Chlorophyll-quinone photochemical electron transfer in liposomes

Journal Article · Tue Sep 01 04:00:00 EDT 1981 · BioScience; (United States)

DOI:https://doi.org/10.2307/1308226· OSTI ID:5177558

Hurley, J K; Castelli, F; Tollin, G

The study described involves the reduction of electron acceptors (quinones) by photoexcited Chloroplasts (Chl). Chl a (from spinach) is incorporated into phosphatidylcholine (either synthetic or from hen egg yolks) liposomes suspended in 10 mM phosphate buffer (pH 7.0). The quinones are either present during liposome formation or added later, depending upon their water solubility. The measurement technique employed is laser flash photolysis. A pulsed nitrogen laser pumps a dye laser, which delivers a short light flash (10 ns) to the sample at a wavelength (655-660 nm) within an absorption band of Chl. This raises Chl to an excited singlet level, which can rapidly cross to the lowest excited triple level (/sup 3/Chl). From this state Chl can transfer an electron to acceptors such as quinones, resulting in the formation of the Chl cation radical (Chl./sup +/) and the semiquinone anion radical (Q./sup +/). Transient absorbance changes ocurring within the sample cell are monitored and can be attributed to processes such as excited state quenching (of /sup 3/Chl by Q) and radical product formation and decay. (JMT)

• Research Organization: Univ. of Arizona, Tucson
• OSTI ID: 5177558
• Journal Information: BioScience; (United States), Journal Name: BioScience; (United States); ISSN BISNA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
551001 -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AROMATICS
BIOLOGICAL MODELS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CHLOROPHYLL
CONVERSION
DECOMPOSITION
ELECTRON TRANSFER
ENERGY CONVERSION
FOOD
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
KINETICS
LASERS
LIPOSOMES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANOIDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
PHOTOLYSIS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
QUINONES
RADICALS
REACTION KINETICS
SOLAR ENERGY CONVERSION
SPINACH
SYNTHESIS
VEGETABLES