Table 1.

Enzyme cleavage activities of mutated substrate peptides

Substrate	Sequencea	Apparent kcat/Km (mM−1 min−1)b	(kcat/Km)rel
S12	SAVLQ ↓ SGF-CONH2	2.13 ± 0.20	1.00
P5L	LAVLQ ↓ SGF-CONH2	8.32 ± 0.25	3.90
P5T	TAVLQ ↓ SGF-CONH2	7.80 ± 0.24	3.66
P5V	VAVLQ ↓ SGF-CONH2	7.66 ± 0.30	3.59
P5A	AAVLQ ↓ SGF-CONH2	7.10 ± 0.24	3.33
P4L	SLVLQ ↓ SGF-CONH2	0.33 ± 0.04	0.15
P4T	STVLQ ↓ SGF-CONH2	3.14 ± 0.12	1.47
P4V	SVVLQ ↓ SGF-CONH2	5.21 ± 1.27	2.44
P3L	SALLQ ↓ SGF-CONH2	1.85 ± 0.06	0.87
P3T	SATLQ ↓ SGF-CONH2	2.53 ± 0.54	1.19
P3A	SAALQ ↓ SGF-CONH2	0.40 ± 0.03	0.19
P3K	SAKLQ ↓ SGF-CONH2	5.72 ± 0.45	2.68
P1′A	SAVLQ ↓ AGF-CONH2	4.36 ± 0.19	2.04
P1′G	SAVLQ ↓ GGF-CONH2	1.76 ± 0.09	0.83
P1′L	SAVLQ ↓ LGF-CONH2	NDc
S12	SAVLQ ↓ SGF-CONH2	12.68 ± 0.60*	1.000
P2M	SAVMQ ↓ SGF-CONH2	2.54 ± 0.07*	0.208
P2F	SAVFQ ↓ SGF-CONH2	0.58 ± 0.10*	0.046
P2I	SAVIQ ↓ SGF-CONH2	0.080 ± 0.011*	0.0063
P2V	SAVVQ ↓ SGF-CONH2	0.070 ± 0.009*	0.0056
P2A	SAVAQ ↓ SGF-CONH2	0.058 ± 0.008*	0.0046
P2R	SAVRQ ↓ SGF-CONH2	NDc,*
P1N	SAVLN ↓ SGF-CONH2	NDc,*
P1E	SAVLE ↓ SGF-CONH2	NDc,*
P1K	SAVLK ↓ SGF-CONH2	NDc,*
S21	TVVLQ ↓ SGF-CONH2	8.48 ± 1.32	3.98
S22	TVTLQ ↓ SGF-CONH2	5.58 ± 0.21	2.62
S23	VVTLQ ↓ SGF-CONH2	5.18 ± 0.74	2.43
S24	TVKLQ ↓ AGF-CONH2	9.18 ± 0.25	4.31

^aMutated residues are underlined. Cleavage sites are indicated by ↓.

^bThe concentration of SARS 3C-like proteinase is 5.41 μM for substrates without any label and that for substrates labeled with asterisk is 27.05 μM.

^cNot detectable in HPLC-based peptide cleavage assay.