[Proteolytic enzymes bound to Bac. thuringiensis crystals].

It was demonstrated that crystals of entomopathogenic protein from Bac. thuringiensis contain admixture of proteinase either adhered to their surface on inconponated into crystal lattice defects. A proteolytic action, particularly when enhanced by crystal dissolution, causes progressive degradation of crystal proteins with molecular weights of 140 000--129 000 down to the components with smaller molecular weights. This may, at least, partially account for the contradictions in the literature data on crystal composition. Using synthetic peptide substrates and specific inhibitors, it was shown that the enzymes incorporated into crystals belong to serine and metalloproteases. The presence of leucine aminopeptidase was also noted. A method for enzyme separation from crystal has been developed.