FIGURE 5.

Heterogeneity of Phormidium cyt f-Phormidium PC BD complexes formed under different conditions. Five of the 10 complexes that were selected for detailed analysis as described in the Methods section are depicted unless otherwise indicated. The backbone ribbons were superimposed using GRASP. The heme groups on cyt f and the Cu and Zn ions as well as R88 are shown for PC. The ionic strength was 10 mM. (A) WT-PC minus Zn²⁺; (B) Phormidium cyt f-Phormidium PC complexes from Crowley et al. (2001). Twenty-five complexes were supplied by M. Ubbink. Five of these were chosen at random for display. Conditions were 10 mM sodium phosphate buffer (pH 6.0) + 1 mM Na-absorbate; (C) WT-PC plus Zn²⁺; and (D) (D42A + D43A + E52A + D57A-PC)-minus Zn²⁺.