A further examination of the active form of Crotalus adamanteus phospholipase A2

The Phospholipase A2 from Crotalus adamanteus venom has been shown to be active as the dimer or 30 000 molecular weight species, at concentrations used for Enzyme assay (0.1--10 microgram/ml). Gel filtration of the Enzyme in the presence of Ca2+ and monomeric concentrations of the substrate dihexanoylphosphatidylcholine showed that all the protein migrated as a 30 000 molecular weight species. Active Enzyme sedimentation velocity experiments using the same conditions gave s020,W=2.85 +/- 0.05 S, which compares favorably with the value obtained at mg/ml concentrations (3.11 S). These results confirm the results of Shen et al. (Shen, B.W., Tsao, F.H.C, Law, J.H. and Kézdy, F.J. (1975) J. Am. Chem. Soc. 97, 1205--1208).