Proteinase Inhibitors from the Tropical Sea Anemone Radianthus macrodactylus: Isolation and Characteristic

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I. N. Sokotun^*, A. P. Il'ina, M. M. Monastyrnaya, E. V. Leychenko, A. A. Es'kov, S. D. Anastuk, and E. P. Kozlovskaya

Pacific Institute of Bioorganic Chemistry, Far East Branch of the Russian Academy of Sciences, pr. 100-let Vladivostoku 159, 690022 Vladivostok, Russia; fax: (4232) 314-050; E-mail: sokotun@piboc.dvo.ru

^* To whom correspondence should be addressed.

Received February 10, 2006; Revision received February 20, 2006

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Two new serine proteinase inhibitors (RmIn I and RmIn II) from the tropical sea anemone Radianthus macrodactylus have been isolated and characterized. The purification procedure includes polychrome-1 hydrophobic chromatography, Superdex^TM Peptide 10/30 FPLC, and Nucleosil C₁₈ reverse-phase HPLC. The molecular masses of RmIn I, RmIn II, and the complexes RmIn II/trypsin and RmIn I,II/alpha-chymotrypsin have been determined. The K_i values of RmIn I and RmIn II for trypsin and alpha-chymotrypsin have been determined. The polypeptides RmIn I and RmIn II are shown to be nontoxic and to exhibit antihistamine activity. The N-terminal amino acid sequences of RmIn I (GICSEPIVVGPCKAG-) and RmIn II (GSTCLEPKVVGPCKA-) have been determined. A high homology of the amino acid sequences is demonstrated for the proteinase inhibitors produced by such evolutionarily distant species as coelenterates, reptiles, and mammals.

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KEY WORDS: sea anemone, serine proteinase inhibitor, trypsin, chymotrypsin, inhibition constant, amino acid sequence

DOI: 10.1134/S0006297907030078

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