Antibody to synthetic somatostatin-28(1-12): immunoreactivity with somatostatin in brain is dependent on orientation of immunizing peptide

Rabbits were immunized with synthetic peptides representing the neurotransmitter dodecapeptide somatostatin-28(1-12) (SANSNPAMAPRE) coupled to the carrier protein keyhole limpet hemocyanin (KLH) at either the amino or the carboxyl terminus. Although all rabbits produced high-titer antisera to immunizing peptide, as assayed by ELISA, only rabbits immunized with peptide coupled to carrier at the amino terminus yielded antibodies that bound to native somatostatin in mouse brain slices. This effect of peptide coupling orientation on epitope specificity of peptide antisera is likely to be significant to other investigators who use predetermined peptide sequences to generate immunohistochemical reagents.