ω-Amino acid: pyruvate aminotransferase, purified to homogeneity and crystallized from a Pseudomonas sp. F-126, has a molecular weight of 172, 000 or 167, 000±3000 as determined by the gel-filtration or sedimentation equilibrium method, respectively. The enzyme catalyzes the transamination between various ω-amino acids or amines and pyruvate which is the exclusive amino acceptor. α-Amino acids except L-α-alanine are inert as amino donor. The Michaelis constants are 3.3mM for β-alanine, 19mM for 2-aminoethane sulfonate and 3.3mM for pyruvate. The enzyme has a maximum activity in the pH range of 8.5_??_10.5. The enzyme is stable at pH 8.0_??_10.0 and at up to 65°C at pH 8.0. Carbonyl reagents strongly inhibit the enzyme activity. Pyridoxal 5'-phosphate and pyridoxamine 5'-phosphate reactivate the enzyme inactivated by carbonyl reagents. The inhibition constants were determined to be 0.73mM for D-penicillamine and 0.58mM for D-cycloserine. Thiol reagents, chelating agents and L-α-amino acids showed no effect on the enzyme activity.
Japan Society for Bioscience, Biotechnology, and Agrochemistry