Electrostatic Influences on the Kinetics of the Reactions of Lobster Metallothioneins with the Electrophilic Disulfides 2,2'-Dithiodipyridine (PySSPy) and 5,5'-Dithiobis(2-nitrobenzoic acid) (ESSE)

1995 ◽  
Vol 34 (17) ◽  
pp. 4477-4483 ◽  
Author(s):  
Zhiwu Zhu ◽  
David H. Petering ◽  
C. Frank Shaw
Keyword(s):  
Nitrobenzoic Acid ◽  
Kinetics Of

Comparison of the structure and function of ribulosebisphosphate carboxylase–oxygenase from a cold-hardy and nonhardy potato species

1981 ◽  
Vol 59 (4) ◽  
pp. 280-289 ◽  
Author(s):  
Norman P. A. Huner ◽  
Jiwan P. Palta ◽  
Paul H. Li ◽  
John V. Carter
Keyword(s):  
Large Subunit ◽  
Structure And Function ◽  
Sulfhydryl Groups ◽  
Relative Mass ◽  
Nitrobenzoic Acid ◽  
Significant Difference ◽  
Ribulosebisphosphate Carboxylase ◽  
Cold Hardy ◽  
And Function ◽  
Kinetics Of

A comparison of ribulosebisphosphate carboxylase–oxygenase from the leaves of the non-acclimated, cold-hardy species, Solanum commersonii, and the nonacclimated, nonhardy species, Solanum tuberosum showed that this enzyme from the two species differed in structure and function. The results of sulfhydryl group titration with 5,5′-dithiobis(2-nitrobenzoic acid) indicated that the kinetics of titration and the number of accessible sulfhydryl groups in the native enzymes were different. After 30 min, the enzyme from the hardy species had 1.7 times fewer sulfhydryl groups titrated than that from the nonhardy species. In the presence of 1% (w/v) sodium dodecyl sulfate, the total number of sulfhydryl groups titratable with 5,5′-dithiobis-(2-nitrobenzoic acid) was the same for both species. However, this denaturant had a differential effect on the kinetics of titration with 5,5′-dithiobis(2-nitrobenzoic acid). Both enzymes had a native molecular weight of about 550 000. The quaternary structures of the two enzymes were similar with the presence of large and small subunits of 54 000 and 14 000, respectively. However, there was more polypeptide of 108 000 – 110 000 present in preparations of the enzyme from S. tuberosum than from S. commersonii. This polypeptide is an apparent dimer of the large subunit on a relative mass basis. The large subunit of the enzyme from S. tuberosum was more sensitive to the absence of reducing agent and was more sensitive to freezing and thawing than the large subunit of the enzyme from S. commersonii. Catalytic properties of both enzymes at 5 and 25 °C indicated no significant difference in the [Formula: see text] at either temperature. However, the Vmax at 5 °C for the enzyme from S. commersonii was 35% higher than that of the enzyme from S. tuberosum. In contrast, the Vmax at 25 °C for the enzyme of the hardy species was 250% lower than that of the enzyme from the nonhardy species.

Effect of the concentration of 5,5'-dithiobis(2-nitrobenzoic acid) on parameters of the kinetics of its chemisorption on thiol derivatives of cellulose

1986 ◽  
Vol 51 (3) ◽  
pp. 545-552 ◽  
Author(s):  
Albert Breier ◽  
Peter Gemeiner ◽  
Milan J. Beneš
Keyword(s):  
Ethyl Cellulose ◽  
Chemical Structure ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Cellulose Derivatives ◽  
Experimental Conditions ◽  
Nitrobenzoic Acid ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sorbate Concentration

Equations describing the dependence of parameters of sorption kinetics on the sorbate concentration have been determined. The validity of the equations has been verified for the chemisorption of 5,5'-dithiobis(2-nitrobenzoic acid) on bead O-(2-mercaptoethyl)-, O-(3-mercapto-2-hydroxy-propyl)- and O-[2-(4-mercaptophenylsulfonyl)ethyl]cellulose. Isothermic constants obtained from the equations can be calculated also under experimental conditions unfavourable for their determination. These constants may be utilized for characterizing relations between the chemical structure of cellulose derivatives and the sorption process. The equation which provides a complete time-concentration description of sorption is suggested.

