Isolation and characterization of a myotoxic phospholipase A(2) from the venom of the arboreal snake Bothriechis (Bothrops) schlegelii from Costa Rica

摘要

A new myotoxic phospholipase Aa was isolated from the venom of the arboreal snake Bothriechis schlegelii (formerly Bothrops schlegelii) from Costa Rica, by ion-exchange chromatography on CM-Sephadex. B. schlegelii myotoxin I is a basic protein (pI > 9.3) with a subunit molecular weight of 15 kDa, which migrates as a dimer in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. This myotoxin is recognized by antibodies generated against Bothrops asper myotoxin II (a lysine-49 phospholipase A(2)), by both enzyme-immunoassay and gel immunodiffusion, in the latter case with a pattern of partial identity, The toxin induces rapid myonecrosis upon intramuscular injection in mice, as evidenced by the early increase in plasma creatine kinase activity and by direct intravital microscopic observation. B. schlegelii myotoxin I also induces edema in the mouse footpad assay and exerts lethal activity (LD(50) similar to 2.5 mu g/ g) upon intravenous injection. The toxin has a low phospholipase A(2) activity (4.2 mu Eq . mg(-1). min(-1)) using egg yolk phospholipids as substrate. It also shows a weak anticoagulant effect in vitro. Its N-terminal sequence, SMYELGKMILLETGKNAATSYIAYG, shows 93% homology with both Bothrops asper myotoxin II and B. jararacussu bothropstoxin I, suggesting that B. schlegelii myotoxin I may be a new lysine-49 variant of this family of myotoxic phospholipases A(2). (C) 1997 Academic Press.