抄録
UDP-galactose 4-epimerase (EC 5.1.3.2) was purified to a homogeneous state from Bifzdobacterium bifzdum grown on a glucose medium. The molecular weight was estimated to be about 90, 000. The purified enzyme was very stable and 60% of its initial activity survived three months of storage at 4°C even at a low protein concentration (0.2mg/ml). The optimum pH was 9.0, and the Km values for UDP-galactose and UDP-glucose were 5.4×10-4M and 1.4×10-4M. UDP was a competitive inhibitor. The enzyme activity was stimulated by various sugar phosphates, but was slightly inhibited by fructose 1, 6-diphosphate (FDP). A high concentration of galactose or glucose, which had no effect by itself, inhibited the activity in combination with UMP. The inhibition by FDP was also enhanced by combi-nation with UMP.
