Figure 3.

SDS/PAGE analysis of FNR in the fractions of Fd‐affinity chromatography. Recombinant maize L‐FNR (50 μL of 10 μm maize leaf FNR) was loaded on a small column (ca. 18 nmole of maize leaf Fd‐immobilized) and eluted with stepwise increasing concentrations of NaCl in the absence (control) and in the presence of NADPH, NADP⁺, or NAD⁺ at 1 mm or dithionite at 6 mm. The reason for the faint band observed in lanes 1 and 2, passed through the column under the conditions of control, NADP⁺, and NAD⁺, is not clear at present (A). Site‐directed mutants of maize L‐FNR were analyzed in the absence (control) and in the presence of NADPH at 1 mm (B). The numbering of the lanes 1–9 is the same as that of panel A. The addition of dithionite at 6 mm caused slight (0.16) changes in pH, but it did not significantly change the affinity of FNR for Fd, as observed at the bottom in panel A.