Table 1.

Kinetic parameters for incorporation of nucleotides and analogs.

Nucleotide	kcat (s− 1)	Km (μM)	kcat/Km (μM− 1 s− 1)	D	Source
dTTP	34	4.7	7.2		Kellinger and Johnson [9]
AZT	29	3.5	8.3	0.9	Kellinger and Johnson [9]
d4T	1.4	1.2	1.2	6	Vaccaro et al. [9a]
dCTP	15	1.5	10		Kellinger and Johnson [10]
3TC	0.028	0.027	1	9.6	Kellinger and Johnson [10]
dCTP	23	30	0.8		Feng et al. [10a]
FTC	0.08	1.4	0.06	13	Feng et al. [10a]
dGTP	24	14	1.7		Ray et al. [11]
CBV	1	21	0.05	36	Ray et al. [11]
dATP	33	8.1	4.1		Suo and Johnson [11a]
ddATP	55	54	1	4	Suo and Johnson [11a]
PMPA	49	58	0.84	0.8	Suo and Johnson [11a]

The discrimination against each analog is defined by Eq. (1) with reference to the corresponding canonical base. Didanosine (ddI) is metabolized to ddATP in the cell. We repeat values for dCTP to normalize the results from different labs.