Báo cáo khoa học: Spectroscopic and kinetic properties of the horseradish peroxidase mutant T171S Evidence for selective effects on the reduced state of the enzyme potx

... Spectroscopic and kinetic properties of the horseradish peroxidase mutant T171S Evidence for selective effects on the reduced state of the enzyme Barry D. Howes1, ... and speciﬁcto the reduced state of the enzyme. The Fe(II) state of the enzyme has features in common with both the Phe221Met mutant and Ca-depleted proteins whilst the Fe(III) state is essentially ... selective effects that are mediatedexclusively on the reduced state of the enzyme. Wehypothesize that this residue imposes a degree of rigid-ity to the structure of the reduced state of class IIIperoxidases.Results...

Báo cáo khoa học: Cholinoceptive and cholinergic properties of cardiomyocytes involving an ampliﬁcation mechanism for vagal efferent effects in sparsely innervated ventricular myocardium ppt

... of the beneﬁcial effects of ACh has beenchallenged by accumulating evidence of the sparseness of cholinergic innervation of the ventricular myo-cardium, except for the specialized conduction ... intracellular pathways for ACh production in cardiomyocytes. Second, wedetermined the intracellular concentrations and loca-tions of ACh. Third, we examined the effects of donepezil on the intracellular ... investigation conformed to the Guide for the Care and Use of Laboratory Animals published by the US NationalInstitutes of Health. Care and use of the animals were alsoin strict accordance with the guiding...

Báo cáo khoa học: Allosteric and binding properties of Asp1–Glu382 truncated recombinant human serum albumin – an optical and NMR spectroscopic investigation pot

... to the heme[23,24]. The conformational adaptability of HSA involvesmore than the immediate vicinity of the binding site(s),affecting both the structure and the ligand-binding properties of the ... þ36c2D2s2vð11Þwhere N is the molar concentration of Fe(III)heme, q is the number of water molecules coordinated to the metal ion,r is the average distance between the metal ion and the protons of the water ... difference atsaturating ligand concentration, Kdis the dissociationequilibrium constant for ligand–protein complexformation, [Lt] is the total concentration of the variableligand [Fe(III)heme,...

Báo cáo khoa học: Thermodynamic and kinetic analysis of the isolated FAD domain of rat neuronal nitric oxide synthase altered in the region of the FAD shielding residue Phe1395 docx

... probing the thermodynamic and kinetic consequences of these mutations. We have studied the thermodynamic and kinetic properties of the isolatedFAD domain of rat nNOS and three mutant forms. The isolated ... the thermodynamic properties of the FAD and also theirconsequences on the kinetics of FAD reduction. The thermodynamic properties of the wild-type and mutant nNOS FAD domains are compared with the potentials ... multiple spectroscopic signalsfrom additional cofactors and conformational effects induced by CaM binding. Thus, for the ﬁrst time we areable to report the effects of these mutations on the thermodynamic...

Báo cáo khoa học: Human anionic trypsinogen Properties of autocatalytic activation and degradation and implications in pancreatic diseases potx

... pHselectively inhibited activation of anionic trypsinogen.Under both conditions, the concentration of cationictrypsinogen seemed to determine the rate of autoactivation and the final levels of ... demonstrated. In these conditions, the pro-portion of anionic and cationic isoforms becomes reversed, and anionic trypsinogen dominates pancreatic secretions. Inacute pancreatitis, the ratio of ... autoactivation of anionic trypsinogen. In mixtures of cationic and anionictrypsinogen, an increase in the proportion of the anionicproenzyme had no significant effect on the levels of trypsingenerated...

Báo cáo khoa học: Spectroscopic and DNA-binding characterization of the isolated heme-bound basic helix–loop–helix-PAS-A domain of neuronal PAS protein 2 (NPAS2), a transcription activator protein associated with circadian rhythms docx

... 530 and 559 nm, and those of the Fe(II)–CO complex were at 422, 538 and 566 nm. On the other hand, optical absorptionspectra of the Fe(III), Fe(II) and Fe(II)–CO complexes of the PAS-A domain of ... that the rate constant was similarto those of other heme proteins (Table 4). On the basis of these association and dissociation rate constants, weestimated the heme dissociation equilibrium constant(Kd). ... determined the rate constant for the dissoci-ation of heme from the holo-bHLH-PAS-A domain of NPAS2 by mixing it with an excess of the H64Y ⁄ V68Fapomyoglobin mutant. The reaction was monitoredby...

Tài liệu Báo cáo khoa học: Functional and structural analyses of N-acylsulfonamidelinked dinucleoside inhibitors of RNase A ppt

... alternativeconformations. The pseudorotation angles for the uridine of N-acyl-sulfonamide 7 were found in both the C3¢-endo (N)conformation and the O4¢-endo conformation, whereas the C3¢-endo conformation ... hydrogen bonds with the enzyme, and O2¢ forms two additional hydrogen bondsin each of its conformations. Thus, in either observedconformation of N-acylsulfonamide 7, there are a total of four ... structure of N-acylsulfonamide 7 was reﬁned with full occupancy,except for the alternative conformations observed for the N-acylsulfonamidyl group and the addition of O2¢. The value of the nucleoside...

Tài liệu Báo cáo khoa học: Active and regulatory sites of cytosolic 5¢-nucleotidase doc

... that the enzyme has at least three effector sites, one for ATP, one for ADP and one for BPG [5,12]. On the basis of the results obtained from crystallization of atruncated form of cN-II [11], we constructed ... binding of adenine (F127E and M436W) had no effect on the functional characteristics of the enzyme, except for anincrease in the K50 for Ap4A for mutant M436W. The mutations did not alter the ... location of the interaction sites for the activators and inhibitors, the relationship betweenactivity and enzyme oligomerization state, and, ﬁnally, the amino acid residue(s) responsible for phospho-transferase...

Tài liệu Báo cáo khoa học: Structural and functional studies of the human phosphoribosyltransferase domain containing protein 1 docx

... confor-mation change, then allowing the purine base to bind inaccordance with the mechanism of human HPRT[19,25]. This conclusion can be made based on the lack of thermal shifts when only the ... result of the high concentration of Ca2+present in the crys-tallization buffer. The geometry is consistent with aCa2+ion coordinated by Glu141, Asp142, 2¢ and 3¢OH of the ribose and three ... TCEP]. The purity of the protein was estimated on SDS ⁄ PAGE. The protein concentration was measured using Bradford reagent[27]. A similar protocol was used for the expression and puriﬁcation of...

Tài liệu Báo cáo khoa học: Isolation and molecular characterization of a novel D-hydantoinase from Jannaschia sp. CCS1 docx

... at a ﬁnal concentration of 1 mm.Bacterial strains and culture conditionsE. coli strain DH5a was used for the cloning and ampliﬁca-tion of all constructed plasmids. Overexpression of targetgenes ... ones (Glu and Asp), while mutation of Phe63 into other amino acidsallowed the enzyme to retain similar activity. Leu92 isone of the major constituents of the hydrophobic lids of the substrate ... 56 kDa, which isconsistent with the calculated mass of the His-taggedtranslational product of the corresponding hyd genes. The monomer size of HYDBpwas similar to that of other hydantoinases,...

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