Enzyme Inhibition Assay: For enzymology studies of these compounds, recombinant guinea pig liver TGase was expressed in Escherichia coli and effectively purified (Gillet, S. M. F. G. et al J. N., Prot. Exp. & Purif. 2004, 33, 256). In addition to being easy to obtain in excellent yield and solubility, guinea pig liver TGase was chosen because it shows 80% homology with human tissue TGase (Aeschlimann, D.; Paulsson, M., Throm. Haemost. 1994, 71, 402) and may thus serve as a model for the evaluation of inhibitors of potential therapeutic utility.The IC50 values of synthetic analogues 14a-38a were determined from inhibition of the reaction of 54.4 mM of the chromogenic TGase substrate N-Cbz-Glu(γ-p-nitrophenyl ester)Gly with 0.010 U of recombinant guinea pig liver TGase as previously reported (Leblanc, A.; Gravel, C.; Labelle, J.; Keillor, J. W. Biochemistry 2001, 40, 8335) and described in detail in the Materials section below. The mode of inhibition was determined for the representative lead compound.
Drug metabolism assessed as reactivity with GSH by measuring glutathione adduct formation in DMSO-d6 at 12 mM after 10 mins by 1H NMR spectroscopy and mass spectrometry
Inhibition of guinea pig liver transglutaminase 2 using N-Cbz-Glu(gamma-p-nitrophenylester)Gly (AL5) substrate measured over 10 mins by UV-visible spectrophotometry
Competitive inhibition of human transglutaminase 2 using N-Cbz-Glu(gamma-p-nitrophenylester)Gly (AL5) substrate measured over 10 mins by UV-visible spectrophotometry based Michaelis-Menten analysis