[Show abstract][Hide abstract] ABSTRACT: The sea anemone Anemonia erythraea was found to contain polypeptide toxins with crab lethality as well as hemolysins. Three polypeptide toxins (AETX I, II and III) were isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on TSKgel ODS-120T. A geographic variation in toxin composition was suggested. The LD50 against crabs of AETX I, II and III were estimated to be 2.2, 0.53 and 0.28 microg/kg, respectively, but none of the toxins showed lethality in mice. The amino acid sequences of the three toxins were deduced from sequencings of the whole molecules and their enzymatic fragments. Amino acid analyses and molecular mass determinations supported the accuracy of the deduced sequences. AETX I, comprising 47 amino acid residues including 6 half-Cys residues, is an analog of sea anemone type I toxins. On the other hand, AETX II and III, which are highly homologous with each other, are quite distinct from the known sea anemone polypeptide toxins in that they are composed of 59 residues including 10 half-Cys residues. Interestingly, both toxins have sequence similarities with neurotoxins isolated from the Brazilian 'armed' spider Phoneutria nigriventer.
No preview · Article · May 1997 · Biochimica et Biophysica Acta
[Show abstract][Hide abstract] ABSTRACT: The aqueous extract of the sea anemone Radianthus crispus was potently lethal to crabs but had no toxicity in mice. A polypeptide toxin (named Rc I) was easily isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on TSKgel ODS-80Ts. Its minimum lethal dose against crabs was estimated to be 7.3 μg/kg. The complete amino acid sequence of Rc I was determined by sequence analyses of S-carboxamidomethylated toxin and its enzymatic fragments. Rc I comprises 47 amino acid residues and is characterized by the abundance of Asx, Gly, and half-Cys, the absence of Ala, Met, and Tyr, and the presence of an unusual amino acid, hydroxyproline. As compared with the sequences of the known sea anemone toxins, Rc I is an analogue of type 1 toxins, showing an especially high homology with Cp I (89%) and Cp II (81%) from the Caribbean sea anemone Condylactis passiflora.
[Show abstract][Hide abstract] ABSTRACT: The sea anemone (Actinia equina) was newly established to contain a polypeptide toxin (named Ae I) having lethal activity to crabs, besides the well-known cytolytic toxins (equinatoxins) of proteinic nature. Ae I, with a minimum lethal dose against crabs of 25 micrograms/kg, was easily isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on Nucleosil 300-7C18. Its amino acid composition is characterized by the abundance of Gly, the absence of Ala and the presence of Met. The complete amino acid sequence of Ae I was determined. Ae I has high sequence homology with type 1 sea anemone neurotoxins. Interestingly, the polypeptide chain of Ae I comprises 54 amino acid residues, being 5-8 residues longer than the known type 1 toxins having 46-49 residues.