Crotamine-myotoxin family

General Activity
The crotamine-myotoxin family is composed of small basic peptides (42 to 45 residues) from rattlesnakes venom that possess multiple functions. These toxins act as cell-penetrating peptides (CPP), and as potent voltage-gated potassium channel (Kv) inhibitors. They also exhibit antimicrobial activities and provoke hind limb paralysis (Oguiura et al., 2005 ). Muscle necrosis has also been reported (Hayashi et al., 2008 ), but this activity may be due to a possible contamination. Hence, this activity should be re-tested .

The representative of this family, crotamine (from Crotalus durissus terrificus) has a compact fold with an α-helix and a two-stranded anti-parallel β-sheet. These are connected to each other and the remainder of the polypeptide chain by three disulfide bonds, which also form part of a central hydrophobic core. The global fold and the cysteine-pairing pattern of crotamine are similar to the β-defensin fold (Fadel et al., 2005 ). Hence, it is not surprising that β-defensins and crotamine share similar properties, including antibacterial activity and interaction with lipid membranes.