[Coordination of the main and reutilization pathways of nucleotide biosynthesis in the lymphocytes in leukemia]

Coordination of these two pathways of nucleotide synthesis in leukocytes under chronic lympholeukosis was studied using incorporation of 14C-orotic acid and 14C-uridine into uridine mono-, di- and triphosphates and also into RNA. Simultaneously, activity of the key enzymes, participating in metabolism of orotic acid and of uridine, was measured: OMP-pyrophosphorylase /EC 2.4.2.10, orotidine-5'-phosphate: purophosphate phosphorybosyl transferase/ and uridine kinase /EC 2.7.1.48, ATP: uridine-5'-phosphotransferase/. The reutilizational pathway of pyrimidine nucleotide synthesis was distinctly activated. At the same time there was only a slight increase in the main pathway of their synthesis in lymphocytes in leukemic form of cronic lympholeukosis. Activities of OMP-pyrophosphorylase and uridine kinase were increased by 30%. An impairment in the coordination of the rates of both pathways of pyrimidine nucleotide synthesis was related to inhibition of OMP-pyrophosphorylase caused by and increase in uridine nucleotide pool.