to meet potable water standards. The obtained data indicate that the vapor phase catalytic ammonia removal process, if further developed, would also be competitive with other water recovery systems in weight, volume and power requirements.

  19. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    Vivek V Ranade

    2014-03-01

    Catalytic reactions are ubiquitous in chemical and allied industries. A homogeneous or heterogeneous catalyst which provides an alternative route of reaction with lower activation energy and better control on selectivity can make substantial impact on process viability and economics. Extensive studies have been conducted to establish sound basis for design and engineering of reactors for practising such catalytic reactions and for realizing improvements in reactor performance. In this article, application of recent (and not so recent) developments in engineering reactors for catalytic reactions is discussed. Some examples where performance enhancement was realized by catalyst design, appropriate choice of reactor, better injection and dispersion strategies and recent advances in process intensification/ multifunctional reactors are discussed to illustrate the approach.

  20. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne;

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...... with particle size. We find that the fraction of low-coordinated Au atoms scales approximately with the catalytic activity, suggesting that atoms on the corners and edges of Au nanoparticles are the active sites. This effect is explained using density functional calculations....

  1. Structure-function analysis of the beta regulatory subunit of protein kinase CK2 by targeting embryonic stem cell.

    Science.gov (United States)

    Ziercher, Léa; Filhol, Odile; Laudet, Béatrice; Prudent, Renaud; Cochet, Claude; Buchou, Thierry

    2011-10-01

    Programs that govern stem cell maintenance and pluripotency are dependent on extracellular factors and of intrinsic cell modulators. Embryonic stem (ES) cells with a specific depletion of the gene encoding the regulatory subunit of protein kinase CK2 (CK2β) revealed a viability defect. However, analysis of CK2β functions along the neural lineage established CK2β as a positive regulator for neural stem/progenitor cell (NSC) proliferation and multipotency. By using an in vitro genetic conditional approach, we demonstrate in this work that specific domains of CK2β involved in the regulatory function towards CK2 catalytic subunits are crucial structural determinants for ES cell homeostasis. PMID:21861102

  2. MspA nanopores from subunit dimers.

    Directory of Open Access Journals (Sweden)

    Mikhail Pavlenok

    Full Text Available Mycobacterium smegmatis porin A (MspA forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore

  3. MspA nanopores from subunit dimers.

    Science.gov (United States)

    Pavlenok, Mikhail; Derrington, Ian M; Gundlach, Jens H; Niederweis, Michael

    2012-01-01

    Mycobacterium smegmatis porin A (MspA) forms an octameric channel and represents the founding member of a new family of pore proteins. Control of subunit stoichiometry is important to tailor MspA for nanotechnological applications. In this study, two MspA monomers were connected by linkers ranging from 17 to 62 amino acids in length. The oligomeric pore proteins were purified from M. smegmatis and were shown to form functional channels in lipid bilayer experiments. These results indicated that the peptide linkers did not prohibit correct folding and localization of MspA. However, expression levels were reduced by 10-fold compared to wild-type MspA. MspA is ideal for nanopore sequencing due to its unique pore geometry and its robustness. To assess the usefulness of MspA made from dimeric subunits for DNA sequencing, we linked two M1-MspA monomers, whose constriction zones were modified to enable DNA translocation. Lipid bilayer experiments demonstrated that this construct also formed functional channels. Voltage gating of MspA pores made from M1 monomers and M1-M1 dimers was identical indicating similar structural and dynamic channel properties. Glucose uptake in M. smegmatis cells lacking porins was restored by expressing the dimeric mspA M1 gene indicating correct folding and localization of M1-M1 pores in their native membrane. Single-stranded DNA hairpins produced identical ionic current blockades in pores made from monomers and subunit dimers demonstrating that M1-M1 pores are suitable for DNA sequencing. This study provides the proof of principle that production of single-chain MspA pores in M. smegmatis is feasible and paves the way for generating MspA pores with altered stoichiometries. Subunit dimers enable better control of the chemical and physical properties of the constriction zone of MspA. This approach will be valuable both in understanding transport across the outer membrane in mycobacteria and in tailoring MspA for nanopore sequencing of DNA. PMID

  4. Molecular evolution of Phox-related regulatory subunits for NADPH oxidase enzymes

    Directory of Open Access Journals (Sweden)

    Lambeth J David

    2007-09-01

    Full Text Available Abstract Background The reactive oxygen-generating NADPH oxidases (Noxes function in a variety of biological roles, and can be broadly classified into those that are regulated by subunit interactions and those that are regulated by calcium. The prototypical subunit-regulated Nox, Nox2, is the membrane-associated catalytic subunit of the phagocyte NADPH-oxidase. Nox2 forms a heterodimer with the integral membrane protein, p22phox, and this heterodimer binds to the regulatory subunits p47phox, p67phox, p40phox and the small GTPase Rac, triggering superoxide generation. Nox-organizer protein 1 (NOXO1 and Nox-activator 1 (NOXA1, respective homologs of p47phox and p67phox, together with p22phox and Rac, activate Nox1, a non-phagocytic homolog of Nox2. NOXO1 and p22phox also regulate Nox3, whereas Nox4 requires only p22phox. In this study, we have assembled and analyzed amino acid sequences of Nox regulatory subunit orthologs from vertebrates, a urochordate, an echinoderm, a mollusc, a cnidarian, a choanoflagellate, fungi and a slime mold amoeba to investigate the evolutionary history of these subunits. Results Ancestral p47phox, p67phox, and p22phox genes are broadly seen in the metazoa, except for the ecdysozoans. The choanoflagellate Monosiga brevicollis, the unicellular organism that is the closest relatives of multicellular animals, encodes early prototypes of p22phox, p47phox as well as the earliest known Nox2-like ancestor of the Nox1-3 subfamily. p67phox- and p47phox-like genes are seen in the sea urchin Strongylocentrotus purpuratus and the limpet Lottia gigantea that also possess Nox2-like co-orthologs of vertebrate Nox1-3. Duplication of primordial p47phox and p67phox genes occurred in vertebrates, with the duplicated branches evolving into NOXO1 and NOXA1. Analysis of characteristic domains of regulatory subunits suggests a novel view of the evolution of Nox: in fish, p40phox participated in regulating both Nox1 and Nox2, but after the

  5. Adenylate cyclase toxin-mediated delivery of the S1 subunit of pertussis toxin into mammalian cells.

    Science.gov (United States)

    Iwaki, Masaaki; Konda, Toshifumi

    2016-02-01

    The adenylate cyclase toxin (ACT) of Bordetella pertussis internalizes its catalytic domain into target cells. ACT can function as a tool for delivering foreign protein antigen moieties into immune effector cells to induce a cytotoxic T lymphocyte response. In this study, we replaced the catalytic domain of ACT with an enzymatically active protein moiety, the S1 (ADP-ribosyltransferase) subunit of pertussis toxin (PT). The S1 moiety was successfully internalized independent of endocytosis into sheep erythrocytes. The introduced polypeptide exhibited ADP-ribosyltransferase activity in CHO cells and induced clustering typical to PT. The results indicate that ACT can act as a vehicle for not only epitopes but also enzymatically active peptides to mammalian cells.

  6. Hypersecretion of the alpha-subunit in clinically non-functioning pituitary adenomas: Diagnostic accuracy is improved by adding alpha-subunit/gonadotropin ratio to levels of alpha-subunit

    DEFF Research Database (Denmark)

    Andersen, Marianne; Ganc-Petersen, Joanna; Jørgensen, Jens O L;

    2010-01-01

    In vitro, the majority of clinically non-functioning pituitary adenomas (NFPAs) produce gonadotropins or their alpha-subunit; however, in vivo, measurements of alpha-subunit levels may not accurately detect the hypersecretion of the alpha-subunit.......In vitro, the majority of clinically non-functioning pituitary adenomas (NFPAs) produce gonadotropins or their alpha-subunit; however, in vivo, measurements of alpha-subunit levels may not accurately detect the hypersecretion of the alpha-subunit....

  7. Na+/K+-ATPase α-subunit in swimming crab Portunus trituberculatus: molecular cloning, characterization, and expression under low salinity stress

    Science.gov (United States)

    Han, Xiaolin; Liu, Ping; Gao, Baoquan; Wang, Haofeng; Duan, Yafei; Xu, Wenfei; Chen, Ping

    2015-07-01

    Na+/K+-ATPases are membrane-associated enzymes responsible for the active transport of Na+ and K+ ions across cell membranes, generating chemical and electrical gradients. These enzymes' α-subunit provides catalytic function, binding and hydrolyzing ATP, and itself becoming phosphorylated during the transport cycle. In this study, Na+/K+-ATPase α-subunit cDNA was cloned from gill tissue of the swimming crab Portunus trituberculatus by reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA end methods. Analysis of the nucleotide sequence revealed that the cDNA had a full-length of 3 833 base pairs (bp), with an open reading frame of 3 120 bp, 5' untranslated region (UTR) of 317 bp, and 3' UTR of 396 bp. The sequence encoded a 1 039 amino acid protein with a predicted molecular weight of 115.57 kDa and with estimated pI of 5.21. It was predicted here to possess all expected features of Na+/K+-ATPase members, including eight transmembrane domains, putative ATP-binding site, and phosphorylation site. Comparison of amino acid sequences showed that the P. trituberculatus α-subunit possessed an overall identity of 75%-99% to that of other organisms. Phylogenetic analysis revealed that this α-subunit was in the same category as those of crustaceans. Quantitative real-time RT-PCR analysis indicated that this α-subunit's transcript were most highly expressed in gill and lowest in muscle. RT-PCR analysis also revealed that α-subunit expression in crab gill decreased after 2 and 6 h, but increased after 12, 24, 48, and 72 h. In addition, α-subunit expression in hepatopancreas of crab decreased after 2-72 h. These facts indicated that the crab's Na+/K+-ATPase α-subunit was potentially involved in the observed acute response to low salinity stress.

  8. Catalytic properties of niobium compounds

    International Nuclear Information System (INIS)

    The catalytic activity and selectivity of niobium compounds including oxides, salts, organometallic compounds and others are outlined. The application of these compounds as catalysts to diversified reactions is reported. The nature and action of niobium catalysts are characteristic and sometimes anomalous, suggesting the necessity of basic research and the potential use as catalysts for important processes in the chemical industry. (Author)

  9. Simple, chemoselective, catalytic olefin isomerization.

    Science.gov (United States)

    Crossley, Steven W M; Barabé, Francis; Shenvi, Ryan A

    2014-12-01

    Catalytic amounts of Co(Sal(tBu,tBu))Cl and organosilane irreversibly isomerize terminal alkenes by one position. The same catalysts effect cycloisomerization of dienes and retrocycloisomerization of strained rings. Strong Lewis bases like amines and imidazoles, and labile functionalities like epoxides, are tolerated.

  10. The non-catalytic domains of Drosophila katanin regulate its abundance and microtubule-disassembly activity.

    Directory of Open Access Journals (Sweden)

    Kyle D Grode

    Full Text Available Microtubule severing is a biochemical reaction that generates an internal break in a microtubule and regulation of microtubule severing is critical for cellular processes such as ciliogenesis, morphogenesis, and meiosis and mitosis. Katanin is a conserved heterodimeric ATPase that severs and disassembles microtubules, but the molecular determinants for regulation of microtubule severing by katanin remain poorly defined. Here we show that the non-catalytic domains of Drosophila katanin regulate its abundance and activity in living cells. Our data indicate that the microtubule-interacting and trafficking (MIT domain and adjacent linker region of the Drosophila katanin catalytic subunit Kat60 cooperate to regulate microtubule severing in two distinct ways. First, the MIT domain and linker region of Kat60 decrease its abundance by enhancing its proteasome-dependent degradation. The Drosophila katanin regulatory subunit Kat80, which is required to stabilize Kat60 in cells, conversely reduces the proteasome-dependent degradation of Kat60. Second, the MIT domain and linker region of Kat60 augment its microtubule-disassembly activity by enhancing its association with microtubules. On the basis of our data, we propose that the non-catalytic domains of Drosophila katanin serve as the principal sites of integration of regulatory inputs, thereby controlling its ability to sever and disassemble microtubules.

  11. Comparative Analysis of Eubacterial DNA Polymerase Ⅲ Alpha Subunits

    Institute of Scientific and Technical Information of China (English)

    Xiao-Qian Zhao; Jian-Fei Hu; Jun Yu

    2006-01-01

    DNA polymerase Ⅲ is one of the five eubacterial DNA polymerases that is responsible for the replication of DNA duplex. Among the ten subunits of the DNA polymerase Ⅲ core enzyme, the alpha subunit catalyzes the reaction for polymerizing both DNA strands. In this study, we extracted genomic sequences of the alpha subunit from 159 sequenced eubacterial genomes, and carried out sequencebased phylogenetic and structural analyses. We found that all eubacterial genomes have one or more alpha subunits, which form either homodimers or heterodimers.Phylogenetic and domain structural analyses as well as copy number variations of the alpha subunit in each bacterium indicate the classification of alpha subunit into four basic groups: polC, dnaE1, dnaE2, and dnaE3. This classification is of essence in genome composition analysis. We also consolidated the naming convention to avoid further confusion in gene annotations.

  12. The effect of polylysine on casein-kinase-2 activity is influenced by both the structure of the protein/peptide substrates and the subunit composition of the enzyme

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Marin, O;

    1992-01-01

    alpha subunit. The concentration of polylysine required for half-maximal stimulation is comparable to CK2 concentration and increases by increasing CK2 concentration, suggesting that polylysine primarily interacts with the enzyme, rather than with the peptide substrate.......The mechanism by which polybasic peptides stimulate the activity of casein kinase 2 (CK2) has been studied by comparing the effect of polylysine on the phosphorylation of a variety of protein and peptide substrates by the native CK2 holoenzyme and by its recombinant catalytic alpha subunit, either...... phosphorylated by either CK2 holoenzyme or the recombinant alpha subunit with 5.8-fold and 2.8-fold stimulation by polylysine, respectively. The recombinant beta subunit of CK2 is itself a good exogenous substrate for the enzyme, its phosphorylation, however, is inhibited rather than enhanced by polylysine...

  13. Diversity of heterotrimeric G-protein γ subunits in plants

    Directory of Open Access Journals (Sweden)

    Trusov Yuri

    2012-10-01

    Full Text Available Abstract Background Heterotrimeric G-proteins, consisting of three subunits Gα, Gβ and Gγ are present in most eukaryotes and mediate signaling in numerous biological processes. In plants, Gγ subunits were shown to provide functional selectivity to G-proteins. Three unconventional Gγ subunits were recently reported in Arabidopsis, rice and soybean but no structural analysis has been reported so far. Their relationship with conventional Gγ subunits and taxonomical distribution has not been yet demonstrated. Results After an extensive similarity search through plant genomes, transcriptomes and proteomes we assembled over 200 non-redundant proteins related to the known Gγ subunits. Structural analysis of these sequences revealed that most of them lack the obligatory C-terminal prenylation motif (CaaX. According to their C-terminal structures we classified the plant Gγ subunits into three distinct types. Type A consists of Gγ subunits with a putative prenylation motif. Type B subunits lack a prenylation motif and do not have any cysteine residues in the C-terminal region, while type C subunits contain an extended C-terminal domain highly enriched with cysteines. Comparative analysis of C-terminal domains of the proteins, intron-exon arrangement of the corresponding genes and phylogenetic studies suggested a common origin of all plant Gγ subunits. Conclusion Phylogenetic analyses suggest that types C and B most probably originated independently from type A ancestors. We speculate on a potential mechanism used by those Gγ subunits lacking isoprenylation motifs to anchor the Gβγ dimer to the plasma membrane and propose a new flexible nomenclature for plant Gγ subunits. Finally, in the light of our new classification, we give a word of caution about the interpretation of Gγ research in Arabidopsis and its generalization to other plant species.

  14. Subunit structure of the phycobiliproteins of blue-green algae.

    Science.gov (United States)

    Glazer, A N; Cohen-Bazire, G

    1971-07-01

    The phycobiliproteins of the blue-green algae Synechococcus sp. and Aphanocapsu sp. were characterized with respect to homogeneity, isoelectric point, and subunit composition. Each of the biliproteins consisted of two different noncovalently associated subunits, with molecular weights of about 20,000 and 16,000 for phycocyanin, 17,500 and 15,500 for allophycocyanin, and 22,000 and 20,000 for phycoerythrin. Covalently bound chromophore was associated with each subunit.

  15. Photolabeling of Glu-129 of the S-1 subunit of pertussis toxin with NAD

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, J.T.; Mende-Mueller, L.M.; Rappuoli, R.; Collier, R.J. (Medical College of Wisconsin, Milwaukee (USA))

    1989-11-01

    UV irradiation was shown to induce efficient transfer of radiolabel from nicotinamide-labeled NAD to a recombinant protein (C180 peptide) containing the catalytic region of the S-1 subunit of pertussis toxin. Incorporation of label from (3H-nicotinamide)NAD was efficient (0.5 to 0.6 mol/mol of protein) relative to incorporation from (32P-adenylate)NAD (0.2 mol/mol of protein). Label from (3H-nicotinamide)NAD was specifically associated with Glu-129. Replacement of Glu-129 with glycine or aspartic acid made the protein refractory to photolabeling with (3H-nicotinamide)NAD, whereas replacement of a nearby glutamic acid, Glu-139, with serine did not. Photolabeling of the C180 peptide with NAD is similar to that observed with diphtheria toxin and exotoxin A of Pseudomonas aeruginosa, in which the nicotinamide portion of NAD is transferred to Glu-148 and Glu-553, respectively, in the two toxins. These results implicate Glu-129 of the S-1 subunit as an active-site residue and a potentially important site for genetic modification of pertussis toxin for development of an acellular vaccine against Bordetella pertussis.

  16. Cloning and characterization of GST fusion tag stabilized large subunit of Escherichia coli acetohydroxyacid synthase I.

    Science.gov (United States)

    Li, Heng; Liu, Nan; Wang, Wen-Ting; Wang, Ji-Yu; Gao, Wen-Yun

    2016-01-01

    There are three acetohydroxyacid synthase (AHAS, EC 4.1.3.18) isozymes (I, II, and III) in the enterobacteria Escherichia coli among which AHAS I is the most active. Its large subunit (LSU) possesses full catalytic machinery, but is unstable in the absence of the small subunit (SSU). To get applicable LSU of AHAS I, we prepared and characterized in this study the polypeptide as a His-tagged (His-LSU) and a glutathione S-transferase (GST)-tagged (GST-LSU) fusion protein, respectively. The results showed that the His-LSU is unstable, whereas the GST-LSU displays excellent stability. This phenomenon suggests that the GST polypeptide fusion tag could stabilize the target protein when compared with histidine tag. It is the first time that the stabilizing effect of the GST tag was observed. Further characterization of the GST-LSU protein indicated that it possesses the basic functions of AHAS I with a specific activity of 20.8 μmol min(-1) mg(-1) and a Km value for pyruvate of 0.95 mM. These observations imply that introduction of the GST fusion tag to LSU of AHAS I does not affect the function of the protein. The possible reasons that the GST fusion tag could make the LSU stable are initially discussed.

  17. Role of calmodulin (δ-subunit) in activation of phosphorylase kinase from rabbit skeletal muscles

    International Nuclear Information System (INIS)

    The structure of the inactivated and activated forms of phospholyase kinase was compared. The enzyme was activated by incubation in an alkaline medium (pH 8.5), phosphorylation of the catalytic subunit of cAMP-dependent protein kinase, and limited proteolysis. Hydrophobic chromatography on phenyl-Sepharose and electrophoresis in a polyacrylamide gel density gradient were employed for a comparison of these forms of the enzyme. Activation of the enzyme was accompanied by the separation of a low-molecular-weight component (M/sub r/ about 17,000). The low-molecular-weight protein was obtained in a homogeneous state by chromatography on phenyl-Sepharose. It was established that its properties are similar to those of calmodulin. The presence of calmodulin in preparations of phosphorylase kinase was judged by the activation of the calmodulin-dependent form of phosphodiesterase. The boiled and subtilisin-treated kinase activates phosphodiesterase in much the same way as bovine brain calmodulin. The results obtained suggest that the δ-subunit is a protein inhibitor of the enzyme

  18. Protein phosphatase 2A subunit PR70 interacts with pRb and mediates its dephosphorylation.

    Science.gov (United States)

    Magenta, Alessandra; Fasanaro, Pasquale; Romani, Sveva; Di Stefano, Valeria; Capogrossi, Maurizio C; Martelli, Fabio

    2008-01-01

    The retinoblastoma tumor suppressor protein (pRb) regulates cell proliferation and differentiation via phosphorylation-sensitive interactions with specific targets. While the role of cyclin/cyclin-dependent kinase complexes in the modulation of pRb phosphorylation has been extensively studied, relatively little is known about the molecular mechanisms regulating phosphate removal by phosphatases. Protein phosphatase 2A (PP2A) is constituted by a core dimer bearing catalytic activity and one variable B regulatory subunit conferring target specificity and subcellular localization. We previously demonstrated that PP2A core dimer binds pRb and dephosphorylates pRb upon oxidative stress. In the present study, we identified a specific PP2A-B subunit, PR70, that was associated with pRb both in vitro and in vivo. PR70 overexpression caused pRb dephosphorylation; conversely, PR70 knockdown prevented both pRb dephosphorylation and DNA synthesis inhibition induced by oxidative stress. Moreover, we found that intracellular Ca(2+) mobilization was necessary and sufficient to trigger pRb dephosphorylation and PP2A phosphatase activity of PR70 was Ca(2+) induced. These data underline the importance of PR70-Ca(2+) interaction in the signal transduction mechanisms triggered by redox imbalance and leading to pRb dephosphorylation.

  19. Catalytic Fast Pyrolysis: A Review

    Directory of Open Access Journals (Sweden)

    Theodore Dickerson

    2013-01-01

    Full Text Available Catalytic pyrolysis is a promising thermochemical conversion route for lignocellulosic biomass that produces chemicals and fuels compatible with current, petrochemical infrastructure. Catalytic modifications to pyrolysis bio-oils are geared towards the elimination and substitution of oxygen and oxygen-containing functionalities in addition to increasing the hydrogen to carbon ratio of the final products. Recent progress has focused on both hydrodeoxygenation and hydrogenation of bio-oil using a variety of metal catalysts and the production of aromatics from bio-oil using cracking zeolites. Research is currently focused on developing multi-functional catalysts used in situ that benefit from the advantages of both hydrodeoxygenation and zeolite cracking. Development of robust, highly selective catalysts will help achieve the goal of producing drop-in fuels and petrochemical commodities from wood and other lignocellulosic biomass streams. The current paper will examine these developments by means of a review of existing literature.

  20. Specific Mutations in Mammalian P4-ATPase ATP8A2 Catalytic Subunit Entail Differential Glycosylation of the Accessory CDC50A Subunit

    DEFF Research Database (Denmark)

    Vestergaard, Anna L.; Mikkelsen, Stine A.; Coleman, Jonathan A.;

    2015-01-01

    P4-ATPases, or flippases, translocate phospholipids between the two leaflets of eukaryotic biological membranes. They are essential to the physiologically crucial phospholipid asymmetry and involved in severe diseases, but their molecular structure and mechanism are still unresolved. Here, we sho...

  1. Dynamic regulation of β1 subunit trafficking controls vascular contractility

    Science.gov (United States)

    Leo, M. Dennis; Bannister, John P.; Narayanan, Damodaran; Nair, Anitha; Grubbs, Jordan E.; Gabrick, Kyle S.; Boop, Frederick A.; Jaggar, Jonathan H.

    2014-01-01

    Ion channels composed of pore-forming and auxiliary subunits control physiological functions in virtually all cell types. A conventional view is that channels assemble with their auxiliary subunits before anterograde plasma membrane trafficking of the protein complex. Whether the multisubunit composition of surface channels is fixed following protein synthesis or flexible and open to acute and, potentially, rapid modulation to control activity and cellular excitability is unclear. Arterial smooth muscle cells (myocytes) express large-conductance Ca2+-activated potassium (BK) channel α and auxiliary β1 subunits that are functionally significant modulators of arterial contractility. Here, we show that native BKα subunits are primarily (∼95%) plasma membrane-localized in human and rat arterial myocytes. In contrast, only a small fraction (∼10%) of total β1 subunits are located at the cell surface. Immunofluorescence resonance energy transfer microscopy demonstrated that intracellular β1 subunits are stored within Rab11A-postive recycling endosomes. Nitric oxide (NO), acting via cGMP-dependent protein kinase, and cAMP-dependent pathways stimulated rapid (≤1 min) anterograde trafficking of β1 subunit-containing recycling endosomes, which increased surface β1 almost threefold. These β1 subunits associated with surface-resident BKα proteins, elevating channel Ca2+ sensitivity and activity. Our data also show that rapid β1 subunit anterograde trafficking is the primary mechanism by which NO activates myocyte BK channels and induces vasodilation. In summary, we show that rapid β1 subunit surface trafficking controls functional BK channel activity in arterial myocytes and vascular contractility. Conceivably, regulated auxiliary subunit trafficking may control ion channel activity in a wide variety of cell types. PMID:24464482

  2. Cyclic AMP-dependent protein kinase (cAPK) regulatory subunits are packaged and secreted by many exocrine and endocrine cells

    Energy Technology Data Exchange (ETDEWEB)

    Mednieks, M.I.; Hand, A.R.

    1986-05-01

    Regulatory (R) subunits of cAPK were identified by us as components of rat and human saliva by photoaffinity labeling with (/sup 32/P)-8-azido cyclic AMP. Photoaffinity labeling of purified rat parotid granule contents and immunogold labeling of thin sections with monoclonal antibodies showed the presence of R subunits in granules. The authors now report that cAPK R subunits are present in secretory granules and are apparently secreted by many exocrine and endocrine cell types. Labeling of thin sections of rat tissues with antibody to R subunits and protein A-gold shows gold particles over secretory granules of endocrine cells of the pituitary, pancreas and intestine. Zymogen granules of exocrine pancreatic acinar cells, the dense cores of secretory granules of seminal vesicle epithelial cells and secretory product in the seminal vesicle lumina were prominently labeled with gold. Photoaffinity labeling shows that pancreatic secretions and seminal vesicle contents have cAPK components. Phosphorylative modification of cellular proteins by cAMP controls hormonally stimulated protein secretion by many cell types. Although no catalytic activity was detected, identification of R subunits in granules and as secretory products indicates that they may have multiple roles in cellular mechanisms of action of cyclic AMP-mediated events in secretory cells.

  3. Crystallization of the glycogen-binding domain of the AMP-activated protein kinase β subunit and preliminary X-ray analysis

    Energy Technology Data Exchange (ETDEWEB)

    Polekhina, Galina, E-mail: gpolekhina@svi.edu.au; Feil, Susanne C.; Gupta, Abhilasha [St Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065 (Australia); O’Donnell, Paul [Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville 3010 (Australia); Stapleton, David; Parker, Michael W. [St Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3065 (Australia)

    2005-01-01

    The glycogen-binding domain of the AMP-activated kinase β subunit has been crystallized in the presence of β-cyclodextrin. The structure has been determined by single isomorphous replacement and threefold averaging using in-house X-ray data collected from selenomethionine-substituted protein. AMP-activated protein kinase (AMPK) is an intracellular energy sensor that regulates metabolism in response to energy demand and supply by adjusting the ATP-generating and ATP-consuming pathways. AMPK potentially plays a critical role in diabetes and obesity as it is known to be activated by metforin and rosiglitazone, drugs used for the treatment of type II diabetes. AMPK is a heterotrimer composed of a catalytic α subunit and two regulatory subunits, β and γ. Mutations in the γ subunit are known to cause glycogen accumulation, leading to cardiac arrhythmias. Recently, a functional glycogen-binding domain (GBD) has been identified in the β subunit. Here, the crystallization of GBD in the presence of β-cyclodextrin is reported together with preliminary X-ray data analysis allowing the determination of the structure by single isomorphous replacement and threefold averaging using in-house X-ray data collected from a selenomethionine-substituted protein.

  4. Combined catalytic converter and afterburner

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-30

    This patent describes the combined use of a catalytic converter and afterburner. An afterburner chamber and a catalyst matrix are disposed in series within a casing. A combustible premixed charge is ignited in the afterburner chamber before it enters the catalyst matrix. This invention overcomes the problem encountered in previous designs of some of the premixed charge passing unreacted through the device unless a very long afterburner chamber is used. (UK)

  5. Liposome-Based Adjuvants for Subunit Vaccines: Formulation Strategies for Subunit Antigens and Immunostimulators

    DEFF Research Database (Denmark)

    Schmidt, Signe Tandrup; Foged, Camilla; Korsholm, Karen Smith;

    2016-01-01

    be classified into delivery systems or immunostimulators. Liposomes are versatile delivery systems for antigens, and they can carefully be customized towards desired immune profiles by combining them with immunostimulators and optimizing their composition, physicochemical properties and antigen-loading mode...... for which no effective vaccines exist. The subunit vaccine technology exploits pathogen subunits as antigens, e.g., recombinant proteins or synthetic peptides, allowing for highly specific immune responses against the pathogens. However, such antigens are usually not sufficiently immunogenic to induce...... protective immunity, and they are often combined with adjuvants to ensure robust immune responses. Adjuvants are capable of enhancing and/or modulating immune responses by exposing antigens to antigen-presenting cells (APCs) concomitantly with conferring immune activation signals. Few adjuvant systems have...

  6. Thermodynamics of catalytic nanoparticle morphology

    Science.gov (United States)

    Zwolak, Michael; Sharma, Renu; Lin, Pin Ann

    Metallic nanoparticles are an important class of industrial catalysts. The variability of their properties and the environment in which they act, from their chemical nature & surface modification to their dispersion and support, allows their performance to be optimized for many chemical processes useful in, e.g., energy applications and other areas. Their large surface area to volume ratio, as well as varying sizes and faceting, in particular, makes them an efficient source for catalytically active sites. These characteristics of nanoparticles - i.e., their morphology - can often display intriguing behavior as a catalytic process progresses. We develop a thermodynamic model of nanoparticle morphology, one that captures the competition of surface energy with other interactions, to predict structural changes during catalytic processes. Comparing the model to environmental transmission electron microscope images of nickel nanoparticles during carbon nanotube (and other product) growth demonstrates that nickel deformation in response to the nanotube growth is due to a favorable interaction with carbon. Moreover, this deformation is halted due to insufficient volume of the particles. We will discuss the factors that influence morphology and also how the model can be used to extract interaction strengths from experimental observations.

  7. Activities of human RRP6 and structure of the human RRP6 catalytic domain

    Energy Technology Data Exchange (ETDEWEB)

    Januszyk, Kurt; Liu, Quansheng; Lima, Christopher D. (SKI)

    2011-08-29

    The eukaryotic RNA exosome is a highly conserved multi-subunit complex that catalyzes degradation and processing of coding and noncoding RNA. A noncatalytic nine-subunit exosome core interacts with Rrp44 and Rrp6, two subunits that possess processive and distributive 3'-to-5' exoribonuclease activity, respectively. While both Rrp6 and Rrp44 are responsible for RNA processing in budding yeast, Rrp6 may play a more prominent role in processing, as it has been demonstrated to be inhibited by stable RNA secondary structure in vitro and because the null allele in budding yeast leads to the buildup of specific structured RNA substrates. Human RRP6, otherwise known as PM/SCL-100 or EXOSC10, shares sequence similarity to budding yeast Rrp6 and is proposed to catalyze 3'-to-5' exoribonuclease activity on a variety of nuclear transcripts including ribosomal RNA subunits, RNA that has been poly-adenylated by TRAMP, as well as other nuclear RNA transcripts destined for processing and/or destruction. To characterize human RRP6, we expressed the full-length enzyme as well as truncation mutants that retain catalytic activity, compared their activities to analogous constructs for Saccharomyces cerevisiae Rrp6, and determined the X-ray structure of a human construct containing the exoribonuclease and HRDC domains that retains catalytic activity. Structural data show that the human active site is more exposed when compared to the yeast structure, and biochemical data suggest that this feature may play a role in the ability of human RRP6 to productively engage and degrade structured RNA substrates more effectively than the analogous budding yeast enzyme.

  8. Liposome-Based Adjuvants for Subunit Vaccines: Formulation Strategies for Subunit Antigens and Immunostimulators

    Directory of Open Access Journals (Sweden)

    Signe Tandrup Schmidt

    2016-03-01

    Full Text Available The development of subunit vaccines has become very attractive in recent years due to their superior safety profiles as compared to traditional vaccines based on live attenuated or whole inactivated pathogens, and there is an unmet medical need for improved vaccines and vaccines against pathogens for which no effective vaccines exist. The subunit vaccine technology exploits pathogen subunits as antigens, e.g., recombinant proteins or synthetic peptides, allowing for highly specific immune responses against the pathogens. However, such antigens are usually not sufficiently immunogenic to induce protective immunity, and they are often combined with adjuvants to ensure robust immune responses. Adjuvants are capable of enhancing and/or modulating immune responses by exposing antigens to antigen-presenting cells (APCs concomitantly with conferring immune activation signals. Few adjuvant systems have been licensed for use in human vaccines, and they mainly stimulate humoral immunity. Thus, there is an unmet demand for the development of safe and efficient adjuvant systems that can also stimulate cell-mediated immunity (CMI. Adjuvants constitute a heterogeneous group of compounds, which can broadly be classified into delivery systems or immunostimulators. Liposomes are versatile delivery systems for antigens, and they can carefully be customized towards desired immune profiles by combining them with immunostimulators and optimizing their composition, physicochemical properties and antigen-loading mode. Immunostimulators represent highly diverse classes of molecules, e.g., lipids, nucleic acids, proteins and peptides, and they are ligands for pattern-recognition receptors (PRRs, which are differentially expressed on APC subsets. Different formulation strategies might thus be required for incorporation of immunostimulators and antigens, respectively, into liposomes, and the choice of immunostimulator should ideally be based on knowledge regarding the

  9. PiZ mouse liver accumulates polyubiquitin conjugates that associate with catalytically active 26S proteasomes.

    Directory of Open Access Journals (Sweden)

    Christopher J Haddock

    Full Text Available Accumulation of aggregation-prone human alpha 1 antitrypsin mutant Z (AT-Z protein in PiZ mouse liver stimulates features of liver injury typical of human alpha 1 antitrypsin type ZZ deficiency, an autosomal recessive genetic disorder. Ubiquitin-mediated proteolysis by the 26S proteasome counteracts AT-Z accumulation and plays other roles that, when inhibited, could exacerbate the injury. However, it is unknown how the conditions of AT-Z mediated liver injury affect the 26S proteasome. To address this question, we developed a rapid extraction strategy that preserves polyubiquitin conjugates in the presence of catalytically active 26S proteasomes and allows their separation from deposits of insoluble AT-Z. Compared to WT, PiZ extracts had about 4-fold more polyubiquitin conjugates with no apparent change in the levels of the 26S and 20S proteasomes, and unassembled subunits. The polyubiquitin conjugates had similar affinities to ubiquitin-binding domain of Psmd4 and co-purified with similar amounts of catalytically active 26S complexes. These data show that polyubiquitin conjugates were accumulating despite normal recruitment to catalytically active 26S proteasomes that were available in excess, and suggest that a defect at the 26S proteasome other than compromised binding to polyubiquitin chain or peptidase activity played a role in the accumulation. In support of this idea, PiZ extracts were characterized by high molecular weight, reduction-sensitive forms of selected subunits, including ATPase subunits that unfold substrates and regulate access to proteolytic core. Older WT mice acquired similar alterations, implying that they result from common aspects of oxidative stress. The changes were most pronounced on unassembled subunits, but some subunits were altered even in the 26S proteasomes co-purified with polyubiquitin conjugates. Thus, AT-Z protein aggregates indirectly impair degradation of polyubiquitinated proteins at the level of the 26S

  10. Proteopedia Entry: The Large Ribosomal Subunit of "Haloarcula Marismortui"

    Science.gov (United States)

    Decatur, Wayne A.

    2010-01-01

    This article presents a "Proteopedia" page that shows the refined version of the structure of the "Haloarcula" large ribosomal subunit as solved by the laboratories of Thomas Steitz and Peter Moore. The landmark structure is of great impact as it is the first atomic-resolution structure of the highly conserved ribosomal subunit which harbors…

  11. Regulation of Glutamate Receptors by Their Auxiliary Subunits

    OpenAIRE

    Tomita, Susumu

    2010-01-01

    Glutamate receptors are major excitatory receptors in the brain. Recent findings have established auxiliary subunits of glutamate receptors as critical modulators of synaptic transmission, synaptic plasticity and neurological disorder. The elucidation of the molecular rules governing glutamate receptors and subunits will improve our understanding of synapses and of neural-circuit regulation in the brain.

  12. Moving Iron through ferritin protein nanocages depends on residues throughout each four α-helix bundle subunit.

    Science.gov (United States)

    Haldar, Suranjana; Bevers, Loes E; Tosha, Takehiko; Theil, Elizabeth C

    2011-07-22

    Eukaryotic H ferritins move iron through protein cages to form biologically required, iron mineral concentrates. The biominerals are synthesized during protein-based Fe²⁺/O₂ oxidoreduction and formation of [Fe³⁺O](n) multimers within the protein cage, en route to the cavity, at sites distributed over ~50 Å. Recent NMR and Co²⁺-protein x-ray diffraction (XRD) studies identified the entire iron path and new metal-protein interactions: (i) lines of metal ions in 8 Fe²⁺ ion entry channels with three-way metal distribution points at channel exits and (ii) interior Fe³⁺O nucleation channels. To obtain functional information on the newly identified metal-protein interactions, we analyzed effects of amino acid substitution on formation of the earliest catalytic intermediate (diferric peroxo-A(650 nm)) and on mineral growth (Fe³⁺O-A(350 nm)), in A26S, V42G, D127A, E130A, and T149C. The results show that all of the residues influenced catalysis significantly (p access/selectivity to the active sites (Glu¹³⁰), (ii) distribution of Fe²⁺ to each of the three active sites near each ion channel (Asp¹²⁷), (iii) product (diferric oxo) release into the Fe³⁺O nucleation channels (Ala²⁶), and (iv) [Fe³⁺O](n) transit through subunits (Val⁴², Thr¹⁴⁹). Synthesis of ferritin biominerals depends on residues along the entire length of H subunits from Fe²⁺ substrate entry at 3-fold cage axes at one subunit end through active sites and nucleation channels, at the other subunit end, inside the cage at 4-fold cage axes. Ferritin subunit-subunit geometry contributes to mineral order and explains the physiological impact of ferritin H and L subunits. PMID:21592958

  13. Structural properties of cyanase. Denaturation, renaturation, and role of sulfhydryls and oligomeric structure in catalytic activity.

    Science.gov (United States)

    Little, R M; Anderson, P M

    1987-07-25

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes bicarbonate-dependent decomposition of cyanate to give ammonia and bicarbonate. The enzyme is composed of 8-10 identical subunits (Mr = 17,008). The objective of this study was to clarify some of the structural properties of cyanase for the purpose of understanding the relationship between oligomeric structure and catalytic activity. Circular dichroism studies showed that cyanase has a significant amount of alpha-helix and beta-sheet structure. The one sulfhydryl group per subunit does not react with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) unless cyanase is denatured. Denaturation is apparently complete in 10 M urea or 6 M guanidine hydrochloride, but is significantly reduced in 10 M urea by the presence of azide (analog of cyanate) and is incomplete in 8 M urea. Denatured cyanase could be renatured and reactivated (greater than 85%) by removal of denaturants. Reactivation was greatly facilitated by the presence of certain anions, particularly bicarbonate, and by high ionic strength and protein concentration. The catalytic activity of renatured cyanase was associated only with oligomer. Cyanase that had been denatured in the presence of DTNB to give a cyanase-DTNB derivative could also be renatured at 26 degrees C to give active cyanase-DTNB oligomer. The active oligomeric form of the cyanase-DTNB derivative could be converted reversibly to inactive dimer by lowering the temperature to 4 degrees C or by reduction of the ionic strength and removal of monoanions. These results provide evidence that free sulfhydryl groups are not required for catalytic activity and that catalytic activity may be dependent upon oligomeric structure.

