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  • 1
    Electronic Resource
    Electronic Resource
    Thermal denaturation of DNA: Interferometric depolarized light-scattering study (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 1473-1477 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210716
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  • 2
    Electronic Resource
    Electronic Resource
    Light-scattering spectroscopic study of polysaccharide protein conjugate (1982)
    New York : Wiley-Blackwell
    Biopolymers 21 (1982), S. 1503-1520 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By combining gel permeation chromatography (GPC) and light-scattering spectroscopy, including photon correlation and angular distribution of absolute scattered intensity, we were able to characterize immunologically active Haemophilus influenzae type b polysaccharide (HIB Ps) bovine serum albumin (BSA) conjugates in terms of equivalent hydrodynamic radius rh ∼ (6.2 ± 0.6) × 102 Å, apparent radius of gyration rg ∼ (5.4 ± 0.3) × 102 Å, apparent molecular weight Mw ∼ (3.5 ± 0.4) × 106 g/mol, and a second virial coefficient A2 ∼ (1.9 ± 0.3) × 10-4 cm3 mol/g2. We could study the effects of each of the processes in the conjugate formation according to the following procedure: BSA (dialysis, modification, fractionation) + HIB Ps → HIB Ps/BSA conjugate (conjugate formation, fractionation). Narrow distributions of HIB Ps BSA conjugate formation can be achieved using fractionated BSA.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360210804
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  • 3
    Electronic Resource
    Electronic Resource
    Size and shape parameter of the actin-binding protein profilin in solution: A depolarized and polarized dynamic light scattering study (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 219-222 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300123
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  • 4
    Electronic Resource
    Electronic Resource
    Internal dynamics of tRNAPhe studied by depolarized dynamic light scattering (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 975-983 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The collective internal dynamics of transfer RNAphe from brewer's yeast in solution was studied by depolarized dynamic light scattering (DDLS). Within the melting region of tRNA the depolarized spectra consist of two Lorentzian, where the narrow (slow) component describes the overall rotation of the macromolecule. The broad component is attributed to the collective reorientation of the bases within the biopolymer. At high temperature only this relaxation process is observed in the spectrum. The viscosity dependence of the collective internal relaxation process is described by the Stokes-Einstein-Debye equation for rotational diffusion. Estimates of the internal orientational pair correlation factor from the integral depolarized intensities of tRNAPhe solutions indicates that the observed dynamics correspond to the collective reorientation of approximately 5 bases. A comparison of the results presented with DDLS studies on the aggregation of the mononucleotide guanosine-5′-monophosphate confirms this result. For a further characterization of the relaxation process we studied the effect of hydrostatic pressure (1-1000 bar) on the depolarized spectra of tRNA. While other spectroscopic methods like nmr, fluorescence polarization anisotropy decay, or ESR give information about the very local motion of a single base within the DNA or RNA, this study shows that by DDLS one can characterize collective internal motions of macromolecules.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300912
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  • 5
    Electronic Resource
    Electronic Resource
    A polarized and depolarized dynamic light scattering study of the tRNAphe conformation in solution (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 93-105 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dynamics of tRNAphe from brewer's yeast in solution was studied over a broad concentration and temperature range by polarized and depolarized dynamic light scattering. It is shown that measurements of the depolarized Rayleigh spectrum with a high-resolution confocal Fabry-Perot interferometer provide very accurate values for the rotational diffusion coefficient of the biopolymer. The translational diffusion coefficient was determined by polarized photon correlation spectroscopy. A combination of both transport coefficients allows one to calculate the hydrodynamic size of tRNAphe using the Perrin equations for an biaxial ellipsoid. Within a temperature range from 9 to 45°C, the tRNAphe molecule adopts a nearly spherical shape. The dimensions are similar to the previously proposed U-shaped structure. In the melting region a second relaxation process was observed that is attributed to the collective reorientation of the bases. The concentration dependence of the rotational diffusion coefficient of tRNAphe in the concentration range of 2-75 mg/mL exhibits a slightly positive slope, in agreement with previous experimental findings and in contradiction to the theoretical predictions based on hydrodynamic interactions in solution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300111
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  • 6
    Electronic Resource
    Electronic Resource
    The molecular dimensions of G-actin in solution as studied by dynamic light scattering (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 1281-1287 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational and the translational diffusion coefficients of G-actin in solution have been obtained by polarized and depolarized dynamic light scattering, respectively. Modeling the shape of the molecule by a biaxial ellipsoid of revolution, the hydrodynamic dimensions were calculated from the Perrin equations. In completion to previous hydrodynamic measurements, a combination of both light scattering experiments provides direct information about the anisotropic form of G-actin in solution. The result indicates that the form of G-actin in solution is not significantly different from the overall structure in the solid state as obtained by x-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360301312
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  • 7
    Electronic Resource
    Electronic Resource
