CHARACTERIZATION OF A NOVEL ELASTASE INHIBITOR FROM A FAN CORAL

An acidic hydromethanolic extract of the tropical gorgonian Melithea c f. stormii exhibited anti-elastase activity. From the polypeptidic mix ture we isolated and purified to homogeneity a protein with a molecula r mass determined at 21,159 Da by Maldi/T of mass spectrometric analys is. The novel protein of marine invertebrate origin strongly inhibited amidolysis of Suc(Ala)(3)pNA by porcine pancreatic elastase (PPE) and was labelled iela melst. The N-terminal aminoacid sequence of its 39- first residues revealed the characteristics of a non-classical Kazal-t ype domain. Iela melst behaved as a reversible tight-binding inhibitor of PPE. The competitive inhibition followed Cha's mechanism A with an equilibrium dissociation constant, K-i calculated as 1.5 x 10(-9) M.