Position of Disulfide Bonds in Cobrotoxin.

摘要

The positions of four disulfide bonds in cobrotoxin were investigated. Cobrotoxin was digested with acid protease A, and the resulting five cystine peptides were separated by high-voltage electrophoresis on paper. The identification of the disulfide bridges was made by determining the amino acid composition of the corresponding cysteic acid peptides obtained after the oxidation of the single cystine peptides. The double cystine peptide, which contains the -CyS-CyS- linkage in sequence, from the acid protease A digest was further partially hydrolyzed with acid under conditions in which the disulfide bonds were stable. Five cystine peptides were obtained from which the two remaining disulfide bridges were established. The specificity of the acid protease A, the selectivity of acid hydrolysis, and the structure of cobrotoxin are discussed. (Author)