Abstract
L-Leucine-pyruvate and L-leucine-a-ketoglutarate(α-KGA) transaminases were separated by DEAE-cellulose column chromatography and partially purified to 200- and 50-fold, respectively, from the cell-free extract of Acetobacter suboxydans (Gluconobacter suboxydans IFO 3172). The optimum pH range of the former was 5.0_??_5.5 and that of the latter was 8.5_??_9.0. L-Leucine, L-citrulline, and L-methionine were the most effective amino donors for the L-leucine-pyruvate transaminase. Basic amino acids as well as aromatic amino acids were able to be amino donors for the transamination with pyruvate. α-KGA was effective as an amino acceptor for this enzyme. The L-leucine-α-KGA transaminase had the typical properties of the branched-chain amino acid transaminase in its substrate specificity.
The reaction products of the transaminations were identified. L-Alanine was formed from pyruvate and L-glutamate from α-KGA. α-Keto acids formed from various amino acids by the L-leucine-pyruvate transaminase were also identified.
