Electron spin resonance, electron spin echo, and electron nuclear double resonance investigations of the photoreduction yield of a series of alkylmethylviologens in dihexadecyl phosphate vesicles: Effect of added cholesterol

Journal Article · Thu Nov 28 04:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100177a099· OSTI ID:7072542

McManus, H J.D.; Kevan, L ^[1]

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1. Univ. of Houston, TX (United States)

The initial event in photosynthesis, photoinduced charge separation, takes place in a membrane bound proton/chlorophyll complex - the photosynthetic reaction center. An electron spin resonance (ESR), electron spin echo (ESE), and electron nuclear double resonance (ENDOR) investigation was performed on a series of alkylmethylviolgens which were solubilized in dihexadecyl phosphate (DHP) vesicles and rapidly frozen at 77 K. Photoreduction yields were measured by ESR, while ESE and matrix ENDOR were used to determine the location of the viologen radical in the lipid bilayer with respect to the water interface and the hydrocarbon interior, respectively. The effect of various concentrations on cholesterol on both the photoreduction yield and the location of the viologen probe within the DHP vesicle was measured. The ESE and ENDOR results indicate that the increased lipophilicity of the longer chained viologens effects deeper solubilization into the bilayer. This increased lipophilicity correlates with an enhancement of the photoreduction yield due to a reduced back electron transfer rate. Addition of cholesterol results in a disruption of the integrity of the vesicle interface and some increase in the photoreduction yield. This increase is mostly probably due to a decrease in effective interface charge density of the vesicle as a result of the intercalation of cholesterol molecules into the bilayer.

• OSTI ID: 7072542
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:24; ISSN JPCHAX; 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
AZINES
BIPYRIDINES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHOLESTEROL
DATA
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
ENDOR
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PYRIDINES
REDUCTION
RESONANCE
STEROIDS
STEROLS
YIELDS