Effect of hydrophobization of basic pancreatic proteinase inhibitor on the inhibition of bovine trypsin and human leukocyte elastase.

The effect of modification of basic pancreatic trypsin inhibitor (BPTI) by derivatives of fatty acids (oleic, stearic) on the inhibition of bovine trypsin and human leukocyte elastase (HLE) was studied. Kinetic constants of interaction with trypsin and inhibition constants of both enzymes were determined. Hydrophobization of BPTI had virtually no effect on its high affinity for trypsin. The coupling of cis-unsaturated oleoyl radicals to the inhibitor molecule significantly increased the efficiency of HLE inhibition, whereas the coupling of saturated stearoyl radicals completely canceled the anti-elastase activity and in some cases promoted the substrate hydrolysis.