Figure 1

Cofactor arrangement in the RC of R. sphaeroides WT: PM and PL ─ bacteriochlorophyll a dimer, forming the primary electron donor, the Special Pair P, BA/B ─ accessory bacteriochlorophyll a, ΦA/B ─ bacteriopheophytin a, QA/B ─ quinone A and terminal electron accepting quinone B, Fe2+ ─ non-heme iron, Car ─ carotenoid. The electron is transferred only via the A-branch (black arrow). For details, see text.