Leucine catabolism in human term placenta.

It has been shown that L-leucine is transaminated in the presence of 2-oxoglutarate and subsequently decarboxylated by human term placenta. About 60% of the transaminase activity was recovered in the cytoplasmic fraction and the remaining amount in the mitochondria. The dehydrogenase activity is localized almost exclusively in the mitochondrial fraction. The rate of the transamination of L-leucine is many times higher than the rate of decarboxylation of oxoacid. The possible physiological role of leucine degradation in human placenta is discussed.