A Novel Bioluminescent Protease Assay Using Engineered Firefly Luciferase

Table 3: IC₅₀ Determinations

Compound	IC₅₀ by CP₂₃₄-Luc/ENLYFQC	IC₅₀ by Protein Fusion Cleavage
ATA	N.D.	2.6 µM
NF-023	40 µM	2.3 µM
L-165,041	146 µM	90 µM

N.D.– not determined due to interference from the color of compound at high concentrations. ATA - aurintricarboxylic acid, NF-023 - 8,8'-[carbonylbis(imino-3,1-phenylenecarbonylimino)]bis(1,3,5-naphthalene-trisulfonic acid) hexasodium salt, L-165,041 - 4-[3-(4-Acetyl-3-hydroxy-2-propylphenoxy)propoxy]phenoxyacetic acid. IC50 values were estimated by plotting activity against the logarithm of compound concentration and fitting the data to a sigmoidal dose response curve using GraphPad Prism 4.