Trypsin inhibition by tapeworms: antienzyme secretion or pH adjustment?

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Science  01 Apr 1983:
Vol. 220, Issue 4592, pp. 79-81
DOI: 10.1126/science.6828882


The tapeworm Hymenolepis diminuta releases proteins that inhibit trypsin activity. These proteins may be either antienzymes or nonspecific macromolecules that interfere with trypsin. Saline solutions with initial pH values ranging from 5.5 to 10.0 were all acidified to pH 5.0 by tapeworms. If the initial pH was lower than 5.0, it was raised. Because trypsin activity is inhibited at pH 5.0, this intestinal parasite can protect itself from digestion by regulating its environmental pH or releasing trypsin inhibitors, or both.