[Amino acid sequence of neurotoxins IV and V from the sea anemone Radianthus macrodactylus].

Amino acid sequences of neurotoxins RTX-IV and RTX-V isolated from the sea anemone Radianthus macrodactylus were determined by the automated Edman degradation; their polypeptide chains consist of 48 and 47 amino acid residues, respectively. For identification of tryptophan-30 in toxin RTX-IV, its trypsin and chymotrypsin digests were investigated. Amino acid sequences of the above toxins show that they belong to a new structural class and that C-terminal positive charge and tyrosine-25 are important for toxic activity of sea anemone polypeptides.