Purification and characterization of L-amino acid oxidase from the venom of Trimeresurus mucrosquamatus (Taiwan habu snake)

Abstract

Purification and characterization of L-amino acid oxidase from the venom of Trimeresurus mucrosquamatus (Taiwan habu snake). Toxicon 26, 695 – 706, 1988. — L-Amino acid oxidase (EC. 1.4.3.2) was purified to homogeneity via four steps consisting of Sephadex G-100, CM-Toyopearl 650M, and first and second granulated hydroxyapatite column chromatographies. The mol. wt of the enzyme was 140,000 when estimated by analytical gel filtration and was 70,000 by sodium dodecyl sulfate - polyacrylamide gel electrophoresis, suggesting that the enzyme is composed of two identical subunits. The enzyme has an absorption spectrum characteristic of flavoprotein, contains 2 moles of FMN per mole of enzyme and has an isoelectric point of 5.4. The enzyme oxidatively deaminated hydrophobic amino acids such as Leu, Met, Phe, and Tyr while basic amino acids except for Lys were also oxidized though at slower rates. This specificity was generally similar, with some exceptions, to that of the enzyme from Trimeresurus flavoviridis venom. For oxidative deamination of Leu, K m and maximum velocity of the enzyme were 1.17 mM and 9.9 units/mg, respectively, at pH 7.6. The activity was inhibited almost completely by heavy metal ions, some aromatic benzoates and sulfhydryl reagents but not by metal-chelating agents.