[trypsin inhibition by sheep haptoglobin]

It was found that sheep haptoglobin causes non-competitive inhibition of trypsin. The enzyme inactivation is due to its interaction with haptoglobin. MetHb and thionine do not influence the efficiency of haptoglobin as a trypsin inhibitor. It is concluded that the haptoglobin molecule has a trypsin-binding site which differs from the sites responsible for the interaction with MetHb and thionine.