Table 2.

Kinetic parameters of rNTP incorporation and misincorporation into RNA by Polη using Mn²⁺ as cofactor.

Templating Nucleotide	Incoming Nucleotide	kcat (min−1)	KM (µM)	kcat/KM (min−1µM−1)	Relative Efficiency a	Discrimination1/f b
T	rATP	2.61 ± 0.14	2.51 ± 0.64	1.04
	rCTP	1.72 ± 0.06	19.4 ± 3.14	0.09	8.7 × 10−2	12
	rGTP	0.72 ± 0.03	44.6 ± 7.03	0.016	1.5 × 10−2	67
	rUTP	0.36 ± 0.02	261 ± 50.6	0.0014	1.3 × 10−3	769
G	rATP	0.06 ± 0.00	89.3 ± 17.7	0.0007	2.8 × 10−4	3571
	rCTP	4.68 ± 0.22	1.89 ± 0.42	2.48
	rGTP	0.31 ± 0.02	68.9 ± 14.9	0.0045	1.8 × 10−3	555
	rUTP	1.86 ± 0.04	199 ± 14.5	0.0093	3.8 × 10−3	263
C	rATP	0.10 ± 0.00	69.2 ± 11.9	0.0014	7.0 × 10−4	1429
	rCTP	1.03 ± 0.04	19.9 ± 3.74	0.052	2.6 × 10−2	38
	rGTP	5.07 ± 0.27	2.55 ± 0.63	1.99
	rUTP	0.16 ± 0.01	339 ± 49.4	0.0005	2.5 × 10−4	4000
A	rATP	0.05 ± 0.00	138 ± 26.2	0.0004	1.48 × 10−3	676
	rCTP	1.03 ± 0.07	17.5 ± 4.92	0.059	2.2 × 10−1	5
	rGTP	0.24 ± 0.01	55.9 ± 8.64	0.0043	1.6 ×10−2	63
	rUTP	3.51 ± 0.19	12.8 ± 2.25	0.27

^a Relative efficiency was calculated using the following equation: f_rel = (k_cat/K_M)_incorrect/(k_cat/K_M)_correct. ^b Inverse relative efficiency: 1/f_rel = (k_cat/K_M)_correct/(k_cat/K_M)_incorrect.