Studies on the partial synthesis of protein analogs by direct coupling to terminal homoserine lactone derivatives. Experiments with basic pancreatic trypsin inhibitor.

Treatment of basic pancreatic trypsin inhibitor (BPTI, I) with cyanogen bromide smoothly yields the chain cleaved derivative II. The utility of the seco-lactone (II) in the partial synthesis of protein analogues has been investigated. It is shown that the homoserine lactone ring is sufficiently reactive to combine directly with the radiolabelled synthetic peptide glycylglycylanine t-butyl ester in both aqueous and non-aqueous solution, leading to a BPTI analogue which has been purified and characterized.