Kynurenine pyruvate transaminase and its specific inhibitor in rat intestine.

Kynurenine pyruvate transaminase was partially purified and characterized. The enzyme catalysed the conversion of L-knurenine to kynurenic acid. Transamination rates of 3-hydroxy-DL-kynurenine and 5-hydroxy-DL-kynurenine by the enzyme were 1/2.9 and 1/2.6 of kynurenine. The enzyme showed a higher preference for pyruvate than 2-oxoglutarate as aminoacceptor. The pH optimum of the reaction was 8.0 and 8.5. It was shown that the inhibitor of kynurenine pyruvate transaminase was present in the intestine.