Coupling of peptides to protein carriers by mixed anhydride procedure.

Carboxyl groups of succinylated bovine serum albumin were activated by isobutylchloroformate in dimethylformamide solution. Subsequent reaction of the mixed anhydride with amino groups of the added peptide provided rapid and efficient coupling of peptide to protein. For different peptides the yield of coupling was equal to 40-100%. These values corresponded to 20-50 mol peptide bound/mol protein. Immunization of rabbits with these conjugates produced antisera to peptides with titers of 1:1000-1:3000 (estimated by enzyme-linked immunosorbent assay).