Polarized Absorption Spectra of the B800–850 Light-Harvesting and the RC-B875 Reaction Center Complexes from Purple Bacteria

The B800–850 light harvesting complex of Rps. acidophila and the RC—B875 reaction center complex of Rps. palustris were crystallized in presence of detergents. The crystals were obtained by vapour diffusion technique using polyethylene glycol 1000 (1,2). For spectroscopic studies, the B800–850 and the RC—B875 complexes were crystallized on thin cover slides, allowing the crystals to grow to sufficient size in two dimensions. Sealed by a second cover slide, the crystals were mounted on a goniometer sample holder in a micro-spectrophotometer (3) built in our laboratory.