Table 1.

Apparent TGT dissociation constants

RNA 3′end	RNAP	Fluorophore	KTGT (μM)
base\sugar			rRiboside	2′-Ddeoxy	3′-Deoxy
Adenine	Wild-type	6-MI i − 8 → i − 7	0.13 ± 0.04	2.1 ± 0.9	0.84 ± 0.38
Cytosine	Wild-type	6-MI i − 8 → i − 7	0.11 ± 0.04	3.8 ± 1.1	1.1 ± 0.7
Guanine	Wild-type	6-MI i − 8 → i − 7	0.18 ± 0.05	3.6 ± 1.0	1.3 ± 0.3
Uracil	Wild-type	6-MI i − 8 → i − 7	0.050 ± 0.001	2.8 ± 0.6	2.5 ± 0.2
Adenine	Wild-type	2-AP i + 1 → i + 2	0.15 ± 0.05	2.3 ± 0.6	1.7 ± 0.5
Adenine	Wild-type	2-AP i → i + 1 (RNA)	0.12 ± 0.10
Adenine	β′M932A	6-MI i − 8 → i − 7	0.65 ± 0.16
Adenine	β′R933A	6-MI i − 8 → i − 7	1.64 ± 0.45
Adenine	β′H936A	6-MI i − 8 → i − 7	0.94 ± 0.15

Errors are standard deviations of the best-fit estimates and were calculated by nonlinear regression of TEC fluorescence versus TGT concentration data using the model described in Supplementary Methods.