Epitope-specificity of recombinant antibodies reveals promiscuous peptide-binding properties

Proteinpeptide interactions are a common occurrence and essential for numerous cellular processes, and frequently explored in broad applications within biology, medicine, and proteomics. Therefore, understanding the molecular mechanism(s) of proteinpeptide recognition, specificity, and binding interactions will be essential. In this study, we report the first detailed analysis of antibodypeptide interaction characteristics, by combining large-scale experimental peptide binding data with the structural analysis of eight human recombinant antibodies and numerous peptides, targeting tryptic mammalian and eukaryote proteomes. The results consistently revealed that promiscuous peptide-binding interactions, that is, both specific and degenerate binding, were exhibited by all antibodies, and the discovery was corroborated by orthogonal data, indicating that this might be a general phenomenon for low-affinity antibodypeptide interactions. The molecular mechanism for the degenerate peptide-binding specificity appeared to be executed through the use of 23 semi-conserved anchor residues in the C-terminal part of the peptides, in analogue to the mechanism utilized by the major histocompatibility complexpeptide complexes. In the long-term, this knowledge will be instrumental for advancing our fundamental understanding of proteinpeptide interactions, as well as for designing, generating, and applying peptide specific antibodies, or peptide-binding proteins in general, in various biotechnical and medical applications.