Mechanisms of photochemical energy conversion by chlorophyll: Progress report for period September 1, 1987-May 1, 1988

Technical Report · Sun May 01 00:00:00 EDT 1988

OSTI ID:5187228

Tollin, G

This project involves laser flash photolysis studies of the mechanism of electron transfer reactions involving chlorophyll triplet state and various electron donor and acceptor species occuring in lipid bilayer vesicles. Through the use of fluorescent probes, we have shown that the electrostatic binding of cytochrome /und c/ to positively-charged bilayer vesicles is accompanied by its intramembrane penetration. This supports our earlier studies which showed that binding led to quenching of chlorophyll triplets on both sides of the bilayer. That the bound cytochrome is mobile on the bilayer surface was demonstrated as the heme edge is not appreciably blocked from being reduced by reactants in the aqueous phase. In contrast to this, binding of plastocyanin to the bilayer does prevent electron transfer into the protein from the aqueous phase. Furthermore, the intrinsic reactivity of plastocyanin is increased by as much as six-fold upon binding to the membrane. We have also investigated the effects of electrostatic interactions on the kinetics, and the inside-outside asymmetry properties, of reactions between chlorophyll triplet and various small molecule acceptors in large unilamellar vesicles. Large effects were observed which could be interpreted in terms of charge-charge interactions between reactants, products and membrane components, as well as the existence of a spontaneous transmembrane electrical potential. 6 refs.

• Research Organization: Arizona Univ., Tucson (USA). Dept. of Biochemistry
• DOE Contract Number: FG02-86ER13631
• OSTI ID: 5187228
• Report Number(s): DOE/ER/13631-2; ON: DE88008763
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
59 BASIC BIOLOGICAL SCIENCES
CYTOCHROMES
BIOCHEMICAL REACTION KINETICS
PHOTOSYNTHETIC MEMBRANES
ELECTRON TRANSFER
PHYCOCYANIN
CHLOROPHYLL
DIAPHORASE
LASER SPECTROSCOPY
LIPOSOMES
PROGRESS REPORT
CARBOXYLIC ACIDS
CELL CONSTITUENTS
DOCUMENT TYPES
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
ISOALLOXAZINES
KINETICS
MEMBRANE PROTEINS
MEMBRANES
NUCLEOTIDE DEHYDROGENASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORGANOIDS
OXIDOREDUCTASES
PHYCOBILIPROTEINS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
REACTION KINETICS
SPECTROSCOPY
THYLAKOID MEMBRANE PROTEINS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
550200 - Biochemistry