Interchain disulfide bonds in crotamine self-association.
Crotamine, a basic neurotoxic protein, was isolated from the venom of the Southern Brazilian rattlesnake (Crotalus durissus terrificus) by gel filtration. The isolated protein showed a single band on PAGE at pH 4.5 and 7% (w/v) gel concentration, but two or more bands at 14% gel concentration, even in the presence of 4 M urea. After reduction and carboxymethylation, however, a single band was again detected. SDS-PAGE as well as ultracentrifugal analysis of the native (NC) and of the reduced and carboxymethylated (RCC) crotamine revealed a molecular weight of 4,500-5,000 for RCC and 9,000-10,000 for NC. Both components of a two-band crotamine preparation were isolated by preparative PAGE and characterized. Their particular electrophoretic mobility was retained. Their amino acid composition. N-terminal residue, and apparent toxicity were the same as those of the original sample. It was concluded that crotamine is able to form a dimer of 9,760 Da with two identical polypeptide chains crosslinked by interchain disulfide bonds and a shape not very far from spherical, which covalently binds extra subunits of 4,880 Da each.
Teno
A M
AM
Departamento de Química Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Brasil.
Vieira
C A
CA
Santoro
M M
MM
Neves
A G
AG
Giglio
J R
JR
D000818:Animals; D003435:Crotalid Venoms / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity; D004220:Disulfides; D046911:Macromolecular Substances; D051379:Mice; D011487:Protein Conformation
D003435:Crotalid Venoms; D004220:Disulfides; D046911:Macromolecular Substances; C010563:crotamine