A crystalline synthetic peptide representing the epitope of a monoclonal antibody raised against synthetic interferon-a1 fragment 111 - 166

Abstract

The antigenic determinant recognized by the monoclonal antibody that had been raised against synthetic human interferonal (IFN-αl) fragment 111 – 166 [Arnheiter, H., Thomas, R. M., Leist, T., Fountoulakis, M., and Gutte, B. (1981) Nature (Lond.) 294, 278–280] and that cross-reacted with human IFN-αl, IFN-α2, and IFN-αA made in Escherichia coli, was localized to the region between residues 151 and 166 using synthetic COOH-terminal interferon fragments. In solid-phase radioimmunoassays neither the strongly hydrophilic COOH- terminal nonapeptide IFN 158 – 166 nor its mixtures with IFN 151 – 162 or IFN 149 – 158 showed any measurable interaction with the antigen binding site of the monoclonal antibody. For antibody binding, the full covalent structure of IFN 151 – 166 was required. Quantitatively very similar results were obtained with IFN 149–166 and IFN 143 – 166. The synthetic COOH-terminal hexadecapeptide of human IFN-α1 (IFN 151 – 166) could be crystallized.