. Author manuscript; available in PMC: 2017 Sep 5.

Published in final edited form as: Biochemistry. 2016 Sep 19;55(39):5554–5565. doi: 10.1021/acs.biochem.6b00383

Table 2.

Inhibition Constants for Nicotinamide EcCTPS Inhibitors^a

inhibitor	IC₅₀,^b μM	IC₅₀^ox/IC₅₀^red
NADH	470 ± 40 (6)	3.7
NAD⁺	1700 ± 70 (2)
NADPH	450 ± 20 (3)	2.8
NADP⁺	1280 ± 50 (3)
1MDHN	140 ± 10 (7)	>28
1MeN	4000(est) (2)
ADP	4500(est) (2)

All reactions contained 200 nM EcCTPS, 1.5 mM ATP, 0.6 mM UTP, 0.2 mM GTP, and 10 mM glutamine.

IC₅₀ values were estimated by linear extrapolation of data points straddling 50% inhibition values. All nicotinamide inhibitors yielded nonlinear Hill plots, with limiting slopes of −0.89 ± 0.16 and −4.0 ± 1.0, at the low and high concentration ranges, respectively. The numbers of independent determinations used in the calculations are given in parentheses.