scholarly journals Addition of lipid to the photosynthetic membrane: effects on membrane structure and energy transfer.

1981 ◽  
Vol 91 (1) ◽  
pp. 113-125 ◽  
Author(s):  
C O Siegel ◽  
A E Jordan ◽  
K R Miller
Keyword(s):  
Protein Complex ◽  
Freeze Fracture ◽  
Fluorescence Emission ◽  
Freezing And Thawing ◽  
Photosynthetic Membrane ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Light Reaction ◽  
Complex Ii ◽  
Chlorophyll Protein

We have carried out a series of experiments in which the lipid composition of the photosynthetic membrane has been altered by the addition of lipid from a defined source under experimental conditions. Liposomes prepared by sonication are mixed with purified photosynthetic membranes obtained from spinach chloroplasts and are taken through cycles of freezing and thawing. Several lines of evidence, including gel electrophoresis and freeze-fracture electron microscopy, indicate that an actual addition of lipid has taken place. Structural analysis by freeze-fracture shows that intramembrane particles are widely separated after the addition of large amounts of lipid, with one exception: large hexagonal lattices of particles appear in some regions of the membrane. These lattices are identical in appearance with lattices formed from a single purified component of the membrane known as chlorophyll-protein complex II. The suggestion that the presence of such lattices in lipid-enriched membranes reflects a profound rearrangement of photosynthetic structures has been confirmed by analysis of the fluorescence emission spectra of natural and lipid-enriched membranes. Specifically, lipid addition in each of the cases we have studied results in the apparent detachment of chlorophyll-protein complex II from photosynthetic reaction centers. It is concluded that specific arrangements of components in the photosynthetic membrane, necessary for the normal functioning of the membrane in the light reaction of photosynthesis, can be regulated to a large extent by the lipid content of the membrane.

scholarly journals The light-harvesting chlorpohyll-protein complex of photosystem II. Its location in the photosynthetic membrane.

1976 ◽  
Vol 71 (2) ◽  
pp. 624-638 ◽  
Author(s):  
K R Miller ◽  
G J Miller ◽  
K R McIntyre
Keyword(s):  
Photosystem Ii ◽  
Protein Complex ◽  
Light Harvesting ◽  
Fracture Face ◽  
Wild Type ◽  
Photosynthetic Membrane ◽  
Light Reaction ◽  
Particle Spacing ◽  
Inner Surface ◽  
Chlorophyll Protein

We have investigated the structure of the photosynthetic membrane in a mutant of barley known to lack a chlorophyll-binding protein. This protein is thought to channel excitation energy to photosystem II, and is known as the "light-harvesting chlorophyll-protein complex." Extensive stacking of thylakoids into grana occurs in both mutant and wild-type chloroplasts. Examination of membrane internal structure by freeze-fracturing indicates that only slight differences exist between the fracture faces of mutant and wild-type membranes. These differences are slight reductions in the size of particles visible on the EFs fracture face, and in the number of particles seen on the PFs fracture face. No differences can be detected between mutant and wild-type on the etched out surface of the membrane. In contrast, tetrameric particles visible on the etched inner surface of wild-type thylakoids are extremely difficult to recognize on similar surfaces of the mutant. These particles can be recognized on inner surfaces of the mutant membranes when they are organized into regular lattices, but these lattices show a much closer particle-to-particle spacing than similar lattices in wild-type membranes. Although several interpretations of these data are possible, these observations are consistent with the proposal that the light-harvesting chlorophyll-protein complex of photosystem II is bound to the tetramer (which is visible on the EFs face as a single particle) near the inner surface of the membrane. The large tetramer, which other studies have shown to span the thylakoid membrane, may represent an assembly of protein, lipid, and pigment comprising all the elements of the photosystem II reaction. A scheme is presented which illustrates one possibility for the light reaction across the photosynthetic membrane.

Studies on fluorescence of cellulosics

Holzforschung ◽  
2007 ◽  
Vol 61 (5) ◽  
pp. 504-508 ◽  
Author(s):  
Alain Castellan ◽  
Reinaldo Ruggiero ◽  
Elisabete Frollini ◽  
Ludmila A. Ramos ◽  
Christine Chirat
Keyword(s):  
Solid State ◽  
Microcrystalline Cellulose ◽  
Woody Plants ◽  
Average Molecular Weight ◽  
Homogeneous Medium ◽  
Fluorescence Emission ◽  
Excitation Wavelength ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Cotton Linters

