Intrinsically disordered proteins and peptides play key roles in biology, but the lack of defined structures and high variability in sequence and conformational preferences has made targeting such systems challenging. Peptide-specific antibodies have been obtained by immunization or library selection, but these methods require considerable effort and disordered antigens are susceptible to degradation following injection. In silico design of proteins that can recognize unfolded peptides based on their sequence is thus an important challenge.