Studies on the mechanism of action of 6-uracil methyl sulfone in mouse Ehrlich ascites tumor cells in vitro.

Orotic acid is utilized by many mammalian and bacterial systems for the biosynthesis of the pyrimidines found in ribonucleic (UNA) and deoxyribonucleic (DNA) acids. 6-Uracil methyl sulfone (UMS) is one of several orotic acid analogs which have been synthesized and studied by Greenbaum, Hohnes, and Welch (1, 2, 15). Hohnes and Welch have shown (4) that UMS noncompetitively inhibits the growth of several strains of LactchacÃ1⁄4lusbulgaricus in media supplemented with orotic acid, L-dihydroorotate or carbamyl-DLaspartate. Although this inhibition could not be reversed by uridine-5'-phosphate, a crude prepara