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1Author    W. CariusRequires cookie*
 Title    Streulichtmessungen an ebenen Lipidmembranen. Modulation des Streulichts durch eine elektrische Wechselspannung an der Membran Modulation of Light Scattering by an Electric Voltage at Planar Lipid Membranes  
 Abstract    Light scattered at a planar lipid membrane is modulated by an electric a. c. voltage across the membrane. This effect is studied by a schlieren optic method. It shows a large contribution from the bilayer/torus border. From the inner part of the membrane no modulation of scattered light was detectable. Membranes were made from egg lecithin + cholesterol/decane in 0.1 n KC1 aqueous solution. 
  Reference    Z. Naturforsch. 33c, 174 (1978); received March 6 1978 
  Published    1978 
  Keywords    Lipid Bilayer, Light Scattering, Voltage Dependent, Torus, Lenses 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0174.pdf 
 Identifier    ZNC-1978-33c-0174 
 Volume    33 
2Author    C. Hristof Klugham, Er, Ulrich SchreiberRequires cookie*
 Title    Analysis of Light-Induced Absorbance Changes in the Near-Infrared Spectral Region I. Characterization of Various Components in Isolated Chloroplasts  
 Abstract    Light-induced absorbance changes in the near-infrared (N IR) spectral region (7 0 0 -9 5 0 nm) are analyzed in isolated spinach chloroplasts using pulsed light-emitting diodes as modulated measuring light sources. With chloroplasts under coupled conditions the light-induced signal is dominated by a relatively slow scattering change displaying a flat difference spectrum. More specific changes can be distinguished by faster induction and relaxation kinetics and in the presence o f valinomycin/nigericin which prevents scattering changes. Besides the dominant P700 change, with a narrow bleaching band around 703 nm and a broad absorbance increase between 750 and 850 nm (peak at 815 nm) the following absorbance changes were identified in the NIR: 1) An absorbance increase caused by plastocyanin (PC) oxidation, with a relatively flat spectrum. 2) An absorbance decrease gaining amplitude towards longer wavelengths, which reflects reduction o f a low potential acceptor o f PS I different from ferredoxin. 3) A field indicating absorbance decrease peaking around 730 nm, the properties o f which correspond to those o f P 515. 4) An uncoupler insensitive absorbance decrease stimulated by dark adaptation and anaero­ bic conditions, the difference spectrum o f which resembles that o f ferredoxin reduction. The relative contributions o f P700 and PC to the overall oxidized-reduced difference spec­ trum are determined by redox titration. At 706 nm, 815 nm and 950 nm the P 700/PC is -119/ 19, 67/37 and 31/69, respectively. From these ratios and the molar extinction coefficients a molar P 700/PC stoichiometry o f 1 /3 is determined. 
  Reference    Z. Naturforsch. 46c, 233 (1991); received November 19 1990/January 2 1991 
  Published    1991 
  Keywords    Plastocyanin, Membrane Potential, Ferredoxin, Light Scattering, Photosynthesis 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0233.pdf 
 Identifier    ZNC-1991-46c-0233 
 Volume    46 
3Author    Bronislaw Grzegorzewski, Volodymyr RudeichukRequires cookie*
 Title    Light Scattering in the Eye Lens Near the Spinodal  
 Abstract    Scattered light intensities measurements of the nuclear part of adult bovine lenses are reported. In the investigated samples the existence o f a binary liquid phase separation from a metastable state is demonstrated by the phenomenon of hysteresis. Fluctuations near spino­ dal are studied by means of a tentative theoretical approach. Accordingly the scattered light intensities were analyzed reduced by the intensity obtained for the stable state of the system. Fluctuations in the stable state are ascribed to protein aggregates and are analyzed by means of random density fluctuation theory. To evaluate the correlation length of the fluctuations near spinodal the Ornstein-Zernike theory is adopted. Temperature dependence of the corre­ lation length | of the fluctuations near spinodal can be described by equation for critical / t ~ T s\ ~ v fluctuations = ^ ' ^or invest*gated lenses the exponent v varies from 0.65 to 0.74 and the parameter S;0 varies from 1.6 nm to 3.6 nm. The spinodal temperature Ts for the investigated samples is evaluated. 
