Developmental aspects of uridine diphosphate galactose 4-epimerase in rat intestine.

Kinetic and developmental characteristics of rat intestinal UDP-galactose 4-epimerase activity have been examined. The enzyme in the adult rat had a V(max.) value 2-3 times higher than that of the newborn animal, but the K(m) values for the enzyme in the newborn and adult rat were the same (0.17mm). No differences in epimerase activity were found along the length of the jejuno-ileum of adult animals, but higher activity was detected in the lower portion of the villi and crypts. The specific activity of the enzyme in the newborn rat began to rise at about 17 days of age, reaching a peak at 29 days of age, and then became constant at adult values. Total epimerase activity in the newborn rat liver was 2-5 times higher than the total activity in the intestine, and total epimerase activity in the adult intestine was 3-4 times higher than the total activity in the liver. Cortisone injection did not enhance the increase of epimerase normally seen during development, but caused a decrease in activity of this enzyme in the jejunum in rats up to 17 days of age. After 17 days, cortisone treatment had no effect on epimerase activity.