WorldWideScience

Sample records for catalytic subunit pris

  1. PRIS analyses world trends

    International Nuclear Information System (INIS)

    Spiegelberg, R.

    1990-01-01

    The International Atomic Energy Agency (IAEA) maintains a computerized data bank which contains general information on nuclear power reactors in member states and Taiwan, China. The power reactor information system (PRIS), contains information on power reactors in operation, under construction, planned and shut down, as well as performance data and operating experience. The IAEA has been collecting such data since 1970. Member states and international organizations can access PRIS on-line, and next year the IAEA plans to offer member states Micro-PRIS, a personal computer version of PRIS. (author)

  2. Role of regulatory subunits and protein kinase inhibitor (PKI) in determining nuclear localization and activity of the catalytic subunit of protein kinase A.

    Science.gov (United States)

    Wiley, J C; Wailes, L A; Idzerda, R L; McKnight, G S

    1999-03-05

    Regulation of protein kinase A by subcellular localization may be critical to target catalytic subunits to specific substrates. We employed epitope-tagged catalytic subunit to correlate subcellular localization and gene-inducing activity in the presence of regulatory subunit or protein kinase inhibitor (PKI). Transiently expressed catalytic subunit distributed throughout the cell and induced gene expression. Co-expression of regulatory subunit or PKI blocked gene induction and prevented nuclear accumulation. A mutant PKI lacking the nuclear export signal blocked gene induction but not nuclear accumulation, demonstrating that nuclear export is not essential to inhibit gene induction. When the catalytic subunit was targeted to the nucleus with a nuclear localization signal, it was not sequestered in the cytoplasm by regulatory subunit, although its activity was completely inhibited. PKI redistributed the nuclear catalytic subunit to the cytoplasm and blocked gene induction, demonstrating that the nuclear export signal of PKI can override a strong nuclear localization signal. With increasing PKI, the export process appeared to saturate, resulting in the return of catalytic subunit to the nucleus. These results demonstrate that both the regulatory subunit and PKI are able to completely inhibit the gene-inducing activity of the catalytic subunit even when the catalytic subunit is forced to concentrate in the nuclear compartment.

  3. Characterisation by nuclear magnetic resonance of the β catalytic subunit of the chloroplastic coupling factor

    International Nuclear Information System (INIS)

    Andre, Francois

    1986-09-01

    This academic work addressed the use of nuclear magnetic resonance (NMR) for the structural and dynamic study of the catalytic sub-unit of the extrinsic section of a membrane complex, the chloroplastic H+-ATPase. This work included the development of a protocol of preparation and quantitative purification of β subunits isolated from the CF1 for the elaboration of a concentrated sample for NMR, and then the study of the β subunit by using proton NMR

  4. Catalytic Subunit 1 of Protein Phosphatase 2A Is a Subunit of the STRIPAK Complex and Governs Fungal Sexual Development.

    Science.gov (United States)

    Beier, Anna; Teichert, Ines; Krisp, Christoph; Wolters, Dirk A; Kück, Ulrich

    2016-06-21

    The generation of complex three-dimensional structures is a key developmental step for most eukaryotic organisms. The details of the molecular machinery controlling this step remain to be determined. An excellent model system to study this general process is the generation of three-dimensional fruiting bodies in filamentous fungi like Sordaria macrospora Fruiting body development is controlled by subunits of the highly conserved striatin-interacting phosphatase and kinase (STRIPAK) complex, which has been described in organisms ranging from yeasts to humans. The highly conserved heterotrimeric protein phosphatase PP2A is a subunit of STRIPAK. Here, catalytic subunit 1 of PP2A was functionally characterized. The Δpp2Ac1 strain is sterile, unable to undergo hyphal fusion, and devoid of ascogonial septation. Further, PP2Ac1, together with STRIPAK subunit PRO22, governs vegetative and stress-related growth. We revealed in vitro catalytic activity of wild-type PP2Ac1, and our in vivo analysis showed that inactive PP2Ac1 blocks the complementation of the sterile deletion strain. Tandem affinity purification, followed by mass spectrometry and yeast two-hybrid analysis, verified that PP2Ac1 is a subunit of STRIPAK. Further, these data indicate links between the STRIPAK complex and other developmental signaling pathways, implying the presence of a large interconnected signaling network that controls eukaryotic developmental processes. The insights gained in our study can be transferred to higher eukaryotes and will be important for understanding eukaryotic cellular development in general. The striatin-interacting phosphatase and kinase (STRIPAK) complex is highly conserved from yeasts to humans and is an important regulator of numerous eukaryotic developmental processes, such as cellular signaling and cell development. Although functional insights into the STRIPAK complex are accumulating, the detailed molecular mechanisms of single subunits are only partially understood

  5. MicroPRIS user's guide

    International Nuclear Information System (INIS)

    1991-01-01

    MicroPRIS is a new service of the IAEA Power Reactor Information System (PRIS) for the Member States of IAEA. MicroPRIS makes the IAEA database on nuclear power plants and their operating experience available to Member States on computer diskettes in a form readily accessible by standard commercially available personal computer packages. The aim of this publication is to provide the users of the PC version of PRIS data with description of the subset of the full PRIS database contained in MicroPRIS (release 1990), description of files and file structures, field descriptions and definitions, extraction and selection guide and with the method of calculation of a number of important performance indicators used by the IAEA

  6. Catalytic Subunit 1 of Protein Phosphatase 2A Is a Subunit of the STRIPAK Complex and Governs Fungal Sexual Development

    Directory of Open Access Journals (Sweden)

    Anna Beier

    2016-06-01

    Full Text Available The generation of complex three-dimensional structures is a key developmental step for most eukaryotic organisms. The details of the molecular machinery controlling this step remain to be determined. An excellent model system to study this general process is the generation of three-dimensional fruiting bodies in filamentous fungi like Sordaria macrospora. Fruiting body development is controlled by subunits of the highly conserved striatin-interacting phosphatase and kinase (STRIPAK complex, which has been described in organisms ranging from yeasts to humans. The highly conserved heterotrimeric protein phosphatase PP2A is a subunit of STRIPAK. Here, catalytic subunit 1 of PP2A was functionally characterized. The Δpp2Ac1 strain is sterile, unable to undergo hyphal fusion, and devoid of ascogonial septation. Further, PP2Ac1, together with STRIPAK subunit PRO22, governs vegetative and stress-related growth. We revealed in vitro catalytic activity of wild-type PP2Ac1, and our in vivo analysis showed that inactive PP2Ac1 blocks the complementation of the sterile deletion strain. Tandem affinity purification, followed by mass spectrometry and yeast two-hybrid analysis, verified that PP2Ac1 is a subunit of STRIPAK. Further, these data indicate links between the STRIPAK complex and other developmental signaling pathways, implying the presence of a large interconnected signaling network that controls eukaryotic developmental processes. The insights gained in our study can be transferred to higher eukaryotes and will be important for understanding eukaryotic cellular development in general.

  7. 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 parameter...

  8. Multiple isoforms for the catalytic subunit of PKA in the basal fungal lineage Mucor circinelloides.

    Science.gov (United States)

    Fernández Núñez, Lucas; Ocampo, Josefina; Gottlieb, Alexandra M; Rossi, Silvia; Moreno, Silvia

    2016-12-01

    Protein kinase A (PKA) activity is involved in dimorphism of the basal fungal lineage Mucor. From the recently sequenced genome of Mucor circinelloides we could predict ten catalytic subunits of PKA. From sequence alignment and structural prediction we conclude that the catalytic core of the isoforms is conserved, and the difference between them resides in their amino termini. This high number of isoforms is maintained in the subdivision Mucoromycotina. Each paralogue, when compared to the ones form other fungi is more homologous to one of its orthologs than to its paralogs. All of these fungal isoforms cannot be included in the class I or II in which fungal protein kinases have been classified. mRNA levels for each isoform were measured during aerobic and anaerobic growth. The expression of each isoform is differential and associated to a particular growth stage. We reanalyzed the sequence of PKAC (GI 20218944), the only cloned sequence available until now for a catalytic subunit of M. circinelloides. PKAC cannot be classified as a PKA because of its difference in the conserved C-tail; it shares with PKB a conserved C2 domain in the N-terminus. No catalytic activity could be measured for this protein nor predicted bioinformatically. It can thus be classified as a pseudokinase. Its importance can not be underestimated since it is expressed at the mRNA level in different stages of growth, and its deletion is lethal. Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  9. Power reactor information system (PRIS)

    International Nuclear Information System (INIS)

    1989-06-01

    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

  10. Power Reactor Information System (PRIS)

    International Nuclear Information System (INIS)

    Spiegelberg, R.

    1992-01-01

    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.)

  11. Involvement of the catalytic subunit of protein kinase A and of HA95 in pre-mRNA splicing

    International Nuclear Information System (INIS)

    Kvissel, Anne-Katrine; Orstavik, Sigurd; Eikvar, Sissel; Brede, Gaute; Jahnsen, Tore; Collas, Philippe; Akusjaervi, Goeran; Skalhegg, Bjorn Steen

    2007-01-01

    Protein kinase A (PKA) is a holoenzyme consisting of two catalytic (C) subunits bound to a regulatory (R) subunit dimer. Stimulation by cAMP dissociates the holoenzyme and causes translocation to the nucleus of a fraction of the C subunit. Apart from transcription regulation, little is known about the function of the C subunit in the nucleus. In the present report, we show that both Cα and Cβ are localized to spots in the mammalian nucleus. Double immunofluorescence analysis of splicing factor SC35 with the C subunit indicated that these spots are splicing factor compartments (SFCs). Using the E1A in vivo splicing assay, we found that catalytically active C subunits regulate alternative splicing and phosphorylate several members of the SR-protein family of splicing factors in vitro. Furthermore, nuclear C subunits co-localize with the C subunit-binding protein homologous to AKAP95, HA95. HA95 also regulates E1A alternative splicing in vivo, apparently through its N-terminal domain. Localization of the C subunit to SFCs and the E1A splicing pattern were unaffected by cAMP stimulation. Our findings demonstrate that the nuclear PKA C subunit co-locates with HA95 in SFCs and regulates pre-mRNA splicing, possibly through a cAMP-independent mechanism

  12. PKA catalytic subunit compartmentation regulates contractile and hypertrophic responses to β-adrenergic signaling

    Science.gov (United States)

    Yang, Jason H.; Polanowska-Grabowska, Renata K.; Smith, Jeffrey S.; Shields, Charles W.; Saucerman, Jeffrey J.

    2014-01-01

    β-adrenergic signaling is spatiotemporally heterogeneous in the cardiac myocyte, conferring exquisite control to sympathetic stimulation. Such heterogeneity drives the formation of protein kinase A (PKA) signaling microdomains, which regulate Ca2+ handling and contractility. Here, we test the hypothesis that the nucleus independently comprises a PKA signaling microdomain regulating myocyte hypertrophy. Spatially-targeted FRET reporters for PKA activity identified slower PKA activation and lower isoproterenol sensitivity in the nucleus (t50 = 10.60±0.68 min; EC50 = 89.00 nmol/L) than in the cytosol (t50 = 3.71±0.25 min; EC50 = 1.22 nmol/L). These differences were not explained by cAMP or AKAP-based compartmentation. A computational model of cytosolic and nuclear PKA activity was developed and predicted that differences in nuclear PKA dynamics and magnitude are regulated by slow PKA catalytic subunit diffusion, while differences in isoproterenol sensitivity are regulated by nuclear expression of protein kinase inhibitor (PKI). These were validated by FRET and immunofluorescence. The model also predicted differential phosphorylation of PKA substrates regulating cell contractility and hypertrophy. Ca2+ and cell hypertrophy measurements validated these predictions and identified higher isoproterenol sensitivity for contractile enhancements (EC50 = 1.84 nmol/L) over cell hypertrophy (EC50 = 85.88 nmol/L). Over-expression of spatially targeted PKA catalytic subunit to the cytosol or nucleus enhanced contractile and hypertrophic responses, respectively. We conclude that restricted PKA catalytic subunit diffusion is an important PKA compartmentation mechanism and the nucleus comprises a novel PKA signaling microdomain, insulating hypertrophic from contractile β-adrenergic signaling responses. PMID:24225179

  13. Evolution of the cAMP-dependent protein kinase (PKA catalytic subunit isoforms.

    Directory of Open Access Journals (Sweden)

    Kristoffer Søberg

    Full Text Available The 3',5'-cyclic adenosine monophosphate (cAMP-dependent protein kinase, or protein kinase A (PKA, pathway is one of the most versatile and best studied signaling pathways in eukaryotic cells. The two paralogous PKA catalytic subunits Cα and Cβ, encoded by the genes PRKACA and PRKACB, respectively, are among the best understood model kinases in signal transduction research. In this work, we explore and elucidate the evolution of the alternative 5' exons and the splicing pattern giving rise to the numerous PKA catalytic subunit isoforms. In addition to the universally conserved Cα1/Cβ1 isoforms, we find kinase variants with short N-termini in all main vertebrate classes, including the sperm-specific Cα2 isoform found to be conserved in all mammals. We also describe, for the first time, a PKA Cα isoform with a long N-terminus, paralogous to the PKA Cβ2 N-terminus. An analysis of isoform-specific variation highlights residues and motifs that are likely to be of functional importance.

  14. Evolutionary Paths of the cAMP-Dependent Protein Kinase (PKA) Catalytic Subunits

    Science.gov (United States)

    Søberg, Kristoffer; Jahnsen, Tore; Rognes, Torbjørn; Skålhegg, Bjørn S.; Laerdahl, Jon K.

    2013-01-01

    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. PMID:23593352

  15. PRKACA: the catalytic subunit of protein kinase A and adrenocortical tumors

    Directory of Open Access Journals (Sweden)

    Annabel Sophie Berthon

    2015-05-01

    Full Text Available Cyclic-AMP (cAMP-dependent protein kinase (PKA is the main effector of cAMP signaling in all tissues. Inactivating mutations of the PRKAR1A gene, coding for the type 1A regulatory subunit of PKA, are responsible for Carney complex and primary pigmented nodular adrenocortical disease (PPNAD. PRKAR1A inactivation and PKA dysregulation have been implicated in various types of adrenocortical pathologies associated with ACTH-independent Cushing syndrome (AICS from PPNAD to adrenocortical adenomas and cancer, and other forms of bilateral adrenocortical hyperplasias (BAH. More recently, mutations of PRKACA, the gene coding for the catalytic subunit C alpha (Cα, were also identified in the pathogenesis of adrenocortical tumors. PRKACA copy number gain was found in the germline of several patients with cortisol-producing BAH, whereas the somatic Leu206Arg (c.617A>C recurrent PRKACA mutation was found in as many as half of all adrenocortical adenomas associated with AICS. In vitro analysis demonstrated that this mutation led to constitutive Cα activity, unregulated by its main partners, the PKA regulatory subunits. In this review, we summarize the current understanding of the involvement of PRKACA in adrenocortical tumorigenesis, and our understanding of PKA’s role in adrenocortical lesions. We also discuss potential therapeutic advances that can be made through targeting of PRKACA and the PKA pathway.

  16. 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.

  17. Overexpression of PP2A-C5 that encodes the catalytic subunit 5 of protein phosphatase 2A in Arabidopsis confers better root and shoot development under salt conditions

    Science.gov (United States)

    Protein phosphatase 2A (PP2A) is an enzyme consisting of three subunits: a scaffolding A subunit, a regulatory B subunit and a catalytic C subunit. PP2As were shown to play diverse roles in eukaryotes. In this study, the function of the Arabidopsis PP2A-C5 gene that encodes the catalytic subunit 5 o...

  18. Liberated PKA Catalytic Subunits Associate with the Membrane via Myristoylation to Preferentially Phosphorylate Membrane Substrates.

    Science.gov (United States)

    Tillo, Shane E; Xiong, Wei-Hong; Takahashi, Maho; Miao, Sheng; Andrade, Adriana L; Fortin, Dale A; Yang, Guang; Qin, Maozhen; Smoody, Barbara F; Stork, Philip J S; Zhong, Haining

    2017-04-18

    Protein kinase A (PKA) has diverse functions in neurons. At rest, the subcellular localization of PKA is controlled by A-kinase anchoring proteins (AKAPs). However, the dynamics of PKA upon activation remain poorly understood. Here, we report that elevation of cyclic AMP (cAMP) in neuronal dendrites causes a significant percentage of the PKA catalytic subunit (PKA-C) molecules to be released from the regulatory subunit (PKA-R). Liberated PKA-C becomes associated with the membrane via N-terminal myristoylation. This membrane association does not require the interaction between PKA-R and AKAPs. It slows the mobility of PKA-C and enriches kinase activity on the membrane. Membrane-residing PKA substrates are preferentially phosphorylated compared to cytosolic substrates. Finally, the myristoylation of PKA-C is critical for normal synaptic function and plasticity. We propose that activation-dependent association of PKA-C renders the membrane a unique PKA-signaling compartment. Constrained mobility of PKA-C may synergize with AKAP anchoring to determine specific PKA function in neurons. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

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

    International Nuclear Information System (INIS)

    2015-01-01

    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

  20. 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 ...

  1. The PKA-C3 catalytic subunit is required in two pairs of interneurons for successful mating of Drosophila.

    Science.gov (United States)

    Cassar, Marlène; Sunderhaus, Elizabeth; Wentzell, Jill S; Kuntz, Sara; Strauss, Roland; Kretzschmar, Doris

    2018-02-06

    Protein kinase A (PKA) has been shown to play a role in a plethora of cellular processes ranging from development to memory formation. Its activity is mediated by the catalytic subunits whereby many species express several paralogs. Drosophila encodes three catalytic subunits (PKA-C1-3) and whereas PKA-C1 has been well studied, the functions of the other two subunits were unknown. PKA-C3 is the orthologue of mammalian PRKX/Pkare and they are structurally more closely related to each other than to other catalytic subunits within their species. PRKX is expressed in the nervous system in mice but its function is also unknown. We now show that the loss of PKA-C3 in Drosophila causes copulation defects, though the flies are active and show no defects in other courtship behaviours. This phenotype is specifically due to the loss of PKA-C3 because PKA-C1 cannot replace PKA-C3. PKA-C3 is expressed in two pairs of interneurons that send projections to the ventro-lateral protocerebrum and the mushroom bodies and that synapse onto motor neurons in the ventral nerve cord. Rescue experiments show that expression of PKA-C3 in these interneurons is sufficient for copulation, suggesting a role in relaying information from the sensory system to motor neurons to initiate copulation.

  2. Organization and alternative splicing of the Caenorhabditis elegans cAMP-dependent protein kinase catalytic-subunit gene (kin-1).

    Science.gov (United States)

    Tabish, M; Clegg, R A; Rees, H H; Fisher, M J

    1999-04-01

    The cAMP-dependent protein kinase (protein kinase A, PK-A) is multifunctional in nature, with key roles in the control of diverse aspects of eukaryotic cellular activity. In the case of the free-living nematode, Caenorhabditis elegans, a gene encoding the PK-A catalytic subunit has been identified and two isoforms of this subunit, arising from a C-terminal alternative-splicing event, have been characterized [Gross, Bagchi, Lu and Rubin (1990) J. Biol. Chem. 265, 6896-6907]. Here we report the occurrence of N-terminal alternative-splicing events that, in addition to generating a multiplicity of non-myristoylatable isoforms, also generate the myristoylated variant(s) of the catalytic subunit that we have recently characterized [Aspbury, Fisher, Rees and Clegg (1997) Biochem. Biophys. Res. Commun. 238, 523-527]. The gene spans more than 36 kb and is divided into a total of 13 exons. Each of the mature transcripts contains only 7 exons. In addition to the already characterized exon 1, the 5'-untranslated region and first intron actually contain 5 other exons, any one of which may be alternatively spliced on to exon 2 at the 5' end of the pre-mRNA. This N-terminal alternative splicing occurs in combination with either of the already characterized C-terminal alternative exons. Thus, C. elegans expresses at least 12 different isoforms of the catalytic subunit of PK-A. The significance of this unprecedented structural diversity in the family of PK-A catalytic subunits is discussed.

  3. Improved crystallization of Escherichia coli ATP synthase catalytic complex (F1) by introducing a phosphomimetic mutation in subunit

    International Nuclear Information System (INIS)

    Roy, Ankoor; Hutcheon, Marcus L.; Duncan, Thomas M.; Cingolani, Gino

    2012-01-01

    A phosphomimetic mutation in subunit ∊ dramatically increases reproducibility for crystallization of Escherichia coli ATP synthase catalytic complex (F 1 ) (subunit composition α 3 β 3 γ∊). Diffraction data were collected to ∼3.15 Å resolution using synchrotron radiation. The bacterial ATP synthase (F O F 1 ) of Escherichia coli has been the prominent model system for genetics, biochemical and more recently single-molecule studies on F-type ATP synthases. With 22 total polypeptide chains (total mass of ∼529 kDa), E. coli F O F 1 represents nature’s smallest rotary motor, composed of a membrane-embedded proton transporter (F O ) and a peripheral catalytic complex (F 1 ). The ATPase activity of isolated F 1 is fully expressed by the α 3 β 3 γ ‘core’, whereas single δ and ∊ subunits are required for structural and functional coupling of E. coli F 1 to F O . In contrast to mitochondrial F 1 -ATPases that have been determined to atomic resolution, the bacterial homologues have proven very difficult to crystallize. In this paper, we describe a biochemical strategy that led us to improve the crystallogenesis of the E. coli F 1 -ATPase catalytic core. Destabilizing the compact conformation of ∊’s C-terminal domain with a phosphomimetic mutation (∊S65D) dramatically increased crystallization success and reproducibility, yielding crystals of E. coli F 1 that diffract to ∼3.15 Å resolution

  4. Comparison of the kinetic parameters of the truncated catalytic subunit and holoenzyme of human DNA polymerase ε

    Science.gov (United States)

    Zahurancik, Walter J.; Baranovskiy, Andrey G.; Tahirov, Tahir H.; Suo, Zucai

    2015-01-01

    Numerous genetic studies have provided compelling evidence to establish DNA polymerase ε (Polε) as the primary DNA polymerase responsible for leading strand synthesis during eukaryotic nuclear genome replication. Polε is a heterotetramer consisting of a large catalytic subunit that contains the conserved polymerase core domain as well as a 3′ → 5′ exonuclease domain common to many replicative polymerases. In addition, Polε possesses three small subunits that lack a known catalytic activity but associate with components involved in a variety of DNA replication and maintenance processes. Previous enzymatic characterization of the Polε heterotetramer from budding yeast suggested that the small subunits slightly enhance DNA synthesis by Polε in vitro. However, similar studies of the human Polε heterote-tramer (hPolε) have been limited by the difficulty of obtaining hPolε in quantities suitable for thorough investigation of its catalytic activity. Utilization of a baculovirus expression system for overexpression and purification of hPolε from insect host cells has allowed for isolation of greater amounts of active hPolε, thus enabling a more detailed kinetic comparison between hPolε and an active N-terminal fragment of the hPolε catalytic subunit (p261N), which is readily overexpressed in Escherichia coli. Here, we report the first pre-steady-state studies of fully-assembled hPolε. We observe that the small subunits increase DNA binding by hPolε relative to p261N, but do not increase processivity during DNA synthesis on a single-stranded M13 template. Interestingly, the 3′ → 5′ exonuclease activity of hPolε is reduced relative to p261N on matched and mismatched DNA substrates, indicating that the presence of the small subunits may regulate the proofreading activity of hPolε and sway hPolε toward DNA synthesis rather than proofreading. PMID:25684708

  5. Exercise induced upregulation of glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modifier subunit gene expression in Thoroughbred horses

    Directory of Open Access Journals (Sweden)

    Jeong-Woong Park

    2017-05-01

    Full Text Available Objective This study was performed to reveal the molecular structure and expression patterns of horse glutamate-cysteine ligase catalytic subunit (GCLC and glutamate-cysteine ligase modifier subunit (GCLM genes whose products form glutamate cysteine ligase, which were identified as differentially expressed genes in the previous study. Methods We performed bioinformatics analyses, and gene expression assay with quantitative polymerase chain reaction (qPCR for horse GCLC and GCLM genes in muscle and blood leukocytes of Thoroughbred horses Results Expression of GCLC showed the same pattern in both blood and muscle tissues after exercise. Expression of GCLC increased in the muscle and blood of Thoroughbreds, suggesting a tissue-specific regulatory mechanism for the expression of GCLC. In addition, expression of the GCLM gene increased after exercise in both the blood and muscle of Thoroughbreds. Conclusion We established the expression patterns of GCLC and GCLM in the skeletal muscle and blood of Thoroughbred horses in response to exercise. Further study is now warranted to uncover the functional importance of these genes in exercise and recovery in racehorses.

  6. PC version of PRIS (Power Reactor Information System)

    International Nuclear Information System (INIS)

    Fukala, J.; Stanik, Z.; White, D.

    1990-05-01

    The IAEA has been collecting operating experience data on nuclear power plants in the Member States since 1970. In 1980 a computerized database was established, the IAEA Power Reactor Information System (PRIS). To make PRIS data available to the Member States in a more convenient format, the development of a PC version of PRIS started in 1989

  7. 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?

  8. The IAEA power reactor information system - PRIS

    International Nuclear Information System (INIS)

    Laue, H.J.; Qureshi, A.; Skjoeldebrand, R.; White, D.

    1983-01-01

    The IAEA Power Reactor Information System, PRIS, is based on a collection of basic design data and operating experience data which the IAEA started in 1970. PRIS is used for annual publications on 'Power Reactors in Member States', 'Operating Experience with Nuclear Power Stations in Member States', which gives annual operating information for individual plants, and a 'Performance Analysis Report' summarizing each year's and earlier experience. Since 1973 information has been collected in a systematic manner on significant plant outages (= more than 10 full power hours). There is now information on more than 10,000 outages in the system which permits some conclusions to be drawn both in regard to individual plants and to categories of plants on the significance of different outage reasons and different types of equipment failures. PRIS has not been intended to be a component reliability information system as an international data collection must stop short of the level of detail which would be needed for that purpose. The objectives of PRIS have been to provide a factual background for assumptions on parameters which are essential for economic evaluations and for systems operation planning (load factor and availability). The outage information does, however, lend itself to conclusions about generic problems in different categories of plants and it can be used by an individual operator to find other plants where information about particular problems can be obtained. It would also now be possible to use PRIS for setting availability goals based on experience and not only on theoretical design considerations. The paper demonstrates the conclusions which can be drawn from 662 reactor years of operation of light and heavy water pressurized reactors and 390 reactor years of boiling water reactors and, in particular, the role that the main heat removal system and its components have played in the equipment failure category

  9. Interaction mode between catalytic and regulatory subunits in glucosidase II involved in ER glycoprotein quality control.

    Science.gov (United States)

    Satoh, Tadashi; Toshimori, Takayasu; Noda, Masanori; Uchiyama, Susumu; Kato, Koichi

    2016-11-01

    The glycoside hydrolase family 31 (GH31) α-glucosidases play vital roles in catabolic and regulated degradation, including the α-subunit of glucosidase II (GIIα), which catalyzes trimming of the terminal glucose residues of N-glycan in glycoprotein processing coupled with quality control in the endoplasmic reticulum (ER). Among the known GH31 enzymes, only GIIα functions with its binding partner, regulatory β-subunit (GIIβ), which harbors a lectin domain for substrate recognition. Although the structural data have been reported for GIIα and the GIIβ lectin domain, the interaction mode between GIIα and GIIβ remains unknown. Here, we determined the structure of a complex formed between GIIα and the GIIα-binding domain of GIIβ, thereby providing a structural basis underlying the functional extension of this unique GH31 enzyme. © 2016 The Protein Society.

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

    International Nuclear Information System (INIS)

    Arino, J.; Woon, Chee Wai; Brautigan, D.L.; Miller, T.B. Jr.; Johnson, G.L.

    1988-01-01

    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

  11. Identification of the segment of the catalytic subunit of (Na+,K+)ATPase containing the digitalis binding site.

    Science.gov (United States)

    Rossi, B; Ponzio, G; Lazdunski, M

    1982-01-01

    Digitalis compounds that are extensively used in the treatment of cardiovascular disorders are known to bind specifically at the extracellular side of (Na+,K+)ATPase. We have recently reported the synthesis of [3H]p- nitrophenyltriazene -ouabain, a derivative of ouabain, which specifically alkylates the catalytic chain of the (Na+,K+)ATPase at a defined region of the sequence. The peptidic segment involved in the binding of digitalis to (Na+,K+)ATPase has been located after mild trypsin treatment of the labeled enzyme. In the presence of 100 mM KCl, tryptic fragmentation results in two peptide fragments of mol. wt. 58 000 and 41 000, respectively. The radioactive probe labeled only the 41 000 fragment indicating that the digitalis binding site is located on the 41 000 domain situated at the N-terminal part of the sequence of the alpha-subunit. Images Fig. 1. Fig. 3. PMID:6329711

  12. Identification of aspartate-184 as an essential residue in the catalytic subunit of cAMP-dependent protein kinase

    International Nuclear Information System (INIS)

    Buechler, J.A.; Taylor, S.S.

    1988-01-01

    The hydrophobic carbodiimide dicyclohexylcarbodiimide (DCCD) was previously shown to be an irreversible inhibitor of the catalytic subunit of cAMP-dependent protein kinase, and MgATP protected against inactivation. This inhibition by DCCD indicated that an essential carboxyl group was present at the active site of the enzyme even though identification of that carboxyl group was not possible. This presumably was because a nucleophile on the protein cross-linked to the electrophilic intermediate formed when the carbodiimide reacted with the carboxyl group. To circumvent this problem, the catalytic subunit first was treated with acetic anhydride to block accessible lysine residues, thus preventing intramolecular cross-linking. The DCCD reaction then was carried out in the presence of [ 14 C]glycine ethyl ester in order to trap any electrophilic intermediates that were generated by DCCD. The modified protein was treated with trypsin, and the resulting peptides were separated by HPLC. Two major radioactive peptides were isolated as well as one minor peptide. MgATP protected all three peptides from covalent modification. The two major peaks contained the same modified carboxyl group, which corresponded to Asp-184. The minor peak contained a modified glutamic acid, Glu-91. Both of these acidic residues are conserved in all protein kinases, which is consistent with their playing essential roles. The positions of Asp-184 and Glu-91 have been correlated with the overall domain structure of the molecule. Asp-184 may participate as a general base catalyst at the active site. A third carboxyl group, Glu-230, also was identified

  13. Isolation of a candidate human telomerase catalytic subunit gene, which reveals complex splicing patterns in different cell types.

    Science.gov (United States)

    Kilian, A; Bowtell, D D; Abud, H E; Hime, G R; Venter, D J; Keese, P K; Duncan, E L; Reddel, R R; Jefferson, R A

    1997-11-01

    Telomerase is a multicomponent reverse transcriptase enzyme that adds DNA repeats to the ends of chromosomes using its RNA component as a template for synthesis. Telomerase activity is detected in the germline as well as the majority of tumors and immortal cell lines, and at low levels in several types of normal cells. We have cloned a human gene homologous to a protein from Saccharomyces cerevisiae and Euplotes aediculatus that has reverse transcriptase motifs and is thought to be the catalytic subunit of telomerase in those species. This gene is present in the human genome as a single copy sequence with a dominant transcript of approximately 4 kb in a human colon cancer cell line, LIM1215. The cDNA sequence was determined using clones from a LIM1215 cDNA library and by RT-PCR, cRACE and 3'RACE on mRNA from the same source. We show that the gene is expressed in several normal tissues, telomerase-positive post-crisis (immortal) cell lines and various tumors but is not expressed in the majority of normal tissues analyzed, pre-crisis (non-immortal) cells and telomerase-negative immortal (ALT) cell lines. Multiple products were identified by RT-PCR using primers within the reverse transcriptase domain. Sequencing of these products suggests that they arise by alternative splicing. Strikingly, various tumors, cell lines and even normal tissues (colonic crypt and testis) showed considerable differences in the splicing patterns. Alternative splicing of the telomerase catalytic subunit transcript may be important for the regulation of telomerase activity and may give rise to proteins with different biochemical functions.

  14. Identification of a third form of NaK-ATPase catalytic subunit in rat brain by photoaffinity labeling

    International Nuclear Information System (INIS)

    Lowndes, J.M.; Millan, N.M.; Ruoho, A.E.; Hokin-Neaverson, M.

    1987-01-01

    Using photoaffinity labeling, they have found a form of the NaK-ATPase catalytic subunit, α(-), in the rat brain that is distinct from the α and α(+) forms. Strong radiolabeling of α(-) was obtained with [ 125 I]azido-iodophenethylamido-succinyl-cymarin (AISC). AISC is a new cardiotonic steroid photolabel which they have synthesized and characterized chemically and biochemically. This compound labels α(-) better than the photolabels that they have previously reported. SDS-PAGE (5%) of photolabeled rat brain microsomes showed that α(-) migrated with faster mobility than the dog kidney α subunit. The α(-) appears to have different specificity for different cardiotonic steroids than either α(+) or α. The radiolabeling of rat brain α(+) and dog kidney α with [ 125 I]AISC was protectable by ouabain; in contrast, 1 mM ouabain did not reduce the [ 125 I]AISC-labeling of α(-), although the labeling was protected with 200 μM cymarin or AISC. The results indicate that the α(-) form of the NaK-ATPase in rat brain binds cymarin and its derivative but has little affinity for ouabain. It is possible that α(-) may be the translation product of the rat brain α(III) mRNA which has recently been described

  15. Estado e controle nas prisões

    OpenAIRE

    Batista, Analía Soria

    2009-01-01

    Este artigo analisa o problema da produção do controle e da ordem em prisões brasileiras, utilizando as perspectivas histórica e sociológica, e levanta a hipóteses de que, no Brasil, convivem duas modalidades de construção da ordem e do controle nas prisões. Uma delas, minoritária, baseia-se na prerrogativa do Estado na gestão do dia a dia prisional. A outra é relativa à negociação da pacificação do presídio entre o Estado e as lideranças dos presos. Embora, no primeiro caso, a prerrogativa d...

  16. The catalytic subunit of human protein kinase CK2 structurally deviates from its maize homologue in complex with the nucleotide competitive inhibitor emodin

    DEFF Research Database (Denmark)

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

    2008-01-01

    The Ser/Thr kinase CK2 (former name: casein kinase 2) is a heterotetrameric enzyme composed of two catalytic chains (CK2alpha) attached to a dimer of noncatalytic subunits. Together with the cyclin-dependent kinases and the mitogen-activated protein kinases, CK2alpha belongs to the CMGC family of...

  17. 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)

    Morales-Ríos, Edgar; Montgomery, Martin G.; Leslie, Andrew G. W.; García-Trejo, José J.; Walker, John E.

    2015-01-01

    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 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 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

  18. 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.

  19. The minimum activation peptide from ilvH can activate the catalytic subunit of AHAS from different species.

    Science.gov (United States)

    Zhao, Yuefang; Niu, Congwei; Wen, Xin; Xi, Zhen

    2013-04-15

    Acetohydroxyacid synthases (AHASs), which catalyze the first step in the biosynthesis of branched-chain amino acids, are composed of a catalytic subunit (CSU) and a regulatory subunit (RSU). The CSU harbors the catalytic site, and the RSU is responsible for the activation and feedback regulation of the CSU. Previous results from Chipman and co-workers and our lab have shown that heterologous activation can be achieved among isozymes of Escherichia coli AHAS. It would be interesting to find the minimum peptide of ilvH (the RSU of E. coli AHAS III) that could activate other E. coli CSUs, or even those of ## species. In this paper, C-terminal, N-terminal, and C- and N-terminal truncation mutants of ilvH were constructed. The minimum peptide to activate ilvI (the CSU of E. coli AHAS III) was found to be ΔN 14-ΔC 89. Moreover, this peptide could not only activate its homologous ilvI and heterologous ilvB (CSU of E. coli AHAS I), but also heterologously activate the CSUs of AHAS from Saccharomyces cerevisiae, Arabidopsis thaliana, and Nicotiana plumbaginifolia. However, this peptide totally lost its ability for feedback regulation by valine, thus suggesting different elements for enzymatic activation and feedback regulation. Additionally, the apparent dissociation constant (Kd ) of ΔN 14-ΔC 89 when binding CSUs of different species was found to be 9.3-66.5 μM by using microscale thermophoresis. The ability of this peptide to activate different CSUs does not correlate well with its binding ability (Kd ) to these CSUs, thus implying that key interactions by specific residues is more important than binding ability in promoting enzymatic reactions. The high sequence similarity of the peptide ΔN 14-ΔC 89 to RSUs across species hints that this peptide represents the minimum activation motif in RSU and that it regulates all AHASs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Estado e controle nas prisões

    Directory of Open Access Journals (Sweden)

    Analía Soria Batista

    Full Text Available Este artigo analisa o problema da produção do controle e da ordem em prisões brasileiras, utilizando as perspectivas histórica e sociológica, e levanta a hipóteses de que, no Brasil, convivem duas modalidades de construção da ordem e do controle nas prisões. Uma delas, minoritária, baseia-se na prerrogativa do Estado na gestão do dia a dia prisional. A outra é relativa à negociação da pacificação do presídio entre o Estado e as lideranças dos presos. Embora, no primeiro caso, a prerrogativa do Estado possa ser vinculada às condições institucionais adequadas e, no segundo (negociação entre o estado e as lideranças dos presos às condições precárias dos presídios, como superlotação, número reduzido de agentes penitenciários, entre outros, a análise apontou que ambas as modalidades traduzem formas de relacionamentos e interações sociais historicamente produzidas entre o Estado e a sociedade, que remetem à fundação da República, recriadas através do habitus dos atores sociais, não se restringindo exclusivamente ao espaço social das prisões.

  1. O-GlcNAcylation modulates PKA-CREB signaling in a manner specific to PKA catalytic subunit isoforms.

    Science.gov (United States)

    Jin, Nana; Ma, Denglei; Gu, Jianlan; Shi, Jianhua; Xu, Xiaotao; Iqbal, Khalid; Gong, Cheng-Xin; Liu, Fei; Chu, Dandan

    2018-02-26

    O-GlcNAcylation is a post-translational modification of proteins. Protein kinase A (PKA)-cAMP response element binding protein (CREB) signaling plays critical roles in multiple biological processes. Isoforms α and β of PKA catalytic subunit (PKAc) and CREB are modified by O-GlcNAcylation. In the present study, we determined the role of O-GlcNAcylation in PKAc isoform-specific CREB signaling. We found that up-regulation of O-GlcNAcylation enhanced CREB phosphorylation, but suppressed CREB expression in exogenous PKAc isoform-unspecific manner. PKAc isoforms affected exogenous expression of OGT or OGA and protein O-GlcNAcylation differently. Up-regulation of O-GlcNAcylation did not significantly affect net PKAcα-CREB signaling, but enhanced PKAcβ-CREB signaling. The role of O-GlcNAcylation in PKA-CREB signaling was desensitized by insulin treatment. This study suggests a role of O-GlcNAcylation in PKA-CREB signaling by affecting phosphorylation of CREB in a PKAc isoform-specific manner. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. Phosphorylation of the protein kinase A catalytic subunit is induced by cyclic AMP deficiency and physiological stresses in the fission yeast, Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    McInnis, Brittney; Mitchell, Jessica; Marcus, Stevan

    2010-01-01

    Research highlights: → cAMP deficiency induces phosphorylation of PKA catalytic subunit (Pka1) in S. pombe. → Pka1 phosphorylation is further induced by physiological stresses. → Pka1 phosphorylation is not induced in cells lacking the PKA regulatory subunit. → Results suggest that cAMP-independent Pka1 phosphorylation is stimulatory in nature. -- Abstract: In the fission yeast, Schizosaccharomyces pombe, cyclic AMP (cAMP)-dependent protein kinase (PKA) is not essential for viability under normal culturing conditions, making this organism attractive for investigating mechanisms of PKA regulation. Here we show that S. pombe cells carrying a deletion in the adenylate cyclase gene, cyr1, express markedly higher levels of the PKA catalytic subunit, Pka1, than wild type cells. Significantly, in cyr1Δ cells, but not wild type cells, a substantial proportion of Pka1 protein is hyperphosphorylated. Pka1 hyperphosphorylation is strongly induced in cyr1Δ cells, and to varying degrees in wild type cells, by both glucose starvation and stationary phase stresses, which are associated with reduced cAMP-dependent PKA activity, and by KCl stress, the cellular adaptation to which is dependent on PKA activity. Interestingly, hyperphosphorylation of Pka1 was not detected in either cyr1 + or cyr1Δ S. pombe strains carrying a deletion in the PKA regulatory subunit gene, cgs1, under any of the tested conditions. Our results demonstrate the existence of a cAMP-independent mechanism of PKA catalytic subunit phosphorylation, which we propose could serve as a mechanism for inducing or maintaining specific PKA functions under conditions in which its cAMP-dependent activity is downregulated.

  3. Identification of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) as a novel target of bisphenol A.

    Science.gov (United States)

    Ito, Yuki; Ito, Takumi; Karasawa, Satoki; Enomoto, Teruya; Nashimoto, Akihiro; Hase, Yasuyoshi; Sakamoto, Satoshi; Mimori, Tsuneyo; Matsumoto, Yoshihisa; Yamaguchi, Yuki; Handa, Hiroshi

    2012-01-01

    Bisphenol A (BPA) forms the backbone of plastics and epoxy resins used to produce packaging for various foods and beverages. BPA is also an estrogenic disruptor, interacting with human estrogen receptors (ER) and other related nuclear receptors. Nevertheless, the effects of BPA on human health remain unclear. The present study identified DNA-dependent protein kinase catalytic subunit (DNA-PKcs) as a novel BPA-binding protein. DNA-PKcs, in association with the Ku heterodimer (Ku70/80), is a critical enzyme involved in the repair of DNA double-strand breaks. Low levels of DNA-PK activity are previously reported to be associated with an increased risk of certain types of cancer. Although the Kd for the interaction between BPA and a drug-binding mutant of DNA-PKcs was comparatively low (137 nM), high doses of BPA were required before cellular effects were observed (100-300 μM). The results of an in vitro kinase assay showed that BPA inhibited DNA-PK kinase activity in a concentration-dependent manner. In M059K cells, BPA inhibited the phosphorylation of DNA-PKcs at Ser2056 and H2AX at Ser139 in response to ionizing radiation (IR)-irradiation. BPA also disrupted DNA-PKcs binding to Ku70/80 and increased the radiosensitivity of M059K cells, but not M059J cells (which are DNA-PKcs-deficient). Taken together, these results provide new evidence of the effects of BPA on DNA repair in mammalian cells, which are mediated via inhibition of DNA-PK activity. This study may warrant the consideration of the possible carcinogenic effects of high doses of BPA, which are mediated through its action on DNA-PK.

  4. daf-31 encodes the catalytic subunit of N alpha-acetyltransferase that regulates Caenorhabditis elegans development, metabolism and adult lifespan.

    Directory of Open Access Journals (Sweden)

    Di Chen

    2014-10-01

    Full Text Available The Caenorhabditis elegans dauer larva is a facultative state of diapause. Mutations affecting dauer signal transduction and morphogenesis have been reported. Of these, most that result in constitutive formation of dauer larvae are temperature-sensitive (ts. The daf-31 mutant was isolated in genetic screens looking for novel and underrepresented classes of mutants that form dauer and dauer-like larvae non-conditionally. Dauer-like larvae are arrested in development and have some, but not all, of the normal dauer characteristics. We show here that daf-31 mutants form dauer-like larvae under starvation conditions but are sensitive to SDS treatment. Moreover, metabolism is shifted to fat accumulation in daf-31 mutants. We cloned the daf-31 gene and it encodes an ortholog of the arrest-defective-1 protein (ARD1 that is the catalytic subunit of the major N alpha-acetyltransferase (NatA. A daf-31 promoter::GFP reporter gene indicates daf-31 is expressed in multiple tissues including neurons, pharynx, intestine and hypodermal cells. Interestingly, overexpression of daf-31 enhances the longevity phenotype of daf-2 mutants, which is dependent on the forkhead transcription factor (FOXO DAF-16. We demonstrate that overexpression of daf-31 stimulates the transcriptional activity of DAF-16 without influencing its subcellular localization. These data reveal an essential role of NatA in controlling C. elegans life history and also a novel interaction between ARD1 and FOXO transcription factors, which may contribute to understanding the function of ARD1 in mammals.

  5. daf-31 encodes the catalytic subunit of N alpha-acetyltransferase that regulates Caenorhabditis elegans development, metabolism and adult lifespan.

    Science.gov (United States)

    Chen, Di; Zhang, Jiuli; Minnerly, Justin; Kaul, Tiffany; Riddle, Donald L; Jia, Kailiang

    2014-10-01

    The Caenorhabditis elegans dauer larva is a facultative state of diapause. Mutations affecting dauer signal transduction and morphogenesis have been reported. Of these, most that result in constitutive formation of dauer larvae are temperature-sensitive (ts). The daf-31 mutant was isolated in genetic screens looking for novel and underrepresented classes of mutants that form dauer and dauer-like larvae non-conditionally. Dauer-like larvae are arrested in development and have some, but not all, of the normal dauer characteristics. We show here that daf-31 mutants form dauer-like larvae under starvation conditions but are sensitive to SDS treatment. Moreover, metabolism is shifted to fat accumulation in daf-31 mutants. We cloned the daf-31 gene and it encodes an ortholog of the arrest-defective-1 protein (ARD1) that is the catalytic subunit of the major N alpha-acetyltransferase (NatA). A daf-31 promoter::GFP reporter gene indicates daf-31 is expressed in multiple tissues including neurons, pharynx, intestine and hypodermal cells. Interestingly, overexpression of daf-31 enhances the longevity phenotype of daf-2 mutants, which is dependent on the forkhead transcription factor (FOXO) DAF-16. We demonstrate that overexpression of daf-31 stimulates the transcriptional activity of DAF-16 without influencing its subcellular localization. These data reveal an essential role of NatA in controlling C. elegans life history and also a novel interaction between ARD1 and FOXO transcription factors, which may contribute to understanding the function of ARD1 in mammals.

  6. 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.

  7. Enhancing chemosensitivity to gemcitabine via RNA interference targeting the catalytic subunits of protein kinase CK2 in human pancreatic cancer cells

    International Nuclear Information System (INIS)

    Kreutzer, Jan N; Ruzzene, Maria; Guerra, Barbara

    2010-01-01

    Pancreatic cancer is a complex genetic disorder that is characterized by rapid progression, invasiveness, resistance to treatment and high molecular heterogeneity. Various agents have been used in clinical trials showing only modest improvements with respect to gemcitabine-based chemotherapy, which continues to be the standard first-line treatment for this disease. However, owing to the overwhelming molecular alterations that have been reported in pancreatic cancer, there is increasing focus on targeting molecular pathways and networks, rather than individual genes or gene-products with a combination of novel chemotherapeutic agents. Cells were transfected with small interfering RNAs (siRNAs) targeting the individual CK2 subunits. The CK2 protein expression levels were determined and the effect of its down-regulation on chemosensitization of pancreatic cancer cells was investigated. The present study examined the impact on cell death following depletion of the individual protein kinase CK2 catalytic subunits alone or in combination with gemcitabine and the molecular mechanisms by which this effect is achieved. Depletion of the CK2α or -α' subunits in combination with gemcitabine resulted in marked apoptotic and necrotic cell death in PANC-1 cells. We show that the mechanism of cell death is associated with deregulation of distinct survival signaling pathways. Cellular depletion of CK2α leads to phosphorylation and activation of MKK4/JNK while down-regulation of CK2α' exerts major effects on the PI3K/AKT pathway. Results reported here show that the two catalytic subunits of CK2 contribute differently to enhance gemcitabine-induced cell death, the reduced level of CK2α' being the most effective and that simultaneous reduction in the expression of CK2 and other survival factors might be an effective therapeutic strategy for enhancing the sensitivity of human pancreatic cancer towards chemotherapeutic agents

  8. Heterologous desensitization of adenylate cyclase from pigeon erythrocytes under the action of the catalytic subunit of cAMP-dependent protein kinase

    International Nuclear Information System (INIS)

    Popov, K.M.; Bulargina, T.V.; Severin, E.S.

    1985-01-01

    Preincubation of the plasma membranes from pigeon erythrocytes with the catalytic subunit of cAMP-dependent protein kinase leads to desensitization of adenylate cyclase of the erythrocytes. The adenylate cyclase activity, measured in the presence of 10 μM isoproterenol and 50 μM GTP-γ-S, is decreased by 40% in 10 min of incubation, while the activity in the presence of 50 μM GTP-γ-S is decreased by 35% in 20 min. The decrease in the adenylate cyclase activity is due to an increase in the lag phase of activation of the enzyme in the presence of a GTP analog stable to hydrolysis and a decrease in the activity in the steady-state phase of activation. Heterologous desensitization of adenylate cyclase under the action of cAMP-dependent protein kinase is coupled with a decrease in the number of β-adrenoreceptors capable of passing into a state of high affinity for antagonists in the absence of guanylic nucleotides. The influence of the catalytic subunit on adenylate cyclase entirely models the process of desensitization of the enzyme absorbed in the influence of isoproterenol or cAMP on erythrocytes

  9. Small-angle scattering studies show distinct conformations of calmodulin in its complexes with two peptides based on the regulatory domain of the catalytic subunit of phosphorylase kinase

    International Nuclear Information System (INIS)

    Trewhella, J.; Blumenthal, D.K.; Rokop, S.E.; Seeger, P.A.

    1990-01-01

    Small-angle X-ray and neutron scattering have been used to study the solution structures of calmodulin complexed with synthetic peptides corresponding to residues 342-366 and 301-326, designated PhK5 and PhK13, respectively, in the regulatory domain of the catalytic subunit of skeletal muscle phosphorylase kinase. The scattering data show that binding of PhK5 to calmodulin induces a dramatic contraction of calmodulin, similar to that previously observed when calmodulin is complexed with the calmodulin-binding domain peptide from rabbit skeletal muscle myosin light chain kinase. In contrast, calmodulin remains extended upon binding PhK13. In the presence of both peptides, calmodulin also remains extended. Apparently, the presence of PhK13 inhibits calmodulin from undergoing the PhK5-induced contraction. These data indicate that there is a fundamentally different type of calmodulin-target enzyme interaction in the case of the catalytic subunit of phosphorylase kinase compared with that for myosin light chain kinase

  10. 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) ar......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) 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...... when ATM is present and its kinase activity is intact. The ability of ATM to compensate for DNA-PKcs kinase activity depends on the integrity of three threonines in DNA-PKcs that are phosphorylation targets of ATM, suggesting that ATM can modulate DNA-PKcs activity through direct phosphorylation of DNA...

