UDP-glucose 4-epimerase from saccharomyces fragilis. Presence of an essential arginine residue at the substrate-binding site of the enzyme

Mukherji, S. ; Bhaduri, A. (1986) UDP-glucose 4-epimerase from saccharomyces fragilis. Presence of an essential arginine residue at the substrate-binding site of the enzyme Journal of Biological Chemistry, 261 (10). pp. 4519-4524. ISSN 0021-9258

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Official URL: http://www.jbc.org/content/261/10/4519.abstract

Abstract

UDP-glucose 4-epimerase from Saccharomyces fragilis was inactivated by the arginine-specific reagents phenylglyoxal, 1,2-cyclohexanedione, and 2,3-butanedione following pseudo first order reaction kinetics. The reaction order with respect to phenylglyoxal was 1.8 and that with respect to the other two diones was close to unity. Protection afforded by substrate and competitive inhibitors against inactivation by phenylglyoxal and the reduced interaction of 1-anilinonaphthalene 8-sulfonic acid, a fluorescent probe for the substrate-binding region after phenylglyoxal modification, suggested the presence of an essential arginine residue at the substrate-binding region. Experiments with [7-14C]phenylglyoxal in the presence of UMP, a ligand known to interact at the substrate-binding region, showed that only the arginine residue at the active site could be modified by phenylglyoxal. The characteristic coenzyme fluorescence of the yeast enzyme was found to be enhanced three times in phenylglyoxal-inactivated enzyme suggesting the incorporation of the phenyl ring near the pyridine moiety of NAD.

Item Type:Article
Source:Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
ID Code:26452
Deposited On:06 Dec 2010 12:30
Last Modified:17 May 2016 09:44

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