| | 1 | Author
| Maya Velitchkova, A. Ntoaneta Popova, Tzvetelina Markova | Requires cookie* | | | Title
| Effect of Membrane Fluidity on Photoinhibition of Isolated Thylakoids Membranes at Room and Low Temperature  | | | | Abstract
| The relationship betw een thylakoid membrane fluidity and the process of photoinhibition at room and low (4 °C) temperature was investigated. Two different membrane perturbing agents -cholesterol and benzylalcohol were applied to manipulate the fluidity of isolated pea thylakoids. The photochemical activity of photosystem I (PSI) and photosystem II (PSII), polarographically determ ined, were measured at high light intensity for different time of illumination at both temperatures. The exposure of cholesterol-and benzylalcohol-treated thylakoid membranes to high light intensities resulted in inhibition of both studied photo chemical activities, being more pronounced for PSII compared to PSI. Time dependencies of inhibition o f PSI and PSII electron transport rates for untreated and membranes with altered fluidity were determ ined at 20 °C and 4 °C. The effect is more pronounced for PSII activity during low-temperature photoinhibition. The data are discussed in terms of the determining role of physico-chemical properties of thylakoid membranes for the response o f photosyn thetic apparatus to light stress. | | | |
Reference
| Z. Naturforsch. 56c, 369—3 (2001); received January 3/February 1 2001 | | | |
Published
| 2001 | | | |
Keywords
| Membrane Fluidity, Photoinhibition, Thylakoid Membranes | | | |
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| default:Reihe_C/56/ZNC-2001-56c-0369.pdf | | | | Identifier
| ZNC-2001-56c-0369 | | | | Volume
| 56 | |
| 2 | Author
| G. K. Ulandaivelu An, D.0 H All | Requires cookie* | | | Title
| Ultrastructural Changes in in vitro Ageing Spinach Chloroplasts | | | | Abstract
| Ultrastructural changes in in vitro ageing spinach chloroplasts have been studied in detail. Prolonged storage caused swelling of the chloroplasts due to the increase in the thickness and spacing of the thylakoid membranes. The increase in the thickness of the membrane is partly ac companied by the release of lipids. Addition of crystalline bovine serum albumin was found to stabilize the membrane structures. Storage of the chloroplasts at 77 °K even though it resulted in complete breakage of the whole chloroplasts, maintained the thylakoid structures in a highly intact form. | | | |
Reference
| (Z. Naturforsch. 31c, 82 [1976]; received August 8 1975) | | | |
Published
| 1976 | | | |
Keywords
| Ultrastructure, Thylakoid Membrane, Ageing, Storage Conditions, Spinach | | | |
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| | | | | TEI-XML for
| default:Reihe_C/31/ZNC-1976-31c-0082.pdf | | | | Identifier
| ZNC-1976-31c-0082 | | | | Volume
| 31 | |
| 3 | Author
| Wilhelm Menke, Alfons Radunz, GeorgH. Schmid, Friederike Koenig, Rolf-Dieter Hirtz | Requires cookie* | | | Title
| Intermolecular Interactions of Polypeptides and Lipids in the Thylakoid Membrane | | | | Abstract
| Intermolecular interactions between chloroplast lipids and a polypeptide fraction from thylakoids were investigated by far ultraviolet circular dichroism. The polypeptide fraction was isolated from dodecyl sulfate-containing buffers. It exhibits an average molecular weight of 24 000. The circular dichroism of this polypeptide fraction measured as mean residue ellipticity is greater in the presence of sodium dodecyl sulfate than in the absence of this detergent. This effect is reversible. Addition of sulfoquinovosyl diglyceride to the dodecyl sulfate-free solution of the polypeptide also causes an increase of the circular dichroism. This increase was only observed in the pH-range between 6.9 and 7.4. The effect of dodecyl sulfate or sulfolipid on the circular dichroism is inter preted to indicate an increase of a-helix content. Monogalactosyl diglyceride, digalactosyl di glyceride and phosphatidyl glycerol gave no reaction. The attempt to obtain a conformational analysis of the polypeptide in the different states did not yield an entirely satisfactory result. Anti sera to sulfolipid inhibit photosynthetic electron transport of stroma-freed chloroplasts in the region of light reaction I. This inhibition is restricted to the same pH-range as the non-covalent binding of sulfolipid to the polypeptides. It appears that in the cell membrane-bound metabolic processes are regulated by this pH-dependence of the sulfolipid-polypetide interactions. | | | |
Reference
| (Z. Naturforsch. 31c, 436 [1976]; received April 30 1976) | | | |
Published
| 1976 | | | |
Keywords
| Interactions, Polypeptides, Lipids, Thylakoid Membrane, Photosynthesis | | | |
