and intramolecular electron and proton transfer and catalytic mechanism

Báo cáo khoa học: Ribonuclease H: molecular diversities, substrate binding domains, and catalytic mechanism of the prokaryotic enzymes ppt

Ngày tải lên : 30/03/2014, 02:20

... H with the substrate and metal ions (yellow) The positions of the RNA strand of the substrate with the scissile phosphate group between R()1) and R(0) and two metal ions A and B are also shown ... Asp10, Glu48, Asp70 and Asp134 for Eco-RNase HI, Asp71, Glu109, Asp132, and Asp192 for Bha-RNase HI, Asp145, Glu186, Asp210 and Asp274 for human RNase H1, and Asp443, Glu478, Asp498 and Asp549 for ... Eco-RNase HI) and the backbone atoms of Cys148, Ser150, Asn151 and Met212 (Cys13, Gly15, Asn16 and Gln72 for Eco-RNase HI) Similar contacts are observed between Bha-RNase HI and the RNA strand of the...

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Tài liệu Báo cáo khoa học: Proton transfer in the oxidative half-reaction of pentaerythritol tetranitrate reductase Structure of the reduced enzyme-progesterone complex and the roles of residues Tyr186, His181 and His184 pdf

Ngày tải lên : 20/02/2014, 02:21

... C1 and C2; the double bond between C4 and C5 is not susceptible to reduction, and thus progesterone and related steroids (e.g 4-androstene3,17-dione), which lack a double bond between C1 and ... involved in ligand binding and counterpart residues in related enzymes and also the location of the tyrosine residue implicated as proton donor in OYE B constant for enzyme-ligand complexes, ... Proton transfer in PETN reductase Table Kinetic parameters for the reductive and oxidative half-reactions of wild-type, H181A, H184A and Y186F PETN reductases Kinetic data are shown in Figs and...

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Báo cáo khoa học: Replacement of two invariant serine residues in chorismate synthase provides evidence that a proton relay system is essential for intermediate formation and catalytic activity docx

Ngày tải lên : 07/03/2014, 05:20

... catalysis by ‘separation’ of an electron and a proton, both of which are derived from the reduced protonated ﬂavin in a proton- coupled electron transfer step The electron is donated to the substrate ... al Proton relay system in chorismate synthase H2 C H N NH His106 N N H2 C NH His106 N H O N N O N H NH Electron transfer N H O NH H CO2 – O O O OH Scheme Proposed proton relay system Such a proton ... mediated by wat 1, wat 2, wat and the carboxyl group of EPSP, which serve as a proton translocation system in the active site (see Fig 1B and Scheme 2) Interestingly, the proton on the N(1)–C(2)=O...

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Báo cáo toán học: "OXIDATIVE PHOSPHORYLATION: Kinetic and Thermodynamic Correlation between Electron Flow, Proton Translocation, Oxygen Consumption and ATP Synthesis under Close to In Vivo Concentrations of Oxygen" docx

Ngày tải lên : 08/08/2014, 17:20

... Coupling of phosphorylation to electron and hydrogen transfer by a chemiosmotic type of mechanism Nature 1961; 191: 144-8 Brand MD The stoichiometry of proton pumping and ATP synthesis in mitochondria ... kinetic and thermodynamic correlation between O2 consumption and ATP synthesis only occur when the mitochondrial membrane is maximally reduced and/ or protonated II The rates of O2 consumption and ... energy of electron flow is essential not only for the binding and release of substrates and products to and from the ATP synthase but most importantly for the synthesis of ATP from ADP and Pi 0.8...

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Tài liệu Báo cáo khoa học: Tryptophan tryptophylquinone cofactor biogenesis in the aromatic amine dehydrogenase of Alcaligenes faecalis Cofactor assembly and catalytic properties of recombinant enzyme expressed in Paracoccus denitriﬁcans pptx

Ngày tải lên : 19/02/2014, 07:20

... orf-4 and hemE) all putatively transcribed in the same direction [7] The second and ﬁfth genes (aauA and aauB) encode the large and small subunits of AADH, respectively The genes aauD and aauE ... cells and media The bacterial strains and plasmids used in this study are listed in Table For strain stocks and DNA isolation, E coli and A faecalis were cultured with Luria–Bertani media at 37 and ... coupling through Val-344 and Tyr-442 of trimethylamine dehydrogenase in electron transfer reactions with ferricenium ions and electron transferring ﬂavoprotein Biochemistry 39, 9188–9200 FEBS Journal...

