CHEMBL3705840

Inhibition Assay: The PPlase activity of recombinant CypA or D, produced by thrombin cleavage of GST-CypA or D, was determined by following the rate of hydrolysis of N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide by chymotrypsin. Chymotrypsin only hydrolyzes the trans form of the peptide, and hydrolysis of the cis form, the concentration of which is maximized by using a stock dissolved in trifluoroethanol containing 470 mM LiCl, is limited by the rate of cis-trans isomerization. CypA or D was equilibrated for 1 h at 5° C. with selected test article using a drug concentration range from 0.1 to 20 nM. The reaction was started by addition of the peptide, and the change in absorbance was monitored spectrophotometrically at 10 data points per second. The blank rates of hydrolysis (in the absence of CypA or D) were subtracted from the rates in the presence of CypA or D.