PURIFICATION OF A NOVEL, HEAT-STABLE SERINE-PROTEASE INHIBITOR PROTEIN FROM OVARIES OF THE DESERT LOCUST, SCHISTOCERCA-GREGARIA

A protease-inhibitor was isolated from mature ovaries of Schistocerca gregaria by a combination of trypsin-affinity chromatography and rever se-phase high performance liquid chromatography. It was characterized by aminoterminal amino acid sequencing using Edman degradation based a utomated microsequencing and by MALDI-TOF mass spectrometry, The N-ter minal sequence (Y)XAEXDELA(A)EEY(Y)Q(Q)X(I)(L)M (X being a Cys, an irr egular or modified amino acid) revealed no similarities with any other protease inhibitors isolated from invertebrate or vertebrate source. The 14 kDa inhibitor was found to be heat-stable. It shows potent inhi bitory activity toward bovine trypsin and chymotrypsin, but not toward pancreatic elastase. It is likely that the characterized inhibitor wi ll serve as an important tool for understanding its role in insect dev elopment. (C) 1997 Academic Press.