Inhibition of Hepatitis C virus genotype 1a NS3/4A protease A156T mutant expressed in Escherichia coli BL21 (DE3) cells assessed as substrate cleavage using Ac-DE-Dap(QXL520)-EE-Abu-psi-[COO]AS-C(5-FAMsp)-NH2 as substrate by plate reader analysis
Inhibition of Hepatitis C virus genotype 1a full length NS3/2K-NS4A protease R155K mutant using Ac-DED(Edans)EEAbupsi[COO]ASK(Dabcyl)-NH2 as substrate incubated for 10 mins prior to substrate addition by FRET analysis
Inhibition of Hepatitis C virus genotype 1a full length NS3/2K-NS4A protease D168V mutant using Ac-DED(Edans)EEAbupsi[COO]ASK(Dabcyl)-NH2 as substrate incubated for 10 mins prior to substrate addition by FRET analysis
Inhibition of Hepatitis C virus genotype 1a full length NS3/2K-NS4A protease A156T mutant using Ac-DED(Edans)EEAbupsi[COO]ASK(Dabcyl)-NH2 as substrate incubated for 10 mins prior to substrate addition by FRET analysis
FRET Assay: The protocol is a modified FRET-based assay (v_02) from In Vitro Resistance Studies of HCV Serine Protease Inhibitors, 2004, JBC, vol. 279, No. 17, pp 17508-17514. Inherent potency of compounds was assessed against A156S, A156T, D168A, and D168V mutants of the HCV NS3/4A 1b protease enzyme as follows: 10× stocks of NS3/4A protease enzyme from Bioenza (Mountain View, Calif.) and 1.13× 5-FAM/QXL™520 FRET peptide substrate from Anaspec (San Jose, Calif.) were prepared in 50 mM HEPES, pH 7.8, 100 mM NaCl, 5 mM DTT and 20% glycerol. 5 μL of each enzyme were pre-incubated in a Corning (#3573) 384-well, black, non-treated microtiter plate (Corning, N.Y.) for 30 min at 25° C. with a 0.5 μL volume of 50% DMSO and serially diluted compounds prepared in 50% DMSO. Protease reactions were started with the addition of 45 μL of the FRET substrate and monitored for 120 minutes at λex487/λem514 through Quad monochromoters in a Synergy4 plate reader from BioTek (Winooski, Vt.).
FRET Assay: The protocol is a modified FRET-based assay (v_03) developed to evaluate compound potency, rank-order and resistance profiles against wild type and C159S, A156S, A156T, D168A, D168V, R155K mutants of the HCV NS3/4A 1b protease enzyme as follows: 10× stocks of NS3/4A protease enzyme from Bioenza (Mountain View, Calif.) and 1.13× 5-FAM/QXL™520 FRET peptide substrate from Anaspec (San Jose, Calif.) were prepared in 50 mM Tris-HCl, pH 7.5, 5 mM DTT, 2% CHAPS and 20% glycerol. 5 μL of each enzyme were added to Corning (#3575) 384-well, black, microtiter plates (Corning, N.Y.) after spotting a 0.5 μL volume of 50% DMSO and serially diluted compounds prepared in 50% DMSO. Protease reactions were immediately started after enzyme addition with the addition of 45 μL of the FRET substrate and monitored for 60-90 minutes at λex485/λem520 in a Synergy4 plate reader from BioTek (Winooski, Vt.).