ISSN:
1438-2199
Keywords:
Amino acids
;
Cysteine metabolism
;
3-Mercaptopyruvate pathway
;
Cysteine transamination
;
3-Mercaptolactate-cysteine mixed disulfide
;
Sulfate formation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary We have studied the transamination pathway (3-mercaptopyruvate pathway) ofl-cysteine metabolism in rats. Characterization of cysteine aminotransferase (EC 2.6.1.3) from liver indicated that the transamination, the first reaction of this pathway, was catalyzed by aspartate aminotransferase (EC 2.6.1.1). 3-Mercaptopyruvate, the product of the transamination, may be metabolized through two routes. The initial reactions of these routes are reduction and transsulfuration, and the final metabolites are 3-mercaptolactate-cysteine mixed disulfide [S-(2-hydroxy-2-carboxyethylthio)cysteine, HCETC] and inorganic sulfate, respectively. The study using anti-lactate dehydrogenase antiserum proved that the enzyme catalyzing the reduction of 3-mercaptopyruvate was lactate dehydrogenase (EC 1.1.1.27). Formation of HCETC was shown to depend on low 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) activity. Results were discussed in relation to HCETC excretion in normal human subjects and patients with 3-mercaptolactate-cysteine disulfiduria. Incubation of liver mitochondria withl-cysteine, 2-oxoglutarate and glutathione resulted in the formation of sulfate and thiosulfate, indicating that thiosulfate was formed by transsulfuration of 3-mercaptopyruvate and finally metabolized to sulfate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00805999
