Fig. 1

Mitochondrial ubiquinone-binding sites in A the reference and B the Phe18Leu variant cytochrome b. (Q_o) intermembrane side ubiquinone; (Q_i) matrix side ubiquinone; (b_H) high potential heme b; (b_L) low potential heme b. The distances are shown in ångströms. Both Phe18 and Phe220 are probably able to interact via π–π stacking with the quinol ring of ubiquinone Q_i. An in silico Phe18Leu mutation in the coordinate file 1ntz.pdb and visualization were performed using the PyMol software