Initial electron-transfer in the reaction center from Rhodobacter sphaeroides.

• DOI: 10.1073/pnas.87.13.5168
• Publication Date: 2006-05-31T11:22:10Z
• Authors: W Holzapfel; U Finkele; W Kaiser; D Oesterhelt; H Scheer; H U Stilz; W Zinth
• Keywords: Rhodobacter sphaeroides; Femtochemistry; Rhodospirillaceae; Nanosecond; Purple bacteria

The initial electron transfer steps in the photosynthetic reaction center of purple bacterium Rhodobacter sphaeroides have been investigated by femtosecond time-resolved spectroscopy. experimental data taken at various wavelengths demonstrate existence least four intermediate states within first nanosecond. difference spectra intermediates and transient photodichroism are fully consistent with a sequential four-step model primary transfer: Light absorption special pair P leads to state P*. From excited donor P*, is transferred 3.5 +/- 0.4 ps accessory bacteriochlorophyll B. State P+B- decays time constant 0.9 0.3 passing bacteriopheophytin H. Finally, from H- quinone QA 220 40 ps.