Fig. 5.

Perpendicular-mode EPR spectra (A), parallel-mode EPR spectra (B), and visible-range absorption spectra (C) of Av1^{ΔnifZΔnifB(0)} (black lines), Av1^{ΔnifZΔnifB(+NifZ)} (green lines), Av1^{ΔnifZΔnifB(+Av2/ATP)} (pink lines), and Av1^{ΔnifZΔnifB(60′)} (blue lines). EPR and visible-range absorption spectra were measured at protein concentrations of 10 and 5 mg/ml, respectively, as described in Materials and Methods. The time-dependent change of the visible-range absorption spectra during P-cluster maturation is indicated by the red arrow. The g values of the EPR spectra are indicated. The perpendicular (B) and parallel-mode EPR signals (C) are integrated as percentages of that of Av1^{ΔnifZΔnifB(0)} (set as 50%).^¶