As soon as the essential chemical features of the endothelins (twenty-one amino acids, two pairs of intrachain disulphide bridges, four cysteine residues at fixed positions (1, 3, 11 and 15), a hydrophobic tail and a terminal tryptophan residue) had been established it became apparent that their chemical profile is not unique (Lee and Chiappinelli 1988). To the contrary, it bears a remarkable and almost uncanny resemblance to that of the toxic peptides which Kochva and his colleagues (Kochva et al. 1982) and Bdolah et al. (1989) have isolated from the venom of the burrowing asp — a snake of the genus Atractaspis engaddensis. These toxic peptides are now known as sarafotoxins — after the common Hebrew name for the snake. Probably they deserve a place in the history books, because it was the venom of the burrowing asp which caused the premature, but self inflicted death of Cleopatra. Some idea of their potency can be gauged by the fact that ten nanograms per gram body weight is sufficient to cause sustained coronary vasospasm, cardiac arrest and death.
KeywordsLysine Polypeptide Leucine Val19 Threonine
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