Photosensitized electron transport across lipid vesicle walls: enhancement of quantum yield by ionophores and transmembrane potentials
The photosensitized reduction of heptylviologen in the bulk aqueous phase of phosphatidylcholine vesicles containing EDTA inside and a membrane-bound tris(2,2'-bipyridine)ruthenium(2+) derivative is enhanced by a factor of 6.5 by the addition of valinomycin in the presence of K/sup +/. A 3-fold stimulation by gramicidin and carbonyl cyanide m-chlorophenylhydrazone is observed. The results suggest that, under these conditions, the rate of photoinduced electron transfer across vesicle walls in the absence of ion carriers is limited by cotransport of cations. The rate of electron transfer across vesicle walls could be influenced further by generating transmembrane potentials with K/sup +/ gradients inatthe presence of valinomycin. When vesicles are made with transmembrane potentials, interior more negative, the quantum yield of heptylviologen reduction is doubled, and, converseley, when vesicles are made with transmembrane potentials, interior more positive, the quantum yield is decreased and approaches the value found in the absence of valinomycin.
- Research Organization:
- Lawrence Berkeley Lab., CA
- OSTI ID:
- 6216508
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Journal Name: Proc. Natl. Acad. Sci. U.S.A.; (United States) Vol. 78:4; ISSN PNASA
- Country of Publication:
- United States
- Language:
- English
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Photosensitized electron transport across lipid vesicle walls
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ANTI-INFECTIVE AGENTS
ANTIBIOTICS
AZINES
BIOMIMETIC PROCESSES
BIPYRIDINES
CHEMICAL REACTIONS
COMPLEXES
DECOMPOSITION
DRUGS
ELECTRIC POTENTIAL
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
ESTERS
FERMIONS
HETEROCYCLIC COMPOUNDS
HYDROGEN PRODUCTION
LEPTONS
LIPIDS
MEMBRANE TRANSPORT
MEMBRANES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PHOTOSENSITIVITY
PYRIDINES
RUTHENIUM COMPLEXES
SENSITIVITY
TRANSITION ELEMENT COMPLEXES
VALINOMYCIN