title: The accessory bacteriochlorophyll: a real electron carrier in primary photosynthesis.
abstract: The primary electron transfer in reaction centers of Rhodobacter sphaeroides is studied by subpicosecond absorption spectroscopy with polarized light in the spectral range of 920-1040 nm. Here the bacteriochlorophyll anion radical has an absorption band while the other pigments of the reaction center have vanishing ground-state absorption. The transient absorption data exhibit a pronounced 0.9-ps kinetic component which shows a strong dichroism. Evaluation of the data yields an angle between the transition moments of the special pair and the species related with the 0.9-ps kinetic component of 26 +/- 8 degrees. This angle compares favorably with the value of 29 degrees expected for the reduced accessory bacteriochlorophyll. Extensive transient absorbance data are fully consistent with a stepwise electron transfer via the accessory bacteriochlorophyll.
authors.affiliation: Technische Universität München, Physik Department E, Munich, Federal Republic of Germany.
authors.forename: T
authors.initials: T
authors.lastname: Arlt
authors.forename: S
authors.initials: S
authors.lastname: Schmidt
authors.forename: W
authors.initials: W
authors.lastname: Kaiser
authors.forename: C
authors.initials: C
authors.lastname: Lauterwasser
authors.forename: M
authors.initials: M
authors.lastname: Meyer
authors.forename: H
authors.initials: H
authors.lastname: Scheer
authors.forename: W
authors.initials: W
authors.lastname: Zinth