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Tài liệu Báo cáo khoa học: Critical roles of Asp40 at the haem proximal side of haem-regulated phosphodiesterase from Escherichia coli in redox potential, auto-oxidation and catalytic control doc

Ngày tải lên : 19/02/2014, 16:20

... structure and catalytic mechanism of Ec DOS Cyanide-bound Fe(III) complexes of the Asp40 mutants displayed optical absorption spectra containing a sharp Soret peak at 421 nm and a broad visible band ... auto-oxidation rates and catalytic activities of Ec DOS Breakage of the salt bridge between Asp40 and Arg85, and the hydrogen bond network consisting of Asp40, two water molecules and His77, appear ... His77, two water molecules and Asp40 should function in regulating the electronic state affecting the redox potential and autooxidation rate A signal transduction mechanism for the PAS domain...

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Tài liệu Báo cáo khoa học: Unraveling the catalytic mechanism of lactoperoxidase and myeloperoxidase A reﬂection on some controversial features Elena Ghibaudi and Enzo Laurenti docx

Ngày tải lên : 20/02/2014, 02:21

... MPO, LPO and their intermediates The absorption spectrum of MPO is characterized by an intense Soret peak at kmax ¼ 430 nm and weaker bands at 570, 620 and 690 nm, whereas at 370 nm and 496 nm, ... myelo- and lactoperoxidase mechanisms (Eur J Biochem 270) 4409 The observed effect of pH on the band at 628 nm of Cpd II [1,24] might reﬂect protonation of an amino acid found in the heme crevice and ... rapidly inactivates LPO and generates Cpd III (with bands at 424, 550 and 588 nm) (Table 2) In contrast to MPO, LPO Cpd III spectral pattern is clearly distinct from that of Cpd II and can be easily...

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Báo cáo " Study on the characteristics and catalytic properties of Pt/SBA-15 in the selective oxidation of D-Glucose " potx

Ngày tải lên : 05/03/2014, 11:21

... Synthesis and characterization of Bimetallic Pt-Au clusterderived catalyst Catalysis Today, 125, 269-274, 2006 [5] A.Corma and Hermenegilldo Garcia Nanoparticles and catalysis Wiley-VCH Verlag GmbH and ... Advanced Institute of Science and Technology) N2 adsorptiondesorption method and Energy Dispersive Xray Spectroscopy (EDX) were measured on Micromerictics ASAP 2010 and Varian Vista Ax apparatuses, ... (RID) Results and discussion 3.1 Characteristics of SBA-15 material The low-angle XRD patterns of SBA-15 at different aging time (24, 48 and 72 hours) as showed in Fig.1 are similar and all show...

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Báo cáo khoa học: Ibuprofen binding to secondary sites allosterically modulates the spectroscopic and catalytic properties of human serum heme–albumin doc

Ngày tải lên : 06/03/2014, 01:20

... high-afnity and low-afnity sites of tHSAheme-Fe(III) and HSAheme-Fe(III) [represented by a and (1 a), respectively, in Eqn (1)] are 0.18 and 0.82, and 0.14 and 0.86, respectively (Table 1) Effect of ibuprofen ... (1971) Hemoglobin and Myoglobin in their Reactions with Ligands North Holland Publishing Co., Amsterdam and London Goldstein S, Lind J & Merenyi G (2005) Chemistry of peroxynitrites and peroxynitrates ... nal ibuprofen concentration ranged between 1.0 ã 10)6 and 1.0 ã 10)2 m Peroxynitrite was synthesized from KO2 and NO or from HNO2 and H2O2, and stored in small aliquots at )80.0 C [29,30] The peroxynitrite...

