Table 1.

Pre-steady-state kinetic values for incorporation of 6-modified-3′-azido-ddGTP analogs by WT HIV-1 RT

Incorporation as an ‘A’ analoga
Nucleotide analog	kpol (s−1)	Kd (µM)	kpol/Kd (µM−1 s−1)	Selectivityb versus dATP
dATP	17.0 ± 2.1c	0.33 ± 0.05	52	–
3′-azido-ddATP	14.0 ± 5.6	0.32 ± 0.13	44	1.2
3′-azido-2,6-DA-P-TP	14.0 ± 4.9	0.29 ± 0.05	48	1.1
3′-azido-6-Cl-P-TP	2.7 ± 0.5	1.8 ± 1.0	1.5	35
3′-azido-6-AA-P-TP	2.1 ± 0.2	4.8 ± 2.3	0.44	118
3′-azido-6-MX-P-TP	2.8 ± 0.2	12.0 ± 1.2	0.23	226

Incorporation as a ‘G’ analogd
Nucleotide analog	kpol (s−1)	Kd (µM)	kpol/Kd (µM−1 s−1)	Selectivity versus dGTP
dGTP	17.3 ± 1.4	0.17 ± 0.05	102	–
3′-azido-2,6-DA-P-TP	0.16 ± 0.02	34 ± 14	0.005	20 400
3′-azido-6-Cl-P-TP	0.37 ± 0.04	0.92 ± 0.02	0.402	254
3′-azido-6-AA-P-TP	n.m.e	>50	n.m.	n.m.
3′-azido-6-MX-P-TP	0.22 ± 0.09	16.3 ± 4.3	0.013	7846

^a3′-ACAGGGACAAGCCCGCGGTGACGATCTCTTAAAGGTAAGACTGATTTTCCCAGACTC-5′; 5′-TCGGGCGCCACTGCTAGAGA: Sequence of the T/P substrate used to assess the 6-modified-3′-azido-ddGTP nucleotides as ‘A’ analogs.

^b Selectivity is (k_pol/K_d)^dNTP/(k_pol/K_d)^{3′-azido-ddNTP}

^cValues represent the mean ± standard deviation of three to four independent experiments

^d3′-ACAGGGACAAGCCCGCGGTGACGATCTCTCAAAGGTAAGACTGATTTTCCCAGACTC-5′; 5′-TCGGGCGCCACTGCTAGAGA: Sequence of the T/P substrate used to assess the 6-modified-3′-azido-ddGTP nucleotides as ‘G’ analogs

^en.m. Not measurable.

The rate of incorporation was so inefficient that accurate kinetic parameters could not be determined.