Nucleoside Diphosphate-sugar 4-Epimerases I. Uridine Diphosphate Glucose 4-Epimerase of Wheat Germ.
نویسندگان
چکیده
Uridine diphosphate (UDP)-glucose 4-epimerase (EC 5.1.3.2) has been purified over 1000-fold from extracts of wheat germ by MnCl(2) treatment, (NH(4))(2)SO(4) fractionation, Sephadex column chromatography, and adsorption onto and elution from calcium phosphate gel. The enzyme has a pH optimum of 9.0. Km values are 0.1 mm for UDP-d-galactose and 0.2 mm for UDP-d-glucose. NAD is required for activity; K(a) = 0.04 mm. NADH is an inhibitor strictly competitive with NAD; K(i) = 2 mum. Wheat germ also contains UDP-l-arabinose 4-epimerase (EC 5.1.3.5) and thymidine diphosphate (TDP)-glucose 4-epimerase which are distinct from UDP-glucose 4-epimerase.
منابع مشابه
Nucleoside diphosphate-sugar 4-epimerases. II. Uridine diphosphate arabinose 4-epimerase of wheat germ.
Uridine diphosphate (UDP)-arabinose 4-epimerase (EC 5.1.3.5) has been purified at least 20-fold from wheat germ by MnCl(2) treatment, (NH(4))(2)SO(4) fractionation, dialysis, and Sephadex and diethylaminoethyl cellulose column chromatography. The enzyme has no action on UDP-d-glucose, UDP-d-glucuronic acid, or TDP-d-glucose. The pH optimum is 8.0. Km values are 1.5 mM for UDP-d-xylose and 0.5 m...
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Abbreviations: aa, amino acid; AGPase, ADP-glc pyrophosphorylase; ara, arabinose; gal, galactose; galA, galacturonic acid; GALT, gal-1-P uridyltransferase; glc, glucose; glcA, glucuronic acid; man, mannose; PPi, pyrophosphate; SuSy, sucrose synthase; UAGPase, UDP-N-acetylglucosamine pyrophosphorylase; UGE, UDP-glc epimerase; UGPase, UDP-glc pyrophosphorylase; USPase, UDP-sugar pyrophosphorylase...
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عنوان ژورنال:
- Plant physiology
دوره 44 4 شماره
صفحات -
تاریخ انتشار 1969