Studies in tissue metabolism

Publisher Website
Google Scholar
Abstract
Extracts from the mouse sarcomas Crocker 180 and Sarcoma 37, mouse carcinoma 63 and rat carcinoma Walker 256, produce lactic acid from glucose and fructose if cozymase, adenylic acid and a trace of hexosediphosphate are added. Extracts of these tumors rapidly glycolyze glycogen and hexosephos-phates; slices of the same tumors do not, because of the non-diffusibility of these substances. Slices of tumor tissue convert hexosediphosphate into triosephosphate. The distribution of triosephosphate in tumor slices and in the surrounding fluid indicates that the triosephosphate is formed outside the cells, presumably by the action of such enzyme as is exposed in cut and injured cells of the slices. Tumor extracts diluted so as to show the zymohexase activity equivalent to the suspended slices do not form lactic acid either from glucose or hexosediphosphate. Tumor extracts produce lactic acid more rapidly from fructose than from glucose; while tumor slices produce lactic acid about 3-4 times as rapidly from glucose as fructose when the sugar concn. is below 0.5%. The optimum glucose concn. for glycolysis in tumor slices is 02%; the opt. fructose concn. is 10%; the difference in glycolysis is evidently due to different rates of diffusion into the cells. The fermentation of dried yeast and the glycolysis of starch and glycogen in muscle extract are inhibited by dl-glyceraldehyde. The inhibition is much greater in dialyzed preparations. The inhibition of glycolysis in muscle extract by glyceraldehyde is accompanied by inhibition of phosphate esterification. The glycolysis of hexosediphosphate and hexosemonophos-phate is not inhibited. The glycolysis of glycogen, glucose and fructose in tumor extracts is inhibited by glyceraldehyde but lactic acid formation from hexose phosphates is not affected. The action of glyceraldehyde is probably due to inhibition of esterification processes.