Figure 2.

(A) Protein tethering versus (B) peptide tethering. In protein tethering, native or nonnative reactive moieties such as cysteine residues direct fragments into nearby pockets. Fragment screening is often performed to target multiple pockets on the protein; multiple fragments are then linked together. In peptide tethering, the fragments are tethered to cysteine or another reactive group on the peptidomimetic. (C) Experimental setup: the peptide has a fluorophore, and fragments are covalently linked before individually incubating with the protein and determining fluorescence polarization (FP). The process can be repeated at multiple sites on the peptide.