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Báo cáo khoa học: Improving thermostability and catalytic activity of pyranose 2-oxidase from Trametes multicolor by rational and semi-rational design pdf

Ngày tải lên : 07/03/2014, 03:20

... alternative electron acceptors of P2Ox [i.e the one -electron acceptor substrate ferricenium ion (Fc+) and the two -electron acceptor substrate 1,4benzoquinone] using both d-glucose and d-galactose ... absence of electron- donor monosaccharide substrate or electronacceptor substrate, the substrate loop in the E542K and L537G variants is open and slightly disordered, as indicated by partly weak electron ... oxidative half-reaction, in which electrons are transferred to an acceptor P2Ox not only can transfer these electrons to oxygen, but also to a range of other electron acceptors, including substituted...

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Báo cáo khoa học: The stop transfer sequence of the human UDPglucuronosyltransferase 1A determines localization to the endoplasmic reticulum by both static retention and retrieval mechanisms docx

Ngày tải lên : 07/03/2014, 16:20

... from the properties of the TMD and its interaction with the membranes It has been demonstrated that TMD of the yeast Sec12p and UBC6 (ubiquitin-conjugating enzyme 6) and of the rabbit cytochrome ... from the ER and arrival at the plasma membrane [8,9] Human UDP-glucuronosyltransferase 1As (UGT1A, EC 2.4.1.17) are members of UGT superfamily that plays a key role in the inactivation and elimination ... that the dilysine residues at critical positions )3 and )5 were positioned at )14 and )16 (Fig 1) The mutants were stably expressed in HeLa cells and their sensitivity to endoglycosidase treatment...

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Báo cáo khoa học: Characterization of structural and catalytic differences in rat intestinal alkaline phosphatase isozymes pdf

Ngày tải lên : 07/03/2014, 17:20

... Distances were calculated between OE1 and the metal in hPLAP, and between OE2 and the metal in the rIAPs The metal position was based on the M3 position of hPLAP rIAP-I and rIAP-II are expressed in the ... blotting (Fig 3) In the jejunum, one rIAP band, with an apparent molecular mass of 70 kDa, was present, but two bands of 88 kDa and 75 kDa were detected as rIAP-II and rIAP-I in the duodenum The molecular ... placental alkaline phosphatase (hPLAP) sequence number H153 and H317 in hPLAP are homologous to D153 and K328 in Escherichia coli and to H149 and H316, respectively, in shrimp AP The alkaline phosphatase...

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Báo cáo khoa học: The lactate dehydrogenases encoded by the ldh and ldhB genes in Lactococcus lactis exhibit distinct regulation and catalytic properties ) comparative modeling to probe the molecular basis pdf

Ngày tải lên : 16/03/2014, 05:20

... measured and compared with those of the ldh-encoded enzyme (LDH) In addition, the mechanism for the activation of the alternative gene was elucidated and structural models were generated for LDH and ... kinetic parameters (A) and relative activity (B) of LDHB and LDH puriﬁed from L lactis FI9078 and MG1363, respectively Assays were performed in 100 mM Mes ⁄ KOH at the mentioned pH and 30 °C All components ... residues (His171) from neighboring monomers (A and C; B and D), whose protonation will certainly affect afﬁnity for the negatively charged Fru(1,6)P2 The proton equilibrium calculations show that,...

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Báo cáo khoa học: Identiﬁcation and characterization of important residues in the catalytic mechanism of CMP-Neu5Ac synthetase from Neisseria meningitidis potx

Ngày tải lên : 22/03/2014, 21:21

... reaction, and by comparing the kinetic parameters determined for the alanine mutants we were able to identify key catalytic residues and put forward a revised catalytic mechanism for CNS Results and ... hydrogen-bonding network and metal-binding residues; and requires Asp211 and Asp209 to bind the catalytic Mg2+ ion Our results also lend weight to a recently suggested mechanism for the L-CKS ... Mg2+ ion and a hydroxide ion were apparent [11,13] The Mg2+ ion was held in place by the bound CTP molecule and residues Asp225 and Asp98 We propose that these residues correspond to Asp209 and Asp211...

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Báo cáo Y học: Puriﬁcation and catalytic properties of a CO-oxidizing:H2-evolving enzyme complex from Carboxydothermus hydrogenoformans doc

Ngày tải lên : 23/03/2014, 21:20

... designated cooF1 and cooSI cooFI encodes an electron transfer protein predicted to ligate four [4Fe)4S] clusters cooSI encodes the Ni- and Fe-containing catalytic subunit of CO dehydrogenase A catalytically ... Nikon) and protein bands were quantiﬁed using the IMAGEQUANT software (Molecular Dynamics) Alternatively, Coomassie-stained protein bands were excised from SDS gels In general protein bands from ... amino-terminal sequences of the 89- and 62-kDa protein bands were found to be identical Since the 89-kDa band was not observed in boiled samples, this may indicate that this protein band is the dimer of the...