  14. Identification of a novel HMW glutenin subunit and comparison of its amino acid sequence with those of homologous subunits

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Aegilops tauschii is the donor of the D genome of common wheat (Triticum aestivum). Genetic variation of HMW glutenin subunits encoded by the Glu-1Dt locus of Ae. tauschii has been found to be higher than that specified by the Glu-1D locus in common wheat. In the present note, we report the identification of a novel HMW glutenin subunit, Dy13t, from Ae. tauschii. The newly identified subunit possessed an electrophoretic mobility that was faster than that of the Dy12 subunit of common wheat. The complete ORF of encoding the Dy13t subunit contained 624 codons (excluding the stop codons). The amino acid sequence deduced from the Dy13t gene ORF was the shortest among those of the previously reported subunits derived by the D genome. A further comparison of Dy13t amino acid sequence with those of the subunits characterized from the A, B, D, R genomes of Triticeae showed that the smaller size of the Dy13t subunit was associated with a reduction in the size of its repetitive domain.

  15. Nonfouling hydrogels formed from charged monomer subunits.

    Science.gov (United States)

    Dobbins, Sean C; McGrath, Daniel E; Bernards, Matthew T

    2012-12-13

    A critical challenge in the field of biomaterials is the often undesirable, but immediate, coating of implants with nonspecifically adsorbed proteins upon contact with bodily fluids. Prior research has shown that overall neutral materials containing a homologous arrangement of mixed charges exhibit nonfouling properties. This has been widely demonstrated for zwitterionic materials and more recently for coatings containing an equimolar mixture of positively and negatively charged monomer subunits. In this investigation it is demonstrated that nonfouling hydrogels can be formed through this approach, and the physical properties of the resulting materials are thoroughly characterized. In particular, hydrogels were formed from mixtures of [2-(methacryloyloxy)ethyl]trimethylammonium chloride (TM) and 3-sulfopropyl methacrylate potassium salt (SA) monomers with varying concentrations of a triethylene glycol dimethacrylate (TEGDMA) cross-linker. The swelling, weight percentage water, surface zeta potential, and compressional properties of the gels were characterized, and the nonfouling properties were demonstrated using enzyme-linked immunosorbant assays for both negatively charged fibrinogen and positively charged lysozyme. The results confirm that the TM:SA hydrogel systems have nonfouling properties that are equivalent to established nonfouling controls. Additionally, even though the gels were resistant to nonspecific protein adsorption, a composition analysis suggests that there is room to further improve the nonfouling performance because there is a slight enrichment of the SA monomer relative to the TM monomer. PMID:23189949

  16. Gel-based chemical cross-linking analysis of 20S proteasome subunit-subunit interactions in breast cancer.

    Science.gov (United States)

    Song, Hai; Xiong, Hua; Che, Jing; Xi, Qing-Song; Huang, Liu; Xiong, Hui-Hua; Zhang, Peng

    2016-08-01

    The ubiquitin-proteasome system plays a pivotal role in breast tumorigenesis by controlling transcription factors, thus promoting cell cycle growth, and degradation of tumor suppressor proteins. However, breast cancer patients have failed to benefit from proteasome inhibitor treatment partially due to proteasome heterogeneity, which is poorly understood in malignant breast neoplasm. Chemical crosslinking is an increasingly important tool for mapping protein three-dimensional structures and proteinprotein interactions. In the present study, two cross-linkers, bis (sulfosuccinimidyl) suberate (BS(3)) and its water-insoluble analog disuccinimidyl suberate (DSS), were used to map the subunit-subunit interactions in 20S proteasome core particle (CP) from MDA-MB-231 cells. Different types of gel electrophoresis technologies were used. In combination with chemical cross-linking and mass spectrometry, we applied these gel electrophoresis technologies to the study of the noncovalent interactions among 20S proteasome subunits. Firstly, the CP subunit isoforms were profiled. Subsequently, using native/SDSPAGE, it was observed that 0.5 mmol/L BS(3) was a relatively optimal cross-linking concentration for CP subunit-subunit interaction study. 2-DE analysis of the cross-linked CP revealed that α1 might preinteract with α2, and α3 might pre-interact with α4. Moreover, there were different subtypes of α1α2 and α3α4 due to proteasome heterogeneity. There was no significant difference in cross-linking pattern for CP subunits between BS(3) and DSS. Taken together, the gel-based characterization in combination with chemical cross-linking could serve as a tool for the study of subunit interactions within a multi-subunit protein complex. The heterogeneity of 20S proteasome subunit observed in breast cancer cells may provide some key information for proteasome inhibition strategy. PMID:27465334

  17. Kinetics of heterogeneous catalytic reactions

    CERN Document Server

    Boudart, Michel

    2014-01-01

    This book is a critical account of the principles of the kinetics of heterogeneous catalytic reactions in the light of recent developments in surface science and catalysis science. Originally published in 1984. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase acc

  18. Molecular catalytic coal liquid conversion

    Energy Technology Data Exchange (ETDEWEB)

    Stock, L.M.; Yang, Shiyong [Univ. of Chicago, IL (United States)

    1995-12-31

    This research, which is relevant to the development of new catalytic systems for the improvement of the quality of coal liquids by the addition of dihydrogen, is divided into two tasks. Task 1 centers on the activation of dihydrogen by molecular basic reagents such as hydroxide ion to convert it into a reactive adduct (OH{center_dot}H{sub 2}){sup {minus}} that can reduce organic molecules. Such species should be robust withstanding severe conditions and chemical poisons. Task 2 is focused on an entirely different approach that exploits molecular catalysts, derived from organometallic compounds that are capable of reducing monocyclic aromatic compounds under very mild conditions. Accomplishments and conclusions are discussed.

  19. Computational Introduction of Catalytic Activity into Proteins.

    Science.gov (United States)

    Bertolani, Steve J; Carlin, Dylan Alexander; Siegel, Justin B

    2016-01-01

    Recently, there have been several successful cases of introducing catalytic activity into proteins. One method that has been used successfully to achieve this is the theozyme placement and enzyme design algorithms implemented in Rosetta Molecular Modeling Suite. Here, we illustrate how to use this software to recapitulate the placement of catalytic residues and ligand into a protein using a theozyme, protein scaffold, and catalytic constraints as input. PMID:27094294

  20. Estimating the temperature of a catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-02

    A method is described for estimating the temperature in a catalytic converter used in the exhaust system of an internal combustion engine. Pressure sensors monitor the flow resistance across the catalytic converter to provide an indication of the temperature inside. This feedback system allows heating devices to be switched off and thus avoid overheating, while maintaining the catalytic converter's efficiency by assuring that it does not operate below its light off temperature. (UK)

  1. Estimating the temperature of a catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-11-02

    A method of estimating the temperature of a catalytic converter used in the exhaust system of an internal combustion engine is described. Heated exhaust gas oxygen (HEGO) sensors are placed upstream and downstream of the catalytic converter. The temperature of the catalytic converter shortly after start-up is measured by monitoring the resistance of the HEGO sensor's heating element. The downstream sensor is used for mixture control and to double check results of the upstream sensor. (UK)

  2. Some Aspects of the Catalytic Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Anil; K.Saikia

    2007-01-01

    1 Results Catalytic reactions are gaining importance due to its low cost, operational simplicity, high efficiency and selectivity. It is also getting much attention in green synthesis. Many useful organic reactions, including the acylation of alcohols and aldehydes, carbon-carbon, carbon-nitrogen, carbon-sulfur bond forming and oxidation reactions are carried out by catalyst. We are exploring the catalytic acylation of alcohols and aldehydes in a simple and efficient manner. Catalytic activation of unr...

  3. Conservation of helical bundle structure between the exocyst subunits.

    Directory of Open Access Journals (Sweden)

    Nicole J Croteau

    Full Text Available BACKGROUND: The exocyst is a large hetero-octomeric protein complex required for regulating the targeting and fusion of secretory vesicles to the plasma membrane in eukaryotic cells. Although the sequence identity between the eight different exocyst subunits is less than 10%, structures of domains of four of the subunits revealed a similar helical bundle topology. Characterization of several of these subunits has been hindered by lack of soluble protein for biochemical and structural studies. METHODOLOGY/PRINCIPAL FINDINGS: Using advanced hidden Markov models combined with secondary structure predictions, we detect significant sequence similarity between each of the exocyst subunits, indicating that they all contain helical bundle structures. We corroborate these remote homology predictions by identifying and purifying a predicted domain of yeast Sec10p, a previously insoluble exocyst subunit. This domain is soluble and folded with approximately 60% alpha-helicity, in agreement with our predictions, and capable of interacting with several known Sec10p binding partners. CONCLUSIONS/SIGNIFICANCE: Although all eight of the exocyst subunits had been suggested to be composed of similar helical bundles, this has now been validated by our hidden Markov model structure predictions. In addition, these predictions identified protein domains within the exocyst subunits, resulting in creation and characterization of a soluble, folded domain of Sec10p.

  4. Overexpression of stress-inducible OsBURP16, the β subunit of polygalacturonase 1, decreases pectin content and cell adhesion and increases abiotic stress sensitivity in rice.

    Science.gov (United States)

    Liu, Huanhuan; Ma, Yan; Chen, Na; Guo, Siyi; Liu, Huili; Guo, Xiaoyu; Chong, Kang; Xu, Yunyuan

    2014-05-01

    Polygalacturonase (PG), one of the hydrolases responsible for cell wall pectin degradation, is involved in organ consenescence and biotic stress in plants. PG1 is composed of a catalytic subunit, PG2, and a non-catalytic PG1β subunit. OsBURP16 belongs to the PG1β-like subfamily of BURP-family genes and encodes one putative PG1β subunit precursor in rice (Oryza sativa L.). Transcription of OsBURP16 is induced by cold, salinity and drought stresses, as well as by abscisic acid (ABA) treatment. Analysis of plant survival rates, relative ion leakage rates, accumulation levels of H2 O2 and water loss rates of leaves showed that overexpression of OsBURP16 enhanced sensitivity to cold, salinity and drought stresses compared with controls. Young leaves of Ubi::OsBURP16 transgenic plants showed reduced cell adhesion and increased cuticular transpiration rate. Mechanical strength measurement of Ubi::OsBURP16 plants showed that reduced force was required to break leaves as compared with wild type. Transgenic rice showed enhanced PG activity and reduced pectin content. All these results suggested that overexpression of OsBURP16 caused pectin degradation and affected cell wall integrity as well as transpiration rate, which decreased tolerance to abiotic stresses. PMID:24237159

  5. Structure of the nucleotide-binding subunit B of the energy producer A1A0 ATP synthase in complex with adenosine diphosphate.

    Science.gov (United States)

    Kumar, Anil; Manimekalai, Malathy Sony Subramanian; Grüber, Gerhard

    2008-11-01

    A1A0 ATP synthases are the major energy producers in archaea. Like the related prokaryotic and eukaryotic F1F0 ATP synthases, they are responsible for most of the synthesis of adenosine triphosphate. The catalytic events of A1A0 ATP synthases take place inside the A3B3 hexamer of the A1 domain. Recently, the crystallographic structure of the nucleotide-free subunit B of Methanosarcina mazei Gö1 A1A0 ATP synthase has been determined at 1.5 A resolution. To understand more about the nucleotide-binding mechanism, a protocol has been developed to crystallize the subunit B-ADP complex. The crystallographic structure of this complex has been solved at 2.7 A resolution. The ADP occupies a position between the essential phosphate-binding loop and amino-acid residue Phe149, which are involved in the binding of the antibiotic efrapeptin in the related F1F0 ATP synthases. This trapped ADP location is about 13 A distant from its final binding site and is therefore called the transition ADP-binding position. In the trapped ADP position the structure of subunit B adopts a different conformation, mainly in its C-terminal domain and also in the final nucleotide-binding site of the central alphabeta-domain. This atomic model provides insight into how the substrate enters into the nucleotide-binding protein and thereby into the catalytic A3B3 domain. PMID:19020348

  6. Protein phosphatase 2A is regulated by PKCα-dependent phosphorylation of its targeting subunit B56α at Ser41

    DEFF Research Database (Denmark)

    Kirchhefer, Uwe; Heinick, Alexander; König, Simone;

    2014-01-01

    Protein phosphatase 2A (PP2A) is a family of multifunctional serine/threonine phosphatases consisting of a catalytic C, a structural A, and a regulatory B subunit. The substrate and therefore the functional specificity of PP2A are determined by the assembly of the enzyme complex with the appropri......Protein phosphatase 2A (PP2A) is a family of multifunctional serine/threonine phosphatases consisting of a catalytic C, a structural A, and a regulatory B subunit. The substrate and therefore the functional specificity of PP2A are determined by the assembly of the enzyme complex...... with the appropriate regulatory B subunit families, namely B55, B56, PR72 or PR93/PR110. It has been suggested that additional levels of regulating PP2A function may result from the phosphorylation of B56 isoforms. In this study, we identified a novel phosphorylation site at Ser41 of B56α. This phosphoamino acid...... inhibition was markedly increased by PKCα phosphorylation. PP2A activity was also reduced in HEK293 cells transfected with a B56α mutant, where serine-41 was replaced by aspartic acid, which mimics phosphorylation. More evidence for a functional role of PKCα-dependent phosphorylation of B56α was derived from...

  7. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  8. Nanostructured Catalytic Reactors for Air Purification Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase II project proposes the development of lightweight compact nanostructured catalytic reactors for air purification from toxic gaseous organic...

  9. Mutations in GABAA receptor subunits associated with genetic epilepsies.

    Science.gov (United States)

    Macdonald, Robert L; Kang, Jing-Qiong; Gallagher, Martin J

    2010-06-01

    Mutations in inhibitory GABAA receptor subunit genes (GABRA1, GABRB3, GABRG2 and GABRD) have been associated with genetic epilepsy syndromes including childhood absence epilepsy (CAE), juvenile myoclonic epilepsy (JME), pure febrile seizures (FS), generalized epilepsy with febrile seizures plus (GEFS+), and Dravet syndrome (DS)/severe myoclonic epilepsy in infancy (SMEI). These mutations are found in both translated and untranslated gene regions and have been shown to affect the GABAA receptors by altering receptor function and/or by impairing receptor biogenesis by multiple mechanisms including reducing subunit mRNA transcription or stability, impairing subunit folding, stability, or oligomerization and by inhibiting receptor trafficking. PMID:20308251

  10. Catalytic reforming feed characterisation technique

    Energy Technology Data Exchange (ETDEWEB)

    Larraz Mora, R.; Arvelo Alvarez, R. [Univ. of La Laguna, Chemical Engineering Dept., La Laguna (Spain)

    2002-09-01

    The catalytic reforming of naphtha is one of the major refinery processes, designed to increase the octane number of naphtha or to produce aromatics. The naphtha used as catalytic reformer feedstock usually contains a mixture of paraffins, naphthenes, and aromatics in the carbon number range C{sub 6} to C{sub 10}. The detailed chemical composition of the feed is necessary to predict the aromatics and hydrogen production as well as the operation severity. The analysis of feed naphtha is usually reported in terms of its ASTM distillation curve and API or specific gravity. Since reforming reactions are described in terms of lumped chemical species (paraffins, naphthenes and aromatics), a feed characterisation technique should be useful in order to predict reforming operating conditions and detect feed quality changes. Unfortunately online analyzer applications as cromatography or recently introduced naphtha NMR [1] are scarce in most of refineries. This work proposes an algorithmic characterisation method focusing on its main steps description. The method could help on the subjects previously described, finally a calculation example is shown. (orig.)

  11. Catalytic conversion of light alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  12. Identification, cloning and characterization of a novel 47 kDa murine PKA C subunit homologous to human and bovine Cβ2

    Directory of Open Access Journals (Sweden)

    Ørstavik Sigurd

    2006-08-01

    Full Text Available Abstract Background Two main genes encoding the catalytic subunits Cα and Cβ of cyclic AMP dependent protein kinase (PKA have been identified in all vertebrates examined. The murine, bovine and human Cβ genes encode several splice variants, including the splice variant Cβ2. In mouse Cβ2 has a relative molecular mass of 38 kDa and is only expressed in the brain. In human and bovine Cβ2 has a relative molecular mass of 47 kDa and is mainly expressed in lymphoid tissues. Results We identified a novel 47 kDa splice variant encoded by the mouse Cβ gene that is highly expressed in lymphoid cells. Cloning, expression, and production of a sequence-specific antiserum and characterization of PKA catalytic subunit activities demonstrated the 47 kDa protein to be a catalytically active murine homologue of human and bovine Cβ2. Based on the present results and the existence of a human brain-specifically expressed Cβ splice variant designated Cβ4 that is identical to the former mouse Cβ2 splice variant, the mouse splice variant has now been renamed mouse Cβ4. Conclusion Murine lymphoid tissues express a protein that is a homologue of human and bovine Cβ2. The murine Cβ gene encodes the splice variants Cβ1, Cβ2, Cβ3 and Cβ4, as is the case with the human Cβ gene.

  13. Análise comparativa dos efeitos da base socioeconômica, dos tipos de crime e das condições de prisão na reincidência criminal Comparative analysis of the effects of socioeconomic status, crime type and prison conditions on criminal recidivism

    Directory of Open Access Journals (Sweden)

    Juan Mario Fandiño Mariño

    2002-12-01

    Full Text Available O objetivo central do trabalho é identificar e mensurar o poder explicativo relativo das seguintes três dimensões causais hipotéticas da reincidência criminal: a variáveis biográficas ou socioeconômicas, a saber: estado civil, filhos, naturalidade, idade, religião, raça, instrução formal e nível de qualificação da ocupação; b tipo de delito, segundo os seguintes oito tipos simplificados: homicídios, lesões corporais, roubos, furtos, estelionatos, posse e uso de entorpecentes e estupros; e c condições de prisão, incluindo a disponibilidade e qualificação dos funcionários - tanto de segurança quanto administrativos -, trabalho prisional dos apenados, treinamento profissionalizante e instrução em geral, espaços disponíveis e superlotação, e programas de assistência social ao apenado. O trabalho resume e avalia a literatura internacional relativa à reincidência criminal, tanto em termos metodológicos quanto teóricos, e apresenta um panorama histórico recente da criminalidade no estado do Rio Grande do Sul, como pano de fundo da análise da reincidência propriamente dita. Utilizando dados longitudinais oficiais das prisões para os anos de 1989 a 1997, e o cadastro geral oficial de apenados do estado, uma série de regressões é calculada pelo método step-wise, relacionando as três dimensões em questão com a variável reincidência, dicotomizada. A dimensão biográfica explica 32% da reincidência, o tipo de crime explica outros 9%, e as condições de prisão explicam ainda 16%, sugerindo uma ampla influência da política prisional na redução da reincidência.This work is primarily aimed at identifying and measuring the relative explicatory ability of the following three hypothetical causal dimensions of criminal recidivism: a socioeconomic variables, namely: marital status, children, place of birth, age, religion, race, educational level and qualification level of the occupation; b type of offense

  14. Genetic analysis of the cytoplasmic dynein subunit families.

    Directory of Open Access Journals (Sweden)

    K Kevin Pfister

    2006-01-01

    Full Text Available Cytoplasmic dyneins, the principal microtubule minus-end-directed motor proteins of the cell, are involved in many essential cellular processes. The major form of this enzyme is a complex of at least six protein subunits, and in mammals all but one of the subunits are encoded by at least two genes. Here we review current knowledge concerning the subunits, their interactions, and their functional roles as derived from biochemical and genetic analyses. We also carried out extensive database searches to look for new genes and to clarify anomalies in the databases. Our analysis documents evolutionary relationships among the dynein subunits of mammals and other model organisms, and sheds new light on the role of this diverse group of proteins, highlighting the existence of two cytoplasmic dynein complexes with distinct cellular roles.

  15. Ligand-induced formation of a transient tryptophan synthase complex with αββ subunit stoichiometry.

    Science.gov (United States)

    Ehrmann, Alexander; Richter, Klaus; Busch, Florian; Reimann, Julia; Albers, Sonja-Verena; Sterner, Reinhard

    2010-12-28

    The prototypical tryptophan synthases form a stable heterotetrameric αββα complex in which the constituting TrpA and TrpB1 subunits activate each other in a bidirectional manner. The hyperthermophilic archaeon Sulfolobus solfataricus does not contain a TrpB1 protein but instead two members of the phylogenetically distinct family of TrpB2 proteins, which are encoded within (sTrpB2i) and outside (sTrpB2a) the tryptophan operon. It has previously been shown that sTrpB2a does not functionally or structurally interact with sTrpA, whereas sTrpB2i substantially activates sTrpA in a unidirectional manner. However, in the absence of catalysis, no physical complex between sTrpB2i and sTrpA could be detected. In order to elucidate the structural requirements for complex formation, we have analyzed the interaction between sTrpA (α-monomer) and sTrpB2i (ββ-dimer) by means of spectroscopy, analytical gel filtration, and analytical ultracentrifugation, as well as isothermal titration calorimetry. In the presence of the TrpA ligand glycerol 3-phosphate (GP) and the TrpB substrate l-serine, sTrpA and sTrpB2i formed a physical complex with a thermodynamic dissociation constant of about 1 μM, indicating that the affinity between the α- and ββ-subunits is weaker by at least 1 order of magnitude than the affinity between the corresponding subunits of prototypical tryptophan synthases. The observed stoichiometry of the complex was 1 subunit of sTrpA per 2 subunits of sTrpB2i, which corresponds to a αββ quaternary structure and testifies to a strong negative cooperativity for the binding of the α-monomers to the ββ-dimer. The analysis of the interaction between sTrpB2i and sTrpA in the presence of several substrate, transition state, and product analogues suggests that the αββ complex remains stable during the whole catalytic cycle and disintegrates into α- and ββ-subunits upon the release of the reaction product tryptophan. The formation of a transient tryptophan

  16. Subunit Composition and Substrate Specificity of a MOF-containing Histone Acetyltransferase Distinct from the Male-specific Lethal (MSL) Complex*

    Science.gov (United States)

    Cai, Yong; Jin, Jingji; Swanson, Selene K.; Cole, Michael D.; Choi, Seung Hyuk; Florens, Laurence; Washburn, Michael P.; Conaway, Joan W.; Conaway, Ronald C.

    2010-01-01

    Human MOF (MYST1), a member of the MYST (Moz-Ybf2/Sas3-Sas2-Tip60) family of histone acetyltransferases (HATs), is the human ortholog of the Drosophila males absent on the first (MOF) protein. MOF is the catalytic subunit of the male-specific lethal (MSL) HAT complex, which plays a key role in dosage compensation in the fly and is responsible for a large fraction of histone H4 lysine 16 (H4K16) acetylation in vivo. MOF was recently reported to be a component of a second HAT complex, designated the non-specific lethal (NSL) complex (Mendjan, S., Taipale, M., Kind, J., Holz, H., Gebhardt, P., Schelder, M., Vermeulen, M., Buscaino, A., Duncan, K., Mueller, J., Wilm, M., Stunnenberg, H. G., Saumweber, H., and Akhtar, A. (2006) Mol. Cell 21, 811–823). Here we report an analysis of the subunit composition and substrate specificity of the NSL complex. Proteomic analyses of complexes purified through multiple candidate subunits reveal that NSL is composed of nine subunits. Two of its subunits, WD repeat domain 5 (WDR5) and host cell factor 1 (HCF1), are shared with members of the MLL/SET family of histone H3 lysine 4 (H3K4) methyltransferase complexes, and a third subunit, MCRS1, is shared with the human INO80 chromatin-remodeling complex. In addition, we show that assembly of the MOF HAT into MSL or NSL complexes controls its substrate specificity. Although MSL-associated MOF acetylates nucleosomal histone H4 almost exclusively on lysine 16, NSL-associated MOF exhibits a relaxed specificity and also acetylates nucleosomal histone H4 on lysines 5 and 8. PMID:20018852

  17. Properties of the subunits of wheat germ initiation factor 3.

    Science.gov (United States)

    Heufler, C; Browning, K S; Ravel, J M

    1988-11-10

    Wheat germ initiation factor 3 (eukaryotic initiation factor 3, eIF-3) contains ten non-identical subunits (p116, p107, p87, p83, p56, p45, p41, p36, p34 and p28). Monoclonal antibodies to all except two of the subunits (p41 and p28) were obtained. None of the monoclonal antibodies react with more than one subunit, and only monoclonal antibodies to p36 inhibit the ability of eIF-3 to support initiation of polypeptide synthesis. Two of the subunits (p116 and p107) are highly basic polypeptides (pI greater than or equal to 8); five (p87, p56, p45, p34 and p28) are acidic polypeptides (pI = 5.4-6.1); and three (p83, p41 and p36) appear to exist in more than one isoelectric form. Eight of the subunits of eIF-3 are iodinated rapidly in vitro; the highest incorporation is into p56 and the lowest incorporation is into p28. No incorporation into p41 or p28 is observed. When eIF-3 is treated with N-[3H]ethylmaleimide, approx. 30 alkyl groups per eIF-3 are incorporated, and the eIF-3 is inactivated. No incorporation into p83 or p28 is observed; incorporation of the alkyl groups into the other eight subunits occurs at different rates. The rate of inactivation of eIF-3 by N-ethylmaleimide is slower than the overall rate of incorporation of alkyl groups. eIF-3 is stable between pH 5.5 and 10. Below pH 5.5, eIF-3 is inactivated and precipitation of protein occurs. Partial dissociation of the subunits and inactivation of eIF-3 is obtained by treatment with 2 M urea. Attempts to reassociate the subunits into an active particle were unsuccessful.

  18. Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

    OpenAIRE

    Römling, Ute; Galperin, Michael Y

    2015-01-01

    Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis ...

  19. Acoustics of automotive catalytic converter assemblies

    Science.gov (United States)

    Dickey, Nolan S.; Selamet, Ahmet; Parks, Steve J.; Tallio, Kevin V.; Miazgowicz, Keith D.; Radavich, Paul M.

    2003-10-01

    In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the exhaust system acoustic behavior. A typical catalytic converter assembly employs a ceramic substrate to carry the catalytically active noble metals. The substrate has numerous parallel tubes and is mounted in a housing with swelling mat or wire mesh around its periphery. Seals at the ends of the substrate can be used to help force flow through the substrate and/or protect the mat material. Typically, catalytic converter studies only consider sound propagation in the small capillary tubes of the substrate. Investigations of the acoustic characteristics of entire catalytic converter assemblies (housing, substrate, seals, and mat) do not appear to be available. This work experimentally investigates the acoustic behavior of catalytic converter assemblies and the contributions of the separate components to sound attenuation. Experimental findings are interpreted with respect to available techniques for modeling sound propagation in ceramic substrates.

  20. Understanding catalytic biomass conversion through data mining

    NARCIS (Netherlands)

    E.J. Ras; B. McKay; G. Rothenberg

    2010-01-01

    Catalytic conversion of biomass is a key challenge that we chemists face in the twenty-first century. Worldwide, research is conducted into obtaining bulk chemicals, polymers and fuels. Our project centres on glucose valorisation via furfural derivatives using catalytic hydrogenation. We present her

  1. Silver nanocluster catalytic microreactors for water purification

    Science.gov (United States)

    Da Silva, B.; Habibi, M.; Ognier, S.; Schelcher, G.; Mostafavi-Amjad, J.; Khalesifard, H. R. M.; Tatoulian, M.; Bonn, D.

    2016-07-01

    A new method for the elaboration of a novel type of catalytic microsystem with a high specific area catalyst is developed. A silver nanocluster catalytic microreactor was elaborated by doping a soda-lime glass with a silver salt. By applying a high power laser beam to the glass, silver nanoclusters are obtained at one of the surfaces which were characterized by BET measurements and AFM. A microfluidic chip was obtained by sealing the silver coated glass with a NOA 81 microchannel. The catalytic activity of the silver nanoclusters was then tested for the efficiency of water purification by using catalytic ozonation to oxidize an organic pollutant. The silver nanoclusters were found to be very stable in the microreactor and efficiently oxidized the pollutant, in spite of the very short residence times in the microchannel. This opens the way to study catalytic reactions in microchannels without the need of introducing the catalyst as a powder or manufacturing complex packed bed microreactors.

  2. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Leppaelahti, J.; Koljonen, T. [VTT Energy, Espoo (Finland)

    1996-12-31

    In the combustion of fossil fuels, the principal source of nitrogen oxides is nitrogen bound in the fuel structure. In gasification, a large part of fuel nitrogen forms NH{sub 3}, which may form nitrogen oxides during gas combustion. If NH{sub 3} and other nitrogen species could be removed from hot gas, the NO emission could be considerably reduced. However, relatively little attention has been paid to finding new means of removing nitrogen compounds from the hot gasification gas. The possibility of selectively oxidizing NH{sub 3} to N{sub 2} in the hot gasification has been studied at VTT Energy. The largest NH{sub 3} reductions have been achieved by catalytic oxidation on aluminium oxides. (author) (4 refs.)

  3. Reducing catalytic converter pressure loss

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    This article examines why approximately 30--40% of total exhaust-system pressure loss occurs in the catalytic converter and what can be done to reduce pressure loss. High exhaust-system backpressure is of concern in the design of power trains for passenger cars and trucks because it penalizes fuel economy and limits peak power. Pressure losses occur due to fluid shear and turning during turbulent flow in the converter headers and in entry separation and developing laminar-flow boundary layers within the substrate flow passages. Some of the loss mechanisms are coupled. For example, losses in the inlet header are influenced by the presence of the flow resistance of a downstream substrate. Conversely, the flow maldistribution and pressure loss of the substrate(s) depend on the design of the inlet header.

  4. Non-catalytic recuperative reformer

    Energy Technology Data Exchange (ETDEWEB)

    Khinkis, Mark J.; Kozlov, Aleksandr P.; Kurek, Harry

    2015-12-22

    A non-catalytic recuperative reformer has a flue gas flow path for conducting hot flue gas from a thermal process and a reforming mixture flow path for conducting a reforming mixture. At least a portion of the reforming mixture flow path is embedded in the flue gas flow path to permit heat transfer from the hot flue gas to the reforming mixture. The reforming mixture flow path contains substantially no material commonly used as a catalyst for reforming hydrocarbon fuel (e.g., nickel oxide, platinum group elements or rhenium), but instead the reforming mixture is reformed into a higher calorific fuel via reactions due to the heat transfer and residence time. In a preferred embodiment, extended surfaces of metal material such as stainless steel or metal alloy that are high in nickel content are included within at least a portion of the reforming mixture flow path.

  5. Catalytic Graphitization of Phenolic Resin

    Institute of Scientific and Technical Information of China (English)

    Mu Zhao; Huaihe Song

    2011-01-01

    The catalytic graphitization of thermal plastic phenolic-formaldehyde resin with the aid of ferric nitrate (FN) was studied in detail. The morphologies and structural features of the products including onion-like carbon nanoparticles and bamboo-shaped carbon nanotubes were investigated by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy measurements. It was found that with the changes of loading content of FN and residence time at 1000℃, the products exhibited various morphologies. The TEM images showed that bamboo-shaped carbon nanotube consisted of tens of bamboo sticks and onion-like carbon nanoparticle was made up of quasi-spherically concentrically closed carbon nanocages.

  6. Rapamycin sensitivity of the Schizosaccharomyces pombe tor2 mutant and organization of two highly phosphorylated TOR complexes by specific and common subunits.

    Science.gov (United States)

    Hayashi, Takeshi; Hatanaka, Mitsuko; Nagao, Koji; Nakaseko, Yukinobu; Kanoh, Junko; Kokubu, Aya; Ebe, Masahiro; Yanagida, Mitsuhiro

    2007-12-01

    Nutrients are essential for cell growth and division. Screening of Schizosaccharomyces pombe temperature-sensitive strains led to the isolation of a nutrient-insensitive mutant, tor2-287. This mutant produces a nitrogen starvation-induced arrest phenotype in rich media, fails to recover from the arrest, and is hypersensitive to rapamycin. The L2048S substitution mutation in the catalytic domain in close proximity to the adenine base of ATP is unique as it is the sole known genetic cause of rapamycin hypersensitivity. Localization of Tor2 was speckled in the vegetative cytoplasm, and both speckled and membranous in the arrested cell cytoplasm. Using mass spectroscopic analysis, we identified six subunits (Tco89, Bit61, Toc1, Tel2, Tti1 and Cka1) that, in addition to the six previously identified subunits (Tor1, Tor2, Mip1/Raptor, Ste20/Rictor, Sin1/Avo1 and Wat1/Lst8), comprise the TOR complexes (TORCs). All of the subunits so far examined are multiply phosphorylated. Tel2 bound to Tti1 interacts with various phosphatidyl inositol kinase (PIK)-related kinases including Tra1, Tra2 and Rad3, as well as Tor1 and Tor2. Schizosaccharomyces pombe TORCs should thus be functionally redundant and might be broadly regulated through different subunits that are either common or specific to the two TORCs, or even common to various PIK-related kinases. Functional redundancy of the TORCs may explain the rapamycin hypersensitivity of tor2-287.

  7. Catalytic converter with thermoelectric generator

    Energy Technology Data Exchange (ETDEWEB)

    Parise, R.J.

    1998-07-01

    The unique design of an electrically heated catalyst (EHC) and the inclusion of an ECO valve in the exhaust of an internal combustion engine will meet the strict new emission requirements, especially at vehicle cold start, adopted by several states in this country as well as in Europe and Japan. The catalytic converter (CC) has been a most useful tool in pollution abatement for the automobile. But the emission requirements are becoming more stringent and, along with other improvements, the CC must be improved to meet these new standards. Coupled with the ECO valve, the EHC can meet these new emission limits. In an internal combustion engine vehicle (ICEV), approximately 80% of the energy consumed leaves the vehicle as waste heat: out the tail pipe, through the radiator, or convected/radiated off the engine. Included with the waste heat out the tail pipe are the products of combustion which must meet strict emission requirements. The design of a new CC is presented here. This is an automobile CC that has the capability of producing electrical power and reducing the quantity of emissions at vehicle cold start, the Thermoelectric Catalytic Power Generator. The CC utilizes the energy of the exothermic reactions that take place in the catalysis substrate to produce electrical energy with a thermoelectric generator. On vehicle cold start, the thermoelectric generator is used as a heat pump to heat the catalyst substrate to reduce the time to catalyst light-off. Thus an electrically heated catalyst (EHC) will be used to augment the abatement of tail pipe emissions. Included with the EHC in the exhaust stream of the automobile is the ECO valve. This valve restricts the flow of pollutants out the tail pipe of the vehicle for a specified amount of time until the EHC comes up to operating temperature. Then the ECO valve opens and allows the full exhaust, now treated by the EHC, to leave the vehicle.

  8. Identification of the uridine 5'-diphosphoglucose (UDP-Glc) binding subunit of cellulose synthase in Acetobacter xylinum using the photoaffinity probe 5-azido-UDP-Glc

    Energy Technology Data Exchange (ETDEWEB)

    Lin, F.C.; Brown, R.M. Jr.; Drake, R.R. Jr.; Haley, B.E. (Univ. of Texas, Austin (USA))

    1990-03-25

    Photoaffinity labeling of purified cellulose synthase with (beta-32P)5-azidouridine 5'-diphosphoglucose (UDP-Glc) has been used to identify the UDP-Glc binding subunit of the cellulose synthase from Acetobacter xylinum strain ATCC 53582. The results showed exclusive labeling of an 83-kDa polypeptide. Photoinsertion of (beta-32P)5-azido-UDP-Glc is stimulated by the cellulose synthase activator, bis-(3'----5') cyclic diguanylic acid. Addition of increasing amounts of UDP-Glc prevents photolabeling of the 83-kDa polypeptide. The reversible and photocatalyzed binding of this photoprobe also showed saturation kinetics. These studies demonstrate that the 83-kDa polypeptide is the catalytic subunit of the cellulose synthase in A. xylinum strain ATCC 53582.

  9. Identification of residues in the heme domain of soluble guanylyl cyclase that are important for basal and stimulated catalytic activity.

    Directory of Open Access Journals (Sweden)

    Padmamalini Baskaran

    Full Text Available Nitric oxide signals through activation of soluble guanylyl cyclase (sGC, a heme-containing heterodimer. NO binds to the heme domain located in the N-terminal part of the β subunit of sGC resulting in increased production of cGMP in the catalytic domain located at the C-terminal part of sGC. Little is known about the mechanism by which the NO signaling is propagated from the receptor domain (heme domain to the effector domain (catalytic domain, in particular events subsequent to the breakage of the bond between the heme iron and Histidine 105 (H105 of the β subunit. Our modeling of the heme-binding domain as well as previous homologous heme domain structures in different states point to two regions that could be critical for propagation of the NO activation signal. Structure-based mutational analysis of these regions revealed that residues T110 and R116 in the αF helix-β1 strand, and residues I41 and R40 in the αB-αC loop mediate propagation of activation between the heme domain and the catalytic domain. Biochemical analysis of these heme mutants allows refinement of the map of the residues that are critical for heme stability and propagation of the NO/YC-1 activation signal in sGC.

  10. Revolutionary systems for catalytic combustion and diesel catalytic particulate traps.

    Energy Technology Data Exchange (ETDEWEB)

    Stuecker, John Nicholas; Witze, Peter O.; Ferrizz, Robert Matthew; Cesarano, Joseph, III; Miller, James Edward

    2004-12-01

    This report is a summary of an LDRD project completed for the development of materials and structures conducive to advancing the state of the art for catalyst supports and diesel particulate traps. An ancillary development for bio-medical bone scaffolding was also realized. Traditionally, a low-pressure drop catalyst support, such as a ceramic honeycomb monolith, is used for catalytic reactions that require high flow rates of gases at high-temperatures. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. ''Robocasting'' is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low-pressure drops. These alternative 3-dimensional geometries may also provide a foundation for the development of self-regenerating supports capable of trapping and combusting soot particles from a diesel engine exhaust stream. This report describes the structures developed and characterizes the improved catalytic performance that can result. The results show that, relative to honeycomb monolith supports, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application. Practical applications include the combustion of natural gas for power generation, production of syngas, and hydrogen reforming reactions. The robocast lattice structures also show practicality for diesel particulate trapping. Preliminary results for trapping efficiency are reported as well as the development of electrically resistive lattices that can regenerate the structure

  11. Genetic Interactions among AMPK Catalytic Subunit Ssp2 and Glycogen Synthase Kinases Gsk3 and Gsk31 in Schizosaccharomyces Pombe.

