Figure 7.

Excitation transfer in the bacterial photosynthetic unit. LH-II contains two types of BChls, commonly referred to as B800 (dark blue) and B850 (green), which absorb at 800 nm and 850 nm, respectively. BChls in LH-I absorb at 875 nm and are labeled B875 (green). P_A and P_B refer to the RC special pair, and B_A, B_B refer to the accessory BChls in the RC. The figure demonstrates the coplanar arrangement of the B850 BChl ring in LH-II, the B875 BChl ring of LH-I, and the RC BChls P_A, P_B, B_A, B_B. [Produced with the program vmd (25)].