Metabolism of L-cysteine in guinea pig liver.
The metabolism of L-cysteine in guinea pig liver was studied. Guinea pig liver contained 0.45 +/- 0.05 (mean +/- SD) mumol of cysteine, 0.180 +/- 0.080 mumol of 3-mercaptolactate-cysteine disulfide [S-(2-hydroxy-2-carboxyethylthio)cysteine, HCETC], and 8.082 +/- 0.516 mumol of reduced glutathione per g of fresh tissue. The taurine content was 0.912 +/- 0.158 mumol per g of fresh liver. Cysteine dioxygenase (EC 1.13.11.20) activity was several-fold lower than cysteine aminotransferase (EC 2.6.1.3) activity. Lactate dehydrogenase (EC 1.1.1.27) activity was about 10-fold higher than 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) activity. These results indicate that the oxidative metabolism of L-cysteine in the guinea pig liver is not as active as in the rat liver and that L-cysteine, at least in part, is metabolized via the transaminative pathway, in which 3-mercaptopyruvate is partly reduced to 3-mercaptolactate and is utilized to form HCETC.
Hosaki
Y
Y
Nishina
H
H
Ubuka
T
T
D000818:Animals; D003545:Cysteine / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism*; D050558:Cysteine Dioxygenase; D049308:Dioxygenases; D006168:Guinea Pigs; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D010105:Oxygenases / Q000378:metabolism; D013466:Sulfurtransferases / Q000378:metabolism; D000637:Transaminases / Q000378:metabolism
C001705:beta-mercaptolactate cysteine disulfide; D007770:L-Lactate Dehydrogenase; D010105:Oxygenases; D049308:Dioxygenases; D050558:Cysteine Dioxygenase; D000637:Transaminases; C019968:cysteine aminotransferase; D013466:Sulfurtransferases; C021550:3-mercaptopyruvate sulphurtransferase; D003545:Cysteine