The blockage of the carboxyl groups of a pancreatic trypsin inhibitor (inhibitor of Kunitz) has been performed with a water-soluble carbodiimide and glycine ethyl ester. The inhibitor has five carboxyl groups located on residues Asp(3), Glu(7), Glu(49), Asp(50) and Ala(58). When the reaction is carried out on native inhibitor or on inhibitor treated with 8 M urea, approximately 3 moles of glycine ethyl ester are introduced but 4, 3 residues can be incorporated into performic acid oxidized inhibitor. Fully active derivatives with a complete substitution of the C-terminal residue can be obtained. It may be concluded that the C-terminal carboxyl group is not involved in the binding with trypsin.
Chauvet
J
J
Laboratoire de Chimie Biologique, Faculté des Sciences de Paris, France
Acher
R
R
Role des groupes carboxyles de l'inhibiteur de kunitz dans son union avec la trypsine.