Purification and properties of L-ornithine delta-aminotransferase from gramicidin S-producing Bacillus brevis.
In gramicidin S-producing Bacillus brevis, the addition of L-ornithine to the minimal medium with L-glutamate as the sole carbon and nitrogen source caused an 8-fold induction of L-ornithine delta-aminotransferase [EC 2.6.1.13]. The enzyme was purified to homogeneity. The native enzyme had a molecular weight of about 88,000 after gel filtration and consisted of two subunits with an identical in molecular weight of about 45,000. The enzyme was specific for L-ornithine (Km = 1.05 mM) as an amino donor and for 2-oxoglutarate (Km = 6.25 mM) as an amino acceptor, and catalyzed the conversion of L-ornithine and 2-oxoglutarate, respectively, to glutamic-gamma-semialdehyde, which is spontaneously cyclized to delta 1-pyrroline-5-carboxylate and L-glutamate. The enzyme exhibits an absorption maximum at 425 nm at neutral pH, and 1 mol of pyridoxal phosphate is bound per subunit. The enzyme activity was irreversibly inhibited by gabaculine, and L-ornithine protected the enzyme from the inhibition. The N-terminal amino acid sequence revealed a noteworthy similarity between human and yeast L-ornithine delta-aminotransferases in residues 17-28 of the B. brevis enzyme.
Takechi
M
M
Department of Biochemistry, Hyogo College of Medicine.
Kanda
M
M
Hori
K
K
Kurotsu
T
T
Saito
Y
Y
D000595:Amino Acid Sequence; D001120:Arginine / Q000494:pharmacology; D001407:Bacillus / Q000201:enzymology* / Q000378:metabolism; D003509:Cyclohexanecarboxylic Acids / Q000494:pharmacology; D006096:Gramicidin / Q000096:biosynthesis; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D009952:Ornithine / Q000494:pharmacology; D009953:Ornithine-Oxo-Acid Transaminase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification*; D011732:Pyridoxal Phosphate / Q000032:analysis; D013379:Substrate Specificity
D003509:Cyclohexanecarboxylic Acids; D006096:Gramicidin; C012987:gabaculine; D011732:Pyridoxal Phosphate; D001120:Arginine; D009952:Ornithine; D009953:Ornithine-Oxo-Acid Transaminase