A Reduced-Amide Inhibitor of Pin1 Binds in a Conformation Resembling a Twisted-Amide Transition State

作者：Xu Guoyan G; Zhang Yan; Mercedes Camacho Ana Y; Etzkorn Felicia A^*

来源：Biochemistry, 2011, 50(44): 9545-9550.

DOI：10.1021/bi201055c

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-Psi[CH2N]-Pro-2-(indol-3-yl)ethylarnine, 1 [R = fluorenylmethoxycarbonyl (Fmoc)] and 2 (R = Ac), of Pin1 were synthesized and bioassayed. Inhibitor 1 had an IC50 value of 6.3 mu M, 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 IC50 value of 12 mu M. The X-ray structure of the complex of 2 bound to Pin1 was determined to 1.76 angstrom resolution. The structure revealed that the reduced amide adopted a conformation similar to the proposed twisted-amide transition state of Pin 1, 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.

• 出版日期2011-11-8
• 单位美国弗吉尼亚理工大学(Virginia Tech)