The activation of glucose dehydrogenase by p-chloromercuribenzoate |
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Authors: | Clark Bublitz Cheryl A. Lawler |
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Affiliation: | (1) Department of Biochemistry, Biophysics and Genetics, University of Colorado Health Sciences Center, 4200 E. Ninth Ave. B-126, 80262 Denver, Colorado, USA;(2) Dept. of Biochemistry, Biophysics and Genetics, University of Colorado Health Science Center, 80262 Denver, Colorado, USA |
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Abstract: | Summary P-Chloromercuribenzoate alters various reactions of rat liver glucose (hexose phosphate) dehydrogenase differently. The reagent has little effect on the glucose: NAD or the glucose: NADP oxidoreductases, doubles the rates of oxidations of galactose-6-phosphate and glucose-6-phosphate by NADP and greatly stimulates the oxidations of glucose-6-phosphate and galactose-6-phosphate by NAD. The reagent appears to react with a sulfhydryl group of the enzyme since activation is reversed and prevented by mercaptoethanol. The direct reaction of the reagent with the enzyme is indicated by its lower thermal stability in the presence of the p-chloromercuribenzoate. The size of the enzyme appears to be the same when determined by sucrose gradient centrifugation in the presence or absence of p-chloromercuribenzoate. In microsomes, the oxidation of NADH or NADPH hampers measurements of glucose dehydrogenase. Since p-chloromercuribenzoate inhibits microsomal oxidation of reduced nicontinamide nucleotides, it is possible to assay for glucose dehydrogenase accurately in the presence of the mercurial in microsomes and microsomal extracts and thus measure the effectiveness of a detergent in extracting the enzyme from microsomes.Abbreviation pcMB p-chloromercuribenzoic acid |
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Keywords: | hepatic microsomes p-chloromercuribenzoate glucose (hexose phosphate) dehydrogenase |
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