site residues and catalytic activity

... arginyl residues 196, 213, 234 and 235 [9] Of theses residues, only Arg213 is in the vicinity of the active site of RTA In order to establish the role of arginyl residues around the active site ... affecting the activity of ricin A chain (Eur J Biochem 271) 161 magnitude It then appears that, in addition to catalytic site residues, a number of the Arg residues located around the active site cleft ... of either active site residues or residues in the vicinity of the substitution That the RTA N78S variant had no effect on activity, but the RTA N122A variant reduced catalytic activity over 30-fold...

Ngày tải lên: 19/02/2014, 12:20

... Ser16 and Ser127 residues acting in a proton relay system among His106, FMN and EPSP via a water molecule in the chorismate synthase active site (A) Stereorepresentation of the active site in ... oxidized FMN and EPSP (catalytically inactive ternary complex) has provided the first insight into the binding and relative orientation of the cofactor and the substrate in the active site of the ... amino acid residues, the active site of chorismate synthase features two strictly conserved (99.5% of 400 sequences aligned) serine residues located near the substrate on the opposite site of the...

Ngày tải lên: 07/03/2014, 05:20

... 4¢-phosphopantothenate binding residues Asn59, Ala179, Ala180 and Asp183 from one monomer and Arg55¢ from the adjacent monomer correspond to E coli CoaB residues Asn210, Ala275, Ala276, Asp279 and Arg206 A model ... (forward) 5¢-GCCAGTTTTGAATTCTGGAAAGCGC CTCG-3¢ and (reverse) 5¢-CGGGTCCAAGATCTTAA CGTCGATTTTTTTC-3¢ as primers (introduced EcoRI and BglII sites are underlined) and the purified chromosomal DNA as template ... and 450 nm Molecular mass information was obtained as described [6], determining the elution volumes of standard proteins and the void volume of the column The Superdex 200 PC 3.2/30 column and...

Ngày tải lên: 19/02/2014, 12:20

... L537W E542K and L537W E542R were constructed by site- directed mutagenesis aiming to combine the positive effects of the different single mutations on thermostability and catalytic activity Again, ... active site from the internal cavity of the homotetramer Concomitantly, Phe454 rotates and moves some A to ll the active site and pack against the FAD cofactor In the loop between b-strand B6 ... buffer (pH 6.5) at 60, 70 and 75 C, respectively, and by subsequent measurements of the enzyme activity (A) at various time points (t) using the standard ABTS assay and glucose as the substrate...

Ngày tải lên: 07/03/2014, 03:20

... (N92Q or N324D) and double N-glycosylation sites (N92Q ⁄ N324D) Asn residues in the two potential N-glycosylation sites (92NFT94 and 324NVT326) are substituted by Gln and ⁄ or Asp residues in the ... structures of wild-type cathepsin E and its active -site mutant Asp residues in the two active -site consensus motifs (98DTG100 and 273DTG275) are substituted by Ala residues in the mutant (B, C) HEK-293T ... A Recombinant cathepsin E and its mutants A B B C C Fig Pulse–chase analysis of the active -site mutant with Asp residues in the two active -site motifs changed to Ala residues (A) Schematic representation...

Ngày tải lên: 16/03/2014, 14:20

... substrate and therefore the hydride transfer steps are not rate determining in this reaction Site- directed mutagenesis In an effort to further understand the roles of the active site residues ... transfer steps will employ the same catalytic residues) In the first scenario, Lys204 acts as the catalytic base that deprotonates the C-6¢ hydroxyl, whereas Asn208 and an ordered water molecule serve ... hydrogen bond donors to the hydroxyl oxygen, and Thr118 and a ribose hydroxyl of NAD+ form hydrogen bonds with the ordered water The identity of the catalytic residues involved in hydrolysis of the...

Ngày tải lên: 23/03/2014, 12:20

... 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 ... replaced by leucine and a third variant with both residues exchanged to leucine In a fourth variant, we swapped the interacting residues in an attempt to restore the salt bridge and thus redesign ... details, see text) and differ only in some loop regions, especially around residues 109 and 137 The figure was prepared using the software PYMOL (http://www.pymol.org/) similar active sites as judged...

