CHLOROPHYLL PHOTOSENSITIZED ELECTRON TRANSFER REACTIONS IN LIPID BILAYER VESICLES: VECTORIAL ELECTRON TRANSFER ACROSS THE BILAYER FROM REDUCED CYTOCHROME c IN THE INNER COMPARTMENT TO OXIDIZED FERREDOXIN IN THE OUTER COMPARTMENT

Zhan-Gong Zhao, Gordon Tollin

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

A negatively charged large unilamellar vesicle system containing a membrane‐bound photo‐sensitizer (chlorophyll, Chi), a reduced redox protein [cytochrome c, cyt c(red)] in the inner aqueous compartment, an oxidized redox protein [ferredoxin, Fd(ox)] in the outer aqueous compartment, and propylene diquat (PDQ2+) as a mediator, was investigated using both flash and steady‐state photolysis techniques. The results demonstrate that the light‐generated triplet state of Chi (3Chl) was initially quenched by PDQ2+ at the outer membrane surface to form Chi cation radical (Chl+) and the reduced diquat (PDQ+). This was succeeded by a biphasic recombination between Chi+ and PDQ+. The slow phase of the recombination process, which represents reverse electron transfer between Chl+ and those PDQ+ molecules which escaped from the membrane surface, could be suppressed effectively both by the reduction of Chl^ in the inner monolayer of the vesicles by cyt c(red), and by the reoxidation of PDQ+ by Fd(ox) in the outer aqueous compartment. These reactions lead to the permanent accumulation of oxidized and reduced product proteins, i.e. cyt c(ox) in the inner compartment and Fd(red) in the outer compartment. The yields of such accumulation were 11%, based on the 3Chl quenched, and 1.4%, based on absorbed quanta, under the conditions used in the present study. This system mimics one of the key events in natural photosynthesis and results in an appreciable storage of electromagnetic energy in the reaction products.

Original languageEnglish (US)
Pages (from-to)113-122
Number of pages10
JournalPhotochemistry and Photobiology
Volume54
Issue number1
DOIs
StatePublished - Jan 1 1991

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Ferredoxins
Lipid bilayers
cytochromes
Lipid Bilayers
chlorophylls
compartments
Chlorophyll
Cytochromes c
lipids
electron transfer
Electrons
Unilamellar Liposomes
proteins
Genetic Recombination
Oxidation-Reduction
Diquat
membranes
Membranes
Electromagnetic Radiation
Proteins

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry
  • Physical and Theoretical Chemistry

Cite this

@article{2145509eab0440b6854b3294663a3e7c,
title = "CHLOROPHYLL PHOTOSENSITIZED ELECTRON TRANSFER REACTIONS IN LIPID BILAYER VESICLES: VECTORIAL ELECTRON TRANSFER ACROSS THE BILAYER FROM REDUCED CYTOCHROME c IN THE INNER COMPARTMENT TO OXIDIZED FERREDOXIN IN THE OUTER COMPARTMENT",
abstract = "A negatively charged large unilamellar vesicle system containing a membrane‐bound photo‐sensitizer (chlorophyll, Chi), a reduced redox protein [cytochrome c, cyt c(red)] in the inner aqueous compartment, an oxidized redox protein [ferredoxin, Fd(ox)] in the outer aqueous compartment, and propylene diquat (PDQ2+) as a mediator, was investigated using both flash and steady‐state photolysis techniques. The results demonstrate that the light‐generated triplet state of Chi (3Chl) was initially quenched by PDQ2+ at the outer membrane surface to form Chi cation radical (Chl+) and the reduced diquat (PDQ+). This was succeeded by a biphasic recombination between Chi+ and PDQ+. The slow phase of the recombination process, which represents reverse electron transfer between Chl+ and those PDQ+ molecules which escaped from the membrane surface, could be suppressed effectively both by the reduction of Chl^ in the inner monolayer of the vesicles by cyt c(red), and by the reoxidation of PDQ+ by Fd(ox) in the outer aqueous compartment. These reactions lead to the permanent accumulation of oxidized and reduced product proteins, i.e. cyt c(ox) in the inner compartment and Fd(red) in the outer compartment. The yields of such accumulation were 11{\%}, based on the 3Chl quenched, and 1.4{\%}, based on absorbed quanta, under the conditions used in the present study. This system mimics one of the key events in natural photosynthesis and results in an appreciable storage of electromagnetic energy in the reaction products.",
author = "Zhan-Gong Zhao and Gordon Tollin",
year = "1991",
month = "1",
day = "1",
doi = "10.1111/j.1751-1097.1991.tb01993.x",
language = "English (US)",
volume = "54",
pages = "113--122",
journal = "Photochemistry and Photobiology",
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T1 - CHLOROPHYLL PHOTOSENSITIZED ELECTRON TRANSFER REACTIONS IN LIPID BILAYER VESICLES

