Excitation dichroism of electric field modulated fluorescence yield for the identification of primary electron acceptor in photosynthetic reaction center

Journal Article · Thu Mar 07 04:00:00 EST 1991 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100158a027· OSTI ID:5719726

Ogrodnik, A; Eberl, U; Heckmann, R; Kappl, M; Michel-Beyerle, M E ^[1]; Feick, R ^[2]

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1. Technische Universitaet Muenchen, Garching (West Germany)
2. Max-Planck-Institut fuer Biochemie, Martinsried (West Germany)

In purple reaction centers, primary charge separation may lead to radical pair states which differ in the orientation of their dipole moments by {approx equal}31{degree} as revealed in the crystal structure analysis. Depending on the mechanism, two-step sequential or unistep superexchange, the primary radical pair states are either P{sup +}B{sup {minus}}H or P{sup +}BH{sup {minus}} (P, B, and H denoting the bacteriochlorphyll dimer, bacteriochlorophyll monomer, and bacteriopheophytin, respectively). Since this fact is reflected in the angular dependence of the primary charge separation rate in an external electric field, it also shows up in the excitation anisotropy of electric field induced changes of the fluorescence yield from the primary donor {sup 1}P{sup *}. This method has been applied to the fluorescence from reaction centers of Rb. sphaeroides, R-26, and an angle larger than 52{degree} between the dipole of the primary radical pair and the photoselected transition moment of the Q{sub x} transition of H{sub B} at the inactive pigment branch B has been determined at low temperatures. Allowing for considerable uncertainties in the directions of dipole and transition moments, this angle is only compatible with H{sub A} at the active branch A being the primary acceptor and excludes kinetic participation of B{sub A} located between P and H{sub A} in reaction centers embedded in a polymer membrane at temperatures below 180 K.

• OSTI ID: 5719726
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 95:5; ISSN JPCHA; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
DATA
DATA ANALYSIS
ELECTRIC FIELDS
ELECTRON TRANSFER
EMISSION SPECTROSCOPY
EXPERIMENTAL DATA
FLUORESCENCE SPECTROSCOPY
INFORMATION
LOW TEMPERATURE
NUMERICAL DATA
PHOTOSYNTHETIC REACTION CENTERS
SPECTROSCOPY