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Báo cáo khoa học: A single intersubunit salt bridge affects oligomerization and catalytic activity in a bacterial quinone reductase pptx

Ngày tải lên : 30/03/2014, 01:20

... presence of NADPH as the electron donor and 2-hydroxy-p-naphthoquinone as electron acceptor The family of parallel lines obtained from data analysis indicates a ping-pong bi-bi mechanism, where both ... Steady-state and rapid reaction parameters for wild-type YhdA and protein variants Turnover measurements were carried out with NADPH and oxygen as substrates The rate of reduction and oxidation ... a search model and were further reﬁned using the software phenix [27] Model building and ﬁtting steps involved the graphics software coot [28] using rA-weighted 2Fo–Fc and Fo–Fc electron density...

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Báo cáo khoa học: Expression, puriﬁcation and catalytic activity of Lupinus luteus asparagine b-amidohydrolase and its Escherichia coli homolog potx

Ngày tải lên : 30/03/2014, 15:20

... lateral gene transfer has played an important role between the Archaea and Cyanobacteria The branch of aspartylglucosaminidases is clearly separated and consists of two groups: bacterial and eukaryotic ... identiﬁcation of Thr179 (and its Thr193 analog in LlA) as the catalytic nucleophile and the classiﬁcation of both enzymes as Ntn-hydrolases The kinetic experiments demonstrate that LlA and EcAIII have ... and asparagine result in unexpected covalent inhibtions and suggests an unusual catalytic triad ThrTyr-Glu Biochemistry 39, 1199–1204 10 Sugimoto, H., Odani, S & Yamashita, S (1998) Cloning and...

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Báo cáo khoa học: Modeled ligand-protein complexes elucidate the origin of substrate speciﬁcity and provide insight into catalytic mechanisms of phenylalanine hydroxylase and tyrosine hydroxylase pptx

Ngày tải lên : 31/03/2014, 07:20

... Modeled ligand–protein complexes of PAH and TH (Eur J Biochem 270) 1067 energies The total electric charge was +6 for 5pah and )16 for 2toh, as 2toh comprises the catalytic core domain and the tetramerization ... ternary complex of the catalytic domain of human phenylalanine hydroxylase with tetrahydrobiopterin and 3-(2thienyl)-L-alanine, and its implications for the mechanism of catalysis and substrate activation ... the catalytic iron [16–18] Despite the similarities between TH and PAH regarding the structure of the active site and the catalytic mechanism, there is one striking difference: TH accepts also...

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Báo cáo hóa học: " Shape-tailoring and catalytic function of anisotropic gold nanostructures" doc

Ngày tải lên : 20/06/2014, 22:20

... 10, and 25 wt.% concentrations of detergent; and mM and wt.% concentrations of Au precursor and detergent, respectively (Table 1) Transmission electron microscopy (TEM) image (0.4 mM Au salt and ... azacryptand and their applications in SERS and catalysis J Colloid Interface Sci 2007, 316:476-481 doi:10.1186/1556-276X-6-547 Cite this article as: Premkumar et al.: Shape-tailoring and catalytic ... 2.7 used for the synthesis of triangle and spherical nanoparticles, and the final concentration between the Au precursor and detergent was maintained at mM and wt %, respectively Interestingly,...

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Báo cáo hóa học: " Preparation of Pt Ag alloy nanoisland/graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation" potx

Ngày tải lên : 20/06/2014, 22:20

... nanoisland/ graphene hybrid composites and its high stability and catalytic activity in methanol electro-oxidation Nanoscale Research Letters 2011 6:551 Submit your manuscript to a journal and beneﬁt ... density, the ease of handling a liquid, low operating temperature, and their possible applications to micro-fuel cells Electrocatalytic materials restricted the performance and application of DMFCs ... only for the catalyst surface available for charge transfer, but also includes the access of a conductive path to transfer the electrons to and from the electrode surface Hydrogen adsorption/...

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