HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Roy-Burman, P. Articles by Visser, D. W. Search for Related Content PubMed Articles by Roy-Burman, P. Articles by Visser, D. W. Social Bookmarking                      What's this?

Uridine Diphosphate Glucose Dehydrogenase

STUDIES WITH 5-HYDROXYURIDINE DIPHOSPHATE GLUCOSE AND 5,6-DIHYDROURIDINE DIPHOSPHATE GLUCOSE

From the ¹ From the Department of Biochemistry, University of Southern California, School of Medicine, Los Angeles, California 90033

5-Hydroxyuridine diphosphate glucose was prepared enzymatically and 5,6-dihydrouridine diphosphate glucose was prepared by the catalytic reduction of UDP-glucose. The effectiveness of these cofactor analogues as substrates for UDP-glucose dehydrogenase was determined. The rate of oxidation of 5-hydroxyuridine diphosphate glucose was one-sixth that of UDP-glucose at pH 8.7 and one-half that of UDP-glucose at pH 7.0. This behavior is related to the relatively low pK_a value of the analogue. Dihydrouridine diphosphate glucose was oxidized at rates which were almost identical with those observed with UDP-glucose at various pH values.

5-Hydroxyuridine diphosphate glucose inhibited UDP-glucose oxidation in a manner suggesting that the analogue interferes with the NAD⁺ binding site of the enzyme. The undissociated form of the analogue was the more effective inhibitor of UDP-glucose oxidation.

The glucose moiety of the three substrates was oxidized to glucuronate at about the same rate as NAD⁺ was reduced throughout the reaction. These results do not agree with the suggestion that glucose remains unchanged until approximately 1 mole of NAD⁺ is reduced.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?