. Author manuscript; available in PMC: 2009 Aug 18.

Published in final edited form as: Nat Struct Mol Biol. 2009 Jan 18;16(2):212–218. doi: 10.1038/nsmb.1540

Table 1. Kinetic analysis of PV RdRp, HIV-1 RT, RB69 DdDp and T7 DdRp supports general acid catalysis in nucleotidyl transfer.

Parameter Measured	PV RdRp		HIV RT		RB69 DdDp		T7 DdRp
	WT	K359L	WT	K220L	WT	K560L	WT	K631L
k_pol (s⁻¹)	50 ± 5	1 ± 0.1	60 ± 5	0.3 ± 0.1	200 ± 10	0.10 ± 0.01	60 ± 5	0.6 ± 0.1
K_d,app (μM)^a	200 ± 20	700 ± 80	7 ± 1	5 ± 2	40 ± 5	1000 ± 100	300 ± 30	5.0 ± 1.0 × 10^4c
SDKIE^b	3.0 ± 0.3	2.5 ± 0.3	2.2 ± 0.4	1.8 ± 0.4	4.2 ± 0.2	1.8 ± 0.2	5.2 ± 0.5	2.6 ± 0.5^c
PI^d	2	1	2	1	2	1	2	nd^e

K_d,app is for (d)ATP (Supplementary Methods).

SDKIE is solvent deuterium kinetic isotope effect ²⁸, calculated as k_obs in H₂O/k_obs in D₂O at saturating [(d)ATP].

K_d,app, k_pol and SDKIE values listed for T7 K631L were obtained by using data collected with 80 mM ATP, a sub-saturating concentration.

PI is proton inventory ²⁹, calculated from a plot of kn/k0 as a function of n. The data were fit to a modified Gross-Butler equation for either a two-proton-transfer model (eq. 1) or for a one-proton-transfer model (eq. 2). The value reported is the proton-transfer-model that best fits the data.

not determined