Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alterations in hepatic metabolism of S-amino acids were monitored over one week in male rats treated with a single dose of ethanol (3 g/kg, ip). Methionine and S-adenosylhomocysteine concentrations were increased rapidly, but S-adenosylmethionine, cysteine, and glutathione (GSH) decreased following ethanol administration. Activities of methionine adenosyltransferase, cystathionine gamma-lyase and cystathionine beta-synthase were all inhibited. gamma-Glutamylcysteine synthetase activity was increased from t = 8 hr, but GSH level did not return to control for 24 hr. Hepatic hypotaurine and taurine levels were elevated immediately, but reduced below control in 18 hr. Changes in serum and urinary taurine levels were consistent with results observed in liver. Cysteine dioxygenase activity was increased rapidly, but declined from t = 24 hr. The results show that a single dose of ethanol induces profound changes in hepatic S-amino acid metabolism, some of which persist for several days. Ethanol not only inhibits the cysteine synthesis but suppresses the cysteine availability further by enhancing its irreversible catabolism to taurine, which would play a significant role in the depletion of hepatic GSH.
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PMID:Alterations in hepatic metabolism of sulfur-containing amino acids induced by ethanol in rats. 1262 41

Alterations in the hepatic metabolism of S-amino acids were examined in male rats injected with a single dose of ethanol (3 g/kg, i.p.). The hepatic concentrations of methionine and S-adenosylhomocysteine (SAH) were increased, but S-adenosylmethionine (SAM), cysteine, and glutathione (GSH) decreased rapidly following ethanol administration. The activities of methionine adenosyltransferase (MAT), cystathionine beta-synthase (CbetaS) and cystathionine gamma-lyase (CgammaL) were all inhibited. Gamma-glutamylcysteine synthetase (GCS) activity was increased from t = 8 hr, but hepatic glutathione (GSH) level did not return to control for 48 hr. Both hepatic hypotaurine and taurine levels were increased immediately, which were reduced to below control from t = 18 hr. Changes in the serum concentration of taurine were consistent with results observed in the liver. Cysteine dioxygenase (CDO) activity was increased rapidly, but declined from t = 24 hr. The results indicate that an acute dose of ethanol induces significant alterations in the metabolism of S-amino acids in the liver. Ethanol depresses the cysteine availability for GSH synthesis not only by inhibiting the transsulfuration reactions but also by enhancing its irreversible catabolism to taurine via hypotaurine. The physiological significance of this finding is discussed.
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PMID:Effect of acute ethanol administration on S-amino acid metabolism: increased utilization of cysteine for synthesis of taurine rather than glutathione. 1290 7