Application of Schiff Base Copper(II) and Iron(III) Chelates to Site-Specific Cleavage of a Trypsin

Abstract

Amidine-containing Schiff base iron(III) and copper(II) chelates were prepared from α-amino acid, metal ion, and salicylaldehyde. These chelates behaved as specific inhibitors of trypsin, with K_i values in the range 10^-5-10^-6 M. Selective cleavage of the trypsin backbone resulting from specific binding of the chelate to the trypsin active site was investigated. Cleavage was observed when trypsin was incubated with amidine-containing copper(II) or iron(III) chelate, H₂O₂, and ascorbate. Examination of the three-dimensional structure of trypsin suggests that cleavage occurred at a peptide bond within the Gly₁₉₅-Ala₂₀₄ sequence.