TABLE 4.

Summary of published results on P1 changes at HCV NS3-4A trans cleavage sites

Authors (yr)	Model	P1 residue	NS3 + NS4A			NS3 (no NS4A)
			Km (μM)	kcat (min−1)	kcat/Km (M−1/s−1)	Km (μM)	kcat (min−1)	kcat/Km (M−1/s−1)
Urbani et al. (1997)	E. coli-produced NS3 + NS4A-4B peptide	Cys	43 ± 4	1 ± 0.1	545	105 ± 20	0.3 ± 0.03	48
hCysa		54 ± 13	0.3 ± 0.01	96	312 ± 59	0.1 ± 0.01	5
		Abue	97 ± 29	0.17 ± 0.01	30	288 ± 30	0.03 ± 0.01	2
		Thr	235 ± 37	0.2 ± 0.01	15	244 ± 55	0.005 ± 0.001	0.3
		Val	153 ± 54	0.009 ± 0.001	1	NDb	ND	ND
		Ser	NCd	NC	NC	NC	NC	NC
Zhang et al. (1997)	Baculovirus-produced sc-NS3(1-631)/4A(1-54) + NS5A-5B peptide	Cysc	30	8.9	5,000
hCysc		70	1.0	240
Alac		240	0.5	35
		Thrc	710	1.2	28
		Metc	78	0.1	21
		Serc	530	0.1	3

^ahCys, l-homocysteine.

^bND, not determined (k_cat/K_m < 0.05 M⁻¹ s⁻¹).

^cSubstrate was modified at the P2 position (Cys to Ala) to minimize synthesis and oxidation problems.

^dNC, no cleavage.

^eAbu, α-aminobutyric acid.