1976 Volume 80 Issue 6 Pages 1293-1297
The reactive site peptide bend of the eggpla.zt inhibitor against trypsin [EC 3. 4. 21. 4] was identified by chemical modifications with 1, 2-cyclohexanedicne, 2, 4, 6-trinitrobenzencsulfcnic acid., acetic anhydride and glyoxal, and by sequential treatments with trypsin and carboxy-peptidase B [EC 3. 4. 12. 3]. The inhibitor was significantly inactivated by chemical modifica-tions of arginine residues, but was riot affected by lysine modifications. Free arginine was released from the trypsin-modified inhibitor by carboxypeptidase B digestion, accompanied by a marked less of inhibitory activity. A serine residue was newly exposed as the N-terminal amino acid of the inhibitor after modification with trypsin. The reactive site of the inhibitor against trypsin was concluded to be an arginylseryl bond. The inhibitor was completely inactivated by full rcducticn of its disulfide bonds.