  11. Hydrogen bonds between the alpha and beta subunits of the F1-ATPase allow communication between the catalytic site and the interface of the beta catch loop and the gamma subunit.

    Science.gov (United States)

    Boltz, Kathryn W; Frasch, Wayne D

    2006-09-19

    F(1)-ATPase mutations in Escherichia coli that changed the strength of hydrogen bonds between the alpha and beta subunits in a location that links the catalytic site to the interface between the beta catch loop and the gamma subunit were examined. Loss of the ability to form the hydrogen bonds involving alphaS337, betaD301, and alphaD335 lowered the k(cat) of ATPase and decreased its susceptibility to Mg(2+)-ADP-AlF(n) inhibition, while mutations that maintain or strengthen these bonds increased the susceptibility to Mg(2+)-ADP-AlF(n) inhibition and lowered the k(cat) of ATPase. These data suggest that hydrogen bonds connecting alphaS337 to betaD301 and betaR323 and connecting alphaD335 to alphaS337 are important to transition state stabilization and catalytic function that may result from the proper alignment of catalytic site residues betaR182 and alphaR376 through the VISIT sequence (alpha344-348). Mutations betaD301E, betaR323K, and alphaR282Q changed the rate-limiting step of the reaction as determined by an isokinetic plot. Hydrophobic mutations of betaR323 decreased the susceptibility to Mg(2+)-ADP-AlF(n)() inhibition and lowered the number of interactions required in the rate-limiting step yet did not affect the k(cat) of ATPase, suggesting that betaR323 is important to transition state formation. The decreased rate of ATP synthase-dependent growth and decreased level of lactate-dependent quenching observed with alphaD335, betaD301, and alphaE283 mutations suggest that these residues may be important to the formation of an alternative set of hydrogen bonds at the interface of the alpha and beta subunits that permits the release of intersubunit bonds upon the binding of ATP, allowing gamma rotation in the escapement mechanism.

  12. Phosphorylation of protein kinase A (PKA) regulatory subunit RIα by protein kinase G (PKG) primes PKA for catalytic activity in cells.

    Science.gov (United States)

    Haushalter, Kristofer J; Casteel, Darren E; Raffeiner, Andrea; Stefan, Eduard; Patel, Hemal H; Taylor, Susan S

    2018-03-23

    cAMP-dependent protein kinase (PKAc) is a pivotal signaling protein in eukaryotic cells. PKAc has two well-characterized regulatory subunit proteins, RI and RII (each having α and β isoforms), which keep the PKAc catalytic subunit in a catalytically inactive state until activation by cAMP. Previous reports showed that the RIα regulatory subunit is phosphorylated by cGMP-dependent protein kinase (PKG) in vitro , whereupon phosphorylated RIα no longer inhibits PKAc at normal (1:1) stoichiometric ratios. However, the significance of this phosphorylation as a mechanism for activating type I PKA holoenzymes has not been fully explored, especially in cellular systems. In this study, we further examined the potential of RIα phosphorylation to regulate physiologically relevant "desensitization" of PKAc activity. First, the serine 101 site of RIα was validated as a target of PKGIα phosphorylation both in vitro and in cells. Analysis of a phosphomimetic substitution in RIα (S101E) showed that modification of this site increases PKAc activity in vitro and in cells, even without cAMP stimulation. Numerous techniques were used to show that although Ser 101 variants of RIα can bind PKAc, the modified linker region of the S101E mutant has a significantly reduced affinity for the PKAc active site. These findings suggest that RIα phosphorylation may be a novel mechanism to circumvent the requirement of cAMP stimulus to activate type I PKA in cells. We have thus proposed a model to explain how PKG phosphorylation of RIα creates a "sensitized intermediate" state that is in effect primed to trigger PKAc activity.

  13. Regulation of human gamma-glutamylcysteine synthetase: co-ordinate induction of the catalytic and regulatory subunits in HepG2 cells.

    Science.gov (United States)

    Galloway, D C; Blake, D G; Shepherd, A G; McLellan, L I

    1997-11-15

    We have shown that in HepG2 cells treatment with 75 microM t-butylhydroquinone (tBHQ) results in a 2.5-fold increase in glutathione concentration, as part of an adaptive response to chemical stress. In these cells the elevation in intracellular glutathione level was found to be accompanied by an increase of between 2-fold and 3-fold in the level of the 73 kDa catalytic subunit of gamma-glutamylcysteine synthetase (heavy subunit, GCSh) and the 31 kDa regulatory subunit (light subunit, GCSl). Levels of GCSh and GCSl mRNA were increased by up to 5-fold in HepG2 cells in response to tBHQ. To study the transcriptional regulation of GCSl, we subcloned 6.7 kb of the upstream region of the human GCSl gene (GLCLR) from a genomic clone isolated from a P1 lymphoblastoid cell line genomic library. HepG2 cells were transfected with GLCLR promoter reporter constructs and treated with tBHQ. This resulted in an induction of between 1.5-fold and 3.5-fold in reporter activity, indicating that transcriptional regulation of GLCLR is likely to contribute to the induction of GCSl by tBHQ in HepG2 cells. Sequence analysis of the promoter region demonstrated the presence of putative enhancer elements including AP-1 sites and an antioxidant-responsive element, which might be involved in the observed induction of the GLCLR promoter.

  14. Crystal structure of a C-terminal deletion mutant of human protein kinase CK2 catalytic subunit

    DEFF Research Database (Denmark)

    Ermakova, Inessa; Boldyreff, Brigitte; Issinger, Olaf-Georg

    2003-01-01

    structure of a C-terminal deletion mutant of human CK2alpha was solved and refined to 2.5A resolution. In the crystal the CK2alpha mutant exists as a monomer in agreement with the organization of the subunits in the CK2 holoenzyme. The refined structure shows the helix alphaC and the activation segment, two...

  15. Novel somatic mutations in the catalytic subunit of the protein kinase A as a cause of adrenal Cushing's syndrome: a European multicentric study.

    Science.gov (United States)

    Di Dalmazi, Guido; Kisker, Caroline; Calebiro, Davide; Mannelli, Massimo; Canu, Letizia; Arnaldi, Giorgio; Quinkler, Marcus; Rayes, Nada; Tabarin, Antoine; Laure Jullié, Marie; Mantero, Franco; Rubin, Beatrice; Waldmann, Jens; Bartsch, Detlef K; Pasquali, Renato; Lohse, Martin; Allolio, Bruno; Fassnacht, Martin; Beuschlein, Felix; Reincke, Martin

    2014-10-01

    Somatic mutations in PRKACA gene, encoding the catalytic subunit of protein kinase A (PKA), have been recently found in a high proportion of sporadic adenomas associated with Cushing's syndrome. The aim was to analyze the PRKACA mutation in a large cohort of patients with adrenocortical masses. Samples from nine European centers were included (Germany, n = 4; Italy, n = 4; France, n = 1). Samples were drawn from 149 patients with nonsecreting adenomas (n = 32 + 2 peritumoral), subclinical hypercortisolism (n = 36), Cushing's syndrome (n = 64 + 2 peritumoral), androgen-producing tumors (n = 4), adrenocortical carcinomas (n = 5 + 2 peritumoral), and primary bilateral macronodular adrenal hyperplasias (n = 8). Blood samples were available from patients with nonsecreting adenomas (n = 15), subclinical hypercortisolism (n = 10), and Cushing's syndrome (n = 35). Clinical and hormonal data were collected. DNA amplification by PCR of exons 6 and 7 of the PRKACA gene and direct sequencing were performed. PRKACA heterozygous mutations were found in 22/64 samples of Cushing's syndrome patients (34%). No mutations were found in peritumoral tissue and blood samples or in other tumors examined. The c.617A>C (p.Leu206Arg) occurred in 18/22 patients. Furthermore, two novel mutations were identified: c.600_601insGTG/p.Cys200_Gly201insVal in three patients and c.639C>G+c.638_640insATTATCCTGAGG/p.Ser213Arg+p.Leu212_Lys214insIle-Ile-Leu-Arg) in one. All the mutations involved a region implicated in interaction between PKA regulatory and catalytic subunits. Patients with somatic PRKACA mutations showed higher levels of cortisol after dexamethasone test and a smaller adenoma size, compared with nonmutated subjects. These data confirm and extend previous observations that somatic PRKACA mutations are specific for adrenocortical adenomas causing Cushing's syndrome.

  16. Functional changes in the properties of the β-adrenoreceptors of pigeon erythrocytes under the action of the catalytic subunit of cAMP-dependent protein kinase

    International Nuclear Information System (INIS)

    Popov, K.M.; Bulargina, T.V.; Severin, E.S.

    1986-01-01

    The β-adrenoreceptors were solubilized from the plasma membranes of pigeon erythrocytes, treated with N-ethylmaleimide, using deoxycholate. The removal of the deoxycholate leads to incorporation of receptors into phospholipid vesicles and a restoration of their biological activity. After fusion of vesicles containing reconstituted receptors with vesicles containing the N/sub s/-protein and the catalytic component, a restoration of the hormonal activity of the enzyme was observed. If vesicles containing β-adrenoreceptors were incubated before fusion with the catalytic subunit of cAMP-dependent protein kinase, the hormonal activity of the preparation obtained was lowered by 45-50%. The decrease in activity occurred on account of an increase in the lag phase of activation of the enzyme in the presence of isoproterenol and GPP(NH)p, as well as on account of a decrease in the activity in the stationary phase of activation. Phosphorylation of the β-adrenoreceptors leads to a decrease in the content of the ternary isoproterenol-receptor-N/sub s/-protein complex, participating in the activation of adenylate cyclase. Thus, phosphorylation of the receptors leads to disruptions of the mechanism of transmission of the hormonal signal, analogous to those observed in the desensitization of adenylate cyclase

  17. Mammalian α-polymerase: cloning of partial complementary DNA and immunobinding of catalytic subunit in crude homogenate protein blots

    International Nuclear Information System (INIS)

    SenGupta, D.N.; Kumar, P.; Zmudzka, B.Z.; Coughlin, S.; Vishwanatha, J.K.; Robey, F.A.; Parrott, C.; Wilson, S.H.

    1987-01-01

    A new polyclonal antibody against the α-polymerase catalytic polypeptide was prepared by using homogeneous HeLa cellα-polymerase. The antibody neutralized α-polymerase activity and was strong and specific for the α-polymerase catalytic polypeptide (M/sub r/ 183,000) in Western blot analysis of crude extracts of HeLa cells. The antibody was used to screen a cDNA library of newborn rat brain poly(A+) RNA in λgt11. A positive phage was identified and plaque purified. This phage, designated λpolα1.2, also was found to be positive with an antibody against Drosophila α-polymerase. The insert in λpolα1.2 (1183 base pairs) contained a poly(A) sequence at the 3' terminus and a short in-phase open reading frame at the 5' terminus. A synthetic oligopeptide (eight amino acids) corresponding to the open reading frame was used to raise antiserum in rabbits. Antibody affinity purified from this serum was found to be immunoreactive against purified α-polymerase by enzyme-linked immunosorbent assay and was capable of immunoprecipitating α-polymerase. This indicated the λpolα1.2 insert encoded an α-polymerase epitope and suggested that the cDNA corresponded to an α-polymerase mRNA. This was confirmed in hybrid selection experiments using pUC9 containing the cDNA insert and poly(A+) RNA from newborn rat brain; the insert hybridized to mRNA capable of encoding α-polymerase catalytic polypeptides. Northern blot analysis of rat brain poly(A+) RNA revealed that this mRNA is ∼5.4 kilobases

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

    International Nuclear Information System (INIS)

    2013-01-01

    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.

  19. Global regulatory roles of the cAMP/PKA pathway revealed by phenotypic, transcriptomic and phosphoproteomic analyses in a null mutant of the PKA catalytic subunit in Candida albicans.

    Science.gov (United States)

    Cao, Chengjun; Wu, Mei; Bing, Jian; Tao, Li; Ding, Xuefen; Liu, Xiaoyun; Huang, Guanghua

    2017-07-01

    The conserved cAMP-dependent protein kinase (PKA) plays critical roles in the regulation of morphological transitions and virulence in the human fungal pathogen Candida albicans. It has long been thought that the PKA catalytic subunit is essential for cell viability in this fungus. Paradoxically, the single adenylyl cyclase-encoding gene, CYR1, which is required for the production of cAMP in C. albicans, is not essential for cell growth. Here, a double mutant of TPK1 and TPK2 (tpk2/tpk2 tpk1/tpk1, t2t1), which encode two isoforms of the PKA catalytic subunit was successfully generated, suggesting that this subunit is not essential for cell viability. Inactivation of the PKA catalytic subunit blocked filamentation and dramatically attenuated white-to-opaque switching, but promoted sexual mating. Comparative transcriptomic analyses demonstrated that the t2t1 and cyr1/cyr1 mutants exhibited similar global gene expression profiles. Compared with the WT strain, the general transcriptional activity and metabolism were significantly decreased in both the t2t1 and cyr1/cyr1 mutants. Using combined phosphoproteomic and bioinformatic analyses, we identified 181 potential PKA phosphorylation targets, which represent 148 unique proteins involved in a wide spectrum of biological processes. The study sheds new insights into the global regulatory features of the cAMP/PKA pathway in C. albicans. © 2017 John Wiley & Sons Ltd.

  20. The heterotrimeric G protein Gβ1 interacts with the catalytic subunit of protein phosphatase 1 and modulates G protein-coupled receptor signaling in platelets.

    Science.gov (United States)

    Pradhan, Subhashree; Khatlani, Tanvir; Nairn, Angus C; Vijayan, K Vinod

    2017-08-11

    Thrombosis is caused by the activation of platelets at the site of ruptured atherosclerotic plaques. This activation involves engagement of G protein-coupled receptors (GPCR) on platelets that promote their aggregation. Although it is known that protein kinases and phosphatases modulate GPCR signaling, how serine/threonine phosphatases integrate with G protein signaling pathways is less understood. Because the subcellular localization and substrate specificity of the catalytic subunit of protein phosphatase 1 (PP1c) is dictated by PP1c-interacting proteins, here we sought to identify new PP1c interactors. GPCRs signal via the canonical heterotrimeric Gα and Gβγ subunits. Using a yeast two-hybrid screen, we discovered an interaction between PP1cα and the heterotrimeric G protein Gβ 1 subunit. Co-immunoprecipitation studies with epitope-tagged PP1c and Gβ 1 revealed that Gβ 1 interacts with the PP1c α, β, and γ1 isoforms. Purified PP1c bound to recombinant Gβ 1 -GST protein, and PP1c co-immunoprecipitated with Gβ 1 in unstimulated platelets. Thrombin stimulation of platelets induced the dissociation of the PP1c-Gβ 1 complex, which correlated with an association of PP1c with phospholipase C β3 (PLCβ3), along with a concomitant dephosphorylation of the inhibitory Ser 1105 residue in PLCβ3. siRNA-mediated depletion of GNB1 (encoding Gβ 1 ) in murine megakaryocytes reduced protease-activated receptor 4, activating peptide-induced soluble fibrinogen binding. Thrombin-induced aggregation was decreased in PP1cα -/- murine platelets and in human platelets treated with a small-molecule inhibitor of Gβγ. Finally, disruption of PP1c-Gβ 1 complexes with myristoylated Gβ 1 peptides containing the PP1c binding site moderately decreased thrombin-induced human platelet aggregation. These findings suggest that Gβ 1 protein enlists PP1c to modulate GPCR signaling in platelets.

  1. Long-term functional impairment of hemopoietic progenitor cells engineered to express the S1 catalytic subunit of pertussis toxin.

    Science.gov (United States)

    Bonig, Halvard; Rohmer, Laurence; Papayannopoulou, Thalia

    2005-06-01

    A large body of data suggests that pertussis toxin (PTX)-sensitive G protein signals in mature and immature hemopoietic cells control their migration patterns in vitro and in vivo. These effects were derived after treatment of cells or animals with PTX. To circumvent several inherent problems of PTX holotoxin treatment, we expressed the S1 catalytic activity of PTX, thus blocking Gi protein signaling, in 32D murine myeloid progenitor cells and in primary human CD34+ cells, and studied its functional consequences. S1 was expressed using viral vectors. Effects of Gi protein blockade on proliferation, migration, adhesion, and gene expression were tested in vitro. S1 expression was nontoxic for the cells; expression and function were stable long-term and not overridden by compensatory mechanisms. S1-transduced 32D cells and primary CD34+ cells migrated poorly and did not contract their cytoskeleton upon treatment with the chemoattractant stromal cell-derived factor -1 (SDF-1), similar to the phenotype induced by PTX treatment. Gene expression studies comparing S1-transduced and control 32D cells uncovered four genes, expression of which was regulated by Gi protein blockade. Of interest, although SDF-1 signaling was inhibited, comparison between SDF-1-treated and untreated cells suggests that SDF-1 stimulation does not depend on de novo gene expression in these cells. Furthermore, when injected into nonobese diabetic/severe combined immunodeficient mice, seeding of S1-expressing 32D cells to bone marrow was largely blocked. Expression of S1 is an effective approach for studying long-term functional consequences of Gi protein blockade in hemopoietic cells in vitro and in vivo.

  2. 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)

    Schrader, Mark; Burger, Angelika M; Müller, Markus; Krause, Hans; Straub, Bernd; Schostak, Martin; Schulze, Wolfgang; Lauke, Heidrun; Miller, Kurt

    2002-01-01

    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

  3. 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

    Directory of Open Access Journals (Sweden)

    Schulze Wolfgang

    2002-11-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusions 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.

  4. T-Cell-Specific Loss of the PI-3-Kinase p110α Catalytic Subunit Results in Enhanced Cytokine Production and Antitumor Response

    Directory of Open Access Journals (Sweden)

    Laura Aragoneses-Fenoll

    2018-02-01

    Full Text Available Class IA phosphatidylinositol 3-kinase (PI3K catalytic subunits p110α and p110δ are targets in cancer therapy expressed at high levels in T lymphocytes. The role of p110δ PI3K in normal or pathological immune responses is well established, yet the importance of p110α subunits in T cell-dependent immune responses is not clear. To address this problem, mice with p110α conditionally deleted in CD4+ and CD8+ T lymphocytes (p110α−/−ΔT were used. p110α−/−ΔT mice show normal development of T cell subsets, but slightly reduced numbers of CD4+ T cells in the spleen. “In vitro,” TCR/CD3 plus CD28 activation of naive CD4+ and CD8+ p110α−/−ΔT T cells showed enhanced effector function, particularly IFN-γ secretion, T-bet induction, and Akt, Erk, or P38 activation. Tfh derived from p110α−/−ΔT cells also have enhanced responses when compared to normal mice, and IL-2 expanded p110α−/−ΔT CD8+ T cells had enhanced levels of LAMP-1 and Granzyme B. By contrast, the expansion of p110α−/−ΔT iTreg cells was diminished. Also, p110α−/−ΔT mice had enhanced anti-keyhole limpet hemocyanin (KLH IFN-γ, or IL-4 responses and IgG1 and IgG2b anti-KLH antibodies, using CFA or Alum as adjuvant, respectively. When compared to WT mice, p110α−/−ΔT mice inoculated with B16.F10 melanoma showed delayed tumor progression. The percentage of CD8+ T lymphocytes was higher and the percentage of Treg cells lower in the spleen of tumor-bearing p110α−/−ΔT mice. Also, IFN-γ production in tumor antigen-activated spleen cells was enhanced. Thus, PI3K p110α plays a significant role in antigen activation and differentiation of CD4+ and CD8+ T lymphocytes modulating antitumor immunity.

  5. Isoform-specific interactions between meprin metalloproteases and the catalytic subunit of protein kinase A: significance in acute and chronic kidney injury

    Science.gov (United States)

    Niyitegeka, Jean-Marie V.; Bastidas, Adam C.; Newman, Robert H.; Taylor, Susan S.

    2014-01-01

    Meprin metalloproteases are abundantly expressed in the brush-border membranes of kidney proximal tubules. Meprins are implicated in ischemia-reperfusion (IR)-induced renal injury and diabetic nephropathy. The protein kinase A (PKA) signaling pathway modulates extracellular matrix metabolism in diabetic kidneys. The present study evaluated isoform-specific interactions between the catalytic subunit of PKA (PKA C) and meprins. To this end, cytosolic-enriched kidney proteins from meprin αβ double knockout mice, and purified forms of recombinant mouse PKA Cα, Cβ1, and Cβ2, were incubated with activated forms of either homomeric meprin A or meprin B. The cleaved protein products were subjected to SDS-PAGE and analyzed by Coomassie staining and Western blot analysis. While meprin A only cleaved PKA Cβ1, meprin B cleaved all three PKA C isoforms. Analysis of the proteolytic fragments by mass spectrometry revealed that meprin A and B cleave the PKA C isoforms at defined sites, resulting in unique cleavage products. Michaelis-Menten enzyme kinetics demonstrated that meprin B-mediated cleavage of PKA Cα occurs at a rate consistent with that of other physiologically relevant meprin substrates. Meprin cleavage decreased the kinase activity of PKA Cα, Cβ1, and Cβ2. PKA C levels were higher in diabetic kidneys, with evidence of in vivo fragmentation in wild-type diabetic kidneys. Confocal microscopy showed localization of meprin A in the glomeruli of diabetic kidneys. At 3 h post-IR, PKA C levels in proximal tubules decreased compared with distal tubules, which lack meprins. These data suggest that meprins may impact kidney injury, in part, via modulation of PKA signaling pathways. PMID:25354939

  6. DNA-dependent protein kinase catalytic subunit functions in metastasis and influences survival in advanced-stage laryngeal squamous cell carcinoma.

    Science.gov (United States)

    He, Sha-Sha; Chen, Yong; Shen, Xiao-Ming; Wang, Hong-Zhi; Sun, Peng; Dong, Jun; Guo, Gui-Fang; Chen, Ju-Gao; Xia, Liang-Ping; Hu, Pei-Li; Qiu, Hui-Juan; Liu, Shou-Sheng; Zhou, Yi-Xin; Wang, Wei; Hu, Wei-Han; Cai, Xiu-Yu

    2017-01-01

    Background: DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is known to function in several types of cancer. In this study, we investigated the expression and clinicopathologic significance of DNA-PKcs in laryngeal squamous cell carcinoma (LSCC). Methods: We conducted a retrospective study of 208 patients with advanced-stage LSCC treated at Sun Yat-sen University Cancer Center, Guangzhou, China. We assessed DNA-PKcs and p16INK4a (p16) status using immunohistochemistry. We examined the association between DNA-PKcs expression and clinicopathologic features and survival outcomes. To evaluate the independent prognostic relevance of DNA-PKcs, we used univariate and multivariate Cox regression models. We estimated overall survival (OS) and distant metastasis-free survival (DMFS) using the Kaplan-Meier method. Results: Immunohistochemical analyses revealed that 163/208 (78.4%) of the LSCC tissue samples exhibited high DNA-PKcs expression. High DNA-PKcs expression was significantly associated with survival outcomes ( P = 0.016) and distant metastasis ( P = 0.02; chi-squared test). High DNA-PKcs expression was associated with a significantly shorter OS and DMFS than low DNA-PKcs expression ( P = 0.029 and 0.033, respectively; log-rank test), and was associated with poor OS in the p16-positive subgroup ( P = 0.047). Multivariate analysis identified DNA-PKcs as an independent prognostic indicator of OS and DMFS in all patients ( P = 0.039 and 0.037, respectively). Conclusions : Our results suggest that patients with LSCC in whom DNA-PKcs expression is elevated have a higher incidence of distant metastasis and a poorer prognosis. DNA-PKcs may represent a marker of tumor progression in patients with p16-positive LSCC.

  7. 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

    2014-06-25

    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.

  8. DNA requirements for interaction of the C-terminal region of Ku80 with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs).

    Science.gov (United States)

    Radhakrishnan, Sarvan Kumar; Lees-Miller, Susan P

    2017-09-01

    Non-homologous end joining (NHEJ) is the major pathway for the repair of ionizing radiation induced DNA double strand breaks (DSBs) in human cells. Critical to NHEJ is the DNA-dependent interaction of the Ku70/80 heterodimer with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to form the DNA-PK holoenzyme. However, precisely how Ku recruits DNA-PKcs to DSBs ends to enhance its kinase activity has remained enigmatic, with contradictory findings reported in the literature. Here we address the role of the Ku80 C-terminal region (CTR) in the DNA-dependent interaction of Ku70/80 with DNA-PKcs using purified components and defined DNA structures. Our results show that the Ku80 CTR is required for interaction with DNA-PKcs on short segments of blunt ended 25bp dsDNA or 25bp dsDNA with a 15-base poly dA single stranded (ss) DNA extension, but this requirement is less stringent on longer dsDNA molecules (35bp blunt ended dsDNA) or 25bp duplex DNA with either a 15-base poly dT or poly dC ssDNA extension. Moreover, the DNA-PKcs-Ku complex preferentially forms on 25 bp DNA with a poly-pyrimidine ssDNA extension.Our work clarifies the role of the Ku80 CTR and dsDNA ends on the interaction of DNA-PKcs with Ku and provides key information to guide assembly and biology of NHEJ complexes. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. 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.

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

    International Nuclear Information System (INIS)

    Boylan, Joan M.; Salomon, Arthur R.; Tantravahi, Umadevi; Gruppuso, Philip A.

    2015-01-01

    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

  11. Crystal structure of a polyhistidine-tagged recombinant catalytic subunit of cAMP-dependent protein kinase complexed with the peptide inhibitor PKI(5-24) and adenosine.

    Science.gov (United States)

    Narayana, N; Cox, S; Shaltiel, S; Taylor, S S; Xuong, N

    1997-04-15

    The crystal structure of the hexahistidine-tagged mouse recombinant catalytic subunit (H6-rC) of cAMP-dependent protein kinase (cAPK), complexed with a 20-residue peptide inhibitor from the heat-stable protein kinase inhibitor PKI(5-24) and adenosine, was determined at 2.2 A resolution. Novel crystallization conditions were required to grow the ternary complex crystals. The structure was refined to a final crystallographic R-factor of 18.2% with good stereochemical parameters. The "active" enzyme adopts a "closed" conformation as found in rC:PKI(5-24) [Knighton et al. (1991a,b) Science 253, 407-414, 414-420] and packs in a similar manner with the peptide providing a major contact surface. This structure clearly defines the subsites of the unique nucleotide binding site found in the protein kinase family. The adenosine occupies a mostly hydrophobic pocket at the base of the cleft between the two lobes and is completely buried. The missing triphosphate moiety of ATP is filled with a water molecule (Wtr 415) which replaces the gamma-phosphate of ATP. The glycine-rich loop between beta1 and beta2 helps to anchor the phosphates while the ribose ring is buried beneath beta-strand 2. Another ordered water molecule (Wtr 375) is pentacoordinated with polar atoms from adenosine, Leu 49 in beta-strand 1, Glu 127 in the linker strand between the two lobes, Tyr 330, and a third water molecule, Wtr 359. The conserved nucleotide fold can be defined as a lid comprised of beta-strand 1, the glycine-rich loop, and beta-strand 2. The adenine ring is buried beneath beta-strand 1 and the linker strand (120-127) that joins the small and large lobes. The C-terminal tail containing Tyr 330, a segment that lies outside the conserved core, covers this fold and anchors it in a closed conformation. The main-chain atoms of the flexible glycine-rich loop (residues 50-55) in the ATP binding domain have a mean B-factor of 41.4 A2. This loop is quite mobile, in striking contrast to the other

  12. Complex regulation of Hsf1-Skn7 activities by the catalytic subunits of PKA in Saccharomyces cerevisiae: experimental and computational evidences.

    Science.gov (United States)

    Pérez-Landero, Sergio; Sandoval-Motta, Santiago; Martínez-Anaya, Claudia; Yang, Runying; Folch-Mallol, Jorge Luis; Martínez, Luz María; Ventura, Larissa; Guillén-Navarro, Karina; Aldana-González, Maximino; Nieto-Sotelo, Jorge

    2015-07-27

    The cAMP-dependent protein kinase regulatory network (PKA-RN) regulates metabolism, memory, learning, development, and response to stress. Previous models of this network considered the catalytic subunits (CS) as a single entity, overlooking their functional individualities. Furthermore, PKA-RN dynamics are often measured through cAMP levels in nutrient-depleted cells shortly after being fed with glucose, dismissing downstream physiological processes. Here we show that temperature stress, along with deletion of PKA-RN genes, significantly affected HSE-dependent gene expression and the dynamics of the PKA-RN in cells growing in exponential phase. Our genetic analysis revealed complex regulatory interactions between the CS that influenced the inhibition of Hsf1/Skn7 transcription factors. Accordingly, we found new roles in growth control and stress response for Hsf1/Skn7 when PKA activity was low (cdc25Δ cells). Experimental results were used to propose an interaction scheme for the PKA-RN and to build an extension of a classic synchronous discrete modeling framework. Our computational model reproduced the experimental data and predicted complex interactions between the CS and the existence of a repressor of Hsf1/Skn7 that is activated by the CS. Additional genetic analysis identified Ssa1 and Ssa2 chaperones as such repressors. Further modeling of the new data foresaw a third repressor of Hsf1/Skn7, active only in the absence of Tpk2. By averaging the network state over all its attractors, a good quantitative agreement between computational and experimental results was obtained, as the averages reflected more accurately the population measurements. The assumption of PKA being one molecular entity has hindered the study of a wide range of behaviors. Additionally, the dynamics of HSE-dependent gene expression cannot be simulated accurately by considering the activity of single PKA-RN components (i.e., cAMP, individual CS, Bcy1, etc.). We show that the differential

  13. Basic residues in the 74-83 and 191-198 segments of protein kinase CK2 catalytic subunit are implicated in negative but not in positive regulation by the beta-subunit

    DEFF Research Database (Denmark)

    Sarno, S; Vaglio, P; Marin, O

    1997-01-01

    by the beta-subunit many fold more than that of alpha wild type, while extrastimulation by beta mutant D55L56E57A, observable with alpha wild type, is abolished with these mutants. These data support the conclusion that down regulation by the acidic residues clustered in the N-terminal moiety of beta...... is mediated by basic residues in the 74-83 and in the 191-198 sequences of the alpha-subunit. These are also implicated in substrate recognition consistent with the concept that the N-terminal acidic region of the beta subunit operates as a pseudosubstrate. In contrast, another CK2alpha mutant, V66A, is more...

  14. HupW Protease Specifically Required for Processing of the Catalytic Subunit of the Uptake Hydrogenase in the Cyanobacterium Nostoc sp. Strain PCC 7120

    Science.gov (United States)

    Lindberg, Pia; Devine, Ellenor; Stensjö, Karin

    2012-01-01

    The maturation process of [NiFe] hydrogenases includes a proteolytic cleavage of the large subunit. We constructed a mutant of Nostoc strain PCC 7120 in which hupW, encoding a putative hydrogenase-specific protease, is inactivated. Our results indicate that the protein product of hupW selectively cleaves the uptake hydrogenase in this cyanobacterium. PMID:22020512

  15. Cysteine residues 244 and 458–459 within the catalytic subunit of Na,K-ATPase control the enzyme's hydrolytic and signaling function under hypoxic conditions

    Directory of Open Access Journals (Sweden)

    Irina Yu. Petrushanko

    2017-10-01

    Full Text Available Our previous findings suggested that reversible thiol modifications of cysteine residues within the actuator (AD and nucleotide binding domain (NBD of the Na,K-ATPase may represent a powerful regulatory mechanism conveying redox- and oxygen-sensitivity of this multifunctional enzyme. S-glutathionylation of Cys244 in the AD and Cys 454-458-459 in the NBD inhibited the enzyme and protected cysteines’ thiol groups from irreversible oxidation under hypoxic conditions. In this study mutagenesis approach was used to assess the role these cysteines play in regulation of the Na,K-ATPase hydrolytic and signaling functions. Several constructs of mouse α1 subunit of the Na,K-ATPase were produced in which Cys244, Cys 454-458-459 or Cys 244-454-458-459 were replaced by alanine. These constructs were expressed in human HEK293 cells. Non-transfected cells and those expressing murine α1 subunit were exposed to hypoxia or treated with oxidized glutathione (GSSG. Both conditions induced inhibition of the wild type Na,K-ATPase. Enzymes containing mutated mouse α1 lacking Cys244 or all four cysteines (Cys 244-454-458-459 were insensitive to hypoxia. Inhibitory effect of GSSG was observed for wild type murine Na,K-ATPase, but was less pronounced in Cys454-458-459Ala mutant and completely absent in the Cys244Ala and Cys 244-454-458-459Ala mutants. In cells, expressing wild type enzyme, ouabain induced activation of Src and Erk kinases under normoxic conditions, whereas under hypoxic conditions this effect was inversed. Cys454-458-459Ala substitution abolished Src kinase activation in response to ouabain treatment, uncoupled Src from Erk signaling, and interfered with O2-sensitivity of Na,K-ATPase signaling function. Moreover, modeling predicted that S-glutathionylation of Cys 458 and 459 should prevent inhibitory binding of Src to NBD. Our data indicate for the first time that cysteine residues within the AD and NBD influence hydrolytic as well as receptor

  16. Agressividade, estilo de vida criminal e adaptação à prisão

    Directory of Open Access Journals (Sweden)

    Leonel Cunha Gonçalves

    2012-01-01

    Full Text Available O estudo da adaptação à prisão e a classificação dos reclusos pode ajudar a prevenir situações de risco e promover um tratamento penitenciário mais efetivo. Este estudo correlacional explora a relação entre a agressividade, o estilo de vida criminal e a adaptação à prisão, incluindo variáveis sociodemográficas e jurídico-penais. A agressividade é medida pelo Aggression Questionnaire e o estilo de vida criminal pelo Lifestyle Criminality Screening Form. A adaptação à prisão inclui dois indicadores: processos disciplinares e acessos aos serviços clínicos. A amostra é constituída por trinta e um participantes do sexo masculino e nacionalidade portuguesa, detidos num Estabelecimento Prisional Regional. O período de observação teve a duração de cinco meses. Os resultados indicam que a agressividade, a história de consumo de drogas e as penas de menor duração predizem pior adaptação à prisão. Conclui-se que o Aggression Questionnaire se associa aos processos disciplinares e aos acessos aos serviços clínicos.

  17. Rapport financier trimestriel pour le trimestre qui a pris fin le 30 juin ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sophie Comeau

    30 juin 2017 ... Régi par la Loi sur le Centre de recherches pour le développement international ... des retombées; forme des leaders dans les secteurs de l'administration .... Au cours de la période de trois mois qui a pris fin le 30 juin 2017, ...

  18. pour le trimestre qui a pris fin le 30 juin 2013

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    30 juin 2013 ... Conseil des gouverneurs du CRDI. Le mandat des gouverneurs suivants a pris fin le 27 mai 2013 : Margaret Biggs, d'Ottawa, en Ontario;. Faith Mitchell, de Washington, aux États-Unis; Elizabeth Parr-Johnston, de Chester Basin, en Nouvelle-Écosse; Gordon Shirley, de Kingston, en Jamaïque; l'honorable ...

  19. Increased expression of the PI3K catalytic subunit p110δ underlies elevated S6 phosphorylation and protein synthesis in an individual with autism from a multiplex family.

    Science.gov (United States)

    Poopal, Ashwini C; Schroeder, Lindsay M; Horn, Paul S; Bassell, Gary J; Gross, Christina

    2016-01-01

    Dysfunctions in the PI3K/mTOR pathway have gained a lot of attention in autism research. This was initially based on the discovery of several monogenic autism spectrum disorders with mutations or defects in PI3K/mTOR signaling components. Recent genetic studies corroborate that defective PI3K/mTOR signaling might be a shared pathomechanism in autism disorders of so far unknown etiology, but functional molecular analyses in human cells are rare. The goals of this study were to perform a functional screen of cell lines from patients with idiopathic autism for defects in PI3K/mTOR signaling, to test if further functional analyses are suitable to detect underlying molecular mechanisms, and to evaluate this approach as a biomarker tool to identify therapeutic targets. We performed phospho-S6- and S6-specific ELISA experiments on 21 lymphoblastoid cell lines from the AGRE collection and on 37 lymphoblastoid cell lines from the Simons Simplex Collection and their healthy siblings. Cell lines from one individual with increased S6 phosphorylation and his multiplex family were analyzed in further detail to identify upstream defects in PI3K signaling associated with autism diagnosis. We detected significantly increased S6 phosphorylation in 3 of the 21 lymphoblastoid cell lines from AGRE compared to a healthy control and in 1 of the 37 lymphoblastoid cell lines from the Simons Simplex Collection compared to the healthy sibling. Further analysis of cells from one individual with elevated S6 phosphorylation showed increased expression of the PI3K catalytic subunit p110δ, which was also observed in lymphoblastoid cells from other autistic siblings but not unaffected members in his multiplex family. The p110δ-selective inhibitor IC87114 reduced elevated S6 phosphorylation and protein synthesis in this cell line. Our results suggest that functional analysis of PI3K/mTOR signaling is a biomarker tool to identify disease-associated molecular defects that could serve as therapeutic

  20. Nuclear power plant design characteristics. Structure of nuclear power plant design characteristics in the IAEA Power Reactor Information System (PRIS)

    International Nuclear Information System (INIS)

    2007-03-01

    One of the IAEA's priorities has been to maintain the Power Reactor Information System (PRIS) database as a viable and useful source of information on nuclear reactors worldwide. To satisfy the needs of PRIS users as much as possible, the PRIS database has included also a set of nuclear power plant (NPP) design characteristics. Accordingly, the PRIS Technical Meeting, organized in Vienna 4-7 October 2004, initiated a thorough revision of the design data area of the PRIS database to establish the actual status of the data and make improvements. The revision first concentrated on a detailed review of the design data completion and the composition of the design characteristics. Based on the results of the review, a modified set and structure of the unit design characteristics for the PRIS database has been developed. The main objective of the development has been to cover all significant plant systems adequately and provide an even more comprehensive overview of NPP unit designs stored in the PRIS database

  1. Unexpected Binding Mode of a Potent Indeno[1,2-b]indole-Type Inhibitor of Protein Kinase CK2 Revealed by Complex Structures with the Catalytic Subunit CK2α and Its Paralog CK2α′

    Directory of Open Access Journals (Sweden)

    Jennifer Hochscherf

    2017-12-01

    Full Text Available Protein kinase CK2, a member of the eukaryotic protein kinase superfamily, is associated with cancer and other human pathologies and thus an attractive drug target. The indeno[1,2-b]indole scaffold is a novel lead structure to develop ATP-competitive CK2 inhibitors. Some indeno[1,2-b]indole-based CK2 inhibitors additionally obstruct ABCG2, an ABC half transporter overexpressed in breast cancer and co-responsible for drug efflux and resistance. Comprehensive derivatization studies revealed substitutions of the indeno[1,2-b]indole framework that boost either the CK2 or the ABCG2 selectivity or even support the dual inhibition potential. The best indeno[1,2-b]indole-based CK2 inhibitor described yet (IC50 = 25 nM is 5-isopropyl-4-(3-methylbut-2-enyl-oxy-5,6,7,8-tetrahydroindeno[1,2-b]indole-9,10-dione (4p. Herein, we demonstrate the membrane permeability of 4p and describe co-crystal structures of 4p with CK2α and CK2α′, the paralogs of human CK2 catalytic subunit. As expected, 4p occupies the narrow, hydrophobic ATP site of CK2α/CK2α′, but surprisingly with a unique orientation: its hydrophobic substituents point towards the solvent while its two oxo groups are hydrogen-bonded to a hidden water molecule. An equivalent water molecule was found in many CK2α structures, but never as a critical mediator of ligand binding. This unexpected binding mode is independent of the interdomain hinge/helix αD region conformation and of the salt content in the crystallization medium.

  2. Highly conserved small subunit residues influence rubisco large subunit catalysis.

    Science.gov (United States)

    Genkov, Todor; Spreitzer, Robert J

    2009-10-30

    The chloroplast enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the rate-limiting step of photosynthetic CO(2) fixation. With a deeper understanding of its structure-function relationships and competitive inhibition by O(2), it may be possible to engineer an increase in agricultural productivity and renewable energy. The chloroplast-encoded large subunits form the active site, but the nuclear-encoded small subunits can also influence catalytic efficiency and CO(2)/O(2) specificity. To further define the role of the small subunit in Rubisco function, the 10 most conserved residues in all small subunits were substituted with alanine by transformation of a Chlamydomonas reinhardtii mutant that lacks the small subunit gene family. All the mutant strains were able to grow photosynthetically, indicating that none of the residues is essential for function. Three of the substitutions have little or no effect (S16A, P19A, and E92A), one primarily affects holoenzyme stability (L18A), and the remainder affect catalysis with or without some level of associated structural instability (Y32A, E43A, W73A, L78A, P79A, and F81A). Y32A and E43A cause decreases in CO(2)/O(2) specificity. Based on the x-ray crystal structure of Chlamydomonas Rubisco, all but one (Glu-92) of the conserved residues are in contact with large subunits and cluster near the amino- or carboxyl-terminal ends of large subunit alpha-helix 8, which is a structural element of the alpha/beta-barrel active site. Small subunit residues Glu-43 and Trp-73 identify a possible structural connection between active site alpha-helix 8 and the highly variable small subunit loop between beta-strands A and B, which can also influence Rubisco CO(2)/O(2) specificity.

  3. pour le trimestre qui a pris fin le 30 septembre 2014

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    30 sept. 2014 ... d'information financière (normes IFRS). Toutes les ... 42,9 %. (1 684) d'un exercice à l'autre. Écart en %. Budget. 2014-2015. Période de six mois qui a pris fin le 30 septembre. Réalisations. Réalisations. 2013 ... a augmenté de 9,6 millions de dollars (soit 17,5 %) par rapport à ce qu'elle était à la période.

  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. Transcriptional regulators of Na, K-ATPase subunits

    OpenAIRE

    Zhiqin eLi; Sigrid A Langhans

    2015-01-01

    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 developme...

  6. O encontro da militância com a vadiagem nas prisões da Ilha Grande

    Directory of Open Access Journals (Sweden)

    Myrian Sepulveda Santos

    Full Text Available RESUMO A partir do estudo sobre prisões da Ilha Grande na primeira metade do século XX, este artigo investiga a construção de uma cultura punitiva que criminalizou grupos sociais que se encontravam em condições precárias de sobrevivência. O termo “vagabundo”, responsável pela prisão e maus tratos de milhares de indivíduos no período pós-abolicionista, esteve presente em leis e códigos penais, no pensamento de legisladores e em textos ditos científicos. O encontro entre lideranças políticas, adversárias do governo Vargas, e a dita vadiagem nas prisões da Ilha Grande evidenciou tratamentos diferenciados e a naturalização do conceito. Entrevistas com guardas penitenciários da Colônia Agrícola do Distrito Federal, construída em 1942, permitem indicar como essas classificações foram operacionais no interior do sistema prisional e como elas se desdobraram.

  7. Castigo, gestão do risco e da miséria: Novos discursos da prisão na contemporaneidade

    Directory of Open Access Journals (Sweden)

    Rafael de Albuquerque Figueiró

    Full Text Available Resumo Com a falência do discurso ressocializador que marcou a modernidade, a contemporaneidade traz à tona outros discursos em torno do encarceramento, produzindo mudanças nos sistemas jurídico-penais. Nesse sentido, e partindo do referencial teórico-metodológico da análise institucional, o presente artigo realiza uma análise das funções ocupadas pela prisão na contemporaneidade com relação ao público alvo desses equipamentos. Assim, a partir de nossa inserção em uma unidade prisional do sistema prisional do Rio Grande do Norte, realizamos uma observação participante da rotina de trabalho dos agentes penitenciários. Como resultados, apresentamos três analisadores para pensar a prisão: os híbridos prisão-abrigo, prisão-albergue e prisão-masmorra. Tais analisadores revelam que a prisão na contemporaneidade adquire um caráter de equipamento híbrido, ao articular as funções de punição, detenção provisória e gestão da miséria, colocando em xeque qualquer intenção reabilitadora.

  8. Terapia comunitária integrativa: campo de conscientização em uma prisão feminina

    Directory of Open Access Journals (Sweden)

    Rosalice Lopes

    2016-12-01

    Full Text Available Este artigo aborda utilização da Terapia Comunitária Integrativa - TCI numa prisão feminina na cidade de São Paulo. As Rodas de TCI aconteceram de dezembro/2012 a novembro/2013. Serão abordados aspectos gerais sobre criminalidade, características históricas das prisões femininas e a situação atual em São Paulo. Foram realizadas 32 de TCI totalizando 279 pessoas, sendo 258 adultos, 14 adolescentes e 04 crianças. Destes 278 eram mulheres e apenas 1 homem. Participaram presas, algumas gestantes, funcionários e estagiários de Psicologia e Serviço Social. O número de participantes nas Rodas foi variável e a maioria aconteceu com mulheres presas. O presente artigo aborda exclusivamente as experiências com as presas. Os procedimentos adotados seguiram o estabelecido durante a formação; em 31 das Rodas os participantes escolheram o tema, em uma delas seguiu-se o modelo de Roda Temática. É certo de que nesta experiência conseguimos constituir uma diferença favorável na relação com as mulheres presas.

  9. Mulheres imigrantes cabo-verdianas nas prisões portuguesas (des) integração, reclusão e projectos de vida

    OpenAIRE

    Martins, Paula Maria de Pinho da Silva

    2015-01-01

    Dissertação de Mestrado em Relações Interculturais apresentada à Universidade Aberta O presente estudo baseia-se em mulheres imigrantes cabo-verdianas nas prisões portuguesas. A informação foi recolhida no Estabelecimento Prisional de Tires e assentou em mulheres condenadas que cumprem pena efetiva de prisão. Quisemos perceber quais os motivos que levaram estas mulheres imigrantes a abandonarem o seu país de origem, se tiveram dificuldades de integração no país que as acolheu e se em resul...

  10. Association of genetic variants in the promoter region of genes encoding p22phox (CYBA and glutamate cysteine ligase catalytic subunit (GCLC and renal disease in patients with type 1 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Pavin Elizabeth J

    2011-09-01

    Full Text Available Abstract Background Oxidative stress is recognized as a major pathogenic factor of cellular damage caused by hyperglycemia. NOX/NADPH oxidases generate reactive oxygen species and NOX1, NOX2 and NOX4 isoforms are expressed in kidney and require association with subunit p22phox (encoded by the CYBA gene. Increased expression of p22phox was described in animal models of diabetic nephropathy. In the opposite direction, glutathione is one of the main endogenous antioxidants whose plasmatic concentrations were reported to be reduced in diabetes patients. The aim of the present investigation was to test whether functional single nucleotide polymorphisms (SNPs in genes involved in the generation of NADPH-dependent O2•- (-675 T → A in CYBA, unregistered and in glutathione metabolism (-129 C → T in GCLC [rs17883901] and -65 T → C in GPX3 [rs8177412] confer susceptibility to renal disease in type 1 diabetes patients. Methods 401 patients were sorted into two groups according to the presence (n = 104 or absence (n = 196 of overt diabetic nephropathy or according to glomerular filtration rate (GFR estimated by Modification of Diet in Renal Disease (MDRD equation: ≥ 60 mL (n = 265 or 2 (n = 136 and were genotyped. Results No differences were found in the frequency of genotypes between diabetic and non-diabetic subjects. The frequency of GFR CYBA genotypes T/A+A/A (18.7% than in the group carrying the T/T genotype (35.3% (P = 0.0143 and the frequency of GFR GCLC genotypes C/T+T/T (47.1% than in the group carrying the C/C genotype (31.1% (p = 0.0082. Logistic regression analysis identified the presence of at least one A allele of the CYBA SNP as an independent protection factor against decreased GFR (OR = 0.38, CI95% 0.14-0.88, p = 0.0354 and the presence of at least one T allele of the GCLC rs17883901 SNP as an independent risk factor for decreased GFR (OR = 2.40, CI95% 1.27-4.56, p = 0.0068. Conclusions The functional SNPs CYBA -675 T → A and

  11. Catalytic treatment

    Energy Technology Data Exchange (ETDEWEB)

    Bindley, W T.R.

    1931-04-18

    An apparatus is described for the catalytic treatment of liquids, semi-liquids, and gases comprising a vessel into which the liquid, semi-liquid, or gas to be treated is introduced through a common inlet to a chamber within the vessel whence it passes to contact with a catalyst through radially arranged channels or passages to a common outlet chamber.

  12. Compensatory expression of human -Acetylglucosaminyl-1-phosphotransferase subunits in mucolipidosis type III gamma

    OpenAIRE

    Pohl , Sandra; Tiede , Stephan; Castrichini , Monica; Cantz , Michael; Gieselmann , Volkmar; Braulke , Thomas

    2009-01-01

    Abstract The N-Acetylglucosaminyl-1-phosphotransferase plays a key role in the generation of mannose 6-phosphate (M6P) recognition markers essential for efficient transport of lysosomal hydrolases to lysosomes. The phosphotransferase is composed of six subunits (?2, ?2, ?2). The ?- and ?-subunits are catalytically active and encoded by a single gene, GNPTAB, whereas the ?-subunit encoded by GNPTG is proposed to recognize conformational structures common to lysosomal enzymes. Defects in GN...

  13. A impossível governança da saúde em prisão? Reflexões a partir da MACA (Costa do Marfim

    Directory of Open Access Journals (Sweden)

    Frédéric Le Marcis

    2016-07-01

    Full Text Available Resumo Quem governa a saúde nas prisões? Propomos responder a esta questão a partir de um inquérito etnográfico de longaduração realizado na MACA, a Maison d´Arrêtet de Correction d´Abidjan (Costa do Marfim. A análise da governança da saúde, na prática, não pode ser feita sem uma contextualização histórica da prisão na sociedade da Costa do Marfim, nem de uma análise da legitimidade atual da prisão e dos presos como objetos de políticas específicas nesse país. É à luz desse duplo contexto que deve ser analisada a dupla governança da prisão que rege a vida na MACA e sustenta os valores atribuídos à saúde nesse espaço. Um estudo de caso sobre a substituição de um detento que exercia a função de chefe do prédio da enfermaria (chef de bâtiment de l’infirmerie permitirá ilustrar como o reconhecimento desta forma de vida singular é uma condição necessária para uma intervenção eficaz no campo da saúde na prisão.

