Table 2.

Steady-state kinetic parameters of the 3′-5′ exonuclease activity of the wild-type and mutant derivatives of PolXBs.

Enzyme	kcat (min−1)	Km (nM)	Cat.eff. (min−1nM−1)	f
wild-type	0.51 ± (2.8 × 10−2)	431 ± 65	1.2 × 10−3	1
F440A	2 × 10−2 ± (1.8 × 10−3)	528 ± 145	3.8 × 10−5	32
R469A	5.8 × 10−2 ± (1 × 10−2)	1737 ± 579	3.3 × 10−5	36
R474A	4.8 × 10−3 ± (3 × 10−4)	94 ± 17	5.1 × 10−5	24
N498A	4.4 × 10−2 ± (4 × 10−3)	2318 ± 337	1.9 × 10−5	63
R503A	6.2 × 10−3 ± (9.8 × 10−4)	1041 ± 338	5.9 × 10−5	20
K545A	0.18 ± (1.1 × 10−2)	772 ± 132	2.3 × 10−4	5
Δ325-326	0.1 ± (5.5 × 10−3)	1500 ± 186	6.7 × 10−5	18

Data are means ± standard error of at least three independent experiments.

f: (Cat.eff.)_wt/(Cat. Eff.)_mutant