Crotamine

Rattlesnakes, belonging to the genus Crotalus (Viperidae family), are geographically distributed from Canada to northern Argentina. Crotalus durissus has the broadest range of geographical distribution, in which 14 subspecies have been described (Campbell and Lamar,1989). Venoms from similar species of diverse geographical areas could differ in their constituents and consequently their toxicity (Salazar et al., 2007).
Crotamine, a polypeptide toxin, strongly basic protein (pI ~10.3), this protein was firstly isolated by Gonçalves and Polson (Gonçalves and Polson, 1947) from the venom of Argentinean rattlesnakes and designated by Gonçalves and Vieira (1950) from venom of Central and Southern Brazilian rattlesnakes. It belong to a group of closely related small basic polypeptide myotoxin (SBPM), commonly found in Crotalus venoms, and its contents very according to the species or the geographical location. Crotamine, a rattlesnake neurotoxin from de venom of the Brazilian snake Crotalus durissus terrificus is peptides rich in basic arginine and lysine residues. Is a 42 amino acid cationic polypeptide containing 11 basic residues and without free sulphydryl groups and reticulated by three disulfide bonds (Boni-Mitake et al., 2001). This toxin affects the functioning of voltage-sensitive sodium channels of skeletal muscle sarcolemma inducing a sodium influx, resulting in a depolarization and contraction of skeletal muscle, can be use for pharmaceutical.
Laser Raman spectroscopy studies (Kawano et al., 1982; Beltran et al., 1985; 1990), related to the determination of the secondary structure of crotamine, indicate that crotamine contain β-sheet, -helix and random coil structures. However, Siqueira et al. (2002) proposed a theoretical 3D structure for crotamine using computational calculation that was accomplished by homology modelling procedure and by intensive molecular dynamics simulations. The crotamine structure comprises a short N-terminal -helix and a small