  14. The structure of the protein phosphatase 2A PR65/A subunit reveals the conformation of its 15 tandemly repeated HEAT motifs

    NARCIS (Netherlands)

    Groves, M R; Hanlon, N; Turowski, P; Hemmings, B A; Barford, D

    1999-01-01

    The PR65/A subunit of protein phosphatase 2A serves as a scaffolding molecule to coordinate the assembly of the catalytic subunit and a variable regulatory B subunit, generating functionally diverse heterotrimers. Mutations of the beta isoform of PR65 are associated with lung and colon tumors. The

  15. Subunits of the Snf1 kinase heterotrimer show interdependence for association and activity.

    Science.gov (United States)

    Elbing, Karin; Rubenstein, Eric M; McCartney, Rhonda R; Schmidt, Martin C

    2006-09-08

    The Snf1 kinase and its mammalian orthologue, the AMP-activated protein kinase (AMPK), function as heterotrimers composed of a catalytic alpha-subunit and two non-catalytic subunits, beta and gamma. The beta-subunit is thought to hold the complex together and control subcellular localization whereas the gamma-subunit plays a regulatory role by binding to and blocking the function of an auto-inhibitory domain (AID) present in the alpha-subunit. In addition, catalytic activity requires phosphorylation by a distinct upstream kinase. In yeast, any one of three Snf1-activating kinases, Sak1, Tos3, or Elm1, can fulfill this role. We have previously shown that Sak1 is the only Snf1-activating kinase that forms a stable complex with Snf1. Here we show that the formation of the Sak1.Snf1 complex requires the beta- and gamma-subunits in vivo. However, formation of the Sak1.Snf1 complex is not necessary for glucose-regulated phosphorylation of the Snf1 activation loop. Snf1 kinase purified from cells lacking the beta-subunits do not contain any gamma-subunit, indicating that the Snf1 kinase does not form a stable alphagamma dimer in vivo. In vitro kinase assays using purified full-length and truncated Snf1 proteins demonstrate that the kinase domain, which lacks the AID, is significantly more active than the full-length Snf1 protein. Addition of purified beta- and gamma-subunits could stimulate the kinase activity of the full-length alpha-subunit but only when all three subunits were present, suggesting an interdependence of all three subunits for assembly of a functional complex.

  16. Superlotação das prisões brasileiras: Operador político da racionalidade contemporânea

    Directory of Open Access Journals (Sweden)

    Flavio Medeiros Rangel

    Full Text Available Resumo O presente artigo teve por objetivo analisar a racionalidade política que rege o sistema prisional brasileiro na atualidade. Para isso, tomou-se como objeto de pesquisa os relatórios de inspeções realizadas em estabelecimentos penais brasileiros pelo Conselho Nacional de Política Criminal e Penitenciária (CNPCP nos anos de 2011 e 2012. A análise da superlotação da população encarcerada possibilitou inferir a lógica não somente limitada às prisões, mas expandida por todo o corpo social, direcionada principalmente àqueles à margem da produção e do consumo e, por isso, a prisão tal como se observou, funciona como efeito que conserva a função de reprodução desta racionalidade.

  17. 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

    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, ...

  18. 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.

  19. Crystal Structure of the Oxazolidinone Antibiotic Linezolid Bound to the 50S Ribosomal Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Ippolito,J.; Kanyo, Z.; Wang, D.; Franceschi, F.; Moore, P.; Steitz, T.; Duffy, E.

    2008-01-01

    The oxazolidinone antibacterials target the 50S subunit of prokaryotic ribosomes. To gain insight into their mechanism of action, the crystal structure of the canonical oxazolidinone, linezolid, has been determined bound to the Haloarcula marismortui 50S subunit. Linezolid binds the 50S A-site, near the catalytic center, which suggests that inhibition involves competition with incoming A-site substrates. These results provide a structural basis for the discovery of improved oxazolidinones active against emerging drug-resistant clinical strains.

  20. A garantia da ordem pública como fundamento para a prisão preventiva e o desenvolvimento de seu conceito no Supremo Tribunal Federal

    OpenAIRE

    Soares, Antonio Marcos

    2013-01-01

    Resumo: Esta monografia tem como objetivo tratar de forma pormenorizada a garantia da ordem pública, circunstância legal autorizadora da decretação da prisão preventiva do imputado trazida pelo artigo 312, do Código de Processo Penal. Trata-se de instituto dotado de um conceito vago que enseja custódia provisória, a qual deveria apresentar natureza cautelar, porém, assume contornos diversos da instrumentalidade lhe exigida. No mais das vezes é adotada como medida de defesa social, assumindo a...

  1. Probing the functional subunits of the tonoplast H+-ATPase

    International Nuclear Information System (INIS)

    Randall, S.K.; Lai, S.; Sze, H.

    1986-01-01

    The tonoplast ATPase of oat roots is composed of at least three polypeptides of 72, 60, and 16 kDa. The 16 kDA polypeptide covalently binds N,N'-dicyclohexylcarbodiimide and is postulated to be a component of the proton channel. Initial studies to identify other subunits indicate that both the 72 and 60 kDa subunits covalently bind 14 C]-7-chloro-4-nitrobenzo-2-oxa-1,3-diazole and [ 14 C]N-ethylamleimide, inhibitors of the tonoplast ATPase. ATP prevents binding of these inhibitors suggesting that both the 72 and 60 kDa subunits are involved in substrate binding. Polyclonal antibody has been made to the 72 kDa subunit. Western blot analysis of tonoplast vesicles reveals single reactive polypeptide (72 kDa). The antibody shows no cross-reactivity towards either the mitochondrial F 1 -ATPase or the plasma membrane ATPase. This antibody specifically inhibits ATP hydrolysis and ATP-dependent H + pumping in native tonoplast vesicles. The authors conclude that the 72 kDa subunit is intimately associated with the catalytic (or ATP-binding) site

  2. VALE QUANTO PESA: o que leva(m mulheres grávidas à prisão?

    Directory of Open Access Journals (Sweden)

    Heloisa Vieira Simões

    2017-11-01

    Full Text Available O exponencial crescimento do número de mulheres encarceradas no Brasil não mudou o contexto de invisibilidade em que vivem. Diante de tal silêncio, e tendo a percepção de que é em face do feminino e de seu corpo que o sistema de justiça criminal parece expressar sua mais perversa atuação, o Projeto Mulheres pelas Mulheres se propôs a dar voz e visibilidade a essas mulheres. A partir de uma série de entrevistas – com as próprias internas e com as mulheres que visitavam presos nas penitenciárias de Piraquara-PR – foi possível traçar um perfil da mulher encarcerada no Paraná. Entretanto, chamou a atenção a expressiva quantidade de mulheres grávidas e com bebês dentro do sistema. Assim, tendo como base uma epistemologia feminista, foi possível perceber, através dos relatos e de informações a respeito da visita, da revista e das circunstâncias da prisão de determinadas mulheres, um padrão, uma série de histórias repetidas. Mulheres grávidas que, nas filas para a visita, recebem ofertas razoáveis de dinheiro em troca de um serviço, cujo sucesso já estaria acertado com os responsáveis pela revista. Em um instante, porém, tornam-se, para o sistema de justiça criminal, traficantes. Mulheres-traficantes que trazem no ventre a paradoxal contradição de serem mulheres-traficantes-grávidas, subvertendo a ordem de gênero e os papeis naturalmente estabelecidos, caracterizando aquilo que, simbolicamente, não se admite: que uma criminosa seja, também, mãe.

  3. Immunochemical analysis of Micrococcus lysodeikticus (luteus) F1-ATPase and its subunits.

    Science.gov (United States)

    Urban, C; Salton, M R

    1983-08-31

    The F1-ATPase from Micrococcus lysodeikticus has been purified to 95% protein homogeneity in this laboratory and as all other bacterial F1S, possesses five distinct subunits with molecular weights ranging from 60 000 to 10 000 (Huberman, M. and Salton, M.R.J. (1979) Biochim. Biophys. Acta 547, 230-240). In this communication, we demonstrate the immunochemical reactivities of antibodies to native and SDS-dissociated subunits with the native and dissociated F1-ATPase and show that: (1) the antibodies generated to the native or SDS-dissociated subunits react with the native molecule; (2) all of the subunits comprising the F1 are antigenically unique as determined by crossed immunoelectrophoresis and the Ouchterlony double-diffusion techniques; (3) antibodies to the SDS-denatured individual delta- and epsilon-subunits can be used to destabilize the interaction of these specific subunits with the rest of the native F1; and (4) all subunit antibodies as well as anti-native F1 were found to inhibit ATPase activity to varying degrees, the strongest inhibition being seen with antibodies to the total F1 and anti-alpha- and anti-beta-subunit antibodies. The interaction of specific subunit antibodies may provide a new and novel way to study further and characterize the catalytic portions of F1-ATPases and in general may offer an additional method for the examination of multimeric proteins.

  4. Protein kinase A regulatory subunit distribution in medulloblastoma

    International Nuclear Information System (INIS)

    Mucignat-Caretta, Carla; Denaro, Luca; Redaelli, Marco; D'Avella, Domenico; Caretta, Antonio

    2010-01-01

    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

  5. 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.

  6. A voluntariedade da colaboração premiada e sua relação com a prisão processual do colaborador

    OpenAIRE

    Suxberger, Antonio Henrique Graciano; de Mello, Gabriela Starling Jorge Vieira

    2017-01-01

    A colaboração premiada, meio de obtenção de prova utilizado no enfrentamento das organizações criminosas, exige voluntariedade do colaborador que celebra o acordo jurídico-processual. Na aferição da voluntariedade, muitas são as críticas dirigidas ao acordo celebrado nos casos em que o colaborador se encontre preso. Esses dois institutos – prisão preventiva e colaboração premiada–, embora não possuam relação de causa e efeito, não raro são vistos intrinsecamente ligados na prática. O artigo b...

  7. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography

    OpenAIRE

    Sauguet , Ludovic; Raia , Pierre; Henneke , Ghislaine; Delarue , Marc

    2016-01-01

    International audience; Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has ...

  8. Effect of microinjections of subunits of cAMP-dependent protein kinase on development, proliferation, and RNA synthesis in early embryos of the loach Misgurnus fossilis L

    International Nuclear Information System (INIS)

    Glukhov, A.I.; Benyumov, A.O.; Nesterova, M.V.; Severin, E.S.; Gazaryan, K.G.

    1986-01-01

    The effect of the catalytic and regulatory subunits of cAMP-dependent protein kinase type II on development, proliferation, and RNA synthesis was studied in loach embryos. It was found that injection of the catalytic subunit in a physiological concentration leads to a disturbance in the course of development and inhibits proliferation and RNA synthesis in the embryos. An increase in the concentration of this protein above the physiological level leads to death of the embryos in the first hours of development. Injection of the regulatory subunit stimulated the incorporation of labeled uridine into the acid-insoluble fraction of the embryos, beginning with the gastrula stage. The cell nuclei of loach embryos injected with subunits of protein kinase type II were transplanted into activated loach egg cells: subunits of protein kinase type I had no effect on the ability of nuclei of undetermined loach embryo cells to provide de novo development and their effect was reversible

  9. Persistence of the mitochondrial permeability transition in the absence of subunit c of human ATP synthase.

    Science.gov (United States)

    He, Jiuya; Ford, Holly C; Carroll, Joe; Ding, Shujing; Fearnley, Ian M; Walker, John E

    2017-03-28

    The permeability transition in human mitochondria refers to the opening of a nonspecific channel, known as the permeability transition pore (PTP), in the inner membrane. Opening can be triggered by calcium ions, leading to swelling of the organelle, disruption of the inner membrane, and ATP synthesis, followed by cell death. Recent proposals suggest that the pore is associated with the ATP synthase complex and specifically with the ring of c-subunits that constitute the membrane domain of the enzyme's rotor. The c-subunit is produced from three nuclear genes, ATP5G1 , ATP5G2 , and ATP5G3 , encoding identical copies of the mature protein with different mitochondrial-targeting sequences that are removed during their import into the organelle. To investigate the involvement of the c-subunit in the PTP, we generated a clonal cell, HAP1-A12, from near-haploid human cells, in which ATP5G1 , ATP5G2 , and ATP5G3 were disrupted. The HAP1-A12 cells are incapable of producing the c-subunit, but they preserve the characteristic properties of the PTP. Therefore, the c-subunit does not provide the PTP. The mitochondria in HAP1-A12 cells assemble a vestigial ATP synthase, with intact F 1 -catalytic and peripheral stalk domains and the supernumerary subunits e, f, and g, but lacking membrane subunits ATP6 and ATP8. The same vestigial complex plus associated c-subunits was characterized from human 143B ρ 0 cells, which cannot make the subunits ATP6 and ATP8, but retain the PTP. Therefore, none of the membrane subunits of the ATP synthase that are involved directly in transmembrane proton translocation is involved in forming the PTP.

  10. Assessing subunit dependency of the Plasmodium proteasome using small molecule inhibitors and active site probes.

    Science.gov (United States)

    Li, Hao; van der Linden, Wouter A; Verdoes, Martijn; Florea, Bogdan I; McAllister, Fiona E; Govindaswamy, Kavitha; Elias, Joshua E; Bhanot, Purnima; Overkleeft, Herman S; Bogyo, Matthew

    2014-08-15

    The ubiquitin-proteasome system (UPS) is a potential pathway for therapeutic intervention for pathogens such as Plasmodium, the causative agent of malaria. However, due to the essential nature of this proteolytic pathway, proteasome inhibitors must avoid inhibition of the host enzyme complex to prevent toxic side effects. The Plasmodium proteasome is poorly characterized, making rational design of inhibitors that induce selective parasite killing difficult. In this study, we developed a chemical probe that labels all catalytic sites of the Plasmodium proteasome. Using this probe, we identified several subunit selective small molecule inhibitors of the parasite enzyme complex. Treatment with an inhibitor that is specific for the β5 subunit during blood stage schizogony led to a dramatic decrease in parasite replication while short-term inhibition of the β2 subunit did not affect viability. Interestingly, coinhibition of both the β2 and β5 catalytic subunits resulted in enhanced parasite killing at all stages of the blood stage life cycle and reduced parasite levels in vivo to barely detectable levels. Parasite killing was achieved with overall low host toxicity, something that has not been possible with existing proteasome inhibitors. Our results highlight differences in the subunit dependency of the parasite and human proteasome, thus providing a strategy for development of potent antimalarial drugs with overall low host toxicity.

  11. In Search of Small Molecule Inhibitors Targeting the Flexible CK2 Subunit Interface

    Directory of Open Access Journals (Sweden)

    Benoît Bestgen

    2017-02-01

    Full Text Available Protein kinase CK2 is a tetrameric holoenzyme composed of two catalytic (α and/or α’ subunits and two regulatory (β subunits. Crystallographic data paired with fluorescence imaging techniques have suggested that the formation of the CK2 holoenzyme complex within cells is a dynamic process. Although the monomeric CK2α subunit is endowed with a constitutive catalytic activity, many of the plethora of CK2 substrates are exclusively phosphorylated by the CK2 holoenzyme. This means that the spatial and high affinity interaction between CK2α and CK2β subunits is critically important and that its disruption may provide a powerful and selective way to block the phosphorylation of substrates requiring the presence of CK2β. In search of compounds inhibiting this critical protein–protein interaction, we previously designed an active cyclic peptide (Pc derived from the CK2β carboxy-terminal domain that can efficiently antagonize the CK2 subunit interaction. To understand the functional significance of this interaction, we generated cell-permeable versions of Pc, exploring its molecular mechanisms of action and the perturbations of the signaling pathways that it induces in intact cells. The identification of small molecules inhibitors of this critical interaction may represent the first-choice approach to manipulate CK2 in an unconventional way.

  12. Crystal structure of the bacterial luciferase/flavin complex provides insight into the function of the beta subunit.

    Science.gov (United States)

    Campbell, Zachary T; Weichsel, Andrzej; Montfort, William R; Baldwin, Thomas O

    2009-07-07

    Bacterial luciferase from Vibrio harveyi is a heterodimer composed of a catalytic alpha subunit and a homologous but noncatalytic beta subunit. Despite decades of enzymological investigation, structural evidence defining the active center has been elusive. We report here the crystal structure of V. harveyi luciferase bound to flavin mononucleotide (FMN) at 2.3 A. The isoalloxazine ring is coordinated by an unusual cis-Ala-Ala peptide bond. The reactive sulfhydryl group of Cys106 projects toward position C-4a, the site of flavin oxygenation. This structure also provides the first data specifying the conformations of a mobile loop that is crystallographically disordered in both prior crystal structures [(1995) Biochemistry 34, 6581-6586; (1996) J. Biol. Chem. 271, 21956 21968]. This loop appears to be a boundary between solvent and the active center. Within this portion of the protein, a single contact was observed between Phe272 of the alpha subunit, not seen in the previous structures, and Tyr151 of the beta subunit. Substitutions at position 151 on the beta subunit caused reductions in activity and total quantum yield. Several of these mutants were found to have decreased affinity for reduced flavin mononucleotide (FMNH(2)). These findings partially address the long-standing question of how the beta subunit stabilizes the active conformation of the alpha subunit, thereby participating in the catalytic mechanism.

  13. The testis-specific Cα2 subunit of PKA is kinetically indistinguishable from the common Cα1 subunit of PKA

    Directory of Open Access Journals (Sweden)

    Herberg Friedrich W

    2011-08-01

    Full Text Available Abstract Background The two variants of the α-form of the catalytic (C subunit of protein kinase A (PKA, designated Cα1 and Cα2, are encoded by the PRKACA gene. Whereas Cα1 is ubiquitous, Cα2 expression is restricted to the sperm cell. Cα1 and Cα2 are encoded with different N-terminal domains. In Cα1 but not Cα2 the N-terminal end introduces three sites for posttranslational modifications which include myristylation at Gly1, Asp-specific deamidation at Asn2 and autophosphorylation at Ser10. Previous reports have implicated specific biological features correlating with these modifications on Cα1. Since Cα2 is not modified in the same way as Cα1 we tested if they have distinct biochemical activities that may be reflected in different biological properties. Results We show that Cα2 interacts with the two major forms of the regulatory subunit (R of PKA, RI and RII, to form cAMP-sensitive PKAI and PKAII holoenzymes both in vitro and in vivo as is also the case with Cα1. Moreover, using Surface Plasmon Resonance (SPR, we show that the interaction patterns of the physiological inhibitors RI, RII and PKI were comparable for Cα2 and Cα1. This is also the case for their potency to inhibit catalytic activities of Cα2 and Cα1. Conclusion We conclude that the regulatory complexes formed with either Cα1 or Cα2, respectively, are indistinguishable.

  14. Global Proteome Analysis Identifies Active Immunoproteasome Subunits in Human Platelets*

    Science.gov (United States)

    Klockenbusch, Cordula; Walsh, Geraldine M.; Brown, Lyda M.; Hoffman, Michael D.; Ignatchenko, Vladimir; Kislinger, Thomas; Kast, Juergen

    2014-01-01

    The discovery of new functions for platelets, particularly in inflammation and immunity, has expanded the role of these anucleate cell fragments beyond their primary hemostatic function. Here, four in-depth human platelet proteomic data sets were generated to explore potential new functions for platelets based on their protein content and this led to the identification of 2559 high confidence proteins. During a more detailed analysis, consistently high expression of the proteasome was discovered, and the composition and function of this complex, whose role in platelets has not been thoroughly investigated, was examined. Data set mining resulted in identification of nearly all members of the 26S proteasome in one or more data sets, except the β5 subunit. However, β5i, a component of the immunoproteasome, was identified. Biochemical analyses confirmed the presence of all catalytically active subunits of the standard 20S proteasome and immunoproteasome in human platelets, including β5, which was predominantly found in its precursor form. It was demonstrated that these components were assembled into the proteasome complex and that standard proteasome as well as immunoproteasome subunits were constitutively active in platelets. These findings suggest potential new roles for platelets in the immune system. For example, the immunoproteasome may be involved in major histocompatibility complex I (MHC I) peptide generation, as the MHC I machinery was also identified in our data sets. PMID:25146974

  15. Global proteome analysis identifies active immunoproteasome subunits in human platelets.

    Science.gov (United States)

    Klockenbusch, Cordula; Walsh, Geraldine M; Brown, Lyda M; Hoffman, Michael D; Ignatchenko, Vladimir; Kislinger, Thomas; Kast, Juergen

    2014-12-01

    The discovery of new functions for platelets, particularly in inflammation and immunity, has expanded the role of these anucleate cell fragments beyond their primary hemostatic function. Here, four in-depth human platelet proteomic data sets were generated to explore potential new functions for platelets based on their protein content and this led to the identification of 2559 high confidence proteins. During a more detailed analysis, consistently high expression of the proteasome was discovered, and the composition and function of this complex, whose role in platelets has not been thoroughly investigated, was examined. Data set mining resulted in identification of nearly all members of the 26S proteasome in one or more data sets, except the β5 subunit. However, β5i, a component of the immunoproteasome, was identified. Biochemical analyses confirmed the presence of all catalytically active subunits of the standard 20S proteasome and immunoproteasome in human platelets, including β5, which was predominantly found in its precursor form. It was demonstrated that these components were assembled into the proteasome complex and that standard proteasome as well as immunoproteasome subunits were constitutively active in platelets. These findings suggest potential new roles for platelets in the immune system. For example, the immunoproteasome may be involved in major histocompatibility complex I (MHC I) peptide generation, as the MHC I machinery was also identified in our data sets. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. SHORT COMMUNICATION CATALYTIC KINETIC ...

    African Journals Online (AJOL)

    IV) catalyzes the discoloring reaction of DBS-arsenazo oxidized by potassium bromate, a new catalytic kinetic spectrophotometric method for the determination of trace titanium (IV) was developed. The linear range of the determination of ...

  17. Catalytic distillation process

    Science.gov (United States)

    Smith, L.A. Jr.

    1982-06-22

    A method is described 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.

  18. Catalytic distillation structure

    Science.gov (United States)

    Smith, L.A. Jr.

    1984-04-17

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

  19. 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.

    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

  20. Catalytic nanoporous membranes

    Science.gov (United States)

    Pellin, Michael J; Hryn, John N; Elam, Jeffrey W

    2013-08-27

    A nanoporous catalytic membrane which displays several unique features Including pores which can go through the entire thickness of the membrane. The membrane has a higher catalytic and product selectivity than conventional catalysts. Anodic aluminum oxide (AAO) membranes serve as the catalyst substrate. This substrate is then subjected to Atomic Layer Deposition (ALD), which allows the controlled narrowing of the pores from 40 nm to 10 nm in the substrate by deposition of a preparatory material. Subsequent deposition of a catalytic layer on the inner surfaces of the pores reduces pore sizes to less than 10 nm and allows for a higher degree of reaction selectivity. The small pore sizes allow control over which molecules enter the pores, and the flow-through feature can allow for partial oxidation of reactant species as opposed to complete oxidation. A nanoporous separation membrane, produced by ALD is also provided for use in gaseous and liquid separations. The membrane has a high flow rate of material with 100% selectivity. Also provided is a method for producing a catalytic membrane having flow-through pores and discreet catalytic clusters adhering to the inside surfaces of the pores.

  1. Steam reformer with catalytic combustor

    Science.gov (United States)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  2. Catalytic pyrolysis of hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Vail' eva, N A; Buyanov, R A

    1979-01-01

    Catalytic pyrolysis of petroleum fractions (undecane) was performed with the object of clarifying such questions as the mechanism of action of the catalyst, the concepts of activity and selectivity of the catalyst, the role of transport processes, the temperature ranges and limitations of the catalytic process, the effect of the catalyst on secondary processes, and others. Catalysts such as quartz, MgO, Al/sub 2/O/sub 3/, were used. Analysis of the experimental findings and the fact that the distribution of products is independent of the nature of the surface, demonstrate that the pyrolysis of hydrocarbons in the presence of catalysts is based on the heterogeneous-homogeneous radical-chain mechanism of action, and that the role of the catalysts reduces to increasing the concentration of free radicals. The concept of selectivity cannot be applied to catalysts here, since they do not affect the mechanism of the unfolding of the process of pyrolysis and their role consists solely in initiating the process. In catalytic pyrolysis the concepts of kinetic and diffusive domains of unfolding of the catalytic reaction do not apply, and only the outer surface of the catalyst is engaged, whereas the inner surface merely promotes deletorious secondary processes reducing the selectivity of the process and the activity of the catalyst. 6 references, 2 figures.

  3. 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...

  4. CATALYTIC KINETIC SPECTROPHOTOMETRIC DETERMINATION ...

    African Journals Online (AJOL)

    Preferred Customer

    acetylchlorophosphonazo(CPApA) by hydrogen peroxide in 0.10 M phosphoric acid. A novel catalytic kinetic-spectrophotometric method is proposed for the determination of copper based on this principle. Copper(II) can be determined spectrophotometrically ...

  5. Catalytic methanol dissociation

    International Nuclear Information System (INIS)

    Alcinikov, Y.; Fainberg, V.; Garbar, A.; Gutman, M.; Hetsroni, G.; Shindler, Y.; Tatrtakovsky, L.; Zvirin, Y.

    1998-01-01

    Results of the methanol dissociation study on copper/potassium catalyst with alumina support at various temperatures are presented. The following gaseous and liquid products at. The catalytic methanol dissociation is obtained: hydrogen, carbon monoxide, carbon dioxide, methane, and dimethyl ether. Formation rates of these products are discussed. Activation energies of corresponding reactions are calculated

  6. Subunit Stoichiometry of Human Muscle Chloride Channels

    OpenAIRE

    Fahlke, Christoph; Knittle, Timothy; Gurnett, Christina A.; Campbell, Kevin P.; George, Alfred L.

    1997-01-01

    Voltage-gated Cl? channels belonging to the ClC family appear to function as homomultimers, but the number of subunits needed to form a functional channel is controversial. To determine subunit stoichiometry, we constructed dimeric human skeletal muscle Cl? channels in which one subunit was tagged by a mutation (D136G) that causes profound changes in voltage-dependent gating. Sucrose-density gradient centrifugation experiments indicate that both monomeric and dimeric hClC-1 channels in their ...

  7. Structural insights into methyltransferase KsgA function in 30S ribosomal subunit biogenesis.

    Science.gov (United States)

    Boehringer, Daniel; O'Farrell, Heather C; Rife, Jason P; Ban, Nenad

    2012-03-23

    The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3'-terminal helix 45 of the 16 S ribosomal RNA (rRNA). KsgA recognizes its substrate adenosine residues only in the context of a near mature 30S subunit and is required for the efficient processing of the rRNA termini during ribosome biogenesis. Here, we present the cryo-EM structure of KsgA bound to a nonmethylated 30S ribosomal subunit. The structure reveals that KsgA binds to the 30S platform with the catalytic N-terminal domain interacting with substrate adenosine residues in helix 45 and the C-terminal domain making extensive contacts to helix 27 and helix 24. KsgA excludes the penultimate rRNA helix 44 from adopting its position in the mature 30S subunit, blocking the formation of the decoding site and subunit joining. We suggest that the activation of methyltransferase activity and subsequent dissociation of KsgA control conformational changes in helix 44 required for final rRNA processing and translation initiation.

  8. Structural Insights into Methyltransferase KsgA Function in 30S Ribosomal Subunit Biogenesis*

    Science.gov (United States)

    Boehringer, Daniel; O'Farrell, Heather C.; Rife, Jason P.; Ban, Nenad

    2012-01-01

    The assembly of the ribosomal subunits is facilitated by ribosome biogenesis factors. The universally conserved methyltransferase KsgA modifies two adjacent adenosine residues in the 3′-terminal helix 45 of the 16 S ribosomal RNA (rRNA). KsgA recognizes its substrate adenosine residues only in the context of a near mature 30S subunit and is required for the efficient processing of the rRNA termini during ribosome biogenesis. Here, we present the cryo-EM structure of KsgA bound to a nonmethylated 30S ribosomal subunit. The structure reveals that KsgA binds to the 30S platform with the catalytic N-terminal domain interacting with substrate adenosine residues in helix 45 and the C-terminal domain making extensive contacts to helix 27 and helix 24. KsgA excludes the penultimate rRNA helix 44 from adopting its position in the mature 30S subunit, blocking the formation of the decoding site and subunit joining. We suggest that the activation of methyltransferase activity and subsequent dissociation of KsgA control conformational changes in helix 44 required for final rRNA processing and translation initiation. PMID:22308031

  9. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Concentric catalytic combustor

    Science.gov (United States)

    Bruck, Gerald J [Oviedo, FL; Laster, Walter R [Oviedo, FL

    2009-03-24

    A catalytic combustor (28) includes a tubular pressure boundary element (90) having a longitudinal flow axis (e.g., 56) separating a first portion (94) of a first fluid flow (e.g., 24) from a second portion (95) of the first fluid flow. The pressure boundary element includes a wall (96) having a plurality of separate longitudinally oriented flow paths (98) annularly disposed within the wall and conducting respective portions (100, 101) of a second fluid flow (e.g., 26) therethrough. A catalytic material (32) is disposed on a surface (e.g., 102, 103) of the pressure boundary element exposed to at least one of the first and second portions of the first fluid flow.

  11. Identification of novel transcriptional regulators of PKA subunits in Saccharomyces cerevisiae by quantitative promoter-reporter screening.

    Science.gov (United States)

    Pautasso, Constanza; Reca, Sol; Chatfield-Reed, Kate; Chua, Gordon; Galello, Fiorella; Portela, Paula; Zaremberg, Vanina; Rossi, Silvia

    2016-08-01

    The cAMP-dependent protein kinase (PKA) signaling is a broad pathway that plays important roles in the transduction of environmental signals triggering precise physiological responses. However, how PKA achieves the cAMP-signal transduction specificity is still in study. The regulation of expression of subunits of PKA should contribute to the signal specificity. Saccharomyces cerevisiae PKA holoenzyme contains two catalytic subunits encoded by TPK1, TPK2 and TPK3 genes, and two regulatory subunits encoded by BCY1 gene. We studied the activity of these gene promoters using a fluorescent reporter synthetic genetic array screen, with the goal of systematically identifying novel regulators of expression of PKA subunits. Gene ontology analysis of the identified modulators showed enrichment not only in the category of transcriptional regulators, but also in less expected categories such as lipid and phosphate metabolism. Inositol, choline and phosphate were identified as novel upstream signals that regulate transcription of PKA subunit genes. The results support the role of transcription regulation of PKA subunits in cAMP specificity signaling. Interestingly, known targets of PKA phosphorylation are associated with the identified pathways opening the possibility of a reciprocal regulation. PKA would be coordinating different metabolic pathways and these processes would in turn regulate expression of the kinase subunits. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Catalytic exhaust control

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, H

    1973-09-01

    Recent achievements and problems in the development of exhaust control devices in the USA are reviewed. To meet the 1976 emission standards, catalytic systems for the oxidation of carbon monoxide and hydrocarbons and for the reduction of nitrogen oxides to nitrogen and water are needed. While oxidizing catalysts using platinum, palladium, copper, vanadium, and chromium appplied on alumina or ceramic materials are more or less effective in emission control, there are no catalytic devices for the reduction of nitrogen oxides with the required useful life of 25,000 to 50,000 miles as yet available. In the case of platinum catalysts on monolithic supports, the operating temperature of 650 to 750/sup 0/C as required for the oxidation process may cause inactivation of the catalysts and fusion of the support material. The oxidation of CO and hydrocarbons is inhibited by high concentrations of CO, nitric oxide, and hydrocarbons. The use of catalytic converters requires the use of lead-free or low-lead gasoline. The nitrogen oxides conversion efficiency is considerably influenced by the oxygen-to-CO ratio of the exhaust gas, which makes limitation of this ratio necessary.

  13. Role of the Rubisco Small Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Spreitzer, Robert Joseph [Univ. of Nebraska, Lincoln, NE (United States)

    2016-11-05

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the rate-limiting step of CO2 fixation in photosynthesis. However, it is a slow enzyme, and O2 competes with CO2 at the active site. Oxygenation initiates the photorespiratory pathway, which also results in the loss of CO2. If carboxylation could be increased or oxygenation decreased, an increase in net CO2 fixation would be realized. Because Rubisco provides the primary means by which carbon enters all life on earth, there is much interest in engineering Rubisco to increase the production of food and renewable energy. Rubisco is located in the chloroplasts of plants, and it is comprised of two subunits. Much is known about the chloroplast-gene-encoded large subunit (rbcL gene), which contains the active site, but much less is known about the role of the nuclear-gene-encoded small subunit in Rubisco function (rbcS gene). Both subunits are coded by multiple genes in plants, which makes genetic engineering difficult. In the eukaryotic, green alga Chlamydomonas reinhardtii, it has been possible to eliminate all the Rubisco genes. These Rubisco-less mutants can be maintained by providing acetate as an alternative carbon source. In this project, focus has been placed on determining whether the small subunit might be a better genetic-engineering target for improving Rubisco. Analysis of a variable-loop structure (βA-βB loop) of the small subunit by genetic selection, directed mutagenesis, and construction of chimeras has shown that the small subunit can influence CO2/O2 specificity. X-ray crystal structures of engineered chimeric-loop enzymes have indicated that additional residues and regions of the small subunit may also contribute to Rubisco function. Structural dynamics of the small-subunit carboxyl terminus was also investigated. Alanine-scanning mutagenesis of the most-conserved small-subunit residues has identified a

  14. Permeability transition in human mitochondria persists in the absence of peripheral stalk subunits of ATP synthase.

    Science.gov (United States)

    He, Jiuya; Carroll, Joe; Ding, Shujing; Fearnley, Ian M; Walker, John E

    2017-08-22

    The opening of a nonspecific channel, known as the permeability transition pore (PTP), in the inner membranes of mitochondria can be triggered by calcium ions, leading to swelling of the organelle, disruption of the inner membrane and ATP synthesis, and cell death. Pore opening can be inhibited by cyclosporin A mediated via cyclophilin D. It has been proposed that the pore is associated with the dimeric ATP synthase and the oligomycin sensitivity conferral protein (OSCP), a component of the enzyme's peripheral stalk, provides the site at which cyclophilin D interacts. Subunit b contributes a central α-helical structure to the peripheral stalk, extending from near the top of the enzyme's catalytic domain and crossing the membrane domain of the enzyme via two α-helices. We investigated the possible involvement of the subunit b and the OSCP in the PTP by generating clonal cells, HAP1-Δb and HAP1-ΔOSCP, lacking the membrane domain of subunit b or the OSCP, respectively, in which the corresponding genes, ATP5F1 and ATP5O , had been disrupted. Both cell lines preserve the characteristic properties of the PTP; therefore, the membrane domain of subunit b does not contribute to the PTP, and the OSCP does not provide the site of interaction with cyclophilin D. The membrane subunits ATP6, ATP8, and subunit c have been eliminated previously from possible participation in the PTP; thus, the only subunits of ATP synthase that could participate in pore formation are e, f, g, diabetes-associated protein in insulin-sensitive tissues (DAPIT), and the 6.8-kDa proteolipid.

  15. Human Pol ζ purified with accessory subunits is active in translesion DNA synthesis and complements Pol η in cisplatin bypass.

    Science.gov (United States)

    Lee, Young-Sam; Gregory, Mark T; Yang, Wei

    2014-02-25

    DNA polymerase ζ (Pol ζ) is a eukaryotic B-family DNA polymerase that specializes in translesion synthesis and is essential for normal embryogenesis. At a minimum, Pol ζ consists of a catalytic subunit Rev3 and an accessory subunit Rev7. Mammalian Rev3 contains >3,000 residues and is twice as large as the yeast homolog. To date, no vertebrate Pol ζ has been purified for biochemical characterization. Here we report purification of a series of human Rev3 deletion constructs expressed in HEK293 cells and identification of a minimally catalytically active human Pol ζ variant. With a tagged form of an active Pol ζ variant, we isolated two additional accessory subunits of human Pol ζ, PolD2 and PolD3. The purified four-subunit Pol ζ4 (Rev3-Rev7-PolD2-PolD3) is much more efficient and more processive at bypassing a 1,2-intrastrand d(GpG)-cisplatin cross-link than the two-subunit Pol ζ2 (Rev3-Rev7). We show that complete bypass of cisplatin lesions requires Pol η to insert dCTP opposite the 3' guanine and Pol ζ4 to extend the primers.

  16. 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....

  17. 28 CFR 51.6 - Political subunits.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Political subunits. 51.6 Section 51.6 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) PROCEDURES FOR THE ADMINISTRATION OF SECTION 5 OF THE VOTING RIGHTS ACT OF 1965, AS AMENDED General Provisions § 51.6 Political subunits. All political...

  18. Effect of dexamethasone on skeletal muscle Na+,K+ pump subunit specific expression and K+ homeostasis during exercise in humans

    DEFF Research Database (Denmark)

    Nordsborg, Nikolai; Ovesen, Jakob; Thomassen, Martin

    2008-01-01

    The effect of dexamethasone on Na(+),K(+) pump subunit expression and muscle exchange of K(+) during exercise in humans was investigated. Nine healthy male subjects completed a randomized double blind placebo controlled protocol, with ingestion of dexamethasone (Dex: 2 x 2 mg per day) or placebo...... (Pla) for 5 days. Na(+),K(+) pump catalytic alpha1 and alpha2 subunit expression was approximately 17% higher (P ...). The results indicate that an increased Na(+),K(+) pump expression per se is of importance for thigh K(+) reuptake at the onset of low and moderate intensity exercise, but less important during high intensity exercise....

  19. 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

    2015-05-22

    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. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. 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

  1. Catalytic biomass pyrolysis process

    Science.gov (United States)

    Dayton, David C.; Gupta, Raghubir P.; Turk, Brian S.; Kataria, Atish; Shen, Jian-Ping

    2018-04-17

    Described herein are processes for converting a biomass starting material (such as lignocellulosic materials) into a low oxygen containing, stable liquid intermediate that can be refined to make liquid hydrocarbon fuels. More specifically, the process can be a catalytic biomass pyrolysis process wherein an oxygen removing catalyst is employed in the reactor while the biomass is subjected to pyrolysis conditions. The stream exiting the pyrolysis reactor comprises bio-oil having a low oxygen content, and such stream may be subjected to further steps, such as separation and/or condensation to isolate the bio-oil.

  2. Catalytic reforming methods

    Science.gov (United States)

    Tadd, Andrew R; Schwank, Johannes

    2013-05-14

    A catalytic reforming method is disclosed herein. The method includes sequentially supplying a plurality of feedstocks of variable compositions to a reformer. The method further includes adding a respective predetermined co-reactant to each of the plurality of feedstocks to obtain a substantially constant output from the reformer for the plurality of feedstocks. The respective predetermined co-reactant is based on a C/H/O atomic composition for a respective one of the plurality of feedstocks and a predetermined C/H/O atomic composition for the substantially constant output.

  3. Reduction and Methyl Transfer Kinetics of the Alpha Subunit from Acetyl-Coenzyme A Synthase

    Energy Technology Data Exchange (ETDEWEB)

    Xiangshi Tan; Christopher Sewell; Qingwu Yang; Paul A. Lindahl

    2003-01-15

    OAK-B135 Stopped-flow was used to evaluate the methylation and reduction kinetics of the isolated alpha subunit of acetyl-Coenzyme A synthase from Moorella thermoacetica. This catalytically active subunit contains a novel Ni-X-Fe4S4 cluster and a putative unidentified n =2 redox site called D. The D-site must be reduced for a methyl group to transfer from a corrinoid-iron-sulfur protein, a key step in the catalytic synthesis of acetyl-CoA. The Fe4S4 component of this cluster is also redox active, raising the possibility that it is the D-site or a portion thereof. Results presented demonstrate that the D-site reduces far faster than the Fe4S4 component, effectively eliminating this possibility. Rather, this component may alter catalytically important properties of the Ni center. The D-site is reduced through a pathway that probably does not involve the Fe4S4 component of this active-site cluster.

  4. Deletion of individual Ku subunits in mice causes an NHEJ-independent phenotype potentially by altering apurinic/apyrimidinic site repair

    NARCIS (Netherlands)

    Y.J. Choi (Yong Jun); H. Li (Han); M.Y. Son (Mi Young); X.-H. Wang (Xiao-Hong); J.L. Fornsaglio (Jamie L.); R.W. Sobol (Robert W.); M. Lee (Moonsook); J. Vijg (Jan); S. Imholz (Sandra); M.E.T. Dollé (Martijn); H. van Steeg (Harry); E. Reiling (Erwin); P. Hasty (Paul)

    2014-01-01

    textabstractKu70 and Ku80 form a heterodimer called Ku that forms a holoenzyme with DNA dependent-protein kinase catalytic subunit (DNA-PKCS) to repair DNA double strand breaks (DSBs) through the nonhomologous end joining (NHEJ) pathway. As expected mutating these genes in mice caused a similar DSB

  5. 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

  6. 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.

  7. Subcellular compartmentation, interdependency and dynamics of the cyclic AMP-dependent PKA subunits during pathogenic differentiation in rice blast.

    Science.gov (United States)

    Selvaraj, Poonguzhali; Tham, Hong Fai; Ramanujam, Ravikrishna; Naqvi, Naweed I

    2017-08-01

    The cAMP-dependent PKA signalling plays a central role in growth, asexual development and pathogenesis in fungal pathogens. Here, we functionally characterised RPKA, the regulatory subunit of cAMP/PKA and studied the dynamics and organisation of the PKA subunits in the rice blast pathogen Magnaporthe oryzae. The RPKA subunit was essential for proper vegetative growth, asexual sporulation and surface hydrophobicity in M. oryzae. A spontaneous suppressor mutation, SMR19, that restored growth and conidiation in the RPKA deletion mutant was isolated and characterised. SMR19 enhanced conidiation and appressorium formation but failed to suppress the pathogenesis defects in rpkAΔ. The PKA activity was undetectable in the mycelial extracts of SMR19, which showed a single mutation (val242leu) in the highly conserved active site of the catalytic subunit (CPKA) of cAMP/PKA. The two subunits of cAMP/PKA showed different subcellular localisation patterns with RpkA being predominantly nucleocytoplasmic in conidia, while CpkA was largely cytosolic and/or vesicular. The CpkA anchored RpkA in cytoplasmic vesicles, and localisation of PKA in the cytoplasm was governed by CpkA in a cAMP-dependant or independent manner. We show that there exists a tight regulation of PKA subunits at the level of transcription, and the cAMP signalling is differentially compartmentalised in a stage-specific manner in rice blast. © 2017 John Wiley & Sons Ltd.

  8. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    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 ...

  9. Acetylcholine Receptor: Complex of Homologous Subunits

    Science.gov (United States)

    Raftery, Michael A.; Hunkapiller, Michael W.; Strader, Catherine D.; Hood, Leroy E.

    1980-06-01

    The acetylcholine receptor from the electric ray Torpedo californica is composed of five subunits; two are identical and the other three are structurally related to them. Microsequence analysis of the four polypeptides demonstrates amino acid homology among the subunits. Further sequence analysis of both membrane-bound and Triton-solubilized, chromatographically purified receptor gave the stoichiometry of the four subunits (40,000:50,000:60,000:65,000 daltons) as 2:1:1:1, indicating that this protein is a pentameric complex with a molecular weight of 255,000 daltons. Genealogical analysis suggests that divergence from a common ancestral gene occurred early in the evolution of the receptor. This shared ancestry argues that each of the four subunits plays a functional role in the receptor's physiological action.

  10. Leptin and insulin engage specific PI3K subunits in hypothalamic SF1 neurons

    Directory of Open Access Journals (Sweden)

    Jong-Woo Sohn

    2016-08-01

    Full Text Available Objective: The ventromedial hypothalamic nucleus (VMH regulates energy balance and glucose homeostasis. Leptin and insulin exert metabolic effects via their cognate receptors expressed by the steroidogenic factor 1 (SF1 neurons within the VMH. However, detailed cellular mechanisms involved in the regulation of these neurons by leptin and insulin remain to be identified. Methods: We utilized genetically-modified mouse models and performed patch-clamp electrophysiology experiments to resolve this issue. Results: We identified distinct populations of leptin-activated and leptin-inhibited SF1 neurons. In contrast, insulin uniformly inhibited SF1 neurons. Notably, we found that leptin-activated, leptin-inhibited, and insulin-inhibited SF1 neurons are distinct subpopulations within the VMH. Leptin depolarization of SF1 neuron also required the PI3K p110β catalytic subunit. This effect was mediated by the putative transient receptor potential C (TRPC channel. On the other hand, hyperpolarizing responses of SF1 neurons by leptin and insulin required either of the p110α or p110β catalytic subunits, and were mediated by the putative ATP-sensitive K+ (KATP channel. Conclusions: Our results demonstrate that specific PI3K catalytic subunits are responsible for the acute effects of leptin and insulin on VMH SF1 neurons, and provide insights into the cellular mechanisms of leptin and insulin action on VMH SF1 neurons that regulate energy balance and glucose homeostasis. Author Video: Author Video Watch what authors say about their articles Keywords: Cellular mechanism, Conditional knockout mouse, Patch clamp technique, Functional heterogeneity, Homeostasis

  11. Catalytic detritiation of water

    International Nuclear Information System (INIS)

    Rogers, M.L.; Lamberger, P.H.; Ellis, R.E.; Mills, T.K.

    1977-01-01

    A pilot-scale system has been used at Mound Laboratory to investigate the catalytic detritiation of water. A hydrophobic, precious metal catalyst is used to promote the exchange of tritium between liquid water and gaseous hydrogen at 60 0 C. Two columns are used, each 7.5 m long by 2.5 cm ID and packed with catalyst. Water flow is 5-10 cm 3 /min and countercurrent hydrogen flow is 9,000-12,000 cm 3 /min. The equipment, except for the columns, is housed in an inert atmosphere glovebox and is computer controlled. The hydrogen is obtained by electrolysis of a portion of the water stream. Enriched gaseous tritium is withdrawn for further enrichment. A description of the system is included along with an outline of its operation. Recent experimental data are discussed

  12. 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.

  13. Baicalin and scutellarin are proteasome inhibitors that specifically target chymotrypsin-like catalytic activity.

    Science.gov (United States)

    Wu, Yi-Xin; Sato, Eiji; Kimura, Wataru; Miura, Naoyuki

    2013-09-01

    Baicalin and scutellarin are the major active principal flavonoids extracted from the Chinese herbal medicines Scutellaria baicalensis and Erigeron breviscapus (Vant.) Hand-Mazz. It has recently been reported that baicalin and scutellarin have antitumor activity. However, the mechanisms of action are unknown. We previously reported that some flavonoids have a specific role in the inhibition of the activity of proteasome subunits and induced apoptosis in tumor cells. To further investigate these pharmacological effects, we examined the inhibitory activity of baicalin and scutellarin on the extracted proteasomes from mice and cancer cells. Using fluorogenic substrates for proteasome catalytic subunits, we found that baicalin and scutellarin specifically inhibited chymotrypsin-like activity but did not inhibit trypsin-like and peptidyl-glutamyl peptide hydrolyzing activities. These data suggested that baicalin and scutellarin specifically inhibit chymotrypsin-like catalytic activity in the proteasome. Copyright © 2012 John Wiley & Sons, Ltd.

  14. Suppressor mutations identify amino acids in PAA-1/PR65 that facilitate regulatory RSA-1/B″ subunit targeting of PP2A to centrosomes in C. elegans.

    Science.gov (United States)

    Lange, Karen I; Heinrichs, Jeffrey; Cheung, Karen; Srayko, Martin

    2013-01-15

    Protein phosphorylation and dephosphorylation is a key mechanism for the spatial and temporal regulation of many essential developmental processes and is especially prominent during mitosis. The multi-subunit protein phosphatase 2A (PP2A) enzyme plays an important, yet poorly characterized role in dephosphorylating proteins during mitosis. PP2As are heterotrimeric complexes comprising a catalytic, structural, and regulatory subunit. Regulatory subunits are mutually exclusive and determine subcellular localization and substrate specificity of PP2A. At least 3 different classes of regulatory subunits exist (termed B, B', B″) but there is no obvious similarity in primary sequence between these classes. Therefore, it is not known how these diverse regulatory subunits interact with the same holoenzyme to facilitate specific PP2A functions in vivo. The B″ family of regulatory subunits is the least understood because these proteins lack conserved structural domains. RSA-1 (regulator of spindle assembly) is a regulatory B″ subunit required for mitotic spindle assembly in Caenorhabditis elegans. In order to address how B″ subunits interact with the PP2A core enzyme, we focused on a conditional allele, rsa-1(or598ts), and determined that this mutation specifically disrupts the protein interaction between RSA-1 and the PP2A structural subunit, PAA-1. Through genetic screening, we identified a putative interface on the PAA-1 structural subunit that interacts with a defined region of RSA-1/B″. In the context of previously published results, these data propose a mechanism of how different PP2A B-regulatory subunit families can bind the same holoenzyme in a mutually exclusive manner, to perform specific tasks in vivo.

  15. Suppressor mutations identify amino acids in PAA-1/PR65 that facilitate regulatory RSA-1/B″ subunit targeting of PP2A to centrosomes in C. elegans

    Directory of Open Access Journals (Sweden)

    Karen I. Lange

    2012-11-01

    Protein phosphorylation and dephosphorylation is a key mechanism for the spatial and temporal regulation of many essential developmental processes and is especially prominent during mitosis. The multi-subunit protein phosphatase 2A (PP2A enzyme plays an important, yet poorly characterized role in dephosphorylating proteins during mitosis. PP2As are heterotrimeric complexes comprising a catalytic, structural, and regulatory subunit. Regulatory subunits are mutually exclusive and determine subcellular localization and substrate specificity of PP2A. At least 3 different classes of regulatory subunits exist (termed B, B′, B″ but there is no obvious similarity in primary sequence between these classes. Therefore, it is not known how these diverse regulatory subunits interact with the same holoenzyme to facilitate specific PP2A functions in vivo. The B″ family of regulatory subunits is the least understood because these proteins lack conserved structural domains. RSA-1 (regulator of spindle assembly is a regulatory B″ subunit required for mitotic spindle assembly in Caenorhabditis elegans. In order to address how B″ subunits interact with the PP2A core enzyme, we focused on a conditional allele, rsa-1(or598ts, and determined that this mutation specifically disrupts the protein interaction between RSA-1 and the PP2A structural subunit, PAA-1. Through genetic screening, we identified a putative interface on the PAA-1 structural subunit that interacts with a defined region of RSA-1/B″. In the context of previously published results, these data propose a mechanism of how different PP2A B-regulatory subunit families can bind the same holoenzyme in a mutually exclusive manner, to perform specific tasks in vivo.

