Biomaterial Database

Light emission originating from photosystem II radical pair recombination is sensitive to zeaxanthin related non-photochemical quenching (NPQ). 2006

Heiko Wagner, and Matthias Gilbert, and Reimund Goss, and Christian Wilhelm

Universität Leipzig, Biologie I/Abteilung Pflanzenphysiologie, Johannisallee 23, 04103 Leipzig, Germany.

We have used chlorophyll fluorescence, delayed luminescence and thermoluminescence measurements to study the influence of an artificial DeltapH in the presence or absence of zeaxanthin on photosystem II reactions. Energization of the pea thylakoid membranes induced non-photochemical fluorescence quenching and an increase in the overall luminescence emission of PSII during delayed luminescence and thermoluminescence measurements. This DeltapH-induced overall luminescence increase was caused by a strongly enhanced delayed luminescence in the seconds range before sample heating. In the subsequent thermoluminescence measurements the intensity of the B-band decreased after one and increased after two or more single turnover flashes. We propose that strong membrane energization shifted the redox potential of photosystem II radical pairs to more negative values causing the high delayed luminescence. The zeaxanthin-dependent non-photochemical fluorescence quenching component, however, did not alter thermoluminescence B-bands but decreased the delayed luminescence intensity by 30%. To our knowledge this is the first report that the radiative radical pair recombination, exhibited as delayed luminescence but not thermoluminescence emission, is sensitive to the antenna located zeaxanthin related non-photochemical fluorescence quenching. Our data can be interpreted within the frame of the exciton/radical pair equilibrium model that describes photosystem II as a shallow trap and incorporates the transfer of energy from the re-excitated reaction centre to the antenna of photosystem II.

UI	MeSH Term	Description	Entries
D002734	Chlorophyll	Porphyrin derivatives containing magnesium that act to convert light energy in photosynthetic organisms.	Phyllobilins,Chlorophyll 740
D005609	Free Radicals	Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. Free radicals include reactive oxygen and nitrogen species (RONS). They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.	Free Radical
D013696	Temperature	The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.	Temperatures
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D045332	Photosystem II Protein Complex	A large multisubunit protein complex found in the THYLAKOID MEMBRANE. It uses light energy derived from LIGHT-HARVESTING PROTEIN COMPLEXES to catalyze the splitting of WATER into DIOXYGEN and of reducing equivalents of HYDROGEN.	Chloroplast Reaction Center Protein D1,D1 Photosystem II Protein, Plant,Light-Induced D1 Protein, Photosystem II,Oxygen Evolving Enzyme,PRCP II D2 Protein,Photosystem II,Photosystem II Reaction Center,Photosystem II Reaction Center Complex D1 Protein,Photosystem II Reaction Center Complex D2 Protein,RCII-D1 Protein,Water Oxidase,Water-Splitting Enzyme of Photosynthesis,Enzyme, Oxygen Evolving,Evolving Enzyme, Oxygen,Light Induced D1 Protein, Photosystem II,Oxidase, Water,Photosynthesis Water-Splitting Enzyme,Water Splitting Enzyme of Photosynthesis
D049449	Luminescence	Emission of LIGHT when ELECTRONS return to the electronic ground state from an excited state and lose the energy as PHOTONS. It is sometimes called cool light in contrast to INCANDESCENCE. LUMINESCENT MEASUREMENTS take advantage of this type of light emitted from LUMINESCENT AGENTS.	Luminescence, Physical,Chemiluminescence,Chemiluminescence, Physical,Physical Chemiluminescence,Physical Luminescence
D018515	Plant Leaves	Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)	Plant Leaf,Leaf, Plant,Leave, Plant,Leaves, Plant,Plant Leave
D024341	Xanthophylls	Oxygenated forms of carotenoids. They are usually derived from alpha and beta carotene.	Xanthophyll Carotenoids,Carotenoids, Xanthophyll
D031541	Fluorescence Resonance Energy Transfer	A type of FLUORESCENCE SPECTROSCOPY using two FLUORESCENT DYES with overlapping emission and absorption spectra, which is used to indicate proximity of labeled molecules. This technique is useful for studying interactions of molecules and PROTEIN FOLDING.	Forster Resonance Energy Transfer
D065146	Zeaxanthins	Carotenoids found in fruits and vegetables. Zeaxanthin accumulates in the MACULA LUTEA.	3R,3'R-Zeaxanthin,Beta-Carotene-3,3'-Diol,Zeaxanthin,3R,3'R Zeaxanthin,Beta Carotene 3,3' Diol