Dielectric and electrical properties of hydrated bovine serum albumin

Eden, Joyce; Gascoyne, Peter R. C.; Pethig, Ronald

doi:10.1039/f19807600426

Cited by 59 publications

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“…The steady-state conductivity has also been found (14) to be strongly dependent on hydration, and the typical result obtained for albumin is shown in Fig. 3.…”

mentioning

confidence: 89%

“…1 a large dielectric loss peak is seen to occur at very low frequencies, and this has been the most fully characterized for hemoglobin (13) and albumin (14). The relaxation time Tthat characterizes this low-frequency dielectric loss follows a temperature-activated law of the form [2] with the relaxation activation energy W having a value very similar to the activation energy E observed for the steady-state conductivity o given by or = 0oexp(-E/kT).…”

mentioning

confidence: 93%

“…HYDRATION EFFECTS With increasing protein hydration, the low-frequency dielectric dispersion has been found to progressively shift to higher frequencies (14), with the effective value for NMi2 remaining unchanged. Defining the characteristic relaxation time T by 1/ 2lfm, in whichfm is the frequency at the maximum of the loss peak, then from the data ofref.…”

mentioning

confidence: 99%

“…2 The weak high-frequency dielectric absorption depicted in Fig. 1 for albumin as accompanied by a reduction ofthe real part of the relative permittivity of magnitude As 0.46 (14). From…”

mentioning

confidence: 99%

“…Support for this conclusion is given by a close analysis of dielectric measurements for. hydrated albumin (14,18), which yields values for the effective dipole moment of the water molecules bound to the protein surface. A detailed account ofthis analysis will be published separately and we wish here to indicate the main result as shown in Fig.…”

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confidence: 99%

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Water structure-dependent charge transport in proteins.

Gascoyne¹,

Pethig²,

Szent‐Györgyi³

1981

Proc. Natl. Acad. Sci. U.S.A.

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Dielectric and conductivity measurements are reported for bovine serum albumin as a function of hydration. Strong evidence is found for the existence ofmobile charges whose short-and long-range hopping motion strongly depends on the physical state of the protein-bound water. These charges are considered to be protons. Insights into the nature of the electrical properties of protein-methylglyoxal complexes are provided, and the possibilities for correlated proton-electron motions are outlined.Modern biology is a molecular biology. The rates of most biological reactions are assumed to be limited by the classical concepts of mass action theories applicable to reacting molecules in solution. The main bearers oflife are the protein macromolecules, which are often to be found incorporated into membrane structures. This situation would appear to violate the physical basis ofclassical mass action theories and suggests that the functioning of such structural proteins is controlled at the submolecular level. The reactivity and subtlety that characterizes living systems also indicates that at its most fundamental level the "living state" operates at the submolecular level of nuclei and electrons (1). Such considerations ofthe reactivity of living systems led one of us to suggest nearly 40 years ago that the functioning of proteins should be understood by considering their submolecular properties. It was envisaged that one manifestation of such submolecular processes would be the ability of proteins to sustain electrical conductivity (2). However, as shown by the pioneering studies ofEley (3, 4), proteins isolated in their pure and dry condition are poor conductors. The basic reason for this is that the valence and conduction levels of extended electronic states of protein structures are separated by such a wide energy gap that at normal temperatures there is a negligible probability for the intrinsic generation of mobile charge carriers. Formation of charge-transfer complexes with electron-accepting molecules makes it possible for the electronic ground states ofa protein to become desaturated ofelectronic charge and lead to a conductivity sustained by positively charged electron "holes." Similarly, a charge-transfer interaction with an electron donor could result in the appearance of mobile electrons in the protein's conduction energy levels. The possibility that proteins can be so converted from insulators into conductors has been demonstrated by Eley and coworkers (5, 6) in conduction studies on complexes ofbovine plasma albumin with chloranil or chlorophyll, and our own studies (7-9) indicate the possibility that aldehydes such as methylglyoxal can act as electron acceptors in charge-transfer interactions with proteins. We believe that it is through such charge transfer that structural proteins are imbued with a submolecular reactivity that is essential for their full biological functioning.Our attempts to fully understand the basic process by which methylglyoxal, when incorporated into a protein's structure, in...

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“…The steady-state conductivity has also been found (14) to be strongly dependent on hydration, and the typical result obtained for albumin is shown in Fig. 3.…”

mentioning

confidence: 89%

mentioning

confidence: 93%

mentioning

confidence: 99%

“…2 The weak high-frequency dielectric absorption depicted in Fig. 1 for albumin as accompanied by a reduction ofthe real part of the relative permittivity of magnitude As 0.46 (14). From…”

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Water structure-dependent charge transport in proteins.

Gascoyne¹,

Pethig²,

Szent‐Györgyi³

1981

Proc. Natl. Acad. Sci. U.S.A.

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Evidence for solid state electronic conductivity in mixtures of a porphyrin and its two‐electron oxidation product

Milgrom

Hill

Bone

1993

Adv Material for Optics Elec

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Dielectric properties of slightly hydrated collagen: Time–water content superposition analysis

Sasaki¹

1984

Biopolymers

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SynopsisThe frequency dependences of the dielectric constant, E ' , and the loss factor, E", in collagen were measured a t several water contents from 0.1 to 0.3 g/g collagen over a frequency range of 30 Hz to 100 kHz and at a temperature of 20°C. Remarkable dispersion was observed at the lower frequencies for higher water contents. According to accumulated results on the thermodynamic and structural investigations, the dispersion has some analogy to the surface conduction proposed by B. V. Hamon [(1953) Awt. J. Phys. 6, 304-3151. An empirical relation bewteen E" and frequency, E"= f", where 0 < n < 1, suggests that the dielectric and conductive properties of hydrated collagen are related to carrier jumps between neighboring sites. For the polarization mechanism of this dispersion, we supposed a model of the transfer of protons between absorbed water molecules, and found that the t i m e w a t e r content superposition procedure is applicable to slightly hydrated collagen. The results derived from the superposition procedure show that the water content, +, is related to the conductivity, r , or the dielectric loss factor by the following equations: r (+, f , = const. x +,zm-lf' and el' (+, f, = const.+""'f", respectively, where rn is a constant independent of + and f: These results agree with that derived by another treatment of the same data. The role of water molecules in the conduction and polarization in slightly hydrated collagen is considered to be not far from that assumed in the model.

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Dielectric and electrical properties of hydrated bovine serum albumin

Cited by 59 publications

References 0 publications

Water structure-dependent charge transport in proteins.

Water structure-dependent charge transport in proteins.

Evidence for solid state electronic conductivity in mixtures of a porphyrin and its two‐electron oxidation product

Dielectric properties of slightly hydrated collagen: Time–water content superposition analysis

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