Stoichiometry of interaction of chicken ovoinhibitor with pancreatic trypsin, chymotrypsin and elastase I.

1. The interaction of chicken ovoinhibitor with pancreatic trypsin, chymotrypsin and elastase I was studied in the absence of substrate by affinity chromatography, electrophoresis and gel filtration. 2. It was found that ovoinhibitor has, at least, five separate and non-overlapping binding sites: two for trypsin, two for chymotrypsin and one for elastase. Most likely, all five sites may be occupied simultaneously. 3. Electrophoretic studies indicated that two binding sites for trypsin and probably also for chymotrypsin differ in their affinity toward the respective enzyme.