<p><b>A.</b> NADH binding to 50 µM apoWrbA determined by UV spectroscopy. Difference absorbance at 265 nm (see text) is plotted <i>vs.</i> [NADH]. The solid line is intended only to guide the eye and does not represent a fit to the data. <b>B.</b> NAD binding to 200 µM apoWrbA detected by <sup>31</sup>P NMR. Spectra at 100, 200, 500, 1000 and 2000 µM NAD from bottom to top, respectively, are overlaid. The bracket with four arrows indicates the doublet pair characteristic of free NAD.</p