    Science.gov (United States)

    Qingyun; Ma, Yan; Kato, Toshiaki; Furuyashiki, Tomoyuki

    2016-01-01

    In Schizosaccharomyces pombe, Ssp2, an ortholog of AMP-activated protein kinase (AMPK), is critical for cell growth at restrictive temperatures and under glucose depletion as well as sexual differentiation under nitrogen depletion. To identify genes genetically related to Ssp2, we performed a genetic screening to search for the genes whose overexpression rescued the growth defects in Δssp2 cells at restrictive temperatures, and identified 35 cosmids as multicopy suppressor genes. In Southern blot analyses, 22 out of these cosmids were hybridized to an ssp2+ probe. Using nucleotide sequencing, we identified the gsk3+ gene in one of the cosmids, and the remaining 12 cosmids were hybridized to a gsk3+ probe. Overexpression of the gsk3+ gene or the gsk31+ gene, another GSK3 member, rescues defective growth of Δssp2 cells at restrictive temperatures and under glucose depletion as well as sexual differentiation under nitrogen depletion. Δgsk3Δgsk31 double knockout cells, but neither Δgsk3 nor Δgsk31 single knockout cells, phenocopy Δssp2 cells. The deletion of the gsk3+ or gsk31+ gene augments the phenotypes of Δssp2 cells. These findings suggest that Gsk3 and Gsk31 are critical and interact with Ssp2 in multiple cellular functions. PMID:27604537

  12. Intranuclear Delivery of a Novel Antibody-Derived Radiosensitizer Targeting the DNA-Dependent Protein Kinase Catalytic Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Hairong [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); State Key Laboratory of Virology, Institute of Medical Virology, Wuhan University School of Medicine, Wuhan (China); Lee, Robert J. [Division of Pharmaceutics, College of Pharmacy, Ohio State University, Columbus, OH (United States); Haura, Eric B. [Thoracic Oncology and Experimental Therapeutics Programs, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL (United States); Edwards, John G. [Apeliotus Technologies, Inc., Atlanta, GA (United States); Dynan, William S. [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Li Shuyi, E-mail: sli@georgiahealth.edu [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Apeliotus Technologies, Inc., Atlanta, GA (United States)

    2012-07-01

    Purpose: To inhibit DNA double-strand break repair in tumor cells by delivery of a single-chain antibody variable region fragment (ScFv 18-2) to the cell nucleus. ScFv 18-2 binds to a regulatory region of the DNA-dependent protein kinase (DNA-PK), an essential enzyme in the nonhomologous end-joining pathway, and inhibits DNA end-joining in a cell-free system and when microinjected into single cells. Development as a radiosensitizer has been limited by the lack of a method for intranuclear delivery to target cells. We investigated a delivery method based on folate receptor-mediated endocytosis. Methods and Materials: A recombinant ScFv 18-2 derivative was conjugated to folate via a scissile disulfide linker. Folate-ScFv 18-2 was characterized for its ability to be internalized by tumor cells and to influence the behavior of ionizing radiation-induced repair foci. Radiosensitization was measured in a clonogenic survival assay. Survival curves were fitted to a linear-quadratic model, and between-group differences were evaluated by an F test. Sensitization ratios were determined based on mean inhibitory dose. Results: Human KB and NCI-H292 lung cancer cells treated with folate-conjugated ScFv 18-2 showed significant radiosensitization (p < 0.001). Sensitization enhancement ratios were 1.92 {+-} 0.42 for KB cells and 1.63 {+-} 0.13 for NCI-H292 cells. Studies suggest that treatment inhibits repair of radiation-induced DSBs, as evidenced by the persistence of {gamma}-H2AX-stained foci and by inhibition of staining with anti-DNA-PKcs phosphoserine 2056. Conclusions: Folate-mediated endocytosis is an effective method for intranuclear delivery of an antibody-derived DNA repair inhibitor.

  13. Disruption of the telomerase catalytic subunit gene from Arabidopsis inactivates telomerase and leads to a slow loss of telomeric DNA

    OpenAIRE

    Fitzgerald, Matthew S.; Riha, Karel; Gao, Feng; Ren, Shuxin; McKnight, Thomas D.; Shippen, Dorothy E.

    1999-01-01

    Telomerase is an essential enzyme that maintains telomeres on eukaryotic chromosomes. In mammals, telomerase is required for the lifelong proliferative capacity of normal regenerative and reproductive tissues and for sustained growth in a dedifferentiated state. Although the importance of telomeres was first elucidated in plants 60 years ago, little is known about the role of telomeres and telomerase in plant growth and development. Here we report the cloning and characterization of the Arabi...

  14. DNA-dependent protein kinase catalytic subunit inhibitor reverses acquired radioresistance in lung adenocarcinoma by suppressing DNA repair.

    Science.gov (United States)

    Li, Yong; Li, Hang; Peng, Wen; He, Xin-Yun; Huang, Min; Qiu, Dong; Xue, Ying-Bo; Lu, Liang

    2015-07-01

    The mechanisms underlying lung cancer radioresistance remain to be fully elucidated. The DNA repair pathway is a predominant target of radiotherapy, which is considered to be involved in the acquired radioresistance of cancer cells. The present study aimed to establish a radioresistant cell model using the A549 human lung cancer cell line, and to further investigate the potential mechanisms underlying the radioresistance. The A549R radioresistant lung cancer cell variant was established by exposing the parental A549 cells to repeated γ-ray irradiation at a total dose of 60 Gy. Colony formation assays were then used to determine cell survival following γ-ray exposure. The established radioresistant cells were subsequently treated with or without the NU7026 DNA-PKcs inhibitor. The levels of DNA damage were determined by counting the number of fluorescent γ-H2AX foci in the cells. The cellular capacity for DNA repair was assessed using antibodies for the detection of various DNA repair pathway proteins. The radioresistant sub-clones exhibited significantly decreased survival following NU7026 treatment, compared with the parental cells, as determined by colony formation assays (P<0.05), and this finding was found to be dose-dependent. Treatment with the DNA-dependent protein kinase (DNA-PK) inhibitor significantly reduced γ-H2AX foci formation (P<0.05) following acute radiation exposure in the radioresistant sub-clones, compared with the parental control cells. The decreased levels of γ-H2AX were accompanied by an increase in the percentage of apoptotic cells in the radioresistant cell line following post-radiation treatment with the DNA-PKcs inhibitor. The expression levels of proteins associated with the DNA repair pathway were altered markedly in the cells treated with NU7026. The results of the present study suggested that radioresistance may be associated with enhanced DNA repair following exposure to radiation, resulting in reduced apoptosis. Therefore, the quantity of γ-H2AX determines the radioresistance of cells. The DNA repair pathway is important in mediating radioresistance, and treatment with the DNA-PKcs inhibitor, NU7026 restored the acquired radiation resistance. PMID:25815686

  15. Expression of Mouse Telomerase Catalytic Subunit mTERT Gene in Testis of SD Rats and Its Significance

    Institute of Scientific and Technical Information of China (English)

    叶哲伟; 陈晓春; 杨述华; 陈江; 熊雅丽; 鲁功成

    2003-01-01

    To study the expression of mTERT gene in the testis of SD rats and its significance, insitu hybridization (ISH) techniques were used to detect the expression of telomerase gene mTERTmRNA in the testis of SD rats. The expression of mTERT was detectable in different-age male SDrats' testis. There was a positive correlation between the expression of mTERT and the location ofgerm cells (spermatogonia, spermatocyte, spermatid). In Sertoli cells, leydig cell and spermato-zoa, telomerase mTERT was not detected. Type A spermatogonia expressed the highest level of te-lomerase mTERT mRNA. Our results suggest that the expression of mTERT gene in the testis ofSD rats is of lifetime and coincide with the telomerase activity.

  16. Association between the PPP3CC gene, coding for the calcineurin gamma catalytic subunit, and bipolar disorder

    OpenAIRE

    Bellivier Frank; Chevalier Fabien; El Khoury Marie-Anne; Etain Bruno; Miot Stéphanie; Mathieu Flavie; Leboyer Marion; Giros Bruno; Tzavara Eleni T

    2008-01-01

    Abstract Background Calcineurin is a neuron-enriched phosphatase that regulates synaptic plasticity and neuronal adaptation. Activation of calcineurin, overall, antagonizes the effects of the cyclic AMP activated protein/kinase A. Thus, kinase/phosphatase dynamic balance seems to be critical for transition to long-term cellular responses in neurons, and disruption of this equilibrium should induce behavioral impairments in animal models. Genetic animal models, as well as post-mortem studies i...

  17. Intranuclear Delivery of a Novel Antibody-Derived Radiosensitizer Targeting the DNA-Dependent Protein Kinase Catalytic Subunit

    International Nuclear Information System (INIS)

    Purpose: To inhibit DNA double-strand break repair in tumor cells by delivery of a single-chain antibody variable region fragment (ScFv 18-2) to the cell nucleus. ScFv 18-2 binds to a regulatory region of the DNA-dependent protein kinase (DNA-PK), an essential enzyme in the nonhomologous end-joining pathway, and inhibits DNA end-joining in a cell-free system and when microinjected into single cells. Development as a radiosensitizer has been limited by the lack of a method for intranuclear delivery to target cells. We investigated a delivery method based on folate receptor–mediated endocytosis. Methods and Materials: A recombinant ScFv 18-2 derivative was conjugated to folate via a scissile disulfide linker. Folate-ScFv 18-2 was characterized for its ability to be internalized by tumor cells and to influence the behavior of ionizing radiation–induced repair foci. Radiosensitization was measured in a clonogenic survival assay. Survival curves were fitted to a linear-quadratic model, and between-group differences were evaluated by an F test. Sensitization ratios were determined based on mean inhibitory dose. Results: Human KB and NCI-H292 lung cancer cells treated with folate-conjugated ScFv 18-2 showed significant radiosensitization (p < 0.001). Sensitization enhancement ratios were 1.92 ± 0.42 for KB cells and 1.63 ± 0.13 for NCI-H292 cells. Studies suggest that treatment inhibits repair of radiation-induced DSBs, as evidenced by the persistence of γ-H2AX-stained foci and by inhibition of staining with anti-DNA-PKcs phosphoserine 2056. Conclusions: Folate-mediated endocytosis is an effective method for intranuclear delivery of an antibody-derived DNA repair inhibitor.

  18. AMPK-mediated AS160 phosphorylation in skeletal muscle is dependent on AMPK catalytic and regulatory subunits

    DEFF Research Database (Denmark)

    Treebak, Jonas Thue; Glund, Stephan; Deshmukh, Atul;

    2006-01-01

    AMP-activated protein kinase (AMPK) is a heterotrimeric protein that regulates glucose transport mediated by cellular stress or pharmacological agonists such as 5-aminoimidazole-4-carboxamide 1 ß-D-ribonucleoside (AICAR). AS160, a Rab GTPase-activating protein, provides a mechanism linking AMPK...... signaling (a2 AMPK knockout [KO], a2 AMPK kinase dead [KD], and ¿3 AMPK KO), AICAR effects on AS160 phosphorylation were severely blunted, highlighting that complexes containing a2 and ¿3 are necessary for AICAR-stimulated AS160 phosphorylation in intact skeletal muscle. Contraction-mediated AS160...

  19. Hypersecretion of the alpha-subunit in clinically non-functioning pituitary adenomas: Diagnostic accuracy is improved by adding alpha-subunit/gonadotropin ratio to levels of alpha-subunit

    DEFF Research Database (Denmark)

    Andersen, Marianne; Ganc-Petersen, Joanna; Jørgensen, Jens Otto Lunde;

    2010-01-01

    the reference intervals and decision limits for gonadotropin alpha-subunit, LH and FSH levels, and aratio (alpha-subunit/LH+FSH), especially taking into consideration patient gender and menstrual status. Furthermore, we wanted to examine if the diagnostic utility of alpha-subunit hypersecretion was improved...

  20. Genetic Construction of Truncated and Chimeric Metalloproteins Derived from the Alpha Subunit of Acetyl-CoA Synthase from Clostridium thermoaceticum

    Energy Technology Data Exchange (ETDEWEB)

    Huay-Keng Loke; Xiangshi Tan; Paul A. Lindahl

    2002-06-28

    In this study, a genetics-based method is used to truncate acetyl-coenzyme A synthase from Clostridium thermoaceticum (ACS), an alpha2beta2 tetrameric 310 kda bifunctional enzyme. ACS catalyzes the reversible reduction of CO2 to CO and the synthesis of acetyl-CoA from CO (or CO2 in the presence of low-potential reductants), CoA, and a methyl group bound to a corrinoid-iron sulfur protein (CoFeSP). ACS contains 7 metal-sulfur clusters of 4 different types called A, B, C, and D. The B, C, and D clusters are located in the 72 kda beta subunit while the A-cluster, a Ni-X-Fe4S4 cluster that serves as the active site for acetyl-CoA synthase activity, is located in the 82 kda alpha subunit. The extent to which the essential properties of the cluster, including catalytic, redox, spectroscopic, and substrate-binding properties, were retained as ACS was progressively truncated was determined. Acetyl-CoA synthase catalytic activity remained when the entire alpha subunit was removed, as long as CO, rather than CO2 and a low-potential reductant, was used as a substrate. Truncating an {approx} 30 kda region from the N-terminus of the alpha subunit yielded a 49 kda protein that lacked catalytic activity but exhibited A-cluster-like spectroscopic, redox, and CO binding properties. Further truncation afforded a 23 kda protein that lacked recognizable A-cluster properties except for UV-vis spectra typical of [Fe4S4]2+ clusters. Two chimeric proteins were constructed by fusing the gene encoding a ferredoxin from Chromatium vinosum to genes encoding the 49 kda and 82 kda fragments of the alpha subunit. The chimeric proteins exhibited EPR signals that were not the simple sum of the signals from the separate proteins, suggesting magnetic interactions between clusters. This study highlights the potential for using genetics to simplify the study of complex multi-centered metalloenzymes and to generate new complex metalloenzymes with interesting properties.

  1. Phosphorylation of ATPase subunits of the 26S proteasome.

    Science.gov (United States)

    Mason, G G; Murray, R Z; Pappin, D; Rivett, A J

    1998-07-01

    The 26S proteasome complex plays a major role in the non-lysosomal degradation of intracellular proteins. Purified 26S proteasomes give a pattern of more than 40 spots on 2D-PAGE gels. The positions of subunits have been identified by mass spectrometry of tryptic peptides and by immunoblotting with subunit-specific antipeptide antibodies. Two-dimensional polyacrylamide gel electrophoresis of proteasomes immunoprecipitated from [32P]phosphate-labelled human embryo lung L-132 cells revealed the presence of at least three major phosphorylated polypeptides among the regulatory subunits as well as the C8 and C9 components of the core 20S proteasome. Comparison with the positions of the regulatory polypeptides revealed a minor phosphorylated form to be S7 (MSS1). Antibodies against S4, S6 (TBP7) and S12 (MOV34) all cross-reacted at the position of major phosphorylated polypeptides suggesting that several of the ATPase subunits may be phosphorylated. The phosphorylation of S4 was confirmed by double immunoprecipitation experiments in which 26S proteasomes were immunoprecipitated as above and dissociated and then S4 was immunoprecipitated with subunit-specific antibodies. Antibodies against the non-ATPase subunit S10, which has been suggested by others to be phosphorylated, did not coincide with the position of a phosphorylated polypeptide. Some differences were observed in the 2D-PAGE pattern of proteasomes immunoprecipitated from cultured cells compared to purified rat liver 26S proteasomes suggesting possible differences in subunit compositions of 26S proteasomes.

  2. Pituitary glycoprotein hormone a-subunit secretion by cirrhotic patients

    Directory of Open Access Journals (Sweden)

    Oliveira M.C.

    1999-01-01

    Full Text Available Secretion of the a-subunit of pituitary glycoprotein hormones usually follows the secretion of intact gonadotropins and is increased in gonadal failure and decreased in isolated gonadotropin deficiency. The aim of the present study was to determine the levels of the a-subunit in the serum of patients with cirrhosis of the liver and to compare the results obtained for eugonadal cirrhotic patients with those obtained for cirrhotic patients with hypogonadotropic hypogonadism. Forty-seven of 63 patients with cirrhosis (74.6% presented hypogonadism (which was central in 45 cases and primary in 2, 7 were eugonadal, and 9 women were in normal menopause. The serum a-subunit was measured by the fluorimetric method using monoclonal antibodies. Cross-reactivity with LH, TSH, FSH and hCG was 6.5, 1.2, 4.3 and 1.1%, respectively, with an intra-assay coefficient of variation (CV of less than 5% and an interassay CV of 5%, and sensitivity limit of 4 ng/l. The serum a-subunit concentration ranged from 36 to 6253 ng/l, with a median of 273 ng/l. The median was 251 ng/l for patients with central hypogonadism and 198 ng/l for eugonadal patients. The correlation between the a-subunit and basal LH levels was significant both in the total sample (r = 0.48, P<0.01 and in the cirrhotic patients with central hypogonadism (r = 0.33, P = 0.02. Among men with central hypogonadism there was a negative correlation between a-subunit levels and total testosterone levels (r = 0.54, P<0.01 as well as free testosterone levels (r = -0.53, P<0.01. In conclusion, although the a-subunit levels are correlated with LH levels, at present they cannot be used as markers for hypogonadism in patients with cirrhosis of the liver.

  3. The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

    International Nuclear Information System (INIS)

    Highlights: → NDUFB6 is required for activity of mitochondrial complex I in human cell lines. → Lentivirus based RNA interference results in frequent off target insertions. → Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

  4. The NDUFB6 subunit of the mitochondrial respiratory chain complex I is required for electron transfer activity: A proof of principle study on stable and controlled RNA interference in human cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France); Rustin, Pierre, E-mail: pierre.rustin@inserm.fr [Inserm U676, Hopital Robert Debre, F-75019 Paris (France); Universite Paris 7, Faculte de medecine Denis Diderot, IFR02 Paris (France)

    2011-10-22

    Highlights: {yields} NDUFB6 is required for activity of mitochondrial complex I in human cell lines. {yields} Lentivirus based RNA interference results in frequent off target insertions. {yields} Flp-In recombinase mediated miRNA insertion allows gene-specific extinction. -- Abstract: Molecular bases of inherited deficiencies of mitochondrial respiratory chain complex I are still unknown in a high proportion of patients. Among 45 subunits making up this large complex, more than half has unknown function(s). Understanding the function of these subunits would contribute to our knowledge on mitochondrial physiology but might also reveal that some of these subunits are not required for the catalytic activity of the complex. A direct consequence of this finding would be the reduction of the number of candidate genes to be sequenced in patients with decreased complex I activity. In this study, we tested two different methods to stably extinct complex I subunits in cultured cells. We first found that lentivirus-mediated shRNA expression frequently resulted in the unpredicted extinction of additional gene(s) beside targeted ones. This can be ascribed to uncontrolled genetic material insertions in the genome of the host cell. This approach thus appeared inappropriate to study unknown functions of a gene. Next, we found it possible to specifically extinct a CI subunit gene by direct insertion of a miR targeting CI subunits in a Flp site (HEK293 Flp-In cells). By using this strategy we unambiguously demonstrated that the NDUFB6 subunit is required for complex I activity, and defined conditions suitable to undertake a systematic and stable extinction of the different supernumerary subunits in human cells.

  5. Development of Catalytic Cooking Plates

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin; Silversand, Fredrik [CATATOR AB, Lund (Sweden); Tena, Emmanuel; Berger, Marc [Gaz de France (France)

    2004-04-01

    Gas catalytic combustion for gas stoves or cooking plates (closed catalytic burner system with ceramic plates) is a very promising technique in terms of ease of cleaning, power modulation and emissions. Previous investigations show that wire mesh catalysts, prepared and supplied by Catator AB (CAT), seem to be very well suited for such applications. Beside significantly reducing the NOx-emissions, these catalysts offer important advantages such as good design flexibility, low pressure drop and high heat transfer capacity, where the latter leads to a quick thermal response. Prior to this project, Gaz de France (GdF) made a series of measurements with CAT's wire mesh catalysts in their gas cooking plates and compared the measured performance with similar results obtained with theirs cordierite monolith catalysts. Compared to the monolith catalyst, the wire mesh catalyst was found to enable very promising results with respect to both emission levels (<10 mg NO{sub x} /kWh, <5 mg CO/kWh) and life-time (>8000 h vs. 700 h at 200 kW/m{sup 2}). It was however established that the radiation and hence, the thermal efficiency of the cooking plate, was significantly less than is usually measured in combination with the monolith (15 % vs. 32 %). It was believed that the latter could be improved by developing new burner designs based on CAT's wire mesh concept. As a consequence, a collaboration project between GdF, CAT and the Swedish Gas Technology AB was created. This study reports on the design, the construction and the evaluation of new catalytic burners, based on CAT's wire mesh catalysts, used for the combustion of natural gas in gas cooking stoves. The evaluation of the burners was performed with respect to key factors such as thermal efficiency, emission quality and pressure drop, etc, by the use of theoretical simulations and experimental tests. Impacts of parameters such as the the wire mesh number, the wire mesh structure (planar or folded), the

  6. Catalytic reaction in confined flow channel

    Energy Technology Data Exchange (ETDEWEB)

    Van Hassel, Bart A.

    2016-03-29

    A chemical reactor comprises a flow channel, a source, and a destination. The flow channel is configured to house at least one catalytic reaction converting at least a portion of a first nanofluid entering the channel into a second nanofluid exiting the channel. The flow channel includes at least one turbulating flow channel element disposed axially along at least a portion of the flow channel. A plurality of catalytic nanoparticles is dispersed in the first nanofluid and configured to catalytically react the at least one first chemical reactant into the at least one second chemical reaction product in the flow channel.

  7. GABA receptor subunit composition relative to insecticide potency and selectivity.

    Science.gov (United States)

    Ratra, G S; Casida, J E

    2001-07-01

    Three observations on the 4-[(3)H]propyl-4'-ethynylbicycloorthobenzoate ([(3)H]EBOB) binding site in the gamma-aminobutyric acid (GABA) receptor indicate the specific target for insecticide action in human brain and a possible mechanism for selectivity. First, from published data, alpha-endosulfan, lindane and fipronil compete for the [(3)H]EBOB binding site with affinities of 0.3--7 nM in both human recombinant homooligomeric beta 3 receptors and housefly head membranes. Second, from structure-activity studies, including new data, GABAergic insecticide binding potency on the pentameric receptor formed from the beta 3 subunit correlates well with that on the housefly receptor (r=0.88, n=20). This conserved inhibitor specificity is consistent with known sequence homologies in the housefly GABA receptor and the human GABA(A) receptor beta 3 subunit. Third, as mostly new findings, various combinations of alpha 1, alpha 6, and gamma 2 subunits coexpressed with a beta 1 or beta 3 subunit confer differential insecticide binding sensitivity, particularly to fipronil, indicating that subunit composition is a major factor in insecticide selectivity.

  8. Role of adenosine 5'-monophosphate-activated protein kinase subunits in skeletal muscle mammalian target of rapamycin signaling

    DEFF Research Database (Denmark)

    Deshmukh, Atul S.; Treebak, Jonas Thue; Long, Yun Chau;

    2008-01-01

    AMP-activated protein kinase (AMPK) is an important energy-sensing protein in skeletal muscle. Mammalian target of rapamycin (mTOR) mediates translation initiation and protein synthesis through ribosomal S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). AMPK...... activation reduces muscle protein synthesis by down-regulating mTOR signaling, whereas insulin mediates mTOR signaling via Akt activation. We hypothesized that AMPK-mediated inhibitory effects on mTOR signaling depend on catalytic alpha2 and regulatory gamma3 subunits. Extensor digitorum longus muscle from...... AMPK alpha2 knockout (KO), AMPK gamma3 KO, and respective wild-type (WT) littermates (C57BL/6) were incubated in the presence of 5-aminoimidazole-4-carboxamide-1-beta-d-ribonucleoside (AICAR), insulin, or AICAR plus insulin. Phosphorylation of AMPK, Akt, and mTOR-associated signaling proteins were...

  9. Vacuum-insulated catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  10. Catalytic Chemistry on Oxide Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Asthagiri, Aravind; Dixon, David A.; Dohnalek, Zdenek; Kay, Bruce D.; Rodriquez, Jose A.; Rousseau, Roger J.; Stacchiola, Dario; Weaver, Jason F.

    2016-05-29

    Metal oxides represent one of the most important and widely employed materials in catalysis. Extreme variability of their chemistry provides a unique opportunity to tune their properties and to utilize them for the design of highly active and selective catalysts. For bulk oxides, this can be achieved by varying their stoichiometry, phase, exposed surface facets, defect, dopant densities and numerous other ways. Further, distinct properties from those of bulk oxides can be attained by restricting the oxide dimensionality and preparing them in the form of ultrathin films and nanoclusters as discussed throughout this book. In this chapter we focus on demonstrating such unique catalytic properties brought by the oxide nanoscaling. In the highlighted studies planar models are carefully designed to achieve minimal dispersion of structural motifs and to attain detailed mechanistic understanding of targeted chemical transformations. Detailed level of morphological and structural characterization necessary to achieve this goal is accomplished by employing both high-resolution imaging via scanning probe methods and ensemble-averaged surface sensitive spectroscopic methods. Three prototypical examples illustrating different properties of nanoscaled oxides in different classes of reactions are selected.

  11. Halogen Chemistry on Catalytic Surfaces.

    Science.gov (United States)

    Moser, Maximilian; Pérez-Ramírez, Javier

    2016-01-01

    Halogens are key building blocks for the manufacture of high-value products such as chemicals, plastics, and pharmaceuticals. The catalytic oxidation of HCl and HBr is an attractive route to recover chlorine and bromine in order to ensure the sustainability of the production processes. Very few materials withstand the high corrosiveness and the strong exothermicity of the reactions and among them RuO2 and CeO2-based catalysts have been successfully applied in HCl oxidation. The search for efficient systems for HBr oxidation was initiated by extrapolating the results of HCl oxidation based on the chemical similarity of these reactions. Interestingly, despite its inactivity in HCl oxidation, TiO2 was found to be an outstanding HBr oxidation catalyst, which highlighted that the latter reaction is more complex than previously assumed. Herein, we discuss the results of recent comparative studies of HCl and HBr oxidation on both rutile-type (RuO2, IrO2, and TiO2) and ceria-based catalysts using a combination of advanced experimental and theoretical methods to provide deeper molecular-level understanding of the reactions. This knowledge aids the design of the next-generation catalysts for halogen recycling. PMID:27131113

  12. The Crystal Structure of PF-8, the DNA Polymerase Accessory Subunit from Kaposi's Sarcoma-Associated Herpesvirus

    Energy Technology Data Exchange (ETDEWEB)

    Baltz, Jennifer L.; Filman, David J.; Ciustea, Mihai; Silverman, Janice Elaine Y.; Lautenschlager, Catherine L.; Coen, Donald M.; Ricciardi, Robert P.; Hogle, James M.; (UPENN)

    2009-12-01

    Kaposi's sarcoma-associated herpesvirus is an emerging pathogen whose mechanism of replication is poorly understood. PF-8, the presumed processivity factor of Kaposi's sarcoma-associated herpesvirus DNA polymerase, acts in combination with the catalytic subunit, Pol-8, to synthesize viral DNA. We have solved the crystal structure of residues 1 to 304 of PF-8 at a resolution of 2.8 {angstrom}. This structure reveals that each monomer of PF-8 shares a fold common to processivity factors. Like human cytomegalovirus UL44, PF-8 forms a head-to-head dimer in the form of a C clamp, with its concave face containing a number of basic residues that are predicted to be important for DNA binding. However, there are several differences with related proteins, especially in loops that extend from each monomer into the center of the C clamp and in the loops that connect the two subdomains of each protein, which may be important for determining PF-8's mode of binding to DNA and to Pol-8. Using the crystal structures of PF-8, the herpes simplex virus catalytic subunit, and RB69 bacteriophage DNA polymerase in complex with DNA and initial experiments testing the effects of inhibition of PF-8-stimulated DNA synthesis by peptides derived from Pol-8, we suggest a model for how PF-8 might form a ternary complex with Pol-8 and DNA. The structure and the model suggest interesting similarities and differences in how PF-8 functions relative to structurally similar proteins.

  13. Catalytic models developed through social work

    DEFF Research Database (Denmark)

    Jensen, Mogens

    2015-01-01

    The article develops the concept of catalytic processes in relation to social work with adolescents in an attempt to both reach a more nuanced understanding of social work and at the same time to develop the concept of catalytic processes in psychology. The social work is pedagogical treatment...... of adolescents placed in out-of-home care and is characterised using three situated cases as empirical data. Afterwards the concept of catalytic processes is briefly presented and then applied in an analysis of pedagogical treatment in the three cases. The result is a different conceptualisation of the social...... work with new possibilities of development of the work, but also suggestions for development of the concept of catalytic processes....

  14. Dengue vaccine: an update on recombinant subunit strategies.

    Science.gov (United States)

    Martin, J; Hermida, L

    2016-03-01

    Dengue is an increasing public health problem worldwide, with the four serotypes of the virus infecting over 390 million people annually. There is no specific treatment or antiviral drug for dengue, and prevention is largely limited to controlling the mosquito vectors or disrupting the human-vector contact. Despite the considerable progress made in recent years, an effective vaccine against the virus is not yet available. The development of a dengue vaccine has been hampered by many unique challenges, including the need to ensure the absence of vaccine-induced enhanced severity of disease. Recombinant protein subunit vaccines offer a safer alternative to other vaccine approaches. Several subunit vaccine candidates are presently under development, based on different structural and non-structural proteins of the virus. Novel adjuvants or immunopotentiating strategies are also being tested to improve their immunogenicity. This review summarizes the current status and development trends of subunit dengue vaccines. PMID:26982462

  15. Dengue vaccine: an update on recombinant subunit strategies.

    Science.gov (United States)

    Martin, J; Hermida, L

    2016-03-01

    Dengue is an increasing public health problem worldwide, with the four serotypes of the virus infecting over 390 million people annually. There is no specific treatment or antiviral drug for dengue, and prevention is largely limited to controlling the mosquito vectors or disrupting the human-vector contact. Despite the considerable progress made in recent years, an effective vaccine against the virus is not yet available. The development of a dengue vaccine has been hampered by many unique challenges, including the need to ensure the absence of vaccine-induced enhanced severity of disease. Recombinant protein subunit vaccines offer a safer alternative to other vaccine approaches. Several subunit vaccine candidates are presently under development, based on different structural and non-structural proteins of the virus. Novel adjuvants or immunopotentiating strategies are also being tested to improve their immunogenicity. This review summarizes the current status and development trends of subunit dengue vaccines.

  16. Cholera Toxin B: One Subunit with Many Pharmaceutical Applications

    Directory of Open Access Journals (Sweden)

    Keegan J. Baldauf

    2015-03-01

    Full Text Available Cholera, a waterborne acute diarrheal disease caused by Vibrio cholerae, remains prevalent in underdeveloped countries and is a serious health threat to those living in unsanitary conditions. The major virulence factor is cholera toxin (CT, which consists of two subunits: the A subunit (CTA and the B subunit (CTB. CTB is a 55 kD homopentameric, non-toxic protein binding to the GM1 ganglioside on mammalian cells with high affinity. Currently, recombinantly produced CTB is used as a component of an internationally licensed oral cholera vaccine, as the protein induces potent humoral immunity that can neutralize CT in the gut. Additionally, recent studies have revealed that CTB administration leads to the induction of anti-inflammatory mechanisms in vivo. This review will cover the potential of CTB as an immunomodulatory and anti-inflammatory agent. We will also summarize various recombinant expression systems available for recombinant CTB bioproduction.

  17. Testing experimental subunit furunculosis vaccines for rainbow trout

    DEFF Research Database (Denmark)

    Marana, Moonika H.; Chettri, Jiwan Kumar; Skov, Jakob;

    2016-01-01

    trout with subunit vaccines containing protein antigens that were selected based on an in silico antigen discovery approach. Thus, the proteome of AS strain A449 was analyzed by an antigen discovery platform and its proteins consequently ranked by their predicted ability to evoke protective immune...... AS 7 weeks post-vaccination by applying a novel, multi-puncture challenge method. The immune response in fish was evaluated following vaccination and challenge by measuring antibody levels and recording survival. The control group showed 56 % mortality whereas the groups of fish vaccinated...... with experimental subunit vaccines exhibited significantly lower mortalities (17-30 %). These results imply that in silico-predicted protective protein antigens of AS have significant protective properties and should be considered for further validation as potential candidates for a subunit vaccine against...

  18. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    Directory of Open Access Journals (Sweden)

    Vedi V.E.

    2012-12-01

    Full Text Available The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  19. MOBILE COMPLEX FOR CATALYTIC THERMAL WASTE TREATMENT

    OpenAIRE

    Vedi V.E.; Rovenskii A.I.

    2012-01-01

    The design and purpose of the basic units of the mobile waste processing complex “MPK” are described. Experimental data of catalytic purification of exhaust gases are presented. Experimental data on catalytic clearing of final gases of a designed mobile incinerator plant are shown. It is defined, that concentrating of parasitic bridging in waste gases of the complex are considerably smaller, rather than allowed by normative documents.

  20. Catalytic Radical Domino Reactions in Organic Synthesis

    Science.gov (United States)

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  1. Catalytic ammonia oxidation to nitrogen (I) oxide

    OpenAIRE

    MASALITINA NATALIYA YUREVNA; SAVENKOV ANATOLIY SERGEEVICH

    2015-01-01

    The process of synthesis of nitrous oxide by low-temperature catalytical oxidation of NH has been investigated for organic synthesis. The investigation has been carried out by the stage separation approach with NH oxidation occurring in several reaction zones, which characterized by different catalytic conditions. The selectivity for N₂O was 92–92,5 % at the ammonia conversion of 98–99.5 % in the optimal temperature range.

  2. Temperature Modulation of a Catalytic Gas Sensor

    OpenAIRE

    Eike Brauns; Eva Morsbach; Sebastian Kunz; Marcus Baeumer; Walter Lang

    2014-01-01

    The use of catalytic gas sensors usually offers low selectivity, only based on their different sensitivities for various gases due to their different heats of reaction. Furthermore, the identification of the gas present is not possible, which leads to possible misinterpretation of the sensor signals. The use of micro-machined catalytic gas sensors offers great advantages regarding the response time, which allows advanced analysis of the sensor response. By using temperature modulation, additi...

  3. Preparation and Catalytic Oxidation Activity on 2-mercaptoethanol of a Novel Catalytic Cellulose Fibres

    Institute of Scientific and Technical Information of China (English)

    YAO Yu-yuan; LI Ying-jie; CHEN Wen-xing; Lü Wang-yang; Lü Su-fang; XU Min-hong; LIU Fan

    2007-01-01

    Cobalt tetra(N-carbonylacylic) aminophthalocyanine was supported on cellulose fibres by graft reaction to obtain a novel polymer catalyst, catalytic cellulose fibres (CCF),and the optimal supporting conditions were pH = 6, 80℃,t = 120 min. The catalytic oxidation activity of CCF towards oxidation of 2-mereaptoethanol (MEA) in aqueous solution was investigated. The experimental results demonstrated that CCF had good catalytic oxidation activity on MEA at room temperature, causing no secondary pollution and remaining efficient for the repetitive tests with no obvious decrease of catalytic activity.

  4. Decreased catalytic activity and altered activation properties of PDE6C mutants associated with autosomal recessive achromatopsia

    DEFF Research Database (Denmark)

    Grau, Tanja; Artemyev, Nikolai O; Rosenberg, Thomas;

    2011-01-01

    Mutations in the gene encoding the catalytic subunit of the cone photoreceptor phosphodiesterase (PDE6C) have been recently reported in patients with autosomal recessive inherited achromatopsia (ACHM) and early-onset cone photoreceptor dysfunction. Here we present the results of a comprehensive...... characterization of six missense mutations applying the baculovirus system to express recombinant mutant and wildtype chimeric PDE6C/PDE5 proteins in Sf9 insect cells. Purified proteins were analyzed using Western blotting, phosphodiesterase (PDE) activity measurements as well as inhibition assays by zaprinast...

  5. Low efficiency deasphalting and catalytic cracking

    International Nuclear Information System (INIS)

    This patent describes a process for converting an asphaltene and metals containing heavy hydrocarbon feed to lighter, more valuable products the metals comprising Ni and V. It comprises: demetallizing the feed by deasphalting the feed in a solvent deasphalting means operating at solvent deasphalting conditions including a solvent: feed volume ratio of about 1:1 to 4:1, using a solvent selected from the group of C4 to 400 degrees F. hydrocarbons and mixtures thereof; recovering from the solvent rich fraction a demetallized oil intermediate product, having a boiling range and containing at least 10 wt.% of the asphaltenes, and 5 to 30% of the Ni and V, and at least 10 wt.% of the solvent present in the solvent rich phase produced in the deasphalting means; catalytically cracking the demetallized oil intermediate product in a catalytic cracking means operating at catalytic cracking conditions to produce a catalytically cracked product vapor fraction having a lower boiling range than the boiling range of the demetallized oil intermediate product; and fractionating the catalytically cracked product in a fractionation means to produce catalytically cracked product fractions

  6. Characterization of the putative tryptophan synthase β-subunit from Mycobacterium tuberculosis

    Institute of Scientific and Technical Information of China (English)

    Hongbo Shen; Yanping Yang; Feifei Wang; Ying Zhang; Naihao Ye; Shengfeng Xu; Honghai Wang

    2009-01-01

    The increasing emergence of drug-resistant tuberculosis (TB)poses a serious threat to the control of this disease.It is in urgent need to develop new TB drugs.Tryptophan biosynthetic pathway plays an important role in the growth and replication of Mycobacterium tuberculosis(Mtb).The β-subunit of tryptophan synthase(TrpB)catalyzes the last step of the tryptophan biosynthetic pathway,and it might be a potential target for TB drug design.In this study,we overexpressed,purified,and characterized the putative TrpB-encoding gene Rv1612 in Mtb H37Rv.Results showed that Mtb His-TrpB optimal enzymatic activity is at pH 7.8 with 0.15 M Na+or 0.18 M Mg2+ at 37℃.Structure analysis indicated that Mtb TrpB exhibited a typical β/α barrel structure.The amino acid residues believed to interact with the enzyme cofactor pyridoxal-5'-phosphate were predicted by homology modeling and structure alignment.The role of these residues in catalytic activity of the Mtb His-TrpB was confirmed by site-directed mutagenesis.These results provided reassuring structural information for drug design based on TrpB.

  7. Mitochondrial Genes of Dinoflagellates Are Transcribed by a Nuclear-Encoded Single-Subunit RNA Polymerase.

    Directory of Open Access Journals (Sweden)

    Chang Ying Teng

    Full Text Available Dinoflagellates are a large group of algae that contribute significantly to marine productivity and are essential photosynthetic symbionts of corals. Although these algae have fully-functioning mitochondria and chloroplasts, both their organelle genomes have been highly reduced and the genes fragmented and rearranged, with many aberrant transcripts. However, nothing is known about their RNA polymerases. We cloned and sequenced the gene for the nuclear-encoded mitochondrial polymerase (RpoTm of the dinoflagellate Heterocapsa triquetra and showed that the protein presequence targeted a GFP construct into yeast mitochondria. The gene belongs to a small gene family, which includes a variety of 3'-truncated copies that may have originated by retroposition. The catalytic C-terminal domain of the protein shares nine conserved sequence blocks with other single-subunit polymerases and is predicted to have the same fold as the human enzyme. However, the N-terminal (promoter binding/transcription initiation domain is not well-conserved. In conjunction with the degenerate nature of the mitochondrial genome, this suggests a requirement for novel accessory factors to ensure the accurate production of functional mRNAs.

  8. Functional mapping of the fission yeast DNA polymerase δ B-subunit Cdc1 by site-directed and random pentapeptide insertion mutagenesis

    Directory of Open Access Journals (Sweden)

    Gray Fiona C

    2009-08-01

    Full Text Available Abstract Background DNA polymerase δ plays an essential role in chromosomal DNA replication in eukaryotic cells, being responsible for synthesising the bulk of the lagging strand. In fission yeast, Pol δ is a heterotetrameric enzyme comprising four evolutionarily well-conserved proteins: the catalytic subunit Pol3 and three smaller subunits Cdc1, Cdc27 and Cdm1. Pol3 binds directly to the B-subunit, Cdc1, which in turn binds the C-subunit, Cdc27. Human Pol δ comprises the same four subunits, and the crystal structure was recently reported of a complex of human p50 and the N-terminal domain of p66, the human orthologues of Cdc1 and Cdc27, respectively. Results To gain insights into the structure and function of Cdc1, random and directed mutagenesis techniques were used to create a collection of thirty alleles encoding mutant Cdc1 proteins. Each allele was tested for function in fission yeast and for binding of the altered protein to Pol3 and Cdc27 using the two-hybrid system. Additionally, the locations of the amino acid changes in each protein were mapped onto the three-dimensional structure of human p50. The results obtained from these studies identify amino acid residues and regions within the Cdc1 protein that are essential for interaction with Pol3 and Cdc27 and for in vivo function. Mutations specifically defective in Pol3-Cdc1 interactions allow the identification of a possible Pol3 binding surface on Cdc1. Conclusion In the absence of a three-dimensional structure of the entire Pol δ complex, the results of this study highlight regions in Cdc1 that are vital for protein function in vivo and provide valuable clues to possible protein-protein interaction surfaces on the Cdc1 protein that will be important targets for further study.

