CHARACTERIZATION AND CYTOTOXICITY OF L-AMINO-ACID OXIDASE FROM THE VENOM OF KING COBRA (OPHIOPHAGUS HANNAH)

The aim of this project was to determine the cytotoxic components from the venom of king cobra, Ophiophagus hannah. Venom was purified by a combination of gel-filtration, ion-exchange and reversed-phase chromat ographic steps. The biochemical properties of the cytotoxic component were consistent with those of L-amino acid oxidase, The molecular,weig ht of the enzyme was estimated to be 150 000 by gel filtration and 70 000 under the denaturing conditions of SDS-PAGE, indicating a dimer, I t has an isoelectric point of 4.5 and is a glycoprotein. The N-termina l sequence of L-amino acid oxidase from the king cobra venom was deter mined to be SVINLEESFQEPEYE. The cytotoxicity of L-amino acid oxidase was observed in stomach cancer, murine melanoma, fibrosarcoma, colorec tal cancer and Chinese hamster ovary cell lines, Cytotoxicity resulted in the loss of ability in attachment and inhibition of cell prolifera tion, The cytotoxic protein decreased the level of cell proliferation by 74% according to [H-3]thymidine uptake assay. The mechanism of enzy me action mag be related to the inhibition of thymidine incorporation and an interaction with DNA. (C) 1997 Elsevier Science Ltd.