  16. NADP+ binding to the regulatory subunit of methionine adenosyltransferase II increases intersubunit binding affinity in the hetero-trimer.

    Directory of Open Access Journals (Sweden)

    Beatriz González

    Full Text Available Mammalian methionine adenosyltransferase II (MAT II is the only hetero-oligomer in this family of enzymes that synthesize S-adenosylmethionine using methionine and ATP as substrates. Binding of regulatory β subunits and catalytic α2 dimers is known to increase the affinity for methionine, although scarce additional information about this interaction is available. This work reports the use of recombinant α2 and β subunits to produce oligomers showing kinetic parameters comparable to MAT II purified from several tissues. According to isothermal titration calorimetry data and densitometric scanning of the stained hetero-oligomer bands on denatured gels, the composition of these oligomers is that of a hetero-trimer with α2 dimers associated to single β subunits. Additionally, the regulatory subunit is able to bind NADP(+ with a 1:1 stoichiometry, the cofactor enhancing β to α2-dimer binding affinity. Mutants lacking residues involved in NADP(+ binding and N-terminal truncations of the β subunit were able to oligomerize with α2-dimers, although the kinetic properties appeared altered. These data together suggest a role for both parts of the sequence in the regulatory role exerted by the β subunit on catalysis. Moreover, preparation of a structural model for the hetero-oligomer, using the available crystal data, allowed prediction of the regions involved in β to α2-dimer interaction. Finally, the implications that the presence of different N-terminals in the β subunit could have on MAT II behavior are discussed in light of the recent identification of several splicing forms of this subunit in hepatoma cells.

  17. 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.

  18. Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3 Deficiency Associated With Autoinflammatory Complications

    Directory of Open Access Journals (Sweden)

    Anoop Mistry

    2017-11-01

    Full Text Available G6PC3 deficiency typically causes severe congenital neutropenia, associated with susceptibility to infections, cardiac and urogenital abnormalities. However, here we describe two boys of Pakistani origin who were found to have G6PC3 deficiency due to c.130 C>T mutation, but who have clinical phenotypes that are typical for a systemic autoinflammatory syndrome. The index case presented with combination of unexplained fevers, severe mucosal ulcers, abdominal symptoms, and inflammatory arthritis. He eventually fully responded to anti-TNF therapy. In this study, we show that compared with healthy controls, neutrophils and monocytes from patients have reduced glycolytic reserve. Considering that healthy myeloid cells have been shown to switch their metabolic pathways to glycolysis in response to inflammatory cues, we studied what impact this might have on production of the inflammatory cytokines. We have demonstrated that patients’ monocytes, in response to lipopolysaccharide, show significantly increased production of IL-1β and IL-18, which is NLRP3 inflammasome dependent. Furthermore, additional whole blood assays have also shown an enhanced production of IL-6 and TNF from the patients’ cells. These cases provide further proof that autoinflammatory complications are also seen within the spectrum of primary immune deficiencies, and resulting from a wider dysregulation of the immune responses.

  19. Mutations of the catalytic subunit of RAB3GAP cause Warburg Micro syndrome

    DEFF Research Database (Denmark)

    Aligianis, Irene A; Johnson, Colin A; Gissen, Paul

    2005-01-01

    Warburg Micro syndrome (WARBM1) is a severe autosomal recessive disorder characterized by developmental abnormalities of the eye and central nervous system and by microgenitalia. We identified homozygous inactivating mutations in RAB3GAP, encoding RAB3 GTPase activating protein, a key regulator...

  20. Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3) Deficiency Associated With Autoinflammatory Complications.

    Science.gov (United States)

    Mistry, Anoop; Scambler, Thomas; Parry, David; Wood, Mark; Barcenas-Morales, Gabriela; Carter, Clive; Doffinger, Rainer; Savic, Sinisa

    2017-01-01

    G6PC3 deficiency typically causes severe congenital neutropenia, associated with susceptibility to infections, cardiac and urogenital abnormalities. However, here we describe two boys of Pakistani origin who were found to have G6PC3 deficiency due to c.130 C>T mutation, but who have clinical phenotypes that are typical for a systemic autoinflammatory syndrome. The index case presented with combination of unexplained fevers, severe mucosal ulcers, abdominal symptoms, and inflammatory arthritis. He eventually fully responded to anti-TNF therapy. In this study, we show that compared with healthy controls, neutrophils and monocytes from patients have reduced glycolytic reserve. Considering that healthy myeloid cells have been shown to switch their metabolic pathways to glycolysis in response to inflammatory cues, we studied what impact this might have on production of the inflammatory cytokines. We have demonstrated that patients' monocytes, in response to lipopolysaccharide, show significantly increased production of IL-1β and IL-18, which is NLRP3 inflammasome dependent. Furthermore, additional whole blood assays have also shown an enhanced production of IL-6 and TNF from the patients' cells. These cases provide further proof that autoinflammatory complications are also seen within the spectrum of primary immune deficiencies, and resulting from a wider dysregulation of the immune responses.

  1. 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

  2. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. 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.)

  4. The Subunit Principle in Scar Face Revision.

    Science.gov (United States)

    Elshahat, Ahmed; Lashin, Riham

    2017-06-01

    Facial scaring is considered one of the most difficult cosmetic problems for any plastic surgeon to solve. The condition is more difficult if the direction of the scar is not parallel to relaxed skin tension lines. Attempts to manage this difficult situation included revisions using geometric designs, Z plasties or W plasties to camouflage the straight line visible scaring. The use of long-lasting resorbable sutures was tried too. Recently, the use of botulinum toxin during revision improved the results. Fractional CO2 lasers, microfat grafts, and platelet-rich plasma were added to the armamentarium. The scar is least visible if placed in the junction between the facial subunits. The aim of this study is to investigate the use of the subunit principle to improve the results of scar revision. Four patients were included in this study. Tissue expansion of the intact part of the subunit allowed shifting the scar to the junction between the affected subunit and the adjacent one. Tissue expansion, delivery of the expanders, and advancement of the flaps were successful in all patients. The fact that this is a 2-stage procedure and sacrifices some of the intact skin from the affected facial subunit, makes this technique reserved to patients with ugly facial scars who are ambitious to improve their appearance.

  5. Engineering reactors for catalytic reactions

    Indian Academy of Sciences (India)

    126, No. 2, March 2014, pp. 341–351. c Indian Academy of Sciences. ... enhancement was realized by catalyst design, appropriate choice of reactor, better injection and .... Gas–liquid and liquid–solid transport processes in catalytic reactors.5.

  6. 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

  7. Effect of High-Pressure Treatment on Catalytic and Physicochemical Properties of Pepsin.

    Science.gov (United States)

    Wang, Jianan; Bai, Tenghui; Ma, Yaping; Ma, Hanjun

    2017-10-11

    For a long time, high-pressure treatment has been used to destroy the compact structures of natural proteins in order to promote subsequent enzymatic hydrolysis. However, there are few reports evaluating the feasibility of directly improving the catalytic capability of proteases by using high-pressure treatments. In this study, the effects of high-pressure treatment on the catalytic capacity and structure of pepsin were investigated, and the relationship between its catalytic properties and changes in its physicochemical properties was explored. It was found that high-pressure treatment could lead to changes of the sulfhydryl group/disulfide bond content, hydrophobicity, hydrodynamic radius, intrinsic viscosity, and subunit composition of pepsin, and the conformational change of pepsin resulted in improvement to its enzymatic activity and hydrolysis efficiency, which had an obvious relationship with the high-pressure treatment conditions.

  8. 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

    , moreover, is variably accounted for by changes in Vmax and/or Km, depending on the structure of the peptide substrate. Maximum stimulation with all protein/peptide substrates tested requires the presence of the beta subunit, since the recombinant alpha subunit is much less responsive than CK2 holoenzyme......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...

  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. A conformational switch in the inhibitory gamma-subunit of PDE6 upon enzyme activation by transducin.

    Science.gov (United States)

    Granovsky, A E; Artemyev, N O

    2001-11-06

    In response to light, a photoreceptor G protein, transducin, activates cGMP-phosphodiesterase (PDE6) by displacing the inhibitory gamma-subunits (Pgamma) from the enzyme's catalytic sites. Evidence suggests that the activation of PDE6 involves a conformational change of the key inhibitory C-terminal domain of Pgamma. In this study, the C-terminal region of Pgamma, Pgamma-73-85, has been targeted for Ala-scanning mutagenesis to identify the point-to-point interactions between Pgamma and the PDE6 catalytic subunits and to probe the nature of the conformational change. Pgamma mutants were tested for their ability to inhibit PDE6 and a chimeric PDE5-conePDE6 enzyme containing the Pgamma C-terminus-binding site of cone PDE. This analysis has revealed that in addition to previously characterized Ile86 and Ile87, important inhibitory contact residues of Pgamma include Asn74, His75, and Leu78. The patterns of mutant PDE5-conePDE6 enzyme inhibition suggest the interaction between the PgammaAsn74/His75 sequence and Met758 of the cone PDE6alpha' catalytic subunit. This interaction, and the interaction between the PgammaIle86/Ile87 and PDE6alpha'Phe777/Phe781 residues, is most consistent with an alpha-helical structure of the Pgamma C-terminus. The analysis of activation of PDE6 enzymes containing Pgamma mutants with Ala-substituted transducin-contact residues demonstrated the critical role of PgammaLeu76. Accordingly, we hypothesize that the initial step in PDE6 activation involves an interaction of transducin-alpha with PgammaLeu76. This interaction introduces a bend into the alpha-helical structure of the Pgamma C-terminus, allowing transducin-alpha to further twist the C-terminus thereby uncovering the catalytic pocket of PDE6.

  11. Isolation and characterization of human cDNA clones encoding the α and the α' subunits of casein kinase II

    International Nuclear Information System (INIS)

    Lozeman, F.J.; Litchfield, D.W.; Piening, C.; Takio, Koji; Walsh, K.A.; Krebs, E.G.

    1990-01-01

    Casein kinase II is a widely distributed protein serine/threonine kinase. The holoenzyme appears to be a tetramer, containing two α or α' subunits (or one of each) and two β subunits. Complementary DNA clones encoding the subunits of casein kinase II were isolated from a human T-cell λgt 10 library using cDNA clones isolated from Drosophila melanogasten. One of the human cDNA clones (hT4.1) was 2.2 kb long, including a coding region of 1176 bp preceded by 156 bp (5' untranslated region) and followed by 871 bp (3' untranslated region). The hT4.1 close was nearly identical in size and sequence with a cDNA clone from HepG2 human hepatoma cultured cells. Another of the human T-cell cDNA clones (hT9.1) was 1.8 kb long, containing a coding region of 1053 bp preceded by 171 by (5' untranslated region) and followed by 550 bp (3' untranslated region). Amino acid sequences deduced from these two cDNA clones were about 85% identical. Most of the difference between the two encoded polypeptides was in the carboxy-terminal region, but heterogeneity was distributed throughout the molecules. Partial amino acid sequence was determined in a mixture of α and α' subunits from bovine lung casein kinase II. The bovine sequences aligned with the 2 human cDNA-encoded polypeptides with only 2 discrepancies out of 535 amino acid positions. This confirmed that the two human T-cell cDNA clones encoded the α and α' subunits of casein kinase II. These studies show that there are two distinct catalytic subunits for casein II (α and α') and that the sequence of these subunits is largely conserved between the bovine and the human

  12. Interaction of the regulatory subunit of the cAMP-dependent protein kinase with PATZ1 (ZNF278)

    International Nuclear Information System (INIS)

    Yang, Weng-Lang; Ravatn, Roald; Kudoh, Kazuya; Alabanza, Leah; Chin, Khew-Voon

    2010-01-01

    The effects of cAMP in cell are predominantly mediated by the cAMP-dependent protein kinase (PKA), which is composed of two genetically distinct subunits, catalytic (C) and regulatory (R), forming a tetrameric holoenzyme R 2 C 2 . The only known function for the R subunit is that of inhibiting the activity of the C subunit kinase. It has been shown that overexpression of RIα, but not the C subunit kinase, is associated with neoplastic transformation. In addition, it has also been demonstrated that mutation in the RIα, but not the C subunit is associated with increased resistance to the DNA-damaging anticancer drug cisplatin, thus suggesting that the RIα subunit of PKA may have functions independent of the kinase. We show here that the RIα subunit interacts with a BTB/POZ domain zinc-finger transcription factor, PATZ1 (ZNF278), and co-expression with RIα results in its sequestration in the cytoplasm. The cytoplasmic/nuclear translocation is inducible by cAMP. C-terminus deletion abolishes PATZ1 interaction with RIα and results in its localization in the nucleus. PATZ1 transactivates the cMyc promoter and the presence of cAMP and co-expression with RIα modulates its transactivation. Moreover, PATZ1 is aberrantly expressed in cancer. Taken together, our results showed a potentially novel mechanism of cAMP signaling mediated through the interaction of RIα with PATZ1 that is independent of the kinase activity of PKA, and the aberrant expression of PATZ1 in cancer point to its role in cell growth regulation.

  13. Interaction of the regulatory subunit of the cAMP-dependent protein kinase with PATZ1 (ZNF278)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weng-Lang [Long Island Jewish Medical Center, North Shore University Hospital, Manhasset, NY 11030 (United States); Ravatn, Roald [Department of Medicine, University of Toledo, College of Medicine, Toledo, OH 43614 (United States); Kudoh, Kazuya [Department of Medicine, University of Toledo, College of Medicine, Toledo, OH 43614 (United States); Department of Obstetrics and Gynecology, National Defense Medical College, Tokorozawa, Saitama (Japan); Alabanza, Leah [Department of Medicine, University of Toledo, College of Medicine, Toledo, OH 43614 (United States); Chin, Khew-Voon, E-mail: khew-voon.chin@utoledo.edu [Department of Medicine, University of Toledo, College of Medicine, Toledo, OH 43614 (United States)

    2010-01-15

    The effects of cAMP in cell are predominantly mediated by the cAMP-dependent protein kinase (PKA), which is composed of two genetically distinct subunits, catalytic (C) and regulatory (R), forming a tetrameric holoenzyme R{sub 2}C{sub 2}. The only known function for the R subunit is that of inhibiting the activity of the C subunit kinase. It has been shown that overexpression of RI{alpha}, but not the C subunit kinase, is associated with neoplastic transformation. In addition, it has also been demonstrated that mutation in the RI{alpha}, but not the C subunit is associated with increased resistance to the DNA-damaging anticancer drug cisplatin, thus suggesting that the RI{alpha} subunit of PKA may have functions independent of the kinase. We show here that the RI{alpha} subunit interacts with a BTB/POZ domain zinc-finger transcription factor, PATZ1 (ZNF278), and co-expression with RI{alpha} results in its sequestration in the cytoplasm. The cytoplasmic/nuclear translocation is inducible by cAMP. C-terminus deletion abolishes PATZ1 interaction with RI{alpha} and results in its localization in the nucleus. PATZ1 transactivates the cMyc promoter and the presence of cAMP and co-expression with RI{alpha} modulates its transactivation. Moreover, PATZ1 is aberrantly expressed in cancer. Taken together, our results showed a potentially novel mechanism of cAMP signaling mediated through the interaction of RI{alpha} with PATZ1 that is independent of the kinase activity of PKA, and the aberrant expression of PATZ1 in cancer point to its role in cell growth regulation.

  14. Differential Roles of the Glycogen-Binding Domains of β Subunits in Regulation of the Snf1 Kinase Complex▿

    Science.gov (United States)

    Mangat, Simmanjeet; Chandrashekarappa, Dakshayini; McCartney, Rhonda R.; Elbing, Karin; Schmidt, Martin C.

    2010-01-01

    Members of the AMP-activated protein kinase family, including the Snf1 kinase of Saccharomyces cerevisiae, are activated under conditions of nutrient stress. AMP-activated protein kinases are heterotrimeric complexes composed of a catalytic α subunit and regulatory β and γ subunits. In this study, the role of the β subunits in the regulation of Snf1 activity was examined. Yeasts express three isoforms of the AMP-activated protein kinase consisting of Snf1 (α), Snf4 (γ), and one of three alternative β subunits, either Sip1, Sip2, or Gal83. The Gal83 isoform of the Snf1 complex is the most abundant and was analyzed in the greatest detail. All three β subunits contain a conserved domain referred to as the glycogen-binding domain. The deletion of this domain from Gal83 results in a deregulation of the Snf1 kinase, as judged by a constitutive activity independent of glucose availability. In contrast, the deletion of this homologous domain from the Sip1 and Sip2 subunits had little effect on Snf1 kinase regulation. Therefore, the different Snf1 kinase isoforms are regulated through distinct mechanisms, which may contribute to their specialized roles in different stress response pathways. In addition, the β subunits are subjected to phosphorylation. The responsible kinases were identified as being Snf1 and casein kinase II. The significance of the phosphorylation is unclear since the deletion of the region containing the phosphorylation sites in Gal83 had little effect on the regulation of Snf1 in response to glucose limitation. PMID:19897735

  15. Differential roles of the glycogen-binding domains of beta subunits in regulation of the Snf1 kinase complex.

    Science.gov (United States)

    Mangat, Simmanjeet; Chandrashekarappa, Dakshayini; McCartney, Rhonda R; Elbing, Karin; Schmidt, Martin C

    2010-01-01

    Members of the AMP-activated protein kinase family, including the Snf1 kinase of Saccharomyces cerevisiae, are activated under conditions of nutrient stress. AMP-activated protein kinases are heterotrimeric complexes composed of a catalytic alpha subunit and regulatory beta and gamma subunits. In this study, the role of the beta subunits in the regulation of Snf1 activity was examined. Yeasts express three isoforms of the AMP-activated protein kinase consisting of Snf1 (alpha), Snf4 (gamma), and one of three alternative beta subunits, either Sip1, Sip2, or Gal83. The Gal83 isoform of the Snf1 complex is the most abundant and was analyzed in the greatest detail. All three beta subunits contain a conserved domain referred to as the glycogen-binding domain. The deletion of this domain from Gal83 results in a deregulation of the Snf1 kinase, as judged by a constitutive activity independent of glucose availability. In contrast, the deletion of this homologous domain from the Sip1 and Sip2 subunits had little effect on Snf1 kinase regulation. Therefore, the different Snf1 kinase isoforms are regulated through distinct mechanisms, which may contribute to their specialized roles in different stress response pathways. In addition, the beta subunits are subjected to phosphorylation. The responsible kinases were identified as being Snf1 and casein kinase II. The significance of the phosphorylation is unclear since the deletion of the region containing the phosphorylation sites in Gal83 had little effect on the regulation of Snf1 in response to glucose limitation.

  16. Dynamic inter-subunit interactions in thermophilic F1-ATPase subcomplexes studied by cross-correlated relaxation-enhanced polarization transfer NMR

    International Nuclear Information System (INIS)

    Kobayashi, Masumi; Yagi, Hiromasa; Yamazaki, Toshio; Yoshida, Masasuke; Akutsu, Hideo

    2008-01-01

    F 1 -ATPase is a unique enzyme in terms of its rotational catalytic activity. The smallest unit showing this property is the α 3 β 3 γ complex (351 kDa). For investigation of such a huge system by means of solution NMR, we have explored a suitable NMR method using F 1 -ATPase subcomplexes from a thermophilic Bacillus PS3 including an α 3 β 3 hexamer (319 kDa). Pulse sequences for large molecules, effects of deuteration and simplification of the spectra were examined in this work. Since the β subunit includes the catalytic site, this was the target of the analysis in this work. The combination of [ 15 N, 1 H]-CRINEPT-HMQC-[ 1 H]-TROSY, deuteration of both α and β subunits, and segmental isotope-labeling was found essential to analyze such a huge and complex molecular system. Utilizing this method, subcomplexes composed of α and β subunits were investigated in terms of inter-subunit interactions. It turned out that there is equilibrium among monomers, heterodimers and the α 3 β 3 hexamers in solution. The rate of exchange between the dimer and hexamer is in the slow regime on the NMR time scale. In chemical shift perturbation experiments, the N-terminal domain was found to be involved in strong inter-subunit interactions. In contrast, the C-terminal domain was found to be mobile even in the hexamer

  17. Casein kinase 2 down-regulation and activation by polybasic peptides are mediated by acidic residues in the 55-64 region of the beta-subunit. A study with calmodulin as phosphorylatable substrate

    DEFF Research Database (Denmark)

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

    1994-01-01

    to substitute for wild-type beta-subunit as a suppressor of activity toward calmodulin. The only mutations that reduced the ability of the beta-subunit to suppress calmodulin phosphorylation activity, though being compatible with normal reconstitution of CK2 holoenzyme, were those affecting Asp55, Glu57...... are conversely ineffective. The latent "calmodulin kinase" activity of CK2 can also be specifically unmasked by a peptide (alpha[66-86]) reproducing a basic insert of the catalytic subunit. This effect is reversed by equimolar addition of a peptide (beta[55-71]) including the 55-64 acidic stretch of the beta......-subunit. Comparable polylysine stimulation was observed with the holoenzymes reconstituted with either beta wt or the beta mutants capable of assembling with the alpha-subunit, with the notable exception of those bearing Ala substitutions for acidic residues at positions 55, 57, and 59-61. These were nearly...

  18. Immunochemical aspects of crotoxim and its subunits

    International Nuclear Information System (INIS)

    Nakazone, A.K.

    1979-01-01

    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 125 I 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 131 I 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 [pt

  19. Localization in the Nucleolus and Coiled Bodies of Protein Subunits of the Ribonucleoprotein Ribonuclease P

    Science.gov (United States)

    Jarrous, Nayef; Wolenski, Joseph S.; Wesolowski, Donna; Lee, Christopher; Altman, Sidney

    1999-01-01

    The precise location of the tRNA processing ribonucleoprotein ribonuclease P (RNase P) and the mechanism of its intranuclear distribution have not been completely delineated. We show that three protein subunits of human RNase P (Rpp), Rpp14, Rpp29 and Rpp38, are found in the nucleolus and that each can localize a reporter protein to nucleoli of cells in tissue culture. In contrast to Rpp38, which is uniformly distributed in nucleoli, Rpp14 and Rpp29 are confined to the dense fibrillar component. Rpp29 and Rpp38 possess functional, yet distinct domains required for subnucleolar localization. The subunit Rpp14 lacks such a domain and appears to be dependent on a piggyback process to reach the nucleolus. Biochemical analysis suggests that catalytically active RNase P exists in the nucleolus. We also provide evidence that Rpp29 and Rpp38 reside in coiled bodies, organelles that are implicated in the biogenesis of several other small nuclear ribonucleoproteins required for processing of precursor mRNA. Because some protein subunits of RNase P are shared by the ribosomal RNA processing ribonucleoprotein RNase MRP, these two evolutionary related holoenzymes may share common intranuclear localization and assembly pathways to coordinate the processing of tRNA and rRNA precursors. PMID:10444065

  20. Catalytic bioreactors and methods of using same

    Science.gov (United States)

    Worden, Robert Mark; Liu, Yangmu Chloe

    2017-07-25

    Various embodiments provide a bioreactor for producing a bioproduct comprising one or more catalytically active zones located in a housing and adapted to keep two incompatible gaseous reactants separated when in a gas phase, wherein each of the one or more catalytically active zones may comprise a catalytic component retainer and a catalytic component retained within and/or thereon. Each of the catalytically active zones may additionally or alternatively comprise a liquid medium located on either side of the catalytic component retainer. Catalytic component may include a microbial cell culture located within and/or on the catalytic component retainer, a suspended catalytic component suspended in the liquid medium, or a combination thereof. Methods of using various embodiments of the bioreactor to produce a bioproduct, such as isobutanol, are also provided.

  1. 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....

  2. Involvement of proteasomal subunits zeta and iota in RNA degradation.

    Science.gov (United States)

    Petit, F; Jarrousse, A S; Dahlmann, B; Sobek, A; Hendil, K B; Buri, J; Briand, Y; Schmid, H P

    1997-01-01

    We have identified two distinct subunits of 20 S proteasomes that are associated with RNase activity. Proteasome subunits zeta and iota, eluted from two-dimensional Western blots, hydrolysed tobacco mosaic virus RNA, whereas none of the other subunits degraded this substrate under the same conditions. Additionally, proteasomes were dissociated by 6 M urea, and subunit zeta, containing the highest RNase activity, was isolated by anion-exchange chromatography and gel filtration. Purified subunit zeta migrated as a single spot on two-dimensional PAGE with a molecular mass of approx. 28 kDa. Addition of anti-(subunit zeta) antibodies led to the co-precipitation of this proteasome subunit and nuclease activity. This is the first evidence that proteasomal alpha-type subunits are associated with an enzymic activity, and our results provide further evidence that proteasomes may be involved in cellular RNA metabolism. PMID:9337855

  3. Identification of the gamma subunit-interacting residues on photoreceptor cGMP phosphodiesterase, PDE6alpha '.

    Science.gov (United States)

    Granovsky, A E; Artemyev, N O

    2000-12-29

    Photoreceptor cGMP phosphodiesterase (PDE6) is the effector enzyme in the G protein-mediated visual transduction cascade. In the dark, the activity of PDE6 is shut off by the inhibitory gamma subunit (Pgamma). Chimeric proteins between cone PDE6alpha' and cGMP-binding and cGMP-specific PDE (PDE5) have been constructed and expressed in Sf9 cells to study the mechanism of inhibition of PDE6 catalytic activity by Pgamma. Substitution of the segment PDE5-(773-820) by the corresponding PDE6alpha'-(737-784) sequence in the wild-type PDE5 or in a PDE5/PDE6alpha' chimera containing the catalytic domain of PDE5 results in chimeric enzymes capable of inhibitory interaction with Pgamma. The catalytic properties of the chimeric PDEs remained similar to those of PDE5. Ala-scanning mutational analysis of the Pgamma-binding region, PDE6alpha'-(750-760), revealed PDE6alpha' residues essential for the interaction. The M758A mutation markedly impaired and the Q752A mutation moderately impaired the inhibition of chimeric PDE by Pgamma. The analysis of the catalytic properties of mutant PDEs and a model of the PDE6 catalytic domain suggest that residues Met(758) and Gln(752) directly bind Pgamma. A model of the PDE6 catalytic site shows that PDE6alpha'-(750-760) forms a loop at the entrance to the cGMP-binding pocket. Binding of Pgamma to Met(758) would effectively block access of cGMP to the catalytic cavity, providing a structural basis for the mechanism of PDE6 inhibition.

  4. 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

  5. Catalytic properties of niobium compounds

    International Nuclear Information System (INIS)

    Tanabe, K.; Iizuka, T.

    1983-04-01

    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) [pt

  6. Catalytic Decoupling of Quantum Information

    DEFF Research Database (Denmark)

    Majenz, Christian; Berta, Mario; Dupuis, Frédéric

    2017-01-01

    The decoupling technique is a fundamental tool in quantum information theory with applications ranging from quantum thermodynamics to quantum many body physics to the study of black hole radiation. In this work we introduce the notion of catalytic decoupling, that is, decoupling in the presence...... and quantum state merging, and leads to a resource theory of decoupling....

  7. Synthesis, spectroscopic characterization and catalytic oxidation ...

    Indian Academy of Sciences (India)

    were characterized by infrared, electronic, electron paramagnetic resonance ... The catalytic oxidation property of ruthenium(III) complexes were also ... cies at room temperature. ..... aldehyde part of Schiff base ligands, catalytic activ- ity of new ...

  8. Muscular subunits transplantation for facial reanimation

    Directory of Open Access Journals (Sweden)

    Hazan André Salo Buslik

    2006-01-01

    Full Text Available PURPOSE: To present an alternative technique for reconstruction of musculocutaneous damages in the face transferring innervated subsegments(subunits of the latissimus dorsi flap for replacement of various facial mimetic muscles. METHODS: One clinical case of trauma with skin and mimetic muscles damage is described as an example of the technique. The treatment was performed with microsurgical transfer of latissimus dorsi muscle subunits. Each subunit present shape and dimensions of the respective mimetic muscles replaced. The origin, insertions and force vectors for the mimicmuscle lost were considered. Each subsegment has its own arterial and venous supply with a motor nerve component for the muscular unit. RESULTS: Pre and one year postoperative photos registration of static and dynamic mimic aspects, as well as digital electromyography digital data of the patients were compared. The transplanted muscular units presented myoeletric activity, fulfilling both the functional and cosmetic aspect. CONCLUSION: This technique seems to be a promising way to deal with the complex musculocutaneous losses of the face as well as facial palsy.

  9. Influvac, a trivalent inactivated subunit influenza vaccine.

    Science.gov (United States)

    Zuccotti, Gian Vincenzo; Fabiano, Valentina

    2011-01-01

    Influenza represents a major sanitary and socio-economic burden and vaccination is universally considered the most effective strategy for preventing the disease and its complications. Traditional influenza vaccines have been on the market since the late 1940s, with million of doses administered annually worldwide, and demonstrated a substantial efficacy and safety. The trivalent inactivated subunit vaccine has been available for more than 25 years and has been studied in healthy children, adults and the elderly and in people affected by underlying chronic medical conditions. We describe vaccine technology focusing on subunit vaccine production procedures and mode of action and provide updated information on efficacy and safety available data. A review of efficacy and safety data in healthy subjects and in high risk populations from major sponsor- and investigator-driven studies. The vaccine showed a good immunogenicity and a favorable safety profile in all target groups. In the panorama of actually available influenza vaccines, trivalent inactivated subunit vaccine represents a well-established tool for preventing flu and the associated complications.

  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. Soybean glycinin subunits: Characterization of physicochemical and adhesion properties.

    Science.gov (United States)

    Mo, Xiaoqun; Zhong, Zhikai; Wang, Donghai; Sun, Xiuzhi

    2006-10-04

    Soybean proteins have shown great potential for applications as renewable and environmentally friendly adhesives. The objective of this work was to study physicochemical and adhesion properties of soy glycinin subunits. Soybean glycinin was extracted from soybean flour and then fractionated into acidic and basic subunits with an estimated purity of 90 and 85%, respectively. Amino acid composition of glycinin subunits was determined. The high hydrophobic amino acid content is a major contributor to the solubility behavior and water resistance of the basic subunits. Acidic subunits and glycinin had similar solubility profiles, showing more than 80% solubility at pH 2.0-4.0 or 6.5-12.0, whereas basic subunits had considerably lower solubility with the minimum at pH 4.5-8.0. Thermal analysis using a differential scanning calorimeter suggested that basic subunits form new oligomeric structures with higher thermal stability than glycinin but no highly ordered structures present in isolated acidic subunits. The wet strength of basic subunits was 160% more than that of acidic subunits prepared at their respective isoelectric points (pI) and cured at 130 degrees C. Both pH and the curing temperature significantly affected adhesive performance. High-adhesion water resistance was usually observed for adhesives from protein prepared at their pI values and cured at elevated temperatures. Basic subunits are responsible for the water resistance of glycinin and are a good starting material for the development of water-resistant adhesives.

  12. Shared active site architecture between archaeal PolD and multi-subunit RNA polymerases revealed by X-ray crystallography.

    Science.gov (United States)

    Sauguet, Ludovic; Raia, Pierre; Henneke, Ghislaine; Delarue, Marc

    2016-08-22

    Archaeal replicative DNA polymerase D (PolD) constitute an atypical class of DNA polymerases made of a proofreading exonuclease subunit (DP1) and a larger polymerase catalytic subunit (DP2), both with unknown structures. We have determined the crystal structures of Pyrococcus abyssi DP1 and DP2 at 2.5 and 2.2 Å resolution, respectively, revealing a catalytic core strikingly different from all other known DNA polymerases (DNAPs). Rather, the PolD DP2 catalytic core has the same 'double-psi β-barrel' architecture seen in the RNA polymerase (RNAP) superfamily, which includes multi-subunit transcriptases of all domains of life, homodimeric RNA-silencing pathway RNAPs and atypical viral RNAPs. This finding bridges together, in non-viral world, DNA transcription and DNA replication within the same protein superfamily. This study documents further the complex evolutionary history of the DNA replication apparatus in different domains of life and proposes a classification of all extant DNAPs.

  13. Catalytic process for tritium exchange reaction

    International Nuclear Information System (INIS)

    Hansoo Lee; Kang, H.S.; Paek, S.W.; Hongsuk Chung; Yang Geun Chung; Sook Kyung Lee

    2001-01-01

    The catalytic activities for a hydrogen isotope exchange were measured through the reaction of a vapor and gas mixture. The catalytic activity showed to be comparable with the published data. Since the gas velocity is relatively low, the deactivation was not found clearly during the 5-hour experiment. Hydrogen isotope transfer experiments were also conducted through the liquid phase catalytic exchange reaction column that consisted of a catalytic bed and a hydrophilic bed. The efficiencies of both the catalytic and hydrophilic beds were higher than 0.9, implying that the column performance was excellent. (author)

  14. Origem e relação do trabalho com o ser humano e as limitações do trabalho na prisão = Origin and work relationship with human being and labor limitations in prison

    Directory of Open Access Journals (Sweden)

    Correa, Marina Aparecida Pimenta da Cruz

    2016-01-01

    Full Text Available O presente trabalho se propõe a analisar a origem e a relação do trabalho com o homem, elucidando a realização do trabalho prisional e os entraves para seu funcionamento, a fim de conciliar as diretrizes da Lei de Execução Penal que estabelece o trabalho como forma de (re socialização na prisão à realidade apresentada àqueles que cumprem pena restritiva de liberdade. Considerando a categoria trabalho como determinante na vida humana ao longo da história, relegando status de homem trabalhador valorizado pela sociedade, a identidade profissional acaba, muitas vezes, confundida com o próprio indivíduo no meio social. Portanto, torna-se necessário pensar no lugar que o trabalho ocupa na vida do homem, sobretudo de pessoas que passaram pelo sistema prisional, uma vez que a identidade do sujeito se atrela, geralmente, ao trabalho que exerce no meio social

  15. 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.

  16. 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.

  17. Catalytic processes for cleaner fuels

    International Nuclear Information System (INIS)

    Catani, R.; Marchionna, M.; Rossini, S.

    1999-01-01

    More stringent limitations on vehicle emissions require different measurement: fuel reformulation is one of the most important and is calling for a noticeable impact on refinery assets. Composition rangers of the future fuels have been defined on a time scale. In this scenario the evolution of catalytic technologies becomes a fundamental tool for allowing refinery to reach the fixed-by-law targets. In this paper, the refinery process options to meet each specific requirements of reformulated fuels are surveyed [it

  18. Human aldolase B subunit-specific radioimmunoassay

    International Nuclear Information System (INIS)

    Asaka, M.; Alpert, E.

    1983-01-01

    A radioimmunoassay was developed for the direct quantification of aldolase B in human serum and tissues. The method is a double-antibody radioimmunoassay technique using radioiodinated aldolase B homopolymer as ligand, chicken antibodies to aldolase B and rabbit antibodies to chicken IgG. This radioimmunoassay was shown to be specific for the aldolase B subunit, with no cross-reactivity with either human aldolase A subunit or homopolymeric human aldolase C (C 4 ). The lowest measurable amount by this method was 2 ng/ml. Aldolase B is predominantly found in normal liver tissue, with relatively-high aldolase B levels also observed in kidney. Aldolase B levels in the serum obtained from 11 normal subjects ranged from 23 to 38 ng/ml, with a mean of 28.5 +- 9.2 (S.D.) ng/ml. Almost all of patients with hepatitis had serum aldolase B levels greater than 30 ng/ml. In cancer patients, serum aldolase B was slightly elevated in patients with metastatic liver cancer and primary lever cell carcinoma, whereas no elevation of serum aldolase B was shown in patients without liver metastasis. (Auth.)

  19. Subunit stoichiometry of the chloroplast photosystem I complex

    International Nuclear Information System (INIS)

    Bruce, B.D.; Malkin, R.

    1988-01-01

    A native photosystem I (PS I) complex and a PS I core complex depleted of antenna subunits has been isolated from the uniformly 14 C-labeled aquatic higher plant, Lemna. These complexes have been analyzed for their subunit stoichiometry by quantitative sodium dodecyl sulfate-polyacrylamide gel electrophoresis methods. The results for both preparations indicate that one copy of each high molecular mass subunit is present per PS I complex and that a single copy of most low molecular mass subunits is also present. These results suggest that iron-sulfur center X, an early PS I electron acceptor proposed to bind to the high molecular mass subunits, contains a single [4Fe-4S] cluster which is bound to a dimeric structure of high molecular mass subunits, each providing 2 cysteine residues to coordinate this cluster

  20. CMG helicase and DNA polymerase ε form a functional 15-subunit holoenzyme for eukaryotic leading-strand DNA replication.

    Science.gov (United States)

    Langston, Lance D; Zhang, Dan; Yurieva, Olga; Georgescu, Roxana E; Finkelstein, Jeff; Yao, Nina Y; Indiani, Chiara; O'Donnell, Mike E

    2014-10-28

    DNA replication in eukaryotes is asymmetric, with separate DNA polymerases (Pol) dedicated to bulk synthesis of the leading and lagging strands. Pol α/primase initiates primers on both strands that are extended by Pol ε on the leading strand and by Pol δ on the lagging strand. The CMG (Cdc45-MCM-GINS) helicase surrounds the leading strand and is proposed to recruit Pol ε for leading-strand synthesis, but to date a direct interaction between CMG and Pol ε has not been demonstrated. While purifying CMG helicase overexpressed in yeast, we detected a functional complex between CMG and native Pol ε. Using pure CMG and Pol ε, we reconstituted a stable 15-subunit CMG-Pol ε complex and showed that it is a functional polymerase-helicase on a model replication fork in vitro. On its own, the Pol2 catalytic subunit of Pol ε is inefficient in CMG-dependent replication, but addition of the Dpb2 protein subunit of Pol ε, known to bind the Psf1 protein subunit of CMG, allows stable synthesis with CMG. Dpb2 does not affect Pol δ function with CMG, and thus we propose that the connection between Dpb2 and CMG helps to stabilize Pol ε on the leading strand as part of a 15-subunit leading-strand holoenzyme we refer to as CMGE. Direct binding between Pol ε and CMG provides an explanation for specific targeting of Pol ε to the leading strand and provides clear mechanistic evidence for how strand asymmetry is maintained in eukaryotes.

  1. 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.

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

    International Nuclear Information System (INIS)

    Barbieri, J.T.; Mende-Mueller, L.M.; Rappuoli, R.; Collier, R.J.

    1989-01-01

    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

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

    International Nuclear Information System (INIS)

    Polekhina, Galina; Feil, Susanne C.; Gupta, Abhilasha; O’Donnell, Paul; Stapleton, David; Parker, Michael W.

    2004-01-01

    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

  5. 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

  6. Catalytic Organometallic Reactions of Ammonia

    Science.gov (United States)

    Klinkenberg, Jessica L.

    2012-01-01

    Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

  7. Catalytic cracking of hydrocarbon oils

    Energy Technology Data Exchange (ETDEWEB)

    1940-09-12

    A process is described for the vapor phase catalytic cracking of hydrocarbon oils boiling substantially in the gas oil range. The reaction takes place in the presence of a solid catalyst between 700 to 900/sup 0/F under pressure between atmospheric and 400 psi. A gas containing between 20 and 90 mol % of free hydrogen is used. The reaction is allowed to proceed until consumption of the free begins. The reaction is discontinued at that point and the catalyst is regenerated for further use.

  8. 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.

  9. Catalytic enantioselective Reformatsky reaction with ketones

    NARCIS (Netherlands)

    Fernandez-Ibanez, M. Angeles; Macia, Beatriz; Minnaard, Adriaan J.; Feringa, Ben L.

    2008-01-01

    Chiral tertiary alcohols were obtained with good yields and enantioselectivities via a catalytic Reformatsky reaction with ketones, including the challenging diaryl ketones, using chiral BINOL derivatives.

  10. Petrochemical promoters in catalytic cracking

    International Nuclear Information System (INIS)

    Gomez, Maria; Vargas, Clemencia; Lizcano, Javier

    2010-01-01

    This study is based on the current scheme followed by a refinery with available Catalytic Cracking capacity to process new feedstocks such as Straight Run Naphtha and Naphthas from FCC. These feedstocks are of petrochemical interest to produce Ethane, Ethylene, Propylene, i-Butane, Toluene and Xylene. To evaluate the potential of these new streams versus the Cracking-charged Residues, it was performed a detailed chemical analysis on the structural groups in carbons [C1-C12] at the reactor product obtained in pilot plant. A catalyst with and without Propylene Promoter Additive was used. This study analyzes the differences in the chemical composition of the feedstocks, relating them to the yield of each petrochemical product. Straight Run Naphthas with a high content of Naphthenes, and Paraffines n[C5-C12] and i[C7-C12] are selective to the production of i-Butane and Propane, while Naphthas from FCC with a high content of n[C5-C12]Olefins, i-Olefins, and Aromatics are more selective to Propylene, Toluene, and Xylene. Concerning Catalytic Cracking of Naphthas, the Additive has similar selectivity for all the petrochemical products, their yields increase by about one point with 4%wt of Additive, while in cracking of Residues, the Additive increases in three points Propylene yield, corresponding to a selectivity of 50% (?C3= / ?LPG).

  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. Catalytic converters in the fireplace

    International Nuclear Information System (INIS)

    Kouki, J.

    1995-01-01

    In addition to selecting the appropriate means of heating and using dry fuel, the amount of harmful emissions contained by flue gases produced by fireplaces can be reduced by technical means. One such option is to use an oxidising catalytic converter. Tests at TTS Institute's Heating Studies Experimental Station have focused on two such converters (dense and coarse) mounted in light-weight iron heating stoves. The ability of the dense catalytic converter to oxidise carbon monoxide gases proved to be good. The concentration of carbon monoxide in the flue gases was reduced by as much as 90 %. Measurements conducted by VTT (Technical Research Centre of Finland) showed that the conversion of other gases, e.g. of methane, was good. The exhaust resistance caused by the dense converter was so great as to necessitate the mounting of a fluegas evacuation fan in the chimney for the purpose of creating sufficient draught. When relying on natural draught, the dense converter requires a chimney of at least 7 metres and a by-pass connection while the fire is being lit. In addition, the converter will have to be constructed to be less dense and this will mean that it's capability to oxidise non-combusted gases will be reduced. The coarse converter did not impair the draught but it's oxidising property was insufficient. With the tests over, the converter was not observed to have become blocked up by impurities

  13. 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......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...... of immunostimulators and antigens, respectively, into liposomes, and the choice of immunostimulator should ideally be based on knowledge regarding the specific PRR expression profile of the target APCs. Here, we review state-of-the-art formulation approaches employed for the inclusion of immunostimulators and subunit...

  14. 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

  15. Myristoylated α subunits of guanine nucleotide-binding regulatory proteins

    International Nuclear Information System (INIS)

    Buss, J.E.; Mumby, S.M.; Casey, P.J.; Gilman, A.G.; Sefton, B.M.

    1987-01-01

    Antisera directed against specific subunits of guanine nucleotide-binding regulatory proteins (G proteins) were used to immunoprecipitate these polypeptides from metabolically labeled cells. This technique detects, in extracts of a human astrocytoma cell line, the α subunits of G/sub s/ (stimulatory) (α 45 and α 52 ), a 41-kDa subunit of G/sub i/ (inhibitory) (α 41 ), a 40-kDa protein (α 40 ), and the 36-kDa β subunit. No protein that comigrated with the α subunit of G 0 (unknown function) (α 39 ) was detected. In cells grown in the presence of [ 3 H]myristic acid, α 41 and α 40 contained 3 H label, while the β subunit did not. Chemical analysis of lipids attached covalently to purified α 41 and α 39 from bovine brain also revealed myristic acid. Similar analysis of brain G protein β and γ subunits and of G/sub t/ (Transducin) subunits (α, β, and γ) failed to reveal fatty acids. The fatty acid associated with α 41 , α 40 , and α 39 was stable to treatment with base, suggesting that the lipid is linked to the polypeptide via an amide bond. These GTP binding proteins are thus identified as members of a select group of proteins that contains myristic acid covalently attached to the peptide backbone. Myristate may play an important role in stabilizing interactions of G proteins with phospholipid or with membrane-bound proteins

  16. Development of a Subunit Vaccine for Contagious Bovine ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Their work has set the stage for commercial development of a sub-unit vaccine. ... The sub-unit vaccine will be cost-effective, easy to produce, and safe. How it will make a ... IDRC invites applications for the IDRC Doctoral Research Awards.

  17. Studies on the subunits of human glycoprotein hormones in relation to reproduction

    International Nuclear Information System (INIS)

    Hagen, C.

    1977-01-01

    In this review summarising present knowledge of the biological and immunological activity of the subunits of human glycoprotein hormones, the specificity of the α-subunit and β-subunit radioimmunoassays are discussed. The crossreaction studies performed with the α-subunit radioimmunoassays are aummarised in one table while those with the β-subunit radioimmunoassays are presented in a second table. (JIW)

  18. INTRINSIC REGULATION OF HEMOGLOBIN EXPRESSION BY VARIABLE SUBUNIT INTERFACE STRENGTHS

    Science.gov (United States)

    Manning, James M.; Popowicz, Anthony M.; Padovan, Julio C.; Chait, Brian T.; Manning, Lois R.

    2012-01-01

    SUMMARY The expression of the six types of human hemoglobin subunits over time is currently considered to be regulated mainly by transcription factors that bind to upstream control regions of the gene (the “extrinsic” component of regulation). Here we describe how subunit pairing and further assembly to tetramers in the liganded state is influenced by the affinity of subunits for one another (the “intrinsic” component of regulation). The adult hemoglobin dimers have the strongest subunit interfaces and the embryonic hemoglobins are the weakest with fetal hemoglobins of intermediate strength, corresponding to the temporal order of their expression. These variable subunit binding strengths and the attenuating effects of acetylation contribute to the differences with which these hemoglobin types form functional O2-binding tetramers consistent with gene switching. PMID:22129306

  19. Heterogeneous catalytic degradation of polyacrylamide solution | Hu ...

    African Journals Online (AJOL)

    Modified with trace metal elements, the catalytic activity of Fe2O3/Al2O3 could be changed greatly. Among various trace metal elements, Fe2O3/Al2O3 catalysts modified with Co and Cu showed great increase on catalytic activity. International Journal of Engineering, Science and Technology, Vol. 2, No. 7, 2010, pp. 110- ...

  20. Method of fabricating a catalytic structure

    Science.gov (United States)

    Rollins, Harry W [Idaho Falls, ID; Petkovic, Lucia M [Idaho Falls, ID; Ginosar, Daniel M [Idaho Falls, ID

    2009-09-22

    A precursor to a catalytic structure comprising zinc oxide and copper oxide. The zinc oxide has a sheet-like morphology or a spherical morphology and the copper oxide comprises particles of copper oxide. The copper oxide is reduced to copper, producing the catalytic structure. The catalytic structure is fabricated by a hydrothermal process. A reaction mixture comprising a zinc salt, a copper salt, a hydroxyl ion source, and a structure-directing agent is formed. The reaction mixture is heated under confined volume conditions to produce the precursor. The copper oxide in the precursor is reduced to copper. A method of hydrogenating a carbon oxide using the catalytic structure is also disclosed, as is a system that includes the catalytic structure.

  1. Catalytic hydrogenation of carbon monoxide

    International Nuclear Information System (INIS)

    Wayland, B.B.

    1993-12-01

    Focus of this project is on developing new approaches for hydrogenation of carbon monoxide to produce organic oxygenates at mild conditions. The strategies to accomplish CO reduction are based on favorable thermodynamics manifested by rhodium macrocycles for producing a series of intermediates implicated in the catalytic hydrogenation of CO. Metalloformyl complexes from reactions of H 2 and CO, and CO reductive coupling to form metallo α-diketone species provide alternate routes to organic oxygenates that utilize these species as intermediates. Thermodynamic and kinetic-mechanistic studies are used in guiding the design of new metallospecies to improve the thermodynamic and kinetic factors for individual steps in the overall process. 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. Non-macrocyclic ligand complexes that emulate the favorable thermodynamic features associated with rhodium macrocycles, but that also manifest improved reaction kinetics are promising candidates for future development

  2. Selective catalytic oxidation of ammonia

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

    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. Non-catalytic recuperative reformer

    Science.gov (United States)

    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.

  4. Studies of Catalytic Model Systems

    DEFF Research Database (Denmark)

    Holse, Christian

    The overall topic of this thesis is within the field of catalysis, were model systems of different complexity have been studied utilizing a multipurpose Ultra High Vacuum chamber (UHV). The thesis falls in two different parts. First a simple model system in the form of a ruthenium single crystal...... of the Cu/ZnO nanoparticles is highly relevant to industrial methanol synthesis for which the direct interaction of Cu and ZnO nanocrystals synergistically boost the catalytic activity. The dynamical behavior of the nanoparticles under reducing and oxidizing environments were studied by means of ex situ X......-ray Photoelectron Electron Spectroscopy (XPS) and in situ Transmission Electron Microscopy (TEM). The surface composition of the nanoparticles changes reversibly as the nanoparticles exposed to cycles of high-pressure oxidation and reduction (200 mbar). Furthermore, the presence of metallic Zn is observed by XPS...

  5. 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.)

  6. The evolution of catalytic function

    Science.gov (United States)

    Maurel, Marie-Christine; Ricard, Jacques

    2006-03-01

    It is very likely that the main driving force of enzyme evolution is the requirement to improve catalytic and regulatory efficiency which results from the intrinsic performance as well as from the spatial and functional organization of enzymes in living cells. Kinetic co-operativity may occur in simple monomeric proteins if they display “slow” conformational transitions, at the cost of catalytic efficiency. Oligomeric enzymes on the other hand can be both efficient and co-operative. We speculate that the main reason for the emergence of co-operative oligomeric enzymes is the need for catalysts that are both cooperative and efficient. As it is not useful for an enzyme to respond to a change of substrate concentration in a complex kinetic way, the emergence of symmetry has its probable origin in a requirement for “functional simplicity”. In a living cell, enzyme are associated with other macromolecules and membranes. The fine tuning of their activity may also be reached through mutations of the microenvironment. Our hypothesis is that these mutations are related to the vectorial transport of molecules, to achieve the hysteresis loops of enzyme reactions generated by the coupling of reaction and diffusion, through the co-operativity brought about by electric interactions between a charged substrate and a membrane, and last but not least, through oscillations. As the physical origins of these effects are very simple and do not require complex molecular devices, it is very likely that the functional advantage generated by the spatial and functional organization of enzyme molecules within the cell have appeared in prebiotic catalysis or very early during the primeval stages of biological evolution. We shall began this paper by presenting the nature of the probable earliest catalysts in the RNA world.

