A Novel Acidic Myotoxic Phospholipase A2 of Colombian B. asper Venom. Isolation and Functional Characterization

Myotoxic phospholipases A2 are responsible for many clinical signs in envenomation by Bothrops snakes. A new myotoxic acidic PLA2 Asp 49 was isolated from Colombian Bothrops asper venom. It was isolated by high efficiency liquid chromatography and named BaCol PLA2. It had a molecular weight of 14180.69 Da and an isoelectric point of 4.4. The complete sequence obtained by cDNA cloning, with access number in the gene bank MF319968; this sequence evidenced a mature product of 124 amino acids with Asp in 49 position. In vivo assays in mice demonstrated profuse oedema and myotoxicity evidenced by increase of creatina kinasa in plasma and severe and diffuse damage to the muscular fibers, further vacuolization and hyalinization necrosis of the sarcoplasm showed by histopathology with hematoxylin and eosin staining of gastrocnemius muscle. In vitro studies showed cell membrane damage without phosphatidylserine exposure, an early apoptosis hallmark. Further BaCol PLA2 evidenced high indirect hemolytic activity and moderate anticoagulant action. The toxin showed homology with others acidic PLA2 isolated from Bothrops venoms, including one isolated from B. asper of Costa Rica. Unlike this, BaCol PLA2 was myotoxic.