Antitumoural Effect of an l‐Amino Acid Oxidase Isolated from Bothrops jararaca Snake Venom

: An l‐amino acid oxidase (BjarLAAO‐I) from Bothrops jararaca snake venom was highly purified using a stepwise sequential chromatography on Sephadex G‐75, Benzamidine Sepharose and Phenyl Sepharose. Purified BjarLAAO‐I showed a molecular weight around 60,000 under reducing conditions and about 125,000 in the native form, when analysed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis and gel filtration, respectively. BjarLAAO‐I is a homodimeric acidic glycoprotein, pI ~5.0, and N‐terminal sequence showing close structural homology with other snake venom LAAOs. The purified enzyme catalysed the oxidative deamination of l‐amino acids, the most specific substrate being l‐Phe. Five amino acids, l‐Ser, l‐Pro, l‐Gly, l‐Thr and l‐Cys were not oxidized, clearly indicating a significant specificity. BjarLAAO‐I significantly inhibited Ehrlich ascites tumour growth and induced an influx of polymorphonuclear cells, as well as spontaneous liberation of H2O2 from peritoneal macrophages. Later, BjarLAAO‐I induced mononuclear influx and peritoneal macrophage spreading. Animals treated with BjarLAAO‐I showed higher survival time.