The transsulfuration pathway in Tetrahymena pyriformis.
Four enzymes necessary for the metabolism of methionine by the trans-sulfuration pathway, methionine adenosyltransferase (EC 2.5.1.6), adenosylhomocysteinase (EC 3.3.1.1), cystathionine beta-synthase (EC 4.2.1.22) and cystathionine gamma-lyase (EC 4.4.1.1) were identified in Tetrahymean pyriformis. The ability of these cells to transfer 35S from E135S]methionine to form [35S] cysteine was also observed and taken as direct evidence for the functional existence of this pathway in Tetrahymena. An intermediate in the pathway and an active methyl donor, S-adenosylmethionine, was qualitatively identified in Tetrahymena and its concentration was found to be greater in late stationary phase cells than in early stationary phase cells.
D000818:Animals; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000378:metabolism*; D008716:Methionine Adenosyltransferase / Q000378:metabolism; D051381:Rats; D012435:S-Adenosylhomocysteine; D012436:S-Adenosylmethionine / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*; D013696:Temperature; D013769:Tetrahymena pyriformis / Q000254:growth & development / Q000378:metabolism*
D013455:Sulfur; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D008715:Methionine; D008716:Methionine Adenosyltransferase; D006867:Hydrolases; D003541:Cystathionine beta-Synthase; D003542:Cystathionine gamma-Lyase