2 OMEGA-AMINO ACID TRANSAMINASES FROM BACILLUS-CEREUS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 81  (5) , 1375-1381
Abstract
B. cereus strain K-22 produced 2 distinct .omega.-amino acid transaminases, 1 catalyzing the transamination between .beta.-alanine and pyruvic acid and the other that between GABA and .alpha.-ketoglutaric acid. The 2 enzymes were partially purified and separated from each other by various chromatographies. .beta.-Alanine: pyruvic acid transaminase and GABA: .alpha.-ketoglutaric acid transaminase were induced by the addition of .beta.-alanine and GABA, respectively, to the growth medium. .beta.-Alanine transaminase showed an optimum pH of 10.0 and optimum temperature of 35.degree. C, and its Km values for .beta.-alanine and pyruvic acid were both 1.1 mM. GABA acid, .epsilon.-aminocaproic acid, 2-aminoethylphosphonic acid and propylamine showed about 30-40% of the activity of .beta.-alanine as amino donors, and oxalacetic acid was as good an amino acceptor as pyruvic acid. The optimum pH and temperature of GABA transaminase were 9.0 and 50.degree. C, respectively, and its Km value for GABA was 2.8 mM, while that for .alpha.-ketoglutaric acid was 2.3 mM. GABA and .delta.-aminovaleric acid were good amino donors but other .omega.-amino acids were virtually inactive with GABA transaminase; .alpha.-ketoglutaric acid, and to a lesser extent glyoxylic acid, were active amino acceptors. SH reagents specifically activated GABA transaminase.