Desulfuration of l-cysteine through transamination and transsulfuration in rat liver.
Desulfuration of L-cysteine by rat liver via a pathway of transamination followed by transsulfuration was studied using cyanide as a sulfur acceptor. More than a 5-fold increase in formation of thiocyanate from L-cysteine and cyanide was observed in the presence of 2-oxoglutarate and pyruvate. L-Cysteine aminotransferase and 3-mercaptopyruvate sulfurtransferase activities in the same preparations were also determined. It was concluded that L-cysteine was desulfurated through transamination and transsulfuration of the resulting 3-mercaptopyruvate, and that the rate-limiting step appears to be the transamination reaction.
D000818:Animals; D003545:Cysteine / Q000378:metabolism*; D007656:Ketoglutaric Acids; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D011773:Pyruvates; D051381:Rats; D013438:Sulfhydryl Compounds; D013466:Sulfurtransferases / Q000378:metabolism*; D013861:Thiocyanates / Q000096:biosynthesis; D000637:Transaminases / Q000378:metabolism*
D007656:Ketoglutaric Acids; D011773:Pyruvates; D013438:Sulfhydryl Compounds; D013861:Thiocyanates; D000637:Transaminases; C019968:cysteine aminotransferase; D013466:Sulfurtransferases; D003545:Cysteine