Ngày tải lên: 30/03/2014, 01:20

... combination of tandem MS and overall mass measurement allowed us to assign the 13852 Da peak to the b-subunit composed of residues Thr179–Gly315 and containing three oxidized methionine residues, as ... diagnostics and future therapeutic interventions Scand J Clin Laboratory Invest 53, 19–27 Geiger, T & Clarke, S (1987) Deamidation, isomerization, and racemization at asparaginyl and aspartyl residues ... [61] and amino acid frequencies observed in the sequences under analysis Site- to -site rate variation was modeled using a gamma distribution with eight gamma rate categories The above settings and...

Ngày tải lên: 30/03/2014, 15:20

... 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 ... easy access to the catalytic active sites, which would help to improve proton diffusion and mass transport Conclusions In this study, PtAg alloy nanoislands/graphene hybrid composites based on self-assembling ... surface of graphene sheets It is confirmed that PtAg alloy nanoislands/graphene hybrid composites own better catalytic activity and longer stabilization for methanol oxidation compared with traditional...

Ngày tải lên: 20/06/2014, 22:20

... negligible activity, suggesting that dimerization may be important for both stability and function [13,14] To establish the relationship between dimerization and catalytic activity, several site- directed ... residues showing critical hydrogen bonds at the dimer interface The residues in green are from subunit B and those in cyan are from subunit A The active site residues of P falciparum, yeast and ... hydrogen bonds between K12 and the side chains of N10 and Q64, which maintain the unusual Ramachandran angles for the K12 residue, and a Ramachandran scatter plot for the K12 residues in 21 TIM structures...

Ngày tải lên: 18/02/2014, 11:20

... are designated with the suffix ‘p’) and a catalytic domain (Ala1-Pro364; residues in the mature catalytic domain are numbered without a suffix where unambiguous, and with the suffix ‘e’ otherwise) ... 38-kDa and 19-kDa proteins were mixed and subjected to nondenaturing PAGE, these proteins comigrated with each other, showing a broad protein band that differed from the respective original bands and ... time-dependent enhancement of the 57-kDa band with a concomitant diminution of the 38-kDa and 19-kDa bands, as analyzed by SDS ⁄ PAGE (Fig 3A) The 38-kDa and 19-kDa bands did not disappear completely...

Ngày tải lên: 19/02/2014, 07:20

... Abcb1a, six single -site mutants (E552D, N and A, and E1197D, N and A,) and three double-mutants (E552Q ⁄ E1197Q, E552Q ⁄ K1072R, K429R ⁄ E1197Q) The ATPase activity, binding affinity and trapping properties ... the catalytic domain, composed of an ABC (ABCb) and a RecA-like subdomain, and contains the nucleotide-binding site; the second is the helical domain (ABCa), which interacts with the TMD and ... catalytic residue mutants of the Walker A and Walker B motifs and of the ICs (K429R, K1072R, D551N, D1196N, E552Q and E1197Q), which severely affect the catalytic activity of mouse Abcb1a but have little...

Ngày tải lên: 07/03/2014, 06:20

... of H2O and 6-APA with the acyl-enzyme Mutating the residues that are closer to the active -site serine, bF24 and aF146, yielded mutants that were changed with respect to both activity and interaction ... Netherlands) RESULTS Activity of site- directed mutants for NIPAB Three phenylalanines in the acyl-binding site of PA of E coli, bF24, bF57 and aF146, were investigated by sitedirected mutagenesis ... shape and volume of the acyl binding pocket and thereby alter the binding mode and affinity of the enzyme for PAA and derivatives thereof, while maintaining the hydrophobicity of the binding site...

Ngày tải lên: 17/03/2014, 23:20

... hypoxia on CytOX activity, mitochondrial heme aa3 content and TN (s)1) in macrophages and PC12 cells CytOX activity in submitochondrial particles (SMP) from standard (141 Torr O2) and hypoxia (1 ... dithiothreitol, 0.1% Chaps and 150 mM NaCl and protease inhibitors [5 lgÆmL)1 pepstatin A, lgÆmL)1 aprotinin, and mM phenylmethanesulfonyl fluoride]) and lysed by three cycles of freezing and thawing in liquid ... encoded catalytic subunits I and II, and the nuclear genome encoded subunits, IV, Vb and VIIa The mammalian CytOX subunit IV is a homolog of the yeast subunit V, with the latter expressed in an O2 and...

