AJP - Endocrinology and Metabolism, Vol 264, Issue 5 E782-E789, Copyright © 1993 by American Physiological Society
Catabolism of cysteine, cystine, cysteinesulfinate, and OTC by isolated perfused rat hindquarter
J. L. Ensunsa, L. L. Hirschberger and M. H. Stipanuk
Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853.
The metabolism of cysteine and related compounds was investigated in the
isolated perfused hindquarter of the rat. An erythrocyte-based perfusion
medium was used; use of a perfluorochemical emulsion, FC-43, resulted in
apparent chemical oxidation of cysteine, whereas bovine erythrocytes did
not appear to contribute significantly to the metabolism of cysteine. Rat
skeletal muscle perfused with L-[35S]cysteine, L-[35S]cystine,
L-[35S]cysteinesulfinate, or L-2-oxo-[35S]thiazolidine-4-carboxylate (OTC)
for 2 h produced [35S]sulfate and [35S]taurine. In all cases, the
partitioning of cysteine or cysteinesulfinate between metabolism to taurine
and sulfate was similar, suggesting that cysteine metabolism in hindquarter
may occur via formation and catabolism of cysteinesulfinate by either
cysteinesulfinate decarboxylase or aspartate (cysteine-sulfinate)
aminotransferase. However, the activity of cysteine dioxygenase was
extremely low, suggesting that the conversion of cysteine to
cysteinesulfinate may have been non-enzymatic.
