Substrate-based design of reversible Pin1 inhibitors.

Human Pin1, a peptidyl−prolyl cis/trans isomerase with high specificity to -Ser/Thr(PO3H2)-Pro- motifs, is required for cell cycle progression. In an effort to design reversible Pin1 inhibitors by using a substrate structure based approach, a panel of peptides were applied to systematically analyze the minimal structural requirements for Pin1 substrate recognition. Pin1 catalysis (kcat/Km 1 mM). Substrates with chain lengths extending from either the P2 to P1‘ or the P1 to P2‘ subsite gave kcat/Km values of 100 mM-1 s-1 for Ala-Ser(PO3H2)-Pro and 38 mM-1 s-1 for Ser(PO3H2)-Pro-Arg. For both Pin1 and its yeast homologue Ess1, the optimal subsite recognition elements comprise five amino acid residues with the essential Ser(PO3H2) in the middle position. The resulting substrate Ac-Ala-...