Primary charge separation in bacterial photosynthesis: oxidized chlorophylls and reduced pheophytin. [Chromatium vinosum]

Journal Article · Mon Dec 01 00:00:00 EST 1975 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.72.12.4956· OSTI ID:7306959

Fajer, J; Brune, D C; Davis, M S; Forman, A; Spaulding, L D

Bacteriopheophytin, the magnesium-free base of bacteriochlorophyll, undergoes reversible one-electron reduction in organic solvents to yield an anionic free radical with characteristic optical and electron spin resonance spectra. The reduction potential of bacteriopheophytin, E/sub 1/2/ approximately -0.55 V against a normal hydrogen electrode, compared to E/sub 1/2/ approximately -0.85 V for bacteriochlorophyll, renders it a likely electron acceptor in the primary charge separation of photosynthesis. Comparison of these data with picosecond optical changes recently observed upon pulsed laser excitation of bacterial reaction centers leads us to propose that bacteriopheophytin is indeed a transient electron acceptor and that the primary charge separation of bacterial photosynthesis occurs between the bacteriochlorophyll complex P/sub 870/ and bacteriopheophytin to yield the radicals of the oxidized chlorophyll dimer cation and reduced pheophytin anion.

• Research Organization: Brookhaven National Lab. (BNL), Upton, NY (United States)
• OSTI ID: 7306959
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 72:12
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BACTERIA
PHOTOSYNTHESIS
CHLOROPHYLL
CHEMICAL REACTIONS
PIGMENTS
CHEMICAL PROPERTIES
LASERS
OXIDATION
CARBOXYLIC ACIDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PORPHYRINS
SYNTHESIS
550200* - Biochemistry