Metabolism of cysteine in Ehrlich ascites tumour, mouse skeletal muscles and liver.
The cell membrane of intact Ehrlich ascites tumour (EAT) cells limits the penetration and thus the utilization of exogenous cysteine in vitro. In homogenates the uptake of cysteine is the greatest in skeletal muscle, smaller in EAT and the smallest in liver. 2-Oxoglutarate, initiating the pyruvate pathway of cysteine catabolism, raises cysteine utilization only in liver homogenates. Although it also raises taurine formation, it shifts the equilibrium from the oxidative toward the anaerobic pyruvate pathway of cysteine metabolism. 2-Oxoglutarate has no effect on cysteine metabolism in EAT and only a small effect on this process in muscle homogenates. Limitation of cysteine metabolism in the pyruvate pathway in tumour cells is not compensated by increased cysteine oxidation. The greatest increase in protein thiol groups was observed in EAT homogenates; it was markedly reduced in the presence of 2-oxoglutarate.
D000693:Anaerobiosis; D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D013431:Sulfates / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013654:Taurine / Q000378:metabolism
D007656:Ketoglutaric Acids; D011506:Proteins; D011773:Pyruvates; D013431:Sulfates; D013438:Sulfhydryl Compounds; D013654:Taurine; D019289:Pyruvic Acid; D003545:Cysteine