Effect of dietary cystine on methionine metabolism in rat liver.
Cystine supplementation of adequate diets resulted in significantly higher hepatic levels of betaine-homocysteine methyltransferase. Other changes occurred but were a function of the basal diet. When the latter contained 0.25% methionine + 0.5% cystine, the additional cystine caused a markedly lower hepatic cystathionine synthase activity and lower levels of both adenosylmethionine and serine. The metabolic effect of these changes may be enhanced methionine retention and diminished transsulfuration.
D000818:Animals; D050940:Betaine-Homocysteine S-Methyltransferase; D003541:Cystathionine beta-Synthase / Q000378:metabolism; D003553:Cystine / Q000494:pharmacology*; D004044:Dietary Proteins / Q000494:pharmacology*; D006710:Homocysteine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012436:S-Adenosylmethionine / Q000378:metabolism; D012694:Serine / Q000378:metabolism
D004044:Dietary Proteins; D006710:Homocysteine; D012694:Serine; D003553:Cystine; D012436:S-Adenosylmethionine; D008715:Methionine; D008780:Methyltransferases; D050940:Betaine-Homocysteine S-Methyltransferase; C494550:Bhmt protein, rat; D003541:Cystathionine beta-Synthase