Báo cáo khoa học: Probing the determinants of coenzyme speciﬁcity in Peptostreptococcus asaccharolyticus glutamate dehydrogenase by site-directed mutagenesis potx

... examined the possi-bility of altering coenzyme specificity of the Peptostreptococcus enzyme,and, more specifically, the role of residue 243 and neighbouring residues in coenzyme binding, by introducing ... Probing the determinants of coenzyme specificity in Peptostreptococcus asaccharolyticus glutamate dehydrogenase by site-directed mutagenesis John B. Carrigan and Paul C. EngelSchool of Biomolecular ... in the absence of the other substrate. In the presence of oxoglutarate,however, coenzyme binding was tighter and thereforemeasurable and, in particular, gave measurable Kdvalues for binding...

Báo cáo khoa học: Probing the determinants of substrate speciﬁcity of a feruloyl esterase, AnFaeA, from Aspergillus niger doc

... chain of the FA. The importance of the interaction between an aromatic tyrosine and the phenolic ring of the substrate is consistent with the biochemical speciﬁcity of this enzyme [4,24]. The ... resulting from the disposition of the equatorial and axial hydroxyls toone side of the pyranose ring of a sugar monomer,aligns itself upon binding with the aromatic ring face of the amino acid ... direct stacking interaction with the phenolic ring of FA, instead contributing to the hydro-phobic environment by forming a small cavity with aleucine residue on one side of the binding depression[20].The...

Tài liệu Báo cáo khoa học: Seeking the determinants of the elusive functions of Sco proteins pptx

... trans-membrane helix anchoring the protein to the innermembrane of mitochondria [27]. Therefore, the N-ter-minal segment (containing the residues protruding into the mitochondrial matrix, the transmembrane ... function of the CXXXCmotif of human Sco proteins could therefore be impli-cated not only in the maturation of the CuAsite of Cox2 but also in the maintenance of cellular copperhomeostasis. The involvement ... proteins in kinetoplasts and land plants aswell. In particular, determining the function of the duplicated plant proteins would be especially interest-ing, as in all plants one of the two proteins...

Báo cáo khoa học: Probing the mechanism of the bifunctional enzyme ketol-acid reductoisomerase by site-directed mutagenesis of the active site pot

... when the crystal structure of the spinach enzyme was deter-mined, ﬁrst in the presence of the inhibitor IpOHA [8]and later with product bound in the active site [9].There are several interesting ... both valine and leucine. The thirdbranched-chain amino acid, isoleucine, is produced in a pathway that parallels that of valine, employing the same series of enzymes, with KARI catalyzing the conversion ... supported by the observation thatmutating H132 to glutamine has by far the greatesteffect on the Kmfor NADPH, increasing it by 28-fold(Table 4).Several of the mutations leave the reductase...

Báo cáo khoa học: Probing the access of protons to the K pathway in the Paracoccus denitriﬁcans cytochrome c oxidase pdf

... given by electrostatic calculations indicating that the redox state of the binuclear center in uences the protonation state of a glutamate residue positioned at the cytoplasmic end of the second ... bandwidth of the contribution at  1718 cm)1indicates thatresidues close to the surface, or in the vicinity of sev-eral water molecules are involved here. Comparing the spectra of the E78IIQ ... certain degree of ﬂexibility in the design of indi-vidual mechanistic steps.Experimental procedures Mutagenesis and cloning Site-directed mutations of subunit II were introduced with the Altered...

Báo cáo khoa học: "Examining the Role of Linguistic Knowledge Sources in the Automatic Identification and Classification of Reviews" doc

... documents and find that the fea-ture vectors corresponding to some of these docu-ments (particularly the short ones) have all zeroes in them. In other words, none of the bigrams from the training set ... available.612Finally, previous work has also investigated fea-tures that do not fall into any of the above cate-gories. For instance, instead of representing the polarity of a term using a binary value, ... cap-turing two different situations, one in which the author himself likes the movie, and in the other, the author’s cousin likes the movie. The over-generalization resulting from these “stemmed”...

Báo cáo khoa học: Structural origins for selectivity and speciﬁcity in an engineered bacterial repressor–inducer pair pdf

... respect to the positioning of the ligands and the conformations of the residues lining the bindingsite (Table 2). In an initial comparison of the ligandpositions of tetracycline, dox and atc in TetR, ... shown in grey and blue). The stereo represen-tation shows that the binding position of the ligands and the orientations of the side chains lining the binding sites are highly conserved in the ... comprises the dimer interface. The two effector-binding sites present in the dimer are identical and,because the binding sites are located within the proteininterface, each binding site is lined by...

Tài liệu Báo cáo khoa học: Probing the molecular determinants of aniline dioxygenase substrate speciﬁcity by saturation mutagenesis docx

... was determinedon the basis of the possible binding sites identiﬁed by the Site Finder function in moe, as well as the relativeposition of the indole substrate in the crystal structure of naphthalene ... probe the residues determining the activity as well as the sub-strate speciﬁcity of AtdA, using molecular modelingand saturation mutagenesis of the substrate-bindingpocket residues in AtdA3. The ... position in the bind-ing pocket of the WT enzyme, the side chain of V205would come within 2.74 A˚ of the isopropyl side chain of 2IPA (Fig. 3C). This could result in a steric clashthat forces the...

Báo cáo khoa học: Structures of type B ribose 5-phosphate isomerase from Trypanosoma cruzi shed light on the determinants of sugar speciﬁcity in the structural family ppt

... 5 min, the reaction was initiated by the addition of 10 lL of enzyme solution (0.83 mgÆmL)1).After 3 min, the reaction was stopped by the addition of 100 lL of concentrated HCl; after mixing, ... contacts with their equiv-alents in the other subunit of the second dimer(Fig. 4A). In the case of P21212(TcRpiB-R5P), the four molecules in the asymmetric unit represent the tetramer. The two ... Arg141¢. The other end of the substrate points into a deep pocket in the enzyme.Moving along the ligand from the phosphate, O4 inter-acts with His102¢ and a water molecule that is in turnwithin...

Báo cáo khoa học: Probing the catalytic potential of the hamster arylamine N-acetyltransferase 2 catalytic triad by site-directed mutagenesis of the proximal conserved residue, Tyr190 pot

... The reaction rate was deter-mined at 25 °C by measuring the linear increase in absor-bance at 400 nm during the initial 5 min. Controlexperiments were carried out in the absence of NAT2. The slope ... centroid of the His107 imidazole ring and the planes of the two ringsystems intersect at an angle of $ 30°, Tyr190 andHis107 interact by a common aromatic stacking inter-action. To gain insight into ... 1%). The rate of the reaction was determined by monitoring the linearincrease in absorbance at 400 nm because of the formation of PNP. The speciﬁc activity was calculated and expressed in lmÆmg)1Æmin)1.Presteady-state...

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