A Peptide Tag System for Facile Purification and Single-Molecule Immobilization

A peptide fusion tag and accompanying recombinant capture reagents have been developed oil the basis of the peptide-PDZ domain interaction and affinity clamps, a new class of affinity reagent. This system allows for single-step purification under mild conditions and stable capture of a tagged protein. The subnanomolar affinity, high force resistance (> 30 pN), small size (similar to 25 kDa, approximately one-sixth of the size of IgG), and monomeric nature of the affinity clamp are all superior features for many applications, in particular single-molecule measurements.