scholarly journals Comparison of chloramphenicol acetyltransferase variants in staphylococci. Purification, inhibitor studies and N-terminal sequences

1979 ◽  
Vol 177 (2) ◽  
pp. 575-582 ◽  
Author(s):  
J E Fitton ◽  
W V Shaw
Keyword(s):  
Chloramphenicol Acetyltransferase ◽  
Histidine Residue ◽  
Electrophoretic Variants ◽  
Nitrobenzoic Acid ◽  
Mechanism Of Catalysis ◽  
Michaelis Constants ◽  
Type C ◽  
High Degree ◽  
Kinetics Of ◽  
Similar Amino Acid

Four electrophoretic variants of chloramphenicol acetyltransferase (types A, B, C and D) found in chloramphenicol-resistant staphylococci were purified by affinity chromatography. Michaelis constants and the kinetics of inactivation with a variety of reagents for the four variants are virtually identical. Their similar amino acid compositions and near identical N-terminal sequences suggest a high degree of overall sequence homology. The thiol-specific reagents 5,5′-dithiobis-(2-nitrobenzoic acid), 2-nitro-5-thiocyanobenzoic acid and 2,2′-dithiopyridine are without significant effect on enzyme activity, whereas 1-fluoro-2,4-dinitrobenzene, N-ethylmaleimide, p-chloromercuribenzoic acid, iodoacetamide, and, particularly, bromoacetyl-CoA and diethyl pyrocarbonate are potent inhibitors. Iodoacetate is not an inhibitor. The results of chemical modification studies on the four enzyme variants and the identification of 3-carboxymethylhistidine in acid hydrolysates of one variant (type C) after inactivation with iodoacetamide suggest that a unique histidine residue may be involved in the mechanism of catalysis.

scholarly journals Reactions of d-glyceraldehyde 3-phosphate dehydrogenase with chromophoric thiol reagents

1971 ◽  
Vol 124 (3) ◽  
pp. 573-580 ◽  
Author(s):  
P. J. Harrigan ◽  
D. R. Trentham
Keyword(s):  
Dissociation Constant ◽  
Nitrobenzoic Acid ◽  
Significant Rate ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the reaction of d-glyceraldehyde 3-phosphate dehydrogenase with 5,5′-dithiobis-(2-nitrobenzoic acid) show that NAD% dissociates from the enzyme before the reaction. In contrast 2-chloromercuri-4-nitrophenol reacts with the holoenzyme without prior dissociation of NAD%. These studies and observations on the dissociation constant of NAD% to the lobster enzyme show that NAD% must dissociate from sites modified by substrates during the reductive dephosphorylation of 1,3-diphosphoglycerate. All four sites per tetramer of the apoenzyme are acylated by 1,3-diphosphoglycerate. Hydrolysis of the acyl-enzyme occurs at a significant rate even in the absence of NAD%, which may explain previous estimates that only two sites per tetramer can readily be acylated.

Formation and Repair of Papain Sulfenic Acid

1975 ◽  
Vol 53 (3) ◽  
pp. 298-307 ◽  
Author(s):  
W. S. Lin ◽  
D. A. Armstrong ◽  
G. M. Gaucher
Keyword(s):  
Disulfide Bonds ◽  
Sodium Arsenite ◽  
Sulfenic Acid ◽  
Γ Irradiation ◽  
Molar Ratios ◽  
Nitrobenzoic Acid ◽  
High Concentrations ◽  
Activity Loss ◽  
Sulfenic Acids ◽  
Kinetics Of

