The present invention provides a universal peptide-binding scaffold. This scaffold is used to bind a target. The target can be a peptide or peptides of interest (for example, peptides associated with a disease state) or can represent the entire proteome. The target can be either protein fragments prepared by enzymatic digestion of the entire proteome or N- or C-terminal short sequences exposed by chemical denaturation of the entire proteome (unfolded proteins). The universal peptide-binding scaffold can be tailored to specifically bind a target using the methods described herein.