Myotoxin

Myotoxin ( from ancient Greek. Μῦς mys, gene. Μυός myos, muscle ' and τοξίνη, ancient Greek pronounced toxins, the poisonous substance ', taken together muscle poison) is a snake venom peptide with muscle- paralyzing and destructive function. Especially in the venom of rattlesnakes (Crotalus ) there are various, homologous peptides that have this function.

History

The Brazilian scientist José Moura Gonçalves purified and identified in the 1950s, the first Myotoxin, Crotamin, from the venom of the Neotropical rattlesnake (Crotalus durissus terrificus ), a tropical rattlesnake is native to South America.

Structure and Function

Structurally very similar Myotoxine - all are small, basic peptides with molecular masses of 4.5 kDa, isoelectric points ( pI) of 9.8 and structure stabilized by three disulfide bridges - are present in the venom of pit vipers and vipers. The Myotoxine lead the prey to a muscle paralysis ( myotoxicity ) and prevent the escape. Within minutes, then death occurs by paralysis of the abdominal breathing and performs a further non -enzymatic mechanism for local death of muscle tissue ( myonecrosis ).

Sequence homology

Myotoxine from various snake venoms have been isolated mainly from the 1960s to 1980s and characterized. The comparison of their amino acid sequences reveals a high degree of sequence homology and the conservative in the intervals receipt of three cystine ( six cysteines that form three disulfide bridges: Cys4 - Cys36, Cys11 - Cys30 and Cys18 - Cys37 ), which stabilize the structure of the Myosinmoleküls ( yellow: cysteine; green: homologous (identical) amino acid sequence):