title: Arginine modification in Kunitz bovine trypsin inhibitor through 1, 2-cyclohexanedione.
abstract: Arginine residues (5.5 out of 6) of the trypsin-kallikrein inhibitor from bovine organs (Kunitz inhibitor) were selectively modified by reaction with 1, 2-cyclohexanedione in sodium borate buffer, pH 9.0. The modified inhibitor is still highly active in inhibiting trypsin and chymotrypsin at 1:1 inhibitor: enzyme molar ratio and full inhibition was achieved at slightly higher molar ratio. The extent of correct refolding, upon reoxidation, of the reduced, arginine-modified inhibitor is diminished and regeneration of two arginines occurred under the reduction conditions. The stability constants and the standard-free energies of binding of the complexes between trypsin, or chymotrypsin, and the native, the arginine-modified and the reduced and reoxidized arginine-modified inhibitor have been determined from inhibitory assays.
mesh_terms: D000596:Amino Acids; D000818:Animals; D007611:Aprotinin; D001120:Arginine; D002021:Buffers; D002417:Cattle; D002918:Chymotrypsin; D003510:Cyclohexanes; D006868:Hydrolysis; D013696:Temperature; D014361:Trypsin Inhibitors
chemical_list: D000596:Amino Acids; D002021:Buffers; D003510:Cyclohexanes; D014361:Trypsin Inhibitors; D007611:Aprotinin; D001120:Arginine; D002918:Chymotrypsin