  9. Regulation of Aerobic Energy Metabolism in Podospora anserina by Two Paralogous Genes Encoding Structurally Different c-Subunits of ATP Synthase

    Science.gov (United States)

    Sellem, Carole H.; di Rago, Jean-Paul; Lasserre, Jean-Paul; Ackerman, Sharon H.; Sainsard-Chanet, Annie

    2016-01-01

    Most of the ATP in living cells is produced by an F-type ATP synthase. This enzyme uses the energy of a transmembrane electrochemical proton gradient to synthesize ATP from ADP and inorganic phosphate. Proton movements across the membrane domain (FO) of the ATP synthase drive the rotation of a ring of 8–15 c-subunits, which induces conformational changes in the catalytic part (F1) of the enzyme that ultimately promote ATP synthesis. Two paralogous nuclear genes, called Atp9-5 and Atp9-7, encode structurally different c-subunits in the filamentous fungus Podospora anserina. We have in this study identified differences in the expression pattern for the two genes that correlate with the mitotic activity of cells in vegetative mycelia: Atp9-7 is transcriptionally active in non-proliferating (stationary) cells while Atp9-5 is expressed in the cells at the extremity (apex) of filaments that divide and are responsible for mycelium growth. When active, the Atp9-5 gene sustains a much higher rate of c-subunit synthesis than Atp9-7. We further show that the ATP9-7 and ATP9-5 proteins have antagonist effects on the longevity of P. anserina. Finally, we provide evidence that the ATP9-5 protein sustains a higher rate of mitochondrial ATP synthesis and yield in ATP molecules per electron transferred to oxygen than the c-subunit encoded by Atp9-7. These findings reveal that the c-subunit genes play a key role in the modulation of ATP synthase production and activity along the life cycle of P. anserina. Such a degree of sophistication for regulating aerobic energy metabolism has not been described before. PMID:27442014

  10. Catalytic hydrogenation of carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Wayland, B.B.

    1992-12-01

    This project is focused on developing strategies to accomplish the reduction and hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. Our approaches to this issue are based on the recognition that rhodium macrocycles have unusually favorable thermodynamic values for producing a series of intermediate implicated in the catalytic hydrogenation of CO. Observations of metalloformyl complexes produced by reactions of H{sub 2} and CO, and reductive coupling of CO to form metallo {alpha}-diketone species have suggested a multiplicity of routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in constructing energy profiles for a variety of potential pathways, and these schemes are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. Variation of the electronic and steric effects associated with the ligand arrays along with the influences of the reaction medium provide the chemical tools for tuning these factors. Emerging knowledge of the factors that contribute to M-H, M-C and M-O bond enthalpies is directing the search for ligand arrays that will expand the range of metal species that have favorable thermodynamic parameters to produce the primary intermediates for CO hydrogenation. Studies of rhodium complexes are being extended to non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics. Multifunctional catalyst systems designed to couple the ability of rhodium complexes to produce formyl and diketone intermediates with a second catalyst that hydrogenates these imtermediates are promising approaches to accomplish CO hydrogenation at mild conditions.

  11. Efficient reconstitution of functional Escherichia coli 30S ribosomal subunits from a complete set of recombinant small subunit ribosomal proteins.

    Science.gov (United States)

    Culver, G M; Noller, H F

    1999-06-01

    Previous studies have shown that the 30S ribosomal subunit of Escherichia coli can be reconstituted in vitro from individually purified ribosomal proteins and 16S ribosomal RNA, which were isolated from natural 30S subunits. We have developed a 30S subunit reconstitution system that uses only recombinant ribosomal protein components. The genes encoding E. coli ribosomal proteins S2-S21 were cloned, and all twenty of the individual proteins were overexpressed and purified. Reconstitution, following standard procedures, using the complete set of recombinant proteins and purified 16S ribosomal RNA is highly inefficient. Efficient reconstitution of 30S subunits using these components requires sequential addition of proteins, following either the 30S subunit assembly map (Mizushima & Nomura, 1970, Nature 226:1214-1218; Held et al., 1974, J Biol Chem 249:3103-3111) or following the order of protein assembly predicted from in vitro assembly kinetics (Powers et al., 1993, J MoI Biol 232:362-374). In the first procedure, the proteins were divided into three groups, Group I (S4, S7, S8, S15, S17, and S20), Group II (S5, S6, S9, Sll, S12, S13, S16, S18, and S19), and Group III (S2, S3, S10, S14, and S21), which were sequentially added to 16S rRNA with a 20 min incubation at 42 degrees C following the addition of each group. In the second procedure, the proteins were divided into Group I (S4, S6, S11, S15, S16, S17, S18, and S20), Group II (S7, S8, S9, S13, and S19), Group II' (S5 and S12) and Group III (S2, S3, S10, S14, and S21). Similarly efficient reconstitution is observed whether the proteins are grouped according to the assembly map or according to the results of in vitro 30S subunit assembly kinetics. Although reconstitution of 30S subunits using the recombinant proteins is slightly less efficient than reconstitution using a mixture of total proteins isolated from 30S subunits, it is much more efficient than reconstitution using proteins that were individually isolated

  12. The origin of the supernumerary subunits and assembly factors of complex I: A treasure trove of pathway evolution.

    Science.gov (United States)

    Elurbe, Dei M; Huynen, Martijn A

    2016-07-01

    We review and document the evolutionary origin of all complex I assembly factors and nine supernumerary subunits from protein families. Based on experimental data and the conservation of critical residues we identify a spectrum of protein function conservation between the complex I representatives and their non-complex I homologs. This spectrum ranges from proteins that have retained their molecular function but in which the substrate specificity may have changed or have become more specific, like NDUFAF5, to proteins that have lost their original molecular function and critical catalytic residues like NDUFAF6. In between are proteins that have retained their molecular function, which however appears unrelated to complex I, like ACAD9, or proteins in which amino acids of the active site are conserved but for which no enzymatic activity has been reported, like NDUFA10. We interpret complex I evolution against the background of molecular evolution theory. Complex I supernumerary subunits and assembly factors appear to have been recruited from proteins that are mitochondrial and/or that are expressed when complex I is active. Within the evolution of complex I and its assembly there are many cases of neofunctionalization after gene duplication, like ACAD9 and TMEM126B, one case of subfunctionalization: ACPM1 and ACPM2 in Yarrowia lipolytica, and one case in which a complex I protein itself appears to have been the source of a new protein from another complex: NDUFS6 gave rise to cytochrome c oxidase subunit COX4/COX5b. Complex I and its assembly can therewith be regarded as a treasure trove for pathway evolution. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:27048931

  13. Assembly of the Arp5 (Actin-related Protein) Subunit Involved in Distinct INO80 Chromatin Remodeling Activities.

    Science.gov (United States)

    Yao, Wei; Beckwith, Sean L; Zheng, Tina; Young, Thomas; Dinh, Van T; Ranjan, Anand; Morrison, Ashby J

    2015-10-16

    ATP-dependent chromatin remodeling, which repositions and restructures nucleosomes, is essential to all DNA-templated processes. The INO80 chromatin remodeling complex is an evolutionarily conserved complex involved in diverse cellular processes, including transcription, DNA repair, and replication. The functional diversity of the INO80 complex can, in part, be attributed to specialized activities of distinct subunits that compose the complex. Furthermore, structural analyses have identified biochemically discrete subunit modules that assemble along the Ino80 ATPase scaffold. Of particular interest is the Saccharomyces cerevisiae Arp5-Ies6 module located proximal to the Ino80 ATPase and the Rvb1-Rvb2 helicase module needed for INO80-mediated in vitro activity. In this study we demonstrate that the previously uncharacterized Ies2 subunit is required for Arp5-Ies6 association with the catalytic components of the INO80 complex. In addition, Arp5-Ies6 module assembly with the INO80 complex is dependent on distinct conserved domains within Arp5, Ies6, and Ino80, including the spacer region within the Ino80 ATPase domain. Arp5-Ies6 interacts with chromatin via assembly with the INO80 complex, as IES2 and INO80 deletion results in loss of Arp5-Ies6 chromatin association. Interestingly, ectopic addition of the wild-type Arp5-Ies6 module stimulates INO80-mediated ATP hydrolysis and nucleosome sliding in vitro. However, the addition of mutant Arp5 lacking unique insertion domains facilitates ATP hydrolysis in the absence of nucleosome sliding. Collectively, these results define the requirements of Arp5-Ies6 assembly, which are needed to couple ATP hydrolysis to productive nucleosome movement.

  14. On the Structural Context and Identification of Enzyme Catalytic Residues

    OpenAIRE

    Yu-Tung Chien; Shao-Wei Huang

    2013-01-01

    Enzymes play important roles in most of the biological processes. Although only a small fraction of residues are directly involved in catalytic reactions, these catalytic residues are the most crucial parts in enzymes. The study of the fundamental and unique features of catalytic residues benefits the understanding of enzyme functions and catalytic mechanisms. In this work, we analyze the structural context of catalytic residues based on theoretical and experimental structure flexibility. The...

  15. CMF70 is a subunit of the dynein regulatory complex.

    Science.gov (United States)

    Kabututu, Zakayi P; Thayer, Michelle; Melehani, Jason H; Hill, Kent L

    2010-10-15

    Flagellar motility drives propulsion of several important pathogens and is essential for human development and physiology. Motility of the eukaryotic flagellum requires coordinate regulation of thousands of dynein motors arrayed along the axoneme, but the proteins underlying dynein regulation are largely unknown. The dynein regulatory complex, DRC, is recognized as a focal point of axonemal dynein regulation, but only a single DRC subunit, trypanin/PF2, is currently known. The component of motile flagella 70 protein, CMF70, is broadly and uniquely conserved among organisms with motile flagella, suggesting a role in axonemal motility. Here we demonstrate that CMF70 is part of the DRC from Trypanosoma brucei. CMF70 is located along the flagellum, co-sediments with trypanin in sucrose gradients and co-immunoprecipitates with trypanin. RNAi knockdown of CMF70 causes motility defects in a wild-type background and suppresses flagellar paralysis in cells with central pair defects, thus meeting the functional definition of a DRC subunit. Trypanin and CMF70 are mutually conserved in at least five of six extant eukaryotic clades, indicating that the DRC was probably present in the last common eukaryotic ancestor. We have identified only the second known subunit of this ubiquitous dynein regulatory system, highlighting the utility of combined genomic and functional analyses for identifying novel subunits of axonemal sub-complexes. PMID:20876659

  16. The Essential Anatomical Subunit Approximation Unilateral Cleft Lip Repair.

    Science.gov (United States)

    Chong, David K; Swanson, Jordan W

    2016-07-01

    The anatomical subunit approximation cleft lip repair advantageously achieves a balanced lip contour, with the line of repair hidden along seams of aesthetic subunits. Dr. David Fisher's original description of the repair reflects the considerable thought that went into the evolution of his design. As his technique has gained acceptance in the intervening 10 years, the authors note several key principles embodied in it that represent a shift in the cleft lip repair paradigm. The authors believe understanding these principles is important to mastery of the anatomical subunit technique, and facilitate its teaching. First, design a plan that adheres to anatomical subunits and perform measurements precisely. Second, identify and adequately release each cleft tissue layer from the lip and nose to enable restoration of balance. Third, drive surgical approximation through inset of the lateral muscle into the superiorly backcut medial orbicularis muscle, followed by skin closure with inferior triangle interposition above the white roll. In this article, the authors present essential components of the technique, and identify several principles that enable its successful execution. PMID:27348690

  17. Partial agonists and subunit selectivity at NMDA receptors

    DEFF Research Database (Denmark)

    Risgaard, Rune; Hansen, Kasper Bø; Clausen, Rasmus Prætorius

    2010-01-01

    Subunit-selective ligands for glutamate receptors remains an area of interest as glutamate is the major excitatory neurotransmitter in the brain and involved in a number of diseased states in the central nervous system (CNS). Few subtype-selective ligands are known, especially among the N-methyl-...

  18. Emergence of ion channel modal gating from independent subunit kinetics.

    Science.gov (United States)

    Bicknell, Brendan A; Goodhill, Geoffrey J

    2016-09-01

    Many ion channels exhibit a slow stochastic switching between distinct modes of gating activity. This feature of channel behavior has pronounced implications for the dynamics of ionic currents and the signaling pathways that they regulate. A canonical example is the inositol 1,4,5-trisphosphate receptor (IP3R) channel, whose regulation of intracellular Ca(2+) concentration is essential for numerous cellular processes. However, the underlying biophysical mechanisms that give rise to modal gating in this and most other channels remain unknown. Although ion channels are composed of protein subunits, previous mathematical models of modal gating are coarse grained at the level of whole-channel states, limiting further dialogue between theory and experiment. Here we propose an origin for modal gating, by modeling the kinetics of ligand binding and conformational change in the IP3R at the subunit level. We find good agreement with experimental data over a wide range of ligand concentrations, accounting for equilibrium channel properties, transient responses to changing ligand conditions, and modal gating statistics. We show how this can be understood within a simple analytical framework and confirm our results with stochastic simulations. The model assumes that channel subunits are independent, demonstrating that cooperative binding or concerted conformational changes are not required for modal gating. Moreover, the model embodies a generally applicable principle: If a timescale separation exists in the kinetics of individual subunits, then modal gating can arise as an emergent property of channel behavior. PMID:27551100

  19. Editing modifies the GABA(A) receptor subunit alpha3

    DEFF Research Database (Denmark)

    Ohlson, Johan; Pedersen, Jakob Skou; Haussler, David;

    2007-01-01

    to find selectively edited sites and combined it with bioinformatic techniques that find stem-loop structures suitable for editing. We present here the first verified editing candidate detected by this screening procedure. We show that Gabra-3, which codes for the alpha3 subunit of the GABA...

  20. Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

    Science.gov (United States)

    Römling, Ute; Galperin, Michael Y.

    2015-01-01

    Summary Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host. PMID:26077867

  1. Thermostable Subunit Vaccines for Pulmonary Delivery: How Close Are We?

    DEFF Research Database (Denmark)

    Foged, Camilla

    2016-01-01

    , such as influenza, tuberculosis, and Ebola, for which no good universal vaccines exist. At least two pharmaceutical improvements are expected to help filling this gap: i) The development of thermostable vaccine dosage forms, and ii) the full exploitation of the adjuvant technology for subunit vaccines to potentiate...

  2. Catalytic coal liquefaction. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Weller, S W

    1981-01-01

    Monolith catalysts of MoO/sub 3/-CoO-Al/sub 2/O/sub 3/ were prepared and tested for coal liquefaction in a stirred autoclave. In general, the monolith catalysts were not as good as particulate catalysts prepared on Corning alumina supports. Measurement of O/sub 2/ chemisorption and BET surface area has been made on a series of Co/Mo/Al/sub 2/O/sub 3/ catalysts obtained from PETC. The catalysts were derived from Cyanamid 1442A and had been tested for coal liquefaction in batch autoclaves and continuous flow units. MoO/sub 3/-Al/sub 2/O/sub 3/ catalysts over the loading range 3.9 to 14.9 wt % MoO/sub 3/ have been studied with respect to BET surface (before and after reduction), O/sub 2/ chemisorption at -78/sup 0/C, redox behavior at 500/sup 0/C, and activity for cyclohexane dehydrogenation at 500/sup 0/C. In connection with the fate of tin catalysts during coal liquefaction, calculations have been made of the relative thermodynamic stability of SnCl/sub 2/, Sn, SnO/sub 2/, and SnS in the presence of H/sub 2/, HCl, H/sub 2/S and H/sub 2/O. Ferrous sulfate dispersed in methylnaphthalene has been shown to be reduced to ferrous sulfide under typical coal hydroliquefaction conditions (1 hour, 450/sup 0/C, 1000 psi initial p/sub H/sub 2//). This suggests that ferrous sulfide may be the common catalytic ingredient when either (a) ferrous sulfate impregnated on powdered coal, or (b) finely divided iron pyrite is used as the catalyst. Old research on impregnated ferrous sulfate, impregnated ferrous halides, and pyrite is consistent with this assumption. Eight Co/Mo/Al/sub 2/O/sub 3/ catalysts from commercial suppliers, along with SnCl/sub 2/, have been studied for the hydrotreating of 1-methylnaphthalene (1-MN) in a stirred autoclave at 450 and 500/sup 0/C.

  3. Directed mutagenesis of the strongly conserved aspartate 242 in the beta-subunit of Escherichia coli proton-ATPase.

    Science.gov (United States)

    Al-Shawi, M K; Parsonage, D; Senior, A E

    1988-12-25

    Oligonucleotide-directed mutagenesis was used to substitute Asn or Val for residue Asp-242 in the beta-subunit of Escherichia coli F1-ATPase. Asp-242 is strongly conserved in beta-subunits of F1-ATPase enzymes, in a region of sequence which shows homology with numerous nucleotide-binding proteins. By analogy with adenylate kinase (Fry, D.C., Kuby, S.A., and Mildvan, A.S. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 907-911), beta-Asp-242 of F1-ATPase might participate in catalysis through electrostatic effects on the substrate Mg2+ or through hydrogen bonding to the substrate(s); an acid-base catalytic role is also plausible. The substitutions Asn and Val were chosen to affect the charge, hydrogen-bonding ability, and hydrophobicity of residue beta-Asp-242. Both mutations significantly impaired oxidative phosphorylation rates in vivo and membrane ATPase and ATP-driven proton-pumping activities in vitro. Asn-242 was more detrimental than Val-242. Purified soluble mutant F1-ATPases had normal molecular size and subunit composition, and displayed 7% (beta-Asn-242) and 17% (beta-Val-242) of normal specific Mg-ATPase activity. The relative MgATPase activities of both mutant enzymes showed similar pH dependence to normal. Relative MgATPase and CaATPase activities of normal and mutant enzymes were compared at widely varied pMg and pCa. The mutations had little effect on KM MgATP, but KM CaATP was reduced. The data showed that the carboxyl side-chain of beta-Asp-242 is not involved in catalysis either as a general acid-base catalyst or through direct involvement in any protonation/deprotonation-linked mechanism, nor is it likely to be directly involved in liganding to substrate Mg2+ during the reaction. Specificity constants (kcat/KM) for MgATP and CaATP were reduced in both mutant enzymes, showing that the mutations destabilized interactions between the catalytic nucleotide-binding domain and the transition state.

  4. Isolation and characterization of recombinant human casein kinase II subunits alpha and beta from bacteria

    DEFF Research Database (Denmark)

    Grankowski, N; Boldyreff, B; Issinger, O G

    1991-01-01

    cDNA encoding the casein kinase II (CKII) subunits alpha and beta of human origin were expressed in Escherichia coli using expression vector pT7-7. Significant expression was obtained with E. coli BL21(DE3). The CKII subunits accounted for approximately 30% of the bacterial protein; however, most...... determined for the subunits of the native enzyme. The recombinant alpha subunit exhibited protein kinase activity which was greatest in the absence of monovalent ions. With increasing amounts of salt, alpha subunit kinase activity declined rapidly. Addition of the beta subunit led to maximum stimulation...

  5. Molecular dynamics and mutational analysis of the catalytic and translocation cycle of RNA polymerase

    Directory of Open Access Journals (Sweden)

    Kireeva Maria L

    2012-06-01

    Full Text Available Abstract Background During elongation, multi-subunit RNA polymerases (RNAPs cycle between phosphodiester bond formation and nucleic acid translocation. In the conformation associated with catalysis, the mobile “trigger loop” of the catalytic subunit closes on the nucleoside triphosphate (NTP substrate. Closing of the trigger loop is expected to exclude water from the active site, and dehydration may contribute to catalysis and fidelity. In the absence of a NTP substrate in the active site, the trigger loop opens, which may enable translocation. Another notable structural element of the RNAP catalytic center is the “bridge helix” that separates the active site from downstream DNA. The bridge helix may participate in translocation by bending against the RNA/DNA hybrid to induce RNAP forward movement and to vacate the active site for the next NTP loading. The transition between catalytic and translocation conformations of RNAP is not evident from static crystallographic snapshots in which macromolecular motions may be restrained by crystal packing. Results All atom molecular dynamics simulations of Thermus thermophilus (Tt RNAP reveal flexible hinges, located within the two helices at the base of the trigger loop, and two glycine hinges clustered near the N-terminal end of the bridge helix. As simulation progresses, these hinges adopt distinct conformations in the closed and open trigger loop structures. A number of residues (described as “switch” residues trade atomic contacts (ion pairs or hydrogen bonds in response to changes in hinge orientation. In vivo phenotypes and in vitro activities rendered by mutations in the hinge and switch residues in Saccharomyces cerevisiae (Sc RNAP II support the importance of conformational changes predicted from simulations in catalysis and translocation. During simulation, the elongation complex with an open trigger loop spontaneously translocates forward relative to the elongation complex with a

  6. A novel liquid system of catalytic hydrogenation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis that endothermic aqueous-phase reforming of oxygenated hydrocarbons for H2 production and exothermic liquid phase hydrogenation of organic compounds are carried out under extremely close conditions of temperature and pressure over the same type of catalyst, a novel liquid system of catalytic hydrogenation has been proposed, in which hydrogen produced from aqueous-phase reforming of oxygenated hydrocarbons is in situ used for liquid phase hydrogenation of organic compounds. The usage of active hydrogen generated from aqueous-phase reforming of oxygenated hydrocarbons for liquid catalytic hydrogenation of organic compounds could lead to increasing the selectivity to H2 in the aqueous-phase reforming due to the prompt removal of hydrogen on the active centers of the catalyst. Meanwhile, this novel liquid system of catalytic hydrogenation might be a potential method to improve the selectivity to the desired product in liquid phase catalytic hydrogenation of organic compounds. On the other hand, for this novel liquid system of catalytic hydrogenation, some special facilities for H2 generation, storage and transportation in traditional liquid phase hydrogenation industry process are yet not needed. Thus, it would simplify the working process of liquid phase hydrogenation and increase the energy usage and hydrogen productivity.

  7. Effect of high and low molecular weight glutenin subunits, and subunits of gliadin on physicochemical parameters of different wheat genotypes

    Directory of Open Access Journals (Sweden)

    Mariana Souza Costa

    2013-02-01

    Full Text Available Identification of functional properties of wheat flour by specific tests allows genotypes with appropriate characteristics to be selected for specific industrial uses. The objective of wheat breeding programs is to improve the quality of germplasm bank in order to be able to develop wheat with suitable gluten strength and extensibility for bread making. The aim of this study was to evaluate 16 wheat genotypes by correlating both glutenin subunits of high and low molecular weight and gliadin subunits with the physicochemical characteristics of the grain. Protein content, sedimentation volume, sedimentation index, and falling number values were analyzed after the grains were milled. Hectoliter weight and mass of 1000 seeds were also determined. The glutenin and gliadin subunits were separated using polyacrylamide gel in the presence of sodium dodecyl sulfate. The data were evaluated using variance analysis, Pearson's correlation, principal component analysis, and cluster analysis. The IPR 85, IPR Catuara TM, T 091015, and T 091069 genotypes stood out from the others, which indicate their possibly superior grain quality with higher sedimentation volume, higher sedimentation index, and higher mass of 1000 seeds; these genotypes possessed the subunits 1 (Glu-A1, 5 + 10 (Glu-D1, c (Glu-A3, and b (Glu-B3, with exception of T 091069 genotype that possessed the g allele instead of b in the Glu-B3.

  8. [Isolation and catalytic properties of the soluble monomeric form of inorganic pyrophosphatase from baker's yeast].

    Science.gov (United States)

    Kasho, V N; Bakuleva, N P; Baĭkov, A A; Avaeva, S M

    1982-06-01

    Data from sedimentation analysis suggest that modification of about 40% of free amino groups of inorganic pyrophosphatase by maleic anhydride, pH 10.5, results in a loss of the enzyme ability to form dimers at neutral values of pH. The specific activity of monomeric pyrophosphatase is 50-80% of that of the dimeric form. The monomer has a pH optimum of about 7, requires metal ions for activation of both enzyme and substrate and is capable of exergonic synthesis of PPi in the active center. The enzyme binding to PPi is strongly stabilized by fluoride. The experimental data indicate that the individual subunit of inorganic pyrophosphatase possesses all the main catalytic properties of native dimeric molecule. PMID:6126223

  9. Hydrostatic pressure induces conformational and catalytic changes on two alcohol dehydrogenases but no oligomeric dissociation.

    Science.gov (United States)

    Dallet, S; Legoy, M D

    1996-05-01

    A comparison between the pressure effects on the catalysis of Thermoanaerobium brockii alcohol dehydrogenase (TBADH: a thermostable tetrameric enzyme) and yeast alcohol dehydrogenase (YADH: a mesostable tetrameric enzyme) revealed a different behaviour. YADH activity is continuously inhibited by an increase of pressure, whereas YADH affinity seems less sensitive to pressure. TBADH activity is enhanced by pressure up to 100 MPa. TBADH affinity for alcoholic substrates increases if pressure increases, was TBADH affinity for NADP decreases when pressure increases. Hypothesis has been raised concerning the dissociation of oligomeric enzymes under high hydrostatic pressure ( YADH at all pressures and TBADH for pressures above 100 MPa is not correlated to subunit dissociation. Hence we suggest that enzymes under pressure encounter a molecular rearrangement which can either have a positive or a negative effect on activity. Finally, we have observed that the catalytic behaviour of alcohol dehydrogenases under pressure is connected to their thermostability.

  10. Catalytic nanoarchitectonics for environmentally compatible energy generation

    Directory of Open Access Journals (Sweden)

    Hideki Abe

    2016-01-01

    Full Text Available Environmentally compatible energy management is one of the biggest challenges of the 21st century. Low-temperature conversion of chemical to electrical energy is of particular importance to minimize the impact to the environment while sustaining the consumptive economy. In this review, we shed light on one of the most versatile energy-conversion technologies: heterogeneous catalysts. We establish the integrity of structural tailoring in heterogeneous catalysts at different scales in the context of an emerging paradigm in materials science: catalytic nanoarchitectonics. Fundamental backgrounds of energy-conversion catalysis are first provided together with a perspective through state-of-the-art energy-conversion catalysis including catalytic exhaust remediation, fuel-cell electrocatalysis and photosynthesis of solar fuels. Finally, the future evolution of catalytic nanoarchitectonics is overviewed: possible combinations of heterogeneous catalysts, organic molecules and even enzymes to realize reaction-selective, highly efficient and long-life energy conversion technologies which will meet the challenge we face.

  11. ADAR proteins: structure and catalytic mechanism.

    Science.gov (United States)

    Goodman, Rena A; Macbeth, Mark R; Beal, Peter A

    2012-01-01

    Since the discovery of the adenosine deaminase (ADA) acting on RNA (ADAR) family of proteins in 1988 (Bass and Weintraub, Cell 55:1089-1098, 1988) (Wagner et al. Proc Natl Acad Sci U S A 86:2647-2651, 1989), we have learned much about their structure and catalytic mechanism. However, much about these enzymes is still unknown, particularly regarding the selective recognition and processing of specific adenosines within substrate RNAs. While a crystal structure of the catalytic domain of human ADAR2 has been solved, we still lack structural data for an ADAR catalytic domain bound to RNA, and we lack any structural data for other ADARs. However, by analyzing the structural data that is available along with similarities to other deaminases, mutagenesis and other biochemical experiments, we have been able to advance the understanding of how these fascinating enzymes function. PMID:21769729

  12. Catalytic Organic Transformations Mediated by Actinide Complexes

    Directory of Open Access Journals (Sweden)

    Isabell S. R. Karmel

    2015-10-01

    Full Text Available This review article presents the development of organoactinides and actinide coordination complexes as catalysts for homogeneous organic transformations. This chapter introduces the basic principles of actinide catalysis and deals with the historic development of actinide complexes in catalytic processes. The application of organoactinides in homogeneous catalysis is exemplified in the hydroelementation reactions, such as the hydroamination, hydrosilylation, hydroalkoxylation and hydrothiolation of alkynes. Additionally, the use of actinide coordination complexes for the catalytic polymerization of α-olefins and the ring opening polymerization of cyclic esters is presented. The last part of this review article highlights novel catalytic transformations mediated by actinide compounds and gives an outlook to the further potential of this field.

  13. Highly Dense Isolated Metal Atom Catalytic Sites

    DEFF Research Database (Denmark)

    Chen, Yaxin; Kasama, Takeshi; Huang, Zhiwei;

    2015-01-01

    -ray diffraction. A combination of electron microscopy images with X-ray absorption spectra demonstrated that the silver atoms were anchored on five-fold oxygen-terminated cavities on the surface of the support to form highly dense isolated metal active sites, leading to excellent reactivity in catalytic oxidation......Atomically dispersed noble-metal catalysts with highly dense active sites are promising materials with which to maximise metal efficiency and to enhance catalytic performance; however, their fabrication remains challenging because metal atoms are prone to sintering, especially at a high metal...... loading. A dynamic process of formation of isolated metal atom catalytic sites on the surface of the support, which was achieved starting from silver nanoparticles by using a thermal surface-mediated diffusion method, was observed directly by using in situ electron microscopy and in situ synchrotron X...

  14. Reactivity of organic compounds in catalytic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Minachev, Kh.M.; Bragin, O.V.

    1978-01-01

    A comprehensive review of 1976 Soviet research on catalysis delivered to the 1977 annual session of the USSR Academy of Science Council on Catalysis (Baku 6/16-20/77) covers hydrocarbon reactions, including hydrogenation and hydrogenolysis, dehydrogenation, olefin dimerization and disproportionation, and cyclization and dehydrocyclization (e.g., piperylene cyclization and ethylene cyclotrimerization); catalytic and physicochemical properties of zeolites, including cracking, dehydrogenation, and hydroisomerization catalytic syntheses and conversion of heterocyclic and functional hydrocarbon derivatives, including partial and total oxidation (e.g., of o-xylene to phthalic anhydride); syntheses of thiophenes from alkanes and hydrogen sulfide over certain dehydrogenation catalysts; catalytic syntheses involving carbon oxides ( e.g., the development of a new heterogeneous catalyst for hydroformylation of olefins), and of Co-MgO zeolitic catalysts for synthesis of aliphatic hydrocarbons from carbon dioxide and hydrogen, and fabrication of high-viscosity lubricating oils over bifunctional aluminosilicate catalysts.

  15. Catalytic microreactors for portable power generation

    Energy Technology Data Exchange (ETDEWEB)

    Karagiannidis, Symeon [Paul Scherer Institute, Villigen (Switzerland)

    2011-07-01

    ''Catalytic Microreactors for Portable Power Generation'' addresses a problem of high relevance and increased complexity in energy technology. This thesis outlines an investigation into catalytic and gas-phase combustion characteristics in channel-flow, platinum-coated microreactors. The emphasis of the study is on microreactor/microturbine concepts for portable power generation and the fuels of interest are methane and propane. The author carefully describes numerical and experimental techniques, providing a new insight into the complex interactions between chemical kinetics and molecular transport processes, as well as giving the first detailed report of hetero-/homogeneous chemical reaction mechanisms for catalytic propane combustion. The outcome of this work will be widely applied to the industrial design of micro- and mesoscale combustors. (orig.)

  16. Use catalytic combustion for LHV gases

    Energy Technology Data Exchange (ETDEWEB)

    Tucci, E.R.

    1982-03-01

    This paper shows how low heating value (LHV) waste gases can be combusted to recover energy even when the gases won't burn in a normal manner. Significant energy and economic savings can result by adopting this process. Catalytic combustion is a heterogeneous surface-catalyzed air oxidation of fuel, gaseous or liquid, to generate thermal energy in a flameless mode. The catalytic combustion process is quite complex since it involves numerous catalytic surface and gas-phase chemical reactions. During low temperature surface-catalyzed combustion, as in start-up, the combustion stage is under kinetically controlled conditions. The discussion covers the following topics - combustor substrates; combustor washcoating and catalyzing; combustor operational modes (turbine or tabular modes); applications in coal gasification and in-situ gasification; waste process gases. 16 refs.

  17. Xylan-Degrading Catalytic Flagellar Nanorods.

    Science.gov (United States)

    Klein, Ágnes; Szabó, Veronika; Kovács, Mátyás; Patkó, Dániel; Tóth, Balázs; Vonderviszt, Ferenc

    2015-09-01

    Flagellin, the main component of flagellar filaments, is a protein possessing polymerization ability. In this work, a novel fusion construct of xylanase A from B. subtilis and Salmonella flagellin was created which is applicable to build xylan-degrading catalytic nanorods of high stability. The FliC-XynA chimera when overexpressed in a flagellin deficient Salmonella host strain was secreted into the culture medium by the flagellum-specific export machinery allowing easy purification. Filamentous assemblies displaying high surface density of catalytic sites were produced by ammonium sulfate-induced polymerization. FliC-XynA nanorods were resistant to proteolytic degradation and preserved their enzymatic activity for a long period of time. Furnishing enzymes with self-assembling ability to build catalytic nanorods offers a promising alternative approach to enzyme immobilization onto nanostructured synthetic scaffolds. PMID:25966869

  18. Electro Catalytic Oxidation (ECO) Operation

    Energy Technology Data Exchange (ETDEWEB)

    Morgan Jones

    2011-03-31

    The power industry in the United States is faced with meeting many new regulations to reduce a number of air pollutants including sulfur dioxide, nitrogen oxides, fine particulate matter, and mercury. With over 1,000 power plants in the US, this is a daunting task. In some cases, traditional pollution control technologies such as wet scrubbers and SCRs are not feasible. Powerspan's Electro-Catalytic Oxidation, or ECO{reg_sign} process combines four pollution control devices into a single integrated system that can be installed after a power plant's particulate control device. Besides achieving major reductions in emissions of sulfur dioxide (SO{sub 2}), nitrogen oxides (NOx), fine particulate matter (PM2.5) and mercury (Hg), ECO produces a highly marketable fertilizer, which can help offset the operating costs of the process system. Powerspan has been operating a 50-MW ECO commercial demonstration unit (CDU) at FirstEnergy Corp.'s R.E. Burger Plant near Shadyside, Ohio, since February 2004. In addition to the CDU, a test loop has been constructed beside the CDU to demonstrate higher NOx removal rates and test various scrubber packing types and wet ESP configurations. Furthermore, Powerspan has developed the ECO{reg_sign}{sub 2} technology, a regenerative process that uses a proprietary solvent to capture CO{sub 2} from flue gas. The CO{sub 2} capture takes place after the capture of NOx, SO{sub 2}, mercury, and fine particulate matter. Once the CO{sub 2} is captured, the proprietary solution is regenerated to release CO{sub 2} in a form that is ready for geological storage or beneficial use. Pilot scale testing of ECO{sub 2} began in early 2009 at FirstEnergy's Burger Plant. The ECO{sub 2} pilot unit is designed to process a 1-MW flue gas stream and produce 20 tons of CO{sub 2} per day, achieving a 90% CO{sub 2} capture rate. The ECO{sub 2} pilot program provided the opportunity to confirm process design and cost estimates, and prepare for large

  19. Cytosolic phospholipase A2: a member of the signalling pathway of a new G protein α subunit in Sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    González-Méndez Ricardo

    2009-05-01

    Full Text Available Abstract Background Sporothrix schenckii is a pathogenic dimorphic fungus, the etiological agent of sporotrichosis, a lymphocutaneous disease that can remain localized or can disseminate, involving joints, lungs, and the central nervous system. Pathogenic fungi use signal transduction pathways to rapidly adapt to changing environmental conditions and S. schenckii is no exception. S. schenckii yeast cells, either proliferate (yeast cell cycle or engage in a developmental program that includes proliferation accompanied by morphogenesis (yeast to mycelium transition depending on the environmental conditions. The principal intracellular receptors of environmental signals are the heterotrimeric G proteins, suggesting their involvement in fungal dimorphism and pathogenicity. Identifying these G proteins in fungi and their involvement in protein-protein interactions will help determine their role in signal transduction pathways. Results In this work we describe a new G protein α subunit gene in S. schenckii, ssg-2. The cDNA sequence of ssg-2 revealed a predicted open reading frame of 1,065 nucleotides encoding a 355 amino acids protein with a molecular weight of 40.9 kDa. When used as bait in a yeast two-hybrid assay, a cytoplasmic phospholipase A2 catalytic subunit was identified as interacting with SSG-2. The sspla2 gene, revealed an open reading frame of 2538 bp and encoded an 846 amino acid protein with a calculated molecular weight of 92.62 kDa. The principal features that characterize cPLA2 were identified in this enzyme such as a phospholipase catalytic domain and the characteristic invariable arginine and serine residues. A role for SSPLA2 in the control of dimorphism in S. schenckii is suggested by observing the effects of inhibitors of the enzyme on the yeast cell cycle and the yeast to mycelium transition in this fungus. Phospholipase A2 inhibitors such as AACOCF3 (an analogue of archidonic acid and isotetrandrine (an inhibitor of G protein

  20. Mutational analysis of a ras catalytic domain

    DEFF Research Database (Denmark)

    Willumsen, B M; Papageorge, A G; Kung, H F;

    1986-01-01

    We used linker insertion-deletion mutagenesis to study the catalytic domain of the Harvey murine sarcoma virus v-rasH transforming protein, which is closely related to the cellular rasH protein. The mutants displayed a wide range of in vitro biological activity, from those that induced focal...... transformation of NIH 3T3 cells with approximately the same efficiency as the wild-type v-rasH gene to those that failed to induce any detectable morphologic changes. Correlation of transforming activity with the location of the mutations enabled us to identify three nonoverlapping segments within the catalytic...

  1. Thermal and catalytic pyrolysis of plastic waste

    Directory of Open Access Journals (Sweden)

    Débora Almeida

    2016-02-01

    Full Text Available Abstract The amount of plastic waste is growing every year and with that comes an environmental concern regarding this problem. Pyrolysis as a tertiary recycling process is presented as a solution. Pyrolysis can be thermal or catalytical and can be performed under different experimental conditions. These conditions affect the type and amount of product obtained. With the pyrolysis process, products can be obtained with high added value, such as fuel oils and feedstock for new products. Zeolites can be used as catalysts in catalytic pyrolysis and influence the final products obtained.

  2. A catalytic surface for amyloid fibril formation

    Energy Technology Data Exchange (ETDEWEB)

    Hammarstroem, P; Ali, M M; Mishra, R; Tengvall, P; Lundstroem, I [Department of Physics, Biology and Chemistry, Linkoeping University, SE-581 83 Linkoeping (Sweden); Svensson, S [Astra Zeneca R and D, SE-151 85 Soedertaelje (Sweden)], E-mail: ingemar@ifm.liu.se

    2008-03-15

    A hydrophobic surface incubated in a solution of protein molecules (insulin monomers) was made into a catalytic surface for amyloid fibril formation by repeatedly incubate, rinse and dry the surface. The present contribution describes how this unexpected transformation occurred and its relation to rapid fibrillation of insulin solutions in contact with the surface. A tentative model of the properties of the catalytic surface is given, corroborated by ellipsometric measurements of the thickness of the organic layer on the surface and by atomic force microscopy. The surfaces used were spontaneously oxidized silicon made hydrophobic through treatment in dichlorodimethylsilane.

