Properties of an Aminotransferase of Pea (Pisum sativum L.).

A transaminase (aminotransferase, EC 2.6.1) fraction was partially purified from shoot tips of pea (Pisum sativum L. cv. Alaska) seedlings. With alpha-ketoglutarate as co-substrate, the enzyme transaminated the following aromatic amino acids: d,l-tryptophan, d,l-tyrosine, and d,l-phenylalanine, as well as the following aliphatic amino acids: d,l-alanine, d,l-methionine, and d,l-leucine. Of other alpha-keto acids tested, pyruvate and oxalacetate were more active than alpha-ketoglutarate with d,l-tryptophan. Stoichiometric yields of indolepyruvate and glutamate were obtained with d,l-tryptophan and alpha-ketoglutarate as co-substrates. The specific activity was three times higher with d-tryptophan than with l-tryptophan.