The inactivation of highly purified papain (2 × 10−5 M in distilled water) by hydrogen peroxide, generated by the γ-irradiation of water, was examined. The kinetics of activity loss at 23 °C was second order (k = 3.7 × 103 M−1 min−1) for papain:peroxide molar ratios of 1:1 or 2:1. Loss of activity is accompanied by a parallel loss of sulfhydryl; however, the sulfhydryl losses, as determined with 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB) or p-hydroxymercuribenzoate (pHMB), are anomalously either too large or too small, respectively. These discrepancies resulted from the reaction of inactive papain with either the thiol anion product of the DTNB reaction, or with the pHMB reagent itself. The addition of 1.2 M urea to the DTNB reaction mixture significantly decreased this error. Inactive papain reacted with high concentrations of cysteine or cyanide to yield completely repaired active papain, and with benzylamine to yield non-repairable, inactive papain. Sodium arsenite, which is capable of reducing sulfenic acids but not disulfide bonds, readily repaired peroxide-inactivated papain. A completely inactive but repairable papain fraction was isolated by virtue of its lessened ability to bind to a tetrapeptide inhibitor immobilized on Sepharose. The cumulative results indicate that the peroxide inactivation of papain is due almost exclusively to the formation of papain sulfenic acid (Cys25—SOH).

scholarly journals Kinetics of inactivation of glutamate decarboxylase by cysteine-specific reagents.

2001 ◽  
Vol 48 (2) ◽  
pp. 573-578 ◽  
Author(s):  
S J McCormick ◽  
G Tunnicliff
Keyword(s):  
Escherichia Coli ◽  
Enzyme Activity ◽  
Mercuric Chloride ◽  
Rate Constants ◽  
Binding Sites ◽  
Glutamate Decarboxylase ◽  
Thiol Group ◽  
E Coli ◽  
Nitrobenzoic Acid ◽  
Kinetics Of

Mercuric chloride, p-chloromercuribenzoate and 5,5'-dithiobis(2-nitrobenzoic acid) irreversibly inhibited the activity of Escherichia coli glutamate decarboxylase. Their second order rate constants for inactivation are 0.463 microM(-1) min(-1), 0.034 microM(-1) min(-1), 0.018 microM(-1) min(-1), respectively. The characteristics of the inhibition by the three thiol-group reagents supports the idea that cysteinyl residues at the binding sites for the cofactor and/or the substrate are important for enzyme activity in E. coli.

scholarly journals Kinetic studies on protoporphyrinogen oxidase inhibition by diphenyl ether herbicides

1991 ◽  
Vol 277 (1) ◽  
pp. 17-21 ◽  
Author(s):  
J M Camadro ◽  
M Matringe ◽  
R Scalla ◽  
P Labbe
Keyword(s):  
Methyl Ester ◽  
Diphenyl Ether ◽  
Kinetic Studies ◽  
Inhibition Kinetics ◽  
Mitochondrial Membranes ◽  
Protoporphyrinogen Oxidase ◽  
Nitrobenzoic Acid ◽  
Diphenyl Ethers ◽  
Oxidase Inhibition ◽  
Kinetics Of

Diphenyl ethers (DPEs) and related herbicides are powerful inhibitors of protoporphyrinogen oxidase, an enzyme involved in the biosynthesis of haems and chlorophylls. The inhibition kinetics of protoporphyrinogen oxidase of various origins by four DPEs, (methyl)-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (acifluorfen and its methyl ester, acifluorfen-methyl), methyl-5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-chlorobenzoate (LS 820340) and methyl-5-[2-chloro-5-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid (RH 5348), were studied. The inhibitions of the enzymes from maize (Zea mays) mitochondrial and etiochloroplastic membranes and mouse liver mitochondrial membranes were competitive with respect to the substrate, protoporphyrinogen IX, for all four molecules. The relative efficiencies of the inhibitors were: acifluorfen-methyl greater than LS 820340 much greater than RH 5348 greater than or equal to acifluorfen. The four molecules showed mixed-competitive type inhibition of the enzyme from yeast mitochondria where acifluorfen, a carboxylic acid, had the same inhibitory activity as its methyl ester, acifluorfen-methyl, and both were much greater than that of LS 820340 and RH 5348.

Sign in / Sign up

Export Citation Format

Share Document