Table 2. Kinetic Parameters for Substrate Inhibition in Pol X-Catalyzed Steady-State Reactions.

						global fittingb
varied substrate	nonvaried substrate	inhibitor	Vmax (nmol/min)	Km (μM)	type of Inhibitiona	Vmax (nmol/min)	Km (μM)	KI (μM)	KII (μM)
dCTP	45(G)	none	0.49 ± 0.02	45 ± 5	UC	0.47	41		0.21
		50 nM 35dd(G)	0.35 ± 0.02	27 ± 2
		200 nM 35dd(G)	0.24 ± 0.01	23 ± 3
		500 nM 35dd(G)	0.14 ± 0.01	10 ± 1
45(G)	dCTP	none	0.46 ± 0.01	0.003 ± 0.001	C	0.45	0.0029	0.0064
		50 nM 35dd(G)	0.43 ± 0.02	0.029 ± 0.004
		200 nM 35dd(G)	0.45 ± 0.03	0.090 ± 0.012
		500 nM 35dd(G)	0.42 ± 0.08	0.182 ± 0.051
dATP	45(T)	none	1.5 ± 0.03	13 ± 2	NC	1.51	13	0.29	0.84
		50 nM 35dd(G)	1.4 ± 0.04	14 ± 2
		200 nM 35dd(G)	1.3 ± 0.04	19 ± 3
		500 nM 35dd(G)	0.91 ± 0.02	21 ± 2
45(T)	dATP	none	1.9 ± 0.06	0.030 ± 0.003	C	1.88	0.030	0.46
		50 nM 35dd(G)	1.9 ± 0.04	0.035 ± 0.002
		200 nM 35dd(G)	1.9 ± 0.09	0.043 ±  0.006
		500 nM 35dd(G)	1.7 ± 0.09	0.075 ± 0.009
dCTP	45(G)	none	0.52 ± 0.02	32 ± 5	C	0.51	35	48
		20 μM dATP	0.49 ± 0.02	55 ± 7
		200 μM dATP	0.56 ± 0.02	125 ± 13
		500 μM dATP	0.44 ± 0.05	299 ± 66
45(G)	dCTP	none	0.59 ± 0.03	0.006 ± 0.001	NC	0.57	0.0056	150	640
		50 μM dATP	0.51 ± 0.02	0.007 ± 0.001
		200 μM dATP	0.45 ± 0.02	0.010 ± 0.002
		500 μM dATP	0.31 ± 0.01	0.012 ± 0.002

^aC, UC, and NC refer to competitive, uncompetitive, and noncompetitive inhibition patterns, respectively.

^bErrors associated with global fitting are listed in Table S1 of the Supporting Information.