  3. Catalytic gasification of oil-shales

    Energy Technology Data Exchange (ETDEWEB)

    Lapidus, A.; Avakyan, T. [I.M. Gubkin Russian State Univ. of Oil and Gas, Moscow (Russian Federation); Strizhakova, Yu. [Samara State Univ. (Russian Federation)

    2012-07-01

    Nowadays, the problem of complex usage of solid fossil fuels as raw materials for obtaining of motor fuels and chemical products is becoming increasingly important. A one of possible solutions of the problem is their gasification with further processing of gaseous and liquid products. In this work we have investigated the process of thermal and catalytic gasification of Baltic and Kashpir oil-shales. We have shown that, as compared with non-catalytic process, using of nickel catalyst in the reaction increases the yield of gas, as well as hydrogen content in it, and decreases the amount of liquid products. (orig.)

  4. Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.

  5. Subunit topology in the V type ATPase and related enzymes

    NARCIS (Netherlands)

    Chaban, Yuriy

    2005-01-01

    During the last decades impressive progress has been made in understanding of the catalytic mechanism of F-type ATP synthase, which is the key enzyme in the energy metabolism of eukaryotes and most bacteria. This enzyme catalyzes the final step in the process of oxidative phosphorylation in bacteria

  6. Bigenomic transcriptional regulation of all thirteen cytochrome c oxidase subunit genes by specificity protein 1

    OpenAIRE

    Dhar, Shilpa S.; Johar, Kaid; Wong-Riley, Margaret T. T.

    2013-01-01

    Cytochrome c oxidase (COX) is one of only four known bigenomic proteins, with three mitochondria-encoded subunits and 10 nucleus-encoded ones derived from nine different chromosomes. The mechanism of regulating this multi-subunit, bigenomic enzyme is not fully understood. We hypothesize that specificity protein 1 (Sp1) functionally regulates the 10 nucleus-encoded COX subunit genes directly and the three mitochondrial COX subunit genes indirectly by regulating mitochondrial transcription fact...

  7. Regulation of expression of a soybean storage protein subunit gene. Progress report

    International Nuclear Information System (INIS)

    We have found that the methionine repression of the β-subunit gene expression is not due to degradation of the β-subunit but is due to an effect on synthesis of the β-subunit. The effect of methionine on the synthesis of the β-is due to an inhibition of β-subunit mRNA synthesis. 3 references, 1 figure

  8. Arrangement of subunits and domains within the Octopus dofleini hemocyanin molecule.

    OpenAIRE

    Miller, K I; Schabtach, E; van Holde, K E

    1990-01-01

    Native Octopus dofleini hemocyanin appears as a hollow cylinder in the electron microscope. It is composed of 10 polypeptide subunits, each folded into seven globular oxygen-binding domains. The native structure reassociates spontaneously from subunits in the presence of Mg2+ ions. We have selectively removed the C-terminal domain and purified the resulting six-domain subunits. Although these six-domain subunits do not associate efficiently at pH 7.2, they undergo nearly complete reassociatio...

  9. Developments of Subunit and VLP Vaccines Against Influenza A Virus

    Institute of Scientific and Technical Information of China (English)

    Ma-ping Deng; Zhi-hong Hu; Hua-lin Wang; Fei Deng

    2012-01-01

    Influenza virus is a continuous and severe global threat to mankind.The continuously re-emerging disease gives rise to thousands of deaths and enormous economic losses each year,which emphasizes the urgency and necessity to develop high-quality influenza vaccines in a safer,more efficient and economic way.The influenza subunit and VLP vaccines,taking the advantage of recombinant DNA technologies and expression system platforms,can be produced in such an ideal way.This review summarized the recent advancements in the research and development of influenza subunit and VLP vaccines based on the recombinant expression of hemagglutinin antigen (HA),neuraminidase antigen (NA),Matrix 2 protein (M2) and nucleocapsid protein (NP).It would help to get insight into the current stage of influenza vaccines,and suggest the future design and development of novel influenza vaccines.

  10. Mapping of the Mouse Actin Capping Protein Beta Subunit Gene

    Directory of Open Access Journals (Sweden)

    Cooper John A

    2000-07-01

    Full Text Available Abstract Background Capping protein (CP, a heterodimer of α and β subunits, is found in all eukaryotes. CP binds to the barbed ends of actin filaments in vitro and controls actin assembly and cell motility in vivo. Vertebrates have three isoforms of CPβ produced by alternatively splicing from one gene; lower organisms have one gene and one isoform. Results We isolated genomic clones corresponding to the β subunit of mouse CP and identified its chromosomal location by interspecies backcross mapping. Conclusions The CPβ gene (Cappb1 mapped to Chromosome 4 between Cdc42 and D4Mit312. Three mouse mutations, snubnose, curly tail, and cribriform degeneration, map in the vicinity of the β gene.

  11. Ire1 Has Distinct Catalytic Mechanisms for XBP1/HAC1 Splicing and RIDD

    Directory of Open Access Journals (Sweden)

    Arvin B. Tam

    2014-11-01

    Full Text Available An evolutionarily conserved unfolded protein response (UPR component, IRE1, cleaves XBP1/HAC1 introns in order to generate spliced mRNAs that are translated into potent transcription factors. IRE1 also cleaves endoplasmic-reticulum-associated RNAs leading to their decay, an activity termed regulated IRE1-dependent decay (RIDD; however, the mechanism by which IRE1 differentiates intron cleavage from RIDD is not well understood. Using in vitro experiments, we found that IRE1 has two different modes of action: XBP1/HAC1 is cleaved by IRE1 subunits acting cooperatively within IRE1 oligomers, whereas a single subunit of IRE1 performs RIDD without cooperativity. Furthermore, these distinct activities can be separated by complementation of catalytically inactive IRE1 RNase and mutations at oligomerization interfaces. Using an IRE1 RNase inhibitor, STF-083010, selective inhibition of XBP1 splicing indicates that XBP1 promotes cell survival, whereas RIDD leads to cell death, revealing modulation of IRE1 activities as a drug-development strategy.

  12. GABAB(1) receptor subunit isoforms differentially regulate stress resilience

    OpenAIRE

    O’Leary, Olivia F.; Felice, Daniela; Galimberti, Stefano; Savignac, Hélène M.; Bravo, Javier A.; Crowley, Tadhg; El Yacoubi, Malika; Vaugeois, Jean-Marie; Gassmann, Martin; Bettler, Bernhard; Dinan, Timothy G.; Cryan, John F.

    2014-01-01

    Stress can increase susceptibility to developing psychiatric disorders, including depression. Understanding the neurobiological mechanisms underlying stress resilience and susceptibility is key to identifying novel targets for the development of more effective treatments for stress-related psychiatric disorders. Here we show that specific isoforms of GABAB receptor subunits differentially regulate stress resilience. Specifically, GABAB(1a)−/− mice are more susceptible whereas GABAB(1b)−/− mic...

  13. Characterisation of connective tissue cells containing factor XIII subunit a.

    OpenAIRE

    Adány, R; Glukhova, M A; Kabakov, A Y; Muszbek, L

    1988-01-01

    Paraffin embedded sections of human liver, lymph node, and placenta showed that certain connective tissue cells were positive for factor XIII subunit a. These cells were further characterised by double immunofluorescence labelling and by combined immunofluorescence and enzyme cytochemical staining on frozen sections. They were labelled by the monoclonal antibodies RFD7 and anti-Leu M3 (markers of the macrophage cell line) but gave a negative reaction for the fibroblast marker IIG10 and showed...

  14. Molybdenum cofactor properties and [Fe-S] cluster coordination in Escherichia coli nitrate reductase A: investigation by site-directed mutagenesis of the conserved his-50 residue in the NarG subunit.

    Science.gov (United States)

    Magalon, A; Asso, M; Guigliarelli, B; Rothery, R A; Bertrand, P; Giordano, G; Blasco, F

    1998-05-19

    Most of the molybdoenzymes contain, in the amino-terminal region of their catalytic subunits, a conserved Cys group that in some cases binds an [Fe-S] cluster. In dissimilatory nitrate reductases, the first Cys residue of this motif is replaced by a conserved His residue. Site-directed mutagenesis of this residue (His-50) was performed on the NarG subunit from Escherichia coli nitrate reductase A. The results obtained by EPR spectroscopy enable us to exclude the implication of this residue in [Fe-S] binding. Additionally, we showed that the His-50 residue does not coordinate the molybdenum atom, but its substitution by Cys or Ser introduces a perturbation of the hydrogen bonding network around the molybdenum cofactor. From potentiometric studies, it is proposed that the high-pH and the low-pH forms of the Mo(V) are both involved during the redox turnover of the enzyme. Perturbation of the Mo(V) pKV value might be responsible for the low activity reported in the His-50-Cys mutant enzyme. A catalytic model is proposed in which the protonation/deprotonation of the Mo(V) species is an essential step. Thus, one of the two protons involved in the catalytic cycle could be the one coupled to the molybdenum atom in the dissimilatory nitrate reductase of E. coli. PMID:9585550

  15. Immunological Effect of Subunit Influenza Vaccine Entrapped by Liposomes

    Institute of Scientific and Technical Information of China (English)

    SHUI-HUA ZHANG; JIA-XU LIANG; SHU-YAN DAI; XIAO-LIN QIU; YAN-RONG YI; YUN PAN

    2009-01-01

    Objective To elevate the immunological effect of subunit influenza vaccine in infants and aged people (over 60) using liposomal adjuvant in the context of its relatively low immunity and to investigate the relation between vaccine antigens and liposomal characteristics. Methods Several formulations of liposomal subunit influenza vaccine were prepared. Their relevant characteristics were investigated to optimize the preparation method. Antisera obtained from immunizinged mice were used to evaluate the antibody titers of various samples by HI and ELISA. Results Liposomal trivalent influenza vaccine prepared by film evaporation in combinedation with freeze-drying significantly increased its immunological effect in SPF Balb/c mice. Liposomal vaccine stimulated the antibody titer of H3N2, H1N1, and B much stronger than conventional influenza vaccine. As a result, liposomal vaccine (mean size: 4.5-5.5 μm, entrapment efficiency: 30%-40%) significantly increased the immunological effect of subunit influenza vaccine. Conclusion The immune effect of liposomal vaccine depends on different antigens, and enhanced immunity is not positively correlated with the mean size of liposome or its entrapped efficiency.

  16. Ribosomal small subunit domains radiate from a central core

    Science.gov (United States)

    Gulen, Burak; Petrov, Anton S.; Okafor, C. Denise; Vander Wood, Drew; O'Neill, Eric B.; Hud, Nicholas V.; Williams, Loren Dean

    2016-02-01

    The domain architecture of a large RNA can help explain and/or predict folding, function, biogenesis and evolution. We offer a formal and general definition of an RNA domain and use that definition to experimentally characterize the rRNA of the ribosomal small subunit. Here the rRNA comprising a domain is compact, with a self-contained system of molecular interactions. A given rRNA helix or stem-loop must be allocated uniquely to a single domain. Local changes such as mutations can give domain-wide effects. Helices within a domain have interdependent orientations, stabilities and interactions. With these criteria we identify a core domain (domain A) of small subunit rRNA. Domain A acts as a hub, linking the four peripheral domains and imposing orientational and positional restraints on the other domains. Experimental characterization of isolated domain A, and mutations and truncations of it, by methods including selective 2‧OH acylation analyzed by primer extension and circular dichroism spectroscopy are consistent with our architectural model. The results support the utility of the concept of an RNA domain. Domain A, which exhibits structural similarity to tRNA, appears to be an essential core of the small ribosomal subunit.

  17. Mutant GABA(A) receptor subunits in genetic (idiopathic) epilepsy.

    Science.gov (United States)

    Hirose, Shinichi

    2014-01-01

    The γ-aminobutyric acid receptor type A (GABAA receptor) is a ligand-gated chloride channel that mediates major inhibitory functions in the central nervous system. GABAA receptors function mainly as pentamers containing α, β, and either γ or δ subunits. A number of antiepileptic drugs have agonistic effects on GABAA receptors. Hence, dysfunctions of GABAA receptors have been postulated to play important roles in the etiology of epilepsy. In fact, mutations or genetic variations of the genes encoding the α1, α6, β2, β3, γ2, or δ subunits (GABRA1, GABRA6, GABRB2, GABRB3, GABRG2, and GABRD, respectively) have been associated with human epilepsy, both with and without febrile seizures. Epilepsy resulting from mutations is commonly one of following, genetic (idiopathic) generalized epilepsy (e.g., juvenile myoclonic epilepsy), childhood absence epilepsy, genetic epilepsy with febrile seizures, or Dravet syndrome. Recently, mutations of GABRA1, GABRB2, and GABRB3 were associated with infantile spasms and Lennox-Gastaut syndrome. These mutations compromise hyperpolarization through GABAA receptors, which is believed to cause seizures. Interestingly, most of the insufficiencies are not caused by receptor gating abnormalities, but by complex mechanisms, including endoplasmic reticulum (ER)-associated degradation, nonsense-mediated mRNA decay, intracellular trafficking defects, and ER stress. Thus, GABAA receptor subunit mutations are now thought to participate in the pathomechanisms of epilepsy, and an improved understanding of these mutations should facilitate our understanding of epilepsy and the development of new therapies. PMID:25194483

  18. Ribosomal small subunit domains radiate from a central core

    Science.gov (United States)

    Gulen, Burak; Petrov, Anton S.; Okafor, C. Denise; Vander Wood, Drew; O’Neill, Eric B.; Hud, Nicholas V.; Williams, Loren Dean

    2016-01-01

    The domain architecture of a large RNA can help explain and/or predict folding, function, biogenesis and evolution. We offer a formal and general definition of an RNA domain and use that definition to experimentally characterize the rRNA of the ribosomal small subunit. Here the rRNA comprising a domain is compact, with a self-contained system of molecular interactions. A given rRNA helix or stem-loop must be allocated uniquely to a single domain. Local changes such as mutations can give domain-wide effects. Helices within a domain have interdependent orientations, stabilities and interactions. With these criteria we identify a core domain (domain A) of small subunit rRNA. Domain A acts as a hub, linking the four peripheral domains and imposing orientational and positional restraints on the other domains. Experimental characterization of isolated domain A, and mutations and truncations of it, by methods including selective 2′OH acylation analyzed by primer extension and circular dichroism spectroscopy are consistent with our architectural model. The results support the utility of the concept of an RNA domain. Domain A, which exhibits structural similarity to tRNA, appears to be an essential core of the small ribosomal subunit. PMID:26876483

  19. Novel Metal Nanomaterials and Their Catalytic Applications

    Directory of Open Access Journals (Sweden)

    Jiaqing Wang

    2015-09-01

    Full Text Available In the rapidly developing areas of nanotechnology, nano-scale materials as heterogeneous catalysts in the synthesis of organic molecules have gotten more and more attention. In this review, we will summarize the synthesis of several new types of noble metal nanostructures (FePt@Cu nanowires, Pt@Fe2O3 nanowires and bimetallic Pt@Ir nanocomplexes; Pt-Au heterostructures, Au-Pt bimetallic nanocomplexes and Pt/Pd bimetallic nanodendrites; Au nanowires, CuO@Ag nanowires and a series of Pd nanocatalysts and their new catalytic applications in our group, to establish heterogeneous catalytic system in “green” environments. Further study shows that these materials have a higher catalytic activity and selectivity than previously reported nanocrystal catalysts in organic reactions, or show a superior electro-catalytic activity for the oxidation of methanol. The whole process might have a great impact to resolve the energy crisis and the environmental crisis that were caused by traditional chemical engineering. Furthermore, we hope that this article will provide a reference point for the noble metal nanomaterials’ development that leads to new opportunities in nanocatalysis.

  20. Catalytic site interactions in yeast OMP synthase

    DEFF Research Database (Denmark)

    Hansen, Michael Riis; Barr, Eric W.; Jensen, Kaj Frank;

    2014-01-01

    45 (2006) 5330-5342]. This behavior was investigated in the yeast enzyme by mutations in the conserved catalytic loop and 5-phosphoribosyl-1-diphosphate (PRPP) binding motif. Although the reaction is mechanistically sequential, the wild-type (WT) enzyme shows parallel lines in double reciprocal...

  1. Lignin Valorization using Heterogenous Catalytic Oxidation

    DEFF Research Database (Denmark)

    Melián Rodríguez, Mayra; Shunmugavel, Saravanamurugan; Kegnæs, Søren;

    is complex so different model compounds are often used to study lignin valorization. These model compounds contain the linkages present in lignin, simplifying catalytic analysis and present analytical challenges related to the study of the complicated lignin polymer and the plethora of products that could...

  2. Performance characterization of a hydrogen catalytic heater.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Terry Alan; Kanouff, Michael P.

    2010-04-01

    This report describes the performance of a high efficiency, compact heater that uses the catalytic oxidation of hydrogen to provide heat to the GM Hydrogen Storage Demonstration System. The heater was designed to transfer up to 30 kW of heat from the catalytic reaction to a circulating heat transfer fluid. The fluid then transfers the heat to one or more of the four hydrogen storage modules that make up the Demonstration System to drive off the chemically bound hydrogen. The heater consists of three main parts: (1) the reactor, (2) the gas heat recuperator, and (3) oil and gas flow distribution manifolds. The reactor and recuperator are integrated, compact, finned-plate heat exchangers to maximize heat transfer efficiency and minimize mass and volume. Detailed, three-dimensional, multi-physics computational models were used to design and optimize the system. At full power the heater was able to catalytically combust a 10% hydrogen/air mixture flowing at over 80 cubic feet per minute and transfer 30 kW of heat to a 30 gallon per minute flow of oil over a temperature range from 100 C to 220 C. The total efficiency of the catalytic heater, defined as the heat transferred to the oil divided by the inlet hydrogen chemical energy, was characterized and methods for improvement were investigated.

  3. Electrochemical Promotion of Catalytic Reactions Using

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cleemann, Lars Nilausen;

    2007-01-01

    This paper presents the results of a study on electrochemical promotion (EP) of catalytic reactions using Pt/C/polybenzimidazole(H3PO4)/Pt/C fuel cell performed by the Energy and Materials Science Group (Technical University of Denmark) during the last 6 years[1-4]. The development of our...

  4. Toward Facilitative Mentoring and Catalytic Interventions

    Science.gov (United States)

    Smith, Melissa K.; Lewis, Marilyn

    2015-01-01

    In TESOL teacher mentoring, giving advice can be conceptualized as a continuum, ranging from directive to facilitative feedback. The goal, over time, is to lead toward the facilitative end of the continuum and specifically to catalytic interventions that encourage self-reflection and autonomous learning. This study begins by examining research on…

  5. Catalytic treatment of diesel engines, NOx emissions

    International Nuclear Information System (INIS)

    Some aspects of the operation of diesel engines are revised together with the pollutant emissions they produce, as well as the available catalytic technologies for the treatment of diesel emissions. Furthermore the performance of a catalyst developed in the environmental catalysis group for NOx reduction using synthetic gas mixtures simulating the emissions from diesel engines is presented

  6. Catalytic Converters Maintain Air Quality in Mines

    Science.gov (United States)

    2014-01-01

    At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

  7. Rapid Deployment of Rich Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Richard S. Tuthill

    2004-06-10

    The overall objective of this research under the Turbines Program is the deployment of fuel flexible rich catalytic combustion technology into high-pressure ratio industrial gas turbines. The resulting combustion systems will provide fuel flexibility for gas turbines to burn coal derived synthesis gas or natural gas and achieve NO{sub x} emissions of 2 ppmvd or less (at 15 percent O{sub 2}), cost effectively. This advance will signify a major step towards environmentally friendly electric power generation and coal-based energy independence for the United States. Under Phase 1 of the Program, Pratt & Whitney (P&W) performed a system integration study of rich catalytic combustion in a small high-pressure ratio industrial gas turbine with a silo combustion system that is easily scalable to a larger multi-chamber gas turbine system. An implementation plan for this technology also was studied. The principal achievement of the Phase 1 effort was the sizing of the catalytic module in a manner which allowed a single reactor (rather than multiple reactors) to be used by the combustion system, a conclusion regarding the amount of air that should be allocated to the reaction zone to achieve low emissions, definition of a combustion staging strategy to achieve low emissions, and mechanical integration of a Ceramic Matrix Composite (CMC) combustor liner with the catalytic module.

  8. Catalytic dehydrogenations of ethylbenzene to styrene

    NARCIS (Netherlands)

    Nederlof, C.

    2012-01-01

    This research work on the catalytic dehydrogenation of ethylbenzene (EB) to styrene (ST) had a primary goal of developing improved catalysts for dehydrogenation processes both in CO2 as well as with O2 that can compete with the conventional dehydrogenation process in steam. In order to achieve this

  9. Shungite carbon catalytic effect on coal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Grigorieva, E.N.; Rozhkova, N.N. [Russian Academy of Sciences, Moscow (Russian Federation). Institute for High Temperature

    1999-07-01

    The catalytic ability of shungite carbon in reactions of coal organic matter models appeared to be due to its fullerene structure only. Transition metal sulphides present in shungite carbon are not active in the conditions of coal treatment. Shungite carbon was shown to exhibit an acceleration of thermolysis of coal and organic matter models, mainly dehydrogenation. 5 refs., 1 tabs.

  10. Toward a catalytic site in DNA

    DEFF Research Database (Denmark)

    Jakobsen, Ulla; Rohr, Katja; Vogel, Stefan

    2007-01-01

    A number of functionalized polyaza crown ether building blocks have been incorporated into DNA-conjugates as catalytic Cu(2+) binding sites. The effect of the DNA-conjugate catalyst on the stereochemical outcome of a Cu(2+)-catalyzed Diels-Alder reaction will be presented....

  11. Catalytic asymmetric synthesis of mycocerosic acid

    NARCIS (Netherlands)

    ter Horst, B.; Feringa, B.L.; J. Minnaard, A.

    2007-01-01

    The first catalytic asymmetric total synthesis of mycocerosic acid was achieved via the application of iterative enantioselective 1,4-addition reactions and allows for the efficient construction of 1,3-polymethyl arrays with full stereocontrol; further exemplified by the synthesis of tetramethyl-dec

  12. SELECTIVE CATALYTIC REDUCTION MERCURY FIELD SAMPLING PROJECT

    Science.gov (United States)

    A lack of data still exists as to the effect of selective catalytic reduction (SCR), selective noncatalytic reduction (SNCR), and flue gas conditioning on the speciation and removal of mercury (Hg) at power plants. This project investigates the impact that SCR, SNCR, and flue gas...

  13. Deformed epidermal autoregulatory factor-1 (DEAF1 interacts with the Ku70 subunit of the DNA-dependent protein kinase complex.

    Directory of Open Access Journals (Sweden)

    Philip J Jensik

    Full Text Available Deformed Epidermal Autoregulatory Factor 1 (DEAF1 is a transcription factor linked to suicide, cancer, autoimmune disorders and neural tube defects. To better understand the role of DEAF1 in protein interaction networks, a GST-DEAF1 fusion protein was used to isolate interacting proteins in mammalian cell lysates, and the XRCC6 (Ku70 and the XRCC5 (Ku80 subunits of DNA dependent protein kinase (DNA-PK complex were identified by mass spectrometry, and the DNA-PK catalytic subunit was identified by immunoblotting. Interaction of DEAF1 with Ku70 and Ku80 was confirmed to occur within cells by co-immunoprecipitation of epitope-tagged proteins, and was mediated through interaction with the Ku70 subunit. Using in vitro GST-pulldowns, interaction between DEAF1 and the Ku70 subunit was mapped to the DEAF1 DNA binding domain and the C-terminal Bax-binding region of Ku70. In transfected cells, DEAF1 and Ku70 colocalized to the nucleus, but Ku70 could not relocalize a mutant cytoplasmic form of DEAF1 to the nucleus. Using an in vitro kinase assay, DEAF1 was phosphorylated by DNA-PK in a DNA-independent manner. Electrophoretic mobility shift assays showed that DEAF1 or Ku70/Ku80 did not interfere with the DNA binding of each other, but DNA containing DEAF1 binding sites inhibited the DEAF1-Ku70 interaction. The data demonstrates that DEAF1 can interact with the DNA-PK complex through interactions of its DNA binding domain with the carboxy-terminal region of Ku70 that contains the Bax binding domain, and that DEAF1 is a potential substrate for DNA-PK.

  14. Hybridization of glutamate aspartate transaminase. Investigation of subunit interaction.

    Science.gov (United States)

    Boettcher, B; Martinez-Carrion, M

    1975-10-01

    Glutamate aspartate transaminase (EC 2.6.1.1) is a dimeric enzyme with identical subunits with each active site containing pyridoxal 5'-phosphate linked via an internal Shiff's base to a lysine residue. It is not known if these sites interact during catalysis but negative cooperativity has been reported for binding of the coenzyme (Arrio-Dupont, M. (1972), Eur. J. Biochem. 30, 307). Also nonequivalence of its subunits in binding 8-anilinonaphthalene-1-sulfonate (Harris, H.E., and Bayley, P. M. (1975), Biochem. J. 145, 125), in modification of only a single tyrosine with full loss of activity (Christen, P., and Riordan, J.F. (1970), Biochemistry 9, 3025), and following modification with 5,5'-dithiobis(2-nitrobenzoic acid) (Cournil, I., and Arrio-Dupont, M. (1973), Biochemie 55, 103) has been reported. However, steady-state and transient kinetic methods as well as direct titration of the active site chromophore with substrates and substrate analogs have not revealed any cooperative phenomena (Braunstein, A. E. (1973), Enzymes, 3rd Ed. 9, 379). It was therefore decided that a more direct approach should be used to clarify the quistion of subunit interaction during the covalent phase of catalysis. To this end a hybrid method was devised in which a hybrid transaminase was prepared which contained one subunit with a functional active site while the other subunit has the internal Shiff's base reduced with NaBH4. The specific activities and amount of "actively bound" pyridoxal 5'-phosphate are both in a 2:1 ratio for the native and hybrid forms. Comparison of the steady-state kinetic properties of the hybrid and native enzyme forms shows that both forms gave parallel double reciprocal plots which is characteristic of the Ping-Pong Bi-Bi mechanism of transamination. The Km values for the substrates L-aspartic acid and alpha-ketoglutaric acid are nearly identical while the Vmax value for the hybrid is one-half the value of the native transaminase. It therefore appears that

  15. Comparison of Large Subunits of Type II DNA-dependent RNA Polymerases from Higher Plants.

    Science.gov (United States)

    Kidd, G H; Link, G; Bogorad, L

    1979-10-01

    Two-dimensional tryptic mapping of (125)I-labeled polypeptides has been employed to compare the large subunits of type II DNA-dependent RNA polymerases from maize, parsley (Petroselinum sativum), and wheat. Maps of the 220 kilodalton (kd) and 140 kd subunits from wheat RNA polymerase II differ from those of the corresponding subunits from parsley enzyme II. The 180 kd subunits from maize and parsley type II enzymes also yield dissimilar tryptic maps. Thus, despite similarities in molecular mass, the large subunits of wheat, parsley, and maize type II RNA polymerases are unique to each individual plant species. PMID:16661032

  16. On the multiple roles of the voltage gated sodium channel β1 subunit in genetic diseases

    Directory of Open Access Journals (Sweden)

    Debora eBaroni

    2015-05-01

    Full Text Available Voltage-gated sodium channels are intrinsic plasma membrane proteins that initiate the action potential in electrically excitable cells. They are composed of a pore-forming α-subunit and associated β-subunits. The β1-subunit was the first accessory subunit to be cloned. It can be important for controlling cell excitability and modulating multiple aspects of sodium channel physiology. Mutations of β1 are implicated in a wide variety of inherited pathologies, including epilepsy and cardiac conduction diseases. This review summarizes β1-subunit related channelopathies pointing out the current knowledge concerning their genetic background and their underlying molecular mechanisms.

  17. Regulation of expression of a soybean storage protein subunit gene: Final report

    International Nuclear Information System (INIS)

    In an effort to determine why methionine decreases the level of the conglycinin β-subunit in cultured soybean seeds, we have established that: (1) methionine does not accelerate the degradation of the β-subunit; (2) that methionine is probably not acting by methylating the β-subunit gene; (3) that methionine is preventing the appearance of a translatable β-subunit mRNA; (4) that methionine is probably not accelerating the degradation of the β-subunit mRNA; and (5) methionine causes a marked increase in a small (0.7 kb) poly A+ RNA. 6 refs., 4 figs., 2 tabs

  18. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  19. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  20. Developmental and Regulatory Functions of Na(+) Channel Non-pore-forming β Subunits.

    Science.gov (United States)

    Winters, J J; Isom, L L

    2016-01-01

    Voltage-gated Na(+) channels (VGSCs) isolated from mammalian neurons are heterotrimeric complexes containing one pore-forming α subunit and two non-pore-forming β subunits. In excitable cells, VGSCs are responsible for the initiation of action potentials. VGSC β subunits are type I topology glycoproteins, containing an extracellular amino-terminal immunoglobulin (Ig) domain with homology to many neural cell adhesion molecules (CAMs), a single transmembrane segment, and an intracellular carboxyl-terminal domain. VGSC β subunits are encoded by a gene family that is distinct from the α subunits. While α subunits are expressed in prokaryotes, β subunit orthologs did not arise until after the emergence of vertebrates. β subunits regulate the cell surface expression, subcellular localization, and gating properties of their associated α subunits. In addition, like many other Ig-CAMs, β subunits are involved in cell migration, neurite outgrowth, and axon pathfinding and may function in these roles in the absence of associated α subunits. In sum, these multifunctional proteins are critical for both channel regulation and central nervous system development. PMID:27586289

  1. Generalized epilepsy with febrile seizures plus-associated sodium channel beta1 subunit mutations severely reduce beta subunit-mediated modulation of sodium channel function.

    Science.gov (United States)

    Xu, R; Thomas, E A; Gazina, E V; Richards, K L; Quick, M; Wallace, R H; Harkin, L A; Heron, S E; Berkovic, S F; Scheffer, I E; Mulley, J C; Petrou, S

    2007-08-10

    Two novel mutations (R85C and R85H) on the extracellular immunoglobulin-like domain of the sodium channel beta1 subunit have been identified in individuals from two families with generalized epilepsy with febrile seizures plus (GEFS+). The functional consequences of these two mutations were determined by co-expression of the human brain NaV1.2 alpha subunit with wild type or mutant beta1 subunits in human embryonic kidney (HEK)-293T cells. Patch clamp studies confirmed the regulatory role of beta1 in that relative to NaV1.2 alone the NaV1.2+beta1 currents had right-shifted voltage dependence of activation, fast and slow inactivation and reduced use dependence. In addition, the NaV1.2+beta1 current entered fast inactivation slightly faster than NaV1.2 channels alone. The beta1(R85C) subunit appears to be a complete loss of function in that none of the modulating effects of the wild type beta1 were observed when it was co-expressed with NaV1.2. Interestingly, the beta1(R85H) subunit also failed to modulate fast kinetics, however, it shifted the voltage dependence of steady state slow inactivation in the same way as the wild type beta1 subunit. Immunohistochemical studies revealed cell surface expression of the wild type beta1 subunit and undetectable levels of cell surface expression for both mutants. The functional studies suggest association of the beta1(R85H) subunit with the alpha subunit where its influence is limited to modulating steady state slow inactivation. In summary, the mutant beta1 subunits essentially fail to modulate alpha subunits which could increase neuronal excitability and underlie GEFS+ pathogenesis. PMID:17629415

  2. Distinct conformational changes in activated agonist-bound and agonist-free glycine receptor subunits

    DEFF Research Database (Denmark)

    Pless, Stephan Alexander; Lynch, Joseph W

    2009-01-01

    glycine-free or a glycine-bound subunit. Agonist-free subunits were created by incorporating T204A and R65K mutations, which disrupted glycine binding to both (+) and (-) subunit interfaces. In heteromeric receptors comprising wild-type and R65K,T204A,R271C triple-mutant subunits, the fluorescence...... response exhibited a drastically reduced glycine sensitivity relative to the current response. Two conclusions can be drawn from this. First, because the labeled glycine-free subunits were activated by glycine binding to neighboring wild-type subunits, our results provide evidence for a cooperative...... activation mechanism. However, because the fluorescent label on glycine-free subunits does not reflect movements at the channel gate, we conclude that glycine binding also produces a local non-concerted conformational change that is not essential for receptor activation....

  3. The Conservation of Structure and Mechanism of Catalytic Action in a Family of Thiamin Pyrophosphate (TPP)-dependent Enzymes

    Science.gov (United States)

    Dominiak, P.; Ciszak, Ewa

    2004-01-01

    Thiamin pyrophosphate (TPP)-dependent enzymes are a divergent family of TPP and metal ion binding proteins that perform a wide range of functions with the common decarboxylation steps of a -(O=)C-C(OH)- fragment of alpha-ketoacids and alpha- hydroxyaldehydes. To determine how structure and catalytic action are conserved in the context of large sequence differences existing within this family of enzymes, we have carried out an analysis of TPP-dependent enzymes of known structures. The common structure of TPP-dependent enzymes is formed at the interface of four alpha/beta domains from at least two subunits, which provide for two metal and TPP-binding sites. Residues around these catalytic sites are conserved for functional purpose, while those further away from TPP are conserved for structural reasons. Together they provide a network of contacts required for flip-flop catalytic action within TPP-dependent enzymes. Thus our analysis defines a TPP-action motif that is proposed for annotating TPP-dependent enzymes for advancing functional proteomics.

  4. A threonine stabilizes the NiC and NiR catalytic intermediates of [NiFe]-hydrogenase.

    Science.gov (United States)

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-03-27

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production.

  5. Reforming of methane in tubes with a catalytic active wall

    International Nuclear Information System (INIS)

    The heterogeneous steam reforming process in tubes with catalytic active inner surface is studied. The purpose of this ivestigation is to find a method of predicting the reaction rate of the catalytic conversion of methane by steam. The dependency of the reaction rate upon the temperature, pressure, gas composition, Reynolds number, geometrical sizes of tubes and catalytic behaviour of the catalytic active inner wall of these tubes has been examined. It was found that the reaction rate mainly depends on the temperature. The reaction rate is limited by the catalytic behaviour and the heat resisting properties of the materials used. (author)

  6. Human mediator subunit MED15 promotes transcriptional activation.

    Science.gov (United States)

    Nakatsubo, Takuya; Nishitani, Saori; Kikuchi, Yuko; Iida, Satoshi; Yamada, Kana; Tanaka, Aki; Ohkuma, Yoshiaki

    2014-10-01

    In eukaryotes, the Mediator complex is an essential transcriptional cofactor of RNA polymerase II (Pol II). In humans, it contains up to 30 subunits and consists of four modules: head, middle, tail, and CDK/Cyclin. One of the subunits, MED15, is located in the tail module, and was initially identified as Gal11 in budding yeast, where it plays an essential role in the transcriptional regulation of galactose metabolism with the potent transcriptional activator Gal4. For this reason, we investigated the function of the human MED15 subunit (hMED15) in transcriptional activation. First, we measured the effect of hMED15 knockdown on cell growth in HeLa cells. The growth rate was greatly reduced. By immunostaining, we observed the colocalization of hMED15 with the general transcription factors TFIIE and TFIIH in the nucleus. We measured the effects of siRNA-mediated knockdown of hMED15 on transcriptional activation using two different transcriptional activators, VP16 and SREBP1a. Treatment with siRNAs reduced transcriptional activation, and this reduction could be rescued by overexpression of HA/Flag-tagged, wild-type hMED15. To investigate hMED15 localization, we treated human MCF-7 cells with the MDM2 inhibitor Nutlin-3, thus inducing p21 transcription. We found that hMED15 localized to both the p53 binding site and the p21 promoter region, along with TFIIE and TFIIH. These results indicate that hMED15 promotes transcriptional activation.

  7. Method and apparatus for a catalytic firebox reactor

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Lance L. (North Haven, CT); Etemad, Shahrokh (Trumbull, CT); Ulkarim, Hasan (Hamden, CT); Castaldi, Marco J. (Bridgeport, CT); Pfefferle, William C. (Madison, CT)

    2001-01-01

    A catalytic firebox reactor employing an exothermic catalytic reaction channel and multiple cooling conduits for creating a partially reacted fuel/oxidant mixture. An oxidation catalyst is deposited on the walls forming the boundary between the multiple cooling conduits and the exothermic catalytic reaction channel, on the side of the walls facing the exothermic catalytic reaction channel. This configuration allows the oxidation catalyst to be backside cooled by any fluid passing through the cooling conduits. The heat of reaction is added to both the fluid in the exothermic catalytic reaction channel and the fluid passing through the cooling conduits. After discharge of the fluids from the exothermic catalytic reaction channel, the fluids mix to create a single combined flow. A further innovation in the reactor incorporates geometric changes in the exothermic catalytic reaction channel to provide streamwise variation of the velocity of the fluids in the reactor.

  8. From Catalytic Reaction Networks to Protocells

    Science.gov (United States)

    Kaneko, Kunihiko

    2013-12-01

    In spite of recent advances, there still remains a large gape between a set of chemical reactions and a biological cell. Here we discuss several theoretical efforts to fill in the gap. The topics cover (i) slow relaxation to equilibrium due to glassy behavior in catalytic reaction networks (ii) consistency between molecule replication and cell growth, as well as energy metabolism (iii) control of a system by minority molecules in mutually catalytic system, which work as a carrier of genetic information, and leading to evolvability (iv) generation of a compartmentalized structure as a cluster of molecules centered around the minority molecule, and division of the cluster accompanied by the replication of minority molecule (v) sequential, logical process over several states from concurrent reaction dynamics, by taking advantage of discreteness in molecule number.

  9. Janus droplet as a catalytic micromotor

    CERN Document Server

    Shklyaev, Sergey

    2015-01-01

    Self-propulsion of a Janus droplet in a solution of surfactant, which reacts on a half of a drop surface, is studied theoretically. The droplet acts as a catalytic motor creating a concentration gradient, which generates its surface-tension-driven motion; the self-propulsion speed is rather high, $60\\; {\\rm \\mu m/s}$ and more. This catalytic motor has several advantages over other micromotors: simple manufacturing, easily attained neutral buoyancy. In contrast to a single-fluid droplet, which demonstrates a self-propulsion as a result of symmetry breaking instability, for Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers. The paper was finalized and submitted by Denis S. Goldobin after Sergey Sklyaev had sadly passed away on June 2, 2014.

  10. The phosphorylation pattern of bovine heart complex I subunits

    DEFF Research Database (Denmark)

    Palmisano, Giuseppe; Sardanelli, Anna Maria; Signorile, Anna;

    2007-01-01

    The phosphoproteome of bovine heart complex I of the respiratory chain has been analysed with a procedure based on nondenaturing gel electrophoretic separation of complex I from small quantities of mitochondria samples, in-gel digestion, in combination with phosphopeptide enrichment by titanium...... dioxide and MS. The results, complemented by analyses of purified samples of complex I, showed phosphorylation of five subunits of the complex, 42 kDa (human gene NDUFA10), ESSS, B14.5a (human gene NDUFA7), B14.5b (human gene NDUFC2) and B16.6 (GRIM-19). MS also revealed the presence of phosphorylated...

  11. Posttranslational modifications in the CP43 subunit of photosystem II

    OpenAIRE

    Anderson, Lorraine B.; Maderia, Melissa; Ouellette, Anthony J. A.; Putnam-Evans, Cindy; Higgins, LeeAnn; Krick, Thomas; MacCoss, Michael J; Lim, Hanjo; Yates, John R.; Barry, Bridgette A.