  Reference    Z. Naturforsch. 54c, 985—9 (1999); received May 17/May 24 1999 
  Published    1999 
  Keywords    Light Scattering, Eye Lens, Phase Separation, Aggregates 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0985.pdf 
 Identifier    ZNC-1999-54c-0985 
 Volume    54 
4Author    D. Lindenau, U. Hagen, W. SchnabelRequires cookie*
 Title    D etachm ent o f Segm ents from D N A D ouble Strands as D etected by Tim e R esolved Rayleigh Light Scattering  
 Abstract    Calf thymus DNA was irradiated in oxygen saturated 0.01 N NaCl solution with 2 /us pulses of 15 MeV electrons. By monitoring the decrease of light scattering intensity after the pulse, two modes of decrease were detected: The fast decrease (n /2 ä s 0.8 ms) is ascribed to the separation of DNA fragments produced by double strand breaks at posi­ tions directly opposite to each other. The slow decrease (r»/i ~ 8 s) is attributed to the detachment of segments generated by single strand breaks at sites on the alternate strands being separated by about 10 nucleotide units. 
  Reference    (Z. Naturforsch. 31c, 484 [1976]; received March 17/April 7 1976) 
  Published    1976 
  Keywords    DNA, High-Energy Radiation, Light Scattering, Detachment of Segments 
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 TEI-XML for    default:Reihe_C/31/ZNC-1976-31c-0484_n.pdf 
 Identifier    ZNC-1976-31c-0484_n 
 Volume    31 
5Author    W. Bilger, U. Heber, U. SchreiberRequires 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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 TEI-XML for    default:Reihe_C/43/ZNC-1988-43c-0877.pdf 
 Identifier    ZNC-1988-43c-0877 
 Volume    43 
6Author    K.-J Deeg, L. Katsikas, W. SchnabelRequires cookie*
 Title    High Energy Radiation-Induced Crosslinking of Histone Octamer Complexes  
 Abstract    Calf thymus histone octamer com plexes were irradiated in the native state in N 20 -satu rated dilute aqueous solution (0.5 g/1, pH 9, [N aC 104] = 1 — 4 m ol/1) with 50 or 100 ns pulses o f 16 MeV electrons or 60 Co-y-rays. Tim e resolved light scattering m easurem ents and optical ab­ sorption measurements yielded the following: the octamers underwent a volum e contraction due to intra-complex-crosslinking induced by the attack o f OH-radicals. Crosslinking proceeded to a certain extent via 2 ,2 '-biphenol coupling as inferred from product analyses. 
  Reference    Z. Naturforsch. 39c, 1075—1078 (1984); received June 14/August 8 1984 
  Published    1984 
  Keywords    Histone Octamers, High Energy Radiation, Light Scattering, Intra-C om plex-C rosslinking, Dityrosyl Links 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-1075.pdf 
 Identifier    ZNC-1984-39c-1075 
 Volume    39 
7Author    G. Ertraud Ribitsch, Rita De Clercq, Altraud Folkhard, Z. Peter, Ip, E. R3, Josef Schurz3, JuliusC. Lauw AertcRequires cookie*
 Title    Small-Angle X-Ray and Light Scattering Studies on the Influence of M g2+ Ions on the Structure of the RNA from Bacteriophage M S 2  
 Abstract    The influence o f M g2+ ions on the secondary and tertiary structure o f the RNA from bacteriophage MS2 was investigated by sm all-angle X-ray scattering and light scattering and by sedimentation experiments. The analysis o f the outer part o f the X-ray scattering curve obtained at low temperature in the absence o f Mg2+ yielded a cross-section radius o f gyration o f 0.88 nm and a mass per unit length o f 1720 g m ol-1 nn T 1. Very similar values for these parameters, which refer to the secondary structure o f the RNA m olecule, were also derived from the X-ray scattering curves obtained in the presence o f different am ounts o f Mg2+ (0.07 to 1 ions per nucleotide). On the contrary, the inner part o f the X-ray scattering curves turned out to be highly dependent on the Mg2 + concen­ tration: the cross-section radius o f gyration and the mass per unit length, which were determined from the scattering curves at small angles as parameters related to the tertiary structure o f the RNA, amounted to 