May not function as a self-defense protein, but as a digestive enzyme, probably in the gut of the insect body. Inactive towards Micrococcus luteus. Active toward glycol chitin. Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins. Active at acidic pHs. Inactive above pH 7. Belongs to the glycosyl hydrolase 22 family.