Biochemistry and Pharmacology of the Crotoxin Complex

Crotapotin and the basic crotalus phospholipase A, which are the main components of the crotoxin complex, have been purified to homogeneity with respect to their behaviour on polyacrylamide gel electrophoresis, cellogel electrophoresis, immunoelectrophoresis, isoelectric focusing, and sedimentation equilibrium analysis.The isoelectric points were found to be 3.4 for crotapotin and 9.7 for the crotalus phospholipase A.The molecular weight of phospholipase A has been determined by gel filtration in 6 M guanidine · HCl (14500), by ultracentrifugation (15800), and by dodecylsulfate‐gel electrophoresis (15800). Phospholipase A consists of a single peptide chain intramolecularly crosslinked by eight disulfide bridges.The molecular weight of crotapotin was 8900 as shown by gel filtration in 6 M guanidine · HCl. Sedimentation equilibrium studies in 4 M guanidine · HCl gave a value of 6700. In solutions of lower ionic strength, the Mr, was 12500, indicating that crotapotin can exist as a dimer. In contrast the Mr of reduced and carboxamidomethylated crotapotin was much lower (4000–4500), in gel filtration experiments.Crotapotin consists of three peptide chains, held together by disulfide br