title: A reduced-amide inhibitor of Pin1 binds in a conformation resembling a twisted-amide transition state.
abstract: The mechanism of the cell cycle regulatory peptidyl prolyl isomerase (PPIase), Pin1, was investigated using reduced-amide inhibitors designed to mimic the twisted-amide transition state. Inhibitors, R-pSer-Ψ[CH(2)N]-Pro-2-(indol-3-yl)ethylamine, 1 [R = fluorenylmethoxycarbonyl (Fmoc)] and 2 (R = Ac), of Pin1 were synthesized and bioassayed. Inhibitor 1 had an IC(50) value of 6.3 μM, which is 4.5-fold better for Pin1 than our comparable ground-state analogue, a cis-amide alkene isostere-containing inhibitor. The change of Fmoc to Ac in 2 improved aqueous solubility for structural determination and resulted in an IC(50) value of 12 μM. The X-ray structure of the complex of 2 bound to Pin1 was determined to 1.76 Å resolution. The structure revealed that the reduced amide adopted a conformation similar to the proposed twisted-amide transition state of Pin1, with a trans-pyrrolidine conformation of the prolyl ring. A similar conformation of substrate would be destabilized relative to the planar amide conformation. Three additional reduced amides, with Thr replacing Ser and l- or d-pipecolate (Pip) replacing Pro, were slightly weaker inhibitors of Pin1.
authors: Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
authors: Guoyan G
authors: GG
authors: Xu
authors: Yan
authors: Y
authors: Zhang
authors: Ana Y
authors: AY
authors: Mercedes-Camacho
authors: Felicia A
authors: FA
authors: Etzkorn
mesh_terms: D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010084:Oxidation-Reduction; D019696:Peptidylprolyl Isomerase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D011759:Pyrrolidines / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000577:Amides; D004791:Enzyme Inhibitors; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D011759:Pyrrolidines; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C032519:pyrrolidine