ISOLATION AND CHARACTERIZATION OF GUAMERIN, A NEW HUMAN-LEUKOCYTE ELASTASE INHIBITOR FROM HIRUDO-NIPPONIA

A new human leukocyte elastase inhibitor was extracted and purified fr om a Korean native leech Hirudo nipponia. The inhibitor, called guamer in, has a molecular weight of 6,110 and shows inhibition constant (K-i ) of 8.1 x 10(-14) M. It is stable at a wide range of pH from 1 to 11 and heat-stable up to 90 degrees C. The complete amino acid sequence o f guamerin reveals a cysteine-rich polypeptide of 57 amino acid residu es that shows no similarity to any known elastase inhibitors but has 5 1% sequence homology with hirustasin, Guamerin has identical spacing o f 10 cysteine residues as antistasin-type serine proteinase inhibitors , but the P1 reactive site residue is Met(36) instead of Arg, The neig hboring sequence of the reactive site consists primarily of hydrophobi c amino acid residues, Based on examinations of the target proteinases and the reactive site specificity, guamerin is a new low molecular we ight protein that inhibits elastases.