Assay and Some Properties of Kidney Transamidinase.

Abstract

1. An assay of transaminidase activity in mammalian kidneys was developed. 2. The enzyme was inhibited by p-chloromercuribenzoic acid. The inhibition could be reversed with reduced glutathione, cysteine, or dimercaprol. These results suggest that transaminidase is a sulfhy-dryl enzyme. 3. Kidneys from a mercury-poisoned rat showed reduced transaminidase activity. The activity could not be restored by addition of dimercaprol to the reaction flask. 4. Canavanine was found to be 3 times as effective as arginine as an amidine donor in the transamidinase system. 5. Kidney transaminidase activity in weanling rats fed a protein-free diet for 12 days was 24% of normal. The activity was restored to 80% of normal by feeding the rats a complete diet for 15 days following the feeding of a protein-free diet for 12 days. Thus, kidney transaminidase activity appears to be dependent on exogenous protein sources.