Table 1.

Catalytic efficiencies for M^pro substrates and analogs

Substrate	Sequencea	kcat (S−1)	Km (μM)	kcat/KM (M−1 s−1)	Fold changeb
nsp4/5	TSAVLQ/SGFRKM	0.52 ± 0.07	41 ± 9	1.3 ± 0.3 × 104	–
nsp8/9	RVVKLQ/NNELMP	0.013 ± 0.001	36 ± 6	3.6 ± 0.7 × 102	1.0
nsp8/9 N1′A	RVVKLQ/ANELMP	0.022 ± 0.001	22 ± 3	1.0 ± 0.1 × 103	2.9
nsp8/9 N2′A	RVVKLQ/NAELMP	0.034 ± 0.002	46 ± 5	7.5 ±0.8 × 102	2.1
nsp8/9 N1′D	RVVKLQ/DNELMP	–	–	–	–
nsp8/9 N2′D	RVVKLQ/NDELMP	0.0029 ± 0.0001	19 ± 1	1.6 ± 1.2 × 102	0.4

^aLys-DABCYL and Glu-EDANS and are appended to the N- and C-termini. Residues that differ from the wild-type sequence are bolded.

^bFold change = (k_cat/K_M) _{nsp8/9 analog} /(k_cat/K_M)nsp8/9