Purification and characterization of two serine protease inhibitors from the hemolymph of Mythimna unipuncta

Two serine protease inhibitors, trypsin inhibitor and a-chymotrypsin inhibi tor, were isolated from the hemolymph of Mythimna unipuncta. Mythimna tryps in and alpha -chymotrypsin inhibitors were purified by gel filtration and a nion-exchange chromatography. They displayed molecular masses of 52 kDa and 43 kDa, respectively, as determined by electrophoresis under reducing and nonreducing conditions on denaturing polyacrylamide gels. Their isoelectric points were evaluated by isoelectric focusing and two-dimensional electrop horesis. Their N-terminal sequences have been analyzed as APSDTTIAETLTITEEF FPD and FDESFGFQGPSTYEKTPLGEP, respectively. The role of these inhibitors i n the regulation of the defense reaction of the insect is discussed. (C) 20 01 Elsevier Science Ltd. All rights reserved.