    2002-01-01

    Photosystem II (PSII) catalyzes the light-driven oxidation of water and the reduction of plastoquinone; the oxidation of water occurs at a cluster of four manganese. The PSII CP43 subunit functions in light harvesting, and mutations in the fifth luminal loop (E) of CP43 have established its importance in PSII structure and/or assembly [Kuhn, M. G. & Vermaas, V. F. J. (1993) Plant Mol. Biol. 23, 123–133]. The sequence A350PWLEPLR357 in luminal loop E is conserved in CP43 genes from 50 organism...

  12. Effects of metal ions on recombinant calcineurin A subunit

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Effects of metal ions on activities and solution conformations of calcineurin A subunit have been examined.The ability of several metal ions to activate calcineurin A has been tested with Ni2+>Mn2+>Mg2+/Ca2+.The corresponding CD spectra and intrinsic fluorescent emission spectra show that calcineurin A exists in different metal ion-dependent conformation states.Effects of the different concentritions of Ni2+ on activities and solution conformations of calcineurin A have been tested too.Results indicate that effects of these metal ions to activate calcineurin are due to their conformational changes.

  13. Radiation damage to DNA: electron scattering from the backbone subunits

    CERN Document Server

    Tonzani, S; Greene, Chris H.; Tonzani, Stefano

    2006-01-01

    In the context of damage to DNA by low-energy electrons, we carry out calculations of electron scattering from tetrahydrofuran and phosphoric acid, models of the subunits in the DNA backbone, as a first step in simulating the electron capture process that occurs in the cell. In the case of tetrahydrofuran, we also compare with previous theoretical and experimental data. A comparison of the shape of the resonant structures to virtual orbitals is also performed to gain insight into the systematic connections with electron scattering from similar molecules and dissociative electron attachment experiments.

  14. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Molten Metal Technology was awarded a contract to demonstrate the applicability of the Catalytic Extraction Process, a proprietary process that could be applied to US DOE's inventory of low level mixed waste. This paper is a description of that technology, and included within this document are discussions of: (1) Program objectives, (2) Overall technology review, (3) Organic feed conversion to synthetic gas, (4) Metal, halogen, and transuranic recovery, (5) Demonstrations, (6) Design of the prototype facility, and (7) Results

  15. Materials for High-Temperature Catalytic Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Ersson, Anders

    2003-04-01

    Catalytic combustion is an environmentally friendly technique to combust fuels in e.g. gas turbines. Introducing a catalyst into the combustion chamber of a gas turbine allows combustion outside the normal flammability limits. Hence, the adiabatic flame temperature may be lowered below the threshold temperature for thermal NO{sub X} formation while maintaining a stable combustion. However, several challenges are connected to the application of catalytic combustion in gas turbines. The first part of this thesis reviews the use of catalytic combustion in gas turbines. The influence of the fuel has been studied and compared over different catalyst materials. The material section is divided into two parts. The first concerns bimetallic palladium catalysts. These catalysts showed a more stable activity compared to their pure palladium counterparts for methane combustion. This was verified both by using an annular reactor at ambient pressure and a pilot-scale reactor at elevated pressures and flows closely resembling the ones found in a gas turbine combustor. The second part concerns high-temperature materials, which may be used either as active or washcoat materials. A novel group of materials for catalysis, i.e. garnets, has been synthesised and tested in combustion of methane, a low-heating value gas and diesel fuel. The garnets showed some interesting abilities especially for combustion of low-heating value, LHV, gas. Two other materials were also studied, i.e. spinels and hexa aluminates, both showed very promising thermal stability and the substituted hexa aluminates also showed a good catalytic activity. Finally, deactivation of the catalyst materials was studied. In this part the sulphur poisoning of palladium, platinum and the above-mentioned complex metal oxides has been studied for combustion of a LHV gas. Platinum and surprisingly the garnet were least deactivated. Palladium was severely affected for methane combustion while the other washcoat materials were

  16. Ubiquitous "glassy" relaxation in catalytic reaction networks

    OpenAIRE

    Awazu, Akinori; Kaneko, Kunihiko

    2009-01-01

    Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show two types of salient behaviors that are reminiscent of glassy behavior: slow relaxation along with the logarithmic time dependence of the correlation function and the emergence of plateaus in the rel...

  17. Thermal and catalytic pyrolysis of plastic waste

    OpenAIRE

    Débora Almeida; Maria de Fátima Marques

    2016-01-01

    Abstract The amount of plastic waste is growing every year and with that comes an environmental concern regarding this problem. Pyrolysis as a tertiary recycling process is presented as a solution. Pyrolysis can be thermal or catalytical and can be performed under different experimental conditions. These conditions affect the type and amount of product obtained. With the pyrolysis process, products can be obtained with high added value, such as fuel oils and feedstock for new products. Zeolit...

  18. Selective Catalytic Reduction of NO with Methane

    Institute of Scientific and Technical Information of China (English)

    Xiang Gao; Qi Yu; Limin Chen

    2003-01-01

    The removal of nitrogen oxides from exhaust gases has attracted great attention in recent years, and many approaches have been developed depending on the application. Methane, the main component of natural gas, has great potential as a NO reductant. In this paper, a number of catalysts previous reported for this catalytic reduction of NO have been reviewed, including a direct comparison of the relative activities and effective factors of the catalysts. Reaction mechanisms have also been explored preliminarily.

  19. Catalytic fast pyrolysis of lignocellulosic biomass

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changjun; Wang, Huamin; Karim, Ayman M.; Sun, Junming; Wang, Yong

    2014-11-21

    Increasing energy demand, especially in the transportation sector, and soaring CO2 emissions necessitate the exploitation of renewable sources of energy. Despite the large variety of new energy Q3 carriers, liquid hydrocarbon still appears to be the most attractive and feasible form of transportation fuel taking into account the energy density, stability and existing infrastructure. Biomass is an abundant, renewable source of energy; however, utilizing it in a cost-effective way is still a substantial challenge. Lignocellulose is composed of three major biopolymers, namely cellulose, hemicellulose and lignin. Fast pyrolysis of biomass is recognized as an efficient and feasible process to selectively convert lignocellulose into a liquid fuel—bio-oil. However bio-oil from fast pyrolysis contains a large amount of oxygen, distributed in hundreds of oxygenates. These oxygenates are the cause of many negative properties, such as low heating values, high corrosiveness, high viscosity, and instability; they also greatly Q4 limit the application of bio-oil particularly as transportation fuel. Hydrocarbons derived from biomass are most attractive because of their high energy density and compatibility with the existing infrastructure. Thus, converting lignocellulose into transportation fuels via catalytic fast pyrolysis has attracted much attention. Many studies related to catalytic fast pyrolysis of biomass have been published. The main challenge of this process is the development of active and stable catalysts that can deal with a large variety of decomposition intermediates from lignocellulose. This review starts with the current understanding of the chemistry in fast pyrolysis of lignocellulose and focuses on the development of catalysts in catalytic fast pyrolysis. Recent progress in the experimental studies on catalytic fast pyrolysis of biomass is also summarized with the emphasis on bio-oil yields and quality.

  20. Materials for High-Temperature Catalytic Combustion

    OpenAIRE

    Ersson, Anders

    2003-01-01

    Catalytic combustion is an environmentally friendlytechnique to combust fuels in e.g. gas turbines. Introducing acatalyst into the combustion chamber of a gas turbine allowscombustion outside the normal flammability limits. Hence, theadiabatic flame temperature may be lowered below the thresholdtemperature for thermal NOXformation while maintaining a stable combustion.However, several challenges are connected to the application ofcatalytic combustion in gas turbines. The first part of thisthe...

  1. Control of a catalytic fluid cracker

    Energy Technology Data Exchange (ETDEWEB)

    Arbel, A.; Huang, Z.; Rinard, I.; Shinnar, R.

    1993-12-13

    Control offers an important tool for savings in refineries, mainly by integration of process models into on-line control. This paper is part of a research effort to better understand problems of partial control; control of a Fluid Catalytic Cracker (FCC) is used as example. Goal is to understand better the control problems of an FCC in context of model based control of a refinery, and to understand the general problem of designing partial control systems.

  2. Probing catalytic rate enhancement during intramembrane proteolysis.

    Science.gov (United States)

    Arutyunova, Elena; Smithers, Cameron C; Corradi, Valentina; Espiritu, Adam C; Young, Howard S; Tieleman, D Peter; Lemieux, M Joanne

    2016-09-01

    Rhomboids are ubiquitous intramembrane serine proteases involved in various signaling pathways. While the high-resolution structures of the Escherichia coli rhomboid GlpG with various inhibitors revealed an active site comprised of a serine-histidine dyad and an extensive oxyanion hole, the molecular details of rhomboid catalysis were unclear because substrates are unknown for most of the family members. Here we used the only known physiological pair of AarA rhomboid with its psTatA substrate to decipher the contribution of catalytically important residues to the reaction rate enhancement. An MD-refined homology model of AarA was used to identify residues important for catalysis. We demonstrated that the AarA active site geometry is strict and intolerant to alterations. We probed the roles of H83 and N87 oxyanion hole residues and determined that substitution of H83 either abolished AarA activity or reduced the transition state stabilization energy (ΔΔG‡) by 3.1 kcal/mol; substitution of N87 decreased ΔΔG‡ by 1.6-3.9 kcal/mol. Substitution M154, a residue conserved in most rhomboids that stabilizes the catalytic general base, to tyrosine, provided insight into the mechanism of nucleophile generation for the catalytic dyad. This study provides a quantitative evaluation of the role of several residues important for hydrolytic efficiency and oxyanion stabilization during intramembrane proteolysis. PMID:27071148

  3. Catalytic pyrolysis of olive mill wastewater sludge

    Science.gov (United States)

    Abdellaoui, Hamza

    From 2008 to 2013, an average of 2,821.4 kilotons/year of olive oil were produced around the world. The waste product of the olive mill industry consists of solid residue (pomace) and wastewater (OMW). Annually, around 30 million m3 of OMW are produced in the Mediterranean area, 700,000 m3 year?1 in Tunisia alone. OMW is an aqueous effluent characterized by an offensive smell and high organic matter content, including high molecular weight phenolic compounds and long-chain fatty acids. These compounds are highly toxic to micro-organisms and plants, which makes the OMW a serious threat to the environment if not managed properly. The OMW is disposed of in open air evaporation ponds. After evaporation of most of the water, OMWS is left in the bottom of the ponds. In this thesis, the effort has been made to evaluate the catalytic pyrolysis process as a technology to valorize the OMWS. The first section of this research showed that 41.12 wt. % of the OMWS is mostly lipids, which are a good source of energy. The second section proved that catalytic pyrolysis of the OMWS over red mud and HZSM-5 can produce green diesel, and 450 °C is the optimal reaction temperature to maximize the organic yields. The last section revealed that the HSF was behind the good fuel-like properties of the OMWS catalytic oils, whereas the SR hindered the bio-oil yields and quality.

  4. Catalytic applications of bio-inspired nanomaterials

    Science.gov (United States)

    Pacardo, Dennis Kien Balaong

    The biomimetic synthesis of Pd nanoparticles was presented using the Pd4 peptide, TSNAVHPTLRHL, isolated from combinatorial phage display library. Using this approach, nearly monodisperse and spherical Pd nanoparticles were generated with an average diameter of 1.9 +/- 0.4 nm. The peptide-based nanocatalyst were employed in the Stille coupling reaction under energy-efficient and environmentally friendly reaction conditions of aqueous solvent, room temperature and very low catalyst loading. To this end, the Pd nanocatalyst generated high turnover frequency (TOF) value and quantitative yields using ≥ 0.005 mol% Pd as well as catalytic activities with different aryl halides containing electron-withdrawing and electron-donating groups. The Pd4-capped Pd nanoparticles followed the atom-leaching mechanism and were found to be selective with respect to substrate identity. On the other hand, the naturally-occurring R5 peptide (SSKKSGSYSGSKGSKRRIL) was employed in the synthesis of biotemplated Pd nanomaterials which showed morphological changes as a function of Pd:peptide ratio. TOF analysis for hydrogenation of olefinic alcohols showed similar catalytic activity regardless of nanomorphology. Determination of catalytic properties of these bio-inspired nanomaterials are important as they serve as model system for alternative green catalyst with applications in industrially important transformations.

  5. Highly sensitive catalytic spectrophotometric determination of ruthenium

    Science.gov (United States)

    Naik, Radhey M.; Srivastava, Abhishek; Prasad, Surendra

    2008-01-01

    A new and highly sensitive catalytic kinetic method (CKM) for the determination of ruthenium(III) has been established based on its catalytic effect on the oxidation of L-phenylalanine ( L-Pheala) by KMnO 4 in highly alkaline medium. The reaction has been followed spectrophotometrically by measuring the decrease in the absorbance at 526 nm. The proposed CKM is based on the fixed time procedure under optimum reaction conditions. It relies on the linear relationship where the change in the absorbance (Δ At) versus added Ru(III) amounts in the range of 0.101-2.526 ng ml -1 is plotted. Under the optimum conditions, the sensitivity of the proposed method, i.e. the limit of detection corresponding to 5 min is 0.08 ng ml -1, and decreases with increased time of analysis. The method is featured with good accuracy and reproducibility for ruthenium(III) determination. The ruthenium(III) has also been determined in presence of several interfering and non-interfering cations, anions and polyaminocarboxylates. No foreign ions interfered in the determination ruthenium(III) up to 20-fold higher concentration of foreign ions. In addition to standard solutions analysis, this method was successfully applied for the quantitative determination of ruthenium(III) in drinking water samples. The method is highly sensitive, selective and very stable. A review of recently published catalytic spectrophotometric methods for the determination of ruthenium(III) has also been presented for comparison.

  6. Insights into the catalytic mechanism of 16S rRNA methyltransferase RsmE (m³U1498) from crystal and solution structures.

    Science.gov (United States)

    Zhang, Heng; Wan, Hua; Gao, Zeng-Qiang; Wei, Yong; Wang, Wen-Jia; Liu, Guang-Feng; Shtykova, Eleonora V; Xu, Jian-Hua; Dong, Yu-Hui

    2012-11-01

    RsmE is the founding member of a new RNA methyltransferase (MTase) family responsible for methylation of U1498 in 16S ribosomal RNA in Escherichia coli. It is well conserved across bacteria and plants and may play an important role in ribosomal intersubunit communication. The crystal structure in monomer showed that it consists of two distinct but structurally related domains: the PUA (pseudouridine synthases and archaeosine-specific transglycosylases)-like RNA recognition and binding domain and the conserved MTase domain with a deep trefoil knot. Analysis of small-angle X-ray scattering data revealed that RsmE forms a flexible dimeric conformation that may be essential for substrate binding. The S-adenosyl-l-methionine (AdoMet)-binding characteristic determined by isothermal titration calorimetry suggested that there is only one AdoMet molecule bound in the subunit of the homodimer. In vitro methylation assay of the mutants based on the RsmE-AdoMet-uridylic acid complex model showed key residues involved in substrate binding and catalysis. Comprehensive comparisons of RsmE with closely related MTases, combined with the biochemical experiments, indicated that the MTase domain of one subunit in dimeric RsmE is responsible for binding of one AdoMet molecule and catalytic process while the PUA-like domain in the other subunit is mainly responsible for recognition of one substrate molecule (the ribosomal RNA fragment and ribosomal protein complex). The methylation process is required by collaboration of both subunits, and dimerization is functionally critical for catalysis. In general, our study provides new information on the structure-function relationship of RsmE and thereby suggests a novel catalytic mechanism.

  7. Thermostable cross-protective subunit vaccine against Brucella species.

    Science.gov (United States)

    Cherwonogrodzky, John W; Barabé, Nicole D; Grigat, Michelle L; Lee, William E; Poirier, Robert T; Jager, Scott J; Berger, Bradley J

    2014-12-01

    A subunit vaccine candidate was produced from Brucella suis 145 (biovar 4; expressing both the A antigen of Brucella abortus and the M antigen of Brucella melitensis). The preparation consisted mostly of polysaccharide (PS; >90% [wt/wt]; both cell-associated PS and exo-PS were combined) and a small amount of protein (1 to 3%) with no apparent nucleic acids. Vaccinated mice were protected (these had a statistically significant reduction in bacterial colonization compared to that of unvaccinated controls) when challenged with representative strains of three Brucella species most pathogenic for humans, i.e., B. abortus, B. melitensis, and B. suis. As little as 1 ng of the vaccine, without added adjuvant, protected mice against B. suis 145 infection (5 × 10(5) CFU), and a single injection of 1 μg of this subunit vaccine protected mice from B. suis 145 challenge for at least 14 months. A single immunization induced a serum IgG response to Brucella antigens that remained elevated for up to 9 weeks. The use of heat (i.e., boiling-water bath, autoclaving) in the vaccine preparation showed that it was thermostable. This method also ensured safety and security. The vaccine produced was immunogenic and highly protective against multiple strains of Brucella and represents a promising candidate for further evaluation.

  8. Fungal mediator tail subunits contain classical transcriptional activation domains.

    Science.gov (United States)

    Liu, Zhongle; Myers, Lawrence C

    2015-04-01

    Classical activation domains within DNA-bound eukaryotic transcription factors make weak interactions with coactivator complexes, such as Mediator, to stimulate transcription. How these interactions stimulate transcription, however, is unknown. The activation of reporter genes by artificial fusion of Mediator subunits to DNA binding domains that bind to their promoters has been cited as evidence that the primary role of activators is simply to recruit Mediator. We have identified potent classical transcriptional activation domains in the C termini of several tail module subunits of Saccharomyces cerevisiae, Candida albicans, and Candida dubliniensis Mediator, while their N-terminal domains are necessary and sufficient for their incorporation into Mediator but do not possess the ability to activate transcription when fused to a DNA binding domain. This suggests that Mediator fusion proteins actually are functioning in a manner similar to that of a classical DNA-bound activator rather than just recruiting Mediator. Our finding that deletion of the activation domains of S. cerevisiae Med2 and Med3, as well as C. dubliniensis Tlo1 (a Med2 ortholog), impairs the induction of certain genes shows these domains function at native promoters. Activation domains within coactivators are likely an important feature of these complexes and one that may have been uniquely leveraged by a common fungal pathogen.

  9. IMMUNOLOGICAL RESPONSE IN BOVINE LYMPH NODES STIMULATED WITH SUBUNITS VACCINES

    Directory of Open Access Journals (Sweden)

    Gabriel Andres Tafur Gomez

    2013-01-01

    Full Text Available The vaccination process belongs to the public health intervention methodologies that help prevent infections. Vaccinations performed successfully in the history of medicine reported the significance of this procedure to increase the quality of life, prevent zoonoses and improve animal production. Vaccine emergence remained without exact rules for a long time, maintaining a close relationship with pathogens. However, subunit vaccines, with a difference from the classical idea of protective immunity with microorganisms showed it is possible to trigger T-dependent responses with peptide, revealing new rules for vaccine development. This vaccination process starts by the modulation chance of adaptive immune response through peptide sequences process by APCs for immune synapse formation interceded for pMHC-TCR as a scaffold to T cells priming. In this way the immunological signal triggered by immune synapses is amplified in lymph nodes. As a consequence, T and B cells modulated by peptide activity interact between the B cell follicles region and T cell aggregates, which constitute the paracortical region of secondary lymphoid tissue to form connate unions as a prerequisite for clonal amplification and subsequent immunological memory. Indicating the knowledge of the mechanisms of immune response generated by peptides immunization is essential for understanding modulation, amplification and immune protection as demands for good subunits vaccine.

  10. Turning goals into results: the power of catalytic mechanisms.

    Science.gov (United States)

    Collins, J

    1999-01-01

    Most executives have a big, hairy, audacious goal. They write vision statements, formalize procedures, and develop complicated incentive programs--all in pursuit of that goal. In other words, with the best of intentions, they install layers of stultifying bureaucracy. But it doesn't have to be that way. In this article, Jim Collins introduces the catalytic mechanism, a simple yet powerful managerial tool that helps translate lofty aspirations into concrete reality. Catalytic mechanisms are the crucial link between objectives and performance; they are a galvanizing, nonbureaucratic means to turn one into the other. What's the difference between catalytic mechanisms and most traditional managerial controls? Catalytic mechanisms share five characteristics. First, they produce desired results in unpredictable ways. Second, they distribute power for the benefit of the overall system, often to the discomfort of those who traditionally hold power. Third, catalytic mechanisms have teeth. Fourth, they eject "viruses"--those people who don't share the company's core values. Finally, they produce an ongoing effect. Catalytic mechanisms are just as effective for reaching individual goals as they are for corporate ones. To illustrate how catalytic mechanisms work, the author draws on examples of individuals and organizations that have relied on such mechanisms to achieve their goals. The same catalytic mechanism that works in one organization, however, will not necessarily work in another. Catalytic mechanisms must be tailored to specific goals and situations. To help readers get started, the author offers some general principles that support the process of building catalytic mechanisms effectively. PMID:10539210

  11. Characterization of the functional role of a flexible loop in the alpha-subunit of tryptophan synthase from Salmonella typhimurium by rapid-scanning, stopped-flow spectroscopy and site-directed mutagenesis.

    Science.gov (United States)

    Brzović, P S; Hyde, C C; Miles, E W; Dunn, M F

    1993-10-01

    , produced from the cleavage of IGP, within the confines of the bienzyme complex. This conformational transition would promote the diffusion of indole to the beta-active site via the interconnecting tunnel and would help ensure the close coordination of alpha- and beta-subunit catalytic activities. PMID:8399184

  12. [Chromatographic and spectroscopic characterization of phycocyanin and its subunits purified from Anabaena variabilis CCC421].

    Science.gov (United States)

    Chakdar, N; Sakha, S; Pabbi, S

    2014-01-01

    Phycocyanin, a high value pigment was purified from diazotrophic cyanobacteria Anabaena variabilis CCC421 using a strategy involving ammonium sulfate precipitation, dialysis and anion exchange chromatography using DEAE-cellulose column. 36% phycocyanin with a purity of 2.75 was recovered finally after anion exchange chromatography. Purified phycocyanin was found to contain 2 subunits of 17 and 18 kDa which were identified as a-and (3 subunits by SDS-PAGE and MALDI-TOE HPLC method using a C5 column coupled with fluorescence or photodiode-based detection was also developed to separate and detect the A. variabilis CCC421 phycocyanin subunits. The fluorescence method was more sensitive than photodiode one. The purified phycocyanin from A. variabilis CCC421 as well as its subunits was characterized with respect to absorption and IR spectra. Spectral characterization of the subunits revealed that alpha and beta subunits contained one and two phycocyanobilin groups as chromophores, respectively. PMID:25272755

  13. Heterogeneous catalytic materials solid state chemistry, surface chemistry and catalytic behaviour

    CERN Document Server

    Busca, Guido

    2014-01-01

    Heterogeneous Catalytic Materials discusses experimental methods and the latest developments in three areas of research: heterogeneous catalysis; surface chemistry; and the chemistry of catalysts. Catalytic materials are those solids that allow the chemical reaction to occur efficiently and cost-effectively. This book provides you with all necessary information to synthesize, characterize, and relate the properties of a catalyst to its behavior, enabling you to select the appropriate catalyst for the process and reactor system. Oxides (used both as catalysts and as supports for cata

  14. Beta-Subunit of Human Chorionic Gonadotropin in Malignant Lymphoma : An Immunohistochemical Study

    OpenAIRE

    Senba, Masachika; Watanabe, Masami

    1991-01-01

    We present a rare case of a 77-year-old Japanese man with malignant lymphoma associated with production of beta-subunit of human chorionic gonadotropin in the cytoplasms of lymphoma cells in the lymph nodes. By immunoperoxidase staining, numerous tumor cells were reacted with beta-subunit of human chorionic gonadotropin. To the best of our knowledge, production of beta-subunit of human chorionic gonadotropin in the cytoplasm of lymphoma cells has not been reported. This patient evidences that...

  15. The NH2-terminal php domain of the alpha subunit of the Escherichia coli replicase binds the epsilon proofreading subunit.

    Science.gov (United States)

    Wieczorek, Anna; McHenry, Charles S

    2006-05-01

    The alpha subunit of the replicase of all bacteria contains a php domain, initially identified by its similarity to histidinol phosphatase but of otherwise unknown function (Aravind, L., and Koonin, E. V. (1998) Nucleic Acids Res. 26, 3746-3752). Deletion of 60 residues from the NH2 terminus of the alpha php domain destroys epsilon binding. The minimal 255-residue php domain, estimated by sequence alignment with homolog YcdX, is insufficient for epsilon binding. However, a 320-residue segment including sequences that immediately precede the polymerase domain binds epsilon with the same affinity as the 1160-residue full-length alpha subunit. A subset of mutations of a conserved acidic residue (Asp43 in Escherichia coli alpha) present in the php domain of all bacterial replicases resulted in defects in epsilon binding. Using sequence alignments, we show that the prototypical gram+ Pol C, which contains the polymerase and proofreading activities within the same polypeptide chain, has an epsilon-like sequence inserted in a surface loop near the center of the homologous YcdX protein. These findings suggest that the php domain serves as a platform to enable coordination of proofreading and polymerase activities during chromosomal replication.

  16. Expressões da homossexualidade feminina no encarceramento: o significado de se "transformar em homem" na prisão Expresiones de la homosexualidad femenina en el encarcelamiento: el significado de "transformarse en hombre" en la cárcel Expressions of female homosexuality in prison: the meaning of "becoming a man" during incarceration

    Directory of Open Access Journals (Sweden)

    Mariana Barcinski

    2012-12-01

    Full Text Available Mediante uma perspectiva de gênero, o presente trabalho tem como objetivo investigar as especificidades da homossexualidade feminina no encarceramento. Pela análise do discurso de entrevistas realizadas com duas mulheres encarceradas em uma unidade prisional feminina, trataremos dos significados atrelados ao "se transformar em homem" na prisão. As duas entrevistadas assumiram, dentro do cárcere, posturas, nomes e aparência masculinas e passaram, desde então, a ser reconhecidas por outras internas e pelo próprio staff do presídio como homens. O objetivo é entender que tipos de privilégios tais mulheres adquirem como resultado da adoção de padrões de comportamentos tipicamente masculinos. Os resultados atestam que as duas participantes experimentam o status e os direitos usualmente associados ao masculino, tais como a poligamia e o uso legitimado da força, reproduzindo no espaço intramuros a organização hierárquica que marca as relações heterossexuais na sociedade mais ampla.A través de una perspectiva de género, el presente estudio tiene como objetivo investigar las especificidades de la homosexualidad femenina en el encarcelamiento. Por medio del análisis del discurso de entrevistas realizadas con dos mujeres encarceladas en una unidad carcelaria femenina, trataremos de los significados vinculados al "transformarse en hombre" en la cárcel. Las dos entrevistadas asumieron, dentro de la cárcel, posturas, nombres y apariencia masculinos y pasaron, a partir de ahí, a seren reconocidas por otras internas y por propio staff de la cárcel como hombres. El objetivo es entender que tipos de privilegios esas mujeres adquieren como resultado de la adopción de patrones de comportamientos típicamente masculinos. Los resultados muestran que las dos participantes experimentan el status y los derechos usualmente asociados al masculino, tales y como la poligamia y el uso legitimado de la fuerza, reproduciendo en el espacio intramuros

  17. Composition and Content of High-Molecular-Weight Glutenin Subunits and Their Effects on Wheat Quality

    Institute of Scientific and Technical Information of China (English)

    SONG Jian-min; LIU Ai-feng; WU Xiang-yun; LIU Jian-jun; ZHAO Zhen-dong; LIU Guang-tian

    2002-01-01

    Sedimentation values, flour glutenin macropolymer (GMP) contents, composition and contents of high-molecular-weight (HMW) glutenin subunits (GS) of 233 flour samples were determined. Our data indicated that subunit 1 occurred more frequently at Glu-A1, subunit pair 7 + 8 at Glu- B1 and 2 + 12 at Glu-D1. The significant relationships between Glu-1 quality score and total HMW glutenin content, sedimentation value and GMP content suggested that the composition of HMW-GS affects wheat quality strongly. Moreover,the total content of HMW-GS was correlated with certain quality parameters more significantly. Relationship between subunit 5 + 10 content and breadmaking quality was better than others, but 2 + 12, 7 + 8, 7 + 9 and 4 + 12 also correlated with certain quality parameters significantly. The contents of total HMW-glutenin, x-type subunits and y-type subunits related with sedimentation value, flour GMP content, and Glu-1 quality score more strongly than that of individual subunit or subunit pair. The flour GMP content, with excellent correlation to sedimentation value, total contents of HMW glutenin, x- and y-type subunits and many other quality parameters, could be an ideal indicator of breadmaking quality at earlier generations for breeding purpose for its simple procedure and small scale.

  18. Subunit Characteristics of Pig Pancreas Ferritin Revealed by MALDI-TOF MS and RP-HPLC

    Institute of Scientific and Technical Information of China (English)

    HUANG Lin; LIN Zhi-cao; LIN Qing; LUO Lian-zhong; HUANG He-qing

    2008-01-01

    Pig pancreas ferritin(PPF) was purified by ultra-centrifugation,ion-exchange chromatography,and native gradient polyacrylamide gel electrophoresis(PAGENG).Sodium dodecyl sulfate(SDS)-PAGE indicates that PPF consists of two subunit types,namely,H(21000) and L(19000) subunits,and its core shows an average element composition of 1698 Fe3+ and 179 phosphate molecules within the hollow shell,giving a 9.5:1 ratio of Fe3+ to phosphate.An off line approach combining reversed-phase high-performance liquid chromatography(RP-HPLC) with matrix-assisted laser desorption ionization time of flight mass speetrometry(MALDI-TOF MS) made the decomposition of PPF shell into H and L subunits for the analysis of mass spectrometry(MS),giving molecular weights of both H(21014.4) and L(18319.9)subunits.Both subunit types were further identified by an approach combining peptide mass fingerprint(PMF) with database search.A ratio of IH to 2L subunits in PPF was determined by SDS-PAGE,RP-HPLC,and MALDI-TOF MS,respectively.It is well known that the non-covalent interaction of L-L or H-L subunits is stronger than that of H-H subunits in PPF,which may be further used to explain the unclear physiological function between H and L subunits in PPF.

  19. Genetic Diversity of High and Low Molecular Weight Glutenin Subunits in Algerian Aegilops geniculata

    Directory of Open Access Journals (Sweden)

    Asma MEDOURI

    2014-12-01

    Full Text Available Aegilops geniculata Roth is an annual grass relative to cultivated wheat and is widely distributed in North Algeria. Endosperm storage proteins of wheat and its relatives, namely glutenins and gliadins, play an important role in dough properties and bread making quality. In the present study, the different alleles encoded at the four glutenin loci (Glu-M1, Glu-U1, Glu-M3 and Glu-U3 were identified from thirty five accessions of the tetraploid wild wheat A. geniculata collected in Algeria using Sodium dodecyl Sulfate - Polyacrylamide Gel Electrophoresis (SDS-PAGE. At Glu-M1 and Glu-U1 loci, encoding high molecular weight glutenin subunits (HMW-GS or A-subunits, 15 and 12 alleles were observed respectively, including one new subunit. B-Low molecular weight glutenin subunits zone (B-LMW-GS displayed a far greater variation, as 28 and 25 alleles were identified at loci Glu-M3 and Glu-U3 respectively. Thirty two subunits patterns were revealed at the C subunits- zone and a total of thirty four patterns resulted from the genetic combination of the two zones (B- and C-zone. The wide range of glutenin subunits variation (high molecular weight glutenin subunits and low molecular weight glutenin subunits in this species has the potential to enhance the genetic variability for improving the quality of wheat./span>

  20. Structure–Function Relationships in Fungal Large-Subunit Catalases

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, A.; Valdez, V; Rudino-Pinera, E; Horjales, E; Hansberg, W

    2009-01-01

    Neurospora crassa has two large-subunit catalases, CAT-1 and CAT-3. CAT-1 is associated with non-growing cells and accumulates particularly in asexual spores; CAT-3 is associated with growing cells and is induced under different stress conditions. It is our interest to elucidate the structure-function relationships in large-subunit catalases. Here we have determined the CAT-3 crystal structure and compared it with the previously determined CAT-1 structure. Similar to CAT-1, CAT-3 hydrogen peroxide (H{sub 2}O{sub 2}) saturation kinetics exhibited two components, consistent with the existence of two active sites: one saturated in the millimolar range and the other in the molar range. In the CAT-1 structure, we found three interesting features related to its unusual kinetics: (a) a constriction in the channel that conveys H{sub 2}O{sub 2} to the active site; (b) a covalent bond between the tyrosine, which forms the fifth coordination bound to the iron of the heme, and a vicinal cysteine; (c) oxidation of the pyrrole ring III to form a cis-hydroxyl group in C5 and a cis-{gamma}-spirolactone in C6. The site of heme oxidation marks the starts of the central channel that communicates to the central cavity and the shortest way products can exit the active site. CAT-3 has a similar constriction in its major channel, which could function as a gating system regulated by the H{sub 2}O{sub 2} concentration before the gate. CAT-3 functional tyrosine is not covalently bonded, but has instead the electron relay mechanism described for the human catalase to divert electrons from it. Pyrrole ring III in CAT-3 is not oxidized as it is in other large-subunit catalases whose structure has been determined. Different in CAT-3 from these enzymes is an occupied central cavity. Results presented here indicate that CAT-3 and CAT-1 enzymes represent a functional group of catalases with distinctive structural characteristics that determine similar kinetics.

  1. Des prisons médiatiques et des prisonniers: l´institution carcérale et la pénalité face aux évolutions de l´espace public = Sobre prisões midiáticas e prisioneiros: a instituição carcerária e a punição diante das evoluções do espaço público

    Directory of Open Access Journals (Sweden)

    Ricordeau, Gwenola

    2009-01-01

    Full Text Available O artigo enfoca as relações entre o espaço público, os prisioneiros e a instituição carcerária, onde se negocia continuamente as fronteiras do público/privado. A qualificação da prisão como uma "instituição total" é cada vez mais discutido, uma vez que sua crescente abertura ao exterior e processo de democratização permite aos prisioneiros o acesso à informação global e até mesmo a sua liberdade de expressão. Mas os encarcerados, assim como seus familiares, estão excluídos dos debates recorrentes sobre a necessária reforma prisional. A normalização das condições de detenção faz as sentenças se parecerem jogos (tipo "reality-show", em que o dentro é cada vez mais difícil de se distinguir do fora, invadido pelo monitoramento de vídeo e fenômenos virtuais. As evoluções das penas se traduzem por uma revolução do e no espaço privado do condenado

  2. Catalytic bioscavengers in nerve agent poisoning: A promising approach?

    Science.gov (United States)

    Worek, Franz; Thiermann, Horst; Wille, Timo

    2016-02-26

    The repeated use of the nerve agent sarin against civilians in Syria in 2013 emphasizes the continuing threat by chemical warfare agents. Multiple studies demonstrated a limited efficacy of standard atropine-oxime treatment in nerve agent poisoning and called for the development of alternative and more effective treatment strategies. A novel approach is the use of stoichiometric or catalytic bioscavengers for detoxification of nerve agents in the systemic circulation prior to distribution into target tissues. Recent progress in the design of enzyme mutants with reversed stereo selectivity resulting in improved catalytic activity and their use in in vivo studies supports the concept of catalytic bioscavengers. Yet, further research is necessary to improve the catalytic activity, substrate spectrum and in vivo biological stability of enzyme mutants. The pros and cons of catalytic bioscavengers will be discussed in detail and future requirements for the development of catalytic bioscavengers will be proposed.

  3. Engineering Metallic Nanoparticles for Enhancing and Probing Catalytic Reactions.

    Science.gov (United States)

    Collins, Gillian; Holmes, Justin D

    2016-07-01

    Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs. PMID:26823380

  4. Fluid catalytic cracking of biomass pyrolysis vapors

    Energy Technology Data Exchange (ETDEWEB)

    Mante, Ofei Daku [Virginia Polytechnic Institute and State University, Biological Systems Engineering, Blacksburg, VA (United States); Agblevor, Foster A. [Utah State University, Biological Engineering, Logan, UT (United States); McClung, Ron [BASF Inc, Florham, NJ (United States)

    2011-12-15

    Catalytic cracking of pyrolysis oils/vapors offers the opportunity of producing bio-oils which can potentially be coprocessed with petroleum feedstocks in today's oil refinery to produce transportation fuel and chemicals. Catalyst properties and process conditions are critical in producing and maximizing desired product. In our studies, catalyst matrix (kaolin) and two commercial fluid catalytic cracking (FCC) catalysts, FCC-H and FCC-L, with different Y-zeolite contents were investigated. The catalytic cracking of hybrid poplar wood was conducted in a 50-mm bench-scale bubbling fluidized-bed pyrolysis reactor at 465 C with a weight hourly space velocity of 1.5 h{sup -1}. The results showed that the yields and quality of the bio-oils was a function of the Y-zeolite content of the catalyst. The char/coke yield was highest for the higher Y-zeolite catalyst. The organic liquid yields decreased inversely with increase in zeolite content of the catalyst whereas the water and gas yields increased. Analysis of the oils by both Fourier-transform infrared and {sup 13}C-nuclear magnetic resonance indicated that the catalyst with higher zeolite content (FCC-H) was efficient in the removal of compounds like levoglucosan, carboxylic acids and the conversion of methoxylated phenols to substituted phenols and benzenediols. The cracking of pyrolysis products by kaolin suggests that the activity of the FCC catalyst on biomass pyrolysis vapors can be attributed to both Y-zeolite and matrix. The FCC-H catalyst produced much more improved oil. The oil was low in oxygen (22.67 wt.%), high in energy (29.79 MJ/kg) and relatively stable over a 12-month storage period. (orig.)

  5. Catalytic Mechanism of Human Alpha-galactosidase

    Energy Technology Data Exchange (ETDEWEB)

    Guce, A.; Clark, N; Salgado, E; Ivanen, D; Kulinskaya, A; Brumer, H; Garman, S

    2010-01-01

    The enzyme {alpha}-galactosidase ({alpha}-GAL, also known as {alpha}-GAL A; E.C. 3.2.1.22) is responsible for the breakdown of {alpha}-galactosides in the lysosome. Defects in human {alpha}-GAL lead to the development of Fabry disease, a lysosomal storage disorder characterized by the buildup of {alpha}-galactosylated substrates in the tissues. {alpha}-GAL is an active target of clinical research: there are currently two treatment options for Fabry disease, recombinant enzyme replacement therapy (approved in the United States in 2003) and pharmacological chaperone therapy (currently in clinical trials). Previously, we have reported the structure of human {alpha}-GAL, which revealed the overall structure of the enzyme and established the locations of hundreds of mutations that lead to the development of Fabry disease. Here, we describe the catalytic mechanism of the enzyme derived from x-ray crystal structures of each of the four stages of the double displacement reaction mechanism. Use of a difluoro-{alpha}-galactopyranoside allowed trapping of a covalent intermediate. The ensemble of structures reveals distortion of the ligand into a {sup 1}S{sub 3} skew (or twist) boat conformation in the middle of the reaction cycle. The high resolution structures of each step in the catalytic cycle will allow for improved drug design efforts on {alpha}-GAL and other glycoside hydrolase family 27 enzymes by developing ligands that specifically target different states of the catalytic cycle. Additionally, the structures revealed a second ligand-binding site suitable for targeting by novel pharmacological chaperones.

  6. A method for controlling catalytic reforming

    Energy Technology Data Exchange (ETDEWEB)

    Karamyshev, M.S.; Denilov, N.A.; Kamyshnikov, A.I.; Kirilin, Yu.A.; Lozinskiy, V.N.; Melman, A.Z.; Ovchinnikova, T.F.; Shpunt, M.I.; Shuvalov, V.V.; Zayashnikov, Ye.N.