  7. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-08

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

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

    International Nuclear Information System (INIS)

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-01-01

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

  10. The light subunit of system bo,+ is fully functional in the absence of the heavy subunit

    OpenAIRE

    Reig, Núria; Chillarón, Josep; Bartoccioni, Paola; Fernández, Esperanza; Bendahan, Annie; Zorzano, Antonio; Kanner, Baruch; Palacín, Manuel; Bertran, Joan

    2002-01-01

    The heteromeric amino acid transporters are composed of a type II glycoprotein and a non-glycosylated polytopic membrane protein. System bo,+ exchanges dibasic for neutral amino acids. It is composed of rBAT and bo,+AT, the latter being the polytopic membrane subunit. Mutations in either of them cause malfunction of the system, leading to cystinuria. bo,+AT-reconstituted systems from HeLa or MDCK cells catalysed transport of arginine that was totally dependent on the presence of one of the bo...

  11. The F1 -ATPase from Trypanosoma brucei is elaborated by three copies of an additional p18-subunit.

    Science.gov (United States)

    Gahura, Ondřej; Šubrtová, Karolína; Váchová, Hana; Panicucci, Brian; Fearnley, Ian M; Harbour, Michael E; Walker, John E; Zíková, Alena

    2018-02-01

    The F-ATPases (also called the F 1 F o -ATPases or ATP synthases) are multi-subunit membrane-bound molecular machines that produce ATP in bacteria and in eukaryotic mitochondria and chloroplasts. The structures and enzymic mechanisms of their F 1 -catalytic domains are highly conserved in all species investigated hitherto. However, there is evidence that the F-ATPases from the group of protozoa known as Euglenozoa have novel features. Therefore, we have isolated pure and active F 1 -ATPase from the euglenozoan parasite, Trypanosoma brucei, and characterized it. All of the usual eukaryotic subunits (α, β, γ, δ, and ε) were present in the enzyme, and, in addition, two unique features were detected. First, each of the three α-subunits in the F 1 -domain has been cleaved by proteolysis in vivo at two sites eight residues apart, producing two assembled fragments. Second, the T. brucei F 1 -ATPase has an additional subunit, called p18, present in three copies per complex. Suppression of expression of p18 affected in vitro growth of both the insect and infectious mammalian forms of T. brucei. It also reduced the levels of monomeric and multimeric F-ATPase complexes and diminished the in vivo hydrolytic activity of the enzyme significantly. These observations imply that p18 plays a role in the assembly of the F 1 domain. These unique features of the F 1 -ATPase extend the list of special characteristics of the F-ATPase from T. brucei, and also, demonstrate that the architecture of the F 1 -ATPase complex is not strictly conserved in eukaryotes. © 2017 Federation of European Biochemical Societies.

  12. Catalytic modification of cellulose and hemicellulose - Sugarefine

    Energy Technology Data Exchange (ETDEWEB)

    Repo, T. [Helsinki Univ. (Finland),Laboratory of Inorganic Chemistry], email: timo.repo@helsinki.fi

    2012-07-01

    The main goal of the project is to develop catalytic methods for the modification of lignocellulose-based saccharides in the biorefineries. The products of these reactions could be used for example as biofuel components, raw materials for the chemical industry, solvents and precursors for biopolymers. The catalyst development aims at creating efficient, selective and green catalytic methods for profitable use in biorefineries. The project is divided in three work packages: In WP1 (Catalytic dehydration of cellulose) the aim is at developing non-toxic, efficient methods for the catalytic dehydration of cellulose the target molecule being here 5-hydroxymethylfurfural (5-HMF). 5-HMF is an interesting platform chemical for the production of fuel additives, solvents and polymers. In WP2 (Catalytic reduction), the objective of the catalytic reduction studies is to produce commercially interesting monofunctional chemicals, such as 1-butanol or 2-methyltetrahydrofuran (2-MeTHF). In WP3 (Catalytic oxidation), the research focuses on developing a green and efficient oxidation method for producing acids. Whereas acetic and formic acids are bulk chemicals, diacids such as glucaric and xylaric acids are valuable specialty chemicals for detergent, polymer and food production.

  13. Cytochrome oxidase assembly does not require catalytically active cytochrome C.

    Science.gov (United States)

    Barrientos, Antoni; Pierre, Danielle; Lee, Johnson; Tzagoloff, Alexander

    2003-03-14

    Cytochrome c oxidase (COX), the terminal enzyme of the mitochondrial respiratory chain, catalyzes the transfer of electrons from reduced cytochrome c to molecular oxygen. COX assembly requires the coming together of nuclear- and mitochondrial-encoded subunits and the assistance of a large number of nuclear gene products acting at different stages of maturation of the enzyme. In Saccharomyces cerevisiae, expression of cytochrome c, encoded by CYC1 and CYC7, is required not only for electron transfer but also for COX assembly through a still unknown mechanism. We have attempted to distinguish between a functional and structural requirement of cytochrome c in COX assembly. A cyc1/cyc7 double null mutant strain was transformed with the cyc1-166 mutant gene (Schweingruber, M. E., Stewart, J. W., and Sherman, F. (1979) J. Biol. Chem. 254, 4132-4143) that expresses stable but catalytically inactive iso-1-cytochrome c. The COX content of the cyc1/cyc7 double mutant strain harboring non-functional iso-1-cytochrome c has been characterized spectrally, functionally, and immunochemically. The results of these studies demonstrate that cytochrome c plays a structural rather than functional role in assembly of cytochrome c oxidase. In addition to its requirement for COX assembly, cytochrome c also affects turnover of the enzyme. Mutants containing wild type apocytochrome c in mitochondria lack COX, suggesting that only the folded and mature protein is able to promote COX assembly.

  14. The nonenzymatic subunit of pseutarin C, a prothrombin activator from eastern brown snake (Pseudonaja textilis) venom, shows structural similarity to mammalian coagulation factor V.

    Science.gov (United States)

    Rao, Veena S; Swarup, Sanjay; Kini, R Manjunatha

    2003-08-15

    Pseutarin C is a group C prothrombin activator from the venom of the eastern brown snake Pseudonaja textilis. It is a multi-subunit protein complex consisting of catalytic and nonenzymatic subunits similar to coagulation factor Xa and factor Va, respectively. Here we describe the complete sequence of the nonenzymatic subunit. Based on the partial amino acid sequence of the nonenzymatic subunit, degenerate primers were designed. Using a "walking" strategy based on sequentially designed primers, we determined the complete cDNA sequence of the nonenzymatic subunit. The cDNA encodes a protein of 1461 amino acid residues, which includes a 30-residue signal peptide, a mature protein of 1430 amino acid residues, and a stop codon. cDNA blot analysis showed a single transcript of approximately 4.6 kb. The deduced amino acid sequence shows approximately 50% identity to mammalian factor V and by homology has a similar domain structure consisting of domains A1-A2-B-A3-C1-C2. Interestingly, the B domain of pseutarin C is shorter than that of mammalian factor V (FV). Although most of the proteolytic activation sites are conserved, 2 of 3 proteolytic sites cleaved by activated protein C are mutated, and thus activated protein C is not able to inactivate this procoagulant toxin. The predicted posttranslational modifications, including disulfide bonds, N-glycosylation, phosphorylation, and sulfation, in pseutarin C are significantly different compared with bovine factor V. Thus, our data demonstrate that the nonenzymatic subunit of group C prothrombin activators is structurally similar to mammalian FV.

  15. Catalytic Wittig and aza-Wittig reactions

    Directory of Open Access Journals (Sweden)

    Zhiqi Lao

    2016-11-01

    Full Text Available This review surveys the literature regarding the development of catalytic versions of the Wittig and aza-Wittig reactions. The first section summarizes how arsenic and tellurium-based catalytic Wittig-type reaction systems were developed first due to the relatively easy reduction of the oxides involved. This is followed by a presentation of the current state of the art regarding phosphine-catalyzed Wittig reactions. The second section covers the field of related catalytic aza-Wittig reactions that are catalyzed by both phosphine oxides and phosphines.

  16. Catalytic models developed through social work

    DEFF Research Database (Denmark)

    Jensen, Mogens

    2015-01-01

    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......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...

  17. Efficient catalytic combustion in integrated micropellistors

    International Nuclear Information System (INIS)

    Bársony, I; Ádám, M; Fürjes, P; Dücső, Cs; Lucklum, R; Hirschfelder, M; Kulinyi, S

    2009-01-01

    This paper analyses two of the key issues of the development of catalytic combustion-type sensors: the selection and production of active catalytic particles on the micropellistor surface as well as the realization of a reliable thermal conduction between heater element and catalytic surface, for the sensing of temperature increase produced by the combustion. The report also demonstrates that chemical sensor product development by a MEMS process is a continuous struggle for elimination of all uncertainties influencing reliability and sensitivity of the final product

  18. Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis.

    Science.gov (United States)

    Prins, Anneke; Orr, Douglas J; Andralojc, P John; Reynolds, Matthew P; Carmo-Silva, Elizabete; Parry, Martin A J

    2016-03-01

    Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis-Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  19. Genetic analysis of the cytoplasmic dynein subunit families.

    Science.gov (United States)

    Pfister, K Kevin; Shah, Paresh R; Hummerich, Holger; Russ, Andreas; Cotton, James; Annuar, Azlina Ahmad; King, Stephen M; Fisher, Elizabeth M C

    2006-01-01

    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.

  20. 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.

  1. Vacuum-insulated catalytic converter

    Science.gov (United States)

    Benson, David K.

    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.

  2. Catalytic hydrotreatment of refinery waste

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    The object of the project is to produce liquid hydrocarbons by the catalytic hydroprocessing of solid refinery wastes (hard pitches) in order to improve the profitability of deep conversion processes and reduce the excess production of heavy fuels. The project was mostly carried out on the ASVAHL demonstration platform site, at Solaize, and hard pitches were produced primarily by deasphalting of atmospheric or vacuum distillation residues. The project includes two experimental phases and an economic evaluation study phase. In phase 1, two granular catalysts were used to transform pitch into standard low sulphur fuel oil: a continuously moving bed, with demetallation and conversion catalyst; a fixed bed, with hydrorefining catalyst. In phase 2 of the project, it was proven that a hydrotreatment process using a finely dispersed catalyst in the feedstock, can, under realistic operating conditions, transform with goods yields hard pitch into distillates that can be refined through standard methods. In phase 3 of the project, it was shown that the economics of such processes are tightly linked to the price differential between white and black oil products, which is expected to increase in the future. Furthermore, the evolution of environmental constraints will impel the use of such methods, thus avoiding the coproduction of polluting solid residues.

  3. Synthesis of chlorophyll b: Localization of chlorophyllide a oxygenase and discovery of a stable radical in the catalytic subunit

    Science.gov (United States)

    Eggink, Laura L; LoBrutto, Russell; Brune, Daniel C; Brusslan, Judy; Yamasato, Akihiro; Tanaka, Ayumi; Hoober, J Kenneth

    2004-01-01

    Background Assembly of stable light-harvesting complexes (LHCs) in the chloroplast of green algae and plants requires synthesis of chlorophyll (Chl) b, a reaction that involves oxygenation of the 7-methyl group of Chl a to a formyl group. This reaction uses molecular oxygen and is catalyzed by chlorophyllide a oxygenase (CAO). The amino acid sequence of CAO predicts mononuclear iron and Rieske iron-sulfur centers in the protein. The mechanism of synthesis of Chl b and localization of this reaction in the chloroplast are essential steps toward understanding LHC assembly. Results Fluorescence of a CAO-GFP fusion protein, transiently expressed in young pea leaves, was found at the periphery of mature chloroplasts and on thylakoid membranes by confocal fluorescence microscopy. However, when membranes from partially degreened cells of Chlamydomonas reinhardtii cw15 were resolved on sucrose gradients, full-length CAO was detected by immunoblot analysis only on the chloroplast envelope inner membrane. The electron paramagnetic resonance spectrum of CAO included a resonance at g = 4.3, assigned to the predicted mononuclear iron center. Instead of a spectrum of the predicted Rieske iron-sulfur center, a nearly symmetrical, approximately 100 Gauss peak-to-trough signal was observed at g = 2.057, with a sensitivity to temperature characteristic of an iron-sulfur center. A remarkably stable radical in the protein was revealed by an isotropic, 9 Gauss peak-to-trough signal at g = 2.0042. Fragmentation of the protein after incorporation of 125I- identified a conserved tyrosine residue (Tyr-422 in Chlamydomonas and Tyr-518 in Arabidopsis) as the radical species. The radical was quenched by chlorophyll a, an indication that it may be involved in the enzymatic reaction. Conclusion CAO was found on the chloroplast envelope and thylakoid membranes in mature chloroplasts but only on the envelope inner membrane in dark-grown C. reinhardtii cells. Such localization provides further support for the envelope membranes as the initial site of Chl b synthesis and assembly of LHCs during chloroplast development. Identification of a tyrosine radical in the protein provides insight into the mechanism of Chl b synthesis. PMID:15086960

  4. 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.

  5. Low LET radiation-induced telomerase catalytic subunit promoter activation is mediated by nuclear factor Kappa B

    International Nuclear Information System (INIS)

    Natarajan, M.; Hong, F.A.; Mohan, S.; Herman, T.S.

    2003-01-01

    Full text: The objective of this study is to understand whether low doses of low LET radiation induces survival advantage in normal cells. As an increase in telomerase activity is associated with longevity and cell proliferation, we examined the telomerase response following gamma-irradiation in normal aortic endothelial cells. Telomeric Repeat Amplification Protocol assay following low LET radiation showed an increase in telomerase enzyme activity as early as 8 h post irradiation and reaches its maximum at 24 h. Subsequent analysis revealed that the increased telomerse enzyme activity is due to increased synthesis resulting from an increased transcription. Examination of transcriptional activation of telomerase reverse transcriptase (TERT) promoter regulation showed an enhanced transcription of the telomerse gene following gamma-irradiation. In our previous reports we documented an increase in NF-kB DNA-binding property following low LET radiation (3). Therefore, to determine whether the activation of NF-kB-signaling is responsible for induced TERT promoter activation, cells transiently transfected with minimal promoter region of TERT containing wild type or mutant NF-kB binding site were examined following low LET radiation. TERT promoter activation was induced in wild type transfected cells whereas, in mutant kB binding site, the activation remained at the basal level similar to that of un-irradiated cells. More significantly, the gamma-ray mediated promoter activation of telomerase gene as well as induce telomerase enzyme activity was abrogated by ectopically expressing the IkBa mutant (IkBa (S32A/S36A)), which blocks NF-kB activation. The results thus suggest that exposure to low LET radiation could induce telomerase activity and the activation is at least, in part, mediated by the transcription factor NF-kB. Sustained activation of telomerase in these cells after low LET radiation may impart extended life span

  6. 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

    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...... 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...

  7. Deregulation of acetohydroxy-acid synthase: loss of allosteric inhibition conferred by mutations in the catalytic subunit

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Jan; Kyselková, Martina; Šigutová, Lucie; Pospíšil, Stanislav; Felsberg, Jürgen; Spížek, Jaroslav; Janata, Jiří

    2008-01-01

    Roč. 53, č. 6 (2008), s. 467-471 ISSN 0015-5632 R&D Projects: GA ČR GA204/01/1001; GA ČR GA204/05/0616 Institutional research plan: CEZ:AV0Z50200510 Keywords : acetohydroxy acid * ilvb genes * sequencing Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

  8. Chemistry and engineering of catalytic hydrodesulfurization

    NARCIS (Netherlands)

    Schuit, G.C.A.; Gates, B.C.

    1973-01-01

    A review with 74 refs. on catalytic hydrodesulfurization of pure compds. and petroleum feedstocks, with emphasis on reaction intermediates and structures of Al2O3-supported Ni-W and Co-Mo catalysts. [on SciFinder (R)

  9. Catalytic Aminohalogenation of Alkenes and Alkynes.

    Science.gov (United States)

    Chemler, Sherry R; Bovino, Michael T

    2013-06-07

    Catalytic aminohalogenation methods enable the regio- and stereoselective vicinal difunctionalization of alkynes, allenes and alkenes with amine and halogen moieties. A range of protocols and reaction mechanisms including organometallic, Lewis base, Lewis acid and Brønsted acid catalysis have been disclosed, enabling the regio- and stereoselective synthesis of halogen-functionalized acyclic amines and nitrogen heterocycles. Recent advances including aminofluorination and catalytic enantioselective aminohalogenation reactions are summarized in this review.

  10. Kinetic catalytic studies of scorpion's hemocyanin

    International Nuclear Information System (INIS)

    Queinnec, E.; Vuillaume, M.; Gardes-Albert, M.; Ferradini, C.; Ducancel, F.

    1991-01-01

    Hemocyanins are copper proteins which function as oxygen carriers in the haemolymph of Molluscs and Arthropods. They possess enzymatic properties: peroxidatic and catalatic activities, although they have neither iron nor porphyrin ring at the active site. The kinetics of the catalytic reaction is described. The reaction of superoxide anion with hemocyanin has been studied using pulse radiolysis at pH 9. The catalytic rate constant is 3.5 X 10 7 mol -1 .l.s -1 [fr

  11. Differentially regulated protein kinase A (PKA) activity in adipose tissue and liver is associated with resistance to diet-induced obesity and glucose intolerance in mice that lack PKA regulatory subunit type IIα.

    Science.gov (United States)

    London, Edra; Nesterova, Maria; Sinaii, Ninet; Szarek, Eva; Chanturiya, Tatyana; Mastroyannis, Spyridon A; Gavrilova, Oksana; Stratakis, Constantine A

    2014-09-01

    The cAMP-dependent protein kinase A (PKA) signaling system is widely expressed and has a central role in regulating cellular metabolism in all organ systems affected by obesity. PKA has four regulatory (RIα, RIIα, RIβ, RIIβ) and four catalytic (Cα, Cβ, Cγ, Prkx) subunit isoforms that have tissue-specific expression profiles. In mice, knockout (KO) of RIIβ, the primary PKA regulatory subunit in adipose tissue or knockout of the catalytic subunit Cβ resulted in a lean phenotype that resists diet-induced obesity and associated metabolic complications. Here we report that the disruption of the ubiquitously expressed PKA RIIα subunit in mice (RIIαKO) confers resistance to diet-induced obesity, glucose intolerance, and hepatic steatosis. After 2-week high-fat diet exposure, RIIαKO mice weighed less than wild-type littermates. Over time this effect was more pronounced in female mice that were also leaner than their wild-type counterparts, regardless of the diet. Decreased intake of a high-fat diet contributed to the attenuated weight gain in RIIαKO mice. Additionally, RIIα deficiency caused differential regulation of PKA in key metabolic organs: cAMP-stimulated PKA activity was decreased in liver and increased in gonadal adipose tissue. We conclude that RIIα represents a potential target for therapeutic interventions in obesity, glucose intolerance, and nonalcoholic fatty liver disease.

  12. 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

    OpenAIRE

    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 pum...

  13. A conserved mechanism of autoinhibition for the AMPK kinase domain: ATP-binding site and catalytic loop refolding as a means of regulation

    International Nuclear Information System (INIS)

    Littler, Dene R.; Walker, John R.; Davis, Tara; Wybenga-Groot, Leanne E.; Finerty, Patrick J. Jr; Newman, Elena; Mackenzie, Farell; Dhe-Paganon, Sirano

    2010-01-01

    A 1.9 Å resolution crystal structure of the isolated kinase domain from the α2 subunit of human AMPK, the first from a multicellular organism, is presented. The AMP-activated protein kinase (AMPK) is a highly conserved trimeric protein complex that is responsible for energy homeostasis in eukaryotic cells. Here, a 1.9 Å resolution crystal structure of the isolated kinase domain from the α2 subunit of human AMPK, the first from a multicellular organism, is presented. This human form adopts a catalytically inactive state with distorted ATP-binding and substrate-binding sites. The ATP site is affected by changes in the base of the activation loop, which has moved into an inhibited DFG-out conformation. The substrate-binding site is disturbed by changes within the AMPKα2 catalytic loop that further distort the enzyme from a catalytically active form. Similar structural rearrangements have been observed in a yeast AMPK homologue in response to the binding of its auto-inhibitory domain; restructuring of the kinase catalytic loop is therefore a conserved feature of the AMPK protein family and is likely to represent an inhibitory mechanism that is utilized during function

  14. 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.

  15. 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.

  16. 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)

    Loublier, Sandrine; Bayot, Aurelien; Rak, Malgorzata; El-Khoury, Riyad; Benit, Paule; Rustin, Pierre

    2011-01-01

    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.

  17. Adsorbent catalytic nanoparticles and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-01-31

    The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

  18. 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.

  19. 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...... (Thr37/46) (P mTOR targets, suggesting mTOR signaling is blocked by prior AMPK activation. The AICAR-induced inhibition was partly rescued...

  20. Contributions to the theory of catalytic titrations-III Neutralization catalytic titrations.

    Science.gov (United States)

    Gaál, F F; Abramović, B F

    1985-07-01

    Neutralization catalytic titrations of weak monoprotic adds and bases with both volumetric and coulometric addition of the titrant (strong base/acid) have been simulated by taking into account the equilibrium concentration of the catalyst during the titration. The influence of several factors on the shape of the simulated catalytic titration curve has been investigated and is discussed.

  1. The first transmembrane domain (TM1) of β2-subunit binds to the transmembrane domain S1 of α-subunit in BK potassium channels

    Science.gov (United States)

    Morera, Francisco J.; Alioua, Abderrahmane; Kundu, Pallob; Salazar, Marcelo; Gonzalez, Carlos; Martinez, Agustin D.; Stefani, Enrico; Toro, Ligia; Latorre, Ramon

    2012-01-01

    The BK channel is one of the most broadly expressed ion channels in mammals. In many tissues, the BK channel pore-forming α-subunit is associated to an auxiliary β-subunit that modulates the voltage- and Ca2+-dependent activation of the channel. Structural components present in β-subunits that are important for the physical association with the α-subunit are yet unknown. Here, we show through co-immunoprecipitation that the intracellular C-terminus, the second transmembrane domain (TM2) and the extracellular loop of the β2-subunit are dispensable for association with the α-subunit pointing transmembrane domain 1 (TM1) as responsible for the interaction. Indeed, the TOXCAT assay for transmembrane protein–protein interactions demonstrated for the first time that TM1 of the β2-subunit physically binds to the transmembrane S1 domain of the α-subunit. PMID:22710124

  2. 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.

  3. Atomically Precise Metal Nanoclusters for Catalytic Application

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Rongchao [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-11-18

    The central goal of this project is to explore the catalytic application of atomically precise gold nanoclusters. By solving the total structures of ligand-protected nanoclusters, we aim to correlate the catalytic properties of metal nanoclusters with their atomic/electronic structures. Such correlation unravel some fundamental aspects of nanocatalysis, such as the nature of particle size effect, origin of catalytic selectivity, particle-support interactions, the identification of catalytically active centers, etc. The well-defined nanocluster catalysts mediate the knowledge gap between single crystal model catalysts and real-world conventional nanocatalysts. These nanoclusters also hold great promise in catalyzing certain types of reactions with extraordinarily high selectivity. These aims are in line with the overall goals of the catalytic science and technology of DOE and advance the BES mission “to support fundamental research to understand, predict, and ultimately control matter and energy at the level of electrons, atoms, and molecules”. Our group has successfully prepared different sized, robust gold nanoclusters protected by thiolates, such as Au25(SR)18, Au28(SR)20, Au38(SR)24, Au99(SR)42, Au144(SR)60, etc. Some of these nanoclusters have been crystallographically characterized through X-ray crystallography. These ultrasmall nanoclusters (< 2 nm diameter) exhibit discrete electronic structures due to quantum size effect, as opposed to quasicontinuous band structure of conventional metal nanoparticles or bulk metals. The available atomic structures (metal core plus surface ligands) of nanoclusters serve as the basis for structure-property correlations. We have investigated the unique catalytic properties of nanoclusters (i.e. not observed in conventional nanogold catalysts) and revealed the structure-selectivity relationships. Highlights of our

  4. Analysis of the role of COP9 Signalosome (CSN subunits in K562; the first link between CSN and autophagy

    Directory of Open Access Journals (Sweden)

    Bunce Christopher M

    2009-04-01

    Full Text Available Abstract Background The COP9/signalosome (CSN is a highly conserved eight subunit complex that, by deneddylating cullins in cullin-based E3 ubiquitin ligases, regulates protein degradation. Although studied in model human cell lines such as HeLa, very little is known about the role of the CSN in haemopoietic cells. Results Greater than 95% knockdown of the non-catalytic subunit CSN2 and the deneddylating subunit CSN5 of the CSN was achieved in the human myeloid progenitor cell line K562. CSN2 knockdown led to a reduction of both CSN5 protein and mRNA whilst CSN5 knockdown had little effect on CSN2. Both knockdowns inhibited CSN deneddylase function as demonstrated by accumulation of neddylated Cul1. Furthermore, both knockdowns resulted in the sequential loss of Skp2, Cdc4 and β-TrCP F-box proteins. These proteins were rescued by the proteasome inhibitor MG132, indicating the autocatalytic degradation of F-box proteins upon loss of CSN2 or CSN5. Interestingly, altered F-box protein gene expression was also observed in CSN2 and CSN5 knockdowns, suggesting a potential role of the CSN in regulating F-box protein transcription. Loss of either CSN subunit dramatically reduced cell growth but resulted in distinct patterns of cell death. CSN5 knockdown caused mitotic defects, G2/M arrest and apoptotic cell death. CSN2 knockdown resulted in non-apoptotic cell death associated with accumulation of both the autophagy marker LC3-II and autophagic vacuoles. Treatment of vector control K562 cells with the autophagy inhibitors 3-methyladenine and bafilomycin A1 recapitulated the growth kinetics, vacuolar morphology and LC3-II accumulation of CSN2 knockdown cells indicating that the cellular phenotype of CSN2 cells arises from autophagy inhibition. Finally, loss of CSN2 was associated with the formation of a CSN5 containing subcomplex. Conclusion We conclude that CSN2 is required for CSN integrity and the stability of individual CSN subunits, and postulate

  5. 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.

  6. Things I Have Learned about Meta-Analysis Since 1990: Reducing Bias in Search of “The Big Picture” / Ce que j’ai appris sur la méta-analyse depuis 1990 : réduire les partis pris en quête d’une vue d’ensemble

    Directory of Open Access Journals (Sweden)

    Robert M Bernard

    2014-12-01

    Full Text Available This paper examines sources of potential bias in systematic reviews and meta-analyses which can distort their findings, leading to problems with interpretation and application by practitioners and policymakers. It follows from an article that was published in the Canadian Journal of Communication in 1990, “Integrating Research into Instructional Practice: The Use and Abuse of Meta-analysis,” which introduced meta-analysis as a means for estimating population parameters and summarizing quantitative research around instructional research questions. This paper begins by examining two cases where multiple meta-analyses disagree. It then goes on to describe substantive and methodological aspects of meta-analysis where various kinds of bias can influence the outcomes and suggests measures that can be taken to avoid them. The intention is to improve the reliability and accuracy of reviews so that practitioners can trust the results and use them more effectively. Cet article examine les sources des partis pris potentiels dans les synthèses systématiques et les méta-analyses qui peuvent déformer les conclusions, ce qui peut causer des problèmes d’interprétation et d’application par les praticiens et les responsables des politiques. Il fait suite à un article publié dans le Canadian Journal of Communication en 1990, intitulé « Integrating Research into Instructional Practice: The Use and Abuse of Meta-analysis », qui présentait la méta-analyse comme moyen d’estimer les paramètres relatifs à la population et de résumer la recherche quantitative sur les questions de recherche pédagogique. L’article commence avec l’examen de deux cas dans lesquels de nombreuses méta-analyses sont en désaccord. Il décrit ensuite les aspects substantifs et méthodologiques des méta-analyses dans lesquels divers types de partis pris peuvent influencer les résultats et suggère des mesures qui peuvent être adoptées pour éviter ces partis

  7. Binding mechanism and dynamic conformational change of C subunit of PKA with different pathways.

    Science.gov (United States)

    Chu, Wen-Ting; Chu, Xiakun; Wang, Jin

    2017-09-19

    The catalytic subunit of PKA (PKAc) exhibits three major conformational states (open, intermediate, and closed) during the biocatalysis process. Both ATP and substrate/inhibitor can effectively induce the conformational changes of PKAc from open to closed states. Aiming to explore the mechanism of this allosteric regulation, we developed a coarse-grained model and analyzed the dynamics of conformational changes of PKAc during binding by performing molecular dynamics simulations for apo PKAc, binary PKAc (PKAc with ATP, PKAc with PKI), and ternary PKAc (PKAc with ATP and PKI). Our results suggest a mixed binding mechanism of induced fit and conformational selection, with the induced fit dominant. The ligands can drive the movements of Gly-rich loop as well as some regions distal to the active site in PKAc and stabilize them at complex state. In addition, there are two parallel pathways (pathway with PKAc-ATP as an intermediate and pathway PKAc-PKI as an intermediate) during the transition from open to closed states. By molecular dynamics simulations and rate constant analyses, we find that the pathway through PKAc-ATP intermediate is the main binding route from open to closed state because of the fact that the bound PKI will hamper ATP from successful binding and significantly increase the barrier for the second binding subprocess. These findings will provide fundamental insights of the mechanisms of PKAc conformational change upon binding.

  8. Molecular Cloning and Characterization of the Calcineurin Subunit A from Plutella xylostella

    Directory of Open Access Journals (Sweden)

    Xi'en Chen

    2013-10-01

    Full Text Available Calcineurin (or PP2B has been reported to be involved in an array of physiological process in insects, and the calcineurin subunit A (CNA plays a central role in calcineurin activity. We cloned the CNA gene from Plutella xylostella (PxCNA. This gene contains an ORF of 1488 bp that encodes a 495 amino acid protein, showing 98%, and 80% identities to the CNA of Bombyx mori, and humans respectively. The full-length of PxCNA and its catalytic domain (CNA1–341, defined as PxCNα were both expressed in Escherichia coli. Purified recombinant PxCNA displayed no phosphatase activity, whereas recombinant PxCNα showed high phosphatase activity with a Km of 4.6 mM and a kcat of 0.66 S−1 against pNPP. It could be activated at different degrees by Mn2+, Ni2+, Mg2+, and Ca2+. The optimum reaction pH was about 7.5 and the optimum reaction temperature was around 45 °C. An in vitro inhibition assay showed that okadaic acid (OA and cantharidin (CTD competitively inhibited recombinant PxCNα activity with the IC50 values of 8.95 μM and 77.64 μM, respectively. However, unlike previous reports, pyrethroid insecticides were unable to inhibit recombinant PxCNα, indicating that the P. xylostella calcineurin appears not to be sensitive to class II pyrethroid insecticides.

  9. Mitochondrial DNA polymerase from embryos of Drosophila melanogaster: purification, subunit structure, and partial characterization

    International Nuclear Information System (INIS)

    Wernette, C.M.; Kaguni, L.S.

    1986-01-01

    The mitochondrial DNA polymerase has been purified to near-homogeneity from early embryos of Drosophila melanogaster. Sodium dodecyl sulfate gel electrophoresis of the highly purified enzyme reveals two polypeptides with molecular masses of 125,000 and 35,000 daltons, in a ratio of 1:1. The enzyme has a sedimentation coefficient of 7.6 S and a stokes radius of 51 A. Taken together, the data suggest that the D. melanogaster DNA polymerase γ is a heterodimer. DNA polymerase activity gel analysis has allowed the assignment of the DNA polymerization function to the large subunit. The DNA polymerase exhibits a remarkable ability to utilize efficiently a variety of template-primers including gapped DNA, poly(rA).oligo(dT) and singly primed phiX174 DNA. Both the crude and the highly purified enzymes are stimulated by KCl, and inhibited by dideoxythymidine triphosphate and by N-ethylmaleimide. Thus, the catalytic properties of the near-homogeneous Drosophila enzyme are consistent with those of DNA polymerase γ as partially purified from several vertebrates

  10. Novel subunit structure observed for noncooperative hemoglobin from Urechis caupo.

    Science.gov (United States)

    Kolatkar, P R; Meador, W E; Stanfield, R L; Hackert, M L

    1988-03-05

    Tetrameric hemoglobin from the "fat innkeeper" worm Urechis caupo possesses a novel subunit arrangement having an "inside out" quaternary structure in that the G/H helices are located on the outer surface of the tetramer. A 5-A resolution crystal structure reveals that although the individual subunits are beta-like, having a distinct D helix and the general myoglobin fold, the subunit contacts are very different from those previously observed for hemoglobins. Furthermore, the hemoglobin from U. caupo is also quite different from the unusual hemoglobin tetramer from clam which also has its G/H helices on the outer surface but with the hemes in close proximity through E-F helical contacts (Royer, W. E., Jr., Love, W. E., and Fenderson, F. F. (1985) Nature 316, 277-280).

  11. Dynamic properties of motor proteins with two subunits

    International Nuclear Information System (INIS)

    Kolomeisky, Anatoly B; III, Hubert Phillips

    2005-01-01

    The dynamics of motor protein molecules consisting of two subunits is investigated using simple discrete stochastic models. Exact steady-state analytical expressions are obtained for velocities and dispersions for any number of intermediate states and conformations between the corresponding binding states of proteins. These models enable us to provide a detailed description and comparison of two different mechanisms of the motion of motor proteins along the linear tracks: the hand-over-hand mechanism, when the motion of subunits alternate; and the inchworm mechanism, when one subunit is always trailing another one. It is shown that the proteins in the hand-over-hand mechanism move faster and fluctuate more than the molecules in the inchworm mechanism. The effect of external forces on dynamic properties of motor proteins is also discussed. Finally, a quantitative method, based on experimental observations for single motor proteins, is proposed for distinguishing between two mechanisms of motion

  12. CSNAP Is a Stoichiometric Subunit of the COP9 Signalosome

    Directory of Open Access Journals (Sweden)

    Shelly Rozen

    2015-10-01

    Full Text Available The highly conserved COP9 signalosome (CSN complex is a key regulator of all cullin-RING-ubiquitin ligases (CRLs, the largest family of E3 ubiquitin ligases. Until now, it was accepted that the CSN is composed of eight canonical components. Here, we report the discovery of an additional integral and stoichiometric subunit that had thus far evaded detection, and we named it CSNAP (CSN acidic protein. We show that CSNAP binds CSN3, CSN5, and CSN6, and its incorporation into the CSN complex is mediated through the C-terminal region involving conserved aromatic residues. Moreover, depletion of this small protein leads to reduced proliferation and a flattened and enlarged morphology. Finally, on the basis of sequence and structural properties shared by both CSNAP and DSS1, a component of the related 19S lid proteasome complex, we propose that CSNAP, the ninth CSN subunit, is the missing paralogous subunit of DSS1.

  13. 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.

  14. 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...... strong immune responses. This review highlights the status and recent advances in formulation and pulmonary delivery of thermostable human subunit vaccines. Such vaccines are very appealing from compliance, distribution and immunological point of view: Being non-invasive, inhalable vaccines are self...... immunity. Here, I review state of the art and perspectives in formulation design and processing methods for powder-based subunit vaccines intended for pulmonary administration, and present dry powder inhaler technologies suitable for translating these vaccines into clinical trials....

  15. Differences in the roles of a glutamine amidotransferase subunit of pyridoxal 5'-phosphate synthase between Bacillus circulans and Bacillus subtilis.

    Science.gov (United States)

    Itagaki, Shiori; Haga, Minami; Oikawa, Yuji; Sakoda, Ayaka; Ohke, Yoshie; Sawada, Hiroshi; Eguchi, Tadashi; Tamegai, Hideyuki

    2013-01-01

    BtrC2 of the butirosin producer Bacillus circulans is a non-catalytic subunit of 2-deoxy-scyllo-inosose (DOI) synthase that is involved in butirosin biosynthesis, and also a homolog of glutamine amidotransferase subunit (PdxT) of pyridoxal 5'-phosphate (PLP) synthase of Bacillus subtilis. BtrC2 has been found to have functions in B. circulans both in primary and secondary metabolism. In this study, we investigated the properties of PdxT of B. subtilis in order to determine whether the property of enzyme stabilization is universal among PdxT homologs. Complementation with PdxT in the btrC2 disruptant of B. circulans restored the growth and short-term production of antibiotics, but long-term production of antibiotics cannot be restored. Additionally, PdxT did not bind physically with or stabilize BtrC. Our results indicate that the function of BtrC2 in secondary metabolism is specific properties, not universal among PdxT homologs.

  16. 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.

  17. 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.

  18. 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...

  19. Modeling and simulation of heterogeneous catalytic processes

    CERN Document Server

    Dixon, Anthony

    2014-01-01

    Heterogeneous catalysis and mathematical modeling are essential components of the continuing search for better utilization of raw materials and energy, with reduced impact on the environment. Numerical modeling of chemical systems has progressed rapidly due to increases in computer power, and is used extensively for analysis, design and development of catalytic reactors and processes. This book presents reviews of the state-of-the-art in modeling of heterogeneous catalytic reactors and processes. Reviews by leading authorities in the respective areas Up-to-date reviews of latest techniques in modeling of catalytic processes Mix of US and European authors, as well as academic/industrial/research institute perspectives Connections between computation and experimental methods in some of the chapters.

  20. Subunit rotation in a single FoF1-ATP synthase in a living bacterium monitored by FRET

    Science.gov (United States)

    Seyfert, K.; Oosaka, T.; Yaginuma, H.; Ernst, S.; Noji, H.; Iino, R.; Börsch, M.

    2011-03-01

    FoF1-ATP synthase is the ubiquitous membrane-bound enzyme in mitochondria, chloroplasts and bacteria which provides the 'chemical energy currency' adenosine triphosphate (ATP) for cellular processes. In Escherichia coli ATP synthesis is driven by a proton motive force (PMF) comprising a proton concentration difference ΔpH plus an electric potential ΔΨ across the lipid membrane. Single-molecule in vitro experiments have confirmed that proton-driven subunit rotation within FoF1-ATP synthase is associated with ATP synthesis. Based on intramolecular distance measurements by single-molecule fluorescence resonance energy transfer (FRET) the kinetics of subunit rotation and the step sizes of the different rotor parts have been unraveled. However, these experiments were accomplished in the presence of a PMF consisting of a maximum ΔpH ~ 4 and an unknown ΔΨ. In contrast, in living bacteria the maximum ΔpH across the plasma membrane is likely 0.75, and ΔΨ has been measured between -80 and -140 mV. Thus the problem of in vivo catalytic turnover rates, or the in vivo rotational speed in single FoF1-ATP synthases, respectively, has to be solved. In addition, the absolute number of functional enzymes in a single bacterium required to maintain the high ATP levels has to be determined. We report our progress of measuring subunit rotation in single FoF1-ATP synthases in vitro and in vivo, which was enabled by a new labeling approach for single-molecule FRET measurements.

  1. Protein Kinase A Regulatory Subunit Isoforms Regulate Growth and Differentiation in Mucor circinelloides: Essential Role of PKAR4

    Science.gov (United States)

    Ocampo, J.; McCormack, B.; Navarro, E.; Moreno, S.; Garre, V.

    2012-01-01

    The protein kinase A (PKA) signaling pathway plays a role in regulating growth and differentiation in the dimorphic fungus Mucor circinelloides. PKA holoenzyme is comprised of two catalytic (C) and two regulatory (R) subunits. In M. circinelloides, four genes encode the PKAR1, PKAR2, PKAR3, and PKAR4 isoforms of R subunits. We have constructed null mutants and demonstrate that each isoform has a different role in growth and differentiation. The most striking finding is that pkaR4 is an essential gene, because only heterokaryons were obtained in knockout experiments. Heterokaryons with low levels of wild-type nuclei showed an impediment in the emission of the germ tube, suggesting a pivotal role of this gene in germ tube emergence. The remaining null strains showed different alterations in germ tube emergence, sporulation, and volume of the mother cell. The pkaR2 null mutant showed an accelerated germ tube emission and was the only mutant that germinated under anaerobic conditions when glycine was used as a nitrogen source, suggesting that pkaR2 participates in germ tube emergence by repressing it. From the measurement of the mRNA and protein levels of each isoform in the wild-type and knockout strains, it can be concluded that the expression of each subunit has its own mechanism of differential regulation. The PKAR1 and PKAR2 isoforms are posttranslationally modified by ubiquitylation, suggesting another regulation point in the specificity of the signal transduction. The results indicate that each R isoform has a different role in M. circinelloides physiology, controlling the dimorphism and contributing to the specificity of cyclic AMP (cAMP)-PKA pathway. PMID:22635921

  2. 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.

    2015-01-01

    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. PMID:26306040

  3. Managing brain extracellular K+ during neuronal activity: The physiological role of the Na+/K+-ATPase subunit isoforms

    Directory of Open Access Journals (Sweden)

    Brian Roland eLarsen

    2016-04-01

    Full Text Available AbstractDuring neuronal activity in the brain, extracellular K+ rises and is subsequently removed to prevent a widespread depolarization. One of the key players in regulating extracellular K+ is the Na+/K+-ATPase, although the relative involvement and physiological impact of the different subunit isoform compositions of the Na+/K+-ATPase remain unresolved. The various cell types in the brain serve a certain temporal contribution in the face of network activity; astrocytes respond directly to the immediate release of K+ from neurons, whereas the neurons themselves become the primary K+ absorbers as activity ends. The kinetic characteristics of the catalytic α subunit isoforms of the Na+/K+-ATPase are, partly, determined by the accessory β subunit with which they combine. The isoform combinations expressed by astrocytes and neurons, respectively, appear to be in line with the kinetic characteristics required to fulfill their distinct physiological roles in clearance of K+ from the extracellular space in the face of neuronal activity.Understanding the nature, impact and effects of the various Na+/K+-ATPase isoform combinations in K+ management in the central nervous system might reveal insights into pathological conditions such as epilepsy, migraine, and spreading depolarization following cerebral ischemia. In addition, particular neurological diseases occur as a result of mutations in the α2- (familial hemiplegic migraine type 2 and α3 isoforms (rapid-onset dystonia parkinsonism/alternating hemiplegia of childhood. This review addresses aspects of the Na+/K+-ATPase in the regulation of extracellular K+ in the central nervous system as well as the related pathophysiology. Understanding the physiological setting in non-pathological tissue would provide a better understanding of the pathological events occurring during disease.

  4. Functional analysis of the glycogen binding subunit CG9238/Gbs-70E of protein phosphatase 1 in Drosophila melanogaster.

    Science.gov (United States)

    Kerekes, Éva; Kókai, Endre; Páldy, Ferenc Sándor; Dombrádi, Viktor

    2014-06-01

    The product of the CG9238 gene that we termed glycogen binding subunit 70E (Gbs-70E) was characterized by biochemical and molecular genetics methods. The interaction between Gbs-70E and all catalytic subunits of protein phosphatase 1 (Pp1-87B, Pp1-9C, Pp1-96A and Pp1-13C) of Drosophila melanogaster was confirmed by pairwise yeast two-hybrid tests, co-immunoprecipitation and pull down experiments. The binding of Gbs-70E to glycogen was demonstrated by sedimentation analysis. With RT-PCR we found that the mRNAs coding for the longer Gbs-70E PB/PC protein were expressed in all developmental stages of the fruit flies while the mRNA for the shorter Gbs-70E PA was restricted to the eggs and the ovaries of the adult females. The development specific expression of the shorter splice variant was not conserved in different Drosophila species. The expression level of the gene was manipulated by P-element insertions and gene deletion to analyze the functions of the gene product. A small or moderate reduction in the gene expression resulted in no significant changes, however, a deletion mutant expressing very low level of the transcript lived shorter and exhibited reduced glycogen content in the imagos. In addition, the gene deletion decreased the fertility of the fruit flies. Our results prove that Gbs-70E functions as the glycogen binding subunit of protein phosphatase 1 that regulates glycogen content and plays a role in the development of eggs in D. melanogaster. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Catalytic Wastewater Treatment Using Pillared Clays

    Science.gov (United States)

    Perathoner, Siglinda; Centi, Gabriele

    After introduction on the use of solid catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), this review discussed the use of pillared clay (PILC) materials in three applications: (i) wet air catalytic oxidation (WACO), (ii) wet hydrogen peroxide catalytic oxidation (WHPCO) on Cu-PILC and Fe-PILC, and (iii) behavior of Ti-PILC and Fe-PILC in the photocatalytic or photo-Fenton conversion of pollutants. Literature data are critically analyzed to evidence the main direction to further investigate, in particularly with reference to the possible practical application of these technologies to treat industrial, municipal, or agro-food production wastewater.

  7. Catalytic Kinetic Resolution of Biaryl Compounds.

    Science.gov (United States)

    Ma, Gaoyuan; Sibi, Mukund P

    2015-08-10

    Biaryl compounds with axial chirality are very common in synthetic chemistry, especially in catalysis. Axially chiral biaryls are important due to their biological activities and extensive applications in asymmetric catalysis. Thus the development of efficient enantioselective methods for their synthesis has attracted considerable attention. This Minireview discusses the progress made in catalytic kinetic resolution of biaryl compounds and chronicles significant advances made recently in catalytic kinetic resolution of biaryl scaffolds. © 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. 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.

  9. Janus droplet as a catalytic micromotor

    Science.gov (United States)

    Shklyaev, Sergey

    2015-06-01

    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 μ \\text{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 the Janus one no stability threshold exists; hence, the droplet radius can be scaled down to micrometers.

  10. Catalytic burners in larger boiler appliances

    Energy Technology Data Exchange (ETDEWEB)

    Silversand, Fredrik; Persson, Mikael (Catator AB, Lund (Sweden))

    2009-02-15

    This project focuses on the scale up of a Catator's catalytic burner technology to enable retrofit installation in existing boilers and the design of new innovative combinations of catalytic burners and boilers. Different design approaches are discussed and evaluated in the report and suggestions are made concerning scale-up. Preliminary test data, extracted from a large boiler installation are discussed together with an accurate analysis of technical possibilities following an optimization of the boiler design to benefit from the advantages of catalytic combustion. The experimental work was conducted in close collaboration with ICI Caldaie (ICI), located in Verona, Italy. ICI is a leading European boiler manufacturer in the effect segment ranging from about 20 kWt to several MWt. The study shows that it is possibly to scale up the burner technology and to maintain low emissions. The boilers used in the study were designed around conventional combustion and were consequently not optimized for implementation of catalytic burners. From previous experiences it stands clear that the furnace volume can be dramatically decreased when applying catalytic combustion. In flame combustion, this volume is normally dimensioned to avoid flame impingement on cold surfaces and to facilitate completion of the gas-phase reactions. The emissions of nitrogen oxides can be reduced by decreasing the residence time in the furnace. Even with the over-dimensioned furnace used in this study, we easily reached emission values close to 35 mg/kWh. The emissions of carbon monoxide and unburned hydrocarbons were negligible (less than 5 ppmv). It is possible to decrease the emissions of nitrogen oxides further by designing the furnace/boiler around the catalytic burner, as suggested in the report. Simultaneously, the size of the boiler installation can be reduced greatly, which also will result in material savings, i.e. the production cost can be reduced. It is suggested to optimize the

  11. 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.)

  12. Using electron beams to investigate catalytic materials

    International Nuclear Information System (INIS)

    Zhang, Bingsen; Su, Dang Sheng

    2014-01-01

    Transmission Electron microscopy (TEM) enables us, not only to reveal the morphology, but also to provide structural, chemical and electronic information about solid catalysts at the atomic level, providing a dramatic driving force for the development of heterogeneous catalysis. Almost all catalytic materials have been studied with TEM in order to obtain information about their structures, which can help us to establish the synthesis-structure-property relationships and to design catalysts with new structures and desired properties. Herein, several examples will be reviewed to illustrate the investigation of catalytic materials by using electron beams. (authors)

  13. Direct interaction of the inhibitory gamma-subunit of Rod cGMP phosphodiesterase (PDE6) with the PDE6 GAFa domains.

    Science.gov (United States)

    Muradov, Khakim G; Granovsky, Alexey E; Schey, Kevin L; Artemyev, Nikolai O

    2002-03-26

    Retinal rod and cone cGMP phosphodiesterases (PDE6 family) function as the effector enzyme in the vertebrate visual transduction cascade. The activity of PDE6 catalytic subunits is controlled by the Pgamma-subunits. In addition to the inhibition of cGMP hydrolysis at the catalytic sites, Pgamma is known to stimulate a noncatalytic binding of cGMP to the regulatory GAFa-GAFb domains of PDE6. The latter role of Pgamma has been attributed to its polycationic region. To elucidate the structural basis for the regulation of cGMP binding to the GAF domains of PDE6, a photoexcitable peptide probe corresponding to the polycationic region of Pgamma, Pgamma-21-45, was specifically cross-linked to rod PDE6alphabeta. The site of Pgamma-21-45 cross-linking was localized to Met138Gly139 within the PDE6alpha GAFa domain using mass spectrometric analysis. Chimeras between PDE5 and cone PDE6alpha', containing GAFa and/or GAFb domains of PDE6alpha' have been generated to probe a potential role of the GAFb domains in binding to Pgamma. Analysis of the inhibition of the PDE5/PDE6alpha' chimeras by Pgamma supported the role of PDE6 GAFa but not GAFb domains in the interaction with Pgamma. Our results suggest that a direct binding of the polycationic region of Pgamma to the GAFa domains of PDE6 may lead to a stabilization of the noncatalytic cGMP-binding sites.