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| default:Reihe_C/31/ZNC-1976-31c-0436.pdf | | | | Identifier
| ZNC-1976-31c-0436 | | | | Volume
| 31 | |
| 4 | Author
| Alfons Radunz | Requires cookie* | | | Title
| Localization of the Tri-and Digalactosyl Diglyceride in the Thylakoid Membrane with Serological Methods | | | | Abstract
| Trigalactosyl diglyceride was isolated from leaves of Urtica dioica and characterized by thin layer chromatography, infrared spectroscopy and by its fatty acid composition. An antiserum to the trigalactolipid was obtained by immunization of rabbits. By means of inhibition experiments with oligosaccharides and mono-and digalactosyl glycerol it was demonstrated that the antibodies are directed towards the a-galactosyl-(1 -> 6) -a-galactosyl-(1 — ► 6) -/5-galactosyl-(1 -*■ 1) -glycerol con figuration of the trigalactosyl diglyceride. Monogalactosyl diglyceride and sulfoquinovosyl diglyce ride do not react with this antiserum. However, a cross reaction was observed with digalactosyl diglyceride. The presence of antibodies to tri-and digalactosyl diglyceride was demonstrated in antisera to different chloroplast preparations of Antirrhinum majus and Spinacia oleracea. The antiserum to the trigalactolipid agglutinates stroma-freed chloroplasts. Membrane fragments obtained by the ultra sonication were precipitated. The antiserum is exhausted by trigalactosyl di glyceride but not by digalactosyl diglyceride or digalactosyl glycerol. The antiserum treated with digalactosyl glycerol and digalactosyl diglyceride also agglutinated stroma-freed chloroplasts. 1 g stroma-freed chloroplasts binds 0.17 g antibodies to trigalactolipid. Membrane fragments bind more antibodies to trigalactolipids than stroma-freed chloroplasts. From the agglutination tests it follows that the antigenic determinants of the trigalactolipid and the digalactolipid are localized in the outer surface as well as in the surface directed towards the inside of the thylakoid membrane. | | | |
Reference
| (Z. Naturforsch. 31c, 589 [1976]; received July 19 1976) | | | |
Published
| 1976 | | | |
Keywords
| Trigalactosyl Diglyceride, Digalactosyl Diglyceride, Antibodies, Chloroplasts, Thylakoid Membrane | | | |
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| default:Reihe_C/31/ZNC-1976-31c-0589.pdf | | | | Identifier
| ZNC-1976-31c-0589 | | | | Volume
| 31 | |
| 7 | Author
| W. Bilger, U. Heber, U. Schreiber | Requires cookie* | | | Title
| Kinetic Relationship between Energy-Dependent Fluorescence Quenching, Light Scattering, Chlorophyll Luminescence and Proton Pumping in Intact Leaves | | | | Abstract
| A measuring system was designed for simultaneous recording of modulated chlorophyll fluorescence and light scattering changes. The kinetic relationship was investigated between light-induced changes in non-photochemical fluorescence quenching, as determined by the saturation pulse method, and in light scattering, as measured via the apparent absorbance change at 543 nm. Very similar, but not identical kinetics were observed, reflecting a close non-linear relationship between these two indicators of thylakoid membrane energization. Fluorescence was found more sensitive at low levels of energization, while scattering continued indicating further increases in energization when quenching already was saturated. A general relationship between quenching and scattering is demonstrated which holds irrespective of whether energization is varied during induction or via changes in light intensity or C02 concentration. In the light-off responses, only part of fluorescence quenching was found to relax with the same kinetics as scattering. It is suggested that at high levels of energization slowly reversible membrane changes may be induced which have the potential of non-photochemical quenching at a low level of energization, and which are not accompanied by scattering changes. Neither quenching nor scattering changes displayed kinetics sufficiently fast to be taken as a direct expression of internal thylakoid acidifica-tion in intact leaves. This conclusion is drawn from comparative measurements of proton-uptake, as reflected by C02-solubilization upon light-induced stroma alkalization, and of chlorophyll luminescence. Both, the initial C02-gulp and the pH-dependent luminescence rise were found to clearly precede the development of energy-dependent quenching. | | | |
Reference
| Z. Naturforsch. 43c, 877—887 (1988); received July 18 1988 | | | |
Published
| 1988 | | | |
Keywords
| Chlorophyll Fluorescence, Light Scattering, Chlorophyll Luminescence, Thylakoid Membrane, Proton Pumping | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0877.pdf | | | | Identifier