Ngày tải lên: 20/02/2014, 23:20

... mutations from both the stability and activity mutants, and demonstrated a significant improvement in both stability and catalytic activity (Fig 1) As such, the activity and stability mutation combinations ... the catalytic lysine residue 6190 70 Temperature (ºC) Relative activity (%) Specific activity (units·mg–1) Temperature (ºC) 10 11 Fig Effect of temperature and pH on stability and catalytic activity ... stability and catalytic activity of S toebii TPL Materials and methods Materials Sodium pyruvate and PLP were obtained from Musashino Shoji (Tokyo, Japan) and Fluka (Seelze, Germany), respectively, and...

Ngày tải lên: 07/03/2014, 00:20

... The critical active site residues 197, 256, and 338, as well as the catalytic triad (Cys164, His303, and Asn336) and the gatekeeper Phes (Phe215 and Phe265) are highlighted Residues for the CoA ... almost identical CoA binding site and the catalytic triad of Cys164, His303, and Asn336 (numbering in M sativa CHS) (Fig 2) Furthermore, most of the active site residues including Met137, Gly211, ... active site of the Cys-His-Asn catalytic triad [1,2] The simple steric modulation of the active site cavity by the three residues, Ala197, Leu256, and Thr338, is crucial for the remarkable catalytic...

Ngày tải lên: 16/03/2014, 14:20

... well investigated We have purified and characterized an NAD+-dependent SSADH from bovine brain [2], and found that the arginine residues are connected with catalytic activity of the enzyme [13] Recently, ... Bovine brain succinic semialdehyde dehydrogenase: purification, kinetics and reactivity of lysyl residues connected with catalytic activity Mol Cells 5, 611–617 Ryzlak, M.T & Pietruszko, R (1988) Human ... respectively, as shown in Fig Amino acid analysis and protein sequencing The amino acid analysis and sequence of peptides I and II were examined and the observed sequences were found to be in reasonable...

Ngày tải lên: 16/03/2014, 18:20

... determined using a continuous assay and synthetic peptide substrates Wild-type P ⁄ CAF has kcat and KM values of 12 min)1 and 53 lm with the H3 peptide and 0.29 min)1 and 194 lm with the H4 peptide, ... mutations to thermostability, and constructed the L503P, D601G and D639E mutants by site- directed mutagenesis DSC of the single mutants showed that D601G, V582A and D639E made a large contribution ... initial activity is lost in min; T50AcCo, temperature at which half of the initial activity is lost in in the presence of acetyl-CoA; t1 ⁄ 2, 48 °C, activity half-life at 48 °C Errors for Tm and...

Ngày tải lên: 23/03/2014, 06:20

... Standard dilutions of commercial BSA were used to generate a standard curve pH of maximal activity, enzyme kinetic assays and inhibition studies The pH of maximal activity for wild-type HAP and ... with three determinations each and standard deviation Kinetic characterization and molecular modeling of both the H34A and S37A mutants suggests that although His34 and Ser37 were not essential ... Asp214 and pepstatin A In conclusion, a study was conducted to investigate residues previously proposed by other research groups as essential to catalytic activity The model reported by Bjelic and...

Ngày tải lên: 23/03/2014, 07:20

... fluoride and TLCK, respectively TPCK had, however, no effect on catalytic activity Incubation of purified (His)6PNAE wild-type enzyme in the presence of Hg+2 resulted in complete loss of catalytic activity, ... reduce the activity of (His)6PNAE Site- directed mutagenesis In this study, we have produced wild-type (His)6PNAE and 10 muteins of it Four of six cysteine residues in positions 20, 132, 170 and 257 ... SDS/PAGE and Coomassie-blue staining (Fig 2) The degree of enzyme purity among the active muteins and the wild-type preparations was comparable Enzyme activity and kinetics The enzyme activity...

Ngày tải lên: 24/03/2014, 04:21