  14. Da Casa de Detenção à Colônia Penal “Doutor João Chaves”: o processo de afastamento da prisão em relação ao espaço urbano da cidade de Natal (1940-1975)

    OpenAIRE

    Silva, Aldenise Regina Lira da

    2015-01-01

    Em 1970, foi desativada a Casa de Detenção de Natal, localizada no bairro de Petrópolis, sendo substituída pela Colônia Penal “Doutor João Chaves”, situada em um ambiente de características rurais, o distrito de Igapó. Porém, o processo que levou a esse afastamento da prisão em relação ao espaço urbano de Natal havia começado três décadas antes. A fundação da Colônia Penal “Doutor João Chaves” no município de Macaíba, e posteriormente, sua transferência para Igapó, no município de Natal, envo...

  15. Mutation in rod PDE6 linked to congenital stationary night blindness impairs the enzyme inhibition by its gamma-subunit.

    Science.gov (United States)

    Muradov, Khakim G; Granovsky, Alexey E; Artemyev, Nikolai O

    2003-03-25

    Photoreceptor cGMP phosphodiesterase (PDE6) is the effector enzyme in the vertebrate visual transduction cascade. The activity of rod PDE6 catalytic alpha- and beta-subunits is blocked in the dark by two inhibitory Pgamma-subunits. The inhibition is released upon light-stimulation of photoreceptor cells. Mutation H258N in PDE6beta has been linked to congenital stationary night blindness (CSNB) in a large Danish family (Rambusch pedigree) (Gal, A., Orth, U., Baehr, W., Schwinger, E., and Rosenberg, T. (1994) Nat. Genet. 7, 64-67.) We have analyzed the consequences of this mutation for PDE6 function using a Pgamma-sensitive PDE6alpha'/PDE5 chimera, Chi16. Biochemical analysis of the H257N mutant, an equivalent of PDE6betaH258N, demonstrates that this substitution does not alter the ability of chimeric PDE to dimerize or the enzyme's catalytic properties. The sensitivity of H257N to a competitive inhibitor zaprinast was also unaffected. However, the mutant displayed a significant impairment in the inhibitory interaction with Pgamma, which was apparent from a approximately 20-fold increase in the K(i) value (46 nM) and incomplete maximal inhibition. The inhibitory defect of H257N is not due to perturbation of noncatalytic cGMP binding to the PDE6alpha' GAF domains. The noncatalytic cGMP-binding characteristics of the H257N mutant were similar to those of the parent PDE6alpha'/PDE5 chimera. Since rod PDE6 in the Rambusch CSNB is a catalytic heterodimer of the wild-type PDE6alpha and mutant PDE6beta, Chi16 and H257N were coexpressed, and a heterodimeric PDE, Chi16/H257N, was isolated. It displayed two Pgamma inhibitory sites with the K(i) values of 5 and 57 nM. Our results support the hypothesis that mutation H258N in PDE6beta causes CSNB through incomplete inhibition of PDE6 activity by Pgamma, which leads to desensitization of rod photoreceptors.

  16. Evaluation of subunit vaccines against feline immunodeficiency virus infection

    NARCIS (Netherlands)

    Horzinek, M.C.; Verschoor, E.J.; Willemse, M.J.; Stam, J.G.; Vliet, A.L.W. van; Pouwels, H.; Chalmers, S.K.; Sondermeijer, P.J.; Hesselink, W.; Ronde, A. de

    1996-01-01

    Subunit vaccines prepared against feline immunodeficiency virus (FIV) infection were evaluated in two trials. First, cats were immunized with bacterial expression products of an envelope fragment that contained the V3 neutralization domain of the FIV surface protein fused to either galactokinase

  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...

  18. Therapeutic potential of Mediator complex subunits in metabolic diseases.

    Science.gov (United States)

    Ranjan, Amol; Ansari, Suraiya A

    2018-01-01

    The multisubunit Mediator is an evolutionary conserved transcriptional coregulatory complex in eukaryotes. It is needed for the transcriptional regulation of gene expression in general as well as in a gene specific manner. Mediator complex subunits interact with different transcription factors as well as components of RNA Pol II transcription initiation complex and in doing so act as a bridge between gene specific transcription factors and general Pol II transcription machinery. Specific interaction of various Mediator subunits with nuclear receptors (NRs) and other transcription factors involved in metabolism has been reported in different studies. Evidences indicate that ligand-activated NRs recruit Mediator complex for RNA Pol II-dependent gene transcription. These NRs have been explored as therapeutic targets in different metabolic diseases; however, they show side-effects as targets due to their overlapping involvement in different signaling pathways. Here we discuss the interaction of various Mediator subunits with transcription factors involved in metabolism and whether specific interaction of these transcription factors with Mediator subunits could be potentially utilized as therapeutic strategy in a variety of metabolic diseases. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  19. α-4 subunit of nicotinic acetylcholine receptor polymorphisms exhibit ...

    African Journals Online (AJOL)

    Background: Smoking behavior is influenced by both genetic and environmental factors. Nicotine is the major addictive substance in cigarettes. Nicotinic acetylcholine receptors (nAChRs) are thought to play an important role in nicotine addiction of smokers. One of the genes, α-4 subunit of nicotinic acetylcholine receptor ...

  20. Structural interaction of novel dendrimer and subunits with water

    African Journals Online (AJOL)

    Preferred Customer

    interaction study with solvents are essential [4-6] and several subunits are used for .... slowed down the viscous flow with higher excess limiting viscosities of the 2,4,6- ..... Practical Organic Chemistry, 5th ed.; Wiley: New York; 1989; p 300. 14.

  1. 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

  2. Moessbauer spectroscopic studies of hemoglobin and its isolated subunits

    International Nuclear Information System (INIS)

    Hoy, G.R.; Cook, D.C.; Berger, R.L.; Friedman, F.K.

    1986-01-01

    Samples of 90% enriched 57Fe hemoglobin and its isolated subunits have been prepared. Moessbauer spectroscopic measurements have been made on three such samples. Sample one contained contributions of oxyhemoglobin, deoxyhemoglobin, and carbonmonoxyhemoglobin. This sample was studied from a temperature of 90 K down to 230 mK. Measurements were also made at 4.2 K using a small applied magnetic field of 1.0 T. In general, the measured quadrupole splittings and isomer shifts for each component agreed with previous measurements on single component samples in the literature, and thus demonstrated that chemically enriched hemoglobin has not been altered. The second and third samples were isolated alpha and beta subunits, respectively. We have found measurable Moessbauer spectral differences between the HbO 2 sites in the alpha subunit sample and the beta subunit sample. The measured Moessbauer spectral areas indicate that the iron ion has the largest mean-square displacement at the deoxy Hb sites as compared to that at the oxy- and carbonmonoxy Hb sites. The mean-square displacement at the HbO 2 sites is the smallest

  3. Fluid catalytic cracking : Feedstocks and reaction mechanism

    NARCIS (Netherlands)

    Dupain, X.

    2006-01-01

    The Fluid Catalytic Cracking (FCC) process is one of the key units in a modern refinery. Traditionally, its design is primarily aimed for the production of gasoline from heavy oil fractions, but as co-products also diesel blends and valuable gasses (e.g. propene and butenes) are formed in

  4. Kinetic equation of heterogeneous catalytic isotope exchange

    Energy Technology Data Exchange (ETDEWEB)

    Trokhimets, A I [AN Belorusskoj SSR, Minsk. Inst. Fiziko-Organicheskoj Khimii

    1979-12-01

    A kinetic equation is derived for the bimolecular isotope exchange reaction between AXsub(n)sup(*) and BXsub(m)sup(o), all atoms of element X in each molecule being equivalent. The equation can be generalized for homogeneous and heterogeneous catalytic isotope exchange.

  5. Complementary structure sensitive and insensitive catalytic relationships

    NARCIS (Netherlands)

    Santen, van R.A.

    2009-01-01

    The burgeoning field of nanoscience has stimulated an intense interest in properties that depend on particle size. For transition metal particles, one important property that depends on size is catalytic reactivity, in which bonds are broken or formed on the surface of the particles. Decreased

  6. 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…

  7. 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...... understanding of the nature of the electrochemical promotion is also presented....

  8. 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.

  9. 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....

  10. CATALYTIC SPECTROPHOTOMETRIC DETERMINATION OF Mn(II ...

    African Journals Online (AJOL)

    Preferred Customer

    method is based on the catalytic effect of Mn(II) with the oxidation of Celestine blue .... water samples were filtered through a 0.45 μm pore size membrane filter to remove suspended .... slope of the calibration graph as the optimization criterion. ..... In presence of Phen as stability enhancement agent in indicator system. ( ) +.

  11. Catalytic asymmetric synthesis of the alkaloid (+)-myrtine

    NARCIS (Netherlands)

    Pizzuti, Maria Gabriefla; Minnaard, Adriaan J.; Feringa, Ben L.

    2008-01-01

    A new protocol for the asymmetric synthesis of trans-2,6-disubstituted-4-piperidones has been developed using a catalytic enantioselective conjugate addition reaction in combination with a diastereoselective lithiation-substitution sequence; an efficient synthesis of (+)-myrtine has been achieved

  12. Catalytic oxidation of cyclohexane to cyclohexanone

    Indian Academy of Sciences (India)

    ... a precursor and characterized by chemical analysis using the ICP–AES method, XRD, TEM, FTIR and BET surface area determination. The oxidation reaction was carried out at 70°C under atmospheric pressure. The results showed the catalytic performance of Pt/Al2O3 as being very high in terms of turnover frequency.

  13. 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...

  14. Flame assisted synthesis of catalytic ceramic membranes

    DEFF Research Database (Denmark)

    Johansen, Johnny; Mosleh, Majid; Johannessen, Tue

    2004-01-01

    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...

  15. Sintering of Catalytic Nanoparticles: Particle Migration or Ostwald Ripening?

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; DeLaRiva, Andrew T.; Challa, Sivakumar R.

    2013-01-01

    deactivation, is an important mechanism for the loss of catalyst activity. This is especially true for high temperature catalytic processes, such as steam reforming, automotive exhaust treatment, or catalytic combustion. With dwindling supplies of precious metals and increasing demand, fundamental...

  16. Catalytic characterization of bi-functional catalysts derived from Pd ...

    Indian Academy of Sciences (India)

    Unknown

    1995; Lyubovsky and Pfefferle 1999; Sales et al 1999;. Hill et al 2000). ... For a catalytic system, whose activity ... catalytic systems containing Pd, supported on various acid- ..... Further studies are needed to optimize a balance between.

  17. Catalytically favorable surface patterns in Pt-Au nanoclusters

    KAUST Repository

    Mokkath, Junais Habeeb; Schwingenschlö gl, Udo

    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

  18. Maternal high fat diet alters skeletal muscle mitochondrial catalytic activity in adult male rat offspring.

    Directory of Open Access Journals (Sweden)

    Chantal Anne Pileggi

    2016-11-01

    Full Text Available A maternal high-fat (HF diet during pregnancy can lead to metabolic compromise such as insulin resistance in adult offspring. Skeletal muscle mitochondrial dysfunction is one mechanism contributing to metabolic impairments in insulin resistant states. Therefore, the present study aimed to investigate whether mitochondrial dysfunction is evident in metabolically compromised offspring born to HF-fed dams. Sprague-Dawley dams were randomly assigned to receive a purified control diet (CD; 10% kcal from fat or a high fat diet (HFD; 45% kcal from fat for 10 days prior to mating, throughout pregnancy and during lactation. From weaning, all male offspring received a standard chow diet and soleus muscle was collected at day 150. Expression of the mitochondrial transcription factors nuclear respiratory factor-1 (NRF1 and mitochondrial transcription factor A (mtTFA were downregulated in HF offspring. Furthermore, genes encoding the mitochondrial electron transport system (ETS respiratory complex subunits were supressed in HF offspring. Moreover, protein expression of the complex I subunit, NDUFB8, was downregulated in HF offspring (36%, which was paralleled by decreased maximal catalytic linked activity of complex I and III (40%. Together, these results indicate that exposure to a maternal HF diet during development may elicit lifelong mitochondrial alterations in offspring skeletal muscle.

  19. Catalytic Characteristics of New Antibacterials Based on Hexahistidine-Containing Organophosphorus Hydrolase

    Directory of Open Access Journals (Sweden)

    Olga Maslova

    2017-09-01

    Full Text Available Catalytic characteristics of hexahistidine-containing organophosphorus hydrolase (His6-OPH and its enzyme-polyelectrolyte complexes with poly-l-glutamic acid or poly-l-aspartic acid (His6-OPH/PLD50, hydrolyzing organophosphorous compounds, and N-acyl homoserine lactones were studied in the presence of various antibiotics (ampicillin, gentamicin, kanamycin, and rifampicin. The antibiotics at concentrations below 1 g·L−1 had a negligible inhibiting effect on the His6-OPH activity. Mixed inhibition of His6-OPH was established for higher antibiotic concentrations, and rifampicin was the most potent inhibitor. Stabilization of the His6-OPH activity was observed in the presence of antibiotics at a concentration of 0.2 g·L−1 during exposure at 25–41 °C. Molecular docking of antibiotics to the surface of His6-OPH dimer revealed the antibiotics binding both to the area near active centers of the enzyme subunits and to the region of contact between subunits of the dimer. Such interactions between antibiotics and His6-OPH were verified with Fourier-transform infrared (FTIR spectroscopy. Considering all the results of the study, the combination of His6-OPH/PLD50 with β-lactam antibiotic ampicillin was established as the optimal one in terms of exhibition and persistence of maximal lactonase activity of the enzyme.

  20. 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.

  1. Catalytic site identification—a web server to identify catalytic site structural matches throughout PDB

    Science.gov (United States)

    Kirshner, Daniel A.; Nilmeier, Jerome P.; Lightstone, Felice C.

    2013-01-01

    The catalytic site identification web server provides the innovative capability to find structural matches to a user-specified catalytic site among all Protein Data Bank proteins rapidly (in less than a minute). The server also can examine a user-specified protein structure or model to identify structural matches to a library of catalytic sites. Finally, the server provides a database of pre-calculated matches between all Protein Data Bank proteins and the library of catalytic sites. The database has been used to derive a set of hypothesized novel enzymatic function annotations. In all cases, matches and putative binding sites (protein structure and surfaces) can be visualized interactively online. The website can be accessed at http://catsid.llnl.gov. PMID:23680785

  2. 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.

  3. Get Beyond Limits: From Colloidal Tectonics Concept to the Engineering of Eco-Friendly Catalytic Systems

    Directory of Open Access Journals (Sweden)

    Loïc Leclercq

    2018-05-01

    Full Text Available The interactions between two or more molecules or colloidal particles can be used to obtain a variety of self-assembled systems called supramolecules or supracolloids. There is a clear, but neglected, convergence between these two fields. Indeed, the packing of molecules into colloidal or supracolloidal particles emerges as a smart solution to build an infinite variety of reversible systems with predictable properties. In this respect, the molecular building blocks are called “tectons” whereas “colloidal tectonics” describes the spontaneous formation of (supracolloidal structures using tectonic subunits. As a consequence, a bottom-up edification is allowed from tectons into (supracolloidal particles with higher degrees of organization (Graphical Abstract. These (supracolloidal systems can be very useful to obtain catalysts with tunable amphiphilic properties. In this perspective, an overview of colloidal tectonics concept is presented as well as its use for the design of new, smart, and flexible catalytic systems. Finally, the advantages of these catalytic devices are discussed and the perspective of future developments is addressed especially in the context of “green chemistry.”

  4. 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

  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. Human acid β-glucosidase: isolation and amino acid sequence of a peptide containing the catalytic site

    International Nuclear Information System (INIS)

    Dinur, T.; Osiecki, K.M.; Legler, G.; Gatt, S.; Desnick, R.J.; Grabowski, G.A.

    1986-01-01

    Human acid β-glucosidase (D-glucosyl-N-acylsphingosine glucohydrolase, EC 3.2.1.45) cleaves the glucosidic bonds of glucosylceramide and synthetic β-glucosides. The deficient activity of this hydrolase is the enzymatic defect in the subtypes and variants of Gaucher disease, the most prevalent lysosomal storage disease. To isolate and characterize the catalytic site of the normal enzyme, brominated 3 H-labeled conduritol B epoxide ( 3 H-Br-CBE), which inhibits the enzyme by binding covalently to this site, was used as an affinity label. Under optimal conditions 1 mol of 3 H-Br-CBE bound to 1 mol of pure enzyme protein, indicating the presence of a single catalytic site per enzyme subunit. After V 8 protease digestion of the 3 H-Br-CBE-labeled homogeneous enzyme, three radiolabeled peptides, designated peptide A, B, or C, were resolved by reverse-phase HPLC. The partial amino acid sequence (37 residues) of peptide A (M/sub r/, 5000) was determined. The sequence of this peptide, which contained the catalytic site, had exact homology to the sequence near the carboxyl terminus of the protein, as predicted from the nucleotide sequence of the full-length cDNA encoding acid β-glucosidase

  7. Electrophysiology and Beyond: Multiple roles of Na+ channel β subunits in development and disease

    Science.gov (United States)

    Patino, Gustavo A.; Isom, Lori L.

    2010-01-01

    Voltage-gated Na+ channel (VGSC) β subunits are not “auxiliary.” These multifunctional molecules not only modulate Na+ current (INa), but also function as cell adhesion molecules (CAMs) – playing roles in aggregation, migration, invasion, neurite outgrowth, and axonal fasciculation. β subunits are integral members of VGSC signaling complexes at nodes of Ranvier, axon initial segments, and cardiac intercalated disks, regulating action potential propagation through critical intermolecular and cell-cell communication events. At least in vitro, many β subunit cell adhesive functions occur both in the presence and absence of pore-forming VGSC α subunits, and in vivo β subunits are expressed in excitable as well as non-excitable cells, thus β subunits may play important functional roles on their own, in the absence of α subunits. VGSC β1 subunits are essential for life and appear to be especially important during brain development. Mutations in β subunit genes result in a variety of human neurological and cardiovascular diseases. Moreover, some cancer cells exhibit alterations in β subunit expression during metastasis. In short, these proteins, originally thought of as merely accessory to α subunits, are critical players in their own right in human health and disease. Here we discuss the role of VGSC β subunits in the nervous system. PMID:20600605

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

    Directory of Open Access Journals (Sweden)

    Yu-Tung Chien

    2013-01-01

    Full Text Available 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 results show that catalytic residues have distinct structural features and context. Their neighboring residues, whether sequence or structure neighbors within specific range, are usually structurally more rigid than those of noncatalytic residues. The structural context feature is combined with support vector machine to identify catalytic residues from enzyme structure. The prediction results are better or comparable to those of recent structure-based prediction methods.

  9. Effect of inlet cone pipe angle in catalytic converter

    Science.gov (United States)

    Amira Zainal, Nurul; Farhain Azmi, Ezzatul; Arifin Samad, Mohd

    2018-03-01

    The catalytic converter shows significant consequence to improve the performance of the vehicle start from it launched into production. Nowadays, the geometric design of the catalytic converter has become critical to avoid the behavior of backpressure in the exhaust system. The backpressure essentially reduced the performance of vehicles and increased the fuel consumption gradually. Consequently, this study aims to design various models of catalytic converter and optimize the volume of fluid flow inside the catalytic converter by changing the inlet cone pipe angles. Three different geometry angles of the inlet cone pipe of the catalytic converter were assessed. The model is simulated in Solidworks software to determine the optimum geometric design of the catalytic converter. The result showed that by decreasing the divergence angle of inlet cone pipe will upsurge the performance of the catalytic converter.

  10. Architecture of the large subunit of the mammalian mitochondrial ribosome.

    Science.gov (United States)

    Greber, Basil J; Boehringer, Daniel; Leitner, Alexander; Bieri, Philipp; Voigts-Hoffmann, Felix; Erzberger, Jan P; Leibundgut, Marc; Aebersold, Ruedi; Ban, Nenad

    2014-01-23

    Mitochondrial ribosomes synthesize a number of highly hydrophobic proteins encoded on the genome of mitochondria, the organelles in eukaryotic cells that are responsible for energy conversion by oxidative phosphorylation. The ribosomes in mammalian mitochondria have undergone massive structural changes throughout their evolution, including ribosomal RNA shortening and acquisition of mitochondria-specific ribosomal proteins. Here we present the three-dimensional structure of the 39S large subunit of the porcine mitochondrial ribosome determined by cryo-electron microscopy at 4.9 Å resolution. The structure, combined with data from chemical crosslinking and mass spectrometry experiments, reveals the unique features of the 39S subunit at near-atomic resolution and provides detailed insight into the architecture of the polypeptide exit site. This region of the mitochondrial ribosome has been considerably remodelled compared to its bacterial counterpart, providing a specialized platform for the synthesis and membrane insertion of the highly hydrophobic protein components of the respiratory chain.

  11. Testing experimental subunit furunculosis vaccines for rainbow trout

    DEFF Research Database (Denmark)

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

    2016-01-01

    Aeromonas salmonicida subsp. salmonicida (AS) is the etiological agent of typical furunculosis in salmonid fish. The disease causes bacterial septicemia and is a major fish health problem in salmonid aquaculture worldwide, inducing high morbidity and mortality. In this study we vaccinated rainbow...... 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...... response against AS. Fourteen proteins were prepared in 3 different experimental subunit vaccine combinations and used to vaccinate rainbow trout by intraperitoneal (i.p.) injection. We tested the proteins for their ability to elicit antibody production and protection. Thus, fish were exposed to virulent...

  12. 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.

  13. Zeolitic catalytic conversion of alcohols to hydrocarbons

    Science.gov (United States)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2018-04-10

    A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

  14. Method to produce catalytically active nanocomposite coatings

    Science.gov (United States)

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2016-02-09

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  15. Enantioselective catalytic fluorinative aza-semipinacol rearrangement.

    Science.gov (United States)

    Romanov-Michailidis, Fedor; Pupier, Marion; Besnard, Céline; Bürgi, Thomas; Alexakis, Alexandre

    2014-10-03

    An efficient and highly stereoselective fluorinative aza-semipinacol rearrangement is described. The catalytic reaction requires use of Selectfluor in combination with the chiral, enantiopure phosphate anion derived from acid L3. Under optimized conditions, cyclopropylamines A were transformed into β-fluoro cyclobutylimines B in good yields and high levels of diastereo- and enantiocontrol. Furthermore, the optically active cyclobutylimines were reduced diastereoselectively with L-Selectride in the corresponding fluorinated amines C, compounds of significant interest in the pharmacological industry.

  16. Zeolitic catalytic conversion of alochols to hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2017-01-03

    A method for converting an alcohol to a hydrocarbon, the method comprising contacting said alcohol with a metal-loaded zeolite catalyst at a temperature of at least 100.degree. C. and up to 550.degree. C., wherein said alcohol can be produced by a fermentation process, said metal is a positively-charged metal ion, and said metal-loaded zeolite catalyst is catalytically active for converting said alcohol to said hydrocarbon.

  17. 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

  18. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.; Zeitoon, B.M.

    1995-01-01

    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

  19. Method to produce catalytically active nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Ali; Eryilmaz, Osman Levent; Urgen, Mustafa; Kazmanli, Kursat

    2017-12-19

    A nanocomposite coating and method of making and using the coating. The nanocomposite coating is disposed on a base material, such as a metal or ceramic; and the nanocomposite consists essentially of a matrix of an alloy selected from the group of Cu, Ni, Pd, Pt and Re which are catalytically active for cracking of carbon bonds in oils and greases and a grain structure selected from the group of borides, carbides and nitrides.

  20. ASIC subunit ratio and differential surface trafficking in the brain.

    Science.gov (United States)

    Wu, Junjun; Xu, Yuanyuan; Jiang, Yu-Qing; Xu, Jiangping; Hu, Youjia; Zha, Xiang-ming

    2016-01-08

    Acid-sensing ion channels (ASICs) are key mediators of acidosis-induced responses in neurons. However, little is known about the relative abundance of different ASIC subunits in the brain. Such data are fundamental for interpreting the relative contribution of ASIC1a homomers and 1a/2 heteromers to acid signaling, and essential for designing therapeutic interventions to target these channels. We used a simple biochemical approach and semi-quantitatively determined the molar ratio of ASIC1a and 2 subunits in mouse brain. Further, we investigated differential surface trafficking of ASIC1a, ASIC2a, and ASIC2b. ASIC1a subunits outnumber the sum of ASIC2a and ASIC2b. There is a region-specific variation in ASIC2a and 2b expression, with cerebellum and striatum expressing predominantly 2b and 2a, respectively. Further, we performed surface biotinylation and found that surface ASIC1a and ASIC2a ratio correlates with their total expression. In contrast, ASIC2b exhibits little surface presence in the brain. This result is consistent with increased co-localization of ASIC2b with an ER marker in 3T3 cells. Our data are the first semi-quantitative determination of relative subunit ratio of various ASICs in the brain. The differential surface trafficking of ASICs suggests that the main functional ASICs in the brain are ASIC1a homomers and 1a/2a heteromers. This finding provides important insights into the relative contribution of various ASIC complexes to acid signaling in neurons.

  1. Catalytic hydrogen recombination for nuclear containments

    International Nuclear Information System (INIS)

    Koroll, G.W.; Lau, D.W.P.; Dewit, W.A.; Graham, W.R.C.

    1994-01-01

    Catalytic recombiners appear to be a credible option for hydrogen mitigation in nuclear containments. The passive operation, versatility and ease of back fitting are appealing for existing stations and new designs. Recently, a generation of wet-proofed catalyst materials have been developed at AECL which are highly specific to H 2 -O 2 , are active at ambient temperatures and are being evaluated for containment applications. Two types of catalytic recombiners were evaluated for hydrogen removal in containments based on the AECL catalyst. The first is a catalytic combustor for application in existing air streams such as provided by fans or ventilation systems. The second is an autocatalytic recombiner which uses the enthalpy of reaction to produce natural convective flow over the catalyst elements. Intermediate-scale results obtained in 6 m 3 and 10 m 3 spherical and cylindrical vessels are given to demonstrate self-starting limits, operating limits, removal capacity, scaling parameters, flow resistance, mixing behaviour in the vicinity of an operating recombiner and sensitivity to poisoning, fouling and radiation. (author). 13 refs., 10 figs

  2. Electrochemical catalytic treatment of phenol wastewater

    International Nuclear Information System (INIS)

    Ma Hongzhu; Zhang Xinhai; Ma Qingliang; Wang Bo

    2009-01-01

    The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

  3. 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.

  4. Vapor-Driven Propulsion of Catalytic Micromotors

    Science.gov (United States)

    Dong, Renfeng; Li, Jinxing; Rozen, Isaac; Ezhilan, Barath; Xu, Tailin; Christianson, Caleb; Gao, Wei; Saintillan, David; Ren, Biye; Wang, Joseph

    2015-08-01

    Chemically-powered micromotors offer exciting opportunities in diverse fields, including therapeutic delivery, environmental remediation, and nanoscale manufacturing. However, these nanovehicles require direct addition of high concentration of chemical fuel to the motor solution for their propulsion. We report the efficient vapor-powered propulsion of catalytic micromotors without direct addition of fuel to the micromotor solution. Diffusion of hydrazine vapor from the surrounding atmosphere into the sample solution is instead used to trigger rapid movement of iridium-gold Janus microsphere motors. Such operation creates a new type of remotely-triggered and powered catalytic micro/nanomotors that are responsive to their surrounding environment. This new propulsion mechanism is accompanied by unique phenomena, such as the distinct off-on response to the presence of fuel in the surrounding atmosphere, and spatio-temporal dependence of the motor speed borne out of the concentration gradient evolution within the motor solution. The relationship between the motor speed and the variables affecting the fuel concentration distribution is examined using a theoretical model for hydrazine transport, which is in turn used to explain the observed phenomena. The vapor-powered catalytic micro/nanomotors offer new opportunities in gas sensing, threat detection, and environmental monitoring, and open the door for a new class of environmentally-triggered micromotors.

  5. 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.

  6. Antibody proteases: induction of catalytic response.

    Science.gov (United States)

    Gabibov, A G; Friboulet, A; Thomas, D; Demin, A V; Ponomarenko, N A; Vorobiev, I I; Pillet, D; Paon, M; Alexandrova, E S; Telegin, G B; Reshetnyak, A V; Grigorieva, O V; Gnuchev, N V; Malishkin, K A; Genkin, D D

    2002-10-01

    Most of the data accumulated throughout the years on investigation of catalytic antibodies indicate that their production increases on the background of autoimmune abnormalities. The different approaches to induction of catalytic response toward recombinant gp120 HIV-1 surface protein in mice with various autoimmune pathologies are described. The peptidylphosphonate conjugate containing structural part of gp120 molecule is used for reactive immunization of NZB/NZW F1, MRL, and SJL mice. The specific modification of heavy and light chains of mouse autoantibodies with Val-Ala-Glu-Glu-Glu-Val-PO(OPh)2 reactive peptide was demonstrated. Increased proteolytic activity of polyclonal antibodies in SJL mice encouraged us to investigate the production of antigen-specific catalytic antibodies on the background of induced experimental autoimmune encephalomyelitis (EAE). The immunization of autoimmune-prone mice with the engineered fusions containing the fragments of gp120 and encephalitogenic epitope of myelin basic protein (MBP(89-104)) was made. The proteolytic activity of polyclonal antibodies isolated from the sera of autoimmune mice immunized by the described antigen was shown. Specific immune response of SJL mice to these antigens was characterized. Polyclonal antibodies purified from sera of the immunized animals revealed proteolytic activity. The antiidiotypic approach to raise the specific proteolytic antibody as an "internal image" of protease is described. The "second order" monoclonal antibodies toward subtilisin Carlsberg revealed pronounced proteolytic activity.

  7. Electrochemical catalytic treatment of phenol wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Ma Hongzhu, E-mail: hzmachem@snnu.edu.cn [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Zhang Xinhai [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China); Ma Qingliang [Department of Applied Physics, College of Sciences, Taiyuan University of Technology, 030024 Taiyuan (China); Wang Bo [Institute of Energy Chemistry, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an 710062 (China)

    2009-06-15

    The slurry bed catalytic treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. In this paper, the electrochemical oxidation of phenol in synthetic wastewater catalyzed by ferric sulfate and potassium permanganate adsorbed onto active bentonite in slurry bed electrolytic reactor with graphite electrode has been investigated. In order to determine the optimum operating condition, the orthogonal experiments were devised and the results revealed that the system of ferric sulfate, potassium permanganate and active bentonite showed a high catalytic efficiency on the process of electrochemical oxidation phenol in initial pH 5. When the initial concentration of phenol was 0.52 g/L (the initial COD 1214 mg/L), up to 99% chemical oxygen demand (COD) removal was obtained in 40 min. According to the experimental results, a possible mechanism of catalytic degradation of phenol was proposed. Environmental estimation was also done and the results showed that the treated wastewater have little impact on plant growth and could totally be applied to irrigation.

  8. Radioimmunoassay of TSH subunits in thyroid diseases and endocrine opthalmopahty

    International Nuclear Information System (INIS)

    Eder, W.

    1982-01-01

    Highly sensitive radioimmunoassays of hTSH sub-units were developed. The hormone preparations were labelled with 125-iodine according to a modified chloramine -T method, and purified by chromatography using biogel P6 and P60. Rabbit antisera were used as antibodies. Separation of the antibody-bound and of the free antigens was carried out via the double antibody method. The antiserum required for this purpose was obtained from a goat. The sensitivity of the assay was influenced by changing the protein content of the buffer, the incubation volume, the tracer amounts, the incubation time and the incubation temperature. For hTSH-α, the lowest detectable limit was found to be 50 pg/ml, for hTSH-#betta# 20 pg/ml. Thus, the sub-units could be determined for 98% of the patients under review. The #betta#-TSH radioimmunoassay is largely specific, TSH cross-reacts to a degree of 5%. The computerized evoluation was carried out by means of Spline approximation using the Siemens 4004 computer. Precision and accurateness are in compliance with generally accpted criteria. The serum levels of α and #betta# sub-units showed no discordancy with regard to TSH. In all groups of patients examined, the levels of the hormone-specific #betta#-chain were found to be exclusively dependent upon the actual thyroid activity. (orig.) [de

  9. Downregulation of SWI/SNF chromatin remodeling factor subunits modulates cisplatin cytotoxicity

    International Nuclear Information System (INIS)

    Kothandapani, Anbarasi; Gopalakrishnan, Kathirvel; Kahali, Bhaskar; Reisman, David; Patrick, Steve M.

    2012-01-01

    Chromatin remodeling complex SWI/SNF plays important roles in many cellular processes including transcription, proliferation, differentiation and DNA repair. In this report, we investigated the role of SWI/SNF catalytic subunits Brg1 and Brm in the cellular response to cisplatin in lung cancer and head/neck cancer cells. Stable knockdown of Brg1 and Brm enhanced cellular sensitivity to cisplatin. Repair kinetics of cisplatin DNA adducts revealed that downregulation of Brg1 and Brm impeded the repair of both intrastrand adducts and interstrand crosslinks (ICLs). Cisplatin ICL-induced DNA double strand break repair was also decreased in Brg1 and Brm depleted cells. Altered checkpoint activation with enhanced apoptosis as well as impaired chromatin relaxation was observed in Brg1 and Brm deficient cells. Downregulation of Brg1 and Brm did not affect the recruitment of DNA damage recognition factor XPC to cisplatin DNA lesions, but affected ERCC1 recruitment, which is involved in the later stages of DNA repair. Based on these results, we propose that SWI/SNF chromatin remodeling complex modulates cisplatin cytotoxicity by facilitating efficient repair of the cisplatin DNA lesions. -- Highlights: ► Stable knockdown of Brg1 and Brm enhances cellular sensitivity to cisplatin. ► Downregulation of Brg1 and Brm impedes the repair of cisplatin intrastrand adducts and interstrand crosslinks. ► Brg1 and Brm deficiency results in impaired chromatin relaxation, altered checkpoint activation as well as enhanced apoptosis. ► Downregulation of Brg1 and Brm affects recruitment of ERCC1, but not XPC to cisplatin DNA lesions.

  10. The cytochrome oxidase subunit I and subunit III genes in Oenothera mitochondria are transcribed from identical promoter sequences

    Science.gov (United States)

    Hiesel, Rudolf; Schobel, Werner; Schuster, Wolfgang; Brennicke, Axel

    1987-01-01

    Two loci encoding subunit III of the cytochrome oxidase (COX) in Oenothera mitochondria have been identified from a cDNA library of mitochondrial transcripts. A 657-bp sequence block upstream from the open reading frame is also present in the two copies of the COX subunit I gene and is presumably involved in homologous sequence rearrangement. The proximal points of sequence rearrangements are located 3 bp upstream from the COX I and 1139 bp upstream from the COX III initiation codons. The 5'-termini of both COX I and COX III mRNAs have been mapped in this common sequence confining the promoter region for the Oenothera mitochondrial COX I and COX III genes to the homologous sequence block. ImagesFig. 5. PMID:15981332

  11. 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.

  12. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion

    International Nuclear Information System (INIS)

    Pozan, Gulin Selda

    2012-01-01

    Highlights: ► α-Al 2 O 3 , obtained from Bohmite, as a support for enhancing of the activity. ► The support material for catalytic oxidation. ► The manganese state and oxygen species effect on the catalytic combustion reaction. - Abstract: The aim of this work was to study combustion of toluene (1000 ppm) over MnO 2 modified with different supports. α-Al 2 O 3 and γ-Al 2 O 3 obtained from Boehmite, γ-Al 2 O 3 (commercial), SiO 2 , TiO 2 and ZrO 2 were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO 2 was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO 2 /α-Al 2 O 3 (B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289 °C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity.

  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. 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

  15. Studies on the Catalytic Properties of Partially Purified Alkaline Proteases from Some Selected Microorganisms

    Directory of Open Access Journals (Sweden)

    Titilayo Olufunke Femi-Ola

    2012-09-01

    Full Text Available Aims: The research was done to study the conditions enhancing catalytic activities of alkaline proteases from Vibro sp., Lactobacillus brevis, Zymomonas sp., Athrobacter sp., Corynebacterium sp. and Bacillus subtilis.Methodology and Results: The proteolytic enzymes were purified in 2-step procedures involving ammonium sulphate precipitation and sephadex G-150 gel permeation chromatography. The upper and lower limits for the specific activities of proteases from the selected microorganisms were estimated at 20.63 and 47.51 units/mg protein with Zymomonas protease having the highest specific activity towards casein as its substrate and purification fold of 3.46, while that ofLactobacillus brevis protease was 8.06. The native molecular weights of these active proteins ranged from 30.4 to 45.7 kDa with Athrobacter sp. protease having the highest weight for its subunits. The proteolytic enzymes had optimum pH range of 8 to 10 and temperature range of 50 to 62 ºC accounting for the percentage relative activity range of 75 to 94% and 71 to 84 % respectively. The activities of Lactobacillus brevis and Bacillus subtilis proteases were maximum at pH 9 and 10 respectively. Lactobacillus brevis protease activity was maximum at temperature of 62 ºC, while beyond this value, a general thermal instability of these active proteins was observed. At above 70 ºC, the catalytic activities of Corynebacterium sp., Vibrio sp., Zymomonas sp. and Arthrobacter sp. proteases were progressively reduced over a period of 120 min of incubation, while Bacillus subtlis and Lactobacillus brevis proteases were relatively stable. Effect of metal ions was investigated on the catalytic activity of protease from the microorganisms. Lactobacillus brevis,Zymomonas sp., Arthrobacter sp., Corynebacterium sp. and Bacillus subtilis protease activities were strongly activated by metal ions such as Ca+2 and Mg+2. Enzyme activities were inhibited strongly by Cu2+ and Hg2+ but were not

  16. 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. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Catalytic cracking models developed for predictive control purposes

    Directory of Open Access Journals (Sweden)

    Dag Ljungqvist

    1993-04-01

    Full Text Available The paper deals with state-space modeling issues in the context of model-predictive control, with application to catalytic cracking. Emphasis is placed on model establishment, verification and online adjustment. Both the Fluid Catalytic Cracking (FCC and the Residual Catalytic Cracking (RCC units are discussed. Catalytic cracking units involve complex interactive processes which are difficult to operate and control in an economically optimal way. The strong nonlinearities of the FCC process mean that the control calculation should be based on a nonlinear model with the relevant constraints included. However, the model can be simple compared to the complexity of the catalytic cracking plant. Model validity is ensured by a robust online model adjustment strategy. Model-predictive control schemes based on linear convolution models have been successfully applied to the supervisory dynamic control of catalytic cracking units, and the control can be further improved by the SSPC scheme.

  18. Protein structure based prediction of catalytic residues.

    Science.gov (United States)

    Fajardo, J Eduardo; Fiser, Andras

    2013-02-22

    Worldwide structural genomics projects continue to release new protein structures at an unprecedented pace, so far nearly 6000, but only about 60% of these proteins have any sort of functional annotation. We explored a range of features that can be used for the prediction of functional residues given a known three-dimensional structure. These features include various centrality measures of nodes in graphs of interacting residues: closeness, betweenness and page-rank centrality. We also analyzed the distance of functional amino acids to the general center of mass (GCM) of the structure, relative solvent accessibility (RSA), and the use of relative entropy as a measure of sequence conservation. From the selected features, neural networks were trained to identify catalytic residues. We found that using distance to the GCM together with amino acid type provide a good discriminant function, when combined independently with sequence conservation. Using an independent test set of 29 annotated protein structures, the method returned 411 of the initial 9262 residues as the most likely to be involved in function. The output 411 residues contain 70 of the annotated 111 catalytic residues. This represents an approximately 14-fold enrichment of catalytic residues on the entire input set (corresponding to a sensitivity of 63% and a precision of 17%), a performance competitive with that of other state-of-the-art methods. We found that several of the graph based measures utilize the same underlying feature of protein structures, which can be simply and more effectively captured with the distance to GCM definition. This also has the added the advantage of simplicity and easy implementation. Meanwhile sequence conservation remains by far the most influential feature in identifying functional residues. We also found that due the rapid changes in size and composition of sequence databases, conservation calculations must be recalibrated for specific reference databases.

  19. Catalytic oxidation of soot over alkaline niobates

    International Nuclear Information System (INIS)

    Pecchi, G.; Cabrera, B.; Buljan, A.; Delgado, E.J.; Gordon, A.L.; Jimenez, R.

    2013-01-01

    Highlights: ► No previous reported studies about alkaline niobates as catalysts for soot oxidation. ► NaNbO 3 and KNbO 3 perovskite-type oxides show lower activation energy than other lanthanoid perovskite-type oxides. ► The alkaline niobate does not show deactivation by metal loss. - Abstract: The lack of studies in the current literature about the assessment of alkaline niobates as catalysts for soot oxidation has motivated this research. In this study, the synthesis, characterization and assessment of alkaline metal niobates as catalysts for soot combustion are reported. The solids MNbO 3 (M = Li, Na, K, Rb) are synthesized by a citrate method, calcined at 450 °C, 550 °C, 650 °C, 750 °C, and characterized by AAS, N 2 adsorption, XRD, O 2 -TPD, FTIR and SEM. All the alkaline niobates show catalytic activity for soot combustion, and the activity depends basically on the nature of the alkaline metal and the calcination temperature. The highest catalytic activity, expressed as the temperature at which combustion of carbon black occurs at the maximum rate, is shown by KNbO 3 calcined at 650 °C. At this calcination temperature, the catalytic activity follows an order dependent on the atomic number, namely: KNbO 3 > NaNbO 3 > LiNbO 3 . The RbNbO 3 solid do not follow this trend presumably due to the perovskite structure was not reached. The highest catalytic activity shown by of KNbO 3 , despite the lower apparent activation energy of NaNbO 3 , stress the importance of the metal nature and suggests the hypothesis that K + ions are the active sites for soot combustion. It must be pointed out that alkaline niobate subjected to consecutive soot combustion cycles does not show deactivation by metal loss, due to the stabilization of the alkaline metal inside the perovskite structure.

  20. Tritium stripping by a catalytic exchange stripper

    International Nuclear Information System (INIS)

    Heung, L.K.; Gibson, G.W.; Ortman, M.S.

    1991-01-01

    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

  1. Plasma-catalytic reforming of liquid hydrocarbons

    International Nuclear Information System (INIS)

    Nedybaliuk, O.A.; Chernyak, V.Ya; Kolgan, V.V.; Iukhymenko, V.V.; Solomenko, O.V.; Fedirchyk, I.I.; Martysh, E.V.; Demchina, V.P.; Klochok, N.V.; Dragnev, S.V.

    2015-01-01

    The series of experiments studying the plasma-catalytic reforming of liquid hydrocarbons was carried out. The dynamic plasma-liquid system based on a low-power rotating gliding arc with solid electrodes was used for the investigation of liquid hydrocarbons reforming process. Conversion was done via partial oxidation. A part of oxidant flow was activated by the discharge. Synthesis-gas composition was analysed by means of mass-spectrometry and gas-chromatography. A standard boiler, which operates on natural gas and LPG, was used for the burning of synthesis-gas

  2. Methane combustion in catalytic premixed burners

    International Nuclear Information System (INIS)

    Cerri, I.; Saracco, G.; Specchia, V.

    1999-01-01

    Catalytic premixed burners for domestic boiler applications were developed with the aim of achieving a power modularity from 10 to 100% and pollutant emissions limited to NO x 2 , where the combustion took place entirely inside the burner heating it to incandescence and allowing a decrease in the flame temperature and NO x emissions. Such results were confirmed through further tests carried out in a commercial industrial-scale boiler equipped with the conical panels. All the results, by varying the excess air and the heat power employed, are presented and discussed [it

  3. Direct catalytic hydrothermal liquefaction of spirulina to biofuels with hydrogen

    Science.gov (United States)

    Zeng, Qin; Liao, Hansheng; Zhou, Shiqin; Li, Qiuping; Wang, Lu; Yu, Zhihao; Jing, Li

    2018-01-01

    We report herein on acquiring biofuels from direct catalytic hydrothermal liquefaction of spirulina. The component of bio-oil from direct catalytic hydrothermal liquefaction was similar to that from two independent processes (including liquefaction and upgrading of biocrude). However, one step process has higher carbon recovery, due to the less loss of carbons. It was demonstrated that the yield and HHV of bio-oil from direct catalytic algae with hydrothermal condition is higher than that from two independent processes.

  4. 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 differ...... different approximations are investigated: site, mean-field, and quasichemical approximations. The obtained results are compared to accurate Monte Carlo numbers. In the end, we apply the approximations to a real catalytic reaction, namely, ammonia synthesis....

  5. A study on naphtha catalytic reforming reactor simulation and analysis.

    Science.gov (United States)

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-06-01

    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.

  6. A study on naphtha catalytic reforming reactor simulation and analysis

    OpenAIRE

    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 uni...

  7. Molecular cloning of the human casein kinase II α subunit

    International Nuclear Information System (INIS)

    Meisner, H.; Heller-Harrison, R.; Buxton, J.; Czech, M.P.

    1989-01-01

    A human cDNA encoding the α subunit of casein kinase II and a partial cDNA encoding the rat homologue were isolated by using a Drosophila casein kinase II cDNA probe. The 2.2-kb human cDNA contains a 1.2-kb open reading frame, 150 nucleotides of 5' leader, and 850 nucleotides of 3' noncoding region. Except for the first 7 deduced amino acids that are missing in the rat cDNA, the 328 amino acids beginning with the amino terminus are identical between human and rat. The Drosophila enzyme sequence is 90% identical with the human casein kinase II sequence, and there is only a single amino acid difference between the published partial bovine sequence and the human sequence. In addition, the C-terminus of the human cDNA has an extra 53 amino acids not present in Drosophila. Northern analysis of rat and human RNA showed predominant bands of 5.5, 3.1, and 1.8 kb. In rat tissues, brain and spleen had the highest levels of casein kinase II α subunit specific RNA, while skeletal muscle showed the lowest. Southern analysis of human cultured cell and tissue genomic DNA using the full-length cDNA probe revealed two bands with restriction enzymes that have no recognition sites within the cDNA and three to six bands with enzymes having single internal sites. These results are consistent with the possibility that two genes encode the α subunits

  8. Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, R.M.B. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia]|[Universidade Nova de Lisboa, Oeiras (Portugal). Instituto de Tecnologia Quimica e Biologica; Franco, E.; Teixeira, A.R.N. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia

    1996-08-15

    The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of {sup 35}S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author).

  9. Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

    International Nuclear Information System (INIS)

    Ferreira, R.M.B.; Universidade Nova de Lisboa, Oeiras; Franco, E.; Teixeira, A.R.N.

    1996-01-01

    The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of 35 S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author)

  10. Flexible Connectors between Capsomer Subunits that Regulate Capsid Assembly.

    Science.gov (United States)

    Hasek, Mary L; Maurer, Joshua B; Hendrix, Roger W; Duda, Robert L

    2017-08-04

    Viruses build icosahedral capsids of specific size and shape by regulating the spatial arrangement of the hexameric and pentameric protein capsomers in the growing shell during assembly. In the T=7 capsids of Escherichia coli bacteriophage HK97 and other phages, 60 capsomers are hexons, while the rest are pentons that are correctly positioned during assembly. Assembly of the HK97 capsid to the correct size and shape has been shown to depend on specific ionic contacts between capsomers. We now describe additional ionic interactions within capsomers that also regulate assembly. Each is between the long hairpin, the "E-loop," that extends from one subunit to the adjacent subunit within the same capsomer. Glutamate E153 on the E-loop and arginine R210 on the adjacent subunit's backbone alpha-helix form salt bridges in hexamers and pentamers. Mutations that disrupt these salt bridges were lethal for virus production, because the mutant proteins assembled into tubes or sheets instead of capsids. X-ray structures show that the E153-R210 links are flexible and maintained during maturation despite radical changes in capsomer shape. The E153-R210 links appear to form early in assembly to enable capsomers to make programmed changes in their shape during assembly. The links also prevent flattening of capsomers and premature maturation. Mutant phenotypes and modeling support an assembly model in which flexible E153-R210 links mediate capsomer shape changes that control where pentons are placed to create normal-sized capsids. The E-loop may be conserved in other systems in order to play similar roles in regulating assembly. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Effect of support on the catalytic activity of manganese oxide catalyts for toluene combustion.

    Science.gov (United States)

    Pozan, Gulin Selda

    2012-06-30

    The aim of this work was to study combustion of toluene (1000ppm) over MnO(2) modified with different supports. α-Al(2)O(3) and γ-Al(2)O(3) obtained from Boehmite, γ-Al(2)O(3) (commercial), SiO(2), TiO(2) and ZrO(2) were used as commercial support materials. In view of potential interest of this process, the influence of support material on the catalytic performance was discussed. The deposition of 9.5MnO(2) was performed by impregnation over support. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed reduction and oxidation (TPR/TPO) and thermogravimetric analysis (TGA). The catalytic tests were carried out at atmospheric pressure in a fixed-bed flow reactor. 9.5MnO(2)/α-Al(2)O(3)(B) (synthesized from Boehmite) catalyst exhibits the highest catalytic activity, over which the toluene conversion was up to 90% at a temperature of 289°C. Considering all the characterization and reaction data reported in this study, it was concluded that the manganese state and oxygen species played an important role in the catalytic activity. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. Catalytic membrane in reduction of aqueous nitrates: operational principles and catalytic performance

    NARCIS (Netherlands)

    Ilinitch, O.M.; Cuperus, F.P.; Nosova, L.V.; Gribov, E.N.

    2000-01-01

    The catalytic membrane with palladium-copper active component supported over the macroporous ceramic membrane, and a series of γ-Al 2O 3 supported Pd-Cu catalysts were prepared and investigated. In reduction of nitrate ions by hydrogen in water at ambient temperature, pronounced internal diffusion

  13. Non-thermal plasmas for non-catalytic and catalytic VOC abatement

    International Nuclear Information System (INIS)

    Vandenbroucke, Arne M.; Morent, Rino; De Geyter, Nathalie; Leys, Christophe

    2011-01-01

    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.

  14. Sex Hormone Receptor Expression in the Human Vocal Fold Subunits.

    Science.gov (United States)

    Kirgezen, Tolga; Sunter, Ahmet Volkan; Yigit, Ozgur; Huq, Gulben Erdem

    2017-07-01

    The study aimed to evaluate the existence of sex hormone receptors in the subunits of vocal fold. This is a cadaver study. The androgen, estrogen, and progesterone receptors were examined in the epithelium (EP), superficial layer of the lamina propria (SLP), vocal ligament (VL), and macula flava (MF) of the vocal folds from 42 human cadavers (21 male, 21 female) by immunohistochemical methods. Their staining ratios were scored and statistically compared. The androgen receptor score was significantly higher for the MF than for the EP and SLP (P vocal fold, mostly in the MF and VLs. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  15. Microwave Catalytic Oxidation of Hydrocarbons in Aqueous Solutions

    National Research Council Canada - National Science Library

    Cha, Chang

    2003-01-01

    .... A sufficient amount of experimental work has been completed evaluating the performance of the microwave catalytic oxidation process and determining the effect of different operating parameters...

