Biosynthesis of uridine diphosphate N-acetyl-D-mannosaminuronic acid from uridine diphosphate N-acetyl-D-glucosamine in Escherichia coli: Separation of enzymes responsible for epimerization and dehydrogenation

The biosynthesis of uridine diphosphate N-acetyl-D-mannosaminuronic acid from uridine diphosphate N-acetyl-D-glucosamine occurs in two steps. The enzyme responsible for the first step, the epimerization of uridine diphosphate N-acetyl-D-glucosamine to uridine diphosphate N-acetyl-D-mannosamine, is separated by means of hydroxylapatite chromatography from the enzyme for the second step, the NAD-linked dehydrogenation of uridine diphosphate N-acetyl-D-mannosamine. At equilibrium of the epimerase reaction, the ratio of the glucosamine residue to the mannosamine residue is about 9:1.