Glycolysis by Sarcoma 180 of mice treated with 6-mercaptopurine. I. The role of various enzymes in lactate production.

Lactate formation from fructose-1,6-diphosphate in homogenates of Sarcoma 180 from mice, given injections intraperitoneally of 6-mercaptopurine, was sharply de creased as compared with that in tumor homogenates of nontreated animals. The activities of aldolase and triosephosphate isomerase, but not of phosphoglyceraldehyde dehydrogenase and phosphoglyceric acid kinase, were significantly lower, and the ATPase activity was markedly higher in the tumor homogenates of the 6-mercaptopurine-treated animals. The phosphate balance in the glycolysates of this group of homogenates was always negative and was not changed by the addition of glucose to the medium. Addition of crystalline aldolase increased the rate of lactate output to the level of that of homogenates of the nontreated group and shifted the phosphate balance to positive values. Addition of crystalline lactic dehydrogenase or of glucose to either group of homogenates did not significantly change their lactate output.