Table 1.

Steady-state kinetic parameters for SARS-CoV-2 M^pro fluorescent substrates

Substrate	Sequencea	kcat/Km (M−1 s−1)
AKLQ–AMC	Ac-VKLQ ↓ {AMC}	18.5 ± 1.0
		24.5 ± 5.0b
nsp4–5-MCA	{MCA}-AVLQ ↓ SGFR{K(DNP)}K-NH2	14,190 ± 420
nsp4–5-EDANS	{DABCYL}-KTSAVLQ ↓ SGFRKM{E(EDANS)}-NH2	1960 ± 190
nsp4–5-FAM	{DABCYL}-KTSAVLQ ↓ SGFR{K(FAM)}K-NH2	2448 ± 85
nsp5–6-FAM	{DABCYL}-KSGVTFQ ↓ SAVK{K(FAM)}K-NH2	77.5 ± 4.2
nsp6–7-FAM	{DABCYL}-KKVATVQ ↓ SKMS{K(FAM)}K-NH2	68 ± 10
nsp8–9-FAM	{DABCYL}-KSAVKLQ ↓ NNEL{K(FAM)}K-NH2	6.01 ± 0.61
nsp10–12-FAM	{DABCYL}-KREPMLQ ↓ SADA{K(FAM)}K-NH2	4.74 ± 0.48
nsp14–15-FAM	{DABCYL}-KTFTRLQ ↓ SLEN{K(FAM)}K-NH2	38.0 ± 5.2

^aText in brackets denotes fluorophore or quencher, ↓ denotes cleavage site.

^bKinetic parameters determined from Michaelis–Menten plot. Each value reported as the mean ± 1 standard deviation, n = 3.