Figure 5

Binding mode of peptide substrates to FAP, DPPIV and PREP. (A) FAP active site (grey surface and pale green sticks) bound to modeled IPI substrate tripeptide (green sticks). (B) DPPIV active site (grey surface and pale cyan sticks) bound to IPI substrate tripeptide (cyan sticks). (C) FAP active site (grey surface and pale blue sticks) bound to modeled acetyl-VaPSQ substrate peptide (blue sticks). (D) Representative induced-fit docking model of PREP (grey surface and pale pink sticks) bound to acetyl-VAPSQ-amide substrate peptide (pink sticks). In all panels, red dashed lines indicate intermolecular and intra-substrate hydrogen bonds. (E) Comparison of cleavage rates by human FAP on VxPSQG peptide substrates containing various D-enantiomer residues at the P₂ position (xP).