Sarafotoxins S6: several isotoxins from Atractaspis engaddensis (burrowing asp) venom that affect the heart.

Three isotoxins, named sarafotoxins S6a1, S6b and S6c, with strong cardiotoxic activity were isolated from the venom of a snake, Atractaspis engaddensis. All three sarafotoxins are homologous peptides (four or less than four residue replacements) consisting of 21 amino acid residues. Their structure and activity are novel among snake venom components.