Generation of Triplet and Cation-Radical Bacteriochlorophyll a in Carotenoidless LH1 and LH2 Antenna Complexes from Rhodobacter sphaeroides

The LH1 antenna complex and a native form of the LH2 complex were isolated from the carotenoidless R26 and R26.1 mutants of Rhodobacter sphaeroides by the use of a new detergent, sucrose monocholate. One-color, pump-and-probe transient Raman spectroscopy of these complexes using 351 nm, ∼50 ps pulses showed the generation of the triplet state of bacteriochlorophyll a (BChl a), whereas measurements using 355 nm, ∼12 ns pulses showed the generation of BChl a cation radical. Subpicosecond to nanosecond time-resolved absorption spectroscopy using 388 nm, 200 fs pulses for excitation showed rapid (