The formation of 5-phosphoribosyl-1-pyrophosphate in human leukemic leukocytes

Abstract

PRPP concentrations and rate of the PRPP formation were determined in leukocyte suspension obtained from patients with acute leukemia and normal controls. The PRPP concentrations were less than 0.03 nmoles 3 × 10 7 cells in leukocytes, which were far less than K m value for PRPP in purine nucleotide synthesis reaction. Therefore the availability of PRPP was considered to be an important factor regulating purine nucleotide formation in human leukemic leukocytes. The amounts of PRPP formed in leukocytes obtained from patients with acute leukemia were shown to have a wide variation from 5.2 to 38.0 nmoles 3 × 10 7 cells hour , and majority of the patients examined was shown to have a significantly low rate of PRPP formation. A significant negative correlation was obtained between the PRPP formation and percentage of immature cells. Availability of R-5-P as rate limiting factor of the PRPP formation was discussed.