High Precision Measurements of the Permittivity of Water in the Microwave Range

Steinhoff, Heinz‐Jürgen; Redhardt, Albrecht; Lieutenant, K.; Chrost, W.; Hess, Guenter; Schlitter, Jürgen; Neumann, Helmut

doi:10.1515/zna-1990-0515

Cited by 11 publications

(14 citation statements)

References 15 publications

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“…Quite recently, ESR spin Iabetling has been proposed as rewarding tool in probing internal motions of proteins at low hydration [18][19][20][21][22][23][24]. A spin label covalently bound to a protein can be regarded as an artificial amino acid side chain [23].…”

Section: Introductionmentioning

confidence: 99%

“…A spin label covalently bound to a protein can be regarded as an artificial amino acid side chain [23]. Its ESR spectrum reflects the motion of the protein or some residual motion of the label with respect to the whole macromolecule.…”

Section: Introductionmentioning

confidence: 99%

“…At low hydration, however, the protein is immobilized by the scarcity of water. The rotational diffusion of the whole molecule is prevented and it is thus possible to investigate the residual motion of the label, which becomes a reporter of the protein intemal dynamics [23].…”

Section: Introductionmentioning

confidence: 99%

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Hydration and protein dynamics: an ESR and ST-ESR spin labelling study of human serum albumin

Marzola

Cannistraro

1992

Appl. Magn. Reson.

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Human serum albumin has been studied at low hydration level by the ESR spin labelling technique, under the assumption that a covalently bound spin-label is a reporter of the protein internal dynamics. At room temperature, the presence of a double component signal allowed us to monitor the influence of increasing hydration level on internal protein dynamics as well as on the superficial water dynamics. The ESR results have shown that the first 20 g of water per 100 g of protein activate the internal protein dynamics and that superficial water dynamics starts at higher hydration values. ESR expe¡ at low temperature have shown that at --l£176 ~ T~ -80~ the label experiences an increasing environmental polarity with increasing temperature in the samples with hydration values higher than about 20 g of water per 100 g of protein.The results are discussed in connection with both conformational substates of the protein and hydration water dynamics.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydration and protein dynamics: an ESR and ST-ESR spin labelling study of human serum albumin

Marzola

Cannistraro

1992

Appl. Magn. Reson.

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“…2). W-band EPR spectra were measured at 120 K. In the temperature regime below 200 K the reorientational correlation time of an otherwise unrestricted spin label side chain exceeds 100 ns [32], i.e., the nitroxide may be considered as immobilized on the EPR time scale. Librational motion of small amplitude still prevails and may lead to small deviations of the measured tensor values from their rigid limit values due to partial motional averaging.…”

Section: Resultsmentioning

confidence: 99%

“…Librational motion of small amplitude still prevails and may lead to small deviations of the measured tensor values from their rigid limit values due to partial motional averaging. However, this effect is small (e.g., less than 2% for A,Z at 200 K [32]) and is further minimized by decreasing the temperature for data collection to 120 K.…”

Section: Resultsmentioning

confidence: 99%

High-field EPR-detected shifts of magnetic tensor components of spin label side chains reveal protein conformational changes: The proton entrance channel of bacteriorhodopsin

et al. 2001

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Continuous-wave high-field electron paramagnetic resonance (95 GHz, 3.4 T) is performed on a spin label side chain located at residue position 171 in the proton entrance channel of bacteriorhodopsin. The conformational differences of three bacteriorhodopsin mutants, the single mutant F171C, the double mutant D96G/FI71C, and the triple mutant D96G/F1 71C/F2 19L, are reflected in different gg and A_ tensor component shifts of the nitroxide side chain. The most polar microenvironment is found in the single mutant, whereas the open proton entrance channel reported for the triple mutant allows a reorientation of the nitroxide group towards a microenvironment of lower polarity and/or reduced hydrogen bonding. The experimental data of the double mutant are explained by a lightindependent equilibrium of two nitroxide orientations with different polarities of the local microenvironment. Upon illumination the spectrum of the single mutant reveals gg and A component shifts which resemble those determined for the triple mutant in the dark. This result provides strong evidence for a light-induced opening of the proton entrance channel of the single mutant similar to that found in the unilluminated triple mutant, in agreement with electron diffraction data.

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Dielectric relaxation of aqueous electrolyte solutions. I. Solvent relaxation of 1:2, 2:1, and 2:2 electrolyte solutions

Barthel¹,

Hetzenauer²,

Buchner³

1992

Ber Bunsenges Phys Chem

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Complex permittivity measurements on aqueous solutions of CdCl2, CuCl2, MgSO4, CdSO4, Na2SO4, Cd(ClO4)2, and MgCl2 in the frequency range from 0.9 to 90 GHz are reported. The data analysis reveals the superposition of 2 Debye dispersion steps for the solvent thus supporting multi‐step relaxation mechanisms discussed for water in the literature. An additional low frequency process is found for CdCl2, CuCl2, MgSO4, CdSO4, and Na2SO4 solutions due to solute relaxation, but not for Cd(ClO4)2 and MgCl2 solutions. – The decrease of the static solvent permittivity at increasing electrolyte concentrations is interpreted in terms of irrotational bonding and kinetic depolarization and is used to determine effective solvation numbers. The dependence of the main (low frequency) relaxation time of water on electrolyte concentration is explained with the help of the reorientation and residence times of water in the hydration spheres of ions and in the bulk. The high frequency relaxation time is approximately concentration independent, whereas the dispersion amplitude of the process increases with electrolyte concentration.

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High Precision Measurements of the Permittivity of Water in the Microwave Range

Cited by 11 publications

References 15 publications

Hydration and protein dynamics: an ESR and ST-ESR spin labelling study of human serum albumin

Hydration and protein dynamics: an ESR and ST-ESR spin labelling study of human serum albumin

High-field EPR-detected shifts of magnetic tensor components of spin label side chains reveal protein conformational changes: The proton entrance channel of bacteriorhodopsin

Dielectric relaxation of aqueous electrolyte solutions. I. Solvent relaxation of 1:2, 2:1, and 2:2 electrolyte solutions

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