| ZNC-1988-43c-0877 | | | | Volume
| 43 | |
| 8 | Author
| Alfons Radunz, Renate Meier | Requires cookie* | | | Title
| Binding o f Antibodies onto the Thylakoid Membrane VII. Localization o f Coupling Factor o f Photophosphorylation in the Lamellar System o f Chloroplasts from Antirrhinum majus | | | | Abstract
| The maximal binding o f antibodies against the subunits o f the coupling factor o f photo phosphorylation onto the ultrasonic sediment and to stroma-freed chloroplasts o f Antirrhinum majus was determined. Different surfaces o f the thylakoid membrane are accessible to antibodies in both chloroplast preparations. Stroma-freed chloroplasts bind antibodies only at the outer sur face, which is directed towards the stroma in intact chloroplasts. In the ultrasonic sediment, which is the product of ultrasonication and centrifugation, as was demonstrated by electronmicroscopy, the major part o f the surface directed towards the inside o f the thylakoids is accessible. Both chloroplasts preparations are able to bind different amounts o f antibodies to the five sub units of the coupling factor. While antigenic determinants o f all five subunits are present on the surface directed to the outside, the «^-components seems to be lacking on the surface directed | | | |
Reference
| Z. Naturforsch. 37c, 236 (1982); received December 3 1981 | | | |
Published
| 1982 | | | |
Keywords
| Chloroplasts, Thylakoid Membrane, Subunits o f the Coupling Factor, Antibodies, Maximal Binding o f Antibodies | | | |
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| default:Reihe_C/37/ZNC-1982-37c-0236.pdf | | | | Identifier
| ZNC-1982-37c-0236 | | | | Volume
| 37 | |
| 9 | Author
| Anastasios Melis, C. Onrad, W. M. Ullineaux, JohnF. Allen | Requires cookie* | | | Title
| Acclimation of the Photosynthetic Apparatus to Photosystem I or Photosystem II Light: Evidence from Quantum Yield Measurements and Fluorescence Spectroscopy of Cyanobacterial Cells | | | | Abstract
| Cells of the cyanobacterium Synechococcus 6301 were grown under illumination whose spectral composition favoured absorption either by the phycobilisome (PBS) light-harvesting antenna of photosystem II (PS II) or by the chlorophyll (Chi) a light-harvesting antenna of photosystem I (PS I). Cells grown under PS I-light developed relatively high PS II/PS I and PBS/Chl ratios. Cells grown under PS II-light developed relatively low PS II/PS I and PBS/Chl ratios. Thus, the primary difference between cells in the two acclimation states appeared to be the relative concentration of PBS-PS II and PS I complexes in the thylakoid membrane. Measurements of the quantum yield of oxygen evolution suggested a higher efficiency of cellular photosynthesis upon the adjustment of photosystem stoichiometry to a specific light condition. The quantum yield of oxygen evolution was nevertheless lower under PBS than Chi excitation, suggesting quenching of excitation energy in the photochemical apparatus of PS II in Synechococcus 6301. This phenomenon was more pronounced in the PS II-light than in the PS I-light grown cells. Room temperature and 77 K fluorescence emission spectroscopy indicated that excess excitation energy in the PBS was not transferred to PS I, suggesting the operation of a non-radiative and non-photochemical decay of excitation energy at the PBS-PS II complex. This non-photochemical quenching was specific to conditions where excitation of PS II occurred in excess of its capacity for useful photochemistry. | | | |
Reference
| Z. Naturforsch. 44c, 109 (1989); received October 1 1988 | | | |
Published
| 1989 | | | |
Keywords
| Photosystem Stoichiometry, Thylakoid Membrane, Light-Harvesting, Excitation Energy Dis tribution, Oxygen Evolution | | | |
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| default:Reihe_C/44/ZNC-1989-44c-0109.pdf | | | | Identifier
| ZNC-1989-44c-0109 | | | | Volume
| 44 | |
| 10 | Author
| J. K. Ru K, K. B., Rd Ab>, A. R. Adunzc, K. Strzałka3, G. H. Schm | Requires cookie* | | | Title
| Antagonistic Effects of a-Tocopherol and a-Tocoquinone in the Regulation of Cyclic Electron Transport around Photosystem II | | | |
Reference
| Z. Naturforsch. 52c, 766—774 (1997); received August 22/ | | | |
Published
| 1997 | | | |
Keywords
| a-Tocopherol, a-Tocoquinone, Plastoquinone-A, Photosystem II, Cyclic Electron Transport, Oxygen Evolution, Thylakoid Membrane | | | |
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| default:Reihe_C/52/ZNC-1997-52c-0766.pdf | | | | Identifier
| ZNC-1997-52c-0766 | | | | Volume
| 52 | |
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