[Interaction of protein inhibitor from potato (protein with pI 7.3) with proteinases]

The interaction between protein inhibitor of serine proteinases from potato (protein with pI 7.3) and enzymes was investigated. The main complex present in mixtures of the inhibitor with trypsin, chymotrypsin or subtilisin contained one dimeric inhibitor molecule and one molecule of either enzyme. At high ratio enzyme/inhibitor the complexes were formed which contained more than one bound enzyme molecule. The interaction with enzymes does not include the proteolytic degradation of inhibitor with concomitant lowering of its molecular weight. The inhibitor obtained after the dissociation of inhibitor--chymotrypsin complex, preserve its capacity to form stable complexes with the enzyme.