Pest insects such asHelicoverpaspp. frequently feed on plants expressing protease inhibitors. Apparently, their digestive system can adapt to the presence of protease inhibitors. To study this, a trypsin enzymewas purified from the gut of insects that were raised on an inhibitor-containing diet. The amino-acid sequence of this enzyme was analysed by tandem MS, which allowed assignment of 66% of the mature protein amino acid sequence. This trypsin, called HzTrypsin-S, corresponded to a known cDNA sequence fromHelicoverpa. .
