TABLE 3.

Kinetic constants for nucleotide incorporation by FMDV 3Dwt, 3D(K18E), 3D(K20E), 3D(K18A), 3D(K20A), and 3D(KAKA)

Enzyme	A on sym/sub-AUa			R on sym/sub-AUa			(kpol/Kd,ATP)ATP/(kpol/Kd,RTP)RTP (104)e
	Kd,ATP (μM)b	kpol (s−1)c	kpol/Kd,ATP (μM−1s−1)d	Kd,RTP (μM)b	kpol (10−3 s−1)c	kpol/Kd,RTP (10−6 μM−1s−1)d
3Dwt	44 ± 7	255 ± 9	5.8 ± 0.9	1604 ± 271	16 ± 2	10 ± 2	58 ± 15
3D(K18E)	62 ± 17	102 ± 6	1.6 ± 0.5	1587 ± 125	23 ± 1	14 ± 1	11 ± 4
3D(K20E)	76 ± 43	101 ± 11	1.3 ± 0.8	2144 ± 409	23 ± 3	11 ± 2	12 ± 8
3D(K18A)	85 ± 20	98 ± 5	1.2 ± 0.3	1087 ± 110	14 ± 1	13 ± 2	9 ± 3
3D(K20A)	814 ± 547	177 ± 50	0.2 ± 0.2	883 ± 99	9 ± 1	10 ± 2	2 ± 2
3D(KAKA)	434 ± 227	161 ± 25	0.4 ± 0.2	1421 ± 203	14 ± 1	10 ± 2	4 ± 2

^aKinetic parameters were obtained from the data shown in Fig. 3 according to the procedures detailed in Materials and Methods. A, adenosine; R, ribavirin.

^bK_d,NTP, dissociation constant for NTP binding.

^ck_pol, optimal polymerization rate constant.

^dk_pol/K_d,NTP, catalytic efficiency.

^e(k_pol/K_d,ATP)_ATP/(k_pol/K_d,RTP)_RTP, selectivity for discrimination in favor of incorporating the cognate nucleotide (AMP) instead of the nucleotide analogue (RMP).