Effect of some chemical modifications of basic pancreatic trypsin inhibitor (BPTI) on its reaction with specific antibody.

Anti-BPTI-antibody inactivated the antitrypsin activity of basic pancreatic trypsin inhibitor. Esterification of BPTI with methanol did not affect its antitrypsin activity and precipitate formation with antibody. Acetylation, maleylation and hexa-S-carboxylation of BPTI completely inactivated the inhibitor reactivity and markedly diminished its precipitating ability. Performic acid oxidized BPTI and thermolysin digested BPTI lost its antitrypsin as well as antigenic activities. The both preparations as well as oxidized N-acetyl-L-cysteinyl-L-lysyl-L-alanylglycylglycyl-L-cysteine amide did not affect the complex formation between the inhibitor and antibody.