Automated synthesis of N-bromoacetyl-modified peptides for the preparation of synthetic peptide polymers, peptide-protein conjugates, and cyclic peptides.

A method to incorporate N-bromoacetyl moieties at the amino termini of synthetic peptides using a standard program with an automated peptide synthesizer has been developed. The N-bromoacetyl-derivatized peptides react well with sulfhydryl-containing proteins and with peptides containing cysteine residues. Autopolymerization or cyclization occurs by reaction of the free sulfhydryl of cysteine in a peptide with the bromoacetyl group and reactions can generally be controlled by controlling the concentrations of starting peptide in neutral pH buffers. Analytical methods for evaluating the polymers or cyclized peptides include gel filtration chromatography, reverse phase HPLC, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and amino acid analysis where the degree of reaction can be evaluated by quantifying the amount of S-carboxymethylcysteine formed after HCl hydrolysis. N-Bromoacetyl-derivatized peptides may be useful as reagents for potential peptide immunogens, vaccines, and therapeutics and as intermediates in the production of solid supports with peptide surfaces.