Inhibition of Acyl Trypsins by Human Serum

Abstract

THERE is in blood a relatively high concentration of a specific trypsin inhibitor, the nature and identity of which are not fully established. In the presence of salts, it seems to form a stable stoichiometric addition complex with the enzyme, which is practically undissociated and enzymatically inactive¹. Similar complexes also prevail between the enzyme and a score of other natural inhibitors, whereby, in the case of ovomucoid, complex formation can be largely prevented by chemical modification of trypsin^2,3. Thus it was recently shown that the trypsin – ovomucoid complex has a dissociation constant K ₁ = 5.8 × 10⁻⁹ M, whereas acetylated trypsin is inhibited to a much lesser degree, the dissociation constant being higher³ by a factor of about 10².