Characterization of proteases from a stored product mite, Tyrophagus putrescentiae

Extracts of Tyrophagus putrescentiae feces exhibited higher (>50-fold) spec ific protease activity rates than those measured using mite body extracts f or the substrates azocasein, BApNa, SA(2)PPpNa, HA, and HPA. This suggests that trypsin, chymotrypsin, and carboxypeptidases A and B are involved in m ite digestion. Hydrolysis of the substrates ZAA(2)MNA and LpNa was only 3 t imes higher in fecal extracts, suggesting that levels of cathepsin B and am inopeptidases in the lumen of the digestive tract are low compared to the o ther enzymes, The hydrolysis of hemoglobin was only detected in body extrac ts indicating that cathepsin D is not a digestive protease in this species. Protease inhibitors of different specificity were tested in vivo to establ ish their potential as control agents. We found that development from larva e to adult was significantly retarded in larvae fed on brewers' yeast conta ining inhibitors of serine proteases, whereas no such effect was found with inhibitors of cysteine and aspartyl proteases, Interestingly, when dietary mixtures of serine protease, aminopeptidase and carboxypeptidase inhibitor s were fed to T. putrescentiae, a synergistic effect was observed that reta rded development, Several plant lectins were also tested, but none affected development. Arch. Insect Biochem, Physiol, 43:116-124, 2000, (C) 2000 Wil ey-Liss, Inc.