Dr. Kim et Kw. Kang, AMINO-ACID-SEQUENCE OF PIGUAMERIN, AN ANTISTASIN-TYPE PROTEASE INHIBITOR FROM THE BLOOD SUCKING LEECH HIRUDO-NIPPONIA, European journal of biochemistry, 254(3), 1998, pp. 692-697
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.