Transaminase of L-cysteine in rat liver mitochondria.

Transamination of L-cysteine in rat liver was examined. Specific activity of the reaction in mitochondria was found higher than that in cytosol. The mitochondrial reaction was shown to be catalyzed by two different enzymes. The first was active with 2-oxoglutarate and inactivated by heating at 60 degrees C for 10 minutes; the activity was protected from heat inactivation by the presence of 2-oxoglutarate. The second enzyme was active with pyruvate and more stable than the first under heat treatment; 2-oxoglutarate had little protective effect on this second enzyme. The two enzyme activities were separated by heat treatment and ammonium sulfate fractionation.