  16. 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.

  17. N-linked glycans are required on epithelial Na+ channel subunits for maturation and surface expression.

    Science.gov (United States)

    Kashlan, Ossama B; Kinlough, Carol L; Myerburg, Michael M; Shi, Shujie; Chen, Jingxin; Blobner, Brandon M; Buck, Teresa M; Brodsky, Jeffrey L; Hughey, Rebecca P; Kleyman, Thomas R

    2018-03-01

    Epithelial Na + channel (ENaC) subunits undergo N-linked glycosylation in the endoplasmic reticulum where they assemble into an αβγ complex. Six, 13, and 5 consensus sites (Asn-X-Ser/Thr) for N-glycosylation reside in the extracellular domains of the mouse α-, β-, and γ-subunits, respectively. Because the importance of ENaC N-linked glycans has not been fully addressed, we examined the effect of preventing N-glycosylation of specific subunits on channel function, expression, maturation, and folding. Heterologous expression in Xenopus oocytes or Fischer rat thyroid cells with αβγ-ENaC lacking N-linked glycans on a single subunit reduced ENaC activity as well as the inhibitory response to extracellular Na + . The lack of N-linked glycans on the β-subunit also precluded channel activation by trypsin. However, channel activation by shear stress was N-linked glycan independent, regardless of which subunit was modified. We also discovered that the lack of N-linked glycans on any one subunit reduced the total and surface levels of cognate subunits. The lack of N-linked glycans on the β-subunit had the largest effect on total levels, with the lack of N-linked glycans on the γ- and α-subunits having intermediate and modest effects, respectively. Finally, channels with wild-type β-subunits were more sensitive to limited trypsin proteolysis than channels lacking N-linked glycans on the β-subunit. Our results indicate that N-linked glycans on each subunit are required for proper folding, maturation, surface expression, and function of the channel.

  18. 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.

  19. New separation technique. Catalytically functionated separation membrane

    Energy Technology Data Exchange (ETDEWEB)

    Urgami, Tadashi [Kansai Univ., Osaka (Japan)

    1989-02-01

    This report introduces research examples, showing the fundamental principle of the membrane by separating the catalytically functionated separation membrane into enzyme fixing separation membrane, polymerized metal complex separation membrane and polymer catalyst separation membrane. This membrane can achieve both functions of separation and catalytic reaction simultaneously and has sufficient possibility to combine powerful functions. Enzyme fixing separation membrane is prepared by carrier combination method, bridging method or covering method and the enzyme fixing method with polymerized complex in which enzyme is controlled to prevent the activity lowering as much as possible and enzyme is fixed from an aqueous solution into polymer membrane. This membrane is applied to the continuous manufacturing of invert sugar from cane sugar and adsorption and removing of harmful substances from blood by utilizing both micro-capsuled urease and active carbon. Alginic acid-copper (II) complex membrane is used for the polymerized metal complex membrane and polystyrene sulfonate membrane is used for the polymer catalyst separation membrane. 28 refs., 4 figs., 1 tabs.

  20. Study of catalytic phenomena in radiation chemistry

    International Nuclear Information System (INIS)

    Dran, J.C.

    1965-01-01

    Two phenomena have been studied: the action of γ rays from radio-cobalt on the adsorption and catalytic properties of ZnO and NiO in. relationship with the heterogeneous oxidation of CO, and the homogeneous catalysis by OsO 4 of the oxidation of various aqueous phase solutes by the same radiation. The prior irradiation of ZnO and of NiO does not modify their catalytic activity but generally increases the adsorption energy of -the gases CO and O 2 . The influence of the radiations appears to be connected with the presence of traces of water on ZnO and of an excess of oxygen on NiO. Osmium tetroxide which is not degraded by irradiation in acid solution, accelerates the radiolytic oxidation of certain compounds (Te IV , Pt 11 , As 111 ) in the presence of oxygen, as a result of its sensitizing effect on the oxidation by H 2 O 2 . In the case of phosphites on the other hand, OsO 4 has a protecting action under certain conditions of acidity and may suppress entirely the chain reaction which characterizes the oxidation of this solute byγ rays. A general mechanism is proposed for these phenomena. The rate constant for the OsO 4 + HO 2 reaction is calculated to be 5.7 x 10 5 l.mol -1 . sec -1 . (author) [fr

  1. Catalytic hydroprocessing of heavy oil feedstocks

    International Nuclear Information System (INIS)

    Okunev, A G; Parkhomchuk, E V; Lysikov, A I; Parunin, P D; Semeikina, V S; Parmon, V N

    2015-01-01

    A grave problem of modern oil refining industry is continuous deterioration of the produced oil quality, on the one hand, and increase in the demand for motor fuels, on the other hand. This necessitates processing of heavy oil feedstock with high contents of sulfur, nitrogen and metals and the atmospheric residue. This feedstock is converted to light oil products via hydrogenation processes catalyzed by transition metal compounds, first of all, cobalt- or nickel-promoted molybdenum and tungsten compounds. The processing involves desulfurization, denitrogenation and demetallization reactions as well as reactions converting heavy hydrocarbons to lighter fuel components. The review discusses the mechanisms of reactions involved in the heavy feedstock hydroprocessing, the presumed structure and state of the catalytically active components and methods for the formation of supports with the desired texture. Practically used and prospective approaches to catalytic upgrading of heavy oil feedstock as well as examples of industrial processing of bitumen and vacuum residues in the presence of catalysts are briefly discussed. The bibliography includes 140 references

  2. Catalytic hydroprocessing of heavy oil feedstocks

    Science.gov (United States)

    Okunev, A. G.; Parkhomchuk, E. V.; Lysikov, A. I.; Parunin, P. D.; Semeikina, V. S.; Parmon, V. N.

    2015-09-01

    A grave problem of modern oil refining industry is continuous deterioration of the produced oil quality, on the one hand, and increase in the demand for motor fuels, on the other hand. This necessitates processing of heavy oil feedstock with high contents of sulfur, nitrogen and metals and the atmospheric residue. This feedstock is converted to light oil products via hydrogenation processes catalyzed by transition metal compounds, first of all, cobalt- or nickel-promoted molybdenum and tungsten compounds. The processing involves desulfurization, denitrogenation and demetallization reactions as well as reactions converting heavy hydrocarbons to lighter fuel components. The review discusses the mechanisms of reactions involved in the heavy feedstock hydroprocessing, the presumed structure and state of the catalytically active components and methods for the formation of supports with the desired texture. Practically used and prospective approaches to catalytic upgrading of heavy oil feedstock as well as examples of industrial processing of bitumen and vacuum residues in the presence of catalysts are briefly discussed. The bibliography includes 140 references.

  3. 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.

  4. Structured materials for catalytic and sensing applications

    Science.gov (United States)

    Hokenek, Selma

    The optical and chemical properties of the materials used in catalytic and sensing applications directly determine the characteristics of the resultant catalyst or sensor. It is well known that a catalyst needs to have high activity, selectivity, and stability to be viable in an industrial setting. The hydrogenation activity of palladium catalysts is known to be excellent, but the industrial applications are limited by the cost of obtaining catalyst in amounts large enough to make their use economical. As a result, alloying palladium with a cheaper, more widely available metal while maintaining the high catalytic activity seen in monometallic catalysts is, therefore, an attractive option. Similarly, the optical properties of nanoscale materials used for sensing must be attuned to their application. By adjusting the shape and composition of nanoparticles used in such applications, very fine changes can be made to the frequency of light that they absorb most efficiently. The design, synthesis, and characterization of (i) size controlled monometallic palladium nanoparticles for catalytic applications, (ii) nickel-palladium bimetallic nanoparticles and (iii) silver-palladium nanoparticles with applications in drug detection and biosensing through surface plasmon resonance, respectively, will be discussed. The composition, size, and shape of the nanoparticles formed were controlled through the use of wet chemistry techniques. After synthesis, the nanoparticles were analyzed using physical and chemical characterization techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy- Energy-Dispersive Spectrometry (STEM-EDX). The Pd and Ni-Pd nanoparticles were then supported on silica for catalytic testing using mass spectrometry. The optical properties of the Ag-Pd nanoparticles in suspension were further investigated using ultraviolet-visible spectrometry (UV-Vis). Monometallic palladium particles have

  5. 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

  6. A charged residue at the subunit interface of PCNA promotes trimer formation by destabilizing alternate subunit interactions

    International Nuclear Information System (INIS)

    Freudenthal, Bret D.; Gakhar, Lokesh; Ramaswamy, S.; Washington, M. Todd

    2009-01-01

    Eukaryotic proliferating cell nuclear antigen (PCNA), an essential accessory factor in DNA replication and repair, is a ring-shaped homotrimer. A novel nontrimeric structure of E113G-mutant PCNA protein is reported, which shows that this protein forms alternate subunit interactions. It is concluded that the charged side chain of Glu113 promotes normal trimer formation by destabilizing these alternate subunit interactions. Eukaryotic proliferating cell nuclear antigen (PCNA) is an essential replication accessory factor that interacts with a variety of proteins involved in DNA replication and repair. Each monomer of PCNA has an N-terminal domain A and a C-terminal domain B. In the structure of the wild-type PCNA protein, domain A of one monomer interacts with domain B of a neighboring monomer to form a ring-shaped trimer. Glu113 is a conserved residue at the subunit interface in domain A. Two distinct X-ray crystal structures have been determined of a mutant form of PCNA with a substitution at this position (E113G) that has previously been studied because of its effect on translesion synthesis. The first structure was the expected ring-shaped trimer. The second structure was an unanticipated nontrimeric form of the protein. In this nontrimeric form, domain A of one PCNA monomer interacts with domain A of a neighboring monomer, while domain B of this monomer interacts with domain B of a different neighboring monomer. The B–B interface is stabilized by an antiparallel β-sheet and appears to be structurally similar to the A–B interface observed in the trimeric form of PCNA. The A–A interface, in contrast, is primarily stabilized by hydrophobic interactions. Because the E113G substitution is located on this hydrophobic surface, the A–A interface should be less favorable in the case of the wild-type protein. This suggests that the side chain of Glu113 promotes trimer formation by destabilizing these possible alternate subunit interactions

  7. Determinants of RNA polymerase alpha subunit for interaction with beta, beta', and sigma subunits: hydroxyl-radical protein footprinting.

    OpenAIRE

    Heyduk, T; Heyduk, E; Severinov, K; Tang, H; Ebright, R H

    1996-01-01

    Escherichia coli RNA polymerase (RNAP) alpha subunit serves as the initiator for RNAP assembly, which proceeds according to the pathway 2 alpha-->alpha 2-->alpha 2 beta-->alpha 2 beta beta'-->alpha 2 beta beta' sigma. In this work, we have used hydroxyl-radical protein footprinting to define determinants of alpha for interaction with beta, beta', and sigma. Our results indicate that amino acids 30-75 of alpha are protected from hydroxyl-radical-mediated proteolysis upon interaction with beta ...

  8. Heterotrimeric G protein subunits are located on rat liver endosomes

    Directory of Open Access Journals (Sweden)

    Van Dyke Rebecca W

    2004-01-01

    Full Text Available Abstract Background Rat liver endosomes contain activated insulin receptors and downstream signal transduction molecules. We undertook these studies to determine whether endosomes also contain heterotrimeric G proteins that may be involved in signal transduction from G protein-coupled receptors. Results By Western blotting Gsα, Giα1,2, Giα3 and Gβ were enriched in both canalicular (CM and basolateral (BLM membranes but also readily detectable on three types of purified rat liver endosomes in the order recycling receptor compartment (RRC > compartment for uncoupling of receptor and ligand (CURL > multivesicular bodies (MVB >> purified secondary lysosomes. Western blotting with antibodies to Na, K-ATPase and to other proteins associated with plasma membranes and intracellular organelles indicated this was not due to contamination of endosome preparations by CM or BLM. Adenylate cyclase (AC was also identified on purified CM, BLM, RRC, CURL and MVB. Percoll gradient fractionation of liver postnuclear supernatants demonstrated co-occurrence of endosomes and heterotrimeric G protein subunits in fractions with little plasma membrane markers. By confocal microscopy, punctate staining for Gsα, Giα3 and Gβ corresponded to punctate areas of endocytosed Texas red-dextran in hepatocytes from control and cholera toxin-treated livers. Conclusion We conclude that heterotrimeric G protein subunits as well as AC likely traffic into hepatocytes on endosome membranes, possibly generating downstream signals spatially separate from signalling generated at the plasma membrane, analogous to the role(s of internalized insulin receptors.

  9. 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. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  10. 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. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  11. Binding of ATP by pertussis toxin and isolated toxin subunits

    International Nuclear Information System (INIS)

    Hausman, S.Z.; Manclark, C.R.; Burns, D.L.

    1990-01-01

    The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of [ 3 H]ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of [ 3 H]ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of [ 3 H]ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site

  12. Binding of ATP by pertussis toxin and isolated toxin subunits

    Energy Technology Data Exchange (ETDEWEB)

    Hausman, S.Z.; Manclark, C.R.; Burns, D.L. (Center for Biologics Evaluation and Research, Bethesda, MD (USA))

    1990-07-03

    The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of ({sup 3}H)ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of ({sup 3}H)ATP to pertussis toxin in a competitive manner; however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of ({sup 3}H)ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site.

  13. A new non-catalytic role for ubiquitin ligase RNF8 in unfolding higher-order chromatin structure

    DEFF Research Database (Denmark)

    Luijsterburg, Martijn S; Acs, Klara; Ackermann, Leena

    2012-01-01

    The ubiquitin ligases RNF8 and RNF168 orchestrate DNA damage signalling through the ubiquitylation of histone H2A and the recruitment of downstream repair factors. Here, we demonstrate that RNF8, but not RNF168 or the canonical H2A ubiquitin ligase RNF2, mediates extensive chromatin decondensation....... Our data show that CHD4, the catalytic subunit of the NuRD complex, interacts with RNF8 and is essential for RNF8-mediated chromatin unfolding. The chromatin remodelling activity of CHD4 promotes efficient ubiquitin conjugation and assembly of RNF168 and BRCA1 at DNA double-strand breaks....... Interestingly, RNF8-mediated recruitment of CHD4 and subsequent chromatin remodelling were independent of the ubiquitin-ligase activity of RNF8, but involved a non-canonical interaction with the forkhead-associated (FHA) domain. Our study reveals a new mechanism of chromatin remodelling-assisted ubiquitylation...

  14. 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

    study on PDE6C mutations including the mutation spectrum, its prevalence in a large cohort of ACHM/cone dysfunction patients, the clinical phenotype and the functional characterization of mutant PDE6C proteins. Twelve affected patients from seven independent families segregating PDE6C mutations were......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...... identified in our total patient cohort of 492 independent families. Eleven different PDE6C mutations were found including two nonsense mutations, three mutations affecting transcript splicing as shown by minigene assays, one 1 bp-insertion and five missense mutations. We also performed a detailed functional...

  15. Ferredoxin-thioredoxin reductase: a catalytically active dithiol group links photoreduced ferredoxin to thioredoxin functional in photosynthetic enzyme regulation

    International Nuclear Information System (INIS)

    Droux, M.; Miginiac-Maslow, M.; Jacquot, J.P.; Gadal, P.; Crawford, N.A.; Kosower, N.S.; Buchanan, B.B.

    1987-01-01

    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 [ 14 C]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

  16. 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...... the autophosphorylation site. It is suggested that the acidic domain of the beta subunit, encompassing residues 55-71, plays a role in the interactions between the beta and alpha subunits....

  17. Amine binding and oxidation at the catalytic site for photosynthetic water oxidation

    Science.gov (United States)

    Ouellette, Anthony J. A.; Anderson, Lorraine B.; Barry, Bridgette A.

    1998-01-01

    Photosynthetic water oxidation occurs at the Mn-containing catalytic site of photosystem II (PSII). By the use of 14C-labeled amines and SDS-denaturing PAGE, covalent adducts derived from primary amines and the PSII subunits, CP47, D2/D1, and the Mn-stabilizing protein, can be observed. When PSII contains the 18- and 24-kDa extrinsic proteins, which restrict access to the active site, no 14C labeling is obtained. NaCl, but not Na2SO4, competes with 14C labeling in Mn-containing PSII preparations, and the concentration dependence of this competition parallels the activation of oxygen evolution. Formation of 14C-labeled adducts is observed in the presence or in the absence of a functional manganese cluster. However, no significant Cl− effect on 14C labeling is observed in the absence of the Mn cluster. Isolation and quantitation of the 14C-labeled aldehyde product, produced from [14C]benzylamine, gives yields of 1.8 ± 0.3 mol/mol PSII and 2.9 ± 0.2 mol/mol in Mn-containing and Mn-depleted PSII, respectively. The corresponding specific activities are 0.40 ± 0.07 μmol(μmol PSII-hr)−1 and 0.64 ± 0.04 μmol(μmol PSII-hr)−1. Cl− suppresses the production of [14C]benzaldehyde in Mn-containing PSII, but does not suppress the production in Mn-depleted preparations. Control experiments show that these oxidation reactions do not involve the redox-active tyrosines, D and Z. Our results suggest the presence of one or more activated carbonyl groups in protein subunits that form the active site of PSII. PMID:9482863

  18. Efficient expression of functional (α6β22β3 AChRs in Xenopus oocytes from free subunits using slightly modified α6 subunits.

    Directory of Open Access Journals (Sweden)

    Carson Kai-Kwong Ley

    Full Text Available Human (α6β2(α4β2β3 nicotinic acetylcholine receptors (AChRs are essential for addiction to nicotine and a target for drug development for smoking cessation. Expressing this complex AChR is difficult, but has been achieved using subunit concatamers. In order to determine what limits expression of α6* AChRs and to efficiently express α6* AChRs using free subunits, we investigated expression of the simpler (α6β22β3 AChR. The concatameric form of this AChR assembles well, but is transported to the cell surface inefficiently. Various chimeras of α6 with the closely related α3 subunit increased expression efficiency with free subunits and produced pharmacologically equivalent functional AChRs. A chimera in which the large cytoplasmic domain of α6 was replaced with that of α3 increased assembly with β2 subunits and transport of AChRs to the oocyte surface. Another chimera replacing the unique methionine 211 of α6 with leucine found at this position in transmembrane domain 1 of α3 and other α subunits increased assembly of mature subunits containing β3 subunits within oocytes. Combining both α3 sequences in an α6 chimera increased expression of functional (α6β22β3 AChRs to 12-fold more than with concatamers. This is pragmatically useful, and provides insights on features of α6 subunit structure that limit its expression in transfected cells.

  19. Antibodies to the α-subunit of insulin receptor from eggs of immunized hens

    International Nuclear Information System (INIS)

    Song, C.; Yu, J.; Bai, D.H.; Hester, P.Y.; Kim, K.

    1985-01-01

    Simple methods for the generation, purification, and assay of antibodies to the α-subunit of insulin receptor from eggs of immunized hen have been described. Chicken antibodies against the α-subunit inhibit insulin binding to the receptor and stimulate glucose oxidation as well as autophosphorylation of the β-subunit. Thus the properties of chicken antibodies are very similar to those of antibodies found in human autoimmune diseases and different from rabbit antibodies obtained against the same antigen

  20. Cloning and sequencing of the casein kinase 2 alpha subunit from Zea mays

    DEFF Research Database (Denmark)

    Dobrowolska, G; Boldyreff, B; Issinger, O G

    1991-01-01

    The nucleotide sequence of the cDNA coding for the alpha subunit of casein kinase 2 of Zea mays has been determined. The cDNA clone contains an open reading frame of 996 nucleotides encoding a polypeptide comprising 332 amino acids. The primary amino acid sequence exhibits 75% identity to the alpha...... subunit and 71% identity to the alpha' subunit of human casein kinase 2....

  1. Crystal structure of the regulatory subunit of archaeal initiation factor 2B (aIF2B) from hyperthermophilic archaeon Pyrococcus horikoshii OT3: a proposed structure of the regulatory subcomplex of eukaryotic IF2B

    International Nuclear Information System (INIS)

    Kakuta, Yoshimitsu; Tahara, Maino; Maetani, Shigehiro; Yao, Min; Tanaka, Isao; Kimura, Makoto

    2004-01-01

    Eukaryotic translation initiation factor 2B (eIF2B) is the guanine-nucleotide exchange factor for eukaryotic initiation factor 2 (eIF2). eIF2B is a heteropentameric protein composed of α-ε subunits. The α, β, and δ subunits form a regulatory subcomplex, while the γ and ε form a catalytic subcomplex. Archaea possess homologues of α, β, and δ subunits of eIF2B. Here, we report the three-dimensional structure of an archaeal regulatory subunit (aIF2Bα) from the hyperthermophilic archaeon Pyrococcus horikoshii OT3 determined by X-ray crystallography at 2.2 A resolution. aIF2Bα consists of two subdomains, an N-domain (residues 1-95) and a C-domain (residues 96-276), connected by a long α-helix (α5: 78-106). The N-domain contains a five helix bundle structure, while the C-domain folds into the α/β structure, thus showing similarity to D-ribose-5-phosphate isomerase structure. The presence of two molecules in the crystallographic asymmetric unit and the gel filtration analysis suggest a dimeric structure of aIF2Bα in solution, interacting with each other by C-domains. Furthermore, the crystallographic 3-fold symmetry generates a homohexameric structure of aIF2Bα; the interaction is primarily mediated by the long α-helix at the N-domains. This structure suggests an architecture of the three subunits, α, β, and δ, in the regulatory subcomplex within eIF2B

  2. Hydrogen Production From catalytic reforming of greenhouse gases ...

    African Journals Online (AJOL)

    ADOWIE PERE

    a fixed bed stainless steel reactor. The 20wt%. ... catalytic activity for hydrogen production with the highest yield and selectivity of 32.5% and 17.6% respectively. © JASEM ... CO2 reforming of methane is however not fully developed ..... Design and preparation of .... catalytic nickel membrane for gas to liquid (GTL) process.

  3. Catalytic synthesis of ammonia using vibrationally excited nitrogen molecules

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, Gert D.

    1992-01-01

    The dissociation of nitrogen is the rate-limiting step in the catalytic synthesis of ammonia. Theoretical calculations have shown that the dissociative sticking probability of molecular nitrogen on catalytic active metal surfaces is enhanced by orders of magnitude when the molecules...

  4. synthesis, characterization, electrical and catalytic studies of some

    African Journals Online (AJOL)

    B. S. Chandravanshi

    catalytic activity of the VO(IV) and Mn(III) complexes have been tested in the epoxidation reaction of styrene ... Vanadyl sulfate pentahydrate, chromium chloride hexahydrate, anhydrous ferric ..... The catalytic oxidation of styrene gives the products styrene oxide, benzaldehyde, benzoic acid, ... bond via a radical mechanism.

  5. 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

    2006-05-05

    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.

  6. Identification of karyopherins involved in the nuclear import of RNA exosome subunit Rrp6 in Saccharomyces cerevisiae.

    Science.gov (United States)

    Gonzales-Zubiate, Fernando A; Okuda, Ellen K; Da Cunha, Julia P C; Oliveira, Carla Columbano

    2017-07-21

    The exosome is a conserved multiprotein complex essential for RNA processing and degradation. The nuclear exosome is a key factor for pre-rRNA processing through the activity of its catalytic subunits, Rrp6 and Rrp44. In Saccharomyces cerevisiae , Rrp6 is exclusively nuclear and has been shown to interact with exosome cofactors. With the aim of analyzing proteins associated with the nuclear exosome, in this work, we purified the complex with Rrp6-TAP, identified the co-purified proteins by mass spectrometry, and found karyopherins to be one of the major groups of proteins enriched in the samples. By investigating the biological importance of these protein interactions, we identified Srp1, Kap95, and Sxm1 as the most important karyopherins for Rrp6 nuclear import and the nuclear localization signals recognized by them. Based on the results shown here, we propose a model of multiple pathways for the transport of Rrp6 to the nucleus. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. On the Trails of the Proteasome Fold: Structural and Functional Analysis of the Ancestral β-Subunit Protein Anbu.

    Science.gov (United States)

    Vielberg, Marie-Theres; Bauer, Verena C; Groll, Michael

    2018-03-02

    The 20S proteasome is a key player in eukaryotic and archaeal protein degradation, but its progenitor in eubacteria is unknown. Recently, the ancestral β-subunit protein (Anbu) was predicted to be the evolutionary precursor of the proteasome. We crystallized Anbu from Hyphomicrobium sp. strain MC1 in four different space groups and solved the structures by SAD-phasing and Patterson search calculation techniques. Our data reveal that Anbu adopts the classical fold of Ntn-hydrolases, but its oligomeric state differs from that of barrel-shaped proteases. In contrast to their typical architecture, the Anbu protomer is a tightly interacting dimer that can assemble into a helical superstructure. Although Anbu features a catalytic triad of Thr1O γ , Asp17O δ1 and Lys32N ε , it is unable to hydrolyze standard protease substrates. The lack of activity might be caused by the incapacity of Thr1NH 2 to function as a Brønsted acid during substrate cleavage due to its missing activation via hydrogen bonding. Altogether, we demonstrate that the topology of the proteasomal fold is conserved in Anbu, but whether it acts as a protease still needs to be clarified. Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Distinct forms of the β subunit of GTP-binding regulatory proteins identified by molecular cloning

    International Nuclear Information System (INIS)

    Fong, H.K.W.; Amatruda, T.T. III; Birren, B.W.; Simon, M.I.

    1987-01-01

    Two distinct β subunits of guanine nucleotide-binding regulatory proteins have been identified by cDNA cloning and are referred to as β 1 and β 1 subunits. The bovine transducin β subunit (β 1 ) has been cloned previously. The author now isolated and analyzed cDNA clones that encode the β 2 subunit from bovine adrenal, bovine brain, and a human myeloid leukemia cell line, HL-60. The 340-residue M/sub r/ 37,329 Β 2 protein is 90% identical with β 1 in predicted amino acid sequence, and it is also organized as a series of repetitive homologous segments. The major mRNA that encodes the bovine β 2 subunit is 1.7 kilobases in length. It is expressed at lower levels than β 1 subunit mRNA in all tissues examined. The β 1 and β 2 messages are expressed in cloned human cell lines. Hybridization of cDNA probes to bovine DNA showed that β 1 and β 2 are encoded by separate genes. The amino acid sequences for the bovine and human β 2 subunit are identical, as are the amino acid sequences for the bovine and human β 1 subunit. This evolutionary conservation suggests that the two β subunits have different roles in the signal transduction process

  9. Translation activity of chimeric ribosomes composed of Escherichia coli and Bacillus subtilis or Geobacillus stearothermophilus subunits

    Directory of Open Access Journals (Sweden)

    Sayaka Tsuji

    2017-07-01

    Full Text Available Ribosome composition, consisting of rRNA and ribosomal proteins, is highly conserved among a broad range of organisms. However, biochemical studies focusing on ribosomal subunit exchangeability between organisms remain limited. In this study, we show that chimeric ribosomes, composed of Escherichia coli and Bacillus subtilis or E. coli and Geobacillus stearothermophilus subunits, are active for β-galactosidase translation in a highly purified E. coli translation system. Activities of the chimeric ribosomes showed only a modest decrease when using E. coli 30 S subunits, indicating functional conservation of the 50 S subunit between these bacterial species.

  10. Specific radioimmunoassay of HCG and its α and β subunits: methods and results

    International Nuclear Information System (INIS)

    Reuter, A.M.; Schoonbrood, J.; Franchimont, P.

    1976-01-01

    To create antisera that are specific for the radioimmunoassay of HCG and its subunits, the antisera are neutralized by incubation with LH or HCG. For each RIA system the inhibition curves of HCG and its subunits LH, FSH, TSH and STH are obtained. The 125 I labelled hormones HCG, α and β subunits and LH were chromatographed over a Sephadex G 100 column. Serum of menopausal and pregnant women were chromatographed in the same way and the fractions subjected to RIA. HCG and its subunits were determined by RIA in the sera of patients with different kinds of cancer

  11. Induction of 26S proteasome subunit PSMB5 by the bifunctional inducer 3-methylcholanthrene through the Nrf2-ARE, but not the AhR/Arnt-XRE, pathway

    International Nuclear Information System (INIS)

    Kwak, Mi-Kyoung; Kensler, Thomas W.

    2006-01-01

    The 26S proteasome is responsible for degradation of abnormal intracellular proteins, including oxidatively damaged proteins and may play a role as a component of a cellular antioxidative system. However, little is known about regulation of proteasome expression. In the present study, regulation of proteasome expression by the bifunctional enzyme inducer and a specific signaling pathway for this regulation were investigated in murine neuroblastoma cells. Expression of catalytic core subunits including PSMB5 and peptidase activities of the proteasome were elevated following incubation with 3-methylcholanthrene (3-MC). Studies using reporter genes containing the murine Psmb5 promoter showed that transcriptional activity of this gene was enhanced by 3-MC. Overexpression of AhR/Arnt did not affect activation of the Pmsb5 promoter by 3-MC and deletion of the xenobiotic response elements (XREs) from this promoter exerted modest effects on inducibility in response to 3-MC. However, mutation of the proximal AREs of the Psmb5 promoter largely abrogated its inducibility by 3-MC. In addition, this promoter showed a blunted response toward 3-MC in the absence of nrf2; 3-MC incubation increased nuclear levels of Nrf2 only in wild-type cells. Collectively, these results indicate that expression of proteasome subunit PSMB5 is modulated by bifunctional enzyme inducers in a manner independent of the AhR/Arnt-XRE pathway but dependent upon the Nrf2-ARE pathway

  12. 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)

    Sung, Uhna; Jennings, Jennifer L.; Link, Andrew J.; Blakely, Randy D.

    2005-01-01

    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 NH 2 -terminus for interactions. The transporter complexes described likely support mechanisms regulating transporter activity, localization, and trafficking

  13. 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.

  14. Radiant non-catalytic recuperative reformer

    Energy Technology Data Exchange (ETDEWEB)

    Khinkis, Mark J.; Kozlov, Aleksandr P.

    2017-10-31

    A radiant, non-catalytic recuperative reformer has a flue gas flow path for conducting hot exhaust 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 positioned adjacent to the flue gas flow path to permit heat transfer from the hot exhaust 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, a portion of the reforming mixture flow path is positioned outside of flue gas flow path for a relatively large residence time.

  15. Chemical and catalytic effects of ion implantation

    International Nuclear Information System (INIS)

    Wolf, G.K.

    1982-01-01

    Energetic particles are used for inducing chemical reactions as well as for modifying the properties of materials with regard to their bulk and surface chemical behavior. The effects are partly caused by radiation damage or phase intermixing, partly by the chemical properties of the individual bombarding particles. In this contribution a survey of relevant applications of these techniques is presented: (1) Chemical reactions of implanted and recoil atoms and their use for syntheses, doping and labeling of compounds. (2) The formation of thin films by decomposing chemical compounds with ion beams. 3) Catalytic effects on substrates treated by sputtering or ion implantation. Recent results with nonmetallic substrates are reviewed. Mainly hydrogenation reactions at a solid/gas interface or redox reactions at an electrified solid/liquid interface are mentioned. The present status and future prospects of these kinds of investigations will be discussed. (author)

  16. Contact structure for use in catalytic distillation

    Science.gov (United States)

    Jones, E.M. Jr.

    1984-03-27

    A method is described 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 catalyst 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. 7 figs.

  17. Direct catalytic asymmetric aldol-Tishchenko reaction.

    Science.gov (United States)

    Gnanadesikan, Vijay; Horiuchi, Yoshihiro; Ohshima, Takashi; Shibasaki, Masakatsu

    2004-06-30

    A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.

  18. 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

  19. Smoke emissions from a catalytic wood stove

    International Nuclear Information System (INIS)

    Cowburn, D.A.; Stephens, N.P.J.

    1994-01-01

    The work reported here was concerned with testing a catalytic wood burning stove (roomheater) following the most applicable UK procedures. The identical stove has also been tested in several other nations to their individual procedures. The results will be submitted to the International Energy Agency (IEA) such that appropriate comparisons can be made. The results comprised: burning rate; an indicative appliance efficiency; heat output; carbon dioxide emissions; carbon monoxide emissions; and smoke emissions. These results were determined with the appliance at three nominal burning rates (high, medium and low). Comparing the results with those obtained in other countries indicates good agreement except when the appliance was operated at low burning rates, under which conditions the UK results indicate significantly worse smoke emissions than those measured by other researchers. (author)

  20. Flowthrough Reductive Catalytic Fractionation of Biomass

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Eric M.; Stone, Michael L.; Katahira, Rui; Reed, Michelle; Beckham, Gregg T.; Román-Leshkov, Yuriy

    2017-11-01

    Reductive catalytic fractionation (RCF) has emerged as a leading biomass fractionation and lignin valorization strategy. Here, flowthrough reactors were used to investigate RCF of poplar. Most RCF studies to date have been conducted in batch, but a flow-based process enables the acquisition of intrinsic kinetic and mechanistic data essential to accelerate the design, optimization, and scale-up of RCF processes. Time-resolved product distributions and yields obtained from experiments with different catalyst loadings were used to identify and deconvolute events during solvolysis and hydrogenolysis. Multi-bed RCF experiments provided unique insights into catalyst deactivation, showing that leaching, sintering, and surface poisoning are causes for decreased catalyst performance. The onset of catalyst deactivation resulted in higher concentrations of unsaturated lignin intermediates and increased occurrence of repolymerization reactions, producing high-molecular-weight species. Overall, this study demonstrates the concept of flowthrough RCF, which will be vital for realistic scale-up of this promising approach.

  1. Propulsion Mechanism of Catalytic Microjet Engines.

    Science.gov (United States)

    Fomin, Vladimir M; Hippler, Markus; Magdanz, Veronika; Soler, Lluís; Sanchez, Samuel; Schmidt, Oliver G

    2014-02-01

    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 μ m/s. This mechanism provides a fundamental explanation for the development of driving forces that are acting on bubbles in tubular microjets.

  2. 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...

  3. Soluble organic nanotubes for catalytic systems

    Science.gov (United States)

    Xiong, Linfeng; Yang, Kunran; Zhang, Hui; Liao, Xiaojuan; Huang, Kun

    2016-03-01

    In this paper, we report a novel method for constructing a soluble organic nanotube supported catalyst system based on single-molecule templating of core-shell bottlebrush copolymers. Various organic or metal catalysts, such as sodium prop-2-yne-1-sulfonate (SPS), 1-(2-(prop-2-yn-1-yloxy)ethyl)-1H-imidazole (PEI) and Pd(OAc)2 were anchored onto the tube walls to functionalize the organic nanotubes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Depending on the ‘confined effect’ and the accessible cavity microenvironments of tubular structures, the organic nanotube catalysts showed high catalytic efficiency and site-isolation features. We believe that the soluble organic nanotubes will be very useful for the development of high performance catalyst systems due to their high stability of support, facile functionalization and attractive textural properties.

  4. Soluble organic nanotubes for catalytic systems.

    Science.gov (United States)

    Xiong, Linfeng; Yang, Kunran; Zhang, Hui; Liao, Xiaojuan; Huang, Kun

    2016-03-18

    In this paper, we report a novel method for constructing a soluble organic nanotube supported catalyst system based on single-molecule templating of core–shell bottlebrush copolymers. Various organic or metal catalysts, such as sodium prop-2-yne-1-sulfonate (SPS), 1-(2-(prop-2-yn-1-yloxy)ethyl)-1H-imidazole (PEI) and Pd(OAc)2 were anchored onto the tube walls to functionalize the organic nanotubes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. Depending on the 'confined effect' and the accessible cavity microenvironments of tubular structures, the organic nanotube catalysts showed high catalytic efficiency and site-isolation features. We believe that the soluble organic nanotubes will be very useful for the development of high performance catalyst systems due to their high stability of support, facile functionalization and attractive textural properties.

  5. Effect of HMM Glutenin Subunits on Wheat Quality Attributes

    Directory of Open Access Journals (Sweden)

    Daniela Horvat

    2009-01-01

    Full Text Available Glutenin is a group of polymeric gluten proteins. Glutenin molecules consist of glutenin subunits linked together with disulphide bonds and having higher (HMM-GS and lower (LMM-GS molecular mass. The main objective of this study is the evaluation of the influence of HMM-GS on flour processing properties. Seven bread wheat genotypes with contrasting quality attributes and different HMM-GS composition were analyzed during three years. The composition and quantity of HMM-GS were determined by SDS-PAGE and RP-HPLC, respectively. The quality diversity among genotypes was estimated by the analysis of wheat grain, and flour and bread quality parameters. The presence of HMM glutenin subunits 1 and 2* at Glu-A1 and the subunits 5+10 at Glu-D1 loci, as well as a higher proportion of total HMM-GS, had a positive effect on wheat quality. Cluster analysis of the three groups of data (genotype and HMM-GS, flour and bread quality, and dough rheology yielded the same hierarchical structure for the first top three levels, and similarity of the corresponding dendrograms was proved by the principal eigenvalues of the corresponding Euclidian distance matrices. The obtained similarity in classification based on essentially different types of measurements reflects strong natural association between genetic data, product quality and physical properties. Principal component analysis (PCA was applied to effectively reduce large data set into lower dimensions of latent variables amenable for the analysis. PCA analysis of the total set of data (15 variables revealed a very strong interrelationship between the variables. The first three PCA components accounted for 96 % of the total variance, which was significant to the level of 0.05 and was considered as the level of experimental error. These data imply that the quality of wheat cultivars can be contributed to HMM-GS data and should be taken into account in breeding programs assisted by computer models with the aim to

  6. Catalytic flash pyrolysis of oil-impregnated-wood and jatropha cake using sodium based catalysts

    KAUST Repository

    Imran, Ali; Bramer, Eddy A.; Seshan, Kulathuiyer; Brem, Gerrit

    2015-01-01

    Catalytic pyrolysis of wood with impregnated vegetable oil was investigated and compared with catalytic pyrolysis of jatropha cake making use of sodium based catalysts to produce a high quality bio-oil. The catalytic pyrolysis was carried out in two

  7. Crystal structure of heterodimeric hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 reveals that the small subunit is directly involved in the product chain length regulation.

    Science.gov (United States)

    Sasaki, Daisuke; Fujihashi, Masahiro; Okuyama, Naomi; Kobayashi, Yukiko; Noike, Motoyoshi; Koyama, Tanetoshi; Miki, Kunio

    2011-02-04

    Hexaprenyl diphosphate synthase from Micrococcus luteus B-P 26 (Ml-HexPPs) is a heterooligomeric type trans-prenyltransferase catalyzing consecutive head-to-tail condensations of three molecules of isopentenyl diphosphates (C(5)) on a farnesyl diphosphate (FPP; C(15)) to form an (all-E) hexaprenyl diphosphate (HexPP; C(30)). Ml-HexPPs is known to function as a heterodimer of two different subunits, small and large subunits called HexA and HexB, respectively. Compared with homooligomeric trans-prenyltransferases, the molecular mechanism of heterooligomeric trans-prenyltransferases is not yet clearly understood, particularly with respect to the role of the small subunits lacking the catalytic motifs conserved in most known trans-prenyltransferases. We have determined the crystal structure of Ml-HexPPs both in the substrate-free form and in complex with 7,11-dimethyl-2,6,10-dodecatrien-1-yl diphosphate ammonium salt (3-DesMe-FPP), an analog of FPP. The structure of HexB is composed of mostly antiparallel α-helices joined by connecting loops. Two aspartate-rich motifs (designated the first and second aspartate-rich motifs) and the other characteristic motifs in HexB are located around the diphosphate part of 3-DesMe-FPP. Despite the very low amino acid sequence identity and the distinct polypeptide chain lengths between HexA and HexB, the structure of HexA is quite similar to that of HexB. The aliphatic tail of 3-DesMe-FPP is accommodated in a large hydrophobic cleft starting from HexB and penetrating to the inside of HexA. These structural features suggest that HexB catalyzes the condensation reactions and that HexA is directly involved in the product chain length control in cooperation with HexB.

  8. 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.

  9. 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.

    Directory of Open Access Journals (Sweden)

    Yasser A Mahmmoud

    Full Text Available 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.

  10. 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.)

  11. Catalytic combustion in small wood burning appliances

    Energy Technology Data Exchange (ETDEWEB)

    Oravainen, H [VTT Energy, Jyvaeskylae (Finland)

    1997-12-31

    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.)

  12. Determination of hCG-alpha subunit in threatened pregnancy

    International Nuclear Information System (INIS)

    Talas, M.; Pohanka, J.; Fingerova, H.; Janouskova, M.; Krikal, Z.; Prasilova, J.; Zupkova, H.

    1987-01-01

    Radioimmunoassay of the hCG-alpha subunit was made using an antibody anti hCG-alpha serum, highly purified hCG-alpha for 125 I-labelling and the standard hCG-alpha. Sera of healthy pregnant women sampled throughout the whole pregnancies were used to determine x-bar±S.D. of hCG-alpha for 14-day intervals. Included in the study were groups of women with high risk of premature labor, late toxemia of pregnancy, twins and fetal hypotrophy. It was shown that increased hCG-alpha is found in pregnant women in whom signs of late toxemia of pregnancy are combined with high risk of premature labor, or with twin pregnancies, while in those with fetal hypotrophy hCG-alpha is within normal limits. (author). 3 figs., 7 refs

  13. 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.

  14. 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.

  15. The subunit structure of the extracellular hemoglobin of Biomphalaria glabrata

    International Nuclear Information System (INIS)

    Arndt, Marcio H.L.; Naves, Cristiani F.; Xavier, Luciana P.; Santoro, Marcelo M.

    1997-01-01

    Full text. The hemoglobin of Biomphalaria glabrata was purified to homogeneity by a two step purification protocol using a gel filtration column (Superose 6 HR/Pharmacia ) followed by an anion exchange chromatography (MONO-Q Sepharose/Pharmacia). The dissociation products were analysed by a 5 - 15 % Polyacrylamide gel electrophoresis containing Sodium Dodecyl Sulfate (SDS-PAGE) giving a band of 270 K Daltons and a band of 180 K Daltons after reduction with β-mercaptoethanol. The same profile was obtained in a 3.5 % Agarose gel electrophoresis containing SDS (SDS-AGE) showing additional bands of higher molecular weight. These bands were proposed to be monomers, dimers and trimers and, after reduction in a Bidimensional SDS-AGE, the proposed monomers and dimers were decomposed in two and four bands that were interpreted as 1 - 4 chains. The hemoglobin was digested by four different proteases ( Thrombin, Trypsin, Chymotrypsin and Subtilisin ) showing several equivalent fragments with molecular weights multiples of its minimum molecular weight ( 17.7 K Daltons). The circular dichroism spectrum of the protein showed a characteristic high α-helix content. We proposed that this hemoglobin is a pentamer of approx. 360 K Daltons subunits each formed by two 180 K Daltons chains linked in pairs by disulfide bridges and each of these chains comprises ten Heme binding domains. These data were compared to other Planorbidae extracellular hemoglobins. Up to now, the quaternary structure of this hemoglobin (shape and disposition of the subunits) is unknown. It is intended to elucidate its structure by Small Angle X-Ray Scattering in Brazilian National Laboratory of Synchrotron Light (LNLS). (author)

  16. Differential regulation of thyrotropin subunit apoprotein and carbohydrate biosynthesis by thyroid hormone

    International Nuclear Information System (INIS)

    Taylor, T.; Weintraub, B.D.

    1985-01-01

    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 [ 14 C]alanine and [ 3 H] 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, [ 14 C]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. [ 3 H]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

  17. Copolymer semiconductors comprising thiazolothiazole or benzobisthiazole, or benzobisoxazole electron acceptor subunits, and electron donor subunits, and their uses in transistors and solar cells

    Science.gov (United States)

    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.

  18. Roles of the β subunit hinge domain in ATP synthase F1 sector: Hydrophobic network formed by introduced βPhe174 inhibits subunit rotation

    International Nuclear Information System (INIS)

    Nakanishi-Matsui, Mayumi; Kashiwagi, Sachiko; Kojima, Masaki; Nonaka, Takamasa; Futai, Masamitsu

    2010-01-01

    The ATP synthase β subunit hinge domain (βPhe148 ∼ βGly186, P-loop/α-helixB/loop/β-sheet4, Escherichia coli residue numbering) dramatically changes in conformation upon nucleotide binding. We previously reported that F 1 with the βSer174 to Phe mutation in the domain lowered the γ subunit rotation speed, and thus decreased the ATPase activity [M. Nakanishi-Matsui, S. Kashiwagi, T. Ubukata, A. Iwamoto-Kihara, Y. Wada, M. Futai, Rotational catalysis of Escherichia coli ATP synthase F 1 sector. Stochastic fluctuation and a key domain of the β subunit, J. Biol. Chem. 282 (2007) 20698-20704.]. Homology modeling indicates that the amino acid replacement induces a hydrophobic network, in which the βMet159, βIle163, and βAla167 residues of the β subunit are involved together with the mutant βPhe174. The network is expected to stabilize the conformation of β DP (nucleotide-bound form of the β subunit), resulting in increased activation energy for transition to β E (empty β subunit). The modeling further predicts that replacement of βMet159 with Ala or Ile weakens the hydrophobic network. As expected, these two mutations experimentally suppressed the ATPase activities as well as subunit rotation of βS174F. Furthermore, the rotation rate decreased with the increase of the strength in the hydrophobic network. These results indicate that the smooth conformational change of the β subunit hinge domain is pertinent for the rotational catalysis.

  19. Orion EFT-1 Catalytic Tile Experiment Overview and Flight Measurements

    Science.gov (United States)

    Salazar, Giovanni; Amar, Adam; Hyatt, Andrew; Rezin, Marc D.

    2016-01-01

    This paper describes the design and results of a surface catalysis flight experiment flown on the Orion Multipurpose Crew Vehicle during Exploration Flight Test 1 (EFT1). Similar to previous Space Shuttle catalytic tile experiments, the present test consisted of a highly catalytic coating applied to an instrumented TPS tile. However, the present catalytic tile experiment contained significantly more instrumentation in order to better resolve the heating overshoot caused by the change in surface catalytic efficiency at the interface between two distinct materials. In addition to collecting data with unprecedented spatial resolution of the "overshoot" phenomenon, the experiment was also designed to prove if such a catalytic overshoot would be seen in turbulent flow in high enthalpy regimes. A detailed discussion of the results obtained during EFT1 is presented, as well as the challenges associated with data interpretation of this experiment. Results of material testing carried out in support of this flight experiment are also shown. Finally, an inverse heat conduction technique is employed to reconstruct the flight environments at locations upstream and along the catalytic coating. The data and analysis presented in this work will greatly contribute to our understanding of the catalytic "overshoot" phenomenon, and have a significant impact on the design of future spacecraft.

  20. A Review on Catalytic Membranes Production and Applications

    Directory of Open Access Journals (Sweden)

    Heba Abdallah

    2017-05-01

    Full Text Available The development of the chemical industry regarding reducing the production cost and obtaining a high-quality product with low environmental impact became the essential requirements of the world in these days. The catalytic membrane is considered as one of the new alternative solutions of catalysts problems in the industries, where the reaction and separation can be amalgamated in one unit. The catalytic membrane has numerous advantages such as breaking the thermodynamic equilibrium limitation, increasing conversion rate, reducing the recycle and separation costs. But the limitation or most disadvantages of catalytic membranes related to the high capital costs for fabrication or the fact that manufacturing process is still under development. This review article summarizes the most recent advances and research activities related to preparation, characterization, and applications of catalytic membranes. In this article, various types of catalytic membranes are displayed with different applications and explained the positive impacts of using catalytic membranes in various reactions. Copyright © 2017 BCREC Group. All rights reserved. Received: 1st April 2016; Revised: 14th February 2017; Accepted: 22nd February 2017 How to Cite: Abdallah, H. (2017. A Review on Catalytic Membranes Production and Applications. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 136-156 (doi:10.9767/bcrec.12.2.462.136-156 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.462.136-156

  1. Regulated appearance of NMDA receptor subunits and channel functions during in vitro neuronal differentiation

    NARCIS (Netherlands)

    Jelitai, Márta; Schlett, Katalin; Varju, Patrícia; Eisel, Ulrich; Madarász, Emília

    The schedule of NMDA receptor subunit expression and the appearance of functional NMDA-gated ion channels were investigated during the retinoic acid (RA) induced neuronal differentiation of NE-4C, a p53-deficient mouse neuroectodermal progenitor cell line. NR2A. NR2B, and NR2D subunit transcripts

  2. Differential expression of BK channel isoforms and beta-subunits in rat neuro-vascular tissues

    DEFF Research Database (Denmark)

    Poulsen, Asser Nyander; Wulf, Helle; Hay-Schmidt, Anders

    2009-01-01

    We investigated the expression of splice variants and beta-subunits of the BK channel (big conductance Ca(2+)-activated K(+) channel, Slo1, MaxiK, K(Ca)1.1) in rat cerebral blood vessels, meninges, trigeminal ganglion among other tissues. An alpha-subunit splice variant X1(+24) was found expresse...

  3. Differential antibiotic sensitivity determined by the large ribosomal subunit in thermophilic archaea.

    OpenAIRE

    Ruggero, D; Londei, P

    1996-01-01

    Hybrid ribosomes obtained by mixing the ribosomal subunits of the extremely thermophilic archaea Sulfolobus solfataricus and Desulfurococcus mobilis were tested for their sensitivity to selected antibiotics. It is shown that structural differences in the large ribosomal subunits determine qualitatively and quantitatively the patterns of response to alpha-sarcin and paromomycin in these species.

  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...

  5. 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.

  6. 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 deposited...

  7. Purification of the alpha and beta subunits of phosphorylase kinase for structural studies

    International Nuclear Information System (INIS)

    Sotiroudis, T.G.; Heilmeyer, L.M.G. Jr.; Crabb, J.W.

