AMINO-ACID-SEQUENCE OF PIGUAMERIN, AN ANTISTASIN-TYPE PROTEASE INHIBITOR FROM THE BLOOD SUCKING LEECH HIRUDO-NIPPONIA

A serine-protease inhibitor of plasma kallikrein was screened and puri fied from a native Korean leech species, Hirudo nipponia. The peptide, named piguamerin, potently inhibited plasma and tissue kallikreins, a nd trypsin. Sequence analyses by automated Edman degradation revealed 48 amino acid residues and a molecular mass for the peptide of 5090 Da . Piguamerin is similar to antistasin-type inhibitors with the same sp acing of ten cysteine residues, but shows differences from hirustasin, antistasin and ghilanten at the residues surrounding Arg27, which is a common P1 reactive residue for these inhibitors. The purified inhibi tor modulated plasma clotting in tests of activated partial thrombopla stin time at nanomolar concentrations. The serine-protease inhibitor o f this leech may be involved in leech hematophagia.