L-amino acid oxidase from Naja naja oxiana venom

A new L-amino acid oxidase (LAAO) was isolated from the Central Asian cobra Naja naja oxiana venom by size exclusion, ion exchange and hydrophobic chromatography. The N-terminal sequence and the internal peptide sequences share high similarity with other snake venom L-amino acid oxidases, especially with those isolated from elapid venoms. The enzyme is stable at low temperatures (-20 degrees C, -70 degrees C) and loses its activity by heating at 70 degrees C. Specific substrates for the isolated protein are L-phenylalanine, L-tryptophan, L-methionine and L-leucine. The enzyme has antibacterial activity inhibiting the growth of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria. N. naja oxiana LAAO dose-dependently inhibited ADP- or collagen-induced platelet aggregation with IC50 of 0.094 mu M and 0.036 mu M, respectively. The antibacterial and anti-aggregating activity was abolished by catalase. (c) 2007 Elsevier Inc. All rights reserved.