ALTERED ERYTHROCYTE PYRIMIDINE ACTIVITY IN VITAMIN-B12 OR FOLATE-DEFICIENCY

The net activity of orotidylic pyrophosphorylase and decarboxylase, sequential enzymes which catalyse the formation of uridine monophosphate from orotic acid in de novo pyrimidine biosynthesis, has been evaluated in erythrocytes of patients with folate or cobalamin deficiency. In patients with normoblastic haemopoiesis and normal cobalamin and folate status a direct relationship exists between the maturity of the peripheral blood erythrocyte population, as indicated by G6PD activity, and net orotidylic activity. In contrast in cobalamin or folate deficiency this co‐ordinate relationship is not observed and net orotidylic activity is relatively reduced. Fractionation of erythrocytes by centrifugation demonstrates that this inordinately low orotidylic activity consistently occurs in the young erythrocyte population and is reversed by specific replacement therapy. Copyright © 1979, Wiley Blackwell. All rights reserved