Enzymatic Assay: Cyclophilin PPlase activity was measured at 20 C. by using the standard chymotrypsin coupled assay (Kofron J L, Kuzmic P, Kishore V, Colon-Bonilla E, Rich D H. Determination of kinetic constants for peptidyl prolyl cis-trans isomerases by an improved spectrophotometric assay. Biochemistry. 1991 Jun. 25; 30(25):6127-34). The assay buffer (25 mM Hepes, 100 mM NaCl, pH 7.8) and CypA, B or D (1900 nM stock solution) were pre-cooled to 4 C., to which then was added 5 uL of 50 mg/ml chymotrypsin in 1 mM HCl. The reaction was initiated by adding 20 uL of 3.2 mM peptide substrate (Suc-Ala-Ala-cis-Pro-Phe-pNA) in LiCl/TFE solution with rapid inversion. After a delay from the onset of mixing, the absorbance of p-nitroaniline was followed at 390 nM until the reaction was complete (1 min). The final concentration of LiCl in the assay was 20 mM; TFE was present at a concentration of 4% (v/v). Absorbance readings were collected every 1 s by spectrophotometer.
Inhibition of Cyclophilin D (unknown origin) activity preincubated for 15 mins followed Suc-AAPF-pNA substrate addition by chymotrypsin coupled based spectrophotometry assay
Inhibition of human recombinant cyclophilin D using Suc-AAPF-MCA as substrate preincubated for 1 hr followed by substrate addition measured per millisec for 2 mins by real time fluorescence analysis
Inhibition of cyclophilin D in human SK-N-SH cells assessed as reversal of Abeta (1 to 42 residues) mediated reduction of cytochrome c oxidase activity at 10 to 20 uM after 48 hrs by spectrophotometrical analysis relative to vehicle control
Inhibition of cyclophilin D in human SK-N-SH cells assessed as reversal of Abeta (1 to 42 residues) mediated decrease in ATP level after 48 hrs by bioluminescence assay
Inhibition of cyclophilin D in human SK-N-SH cells assessed as inhibition of Abeta (1 to 42 residues) mediated cell death at 10 to 20 uM after 48 hrs by MTT assay
Displacement of fluorescein labelled cyclosporine A derivative from human recombinant CypD (30 to 207 residues) expressed in Escherichia coli cells incubated for 90 mins by fluorescence polarization assay
Inhibition of CypD (unknown origin) PPIase activity using N-Suc-AAPF-p-nitroanilide as substrate preincubated with enzyme for 10 mins followed by chymotrypsin addition and further incubation for 4 mins followed by substrate addition
Potency index, ratio of IC50 of (R)-1-(4-aminobenzyl)-3-(2-(2-(2-(methylthio)phenyl)pyrrolidin-1-yl)-2-oxoethyl)urea to IC50 of compound for human recombinant CypD (30 to 207 residues) expressed in Escherichia coli cells incubated for 90 mins by fluorescence polarization assay