Partial Purification and Properties of a beta-d-Glucosyltransferase Occurring in Germinating Phaseolus aureus Seeds.
A soluble enzyme that transfers d-glucose from uridine diphosphate d-glucose to low molecular weight hydroxyl compounds has been discovered in germinating mung bean (Phaseolus aureus) seeds and purified 220-fold. Phenol and n-butyl alcohol are the most reactive aceptors examined. The reactivities of various acceptors are largely independant of hydroxyl group acidities or of the electronic properties of the acceptors. The space-filling properties or length of the acceptors, on the other hand, appear to be the predominant controlling factor which determines their relative abilities to accept d-glucose, the ideal size being that of phenol and n-butyl alcohol. The enzyme is deactivated by p-chloromercuribenzene sulfonate; dithiothreitol imparts considerable stabilization to the enzyme. It does not require exogenously added metal ions but is slightly stimulated by magnesium ion. On the other hand, the enzyme is partially inhibited by 10 mm manganous ion, cobalt ion, ferrous ion, and ethylenediaminetetraacetate. Zinc ion at 10 mm concentrations strongly inhibits the enzyme. The molecular weight of the enzyme, determined by gel filtration, is approximately 62,000.
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Department of Biochemistry, University of California, Berkeley, California 94720.
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