Purification and Properties of L-Ornithine δ-Aminotransferase from Gramicidin S-Producing Bacillus brevis

• Published in: Journal of biochemistry (Tokyo) 1994-11, Vol.116 (5), p.955-959
• Main Authors: Takechi, Makiko, Kanda, Masayuki, Hori, Kazuko, Kurotsu, Toshitsugu, Saito, Yoshitaka
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arginine - pharmacology; Bacillus - enzymology; Bacillus - metabolism; Bacillus brevis; Cyclohexanecarboxylic Acids - pharmacology; Gramicidin - biosynthesis; gramicidin S; Hydrogen-Ion Concentration; Isoelectric Point; L-ornithine δ-aminotransferase; Molecular Sequence Data; Ornithine - pharmacology; Ornithine-Oxo-Acid Transaminase - antagonists & inhibitors; Ornithine-Oxo-Acid Transaminase - chemistry; Ornithine-Oxo-Acid Transaminase - isolation & purification; Pyridoxal Phosphate - analysis; Substrate Specificity
• ISSN: 0021-924X
• DOI: 10.1093/oxfordjournals.jbchem.a124652

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 δ-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-γ-semialdehyde, which is spontaneously cyclized to Δ-pyrro-line-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 δ-aminotransferases in residues 17–28 of the B. brevis enzyme.