FIGURE 1.

Formation of 1,2-GDN from GTN by WT- and E268Q-ALDH2 in the absence and presence of NAD. A, effect of GTN concentration. Purified proteins (4 μg each) were incubated at 37 °C for 10 min in 0.2 ml phosphate buffer (pH 7.4) containing increasing concentrations of [¹⁴C]GTN, 3 mm MgCl₂, and 2 mm DTT in the absence and presence of 1 mm NAD. B, effect of protein concentration. Purified proteins (20–200 μg each) were incubated at 37 °C for 1 min in 0.2 ml of phosphate buffer (pH 7.4) containing 0.1 mm [¹⁴C]GTN, 3 mm MgCl₂, and 2 mm DTT in the absence and presence of 1 mm NAD. 1,2- and 1,3-GDN were extracted and quantified by radio thin layer chromatography as described previously (14). The data are the mean values ± S.E. of three independent experiments.