FIG. 4.

Direct in vitro assay for NADH kinase activity. NADH kinase reactions were performed as described in Materials and Methods. Reaction mixtures contained 1 mM ATP, 4 μg of Pos5Δ17 and 0, 0.05, 0.1, 0.2, 0.5, 1.0, or 2.0 mM NAD⁺ (lanes 2 to 8, respectively), or 0, 0.05, 0.1, 0.2, 0.5, 1.0, or 2.0 mM NADH (lanes 9 to 15, respectively). The mixture in lane 1 did not contain enzyme. The origin of the thin-layer chromatogram and the relative mobilities of ATP, NADPH, and NADP⁺ are indicated with arrows.