3.11 nm and 4000 g m ol-1 n m -1, respectively, in the absence o f Mg2+ and in­ creased significantly upon raising the concentration o f M g2+. The increase o f these structural parameters was found to be accom panied by a decrease o f the overall radius o f gyration (as revealed indirectly by X-ray scattering and directly by light scattering m easurem ents) and by an increase o f the sedim entation coefficient. The results from the investigations o f the RNA at low temperature clearly establish the existence o f double-stranded structures dow n to very low M g2+ concentrations as well as the occurrence o f Mg2+ induced changes o f the tertiary structure. In the absence o f Mg2+ the RNA m olecule appears to be a rodlike particle o f about 300 nm length with a lateral diameter o f about 9 to 11 nm. Upon addition o f increasing am ounts o f M g2* this extended structure tightens, eventually forming a coil-like particle. Previous X-ray scattering experiments with MS 2 RNA at ionic strength 0.1 (Zipper, Folkhard and Clauwaert, FEBS Lett. 56, 2 8 3 -2 8 7 (1975)) have already established the axial dim ensions o f such coil-like particles to be about 63, 31 and 14 nm. The results from supplementary X-ray scattering experim ents performed at higher temperatures in the absence or presence o f Mg2+ clearly reflect the loss o f secondary structure due to m elting o f the RNA. This loss is, however, less pronounced at higher concentrations o f Mg2+. 
  Reference    Z. Naturforsch. 40c, 234 (1985); received August 20/D ecem b er 14 1984 
  Published    1985 
  Keywords    RNA, Interaction with M g2+, Small-Angle X -R ay Scattering, Light Scattering, Structural Changes 
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 TEI-XML for    default:Reihe_C/40/ZNC-1985-40c-0234.pdf 
 Identifier    ZNC-1985-40c-0234 
 Volume    40 
8Author    Dieter Vogel, GuyD. De, M. Arcillac, Leon Hirth, Eva Gregori, Rainer JaenickeRequires cookie*
 Title    Size Distribution in the Higher Stages of Polymerization of the A-Protein of Tobacco Mosaic Virus ( vulgare)  
 Abstract    The composition of the A-protein of tobacco mosaic virus (TMV) has been investigated by se­ dimentation velocity, light-scattering, spectroscopic methods, and thermodynamic calculations, at concentrations from 5 to 20 mg/ml, at temperatures from 7 to 26 °C , at various pH and buffer conditions. Above distinct critical concentrations and temperatures aggregates are formed which sediment near 8S, while the concentration of the smaller aggregates that sediment in the trailing boundary, near 4S, remains approximately constant. We identify the 4S protein with two-lajer aggregates (Durham and Klug, J. Mol. Biol., 1972), with weight average molecular weight (M w) near 5 subunits, at the lower limit of polymerization. The 8S aggregates are best described by a series of three-layer aggregates, starting with a heptamer (Caspar, Adv. Protein Chem., 1963), but attaining Mw corresponding to at least 12 subunits, at the upper limit. The 4 S /8 S equilibrium is not significantly changed by a change in pH, nor by the coexistence of higher aggregates (20 — 30 S) with residual "A-protein". Three-layer aggregates are more stable than two-layer aggregates, but significantly less stable than would be expected with strictly equivalent bonding; the third lay­ er in the 8 S protein disturbs the pairing between the two layers in the 4S protein, and the intersub­ unit interaction near tryptophan 52 seems to be involved. From the structure, 8S protein should tend to polymerize easier to helices than to disks, in accordance with earlier suggestions (Vogel et al., Eur. J. Biochem., 1977), and corroborated by studies on TMV-mutants. 
  Reference    Z. Naturforsch. 34c, 782—792 (1979); received May 21 1979 
  Published    1979 
  Keywords    TMV-A-Protein, Sedimentation Velocity, Light-Scattering, Two-and Three-Layer Aggregates, Size Distribution 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0782.pdf 
 Identifier    ZNC-1979-34c-0782 
 Volume    34