Abstract Steady-state fluorescence emission spectra of various celluloses were measured at an excitation wavelength of 320 nm. Various spectra recorded in the solid state were compared: (1) ECF bleached papers made of hardwood, the anhydroglucose units of which were chemically modified at C1 and C6 or C2 and C3 positions with carboxylic groups; (2) microcrystalline cellulose; (3) cotton linters; and (4) delignified sisal fibers (mercerized or not). Fluorescence emission was quite independent of the carboxylic acid content and average molecular weight (determined by viscosimetry) of the cellulose polymers. Microcrystalline cellulose (Avicel), cotton linters, and mercerized delignified sisal cellulose were acetylated in homogeneous medium (DMAc/LiCl as solvent system) to obtain soluble polymers in dichloromethane for comparison of spectra recorded in the solid and liquid states. Fluorescence of cellulose acetates in solution (CH2Cl2) and in the solid state was compared under similar experimental conditions to non-esterified celluloses in the solid state. The importance of the solid state for fluorescence emission could be demonstrated. Fluorophores are present in minute amounts in the polymer and their favorable energy transfer for excitation in the solid state likely enhances fluorescence emission. Among numerous fluorophores, dityrosine appeared to be a good candidate for fluorescence because it displayed emission in the fluorescence range of cellulose. Dityrosine is an amino acid involved in the lignification of non-woody plants. Mercerized sisal impregnated with tyrosine in the presence of peroxidase and hydrogen peroxide did not show enhanced emission, in contrast to para-hydroxycinnamic acid (coumaric acid), which is also involved in the lignification process at least for non-woody plants. The origin of cellulose fluorescence remains uncertain and appears to have several origins. This study clearly underlines the importance of the solid state for enhancing fluorophore emission.

Extraction and stabilisation of the dimer of chlorophyll-protein complex II.

1979 ◽  
Vol 14 (1) ◽  
pp. 7-11 ◽  
Author(s):  
Roger G. Hiller ◽  
Theodora B.G. Pilger ◽  
Donna Campbell
Keyword(s):  
Protein Complex ◽  
Complex Ii ◽  
Chlorophyll Protein

scholarly journals Can Parietin Transfer Energy Radiatively to Photosynthetic Pigments?

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1741
Author(s):  
Beatriz Fernández-Marín ◽  
Unai Artetxe ◽  
José Becerril ◽  
Javier Martínez-Abaigar ◽  
Encarnación Núñez-Olivera ◽  
...  
Keyword(s):  
Photosynthetic Pigments ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Main Role ◽  
Transfer Energy ◽  
Experimental Conditions ◽  
Fluorescence Emission Spectra ◽  
Kinetic Assessment ◽  
Yellow Orange

The main role of lichen anthraquinones is in protection against biotic and abiotic stresses, such as UV radiation. These compounds are frequently deposited as crystals outside the fungal hyphae and most of them emit visible fluorescence when excited by UV. We wondered whether the conversion of UV into visible fluorescence might be photosynthetically used by the photobiont, thereby converting UV into useful energy. To address this question, thalli of Xanthoria parietina were used as a model system. In this species the anthraquinone parietin accumulates in the outer upper cortex, conferring the species its characteristic yellow-orange colouration. In ethanol, parietin absorbed strongly in the blue and UV-B and emitted fluorescence in the range 480–540 nm, which partially matches with the absorption spectra of photosynthetic pigments. In intact thalli, it was determined by confocal microscopy that fluorescence emission spectra shifted 90 nm towards longer wavelengths. Then, to study energy transfer from parietin, we compared the response to UV of untreated and parietin-free thalli (removed with acetone). A chlorophyll fluorescence kinetic assessment provided evidence of UV-induced electron transport, though independently of the presence of parietin. Thus, a role for anthraquinones in energy harvesting is not supported for X. parietina under presented experimental conditions.

Relationship between Changes in Ion Content of Leaves and Chlorophyll-Protein Composition in Cucumber under Cd and Pb Stress

1999 ◽  
Vol 54 (9-10) ◽  
pp. 746-753 ◽  
Author(s):  
Éva Sárvári ◽  
Ferenc Fodor ◽  
Edit Cseh ◽  
Anita Varga ◽  
Gyula Záray ◽  
...  
Keyword(s):  
Chlorophyll Content ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Light Harvesting ◽  
Fluorescence Emission ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Iron Deficient ◽  
Light Harvesting Complex Ii ◽  
Chlorophyll Protein

Hydroponically cultured cucumber plants supplied with 4 μᴍ Fe chelated either with EDTA or citrate and treated with Cd (10 μᴍ) and Pb (10, 50 μᴍ) from their one- or fourleaf stage were grown up to five-week-old age. The decrease in the chlorophyll content was the most pronounced in plants treated with Cd from a younger age, and in the case of Fecitrate. The chlorophyll a/b ratio of Cd stressed plants was also significantly lowered. In later treated plants the accumulation of chlorophyll was inhibited and the chlorophyll a/b ratio decreased only in the vigorously growing young leaves. Pb treatment had only a slight effect on both parameters. The changes in the chlorophyll-protein pattern of thylakoids were strongly related to their chlorophyll content but the response of each complex was different. Cd reduced the amount of chlorophyll containing complexes in the order of photosystem I > light-harvesting complex II > photosystem Il-core, while light-harvesting complex II appeared somewhat more sensitive than photosystem I in Pb treated plants. In accordance, a decline or blue shift of the long wavelength fluorescence emission band of chloroplasts was observed referring to disturbances also in photosystem I antenna assembly. The accumulation of chlorophyll and chlorophyll-proteins did not show close relationship to the heavy metal content of leaves which was the highest in the first of the intensively expanding leaves in the time of the treatment. The extraordinary sensitivity of photosystem I, and the relative stability of photosystem II under Cd treatment were similar to the case found in iron deficient plants. However, the pattern of chlorophyll content of leaf storeys of Cd treated plants rather followed the changes in their Mn content

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