T2 - VECTORIAL ELECTRON TRANSFER ACROSS THE BILAYER FROM REDUCED CYTOCHROME c IN THE INNER COMPARTMENT TO OXIDIZED FERREDOXIN IN THE OUTER COMPARTMENT

AU - Zhao, Zhan-Gong

AU - Tollin, Gordon

PY - 1991/1/1

Y1 - 1991/1/1

N2 - A negatively charged large unilamellar vesicle system containing a membrane‐bound photo‐sensitizer (chlorophyll, Chi), a reduced redox protein [cytochrome c, cyt c(red)] in the inner aqueous compartment, an oxidized redox protein [ferredoxin, Fd(ox)] in the outer aqueous compartment, and propylene diquat (PDQ2+) as a mediator, was investigated using both flash and steady‐state photolysis techniques. The results demonstrate that the light‐generated triplet state of Chi (3Chl) was initially quenched by PDQ2+ at the outer membrane surface to form Chi cation radical (Chl+) and the reduced diquat (PDQ+). This was succeeded by a biphasic recombination between Chi+ and PDQ+. The slow phase of the recombination process, which represents reverse electron transfer between Chl+ and those PDQ+ molecules which escaped from the membrane surface, could be suppressed effectively both by the reduction of Chl^ in the inner monolayer of the vesicles by cyt c(red), and by the reoxidation of PDQ+ by Fd(ox) in the outer aqueous compartment. These reactions lead to the permanent accumulation of oxidized and reduced product proteins, i.e. cyt c(ox) in the inner compartment and Fd(red) in the outer compartment. The yields of such accumulation were 11%, based on the 3Chl quenched, and 1.4%, based on absorbed quanta, under the conditions used in the present study. This system mimics one of the key events in natural photosynthesis and results in an appreciable storage of electromagnetic energy in the reaction products.

AB - A negatively charged large unilamellar vesicle system containing a membrane‐bound photo‐sensitizer (chlorophyll, Chi), a reduced redox protein [cytochrome c, cyt c(red)] in the inner aqueous compartment, an oxidized redox protein [ferredoxin, Fd(ox)] in the outer aqueous compartment, and propylene diquat (PDQ2+) as a mediator, was investigated using both flash and steady‐state photolysis techniques. The results demonstrate that the light‐generated triplet state of Chi (3Chl) was initially quenched by PDQ2+ at the outer membrane surface to form Chi cation radical (Chl+) and the reduced diquat (PDQ+). This was succeeded by a biphasic recombination between Chi+ and PDQ+. The slow phase of the recombination process, which represents reverse electron transfer between Chl+ and those PDQ+ molecules which escaped from the membrane surface, could be suppressed effectively both by the reduction of Chl^ in the inner monolayer of the vesicles by cyt c(red), and by the reoxidation of PDQ+ by Fd(ox) in the outer aqueous compartment. These reactions lead to the permanent accumulation of oxidized and reduced product proteins, i.e. cyt c(ox) in the inner compartment and Fd(red) in the outer compartment. The yields of such accumulation were 11%, based on the 3Chl quenched, and 1.4%, based on absorbed quanta, under the conditions used in the present study. This system mimics one of the key events in natural photosynthesis and results in an appreciable storage of electromagnetic energy in the reaction products.

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