Isolation and Amino Acid Sequences of Polypeptide Toxins in the Caribbean Sea Anemone Condylactis passiflora

Abstract

The aqueous extract of the Caribbean sea anemone Condylactis passiflora was potently lethal to crabs and weakly hemolytic to animal erythrocytes but had no toxicity in mice. Three polypeptide toxins (named Cp I, II, and III) with lethal activity against crabs were isolated byion-exchange chromatography on DEAE-and CM-cellulose, gel filtration on Sephadex G-50, and reverse-phase HPLC on Nucleosil 300-7C₁₈. The minimum lethal doses against crabs were estimated to be 7.3 μg/kg (Cp I), 7.9 μg/kg (Cp II), and 10μ g/kg (Cp III). The amino acid compositions of the three toxins are closely related to each other; they are all rich in Asx, Ser, Gly, and half-Cys and are devoid of Met. In addition, it is noticeable that CpI and II contain an unusual amino acid, hydroxyproline. The complete amino acid sequences of CpI and II were determined. Both toxins have 47 amino acid residues, among which as many as 43 residues including all 6 half-Cys residues are homologous. Comparisonwith the sequences of the known sea anemone toxins reveals that CpI and II are analogous to type 1 long neurotoxins but have some significant changes in their sequences.