Biochemical characterization of a red cell UMP kinase variant found in the Warao indians of Venezuela

UMPK 3 is a rare variant of the polymorphic enzyme of human red cells, uridine monophosphate kinase. This homozygote phenotype was detected among the Warao Indians of Venezuela. The UMPK 1 and UMPK 3 enzymes were partially purified following the method described by Tend et al. (1976). The biochemical and kinetic parameters of both variants were studied in crude hemolysates and in partially purified enzymes. A comparison was made with the results previously reported by Teng for UMPK 1 and UMPK 2, and it was concluded that UMPK 3 seems to resemble the other two allelic gene products in Km values for UMP, CMP, and ATP but differs from them in electrophoretic mobility, pH optimum, and thermal stability.