FIG. 3.

Pre-steady-state burst kinetics showing incorporation of dGMP (A) or DXG-monophosphate (B) into a DNA-DNA 30/45-mer primer-template by HIV-1 RT. A preincubated mixture of DNA-DNA 30/45-mer primer-template (300 nM) and HIV-1 RT (active site concentration, 100 nM) was mixed with 75 μM dGTP (A) or 30 μM DXG-TP (B) in 10 mM MgCl₂ containing buffer to start the reaction. The reactions were quenched at the indicated time interval with EDTA (0.3 M) and were analyzed by sequencing gel electrophoresis. The solid line represents the fit to the burst equation as described in the text. The curves in panel A represent fits with A equal to 101 ± 9 nM, k_obsd equal to 15 ± 2 s⁻¹, and k_ss equal to 0.36 ± 0.03 s⁻¹ for dGTP, and the curves in panel B represent fits with A equal to 81 ± 4 nM, k_obsd equal to 11.3 ± 0.1 s⁻¹, and k_ss equal to 0.10 ± 0.01 s⁻¹ for DXG-TP.