Galactokinase of Bifidobacterium bifidum.

Abstract

Crystalline galactokinase was obtained in good yield from Bifidobacterium bifidum grown on galactose medium. This preparation moved as a single protein band in analytical disc electrophoresis and sedimented as a single symmetrical peak under ultracentrifugation. The enzyme exhibited similar physicochemical properties to galactokinase purified from glucosegrown cells of B. bifidum. The enzyme has a molecular weight of 47, 000. Only galactose and ATP were effective as substrate. Km values, optimal pH, cation requirement, inhibition by SH-reagent, heat stability and product inhibition were also investigated.