title: Substrate specificity of king cobra (Ophiophagus hannah) venom L-amino acid oxidase.
abstract: 1. Substrate specificity of purified king cobra (Ophiophagus hannah) venom L-amino acid oxidase was investigated. 2. The enzyme was highly specific for the L-enantiomer of amino acid. Effective oxidation of L-amino acid by the enzyme requires the presence of a free primary alpha-amino group but the alpha-carboxylate group is not as critical for the catalysis. 3. The enzyme was very active against L-Lys, L-Phe, L-Leu, L-Tyr, L-Tryp, L-Arg, L-Met, L-ornithine, L-norleucine and L-norvaline and moderately active against L-His, L-cystine and L-Ileu. Other L-amino acids were oxidized slowly or not oxidized. 4. The data suggest the presence of a side chain binding site in the enzyme, and that the binding site comprises at least five 'subsites': the hydrophobic subsites a, b and c; and the two 'amino' binding subsites d and e. Subsite b appears to be able to accommodate two methylene/methyl carbons.
authors.affiliation: Department of Biochemistry, University of Malaya, Kuala Lumpar.
authors.forename: N H
authors.initials: NH
authors.lastname: Tan
authors.forename: M N
authors.initials: MN
authors.lastname: Saifuddin
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D004546:Elapid Venoms / Q000032:analysis*; D007700:Kinetics; D050830:L-Amino Acid Oxidase; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D004546:Elapid Venoms; D000594:Amino Acid Oxidoreductases; D050830:L-Amino Acid Oxidase