Cysteic acid transaminase

S. Darling. Cysteic acid transaminase. Nature, 1952, 170 749. F. Chatagner, B. Bergeret, T. Sejourne, and C. Fromageot. Transamination et desulfination de l ac. cysteinesulfinique. Bio-chim. Biophys. Acta, 1952, 9 340. 

The pathway of Haines (1973b) also differs from that of Davies et al. (1966) in that cysteic acid is an intermediate rather than on a side pathway. He proposes the conversion of cysteic acid to sulfopyruvate by a transaminase. Recently it has been shown that aspartate transaminase will catalyze this step at high rates and, furthermore, that sulfopyruvate can be further metabolized to 3-sulfolactate by purified malate dehydrogenase (Harwood and Nicholls, 1979). 

A mixture of cysteic acid with oxaloacetic or o-ketoglutaric acid was maintained for one hour at pH of 7.7 in a 0.07 M phosphate buffer solution with transaminase, prepared according to Cohen s technic. Under these conditions transamination amounts to 15 to 18%. To the mixture so obtsuned and consequently containing a certain amount of sulfopyruvic acid, they added either ground liver or ground muscle and then maintained the reaction mixture for two hours in presence of oxygen. In each of these experiments the authors were unable to show any appreciable formation of sulfate from sulfopyruvic acid. 

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