Dielectric dispersion and dipole moment of myoglobin in water

South, G. P.; Grant, E H

doi:10.1098/rspa.1972.0083

Cited by 86 publications

(18 citation statements)

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“…Consider now the significance of relaxation peaks in TSC of hydrated proteins. Among the polarization modes are (1) polarization of the protein molecule or parts of it, due to dipolar interactions with the applied field, an effect observed for instance with myoglobin (South & Grant, 1972), apatites (Hitmi et al 1986) and collagen (Lamure et al 1985) and (2) polarizations due to molecules of water surrounding the protein as shown by Jacobson (1955) with a possible distinction between molecules of water having different degrees of binding. The comparative TSC study of samples with different levels of hydration should allow discrimination between both polarization -100…”

Section: Thermally Stinudated Currents Measurementsmentioning

confidence: 95%

Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents

Lamure

Pommert

Klaebe

et al. 1988

Journal of Dairy Research

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Samples of caseins having differentCa contents as used in cheese processing were analysed by techniques using differential scanning calorimetry and thermally stimulated currents (TSC) before and after treatment with Na polyphosphate, a food additive used in the manufacture of processed cheese. These techniques revealed structural changes induced by the salt, and the different types of water molecules associated with the protein are evident. This characterization is in agreement with results obtained by other techniques, particularly X-ray diffraction of proteins. Transmission electron microscopy of the same samples confirmed that the changes observed by TSC were associated with an unravelling of the protein.Polyphosphates have been used for a long time in cheese processing but their exact role is not yet fully understood (Shimp, 1985). For instance, it is not known why the amount of polyphosphates used (from 1 to a few percent) depends on the Ca content of the protein, or how the water-binding ability of the protein is changed after reaction with polyphosphates. Although X-ray studies of crystallized proteins (Blake et al. 1983) revealed that water participates in crystal packing it is not yet known, whether or not such organization exists in lyophilized protein samples similar to those used in cheese processing. Nor is it known what changes result from the addition of polyphosphates. In an attempt to obtain detailed information about the action of added polyphosphates in cheese processing, we have investigated, by differential scanning calorimetry (DSC) and thermally stimulated currents (TSC), samples of caseins before and after their treatment with polyphosphates. MATERIAL AND METHODSSamples of Na caseinate (casein I) and Ca caseinate (casein II) were obtained by spray drying the aqueous solution resulting from neutralizing and precipitating milk curd with NaOH and Ca(0H) 2 respectively. Final pH values were 6-8 for casein I and 6-6 for casein II. Casein I contained 4-7% H 2 O, 1-81% P and 0-026% Ca and casein II 9-9% H 2 O, 1-79% P and 3-44% Ca, expressed as weight percent.Na tripolyphosphate was obtained from Sigma Chemical Co. Reactions of

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Section: Thermally Stinudated Currents Measurementsmentioning

confidence: 95%

Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents

Lamure

Pommert

Klaebe

et al. 1988

Journal of Dairy Research

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“…This comparative lack of asymmetry means that the dielectric dispersion due to the myoglobin molecule should be able to be represented to a good approximation by a single relaxation time, ie, by the Debye dispersion relationship. Such was shown by South and Grant [1972], who made extensive measurements of permittivity and conductivity of myoglobin solution in the frequency range 0.2-10 MHz, at seven concentrations and over a wide range of temperature, pH, and ionic strength. In addition to characterizing the main myoglobin dispersion, this work also established the existence of an additional small Debye dispersion at frequencies a little higher than 10 MHz.…”

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confidence: 91%

Dielectric behavior of water in biological solutions: Studies on myoglobin, human low‐density lipoprotein, and polyvinylpyrrolidone

Grant

McClean

Nightingale

et al. 1986

Bioelectromagnetics

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The dielectric behavior of the aqueous solutions of three widely differing macromolecules has been investigated: myoglobin, polyvinylpyrrolidone (PVP), and human serum low-density lipoprotein (LDL). It was not possible to interpret unambiguously the dielectric properties of the PVP solution in terms of water structure. The best interpretation of the dielectric data on the myoglobin and LDL solutions was that, in both cases, the macromolecule attracts a layer of water of hydration one or two water molecules in width. For LDL, this corresponds to a hydration factor of only 0.05 g/g, whereas for myoglobin the figure is nearer 0.6 g/g. With myoglobin, part of the water of hydration exhibits its dispersion at frequencies of a few GHz, and the rest disperses at lower frequencies, perhaps as low as 10-12 MHz. The approximate constancy of the width of the hydration shell for two molecules as dissimilar in size as LDL and myoglobin confirms that the proportion of water existing as water of hydration in a biological solution depends critically on the size of the macromolecules as well as on their concentration.

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“…The description of the polar response in terms of the molecular charge distribution is more accurate for these solutes [7]. Given the length-scale of the external field variation in a typical dielectric or light-absorption experiment, the overall charge and the dipole moment are the two main multipoles to consider [8].…”

Section: Introductionmentioning

confidence: 99%

On the theory of dielectric spectroscopy of protein solutions

Matyushov¹

2012

J. Phys.: Condens. Matter

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We present a theory of the dielectric response of solutions containing large solutes, of the nanometer size, in a molecular solvent. It combines the molecular dipole moment of the solute with the polarization of a large subensemble of solvent molecules at the solute-solvent interface. The goal of the theory is two-fold: (i) to formulate the problem of the dielectric response avoiding the reliance on the cavity-field susceptibility of dielectric theories and (ii) to separate the non-additive polarization of the interface, jointly produced by the external field of the laboratory experiment and the solute, from specific solute-solvent interactions contributing to the dielectric signal. The theory is applied to experimentally reported frequency-dependent dielectric spectra of lysozyme in solution. The analysis of the data in the broad range of frequencies up to 700 GHz shows that the cavity-field susceptibility, critical for the theory formulation, is consistent with the prediction of Maxwell's electrostatics in the frequency range of 10-200 GHz, but deviates from it outside this range. In particular, it becomes much smaller than the Maxwell result, and shifts to negative values, at small frequencies. The latter observation implies a dia-electric response, or negative dielectrophoresis, of hydrated lysozyme. It also implies that the effective protein dipole recorded by dielectric spectroscopy is much smaller than the value calculated from the protein's charge distribution. We suggest an empirical equation that describes both the increment of the static dielectric constant and the decrement of the Debye water peak with increasing protein concentration. It gives fair agreement with broad-band dispersion and loss spectra of protein solutions, but misses the δ-dispersion region.

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Dielectric dispersion and dipole moment of myoglobin in water

Cited by 86 publications

References 2 publications

Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents

Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents

Dielectric behavior of water in biological solutions: Studies on myoglobin, human low‐density lipoprotein, and polyvinylpyrrolidone

On the theory of dielectric spectroscopy of protein solutions

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