Crotamine

Crotamine is a toxin present in the venom of the South American rattlesnake (Crotalus durissus terrificus). It was first isolated and purified by Brazilian scientist José Moura Gonçalves, and later intensively studied by his group of collaborators at the Medical School of Ribeirão Preto of the University of São Paulo (C.R. Laure, A. Haddad, F.L. De Lucca and J.R. Giglio, among others). It is a 42-long polypeptide containing 11 basic residues (9 lysines, 2 arginines) and 6 cysteines. It has also been isolated from the venom of North American prarie rattlesnake, Crotalus viridis viridis.

Crotamine has a number of biological actions: it acts on cell membrane's sodium channels, is slightly analgesic and is myotoxic, i.e., it penetrates the cells of muscles and promotes necrosis. Crotamine is homologous with other venom myotoxins and is similar to α-,β-defensins.

The aminoacid sequence and the 3D molecular structure of crotamine have already been determined.

YKQCHKKGGHCFPKEKICLPPSSDFGKMDCRWRWKCCKKGS—G

The gene and chromosome location responsible for its synthesis have been identified by the group led by Gandhi Rádis-Baptista, working at the Instituto Butantan, in São Paulo, Brazil. The mRNA has about 340 nucleotides and codifies a pre-crotamine, including the signal peptide, the mature crotamine, and a final lysine.