Effect of hydrophobization of basic pancreatic proteinase inhibitor on theinhibition 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 try psin and human leukocyte elastase (HLE) was studied. Kinetic constants of i nteraction with trypsin and inhibition constants of both enzymes were deter mined. Hydrophobization of BPTI had virtually no effect on its high affinit y for trypsin. The coupling of cis-unsaturated oleoyl radicals to the inhib itor molecule significantly increased the efficiency of HLE inhibition, whe reas the coupling of saturated stearoyl radicals completely canceled the an ti-elastase activity and in some cases promoted the substrate hydrolysis.