    1987-01-01

    Structural analysis of the alpha (Mr, 132,000) and beta (Mr, 113,000) subunits of phosphorylase kinase may provide clues to their yet unknown functions however purification remains problematic. Preparative RP-HPLC procedures yield inconveniently large, dilute solutions and concentration steps are required prior to subunit modification and fragmentation. Concentration of the β subunit usually results in significant losses due to insolubility. Using preparative SDS-polyacrylamide gel electrophoresis, they have purified the α, 7 , and β subunits from rabbit muscle phosphorylase kinase in a soluble and concentrated form suitable for structural studies. Phosphorylase kinase labelled with fluorescein isothiocyanate in the α and α' subunits and fully 14 C-S-carboxymethylated was fractionated on a 5% acrylamide Laemmli slab gel. The subunit bands were visualized by fluorescence and by SDS precipitation then excised and electroeluted in the presence of SDS using an ELUTRAP device. From 4.5 mg of enzyme applied to a 4.5 mm thick gel about 70% of the α subunit and about 90% of the β subunit were typically recovered in less than 1 ml with overnight elution

  8. Hydrocarbon conversion with an attenuated superactive multimetallic catalytic composite

    International Nuclear Information System (INIS)

    Antos, G.J.

    1981-01-01

    Hydrocarbons are converted by contacting them at hydrocarbon conversion conditions with a novel attenuated superactive multimetallic catalytic composite comprising a combination of a catalytically effective amount of a pyrolyzed rhenium carbonyl component with a porous carrier material containing a uniform dispersion of catalytically effective amounts of a platinum group component, which is maintained in the elemental metallic state during the incorporation and pyrolysis of the rhenium carbonyl component, and of an iron component. In a highly preferred embodiment, this novel catalytic composite also contains a catalytically effective amount of a halogen component. The platinum group component, pyrolyzed rhenium carbonyl component, iron component and optional halogen component are preferably present in the multimetallic catalytic composite in amounts, calculated on an elemental basis, corresponding to about 0.01 to about 2 wt. % platinum group metal, about 0.01 to about 5 wt. % rhenium, about 0.005 to about 4 wt. % iron and about 0.1 to about 5 wt. % halogen. A key feature associated with the preparation of the subject catalytic composite is reaction of a rhenium carbonyl complex with a porous carrier material containing a uniform dispersion of an iron component and of a platinum group component maintained in the elemental state, whereby the interaction of the rhenium moiety with the platinum group moiety is maximized due to the platinophilic (i.e., platinum-seeking) propensities of the carbon monoxide ligands associated with the rhenium reagent. A specific example of the type of hydrocarbon conversion process disclosed herein is a process for the catalytic reforming of a low octane gasoline fraction wherein the gasoline fraction and a hydrogen stream are contacted with the attenuated superactive multimetallic catalytic composite at reforming conditions

  9. Educação escolar na prisão na visão dos professores: um hiato entre o proposto e o vivido / Prison education in the point of view of teachers: a gap between the expectation and the achievement

    Directory of Open Access Journals (Sweden)

    Elenice Maria Cammarosano Onofre

    2009-01-01

    Full Text Available Este estudo evidencia por meio das vozes dos professores que, embora a prisão seja apontada como espaço de reeducação e ressocialização do homem privado de liberdade, ao construir uma experiência ancorada no exercício autoritário do poder e da dominação, ela acaba por constituir-se, em uma organização cujas relações se socializam na delinqüência. Entre o discurso oficial e o modo de vida instaurado pelas práticas de ressocialização próprias da prisão, estabelecese um hiato: embora se pretenda a humanização do tratamento, incluindo-se neste a educação escolar, as técnicas adotadas põem à mostra seu lado reverso. Os professores participantes da pesquisa, um estudo de caso, que se desenvolveu em presídio masculino, do interior do estado de São Paulo/Br., mostram ter clareza de que a meta da reabilitação tem permanecido, no nível verbal, e evidenciam através de suas falas, que o elemento fundamental da eficácia de seu papel reside noprocesso de resgate da liberdade, e a escola é uma das instituições que melhor cumpre a tarefa de oferecer possibilidades que libertam e unem, ao mesmo tempo. Embora o quadro que se apresentanão seja alentador, dada à falta de transparência das organizações penitenciárias e o hiato entre o discurso oficial e o modo de vida instaurado no espaço prisional que dificultam possíveis melhorias,alguns passos podem ser dados, visto que muitos dos problemas existentes no interior da escola das unidades prisionais têm semelhanças com os de outros espaços escolares.Abstract This paper highlights, through the teacher’s voices, that although prison is pointed out to be a space of reeducation and ressocialization of men in situation of lack of freedom , it is built upon an experience of authoritarian practice of power and domination that results in being an organization whose relations are socialized in delinquency. Between the official speech and the way of life implemented by

  10. Surface composition of carburized tungsten trioxide and its catalytic activity

    International Nuclear Information System (INIS)

    Nakazawa, M.; Okamoto, H.

    1985-01-01

    The surface composition and electronic structure of carburized tungsten trioxide are investigated using x-ray photoelectron spectroscopy (XPS). The relationship between the surface composition and the catalytic activity for methanol electro-oxidation is clarified. The tungsten carbide concentration in the surface layer increases with the carburization time. The formation of tungsten carbide enhances the catalytic activity. On the other hand, the presence of free carbon or tungsten trioxide in the surface layer reduces the activity remarkably. It is also shown that, the higher the electronic density of states near the Fermi level, the higher the catalytic activity

  11. Enhanced propylene production in FCC by novel catalytic materials

    Energy Technology Data Exchange (ETDEWEB)

    Kelkar, C.P.; Harris, D.; Xu, M.; Fu, J. [BASF Catalyst LLC, Iselin, NJ (United States)

    2007-07-01

    Fluid catalytic cracking is expected to increasingly supply the additional incremental requirements for propylene. The most efficient route to increase propylene yield from an FCC unit is through the use of medium pore zeolites such as ZSM-5. ZSM-5 zeolite cracks near linear olefins in the gasoline range to LPG olefins such as propylene and butylenes. This paper will describe catalytic approaches to increase gasoline range olefins and the chemistry of ZSM-5 to crack those olefins. The paper will also describe novel catalytic materials designed to increase propylene. (orig.)

  12. Submitochondrial distributions and stabilities of subunits 4, 5, and 6 of yeast cytochrome oxidase in assembly defective mutants.

    Science.gov (United States)

    Glerum, D M; Tzagoloff, A

    1997-08-04

    The concentration and submitochondrial distribution of the subunit polypeptides of cytochrome oxidase have been studied in wild type yeast and in different mutants impaired in assembly of this respiratory complex. All the subunit polypeptides of the enzyme are associated with mitochondrial membranes of wild type cells, except for a small fraction of subunits 4 and 6 that is recovered in the soluble protein fraction of mitochondria. Cytochrome oxidase mutants consistently display a severe reduction in the steady-state concentration of subunit 1 due to its increased turnover. As a consequence, most of subunit 4, which normally is associated with subunit 1, is found in the soluble fraction. A similar shift from membrane-bound to soluble subunit 6 is seen in mutants blocked in expression of subunit 5a. In contrast, null mutations in COX6 coding for subunit 6 promote loss of subunit 5a. The absence of subunit 5a in the cox6 mutant is the result of proteolytic degradation rather than regulation of its expression by subunit 6. The possible role of the ATP-dependent proteases Rca1p and Afg3p in proteolysis of subunits 1 and 5a has been assessed in strains with combined mutations in COX6, RCA1, and/or AFG3. Immunochemical assays indicate that another protease(s) must be responsible for most of the proteolytic loss of these proteins.

  13. Mining Protein Evolution for Insights into Mechanisms of Voltage-Dependent Sodium Channel Auxiliary Subunits.

    Science.gov (United States)

    Molinarolo, Steven; Granata, Daniele; Carnevale, Vincenzo; Ahern, Christopher A

    2018-02-21

    Voltage-gated sodium channel (VGSC) beta (β) subunits have been called the "overachieving" auxiliary ion channel subunit. Indeed, these subunits regulate the trafficking of the sodium channel complex at the plasma membrane and simultaneously tune the voltage-dependent properties of the pore-forming alpha-subunit. It is now known that VGSC β-subunits are capable of similar modulation of multiple isoforms of related voltage-gated potassium channels, suggesting that their abilities extend into the broader voltage-gated channels. The gene family for these single transmembrane immunoglobulin beta-fold proteins extends well beyond the traditional VGSC β1-β4 subunit designation, with deep roots into the cell adhesion protein family and myelin-related proteins - where inherited mutations result in a myriad of electrical signaling disorders. Yet, very little is known about how VGSC β-subunits support protein trafficking pathways, the basis for their modulation of voltage-dependent gating, and, ultimately, their role in shaping neuronal excitability. An evolutionary approach can be useful in yielding new clues to such functions as it provides an unbiased assessment of protein residues, folds, and functions. An approach is described here which indicates the greater emergence of the modern β-subunits roughly 400 million years ago in the early neurons of Bilateria and bony fish, and the unexpected presence of distant homologues in bacteriophages. Recent structural breakthroughs containing α and β eukaryotic sodium channels containing subunits suggest a novel role for a highly conserved polar contact that occurs within the transmembrane segments. Overall, a mixture of approaches will ultimately advance our understanding of the mechanism for β-subunit interactions with voltage-sensor containing ion channels and membrane proteins.

  14. Topographic antigenic determinants recognized by monoclonal antibodies on human choriogonadotropin beta-subunit

    International Nuclear Information System (INIS)

    Bidart, J.M.; Troalen, F.; Salesse, R.; Bousfield, G.R.; Bohuon, C.J.; Bellet, D.H.

    1987-01-01

    We describe a first attempt to study the antibody-combining sites recognized by monoclonal antibodies raised against the beta-subunit of human choriogonadotropin (hCG). Two groups of antibodies were first defined by their ability to recognize only the free beta-subunit or the free and combined subunit. Antibodies FBT-11 and FBT-11-L bind only to hCG beta-subunit but not to hCG, whereas antibodies FBT-10 and D1E8 bind to both the beta-subunit and the hormone. In both cases, the antigenic determinants were localized to the core of the protein (residues 1-112), indicating the weak immunogenicity of the specific carboxyl-terminal extension of hCG-beta. Nine synthetic peptides spanning different regions of hCG-beta and lutropin-beta were assessed for their capacity to inhibit antibody binding. A synthetic peptide inclusive of the NH2-terminal region (residues 1-7) of the hCG beta-subunit was found to inhibit binding to the radiolabeled subunit of a monoclonal antibody specific for free hCG-beta (FBT-11). Further delineation of the antigenic site recognized by this antibody provided evidence for the involvement of fragment 82-92. Moreover, monoclonal antibody FBT-11 inhibited the recombination of hCG-beta to hCG-alpha, indicating that its antigenic determinant might be located nearby or in the hCG-beta portion interacting with the alpha-subunit. Binding of monoclonal antibody FBT-10, corresponding to the second antigenic determinant, was weakly inhibited by fragment 82-105 and did not impair the recombination of the hCG beta-subunit to the hCG alpha-subunit. Its combining site appeared to be located in a region of the intact native choriogonadotropin present at the surface of the hormone-receptor complex

  15. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    Science.gov (United States)

    Nicholas, Christpher P; Boldingh, Edwin P

    2013-12-17

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and show to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hyrdocarbons into hydrocarbons removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  16. Catalytic Reactor For Oxidizing Mercury Vapor

    Science.gov (United States)

    Helfritch, Dennis J.

    1998-07-28

    A catalytic reactor (10) for oxidizing elemental mercury contained in flue gas is provided. The catalyst reactor (10) comprises within a flue gas conduit a perforated corona discharge plate (30a, b) having a plurality of through openings (33) and a plurality of projecting corona discharge electrodes (31); a perforated electrode plate (40a, b, c) having a plurality of through openings (43) axially aligned with the through openings (33) of the perforated corona discharge plate (30a, b) displaced from and opposing the tips of the corona discharge electrodes (31); and a catalyst member (60a, b, c, d) overlaying that face of the perforated electrode plate (40a, b, c) opposing the tips of the corona discharge electrodes (31). A uniformly distributed corona discharge plasma (1000) is intermittently generated between the plurality of corona discharge electrode tips (31) and the catalyst member (60a, b, c, d) when a stream of flue gas is passed through the conduit. During those periods when corona discharge (1000) is not being generated, the catalyst molecules of the catalyst member (60a, b, c, d) adsorb mercury vapor contained in the passing flue gas. During those periods when corona discharge (1000) is being generated, ions and active radicals contained in the generated corona discharge plasma (1000) desorb the mercury from the catalyst molecules of the catalyst member (60a, b, c, d), oxidizing the mercury in virtually simultaneous manner. The desorption process regenerates and activates the catalyst member molecules.

  17. Catalytic hydrotreatment of refinery waste: Demonstration project

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    The object of this project and report is to produce liquid hydrocarbons by the catalytic hydroprocessing of solid refinery wastes (hard pitches) in order to improve the profitability of deep conversion processes and reduce the excess production of heavy fuels. The project was mostly carried out on the ASVAHL demonstration platform site, at Solaize, and hard pitches were produced primarily by deasphalting of atmospheric or vacuum distillation residues. The project includes two experimental phases and an economic evaluation study phase. In Phase 1, two granular catalysts were used to transform pitch into standard low sulfur fuel oil: a continuously moving bed, with demetallation and conversion catalyst; a fixed bed, with hydrorefining catalyst. In Phase 2 of the project, it was proven that a hydrotreatment process using a finely dispersed catalyst in the feedstock, can, under realistic operating conditions, transform with good yields hard pitch into distillates that can be refined through standard methods. In Phase 3 of the project, it was shown that the economics of such processes are tightly linked to the price differential between white'' and black'' oil products, which is expected to increase in the future. Furthermore, the evolution of environmental constraints will impel the use of such methods, thus avoiding the coproduction of polluting solid residues. 11 figs., 1 tab.

  18. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm

    2000-01-01

    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...... between 0.1 and 0.3 V. There were no Faradaic reactions in the negative polarization region, and there was an anodic current which was less than 16% of the theoretical value for an exclusively Faradaic SO2 oxidation. Therefore the promotion effects at negative polarization are completely non-Faradaic. All...... the promotion effects have been explained as mainly due to charging of the electric double layer at the gold electrode. The effect at -0.2 V also depends on the V2O5 concentration and is more pronounced at higher V2O5 concentrations. This has been ascribed to a destruction of the vanadium polymeric chains...

  19. Additive Manufacturing of Catalytically Active Living Materials.

    Science.gov (United States)

    Saha, Abhijit; Johnston, Trevor G; Shafranek, Ryan T; Goodman, Cassandra J; Zalatan, Jesse G; Storti, Duane W; Ganter, Mark A; Nelson, Alshakim

    2018-04-25

    Living materials, which are composites of living cells residing in a polymeric matrix, are designed to utilize the innate functionalities of the cells to address a broad range of applications such as fermentation and biosensing. Herein, we demonstrate the additive manufacturing of catalytically active living materials (AMCALM) for continuous fermentation. A multi-stimuli-responsive yeast-laden hydrogel ink, based on F127-dimethacrylate, was developed and printed using a direct-write 3D printer. The reversible stimuli-responsive behaviors of the polymer hydrogel inks to temperature and pressure are critical, as they enabled the facile incorporation of yeast cells and subsequent fabrication of 3D lattice constructs. Subsequent photo-cross-linking of the printed polymer hydrogel afforded a robust elastic material. These yeast-laden living materials were metabolically active in the fermentation of glucose into ethanol for 2 weeks in a continuous batch process without significant reduction in efficiency (∼90% yield of ethanol). This cell immobilization platform may potentially be applicable toward other genetically modified yeast strains to produce other high-value chemicals in a continuous biofermentation process.

  20. Plasma-catalytic decomposition of TCE

    Energy Technology Data Exchange (ETDEWEB)

    Vandenbroucke, A.; Morent, R.; De Geyter, N.; Leys, C. [Ghent Univ., Ghent (Belgium). Dept. of Applied Physics; Tuan, N.D.M.; Giraudon, J.M.; Lamonier, J.F. [Univ. des Sciences et Technologies de Lille, Villeneuve (France). Dept. de Catalyse et Chimie du Solide

    2010-07-01

    Volatile organic compounds (VOCs) are gaseous pollutants that pose an environmental hazard due to their high volatility and their possible toxicity. Conventional technologies to reduce the emission of VOCs have their advantages, but they become cost-inefficient when low concentrations have to be treated. In the past 2 decades, non-thermal plasma technology has received growing attention as an alternative and promising remediation method. Non-thermal plasmas are effective because they produce a series of strong oxidizers such as ozone, oxygen radicals and hydroxyl radicals that provide a reactive chemical environment in which VOCs are completely oxidized. This study investigated whether the combination of NTP and catalysis could improve the energy efficiency and the selectivity towards carbon dioxide (CO{sub 2}). Trichloroethylene (TCE) was decomposed by non-thermal plasma generated in a DC-excited atmospheric pressure glow discharge. The production of by-products was qualitatively investigated through FT-IR spectrometry. The results were compared with those from a catalytic reactor. The removal rate of TCE reached a maximum of 78 percent at the highest input energy. The by-products of TCE decomposition were CO{sub 2}, carbon monoxide (CO) hydrochloric acid (HCl) and dichloroacetylchloride. Combining the plasma system with a catalyst located in an oven downstream resulted in a maximum removal of 80 percent, at an energy density of 300 J/L, a catalyst temperature of 373 K and a total air flow rate of 2 slm. 14 refs., 6 figs.

  1. Microchannel Reactor System for Catalytic Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Adeniyi Lawal; Woo Lee; Ron Besser; Donald Kientzler; Luke Achenie

    2010-12-22

    We successfully demonstrated a novel process intensification concept enabled by the development of microchannel reactors, for energy efficient catalytic hydrogenation reactions at moderate temperature, and pressure, and low solvent levels. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for hydrogenation of onitroanisole and a proprietary BMS molecule. In the second phase of the program, as a prelude to full-scale commercialization, we designed and developed a fully-automated skid-mounted multichannel microreactor pilot plant system for multiphase reactions. The system is capable of processing 1 – 10 kg/h of liquid substrate, and an industrially relevant immiscible liquid-liquid was successfully demonstrated on the system. Our microreactor-based pilot plant is one-of-akind. We anticipate that this process intensification concept, if successfully demonstrated, will provide a paradigm-changing basis for replacing existing energy inefficient, cost ineffective, environmentally detrimental slurry semi-batch reactor-based manufacturing practiced in the pharmaceutical and fine chemicals industries.

  2. Catalytic glycerol steam reforming for hydrogen production

    International Nuclear Information System (INIS)

    Dan, Monica; Mihet, Maria; Lazar, Mihaela D.

    2015-01-01

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H 2 . In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al 2 O 3 . The catalyst was prepared by wet impregnation method and characterized through different methods: N 2 adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H 2 , CH 4 , CO, CO 2 . The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H 2 O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%

  3. Catalytic extraction processing of contaminated scrap metal

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M. [Molten Metal Technology, Inc., Waltham, MA (United States)] [and others

    1995-10-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT`s proprietary elemental recycling technology, to DOE`s inventory of low level mixed waste. This includes DOE`s inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D&D) of DOE sites.

  4. Process for catalytic flue gas denoxing

    International Nuclear Information System (INIS)

    Woldhuis, A.; Goudriaan, F.; Groeneveld, M.; Samson, R.

    1991-01-01

    With the increasing concern for the environment, stringency of legislation and industry's awareness of its own environmental responsibility, the demand for the reduction of emission levels of nitrogen oxides is becoming increasingly urgent. This paper reports that Shell has developed a low temperature catalytic deNOx system for deep removal of nitrogen oxides, which includes a low-pressure-drop reactor. This process is able to achieve over 90% removal of nitrogen oxides and therefore can be expected to meet legislation requirements for the coming years. The development of a low-temperature catalyst makes it possible to operate at temperatures as low as 120 degrees C, compared to 300-400 degrees C for the conventional honeycomb and plate-type catalysts. This allows an add-on construction, which is most often a more economical solution than the retrofits in the hot section required with conventional deNOx catalysts. The Lateral Flow Reactor (LFR), which is used for dust-free flue gas applications, and the Parallel Passage Reactor (PPR) for dust-containing flue gas applications, have been developed to work with pressure drops below 10 mbar

  5. Catalytic partial oxidation of pyrolysis oils

    Science.gov (United States)

    Rennard, David Carl

    2009-12-01

    This thesis explores the catalytic partial oxidation (CPO) of pyrolysis oils to syngas and chemicals. First, an exploration of model compounds and their chemistries under CPO conditions is considered. Then CPO experiments of raw pyrolysis oils are detailed. Finally, plans for future development in this field are discussed. In Chapter 2, organic acids such as propionic acid and lactic acid are oxidized to syngas over Pt catalysts. Equilibrium production of syngas can be achieved over Rh-Ce catalysts; alternatively mechanistic evidence is derived using Pt catalysts in a fuel rich mixture. These experiments show that organic acids, present in pyrolysis oils up to 25%, can undergo CPO to syngas or for the production of chemicals. As the fossil fuels industry also provides organic chemicals such as monomers for plastics, the possibility of deriving such species from pyrolysis oils allows for a greater application of the CPO of biomass. However, chemical production is highly dependent on the originating molecular species. As bio oil comprises up to 400 chemicals, it is essential to understand how difficult it would be to develop a pure product stream. Chapter 3 continues the experimentation from Chapter 2, exploring the CPO of another organic functionality: the ester group. These experiments demonstrate that equilibrium syngas production is possible for esters as well as acids in autothermal operation with contact times as low as tau = 10 ms over Rh-based catalysts. Conversion for these experiments and those with organic acids is >98%, demonstrating the high reactivity of oxygenated compounds on noble metal catalysts. Under CPO conditions, esters decompose in a predictable manner: over Pt and with high fuel to oxygen, non-equilibrium products show a similarity to those from related acids. A mechanism is proposed in which ethyl esters thermally decompose to ethylene and an acid, which decarbonylates homogeneously, driven by heat produced at the catalyst surface. Chapter 4

  6. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Griffin, T.P.; Johnston, J.E.; Payea, B.M.

    1995-01-01

    The U.S. Department of Energy issued a Planned Research and Development Announcement (PRDA) in 1993, with the objective of identifying unique technologies which could be applied to the most hazardous waste streams at DOE sites. The combination of radioactive contamination with additional contamination by hazardous constituents such as those identified by the Resource Conservation and Recovery Act (RCRA) pose an especially challenging problem. Traditional remediation technologies are increasingly becoming less acceptable to stakeholders and regulators because of the risks they pose to public health and safety. Desirable recycling technologies were described by the DOE as: (1) easily installed, operated, and maintained; (2) exhibiting superior environmental performance; (3) protective of worker and public health and safety; (4) readily acceptable to a wide spectrum of evaluators; and (5) economically feasible. Molten Metal Technology, Inc. (MMT) was awarded a contract as a result of the PRDA initiative to demonstrate the applicability of Catalytic Extraction Processing (CEP), MMT's proprietary elemental recycling technology, to DOE's inventory of low level mixed waste. This includes DOE's inventory of radioactively- and RCRA-contaminated scrap metal and other waste forms expected to be generated by the decontamination and decommissioning (D ampersand D) of DOE sites

  7. Substrate-Directed Catalytic Selective Chemical Reactions.

    Science.gov (United States)

    Sawano, Takahiro; Yamamoto, Hisashi

    2018-05-04

    The development of highly efficient reactions at only the desired position is one of the most important subjects in organic chemistry. Most of the reactions in current organic chemistry are reagent- or catalyst-controlled reactions, and the regio- and stereoselectivity of the reactions are determined by the inherent nature of the reagent or catalyst. In sharp contrast, substrate-directed reaction determines the selectivity of the reactions by the functional group on the substrate and can strictly distinguish sterically and electronically similar multiple reaction sites in the substrate. In this Perspective, three topics of substrate-directed reaction are mainly reviewed: (1) directing group-assisted epoxidation of alkenes, (2) ring-opening reactions of epoxides by various nucleophiles, and (3) catalytic peptide synthesis. Our newly developed synthetic methods with new ligands including hydroxamic acid derived ligands realized not only highly efficient reactions but also pinpointed reactions at the expected position, demonstrating the substrate-directed reaction as a powerful method to achieve the desired regio- and stereoselective functionalization of molecules from different viewpoints of reagent- or catalyst-controlled reactions.

  8. Catalytic glycerol steam reforming for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Dan, Monica, E-mail: monica.dan@itim-cj.ro; Mihet, Maria, E-mail: maria.mihet@itim-cj.ro; Lazar, Mihaela D., E-mail: diana.lazar@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293 Cluj Napoca (Romania)

    2015-12-23

    Hydrogen production from glycerol by steam reforming combine two major advantages: (i) using glycerol as raw material add value to this by product of bio-diesel production which is obtained in large quantities around the world and have a very limited utilization now, and (ii) by implication of water molecules in the reaction the efficiency of hydrogen generation is increased as each mol of glycerol produces 7 mol of H{sub 2}. In this work we present the results obtained in the process of steam reforming of glycerol on Ni/Al{sub 2}O{sub 3}. The catalyst was prepared by wet impregnation method and characterized through different methods: N{sub 2} adsorption-desorption, XRD, TPR. The catalytic study was performed in a stainless steel tubular reactor at atmospheric pressure by varying the reaction conditions: steam/carbon ratio (1-9), gas flow (35 ml/min -133 ml/min), temperature (450-650°C). The gaseous fraction of the reaction products contain: H{sub 2}, CH{sub 4}, CO, CO{sub 2}. The optimum reaction conditions as resulted from this study are: temperature 550°C, Gly:H{sub 2}O ratio 9:1 and Ar flow 133 ml/min. In these conditions the glycerol conversion to gaseous products was 43% and the hydrogen yield was 30%.

  9. Catalytic extraction processing of contaminated scrap metal

    International Nuclear Information System (INIS)

    Griffin, T.P.; Johnston, J.E.

    1994-01-01

    The contract was conceived to establish the commercial capability of Catalytic Extraction Processing (CEP) to treat contaminated scrap metal in the DOE inventory. In so doing, Molten Metal Technology, Inc. (MMT), pursued the following objectives: demonstration of the recycling of ferrous and non-ferrous metals--to establish that radioactively contaminated scrap metal can be converted to high-grade, ferrous and non-ferrous alloys which can be reused by DOE or reintroduced into commerce; immobilize radionuclides--that CEP will concentrate the radionuclides in a dense vitreous phase, minimize secondary waste generation and stabilize and reduce waste volume; destroy hazardous organics--that CEP will convert hazardous organics to valuable industrial gases, which can be used as feed gases for chemical synthesis or as an energy source; recovery volatile heavy metals--that CEP's off-gas treatment system will capture volatile heavy metals, such as mercury and lead; and establish that CEP is economical for processing contaminated scrap metal in the DOE inventory--that CEP is a more cost-effective and, complete treatment and recycling technology than competing technologies for processing contaminated scrap. The process and its performance are described

  10. Radioisotope applications on fluidized catalytic cracking units

    International Nuclear Information System (INIS)

    Charlton, J.S.

    1997-01-01

    Radioisotopes are used to trace the flow of all the phases of Fluidized Catalytic Cracking process in oil refineries. The gaseous phases, steam, hydrocarbon vapour and air, are generally traced using a noble-gas isotope, 41 Ar, 79 Kr or 85 Kr. An appropriate tracer for the catalyst is produced by irradiating a catalyst sample in a nuclear reactor. The activation products, 140 La and 24 Na provide appropriate radioactive 'labels' for the catalyst, which is reinjected into the FCC. An advantage of this approach is that it facilitates the study of the behaviour of different particle size fractions. Radioisotopes as sealed sources of gamma radiation are used to measure catalyst density variations and density distributions in critical parts of the unit. An important trend in radioisotope applications is the increasing use of the information they produce as inputs to or as validation of, mathematical process models. In line with the increasing sophistication of the models, the technology is undergoing continuous refinement. Developments include the investigation of more efficient, more convenient tracers, the introduction of systems to facilitate more rapid and comprehensive data acquisition and software refinements for enhanced data analysis

  11. Catalytic cleavage activities of 10–23 DNAzyme analogs functionalized with an amino group in its catalytic core

    Directory of Open Access Journals (Sweden)

    Qi Wang

    2012-02-01

    Full Text Available Functionalization of the catalytic loop of 10–23 DNAzyme with an amino group was performed by incorporation of 7-(3-aminopropyl-8-aza-7-deaza-2′-deoxyadenosine in different single positions. Among the nine modified positions in the catalytic loop, A9 is the unique position with positive contribution by such modification. These results indicated that more efficient deoxyribozymes remain to be explored by introduction of exogenous functional groups in an appropriate position in the catalytic loop of 10–23 DNAzyme, such as the combination of 7-functional group substituted 8-aza-7-deaza-2′-deoxyadenosine analogs and A9 position.

  12. Bimetallic Nanoparticles in Alternative Solvents for Catalytic Purposes

    Directory of Open Access Journals (Sweden)

    Trung Dang-Bao

    2017-07-01

    Full Text Available Bimetallic nanoparticles represent attractive catalytic systems thanks to the synergy between both partners at the atomic level, mainly induced by electronic effects which in turn are associated with the corresponding structures (alloy, core-shell, hetero-dimer. This type of engineered material can trigger changes in the kinetics of catalyzed processes by variations on the electrophilicity/nucleophilicity of the metal centers involved and also promote cooperative effects to foster organic transformations, including multi-component and multi-step processes. Solvents become a crucial factor in the conception of catalytic processes, not only due to their environmental impact, but also because they can preserve the bimetallic structure during the catalytic reaction and therefore increase the catalyst life-time. In this frame, the present review focuses on the recent works described in the literature concerning the synthesis of bimetallic nanoparticles in non-conventional solvents, i.e., other than common volatile compounds, for catalytic applications.

  13. Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-01-01

    Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported

  14. Catalytic Oxidation of Cyanogen Chloride over a Monolithic Oxidation Catalyst

    National Research Council Canada - National Science Library

    Campbell, Jeffrey

    1997-01-01

    The catalytic oxidation of cyanogen chloride was evaluated over a monolithic oxidation catalyst at temperatures between 200 and 300 deg C in air employing feed concentrations between 100 and 10,000 ppm...

  15. Highly efficient catalytic systems based on Pd-coated microbeads

    Science.gov (United States)

    Lim, Jin Hyun; Cho, Ahyoung; Lee, Seung Hwan; Park, Bumkyo; Kang, Dong Woo; Koo, Chong Min; Yu, Taekyung; Park, Bum Jun

    2018-01-01

    The efficiency of two prototype catalysis systems using palladium (Pd)-coated microparticles was investigated with regard to the recovery and recyclability of the catalytic particles. One such system was the interface-adsorption method, in which polymer particles coated with Pd nanoparticles strongly and irreversibly attach to the oil-water interface. Due to the irreversible adsorption of the catalytic particles to the interface, particle loss was completely prevented while mixing the aqueous solution and while collecting the products. The other system was based on the magnetic field-associated particle recovery method. The use of polymeric microparticles containing Pd nanoparticles and magnetite nanoparticles accelerated the sedimentation of the particles in the aqueous phase by applying a strong magnetic field, consequently suppressing drainage of the particles from the reactor along the product stream. Upon multiple runs of the catalytic reactions, it was found that conversion does not change significantly, demonstrating the excellent recyclability and performance efficiency in the catalytic processes.

  16. Synthesis of carbon nanotubes by catalytic vapor decomposition ...

    Indian Academy of Sciences (India)

    Carbon nanotubes (CNTs); catalytic vapor decomposition; soap bubble mass flowmeter. ... [4,13,14], makes them an excellent candidate for use as a dielectric in supercapac- itors [15]. ... the change in liquid level in the scrubber. After the ...

  17. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

    and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would

  18. The Catalytic Enantioselective Total Synthesis of (+)‐Liphagal

    DEFF Research Database (Denmark)

    Day, Joshua J.; McFadden, Ryan M.; Virgil, Scott C.

    2011-01-01

    Ring a ding: The first catalytic enantioselective total synthesis of the meroterpenoid natural product (+)-liphagal is disclosed. The approach showcases a variety of technology including enantioselective enolate alkylation, a photochemical alkyne-alkene [2+2] reaction, microwaveassisted metal...

  19. Kinetic Studies of Catalytic Oxidation of Cyclohexene Using ...

    African Journals Online (AJOL)

    acer

    Kinetic Studies of Catalytic Oxidation of Cyclohexene Using Chromium VI Oxide in. Acetic Acid ... respect to the oxidant using pseudo-order approximation method. .... making the concentration of the cyclohexene in ..... on Titanium Silicate.

  20. Processing and structural characterization of porous reforming catalytic films

    International Nuclear Information System (INIS)

    Hou Xianghui; Williams, Jey; Choy, Kwang-Leong

    2006-01-01

    Nickel-based catalysts are often used to reform methanol into hydrogen. The preparation and installation of these catalysts are costly and laborious. As an alternative, directly applying catalytic films onto the separator components can improve the manufacturing efficiency. This paper reports the successful deposition of adherent porous NiO-Al 2 O 3 -based catalytic films with well-controlled stoichiometry, using a single-step Aerosol Assisted Chemical Vapour Deposition (AACVD) method. The microstructure, composition and crystalline phase of the as-deposited catalytic films are characterized using a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FTIR) Spectrometer. The results have demonstrated the capability of AACVD to produce porous NiO-Al 2 O 3 -based catalytic films

  1. Magnetic, catalytic, EPR and electrochemical studies on binuclear ...

    Indian Academy of Sciences (India)

    Magnetic, catalytic, EPR and electrochemical studies on binuclear copper(II) complexes ... to the oxidation of 3,5-di--butylcatechol to the corresponding quinone. ... EPR spectral studies in methanol solvent show welldefined four hyperfine ...

  2. Quantum catalysis : the modelling of catalytic transition states

    NARCIS (Netherlands)

    Hall, M.B.; Margl, P.; Naray-Szabo, G.; Schramm, Vern; Truhlar, D.G.; Santen, van R.A.; Warshel, A.; Whitten, J.L.; Truhlar, D.G.; Morokuma, K.

    1999-01-01

    A review with 101 refs.; we present an introduction to the computational modeling of transition states for catalytic reactions. We consider both homogeneous catalysis and heterogeneous catalysis, including organometallic catalysts, enzymes, zeolites and metal oxides, and metal surfaces. We summarize

  3. 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

  4. Effect of radioactive radiation on catalytic properties of solid materials

    Energy Technology Data Exchange (ETDEWEB)

    Sokol' skii, D V; Kuzembaev, K K; Kel' man, I V [AN Kazakhskoj SSR, Alma-Ata. Inst. Organicheskogo Kataliza i Ehlektrokhimii

    1977-05-01

    General survey is made of the problem of radiation modification of the action of solid catalysts with respect to the various types of heterogeneous catalytic reactions. Consideration is given to the key mechanisms responsible for radiation damage in the interaction of high-energy radiation with a solid body. The effect of ionizing radiation on the adsorption capacity and catalytic activity of solid bodies is discussed.

  5. Catalytic Upgrading of Sugars to Hydrocarbons Technology Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Biddy, M.; Jones, S.

    2013-03-01

    This technology pathway case investigates the catalytic conversion of solubilized carbohydrate streams to hydrocarbon biofuels, utilizing data from recent efforts within the National Advanced Biofuels Consortium (NABC) in collaboration with Virent, Inc. Technical barriers and key research needs that should be pursued for the catalytic conversion of sugars pathway to be competitive with petroleum-derived gasoline-, diesel-, and jet-range hydrocarbon blendstocks have been identified.

  6. Advanced Catalytic Converter in Gasoline Enginer Emission Control: A Review

    OpenAIRE

    Leman A.M.; Jajuli Afiqah; Feriyanto Dafit; Rahman Fakhrurrazi; Zakaria Supaat

    2017-01-01

    Exhaust emission from automobile source has become a major contributor to the air pollution and environmental problem. Catalytic converter is found to be one of the most effective tools to reduce the overwhelming exhaust pollutants in our environment. The development of sustainable catalytic converter still remains a critical issue due to the stringent exhaust emission regulations. Another issue such as price and availability of the precious metal were also forced the automotive industry to i...

  7. Catalytical Properties of Free and Immobilized Aspergillus niger Tannase

    OpenAIRE

    Abril Flores-Maltos; Luis V. Rodríguez-Durán; Jacqueline Renovato; Juan C. Contreras; Raúl Rodríguez; Cristóbal N. Aguilar

    2011-01-01

    A fungal tannase was produced, recovered, and immobilized by entrapment in calcium alginate beads. Catalytical properties of the immobilized enzyme were compared with those of the free one. Tannase was produced intracellularly by the xerophilic fungus Aspergillus niger GH1 in a submerged fermentation system. Enzyme was recovered by cell disruption and the crude extract was partially purified. The catalytical properties of free and immobilized tannase were evaluated using tannic acid and methy...

  8. Application of Zeolitic Additives in the Fluid Catalytic Cracking (FCC

    Directory of Open Access Journals (Sweden)

    A. Nemati Kharat

    2013-06-01

    Full Text Available Current article describes application of zeolites in fluid catalytic cracking (FCC. The use of several zeolitic additives for the production light olefins and reduction of pollutants is described. Application of zeolites as fluid catalytic cracking (FCC catalysts and additives due to the presence of active acid sites in the zeolite framework  increase the formation of desired cracking products (i.e., olefin and branched products  in the FCC unit.

  9. Catalytic Reactor for Inerting of Aircraft Fuel Tanks

    Science.gov (United States)

    1974-06-01

    Aluminum Panels After Triphase Corrosion Test 79 35 Inerting System Flows in Various Flight Modes 82 36 High Flow Reactor Parametric Data 84 37 System...AD/A-000 939 CATALYTIC REACTOR FOR INERTING OF AIRCRAFT FUEL TANKS George H. McDonald, et al AiResearch Manufacturing Company Prepared for: Air Force...190th Street 2b. GROUP Torrance, California .. REPORT TITLE CATALYTIC REACTOR FOR INERTING OF AIRCRAFT FUEL TANKS . OESCRIP TIVE NOTEs (Thpe of refpoft

  10. Aerobic, catalytic oxidation of alcohols in ionic liquids

    Directory of Open Access Journals (Sweden)

    Souza Roberto F. de

    2006-01-01

    Full Text Available An efficient and simple catalytic system based on RuCl3 dissolved in ionic liquids has been developed for the oxidation of alcohols into aldehydes and ketones under mild conditions. A new fluorinated ionic liquid, 1-n-butyl-3-methylimidazolium pentadecafluorooctanoate, was synthesized and demonstrated better performance that the other ionic liquids employed. Moreover this catalytic system utilizes molecular oxygen as an oxidizing agent, producing water as the only by-product.

  11. Subunit association as the stabilizing determinant for archaeal methionine adenosyltransferases.

    Science.gov (United States)

    Garrido, Francisco; Alfonso, Carlos; Taylor, John C; Markham, George D; Pajares, María A

    2009-07-01

    Archaea contain a class of methionine adenosyltransferases (MATs) that exhibit substantially higher stability than their mesophilic counterparts. Their sequences are highly divergent, but preserve the essential active site motifs of the family. We have investigated the origin of this increased stability using chemical denaturation experiments on Methanococcus jannaschii MAT (Mj-MAT) and mutants containing single tryptophans in place of tyrosine residues. The results from fluorescence, circular dichroism, hydrodynamic, and enzyme activity measurements showed that the higher stability of Mj-MAT derives largely from a tighter association of its subunits in the dimer. Local fluorescence changes, interpreted using secondary structure predictions, further identify the least stable structural elements as the C-terminal ends of beta-strands E2 and E6, and the N-terminus of E3. Dimer dissociation however requires a wider perturbation of the molecule. Additional analysis was initially hindered by the lack of crystal structures for archaeal MATs, a limitation that we overcame by construction of a 3D-homology model of Mj-MAT. This model predicts preservation of the chain topology and three-domain organization typical of this family, locates the least stable structural elements at the flat contact surface between monomers, and shows that alterations in all three domains are required for dimer dissociation.

  12. The Regulation of NF-κB Subunits by Phosphorylation

    Directory of Open Access Journals (Sweden)

    Frank Christian

    2016-03-01

    Full Text Available The NF-κB transcription factor is the master regulator of the inflammatory response and is essential for the homeostasis of the immune system. NF-κB regulates the transcription of genes that control inflammation, immune cell development, cell cycle, proliferation, and cell death. The fundamental role that NF-κB plays in key physiological processes makes it an important factor in determining health and disease. The importance of NF-κB in tissue homeostasis and immunity has frustrated therapeutic approaches aimed at inhibiting NF-κB activation. However, significant research efforts have revealed the crucial contribution of NF-κB phosphorylation to controlling NF-κB directed transactivation. Importantly, NF-κB phosphorylation controls transcription in a gene-specific manner, offering new opportunities to selectively target NF-κB for therapeutic benefit. This review will focus on the phosphorylation of the NF-κB subunits and the impact on NF-κB function.

  13. DNA binding properties of the small cascade subunit Csa5.

    Directory of Open Access Journals (Sweden)

    Michael Daume

    Full Text Available CRISPR-Cas systems provide immunity against viral attacks in archaeal and bacterial cells. Type I systems employ a Cas protein complex termed Cascade, which utilizes small CRISPR RNAs to detect and degrade the exogenic DNA. A small sequence motif, the PAM, marks the foreign substrates. Previously, a recombinant type I-A Cascade complex from the archaeon Thermoproteus tenax was shown to target and degrade DNA in vitro, dependent on a native PAM sequence. Here, we present the biochemical analysis of the small subunit, Csa5, of this Cascade complex. T. tenax Csa5 preferentially bound ssDNA and mutants that showed decreased ssDNA-binding and reduced Cascade-mediated DNA cleavage were identified. Csa5 oligomerization prevented DNA binding. Specific recognition of the PAM sequence was not observed. Phylogenetic analyses identified Csa5 as a universal member of type I-A systems and revealed three distinct groups. A potential role of Csa5 in R-loop stabilization is discussed.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    Adenosine to inosine (A-to-I) pre-mRNA editing by the ADAR enzyme family has the potential to increase the variety of the proteome. This editing by adenosine deamination is essential in mammals for a functional brain. To detect novel substrates for A-to-I editing we have used an experimental method...... 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(A) receptor......, is a substrate for editing by both ADAR1 and ADAR2. Editing of the Gabra-3 mRNA recodes an isoleucine to a methionine. The extent of editing is low at birth but increases with age, reaching close to 100% in the adult brain. We therefore propose that editing of the Gabra-3 mRNA is important for normal brain...

  15. Vaccine profile of herpes zoster (HZ/su) subunit vaccine.

    Science.gov (United States)

    Cunningham, Anthony L; Heineman, Thomas

    2017-07-01

    Herpes zoster (HZ) causes an often severe and painful rash in older people and may be complicated by prolonged pain (postherpetic neuralgia; PHN) and by dissemination in immune-compromised patients. HZ results from reactivation of latent varicella-zoster virus (VZV) infection, often associated with age-related or other causes of decreased T cell immunity. A live attenuated vaccine boosts this immunity and provides partial protection against HZ, but this decreases with age and declines over 8 years. Areas covered: A new HZ subunit (HZ/su) vaccine combines a key surface VZV glycoprotein (E) with a T cell-boosting adjuvant system (AS01 B ) and is administered by two intramuscular injections two months apart. Expert commentary: HZ/su showed excellent efficacy of ~90% in immunocompetent adults ≥50 and ≥70 years of age, respectively, in the ZOE-50 and ZOE-70 phase III controlled trials. Efficacy was unaffected by advancing age and persisted for >3 years. Approximately 9.5% of subjects had severe, but transient (1-2 days) injection site pain, swelling or redness. Compliance with both vaccine doses was high (95%). The vaccine will have a major impact on HZ management. Phase I-II trials showed safety and immunogenicity in severely immunocompromised patients. Phase III trial results are expected soon.

  16. Design of a hyperstable 60-subunit protein icosahedron

    Science.gov (United States)

    Hsia, Yang; Bale, Jacob B.; Gonen, Shane; Shi, Dan; Sheffler, William; Fong, Kimberly K.; Nattermann, Una; Xu, Chunfu; Huang, Po-Ssu; Ravichandran, Rashmi; Yi, Sue; Davis, Trisha N.; Gonen, Tamir; King, Neil P.; Baker, David

    2016-07-01

    The icosahedron is the largest of the Platonic solids, and icosahedral protein structures are widely used in biological systems for packaging and transport. There has been considerable interest in repurposing such structures for applications ranging from targeted delivery to multivalent immunogen presentation. The ability to design proteins that self-assemble into precisely specified, highly ordered icosahedral structures would open the door to a new generation of protein containers with properties custom-tailored to specific applications. Here we describe the computational design of a 25-nanometre icosahedral nanocage that self-assembles from trimeric protein building blocks. The designed protein was produced in Escherichia coli, and found by electron microscopy to assemble into a homogenous population of icosahedral particles nearly identical to the design model. The particles are stable in 6.7 molar guanidine hydrochloride at up to 80 degrees Celsius, and undergo extremely abrupt, but reversible, disassembly between 2 molar and 2.25 molar guanidinium thiocyanate. The icosahedron is robust to genetic fusions: one or two copies of green fluorescent protein (GFP) can be fused to each of the 60 subunits to create highly fluorescent ‘standard candles’ for use in light microscopy, and a designed protein pentamer can be placed in the centre of each of the 20 pentameric faces to modulate the size of the entrance/exit channels of the cage. Such robust and customizable nanocages should have considerable utility in targeted drug delivery, vaccine design and synthetic biology.

  17. Fc receptor gamma subunit polymorphisms and systemic lupus erythematosus

    International Nuclear Information System (INIS)

    Al-Ansari, Aliya; Ollier, W.E.; Gonzalez-Gay, Miguel A.; Gul, Ahmet; Inanac, Murat; Ordi, Jose; Teh, Lee-Suan; Hajeer, Ali H.

    2004-01-01

    To investigate the possible association between Fc receptor gamma polymorphisms and systemic lupus erythematosus (SLE). We have investigated the full FcR gamma gene for polymorphisms using polymerase chain reaction (PCR)-single strand confirmational polymorphisms and DNA sequencing .The polymorphisms identified were genotype using PCR-restriction fragment length polymorphism. Systemic lupus erythematosus cases and controls were available from 3 ethnic groups: Turkish, Spanish and Caucasian. The study was conducted in the year 2001 at the Arthritis Research Campaign, Epidemiology Unit, Manchester University Medical School, Manchester, United Kingdom. Five single nucleotide polymorphisms were identified, 2 in the promoter, one in intron 4 and, 2 in the 3'UTR. Four of the 5 single nucleotide polymorphisms (SNPs) were relatively common and investigated in the 3 populations. Allele and genotype frequencies of all 4 investigated SNPs were not statistically different cases and controls. fc receptor gamma gene does not appear to contribute to SLE susceptibility. The identified polymorphisms may be useful in investigating other diseases where receptors containing the FcR gamma subunit contribute to the pathology. (author)

  18. Inhibition of the host proteasome facilitates papaya ringspot virus accumulation and proteosomal catalytic activity is modulated by viral factor HcPro.

    Directory of Open Access Journals (Sweden)

    Nandita Sahana

    Full Text Available The ubiquitin/26S proteasome system plays an essential role not only in maintaining protein turnover, but also in regulating many other plant responses, including plant-pathogen interactions. Previous studies highlighted different roles of the 20S proteasome in plant defense during virus infection, either indirectly through viral suppressor-mediated degradation of Argonaute proteins, affecting the RNA interference pathway, or directly through modulation of the proteolytic and RNase activity of the 20S proteasome, a component of the 20S proteasome, by viral proteins, affecting the levels of viral proteins and RNAs. Here we show that MG132, a cell permeable proteasomal inhibitor, caused an increase in papaya ringspot virus (PRSV accumulation in its natural host papaya (Carica papaya. We also show that the PRSV HcPro interacts with the papaya homologue of the Arabidopsis PAA (α1 subunit of the 20S proteasome, but not with the papaya homologue of Arabidopsis PAE (α5 subunit of the 20S proteasome, associated with the RNase activity, although the two 20S proteasome subunits interacted with each other. Mutated forms of PRSV HcPro showed that the conserved KITC54 motif in the N-terminal domain of HcPro was necessary for its binding to PAA. Co-agroinfiltration assays demonstrated that HcPro expression mimicked the action of MG132, and facilitated the accumulation of bothtotal ubiquitinated proteins and viral/non-viral exogenous RNA in Nicotiana benthamiana leaves. These effects were not observed by using an HcPro mutant (KITS54, which impaired the HcPro - PAA interaction. Thus, the PRSV HcPro interacts with a proteasomal subunit, inhibiting the action of the 20S proteasome, suggesting that HcPro might be crucial for modulating its catalytic activities in support of virus accumulation.

  19. Catalytic flash pyrolysis of oil-impregnated-wood and jatropha cake using sodium based catalysts

    NARCIS (Netherlands)

    Ali Imran, A.; Bramer, Eduard A.; Seshan, Kulathuiyer; Brem, Gerrit

    2016-01-01

    Catalytic pyrolysis of wood with impregnated vegetable oil was investigated and compared with catalytic pyrolysis of jatropha cake making use of sodium based catalysts to produce a high quality bio-oil. The catalytic pyrolysis was carried out in two modes: in-situ catalytic pyrolysis and post

  20. Crystal structure of the P pilus rod subunit PapA.

    Directory of Open Access Journals (Sweden)

    Denis Verger

    2007-05-01

    Full Text Available P pili are important adhesive fibres involved in kidney infection by uropathogenic Escherichia coli strains. P pili are assembled by the conserved chaperone-usher pathway, which involves the PapD chaperone and the PapC usher. During pilus assembly, subunits are incorporated into the growing fiber via the donor-strand exchange (DSE mechanism, whereby the chaperone's G1 beta-strand that complements the incomplete immunoglobulin-fold of each subunit is displaced by the N-terminal extension (Nte of an incoming subunit. P pili comprise a helical rod, a tip fibrillum, and an adhesin at the distal end. PapA is the rod subunit and is assembled into a superhelical right-handed structure. Here, we have solved the structure of a ternary complex of PapD bound to PapA through donor-strand complementation, itself bound to another PapA subunit through DSE. This structure provides insight into the structural basis of the DSE reaction involving this important pilus subunit. Using gel filtration chromatography and electron microscopy on a number of PapA Nte mutants, we establish that PapA differs in its mode of assembly compared with other Pap subunits, involving a much larger Nte that encompasses not only the DSE region of the Nte but also the region N-terminal to it.