Amino acid sequence studies on cytolytic toxins from sea anemone Heteractis magnifica, Entacmaea quadricolor and Stichodactyla mertensii (Anthozoa).

The complete amino acid sequence of a cytolytic toxin, HmT, isolated from sea anemone Heteractis magnifica was determined. It is composed of 177 amino acid residues and lacks half-cystines. Partial N-terminal sequences of three other cytolysins from Entacmaea quadricolor (EnT) and Stichodactyla mertensii (SmT-1 and SmT-2) were also determined. Comparing these sequences with those of other sea anemone cytolysins, a high degree of homology was observed.

Amino acid sequence of two neurotoxins from the venom of the Egyptian black snake (Walterinnesia aegyptia).

The venom of the Egyptian black snake Walterinnesia aegyptia contains at least three toxins, which act postsynaptically to block the neuromuscular transmission of isolated rat phrenic nerve-diaphragm and chicken biventer cervicis muscle. The complete amino acid sequence of the two toxins, W-III and W-IV, consisting of 62 amino acid residues, was elucidated by Edman degradation of fragments obtained after Staphylococcus aureus protease and prolylpeptidase digestion. Although the toxins exhibit close structural homology to other short-chain postsynaptic neurotoxins from Elapidae venoms, toxin IV is unique by having a free SH-group (cysteine) at position 16. In position 35 of W-III, which is located at the tip of the central loop, threonine is replaced by lysine, which may alter the interaction of the toxin with the acetylcholine receptor, since the toxin is seven times less lethal than toxin W-IV.