    1983-01-01

    In the method for controlling the process of catalytic reforming, which includes mixing the raw material components with the production of a raw material, reforming and isolation of the final products, through changing the relationship of the expenditures of the raw material components relative to the content of the target components in the raw material, in order to support and stabilize an assigned production of the final products, the relationship of the expenditures of the raw material components are changed with correction based on the flow rates of the final products. A block diagram of the installation which realizes the proposed method is cited.

  7. Transport in a Microfluidic Catalytic Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, H G; Chung, J; Grigoropoulos, C P; Greif, R; Havstad, M; Morse, J D

    2003-04-30

    A study of the heat and mass transfer, flow, and thermodynamics of the reacting flow in a catalytic microreactor is presented. Methanol reforming is utilized in the fuel processing system driving a micro-scale proton exchange membrane fuel cell. Understanding the flow and thermal transport phenomena as well as the reaction mechanisms is essential for improving the efficiency of the reforming process as well as the quality of the processed fuel. Numerical studies have been carried out to characterize the transport in a silicon microfabricated reactor system. On the basis of these results, optimized conditions for fuel processing are determined.

  8. Submicron Polyethylene Particles from Catalytic Emulsion Polymerization

    OpenAIRE

    Bauers, Florian Martin; Thomann, Ralf; Mecking, Stefan

    2003-01-01

    Particles of linear polyethylene (Mn = (2-3)X 10000 g mol-1; Mw/Mn = 2-4) obtained by catalytic emulsion polymerization of ethylene possess a nonspherical, lentil-like shape with an average aspect ratio of ca. 10 and diameters from 30 to > 300 nm, as determined by TEM and AFM. The particle structure results from a stacking of the lamellae along the one shorter axis of the lentils (i.e., their height, by contrast to the diameter). In addition to these multilamellae particles, remarkably, a con...

  9. Temperature control of a catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Ma, T.T.-H.

    1994-06-08

    In an ic engine having a catalytic convertor, the catalyst heater is controlled in dependence upon an estimate of the temperature of the catalyst so that there is no need for a sensor in the hostile environment of the exhaust. A valve indicative of the catalyst temperature is stored and modified in accordance with a model of the catalyst temperature. The model can be a mathematical mood carried out by a signal processor or an electrical model with the catalyst temperature being represented by the charge stored on a capacitor. (Author)

  10. Biomimetic, Catalytic Oxidation in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Shun-lchi Murahashi

    2005-01-01

    @@ 1Introduction Oxidation is one of the most fundamental reactions in organic synthesis. Owing to the current need to develop forward-looking technology that is environmentally acceptable with respect many aspects. The most attractive approaches are biomimetic oxidation reactions that are closely related to the metabolism of living things. The metabolisms are governed by a variety of enzymes such as cytochrome P-450 and flavoenzyme.Simulation of the function of these enzymes with simple transition metal complex catalyst or organic catalysts led to the discovery of biomimetic, catalytic oxidations with peroxides[1]. We extended such biomimetic methods to the oxidation with molecular oxygen under mild conditions.

  11. Catalytic Pyrolysis of Olive Mill Wastewater Sludge

    OpenAIRE

    Abdellaoui, Hamza

    2015-01-01

    Olive mill wastewater sludge (OMWS) is the solid residue that remains in the evaporation ponds after evaporation of the majority of water in the olive mill wastewater (OMW). OMWS is a major environmental pollutant in the olive oil producing regions. Approximately 41.16 wt. % of the OMWS was soluble in hexanes (HSF). The fatty acids in this fraction consist mainly of oleic and palmitic acid. Catalytic pyrolysis of the OMWS over red mud and HZSM-5 has been demonstrated to be an effective techno...

  12. Tritium stripping by a catalytic exchange stripper

    International Nuclear Information System (INIS)

    A catalytic exchange process for stripping elemental tritium from gas streams has been demonstrated. The process uses a catalyzed isotopic exchange reaction between tritium in the gas phase and protium or deuterium in the solid phase on alumina. The reaction is catalyzed by platinum deposited on the alumina. The process has been tested with both tritium and deuterium. Decontamination factors (ration of inlet and outlet tritium concentrations) as high as 1000 have been achieved, depending on inlet concentration. The test results and some demonstrated applications are presented

  13. Heterogeneous Photooxidation of Phenol by Catalytic Membranes

    Institute of Scientific and Technical Information of China (English)

    Enrica Fontananova; Enrico Drioli; Laura Donato; Marcella Bonchio; Mauro Carraro; Gianfranco Scorrano

    2006-01-01

    In this work the heterogenization in polymeric membranes of decatungstate, a photocatalyst for oxidation reactions,was reported. Solid state characterization techniques confirmed that the catalyst structure was preserved within the polymeric membranes. The catalytic membranes were successfully applied in the aerobic photo-oxidation of phenol, one of the main organic pollutants in wastewater, providing stable and recyclable photocatalytic systems. The dependence of the phenol degradation rate by the catalyst loading and transmembrane pressure was shown. By comparison with homogeneous reaction,the catalyst heterogenized in membrane appears to be more efficient concerning the rate of phenol photodegradation and mineralization.

  14. Catalytic Synthesis Methods for Triazolopyrimidine Derivatives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new method for catalyzed synthesis of triazolopyrimidine derivatives is reported. Aikylamine reaction with dialkyl cyanodithioiminocarbonate was catalyzed by quaternary ammonium salts at room temperature to yield 3-alkylamine-5-amino-1,2,4-triazole in good quality and high yields. After imidization and reaction with an α,β-unsaturated acid derivative, the reaction intermediate was hydrolyzed in the presence of a Lewis acid to obtain the target product. This novel catalytic method for triazolopyrimidine derivatives can be carried out under inexpen-sive and mild conditions, and is safe and environmentally friendly. IH NMR results for all intermediates are re-ported.

  15. The catalytic residues of Tn3 resolvase

    OpenAIRE

    Olorunniji, F.J.; Stark, W M

    2009-01-01

    To characterize the residues that participate in the catalysis of DNA cleavage and rejoining by the site-specific recombinase Tn3 resolvase, we mutated conserved polar or charged residues in the catalytic domain of an activated resolvase variant. We analysed the effects of mutations at 14 residues on proficiency in binding to the recombination site ('site I'), formation of a synaptic complex between two site Is, DNA cleavage and recombination. Mutations of Y6, R8, S10, D36, R68 and R71 result...

  16. Study and Analysis on Naphtha Catalytic Reforming Reactor Simulation

    Institute of Scientific and Technical Information of China (English)

    Liang Ke min; Song Yongji; Pan Shiwei

    2004-01-01

    A naphtha catalytic reforming unit with four reactors connected in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reaction characteristics based on idealizing the complex naphtha mixture to represent the paraffin, naphthene, and aromatic groups with individual compounds. The simulation results based on above models agree very well with actual operating data of process unit.

  17. A study on naphtha catalytic reforming reactor simulation and analysis

    Institute of Scientific and Technical Information of China (English)

    LIANG Ke-min; GUO Hai-yan; PAN Shi-wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  18. Structure of the iSH2 domain of Human phosphatidylinositol 3-kinase p85 beta Subunit Reveals Conformational Plasticity in the Interhelical Turn Region

    Energy Technology Data Exchange (ETDEWEB)

    C Schauder; L Ma; R Krug; G Montelione; R Guan

    2011-12-31

    Phosphatidylinositol 3-kinase (PI3K) proteins actively trigger signaling pathways leading to cell growth, proliferation and survival. These proteins have multiple isoforms and consist of a catalytic p110 subunit and a regulatory p85 subunit. The iSH2 domain of the p85 {beta} isoform has been implicated in the binding of nonstructural protein 1 (NS1) of influenza A viruses. Here, the crystal structure of human p85 {beta} iSH2 determined to 3.3 {angstrom} resolution is reported. The structure reveals that this domain mainly consists of a coiled-coil motif. Comparison with the published structure of the bovine p85 {beta} iSH2 domain bound to the influenza A virus nonstructural protein 1 indicates that little or no structural change occurs upon complex formation. By comparing this human p85 {beta} iSH2 structure with the bovine p85 {beta} iSH2 domain, which shares 99% sequence identity, and by comparing the multiple conformations observed within the asymmetric unit of the bovine iSH2 structure, it was found that this coiled-coil domain exhibits a certain degree of conformational variability or 'plasticity' in the interhelical turn region. It is speculated that this plasticity of p85 {beta} iSH2 may play a role in regulating its functional and molecular-recognition properties.

  19. Proteomic analysis of human norepinephrine transporter complexes reveals associations with protein phosphatase 2A anchoring subunit and 14-3-3 proteins

    International Nuclear Information System (INIS)

    The norepinephrine transporter (NET) terminates noradrenergic signals by clearing released NE at synapses. NET regulation by receptors and intracellular signaling pathways is supported by a growing list of associated proteins including syntaxin1A, protein phosphatase 2A (PP2A) catalytic subunit (PP2A-C), PICK1, and Hic-5. In the present study, we sought evidence for additional partnerships by mass spectrometry-based analysis of proteins co-immunoprecipitated with human NET (hNET) stably expressed in a mouse noradrenergic neuroblastoma cell line. Our initial proteomic analyses reveal multiple peptides derived from hNET, peptides arising from the mouse PP2A anchoring subunit (PP2A-Ar) and peptides derived from 14-3-3 proteins. We verified physical association of NET with PP2A-Ar via co-immunoprecipitation studies using mouse vas deferens extracts and with 14-3-3 via a fusion pull-down approach, implicating specifically the hNET NH2-terminus for interactions. The transporter complexes described likely support mechanisms regulating transporter activity, localization, and trafficking

  20. Crystal structure of the two-subunit tRNA m1A58 methyltransferase TRM6-TRM61 from Saccharomyces cerevisiae

    Science.gov (United States)

    Wang, Mingxing; Zhu, Yuwei; Wang, Chongyuan; Fan, Xiaojiao; Jiang, Xuguang; Ebrahimi, Mohammad; Qiao, Zhi; Niu, Liwen; Teng, Maikun; Li, Xu

    2016-01-01

    The N1 methylation of adenine at position 58 (m1A58) of tRNA is an important post-transcriptional modification, which is vital for maintaining the stability of the initiator methionine tRNAiMet. In eukaryotes, this modification is performed by the TRM6-TRM61 holoenzyme. To understand the molecular mechanism that underlies the cooperation of TRM6 and TRM61 in the methyl transfer reaction, we determined the crystal structure of TRM6-TRM61 holoenzyme from Saccharomyces cerevisiae in the presence and absence of its methyl donor S-Adenosyl-L-methionine (SAM). In the structures, two TRM6-TRM61 heterodimers assemble as a heterotetramer. Both TRM6 and TRM61 subunits comprise an N-terminal β-barrel domain linked to a C-terminal Rossmann-fold domain. TRM61 functions as the catalytic subunit, containing a methyl donor (SAM) binding pocket. TRM6 diverges from TRM61, lacking the conserved motifs used for binding SAM. However, TRM6 cooperates with TRM61 forming an L-shaped tRNA binding regions. Collectively, our results provide a structural basis for better understanding the m1A58 modification of tRNA occurred in Saccharomyces cerevisiae. PMID:27582183

  1. Involvement of β3A Subunit of Adaptor Protein-3 in Intracellular Trafficking of Receptor-like Protein Tyrosine Phosphatase PCP-2

    Institute of Scientific and Technical Information of China (English)

    Hui DONG; Hong YUAN; Weirong JIN; Yan SHEN; Xiaojing XU; Hongyang WANG

    2007-01-01

    PCP-2 is a human receptor-like protein tyrosine phosphatase and a member of the MAM domain family cloned in human pancreatic adenocarcinoma cells. Previous studies showed that PCP-2 directly interacted with β-catenin through the juxtamembrane domain, dephosphorylated β-catenin and played an important role in the regulation of cell adhesion. Recent study showed that PCP-2 was also involved in the repression of β-catenin-induced transcriptional activity. Here we describe the interactions of PCP-2 with the β3A subunit of adaptor protein (AP)-3 and sorting nexin (SNX) 3. These protein complexes were detected using the yeast two-hybrid assay with the juxtamembrane and membrane-proximal catalytic domain of PCP-2 as "bait". Both AP-3 and SNX3 are molecules involved in intracellular trafficking of membrane receptors. The association between the β3A subunit of AP-3 and PCP-2 was further confirmed in mammalian cells. Our results suggested a possible mechanism of intracellular trafficking of PCP-2 mediated by AP-3 and SNX3 which might participate in the regulation of PCP-2 functions.

  2. Glycine Receptor α2 Subunit Activation Promotes Cortical Interneuron Migration

    Directory of Open Access Journals (Sweden)

    Ariel Avila

    2013-08-01

    Full Text Available Glycine receptors (GlyRs are detected in the developing CNS before synaptogenesis, but their function remains elusive. This study demonstrates that functional GlyRs are expressed by embryonic cortical interneurons in vivo. Furthermore, genetic disruption of these receptors leads to interneuron migration defects. We discovered that extrasynaptic activation of GlyRs containing the α2 subunit in cortical interneurons by endogenous glycine activates voltage-gated calcium channels and promotes calcium influx, which further modulates actomyosin contractility to fine-tune nuclear translocation during migration. Taken together, our data highlight the molecular events triggered by GlyR α2 activation that control cortical tangential migration during embryogenesis.

  3. Chaperonin Structure - The Large Multi-Subunit Protein Complex

    Directory of Open Access Journals (Sweden)

    Irena Roterman

    2009-03-01

    Full Text Available The multi sub-unit protein structure representing the chaperonins group is analyzed with respect to its hydrophobicity distribution. The proteins of this group assist protein folding supported by ATP. The specific axial symmetry GroEL structure (two rings of seven units stacked back to back - 524 aa each and the GroES (single ring of seven units - 97 aa each polypeptide chains are analyzed using the hydrophobicity distribution expressed as excess/deficiency all over the molecule to search for structure-to-function relationships. The empirically observed distribution of hydrophobic residues is confronted with the theoretical one representing the idealized hydrophobic core with hydrophilic residues exposure on the surface. The observed discrepancy between these two distributions seems to be aim-oriented, determining the structure-to-function relation. The hydrophobic force field structure generated by the chaperonin capsule is presented. Its possible influence on substrate folding is suggested.

  4. Non-thermal plasmas for non-catalytic and catalytic VOC abatement

    International Nuclear Information System (INIS)

    Highlights: → We review the current status of catalytic and non-catalytic VOC abatement based on a vast number of research papers. → The underlying mechanisms of plasma-catalysis for VOC abatement are discussed. → Critical process parameters that determine the influent are discussed and compared. - Abstract: This paper reviews recent achievements and the current status of non-thermal plasma (NTP) technology for the abatement of volatile organic compounds (VOCs). Many reactor configurations have been developed to generate a NTP at atmospheric pressure. Therefore in this review article, the principles of generating NTPs are outlined. Further on, this paper is divided in two equally important parts: plasma-alone and plasma-catalytic systems. Combination of NTP with heterogeneous catalysis has attracted increased attention in order to overcome the weaknesses of plasma-alone systems. An overview is given of the present understanding of the mechanisms involved in plasma-catalytic processes. In both parts (plasma-alone systems and plasma-catalysis), literature on the abatement of VOCs is reviewed in close detail. Special attention is given to the influence of critical process parameters on the removal process.

  5. Effective polymer adjuvants for sustained delivery of protein subunit vaccines.

    Science.gov (United States)

    Adams, Justin R; Haughney, Shannon L; Mallapragada, Surya K

    2015-03-01

    We have synthesized thermogelling cationic amphiphilic pentablock copolymers that have the potential to act as injectable vaccine carriers and adjuvants that can simultaneously provide sustained delivery and enhance the immunogenicity of released antigen. While these pentablock copolymers have shown efficacy in DNA delivery in past studies, the ability to deliver both DNA and protein for subunit vaccines using the same polymeric carrier can provide greater flexibility and efficacy. We demonstrate the ability of these pentablock copolymers, and the parent triblock Pluronic copolymers to slowly release structurally intact and antigenically stable protein antigens in vitro, create an antigen depot through long-term injection-site persistence and enhance the in vivo immune response to these antigens. We show release of the model protein antigen ovalbumin in vitro from the thermogelling block copolymers with the primary, secondary and tertiary structures of the released protein unchanged compared to the native protein, and its antigenicity preserved upon release. The block copolymers form a gel at physiological temperatures that serves as an antigenic depot and persists in vivo at the site of injection for over 50days. The pentablock copolymers show a significant fivefold enhancement in the immune response compared to soluble protein alone, even 6weeks after the administration, based on measurement of antibody titers. These results demonstrate the potential of these block copolymers hydrogels to persist for several weeks and sustain the release of antigen with minimal effects on protein stability and antigenicity; and their ability to be used simultaneously as a sustained delivery device as well as a subunit vaccine adjuvant platform. PMID:25484331

  6. Formalin-inactivated whole virus and recombinant subunit flavivirus vaccines.

    Science.gov (United States)

    Eckels, Kenneth H; Putnak, Robert

    2003-01-01

    The Flaviviridae is a family of arthropod-borne, enveloped, RNA viruses that contain important human pathogens such as yellow fever (YF), Japanese encephalitis (JE), tick-borne encephalitis (TBE), West Nile (WN), and the dengue (DEN) viruses. Vaccination is the most effective means of disease prevention for these viral infections. A live-attenuated vaccine for YF, and inactivated vaccines for JE and TBE have significantly reduced the incidence of disease for these viruses, while licensed vaccines for DEN and WN are still lacking despite a significant disease burden associated with these infections. This review focuses on inactivated and recombinant subunit vaccines (non-replicating protein vaccines) in various stages of laboratory development and human testing. A purified, inactivated vaccine (PIV) candidate for DEN will soon be evaluated in a phase 1 clinical trial, and a second-generation JE PIV produced using similar technology has advanced to phase 2/3 trials. The inactivated TBE vaccine used successfully in Europe for almost 30 years continues to be improved by additional purification, new stabilizers, an adjuvant, and better immunization schedules. The recent development of an inactivated WN vaccine for domestic animals demonstrates the possibility of producing a similar vaccine for human use. Advances in flavivirus gene expression technology have led to the production of several recombinant subunit antigen vaccine candidates in a variety of expression systems. Some of these vaccines have shown sufficient promise in animal models to be considered as candidates for evaluation in clinical trials. Feasibility of non-replicating flavivirus vaccines has been clearly demonstrated and further development is now warranted. PMID:14714438

  7. Proteomic analysis of transducin beta-subunit structural heterogeneity.

    Science.gov (United States)

    Clack, James W; Juhl, Martha; Rice, Carol A; Li, Junyu; Witzmann, Frank A

    2003-10-01

    Partially purified transducin was resolved using two-dimensional gel electrophoresis (2-DE). Peptide mass fingerprinting of several different spots believed to correspond to the 37 kDa beta-subunit of transducin (T(beta)) was performed. Spots were excised and proteolyzed using modified trypsin. Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was performed on the peptide mixture resulting from each spot. As many as six spots with different pI, ranging from 5.2 to 6.1, were observed when separated using 2-DE. MALDI peptide mass fingerprinting determined with high probability that all of the spots were the same gene product, guanine nucleotide-binding protein G(I)/G(S)/G(T) beta-subunit 1 (GNB1; T(beta1)). This suggested that post-translational modification was responsible for the differences in pI. Phosphorylation experiments showed that at least one T(beta1) spot was phosphorylated in vitro with [gamma-(32)P]ATP by an endogenous kinase. Treatment of T(beta) with alkaline phosphatase caused a large change in the spot pattern of T(beta), suggesting that phosphorylated T(beta) is a substrate for alkaline phosphatase. We conclude that T(beta1) constitutes over 99% of the T(beta) expressed in bovine rod outer segments and displays structural heterogeneity that is due to post-translational modification. We also conclude that some, but not all, of the heterogeneity observed is due to phosphorylation of Tb1. PMID:14595696

  8. Catalytically favorable surface patterns in Pt-Au nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb

    2013-01-01

    Motivated by recent experimental demonstrations of novel PtAu nanoparticles with highly enhanced catalytic properties, we present a systematic theoretical study that explores principal catalytic indicators as a function of the particle size and composition. We find that Pt electronic states in the vicinity of the Fermi level combined with a modified electron distribution in the nanoparticle due to Pt-to-Au charge transfer are the origin of the outstanding catalytic properties. From our model we deduce the catalytically favorable surface patterns that induce ensemble and ligand effects. © The Royal Society of Chemistry 2013.

  9. Aerobic Growth of Escherichia coli Is Reduced, and ATP Synthesis Is Selectively Inhibited when Five C-terminal Residues Are Deleted from the ϵ Subunit of ATP Synthase.

    Science.gov (United States)

    Shah, Naman B; Duncan, Thomas M

    2015-08-21

    F-type ATP synthases are rotary nanomotor enzymes involved in cellular energy metabolism in eukaryotes and eubacteria. The ATP synthase from Gram-positive and -negative model bacteria can be autoinhibited by the C-terminal domain of its ϵ subunit (ϵCTD), but the importance of ϵ inhibition in vivo is unclear. Functional rotation is thought to be blocked by insertion of the latter half of the ϵCTD into the central cavity of the catalytic complex (F1). In the inhibited state of the Escherichia coli enzyme, the final segment of ϵCTD is deeply buried but has few specific interactions with other subunits. This region of the ϵCTD is variable or absent in other bacteria that exhibit strong ϵ-inhibition in vitro. Here, genetically deleting the last five residues of the ϵCTD (ϵΔ5) caused a greater defect in respiratory growth than did the complete absence of the ϵCTD. Isolated membranes with ϵΔ5 generated proton-motive force by respiration as effectively as with wild-type ϵ but showed a nearly 3-fold decrease in ATP synthesis rate. In contrast, the ϵΔ5 truncation did not change the intrinsic rate of ATP hydrolysis with membranes. Further, the ϵΔ5 subunit retained high affinity for isolated F1 but reduced the maximal inhibition of F1-ATPase by ϵ from >90% to ∼20%. The results suggest that the ϵCTD has distinct regulatory interactions with F1 when rotary catalysis operates in opposite directions for the hydrolysis or synthesis of ATP.

  10. Inhibition of K+ Transport through Na+, K+-ATPase by Capsazepine: Role of Membrane Span 10 of the α-Subunit in the Modulation of Ion Gating

    Science.gov (United States)

    Mahmmoud, Yasser A.; Shattock, Michael; Cornelius, Flemming; Pavlovic, Davor

    2014-01-01

    Capsazepine (CPZ) inhibits Na+,K+-ATPase-mediated K+-dependent ATP hydrolysis with no effect on Na+-ATPase activity. In this study we have investigated the functional effects of CPZ on Na+,K+-ATPase in intact cells. We have also used well established biochemical and biophysical techniques to understand how CPZ modifies the catalytic subunit of Na+,K+-ATPase. In isolated rat cardiomyocytes, CPZ abolished Na+,K+-ATPase current in the presence of extracellular K+. In contrast, CPZ stimulated pump current in the absence of extracellular K+. Similar conclusions were attained using HEK293 cells loaded with the Na+ sensitive dye Asante NaTRIUM green. Proteolytic cleavage of pig kidney Na+,K+-ATPase indicated that CPZ stabilizes ion interaction with the K+ sites. The distal part of membrane span 10 (M10) of the α-subunit was exposed to trypsin cleavage in the presence of guanidinum ions, which function as Na+ congener at the Na+ specific site. This effect of guanidinium was amplified by treatment with CPZ. Fluorescence of the membrane potential sensitive dye, oxonol VI, was measured following addition of substrates to reconstituted inside-out Na+,K+-ATPase. CPZ increased oxonol VI fluorescence in the absence of K+, reflecting increased Na+ efflux through the pump. Surprisingly, CPZ induced an ATP-independent increase in fluorescence in the presence of high extravesicular K+, likely indicating opening of an intracellular pathway selective for K+. As revealed by the recent crystal structure of the E1.AlF4-.ADP.3Na+ form of the pig kidney Na+,K+-ATPase, movements of M5 of the α-subunit, which regulate ion selectivity, are controlled by the C-terminal tail that extends from M10. We propose that movements of M10 and its cytoplasmic extension is affected by CPZ, thereby regulating ion selectivity and transport through the K+ sites in Na+,K+-ATPase. PMID:24816799

  11. Abundant intergenic TAACTGA direct repeats and putative alternate RNA polymerase β´ subunits in marine Beggiatoaceae genomes: possible regulatory roles and origins

    Directory of Open Access Journals (Sweden)

    Barbara J. MacGregor

    2015-12-01

    Full Text Available The genome sequences of several giant marine sulfur-oxidizing bacteria present evidence of a possible post-transcriptional regulatory network that may have been transmitted to or from two distantly related bacteria lineages. The draft genome of a Cand. Maribeggiatoa filament from the Guaymas Basin (Gulf of California, Mexico seafloor contains 169 sets of TAACTGA direct repeats and one indirect repeat, with two to six copies per set. Related heptamers are rarely or never found as direct repeats. TAACTGA direct repeats are also found in some other Beggiatoaceae, Thiocystis violascens, a range of Cyanobacteria, and five Bacteroidetes. This phylogenetic distribution suggests they may have been transmitted horizontally, but no mechanism is evident. There is no correlation between total TAACTGA occurrences and repeats per genome. In most species the repeat units are relatively short, but longer arrays of up to 43 copies are found in several Bacteroidetes and Cyanobacteria. The majority of TAACTGA repeats in the Cand. Maribeggiatoa Orange Guaymas (BOGUAY genome are within several nucleotides upstream of a putative start codon, suggesting they may be binding sites for a post-transcriptional regulator. Candidates include members of the ribosomal protein S1, Csp (cold shock protein, and Csr (carbon storage regulator families. No pattern was evident in the predicted functions of the open reading frames (ORFs downstream of repeats, but some encode presumably essential products such as ribosomal proteins. Among these is an ORF encoding a possible alternate or modified RNA polymerase beta prime subunit, predicted to have the expected subunit interaction domains but lacking most catalytic residues. A similar ORF was found in the Thioploca ingrica draft genome, but in no others. In both species they are immediately upstream of putative sensor kinase genes with nearly identical domain structures. In the marine Beggiatoaceae, a role for the TAACTGA repeats in

  12. Abundant Intergenic TAACTGA Direct Repeats and Putative Alternate RNA Polymerase β' Subunits in Marine Beggiatoaceae Genomes: Possible Regulatory Roles and Origins.

    Science.gov (United States)

    MacGregor, Barbara J

    2015-01-01

    The genome sequences of several giant marine sulfur-oxidizing bacteria present evidence of a possible post-transcriptional regulatory network that may have been transmitted to or from two distantly related bacteria lineages. The draft genome of a Cand. "Maribeggiatoa" filament from the Guaymas Basin (Gulf of California, Mexico) seafloor contains 169 sets of TAACTGA direct repeats and one indirect repeat, with two to six copies per set. Related heptamers are rarely or never found as direct repeats. TAACTGA direct repeats are also found in some other Beggiatoaceae, Thiocystis violascens, a range of Cyanobacteria, and five Bacteroidetes. This phylogenetic distribution suggests they may have been transmitted horizontally, but no mechanism is evident. There is no correlation between total TAACTGA occurrences and repeats per genome. In most species the repeat units are relatively short, but longer arrays of up to 43 copies are found in several Bacteroidetes and Cyanobacteria. The majority of TAACTGA repeats in the Cand. "Maribeggiatoa" Orange Guaymas (BOGUAY) genome are within several nucleotides upstream of a putative start codon, suggesting they may be binding sites for a post-transcriptional regulator. Candidates include members of the ribosomal protein S1, Csp (cold shock protein), and Csr (carbon storage regulator) families. No pattern was evident in the predicted functions of the open reading frames (ORFs) downstream of repeats, but some encode presumably essential products such as ribosomal proteins. Among these is an ORF encoding a possible alternate or modified RNA polymerase beta prime subunit, predicted to have the expected subunit interaction domains but lacking most catalytic residues. A similar ORF was found in the Thioploca ingrica draft genome, but in no others. In both species they are immediately upstream of putative sensor kinase genes with nearly identical domain structures. In the marine Beggiatoaceae, a role for the TAACTGA repeats in translational

  13. Cross-links between ribosomal proteins of 30S subunits in 70S tight couples and in 30S subunits.

    Science.gov (United States)

    Lambert, J M; Boileau, G; Cover, J A; Traut, R R

    1983-08-01

    Ribosome 70S tight couples and 30S subunits derived from them were modified with 2-iminothiolane under conditions where about two sulfhydryl groups per protein were added to the ribosomal particles. The 70S and 30S particles were not treated with elevated concentrations of NH4Cl, in contrast to those used in earlier studies. The modified particles were oxidized to promote disulfide bond formation. Proteins were extracted from the cross-linked particles by using conditions to preclude disulfide interchange. Disulfide-linked protein complexes were fractionated on the basis of charge by electrophoresis in polyacrylamide/urea gels at pH 5.5. The proteins from sequential slices of the urea gels were analyzed by two-dimensional diagonal polyacrylamide/sodium dodecyl sulfate gel electrophoresis. Final identification of proteins in cross-linked complexes was made by radioiodination of the proteins, followed by two-dimensional polyacrylamide/urea gel electrophoresis. Attention was focused on cross-links between 30S proteins. We report the identification of 27 cross-linked dimers and 2 trimers of 30S proteins, all but one of which were found in both 70S ribosomes and free 30S subunits in similar yield. Seven of the cross-links, S3-S13, S13-S21, S14-S19, S7-S12, S9-S13, S11-S21, and S6-S18-S21, have not been reported previously when 2-iminothiolane was used. Cross-links S3-S13, S13-S21, S7-S12, S11-S21, and S6-S18-S21 are reported for the first time. The identification of the seven new cross-links is illustrated and discussed in detail. Ten of the dimers reported in the earlier studies of Sommer & Traut (1976) [Sommer, A., & Traut, R. R. (1976) J. Mol. Biol. 106, 995-1015], using 30S subunits treated with high salt concentrations, were not found in the experiments reported here.

  14. Differential regulation of thyrotropin subunit apoprotein and carbohydrate biosynthesis by thyroid hormone

    International Nuclear Information System (INIS)

    The regulation of TSH apoprotein and carbohydrate biosynthesis by thyroid hormone was studied by incubating pituitaries from normal and hypothyroid (3 weeks post-thyroidectomy) rats in medium containing [14C]alanine and [3H] glucosamine. After 6 h, samples were sequentially treated with anti-TSH beta to precipitate TSH and free TSH beta, anti-LH beta to clear the sample of LH and free LH beta, then anti-LH alpha to precipitate free alpha-subunit. Total proteins were acid precipitated. All precipitates were subjected to electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, which were then sliced and assayed by scintillation spectrometry. In hypothyroid pituitaries plus medium, [14C]alanine incorporation in combined and free beta-subunits was 26 times normal and considerably greater than the 3.4-fold increase seen in total protein; combined and free alpha-subunits showed no specific increase in apoprotein synthesis. [3H]Glucosamine incorporation in combined alpha- and beta-subunits in hypothyroid samples was 13 and 21 times normal, respectively, and was greater than the 1.9-fold increase in total protein; free alpha-subunit showed no specific increase in carbohydrate synthesis. The glucosamine to alanine ratio, reflecting relative glycosylation of newly synthesized molecules, was increased in hypothyroidism for combined alpha-subunits, but not for combined beta-subunits, free alpha-subunits, or total proteins. In summary, short term hypothyroidism selectively stimulated TSH beta apoprotein synthesis and carbohydrate synthesis of combined alpha- and beta-subunits. Hypothyroidism also increased the relative glycosylation of combined alpha-subunit. Thus, thyroid hormone deficiency appears to alter the rate-limiting step in TSH assembly (i.e. beta-subunit synthesis) as well as the carbohydrate structure of TSH, which may play important roles in its biological function

  15. Copolymer semiconductors comprising thiazolothiazole or benzobisthiazole, or benzobisoxazole electron acceptor subunits, and electron donor subunits, and their uses in transistors and solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jenekhe, Samson A; Subramaniyan, Selvam; Ahmed, Eilaf; Xin, Hao; Kim, Felix Sunjoo

    2014-10-28

    The inventions disclosed, described, and/or claimed herein relate to copolymers comprising copolymers comprising electron accepting A subunits that comprise thiazolothiazole, benzobisthiazole, or benzobisoxazoles rings, and electron donating subunits that comprise certain heterocyclic groups. The copolymers are useful for manufacturing organic electronic devices, including transistors and solar cells. The invention also relates to certain synthetic precursors of the copolymers. Methods for making the copolymers and the derivative electronic devices are also described.

  16. Aluminosilicate nanoparticles for catalytic hydrocarbon cracking.

    Science.gov (United States)

    Liu, Yu; Pinnavaia, Thomas J

    2003-03-01

    Aluminosilicate nanoparticles containing 9.0-20 nm mesopores were prepared through the use of protozeolitic nanoclusters as the inorganic precursor and starch as a porogen. The calcined, porogen-free composition containing 2 mol % aluminum exhibited the porosity, hydrothermal stability, and acidity needed for the cracking of very large hydrocarbons. In fact, the hydrothermal stability of the nanoparticles to pure steam at 800 degrees C, along with the cumene cracking activity, surpassed the analogous performance properties of ultrastable Y zeolite, the main catalyst component of commercial cracking catalysts. The remarkable hydrothermal stability and catalytic reactivity of the new nanoparticles are attributable to a unique combination of two factors, the presence of protozeolitic nanoclusters in the pore walls and the unprecedented pore wall thickness (7-15 nm). In addition, the excellent catalytic longevity of the nanoparticles is most likely facilitated by the small domain size of the nanoparticles that greatly improves access to the acid sites on the pore walls and minimizes the diffusion length of coke precursors out of the pores. PMID:12603109

  17. Catalytic converter for next generation turbine engines

    Energy Technology Data Exchange (ETDEWEB)

    Saruhan, B.; Schulz, U.; Leyens, C. [German Aerospace Center (DLR), Inst. of Materials Research, Cologne (Germany)

    2004-07-01

    EB-PVD thermal barrier coatings (TBCs) are used on advanced turbine blades to increase the engine efficiency and improve the blade performance. partially yttria stabilized zirconia (PYSZ) is the standard material for current TBC applications. Lower thermal stability of the PYSZ-based TBCs, however, seriously affects the performance at demanding service temperatures. For the new generation turbines where higher operating gas temperatures (> 1200 C) are to expect, the performance of turbine blades can be improved by replacing the state-art-of-material PYSZ with superior thermal barrier coatings which belong to different crystal structures such as magnetoplumbite. Magnetoplumbite structure through its interlocking grain morphology and unique crystal structure provides essentially a sintering resistant, low thermal conductive layer, but also imparts a catalytic layer to reduce the environmentally harmful substances produced during propulsion and increase the catalytic performance. The complex structures of these compounds make it difficult to realize by conventional methods and requires careful adjustment of process parameters. The morphology and crystallographic aspects of these coatings as well as the mechanisms controlling the improvement are highlighted. (orig.)

  18. Catalytic reactor for low-Btu fuels

    Science.gov (United States)

    Smith, Lance; Etemad, Shahrokh; Karim, Hasan; Pfefferle, William C.

    2009-04-21

    An improved catalytic reactor includes a housing having a plate positioned therein defining a first zone and a second zone, and a plurality of conduits fabricated from a heat conducting material and adapted for conducting a fluid therethrough. The conduits are positioned within the housing such that the conduit exterior surfaces and the housing interior surface within the second zone define a first flow path while the conduit interior surfaces define a second flow path through the second zone and not in fluid communication with the first flow path. The conduit exits define a second flow path exit, the conduit exits and the first flow path exit being proximately located and interspersed. The conduits define at least one expanded section that contacts adjacent conduits thereby spacing the conduits within the second zone and forming first flow path exit flow orifices having an aggregate exit area greater than a defined percent of the housing exit plane area. Lastly, at least a portion of the first flow path defines a catalytically active surface.

  19. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm;

    2000-01-01

    The effect of electrochemical polarization on the catalytic SO2 oxidation in the molten V2O5-K2S2O7 system has been studied using a gold working electrode in the temperature range 400-460 degrees C. A similar experiment has been performed with the industrial catalyst VK-58. The aim of the present...... investigation was to study a possible non-Faradaic electrochemical promotion of the liquid-phase catalytic reaction. It has been shown that there are two negative potential promotion areas with maximum effects at approximately -0.1 and -0.2 V, and one positive potential promotion area with the maximum effect...... caused by the negative charge on the electrode. The Faradaic part of the promoting effect under positive polarization has been explained as the electrochemical pushing of the V(V) V(IV) equilibrium in the direction of V(V) formation. It has also been shown that when using the industrial VK-58 catalyst...

  20. Computational and Physical Analysis of Catalytic Compounds

    Science.gov (United States)

    Wu, Richard; Sohn, Jung Jae; Kyung, Richard

    2015-03-01

    Nanoparticles exhibit unique physical and chemical properties depending on their geometrical properties. For this reason, synthesis of nanoparticles with controlled shape and size is important to use their unique properties. Catalyst supports are usually made of high-surface-area porous oxides or carbon nanomaterials. These support materials stabilize metal catalysts against sintering at high reaction temperatures. Many studies have demonstrated large enhancements of catalytic behavior due to the role of the oxide-metal interface. In this paper, the catalyzing ability of supported nano metal oxides, such as silicon oxide and titanium oxide compounds as catalysts have been analyzed using computational chemistry method. Computational programs such as Gamess and Chemcraft has been used in an effort to compute the efficiencies of catalytic compounds, and bonding energy changes during the optimization convergence. The result illustrates how the metal oxides stabilize and the steps that it takes. The graph of the energy computation step(N) versus energy(kcal/mol) curve shows that the energy of the titania converges faster at the 7th iteration calculation, whereas the silica converges at the 9th iteration calculation.

  1. Ferredoxin-thioredoxin reductase: a catalytically active dithiol group links photoreduced ferredoxin to thioredoxin functional in photosynthetic enzyme regulation

    International Nuclear Information System (INIS)

    The mechanism by which the ferredoxin-thioredoxin system activates the target enzyme, NADP-malate dehydrogenase, was investigated by analyzing the sulfhydryl status of individual protein components with [14C]iodoacetate and monobromobimane. The data indicate that ferredoxin-thioredoxin reductase (FTR)--an iron-sulfur enzyme present in oxygenic photosynthetic organisms--is the first member of a thiol chain that links light to enzyme regulation. FTR possesses a catalytically active dithiol group localized on the 13 kDa (similar) subunit, that occurs in all species investigated and accepts reducing equivalents from photoreduced ferredoxin and transfers them stoichiometrically to the disulfide form of thioredoxin m. The reduced thioredoxin m, in turn, reduces NADP-malate dehydrogenase, thereby converting it from an inactive (S-S) to an active (SH) form. The means by which FTR is able to combine electrons (from photoreduced ferredoxin) with protons (from the medium) to reduce its active disulfide group remains to be determined

  2. Amino acid microsequencing of internal tryptic peptides of heme-regulated eukaryotic initiation factor 2 alpha subunit kinase: homology to protein kinases.

