α-Carbon model of the lumen-side extrinsic polypeptide of turnip (French, “le navet”; German, “die Steckrübe” or “der Kohlrabi”) cytochrome f (SDS-PAGE in Fig. 5) showing the large and small domains of the cytochrome, the heme, and residues Lys-145 and Lys-187 in the large and small domains, and Arg-250 at the C-terminus that are separated by 33, 28, and 45 Å, respectively, from the heme iron.