Charge separation in a reaction center incorporating bacteriochlorophyll for photoactive bacteriopheophytin

Journal Article · Fri Feb 22 04:00:00 EST 1991 · Science (Washington, D.C.); (United States)

DOI:https://doi.org/10.1126/science.2000491· OSTI ID:5426974

Kirmaier, C; Holten, D ^[1]; Gaul, D; DeBey, R; Schenck, C C ^[2]

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1. Washington Univ., St. Louis, MO (USA)
2. Colorado State Univ., Fort Collins (USA)

Site-directed mutagenic replacement of M subunit Leu{sup 214} by His in the photosynthetic reaction center (RC) from Rhodobacter sphaeroides results in incorporation of a bacteriochlorophyll molecule (BChl) in place of the native bacteriopheophytin (BPh) electron acceptor. Evidence supporting this conclusion includes the ground-state absorption spectrum of the (M)L214H mutant, pigment and metal analyses, and time-resolved optical experiments. The genetically modified RC supports transmembrane charge separation from the photoexcited BChl dimer to the primary quinone through the new BChl molecule, but with a reduced quantum yield of 60 (compared to 100 in wild-type RCs). These results have important implications for the mechanism of charge separation in the RC, and rationalize the choice of (bacterio)pheophytins as electron acceptors in a variety of photosynthetic systems. 38 refs., 6 figs., 1 tab.

• OSTI ID: 5426974
• Journal Information: Science (Washington, D.C.); (United States), Journal Name: Science (Washington, D.C.); (United States) Vol. 251:4996; ISSN SCIEA; ISSN 0036-8075
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
AROMATICS
BINDING ENERGY
CHEMICAL REACTIONS
DATA
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
EXPERIMENTAL DATA
FERMIONS
INFORMATION
LEPTONS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHOTOSYNTHETIC BACTERIA
PHOTOSYNTHETIC REACTION CENTERS
QUINONES
SYNTHESIS
VALENCE