    Size, shape parameters, and Ca2+-induced conformational change of the gelsolin molecule: A dynamic light scattering study (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 427-435 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have investigated the size and shape of gelsolin, a calcium-dependent actin-binding protein, by means of combined photon correlation spectroscopy and depolarized dynamic light scattering. From the measured rotational and translational diffusion coefficients, a hydrodynamically equivalent ellipsoid of revolution with an axial ratio of 0.23 is obtained in the presence of EGTA. Such a distinctly elongated shape is suggested also by the depolarization ratio of 1.6 × 10-3. In the presence of Ca2+, when gelsolin has two Ca ions bound, a significant decrease in the translational diffusion coefficient and a smaller decrease in the rotational diffusion coefficient are observed. Both effects can be assigned to a change of shape from the elongated toward a more spherical form with an axial ratio of 0.37 and a hydrodynamic volume more than twice as large as in the absence of Ca2+. The apparent molecular mass as measured by static light scattering remains unchanged, indicating that the volume increase is not due to aggregation of gelsolin. The relatively large conformational changes observed upon binding of Ca2+, are probably related to an alteration of the surface charge of the molecule. As a result of these conformational changes, actin binding sites may become exposed and the molecule gains a high affinity for two actin molecules.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300320
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  • 8
    Electronic Resource
    Electronic Resource
    Intensity-fluctuation spectroscopy and tRNA conformation. II. Changes of size and shape of tRNA in the melting process (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2643-2662 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have measured the translational (DT) and rotational (DR) diffusion coefficients of bulk tRNA from baker's yeast during the thermal unfolding process by means of photon-correlation spectroscopy. It should be noted that our estimate of the rotational diffusion coefficient represented, for the first time, measurements on a small macromolecule in solution by the photoelectron time-of-arrival technique with a delay-time resolution of 1 nsec. The melting curves expressed in terms of δDT vs temperature were consistent with the literature data in revealing the melting steps and their dependence on NaCl concentration. Additionally, it was possible to prove the existence of an intermediate, more compact structure during the initial steps of the thermal unfolding process. We found that the temperature ranges over which this intermediate structure appears depend strongly on salt concentration. By utilizing both translational and rotational diffusion coefficients and Perrin's equations for ellipsoids of revolution, we have computed the values of the equivalent length and width of tRNA molecules in solution at four different temperatures for NaCl concentrations of 0.2, 0.5, and 1M. The approximate model of ellipsoids of revolution also permits us to obtain an estimate of the radius of gyration, which is in very good agreement with literature data measured by means of small-angle x-ray scattering. Furthermore, we have measured the shape and size changes of tRNA with varying NaCl concentrations at room temperatures (25°C). The molecule becomes smaller and more spherical when NaCl concentration increases. As a result of partial melting at 70°C, the macromolecule is surprisingly elongated with an approximate axial ratio of 8:1 and has dimensions of about 180/22Å. Such information on conformational changes by a simultaneous determination of rotational and translational diffusion coefficients illustrates the potential of this approach, not available by other methods.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171112
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  • 9
    Electronic Resource
    Electronic Resource
    Intensity fluctuation spectroscopy and transfer RNA conformation. III. Influence of NaCl concentration on the size and shape of the initially salt-free tRNA in solution (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2051-2072 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of sodium ion concentration in solution on the initially salt-free conformation of bulk tRNA from baker's yeast has been investigated by means of photon correlation spectroscopy. From the measured values of translational (DT) and rotational (DR) diffusion coefficients, the semiaxes of an ellipsoid of revolution, which are hydrodynamically equivalent to the tRNA molecule, were calculated for tRNA solutions in pure H2O as well as in 0.005, 0.1, 0.5M NaCl and 0.01M MgCl2 solutions at pH 4.2 and 7.5. These data, combined with our previous studies, suggested a model which describes the formation of an ordered tRNA structure due to increasing NaCl concentrations. Furthermore, we have obtained information concerning intermolecular interactions between tRNA molecules in solution. In low-salt or salt-free tRNA solutions, we detected in the linewidth distribution function an extra-fast component which can be attributed as possibly due to charge fluctuations related to the reaction of ionization of organic bases. In our light-scattering linewidth measurements, we do not see fluctuations of charged and uncharged states directly as concentration fluctuations. Rather, we postulate a modulation of long-range intermolecular electrostatic interactions between the tRNA molecules due to such charge fluctuations. It is this modulation which is related to the fast component of the time correlation function at finite concentrations. A quantitative theory is needed to provide a more definitive explanation of the dynamical behavior of tRNA in salt-free or low-salt solutions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180816
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  • 10
    Electronic Resource
    Electronic Resource
    Light scattering studies on long-range density fluctuations in a glass-forming polymer (1994)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 45 (1994), S. 137-142 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Static and dynamic light scattering measurements were performed on a glass-forming polymer, poly(methyl-p-tolylsiloxane) (PMpTS; Tg=-17°C), in a temperature range of 30°C to 120°C. It was found that long-range density fluctuations, so-called clusters, are observed in this polymer. They are characterized by “excess” angular-dependent isotropic scattered intensity and additional slow decay in the photon correlation function. These properties are generally observed in low molecular weight glass formers as well as in glass-forming polymers. In addition, we found that the clusters completely disappear above about 90°C. The kinetics of the cluster growth was also studied by temperature jump experiments. During the cluster formation process after the temperature jump, we measured the angular-dependent polarized scattered intensities, and the photon correlation function as a function of annealing time. We discuss the cluster growth kinetics based on these results, especially the time evolution of the correlation length ξOZ evaluated using the Ornstein-Zernike formula, the isotropic scattering intensity IOZ(0) at q=0, and the correlation time τcl of the cluster decay. Finally, we briefly discuss some properties of the equilibrated clusters, which are well reproducible.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1994.010450302
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