Abstract

RUIZ, Nora et al. Some kinetic properties of a L-amino acid oxidase isolated from Bothrops atrox peruvian snake venom "Jergón". Rev. Soc. Quím. Perú [online]. 2010, vol.76, n.3, pp.218-226. ISSN 1810-634X.

We have determined main kinetic properties of a L-amino acid oxidase (L-AO) purified from Bothrops atrox venom, on different aminoacids as L-leucine, L-phenylalanine, L-methionine and L-arginine. Previously optima pH curves were establish for each aminoacid and then K_m, V_max, K_cat y K_cat/K_m values at pH 7,5 and 8,5 were calculated. Furthermore Ki values using anthranilic, benzoic, sulphanylic and salycilic acids were obtained. Between substrates assayed at pH 8,5, L-AO showed higher specific activity on L-phenilalanine, followed by L- leucine, L-methionine and L-arginine, being optimum values of 8,1 for L-metionine, 8,9 for L-arginine, and 8,2 for L-fenilalanine. According to catalytic efficiency, L-leucine was the best substrate at pH 7,5 (K_cat/k_m = 40,90 x 10⁴ s^-1 M^-1) and 8,5 (K_cat/k_m = 71,21 x 10⁴ s^-1 M^-1). On the other hand, enzymatic inhibition assays showed that anthranilic acid had the lowest K_i value (0,008 mM), fitting it to a non-competitive model. Benzoic acid was considered a competitive inhibitor, while salicylic and sulphanylic acid showed mixed-type inhibition.

Keywords : L-amino acid oxidase; Bothrops atrox; kinetics parameters; enzyme inhibition; K_i.

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