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. Author manuscript; available in PMC: 2008 Feb 29.
Published in final edited form as: Biochemistry. 2007 Aug 31;46(38):10971–10978. doi: 10.1021/bi7009822

Figure 6.

Figure 6

Titration curves for inhibition of uncoupled NADH oxidation and succinate-supported aerobic reverse electron transfer by NADH-OH. SMPs were preincubated in the standard reaction mixture with the indicated concentrations of NADH-OH for 15 min. The residual NADH oxidase (●, 100 μM NADH and 0.05 μg/mL gramicidin D) and reverse electron transfer (■, 1 mM NAD+ and 5 mM potassium succinate) activities were determined. The final concentration of SMPs in the assay mixture was 25 μg/mL. The SMP content in the preincubation mixture was 2 mg/mL. An activity of 100% corresponds to the specific activity (initial rate) of 0.8 and 0.1 (μmol/min)/mg of protein for NADH oxidase and reverse electron transfer, respectively. Longer preincubation of SMPs with NADH-OH did not change the titration curves.