    Science.gov (United States)

    Chen, J J; Pal, J K; Petryshyn, R; Kuo, I; Yang, J M; Throop, M S; Gehrke, L; London, I M

    1991-01-01

    We have purified the heme-regulated eukaryotic initiation factor 2 alpha subunit (eIF-2 alpha) kinase (HRI) from rabbit reticulocytes for amino acid microsequencing. This kinase is a single 92-kDa polypeptide and migrates in perfect alignment with 32P-labeled HRI on SDS/PAGE. Its functions of binding ATP and of autophosphorylation and eIF-2 alpha phosphorylation are inhibited by hemin. The amino acid sequences of three tryptic peptides of HRI have been obtained. A search of the data base of the National Biomedical Research Foundation reveals that these amino acid sequences are unique and that two of these three sequences show homology to protein kinases. HRI peptide P-52 contains Asp-Phe-Gly, which is the most highly conserved short stretch of amino acids in catalytic domain VII of protein kinases. HRI peptide P-74 contains the conserved amino acid residues Asp-(Met)-Tyr-Ser-(Val)-Gly-Val found in catalytic domain IX of protein kinases [Hanks, S. K., Quinn, A. M. & Hunter, T. (1988) Science 241, 42-52]. These findings are consistent with the autokinase and eIF-2 alpha kinase activities of HRI. Synthetic HRI peptide P-74 is a very potent inhibitor of eIF-2 alpha phosphorylation by HRI. Since little is known about the function of conserved domain IX, P-74 peptide may be useful in elucidating the role of this domain of protein kinases. Images PMID:1671169

  3. Catalytic combustion in gas stoves - Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Hjelm, Anna-Karin [CATATOR AB, Lund (Sweden)

    2003-06-01

    Several independent studies show that gas stoves to some degree contribute to the indoor emissions of NO{sub x} especially in situations were the ventilation flow is poor. The peak-NO{sub x} concentrations can reach several hundred ppb but the integral concentration seldom exceeds about 20 - 50 ppb, which corresponds to an indoor-outdoor ratio of about 1 - 2.5. Epidemiological studies indicate increasing problems with respiratory symptoms in sensitive people at concentrations as low as 15 ppb of NO{sub 2}. Consequently, the NO{sub x}-concentration in homes where gas stoves are used is high enough to cause health effects. However, in situations where the ventilation flow is high (utilisation of ventilation hoods) the NO{sub x}-emissions are not likely to cause any health problems. This study has been aimed at investigating the possibilities to reduce the NO{sub x} emissions from gas stoves by replacing the conventional flame combustion with catalytic combustion. The investigation is requested by Swedish Gas Center, and is a following-up work of an earlier conducted feasibility study presented in April-2002. The present investigation reports on the possibility to use cheap and simple retro-fit catalytic design suggestions for traditional gas stoves. Experiments have been conducted with both natural and town gas, and parameters such as emissions of NO{sub x}, CO and unburned fuel gas and thermal efficiency, etc, have been examined and are discussed. The results show that it is possible to reduce the NO{sub x} emissions up to 80% by a simple retro-fit installation, without decreasing the thermal efficiency of the cooking plate. The measured source strengths correspond to indoor NO{sub x} concentrations that are below or equal to the average outdoor concentration, implying that no additional detrimental health effects are probable. The drawback of the suggested installations is that the concentration of CO and in some cases also CH{sub 4} are increased in the flue gases

  4. Amino acid sequence of the alpha subunit and computer modelling of the alpha and beta subunits of echicetin from the venom of Echis carinatus (saw-scaled viper).

    Science.gov (United States)

    Polgár, J; Magnenat, E M; Peitsch, M C; Wells, T N; Saqi, M S; Clemetson, K J

    1997-04-15

    Echicetin, a heterodimeric protein from the venom of Echis carinatus, binds to platelet glycoprotein Ib (GPIb) and so inhibits platelet aggregation or agglutination induced by various platelet agonists acting via GPIb. The amino acid sequence of the beta subunit of echicetin has been reported and found to belong to the recently identified snake venom subclass of the C-type lectin protein family. Echicetin alpha and beta subunits were purified. N-terminal sequence analysis provided direct evidence that the protein purified was echicetin. The paper presents the complete amino acid sequence of the alpha subunit and computer models of the alpha and beta subunits. The sequence of alpha echicetin is highly similar to the alpha and beta chains of various heterodimeric and homodimeric C-type lectins. Neither of the fully reduced and alkylated alpha or beta subunits of echicetin inhibited the platelet agglutination induced by von Willebrand factor-ristocetin or alpha-thrombin. Earlier reports about the inhibitory activity of reduced and alkylated echicetin beta subunit might have been due to partial reduction of the protein. PMID:9163349

  5. Polarographic catalytic wave of hydrogen--Parallel catalytic hydrogen wave of bovine serum albumin in thepresence of oxidants

    Institute of Scientific and Technical Information of China (English)

    GUO; Wei(过玮); LIU; Limin(刘利民); LIN; Hong(林洪); SONG; Junfeng(宋俊峰)

    2002-01-01

    A polarographic catalytic hydrogen wave of bovine serum albumin (BSA) at about -1.80 V (vs. SCE) in NH4Cl-NH3@H2O buffer is further catalyzed by such oxidants as iodate, persulfate and hydrogen peroxide, producing a kinetic wave. Studies show that the kinetic wave is a parallel catalytic wave of hydrogen, which resulted from that hydrogen ion is electrochemically reduced and chemically regenerated through oxidation of its reduction product, atomic hydrogen, by oxidants mentioned above. It is a new type of poralographic catalytic wave of protein, which is suggested to be named as a parallel catalytic hydrogen wave.

  6. Tuning of the Na,K-ATPase by the beta subunit

    DEFF Research Database (Denmark)

    Hilbers, Florian; Kopec, Wojciech; Isaksen, Toke Jost;

    2016-01-01

    The vital gradients of Na(+) and K(+) across the plasma membrane of animal cells are maintained by the Na,K-ATPase, an αβ enzyme complex, whose α subunit carries out the ion transport and ATP hydrolysis. The specific roles of the β subunit isoforms are less clear, though β2 is essential for motor...

  7. Regulation of KV channel voltage-dependent activation by transmembrane β subunits

    Directory of Open Access Journals (Sweden)

    Xiaohui eSun

    2012-04-01

    Full Text Available Voltage-activated K+ (KV channels are important for shaping action potentials and maintaining resting membrane potential in excitable cells. KV channels contain a central pore-gate domain (PGD surrounded by four voltage-sensing domains (VSD. The VSDs will change conformation in response to alterations of the membrane potential thereby inducing the opening of the PGD. Many KV channels are heteromeric protein complexes containing auxiliary β subunits. These β subunits modulate channel expression and activity to increase functional diversity and render tissue specific phenotypes. This review focuses on the KV β subunits that contain transmembrane (TM segments including the KCNE family and the β subunits of large conductance, Ca2+- and voltage-activated K+ (BK channels. These TM β subunits affect the voltage-dependent activation of KV α subunits. Experimental and computational studies have described the structural location of these β subunits in the channel complexes and the biophysical effects on VSD activation, PGD opening and VSD-PGD coupling. These results reveal some common characteristics and mechanistic insights into KV channel modulation by TM β subunits.

  8. Similar GABAA receptor subunit composition in somatic and axon initial segment synapses of hippocampal pyramidal cells.

    Science.gov (United States)

    Kerti-Szigeti, Katalin; Nusser, Zoltan

    2016-01-01

    Hippocampal pyramidal cells (PCs) express many GABAAR subunit types and receive GABAergic inputs from distinct interneurons. Previous experiments revealed input-specific differences in α1 and α2 subunit densities in perisomatic synapses, suggesting distinct IPSC decay kinetics. However, IPSC decays evoked by axo-axonic, parvalbumin- or cholecystokinin-expressing basket cells were found to be similar. Using replica immunogold labeling, here we show that all CA1 PC somatic and AIS synapses contain the α1, α2, β1, β2, β3 and γ2 subunits. In CA3 PCs, 90% of the perisomatic synapses are immunopositive for the α1 subunit and all synapses are positive for the remaining five subunits. Somatic synapses form unimodal distributions based on their immunoreactivity for these subunits. The α2 subunit densities in somatic synapses facing Cav2.1 (i.e. parvalbumin) or Cav2.2 (cholecystokinin) positive presynaptic active zones are comparable. We conclude that perisomatic synapses made by three distinct interneuron types have similar GABAA receptor subunit content. PMID:27537197

  9. A-Raf kinase is a new interacting partner of protein kinase CK2 beta subunit

    DEFF Research Database (Denmark)

    Boldyreff, B; Issinger, O G

    1997-01-01

    In a search for protein kinase CK2 beta subunit binding proteins using the two-hybrid system, more than 1000 positive clones were isolated. Beside clones for the alpha' and beta subunit of CK2, there were clones coding for a so far unknown protein, whose partial cDNA sequence was already deposite...

  10. Loss of Complex I activity in the Escherichia coli enzyme results from truncating the C-terminus of subunit K, but not from cross-linking it to subunits N or L.

    Science.gov (United States)

    Zhu, Shaotong; Canales, Alejandra; Bedair, Mai; Vik, Steven B

    2016-06-01

    Complex I is a multi-subunit enzyme of the respiratory chain with seven core subunits in its membrane arm (A, H, J, K, L, M, and N). In the enzyme from Escherichia coli the C-terminal ten amino acids of subunit K lie along the lateral helix of subunit L, and contribute to a junction of subunits K, L and N on the cytoplasmic surface. Using double cysteine mutagenesis, the cross-linking of subunit K (R99C) to either subunit L (K581C) or subunit N (T292C) was attempted. A partial yield of cross-linked product had no effect on the activity of the enzyme, or on proton translocation, suggesting that the C-terminus of subunit K has no dynamic role in function. To further elucidate the role of subunit K genetic deletions were constructed at the C-terminus. Upon the serial deletion of the last 4 residues of the C-terminus of subunit K, various results were obtained. Deletion of one amino acid had little effect on the activity of Complex I, but deletions of 2 or more amino acids led to total loss of enzyme activity and diminished levels of subunits L, M, and N in preparations of membrane vesicles. Together these results suggest that while the C-terminus of subunit K has no dynamic role in energy transduction by Complex I, it is vital for the correct assembly of the enzyme. PMID:26931547

  11. Structural characterization of recombinant crustacyanin subunits from the lobster Homarus americanus.

    Science.gov (United States)

    Ferrari, Michele; Folli, Claudia; Pincolini, Elisa; McClintock, Timothy S; Rössle, Manfred; Berni, Rodolfo; Cianci, Michele

    2012-08-01

    Crustacean crustacyanin proteins are linked to the production and modification of carapace colour, with direct implications for fitness and survival. Here, the structural and functional properties of the two recombinant crustacyanin subunits H(1) and H(2) from the American lobster Homarus americanus are reported. The two subunits are structurally highly similar to the corresponding natural apo crustacyanin CRTC and CRTA subunits from the European lobster H. gammarus. Reconstitution studies of the recombinant crustacyanin proteins H(1) and H(2) with astaxanthin reproduced the bathochromic shift of 85-95 nm typical of the natural crustacyanin subunits from H. gammarus in complex with astaxanthin. Moreover, correlations between the presence of crustacyanin genes in crustacean species and the resulting carapace colours with the spectral properties of the subunits in complex with astaxanthin confirmed this genotype-phenotype linkage. PMID:22869108

  12. Structural characterization of recombinant crustacyanin subunits from the lobster Homarus americanus.

    Science.gov (United States)

    Ferrari, Michele; Folli, Claudia; Pincolini, Elisa; McClintock, Timothy S; Rössle, Manfred; Berni, Rodolfo; Cianci, Michele

    2012-08-01

    Crustacean crustacyanin proteins are linked to the production and modification of carapace colour, with direct implications for fitness and survival. Here, the structural and functional properties of the two recombinant crustacyanin subunits H(1) and H(2) from the American lobster Homarus americanus are reported. The two subunits are structurally highly similar to the corresponding natural apo crustacyanin CRTC and CRTA subunits from the European lobster H. gammarus. Reconstitution studies of the recombinant crustacyanin proteins H(1) and H(2) with astaxanthin reproduced the bathochromic shift of 85-95 nm typical of the natural crustacyanin subunits from H. gammarus in complex with astaxanthin. Moreover, correlations between the presence of crustacyanin genes in crustacean species and the resulting carapace colours with the spectral properties of the subunits in complex with astaxanthin confirmed this genotype-phenotype linkage.

  13. HMW glutenin subunits in multiploid Aegilops species: composition analysis and molecular cloning of coding sequences

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Aegilops genus contains species closely related to wheat. Incommon with wheat, Aegilops species accumulate high molecular weight (HMW) glutenin subunits in their endospermic tissue. In this study, we investigated the composition of HMW glutenin subunits in four multiploid Aegilops species using SDS-PAGE analysis. Furthermore, by working with Ae. ventricosa, we established an efficient genomic PCR condition for simultaneous amplification of DNA sequences coding for either x-ory-type HMW glutenin subunits from polyploid Aegilops species. Using the genomic PCR condition, we amplified and subsequently cloned two DNA fragments that may code for HMW glutenin subunits in Ae. ventricosa. Based on an analysis of the deduced amino acid sequences, we concluded that the two cloned sequences encode one x- and one y-type of HMW glutenin subunit, respectively.

  14. In situ and operando transmission electron microscopy of catalytic materials

    DEFF Research Database (Denmark)

    Crozier, Peter A.; Hansen, Thomas Willum

    2015-01-01

    measurements of gas-phase catalytic products. To overcome this deficiency, operando TEM techniques are being developed that combine atomic characterization with the simultaneous measurement of catalytic products. This article provides a short review of the current status and major developments in the...

  15. Catalytic activities of platinum nanotubes: a density functional study

    Science.gov (United States)

    Mukherjee, Prajna; Gupta, Bikash C.; Jena, Puru

    2015-10-01

    In this work we investigate the catalytic properties of platinum nanotubes using density functional theory based calculations. In particular, we study the dissociation of hydrogen and oxygen molecules as well as oxidation of CO molecules. The results indicate that platinum nanotubes have good catalytic properties and can be effectively used in converting CO molecule to CO2.

  16. Including lateral interactions into microkinetic models of catalytic reactions

    DEFF Research Database (Denmark)

    Hellman, Anders; Honkala, Johanna Karoliina

    2007-01-01

    In many catalytic reactions lateral interactions between adsorbates are believed to have a strong influence on the reaction rates. We apply a microkinetic model to explore the effect of lateral interactions and how to efficiently take them into account in a simple catalytic reaction. Three...

  17. Catalytic pyrolysis of oilsand bitumen over nanoporous catalysts.

    Science.gov (United States)

    Lee, See-Hoon; Heo, Hyeon Su; Jeong, Kwang-Eun; Yim, Jin-Heong; Jeon, Jong-Ki; Jung, Kyeong Youl; Ko, Young Soo; Kim, Seung-Soo; Park, Young-Kwon

    2011-01-01

    The catalytic cracking of oilsand bitumen was performed over nanoporous materials at atmospheric conditions. The yield of gas increased with application of nanoporous catalysts, with the catalytic conversion to gas highest for Meso-MFI. The cracking activity seemed to correlate with pore size rather than weak acidity or surface area. PMID:21446540

  18. Functionalized TUD-1: synthesis, characterization and (photo-)catalytic performance

    NARCIS (Netherlands)

    Hamdy M. Saad, M.S.

    2005-01-01

    The new mesoporous material; TUD-1 is chosen of which the synthesis, characterization, and functionalization for (photo)-catalytic performance are extensively investigated in this study. The synthesis of the new catalytic materials M TUD-1 (M = Ti, V, Cr, Mo, Fe, Co and Cu) is carried out through an

  19. The action of calcium channel blockers on recombinant L-type calcium channel α1-subunits

    Science.gov (United States)

    Morel, Nicole; Buryi, Vitali; Feron, Olivier; Gomez, Jean-Pierre; Christen, Marie-Odile; Godfraind, Théophile

    1998-01-01

    CHO cells expressing the α1C-a subunit (cardiac isoform) and the α1C-b subunit (vascular isoform) of the voltage-dependent L-type Ca2+ channel were used to investigate whether tissue selectivity of Ca2+ channel blockers could be related to different affinities for α1C isoforms.Inward current evoked by the transfected α1 subunit was recorded by the patch-clamp technique in the whole-cell configuration.Neutral dihydropyridines (nifedipine, nisoldipine, (+)-PN200-110) were more potent inhibitors of α1C-b-subunit than of α1C-a-subunit. This difference was more marked at a holding potential of −100 mV than at −50 mV. SDZ 207-180 (an ionized dihydropyridine) exhibited the same potency on the two isoforms.Pinaverium (ionized non-dihydropyridine derivative) was 2 and 4 fold more potent on α1C-a than on α1C-b subunit at Vh of −100 mV and −50 mV, respectively. Effects of verapamil were identical on the two isoforms at both voltages.[3H]-(+)-PN 200-110 binding experiments showed that neutral dihydropyridines had a higher affinity for the α1C-b than for the α1C-a subunit. SDZ 207-180 had the same affinity for the two isoforms and pinaverium had a higher affinity for the α1C-a subunit than for the α1C-b subunit.These results indicate marked differences among Ca2+ channel blockers in their selectivity for the α1C-a and α1C-b subunits of the Ca2+ channel. PMID:9846638

  20. The action of calcium channel blockers on recombinant L-type calcium channel alpha1-subunits.

    Science.gov (United States)

    Morel, N; Buryi, V; Feron, O; Gomez, J P; Christen, M O; Godfraind, T

    1998-11-01

    1. CHO cells expressing the alpha(1C-a) subunit (cardiac isoform) and the alpha(1C-b) subunit (vascular isoform) of the voltage-dependent L-type Ca2+ channel were used to investigate whether tissue selectivity of Ca2+ channel blockers could be related to different affinities for alpha1C isoforms. 2. Inward current evoked by the transfected alpha1 subunit was recorded by the patch-clamp technique in the whole-cell configuration. 3. Neutral dihydropyridines (nifedipine, nisoldipine, (+)-PN200-110) were more potent inhibitors of alpha(1C-)b-subunit than of alpha(1C-a)-subunit. This difference was more marked at a holding potential of -100 mV than at -50 mV. SDZ 207-180 (an ionized dihydropyridine) exhibited the same potency on the two isoforms. 4. Pinaverium (ionized non-dihydropyridine derivative) was 2 and 4 fold more potent on alpha(1C-a) than on alpha(1C-b) subunit at Vh of -100 mV and -50 mV, respectively. Effects of verapamil were identical on the two isoforms at both voltages. 5. [3H]-(+)-PN 200-110 binding experiments showed that neutral dihydropyridines had a higher affinity for the alpha(1C-b) than for the alpha(1C-a) subunit. SDZ 207-180 had the same affinity for the two isoforms and pinaverium had a higher affinity for the alpha(1C-a) subunit than for the alpha(1C-b) subunit. 6. These results indicate marked differences among Ca2+ channel blockers in their selectivity for the alpha(1C-a) and alpha(1C-b) subunits of the Ca2+ channel. PMID:9846638

  1. Catalytic Decomposition of Methylene Chloride by Sulfated Titania Catalysts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Catalytic decomposition of methylene chloride in air below 300℃ was studied.Sulfated titania was very effective in converting 959ppm methylene chloride selectively to CO,CO2 and HCl.Complete decomposition of methylene chloride was achieved at low temperature(275℃).It was found that the acidic property of catalyst was a determinant factor for the catalytic activity.The presence of water vapor in the feed stream remarkably reduced the catalytic activity,which could be due to the blockage of acidic sites on the surface of catalyst by water molecules.A bifunctional catalyst comprising copper oxide was developed to improve the selectivity of catalytic oxidation,which indicated that copper oxide can promote the deep oxidation of methylene chloride.The crystal form of TiO2 imposes an important influence upon the catalytic oxidation.

  2. Relationship between structure and catalytic performance of dealuminated Y zeolites

    International Nuclear Information System (INIS)

    Dealuminated Y zeolites which have been prepared by hydrothermal and chemical treatments show differences in catalytic performance when tested fresh; however, these differences disappear after the zeolites have been steamed. The catalytic behavior of fresh and steamed zeolites is directly related to zeolite structural and chemical characteristics. Such characteristics determine the strength and density of acid sites for catalytic cracking. Dealuminated zeolites were characterized using x-ray diffraction, porosimetry, solid-state NMR and elemental analysis. Hexadecane cracking was used as a probe reaction to determine catalytic properties. Cracking activity was found to be proportional to total aluminum content in the zeolite. Product selectivity was dependent on unit cell size, presence of extra framework alumina and spatial distribution of active sites. The results from this study elucidate the role that zeolite structure plays in determining catalytic performance

  3. Contact structure for use in catalytic distillation

    Science.gov (United States)

    Jones, Jr., Edward M.

    1984-01-01

    A method for conducting catalytic chemical reactions and fractionation of the reaction mixture comprising feeding reactants into a distillation column reactor contracting said reactant in liquid phase with a fixed bed catalyst in the form of a contact catalyst structure consisting of closed porous containers containing the catatlyst for the reaction and a clip means to hold and support said containers, which are disposed above, i.e., on the distillation trays in the tower. The trays have weir means to provide a liquid level on the trays to substantially cover the containers. In other words, the trays function in their ordinary manner with the addition thereto of the catalyst. The reaction mixture is concurrently fractionated in the column.

  4. Stoichiometric and Catalytic Synthesis of Alkynylphosphines

    Directory of Open Access Journals (Sweden)

    Annie-Claude Gaumont

    2012-12-01

    Full Text Available Alkynylphosphines or their borane complexes are available either through C–P bond forming reactions or through modification of the phosphorus or the alkynyl function of various alkynyl phosphorus derivatives. The latter strategy, and in particular the one involving phosphoryl reduction by alanes or silanes, is the method of choice for preparing primary and secondary alkynylphosphines, while the former strategy is usually employed for the synthesis of tertiary alkynylphosphines or their borane complexes. The classical C–P bond forming methods rely on the reaction between halophosphines or their borane complexes with terminal acetylenes in the presence of a stoichiometric amount of organometallic bases, which precludes the access to alkynylphosphines bearing sensitive functional groups. In less than a decade, efficient catalytic procedures, mostly involving copper complexes and either an electrophilic or a nucleophilic phosphorus reagent, have emerged. By proceeding under mild conditions, these new methods have allowed a significant broadening of the substituent scope and structure complexity.

  5. Studies on Catalytic Conversion of Ethylene

    Institute of Scientific and Technical Information of China (English)

    Fuyu Liu; Chunyi Li; Xue Ding; Xinghua You

    2007-01-01

    FCC dry gas contains a large amount of ethylene.It is used by most of the refineries in China as fuel or simply burned in atmosphere.Few refineries make good use of the dry gas,so the precious ethylene resource in the dry gas is wasted.In this article,the possibility of catalytic conversion of ethylene to C3,C4,and some high molecular weight hydrocarbons in a fixed bed micro-reactor using LTB-1 catalyst,with pure ethylene as feedstock was studied.Effects of reaction temperature,reaction pressure,and feedstock flow rate,on the conversion of ethylene and the distribution of products were investigated to determine the proper reaction parameters to be used in practice.Good results indicate that this study may provide a new way of using the ethylene resource in the FCC dry gas.

  6. Ubiquitous ``glassy'' relaxation in catalytic reaction networks

    Science.gov (United States)

    Awazu, Akinori; Kaneko, Kunihiko

    2009-10-01

    Study of reversible catalytic reaction networks is important not only as an issue for chemical thermodynamics but also for protocells. From extensive numerical simulations and theoretical analysis, slow relaxation dynamics to sustain nonequlibrium states are commonly observed. These dynamics show two types of salient behaviors that are reminiscent of glassy behavior: slow relaxation along with the logarithmic time dependence of the correlation function and the emergence of plateaus in the relaxation-time course. The former behavior is explained by the eigenvalue distribution of a Jacobian matrix around the equilibrium state that depends on the distribution of kinetic coefficients of reactions. The latter behavior is associated with kinetic constraints rather than metastable states and is due to the absence of catalysts for chemicals in excess and the negative correlation between two chemical species. Examples are given and generality is discussed with relevance to bottleneck-type dynamics in biochemical reactions as well.

  7. Scanning electrochemical microscopy of individual catalytic nanoparticles.

    Science.gov (United States)

    Sun, Tong; Yu, Yun; Zacher, Brian J; Mirkin, Michael V

    2014-12-15

    Electrochemistry at individual metal nanoparticles (NPs) can provide new insights into their electrocatalytic behavior. Herein, the electrochemical activity of single AuNPs attached to the catalytically inert carbon surface is mapped by using extremely small (≥3 nm radius) polished nanoelectrodes as tips in the scanning electrochemical microscope (SECM). The use of such small probes resulted in the spatial resolution significantly higher than in previously reported electrochemical images. The currents produced by either rapid electron transfer or the electrocatalytic hydrogen evolution reaction at a single 10 or 20 nm NP were measured and quantitatively analyzed. The developed methodology should be useful for studying the effects of nanoparticle size, geometry, and surface attachment on electrocatalytic activity in real-world application environment. PMID:25332196

  8. Catalytic Synthesis of Nitriles in Continuous Flow

    DEFF Research Database (Denmark)

    Nordvang, Emily Catherine

    The objective of this thesis is to report the development of a new, alternative process for the flexible production of nitrile compounds in continuous flow. Nitriles are an important class of compounds that find applications as solvents, chemical intermediates and pharmaceutical compounds......, alternative path to acetonitrile from ethanol via the oxidative dehydrogenation of ethylamine. The catalytic activity and product ratios of the batch and continuous flow reactions are compared and the effect of reaction conditions on the reaction is investigated. The effects of ammonia in the reaction...... dehydrogenation of ethylamine and post-reaction purging.Chapter 4 outlines the application of RuO2/Al2O3 catalysts to the oxidative dehydrogenation of benzylamine in air, utilizing a new reaction setup. Again, batch and continuous flow reactions are compared and the effects of reaction conditions, ammonia...

  9. Flame assisted synthesis of catalytic ceramic membranes

    DEFF Research Database (Denmark)

    Johansen, Johnny; Mosleh, Majid; Johannessen, Tue;

    2004-01-01

    will be spherical due to the fast coalescence at the high temperatures in the flame. The primary product from the flame pyrolysis is an aerosol of metal oxide nanoparticles. The aerosol gas from the flame can be utilized for several different purposes, depending on the precursors fed to the flame. With the present...... technology it is possible to make supported catalysts, composite metal oxides, catalytically active surfaces, and porous ceramic membranes. Membrane layers can be formed by using a porous substrate tube (or surface) as a nano-particle filter. The aerosol gas from the flame is led through a porous substrate...... tube, where a part of the gas is sucked through the wall of the substrate, thereby creating a thin filter cake on the inner surface of the substrate tube. The top-layer can be deposited directly on a coarse pore structure. Since the Brownian motion of the aerosol particles is fast compared to the fluid...

  10. Carbon nanofibers: a versatile catalytic support

    Directory of Open Access Journals (Sweden)

    Nelize Maria de Almeida Coelho

    2008-09-01

    Full Text Available The aim of this article is present an overview of the promising results obtained while using carbon nanofibers based composites as catalyst support for different practical applications: hydrazine decomposition, styrene synthesis, direct oxidation of H2S into elementary sulfur and as fuel-cell electrodes. We have also discussed some prospects of the use of these new materials in total combustion of methane and in ammonia decomposition. The macroscopic carbon nanofibers based composites were prepared by the CVD method (Carbon Vapor Deposition employing a gaseous mixture of hydrogen and ethane. The results showed a high catalytic activity and selectivity in comparison to the traditional catalysts employed in these reactions. The fact was attributed, mainly, to the morphology and the high external surface of the catalyst support.

  11. Propulsion Mechanism of Catalytic Microjet Engines

    Science.gov (United States)

    Fomin, Vladimir M.; Hippler, Markus; Magdanz, Veronika; Soler, Lluís; Sanchez, Samuel; Schmidt, Oliver G.

    2014-01-01

    We describe the propulsion mechanism of the catalytic microjet engines that are fabricated using rolled-up nanotech. Microjets have recently shown numerous potential applications in nanorobotics but currently there is a lack of an accurate theoretical model that describes the origin of the motion as well as the mechanism of self-propulsion. The geometric asymmetry of a tubular microjet leads to the development of a capillary force, which tends to propel a bubble toward the larger opening of the tube. Because of this motion in an asymmetric tube, there emerges a momentum transfer to the fluid. In order to compensate this momentum transfer, a jet force acting on the tube occurs. This force, which is counterbalanced by the linear drag force, enables tube velocities of the order of 100 μm/s. This mechanism provides a fundamental explanation for the development of driving forces that are acting on bubbles in tubular microjets. PMID:25177214

  12. Catalytic Hydrolysis of Borohydride for Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    WANG Lianbang; ZHAN Xingyue; YANG Zhenzhen; MA Chun'an

    2011-01-01

    Borohydrides present interesting options for the electrochemical power generation acting either as hydrogen source or anodic fuel for direct borohydride fuel cells(DBFC).In this work,Mg-Ni composite synthesized by mechanically alloying method,used as the catalyst for the hydrolysis of borohydride,has been investigated.Co-doping treatment has been carried out for the purpose of improving the hydrolysis rate further.The as-prepared and Co-doped Mg-Ni composites with low cost showed high catalytic activity to the hydrolysis of borohydride for hydrogen generation.After Co-doping,the hydrogen generation rate was around 280 ml·g-1·min-1.Borohydride would be a promising hydrogen source for fuel cells.

  13. Catalytic Acylation of Ethylidenecyclohexane over Zeolite Catalysts

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Some environmentally friendly catalysts such as HY and H-β zeolites,various cation-exchanged β zeolites,and some other solids have been used in the acylation reaction of ethylidenecyclohexane with acetic anhydride at room temperature to synthesize 3-(1-cyclohexenyl)-2-butanone instead of conventional catalysts.The effect of the amount of HY zeolite used on the acylation reaction was investigated.The yield of the acylated product was 72% in the case of n(ethylidenecyclohexane)∶n(acetic anhydride)∶m(HY zeolite)=1 mmol∶10 mmol∶0.100 g,reaction temperature:25 ℃,and reaction time:2 h.The regenerated HY zeolite showed almost the same catalytic activity as the fresh zeolite.

  14. Catalytic hot gas cleaning of gasification gas

    Energy Technology Data Exchange (ETDEWEB)

    Simell, P. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1997-12-31

    The aim of this work was to study the catalytic cleaning of gasification gas from tars and ammonia. In addition, factors influencing catalytic activity in industrial applications were studied, as well as the effects of different operation conditions and limits. Also the catalytic reactions of tar and ammonia with gasification gas components were studied. The activities of different catalyst materials were measured with laboratory-scale reactors fed by slip streams taken from updraft and fluid bed gasifiers. Carbonate rocks and nickel catalysts proved to be active tar decomposing catalysts. Ammonia decomposition was in turn facilitated by nickel catalysts and iron materials like iron sinter and iron dolomite. Temperatures over 850 deg C were required at 2000{sup -1} space velocity at ambient pressure to achieve almost complete conversions. During catalytic reactions H{sub 2} and CO were formed and H{sub 2}O was consumed in addition to decomposing hydrocarbons and ammonia. Equilibrium gas composition was almost achieved with nickel catalysts at 900 deg C. No deactivation by H{sub 2}S or carbon took place in these conditions. Catalyst blocking by particulates was avoided by using a monolith type of catalyst. The apparent first order kinetic parameters were determined for the most active materials. The activities of dolomite, nickel catalyst and reference materials were measured in different gas atmospheres using laboratory apparatus. This consisted of nitrogen carrier, toluene as tar model compound, ammonia and one of the components H{sub 2}, H{sub 2}O, CO, CO{sub 2}, CO{sub 2}+H{sub 2}O or CO+CO{sub 2}. Also synthetic gasification gas was used. With the dolomite and nickel catalyst the highest toluene decomposition rates were measured with CO{sub 2} and H{sub 2}O. In gasification gas, however, the rate was retarded due to inhibition by reaction products (CO, H{sub 2}, CO{sub 2}). Tar decomposition over dolomite was modelled by benzene reactions with CO{sub 2}, H

  15. Catalytic combustion in small wood burning appliances

    Energy Technology Data Exchange (ETDEWEB)

    Oravainen, H. [VTT Energy, Jyvaeskylae (Finland)

    1996-12-31

    There is over a million hand fired small heating appliances in Finland where about 5,4 million cubic meters of wood fuel is used. Combustion in such heating appliances is a batch-type process. In early stages of combustion when volatiles are burned, the formation of carbon monoxide (CO) and other combustible gases are difficult to avoid when using fuels that have high volatile matter content. Harmful emissions are formed mostly after each fuel adding but also during char burnout period. When the CO-content in flue gases is, say over 0.5 %, also other harmful emissions will be formed. Methane (CH{sub 4}) and other hydrocarbons are released and the amount of polycyclic aromatic hydrocarbons (PAH)-compounds can be remarkable. Some PAH-compounds are very carcinogenic. It has been estimated that in Finland even more than 90 % of hydrocarbon and PAH emissions are due to small scale wood combustion. Emissions from transportation is excluded from these figures. That is why wood combustion has a net effect on greenhouse gas phenomena. For example carbon monoxide emissions from small scale wood combustion are two fold compared to that of energy production in power plants. Methane emission is of the same order as emission from transportation and seven fold compared with those of energy production. Emissions from small heating appliances can be reduced by developing the combustion techniques, but also by using other means, for example catalytic converters. In certain stages of the batch combustion, temperature is not high enough, gas mixing is not good enough and residence time is too short for complete combustion. When placed to a suitable place inside a heating appliance, a catalytic converter can oxidize unburned gases in the flue gas into compounds that are not harmful to the environment. (3 refs.)

  16. Plasma Catalytic Synthesis of Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-Tao; GUO Ying; MA Teng-Cai

    2011-01-01

    We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles, using AgNO3 as the precursor, ethanol as the solvent and reducing agent, and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant. The plasma is generated by an atmospheric argon dielectric barrier discharge jet. Silver nanoparticles are produced instantly once the plasma is ignited. The system is not heated so it is necessary to use traditional chemical methods. The samples are characterized by UV-visible absorbance and transmission electron microscopy. For glow discharge mode no obvious silver nanoparticles are observed. For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.%We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles,using AgNO3 as the precursor,ethanol as the solvent and reducing agent,and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant.The plasma is generated by an atmospheric argon dielectric barrier discharge jet.Silver nanoparticles are produced instantly once the plasma is ignited.The system is not heated so it is necessary to use traditional chemical methods.The samples are characterized by UV-visible absorbance and transmission electron microscopy.For glow discharge mode no obvious silver nanoparticles are observed.For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.The study of silver nanoparticles has been an extremely active area in recent years because of their important physical and chemical properties as a catalyst and antimicrobial reagent,for example.A number of methods for silver nanoparticle preparation have been developed,[1-3] among them chemical reduction is

  17. Action des pots catalytiques sur les polluants non réglementés How Catalytic Mufflers Act on Unregulated Pollutants

    Directory of Open Access Journals (Sweden)

    Degobert P.

    2006-11-01

    Full Text Available L'installation de pots catalytiques sur les véhicules, envisagée essentiellement pour réduire le niveau des polluants actuellement réglementés (oxyde de carbone, hydrocarbures imbrûlés, oxydes d'azote, aura-t-elle des effets bénéfiques ou néfastes sur les polluants non réglementés ? Pour éclaircir cette question, cette étude compare sur des véhicules les plus comparables possibles du point de vue conception et équipements, les émissions des voitures non dépolluées et celles de voitures dépolluées , c'est-à-dire équipées de pots catalytiques d'oxydation, de pots catalytiques multifonctionnels ou de systèmes de combustion en mélange pauvre. Les polluants non réglementés pris en considération sont les aldéhydes, les sulfates, l'anhydride sulfureux, l'hydrogène sulfuré, l'oxysulfure de carbone, le cyanogène, l'acide cyanhydrique, l'acide nitrique, les aromatiques légers, les hydrocarbures aromatiques polycycliques, ces derniers en liaison avec leurs propriétés mutagènes. Le catalyseur a été considéré dans différents états : neuf, vieilli, empoisonné : l'influence des déréglages des systèmes de contrôle (avance, sonde à oxygène, allumage, etc. a été prise en compte. Il apparaît que la présence de catalyseur fonctionnant dans des conditions normales se révèle en général bénéfique sur la majorité des polluants ou tout au moins indifférente sur certains polluants. En outre les déréglages éventuels n'entraîneraient pas de concentrations alarmantes de ces polluants non réglementés. Will the equipping of vehicles with catalytic mufflers, planned mainly to reduce the level of currently regulated pollutants (carbon monoxide, unburned hydrocarbons , nitrogen oxides, have a beneficial or harmful effect on unregulated pollutants? To elucidate this question this article considers the vehicles that are the most comparable possible from the standpoint of design and equipment to compare emissions

  18. An experimental study of diffusion and convection of multicomponent gases through catalytic and non-catalytic membranes

    NARCIS (Netherlands)

    Veldsink, J.W.; Versteeg, G.F.; Swaaij, W.P.M. van

    1994-01-01

    Diffusion of binary and ternary gases through catalytic and non-catalytic membranes has been studied experimentally at atmospheric pressure. These experiments were conducted in a modified Wicke-Kallenbach diffusion cell consisting of two continuously stirred gas volumes separated by a membrane. The

  19. Dominant Rio1 kinase/ATPase catalytic mutant induces trapping of late pre-40S biogenesis factors in 80S-like ribosomes.

    Science.gov (United States)

    Ferreira-Cerca, Sébastien; Kiburu, Irene; Thomson, Emma; LaRonde, Nicole; Hurt, Ed

    2014-07-01

    During eukaryotic ribosome biogenesis, members of the conserved atypical serine/threonine protein kinase family, the RIO kinases (Rio1, Rio2 and Rio3) function in small ribosomal subunit biogenesis. Structural analysis of Rio2 indicated a role as a conformation-sensing ATPase rather than a kinase to regulate its dynamic association with the pre-40S subunit. However, it remained elusive at which step and by which mechanism the other RIO kinase members act. Here, we have determined the crystal structure of the human Rio1-ATP-Mg(2+) complex carrying a phosphoaspartate in the active site indicative of ATPase activity. Structure-based mutations in yeast showed that Rio1's catalytic activity regulates its pre-40S association. Furthermore, we provide evidence that Rio1 associates with a very late pre-40S via its conserved C-terminal domain. Moreover, a rio1 dominant-negative mutant defective in ATP hydrolysis induced trapping of late biogenesis factors in pre-ribosomal particles, which turned out not to be pre-40S but 80S-like ribosomes. Thus, the RIO kinase fold generates a versatile ATPase enzyme, which in the case of Rio1 is activated following the Rio2 step to regulate one of the final 40S maturation events, at which time the 60S subunit is recruited for final quality control check.

  20. Preparation of Pt-Ru hydrophobic catalysts and catalytic activities for liquid phase catalytic exchange reaction

    International Nuclear Information System (INIS)

    Pt/C and Pt-Ru/C catalysts with different ratios of Pt to Ru were synthesized, using ethylene glycol as both the dispersant and reducing agent at 1-2 MPa by microwave-assisted method. The catalysts were characterized by XRD, TEM and XPS. The mean particle sizes of the Pt/C and Pt-Ru/C catalysts were 1.9-2.0 nm. Pt and Ru existed as Pt(0), Pt(II), Pt(IV), Ru(0) and Ru(IV) for Pt-Ru/C catalysts, respectively. The face-centered cubic structure of the active mental particles would be changed upon the addition of Ru gradually. Then polytetrafluoroethylene and carbon-supported Pt and Pt-Ru catalysts were supported on foamed nickel to obtain hydrophobic catalysts. The catalytic activity was increased for liquid phase catalytic exchange (LPCE) when uniform Pt based hydrophobic catalysts was mixed into appropriate Ru. Hydrogen isotope exchange reaction occurs between hydration layer(H2O)nH+(ads)(n≥2) and D atoms due to intact water molecules being on Pt surface for LPCE. Water molecules have a tendency to dissociate to OH(ads) and H(ads) on metal Ru surface, and there is the other reaction path for Pt-Ru binary catalysts, which is probably the main reason of the increase of the catalytic activity of the hydrophobic Pt-Ru catalyst. (authors)