Heat capacity of hydrated and dehydrated globular proteins. Denaturation increment of heat capacity

Sochava, I.V.; Smirnova, O. I.

doi:10.1016/s0268-005x(09)80075-1

Cited by 67 publications

(63 citation statements)

References 14 publications

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“…Kanehisa and Ikegami (1977) calculated a value of 0.105 J.g-l .K" from the infrared and Raman spectra of the 20 amino acids. More recently, Sochava and Smirnova (1993) obtained 0.190 J.g" .K", probably an overestimate, from calorimetric measurements done on several globular proteins at 4-7% moisture content. This value was virtually the same for the five proteins studied: ribonuclease, lysozyme, a-chymotrypsin, cytochrome c, and myoglobin.…”

Section: The Heat Capacity Of Protein Unfoldingmentioning

confidence: 98%

Thermodynamics of the temperature‐induced unfolding of globular proteins

1995

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The heat capacity, enthalpy, entropy, and Gibbs energy changes for the temperature-induced unfolding of 11 globular proteins of known three-dimensional structure have been obtained by microcalorimetric measurements. Their experimental values are compared to those we calculate from the change in solvent-accessible surface area between the native proteins and the extended polypeptide chain. We use proportionality coefficients for the transfer (hydration) of aliphatic, aromatic, and polar groups from gas phase to aqueous solution, we estimate vibrational effects, and we discuss the temperature dependence of each constituent of the thermodynamic functions. At 25 "C, stabilization of the native state of a globular protein is largely due to two favorable terms: the entropy of nonpolar group hydration and the enthalpy of interactions within the protein. They compensate the unfavorable entropy change associated with these interactions (conformational entropy) and with vibrational effects. Due to the large heat capacity of nonpolar group hydration, its stabilizing contribution decreases quickly at higher temperatures, and the two unfavorable entropy terms take over, leading to temperature-induced unfolding.Keywords: Gibbs energy; heat capacity; hydration; protein foldingThe stability of globular proteins is a delicate balance between enthalpic and entropic terms derived from the physical-chemical difference between the native and unfolded polypeptide chain and the surrounding solvent. Differential-scanning calorimetry (DSC) measures thermodynamical parameters for temperatureinduced unfolding: heat capacity, enthalpy, entropy, and Gibbs energy (Privalov, 1979;Privalov & Gill, 1988). These experimental values, which are relevant to the overall process of unfolding, should be interpreted as sums of a number of different contributions. The most significant are from changes in interactions between atoms within the polypeptide chain, in conformational degrees of freedom of the chain, in vibrational modes, and in the hydration of chemical groups. In cases where the three-dimensional structure of the native protein is known, the contribution of these changes to the thermodynamic parameters can in principle be calculated (see Creighton, 1991, for a review). To a good approximation, the contribution of hydration is additive (Murphy & Gill, 1990) and linearly related to the change in solvent-accessible surface area (Ooi et al., 1987). It can be derived with the help of proportionality coefficients derived from small molecule studies (Makhatadze & Privalov, 1988, 1990, 1994Ooi & Oobatake, 1988;Spolar et al., 1989Spolar et al., , 1992Khechinashvili, 1990; Reprint requests to: Joel Janin, Laboratoire de Biologie Structurale, UMR C9920, CNRS-Universite Paris-Sud, 91 198 Gif-sur-Yvette Cedex, France; e-mail: janin@cygne.lbs.cnrs-gif.fr. Livingstone et al., 1991;. The heat capacity change determines the evolution of other parameters with temperature, as opposed to their value at a given temperature. We present here estimates o...

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Section: The Heat Capacity Of Protein Unfoldingmentioning

confidence: 98%

Thermodynamics of the temperature‐induced unfolding of globular proteins

1995

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“…116 It would appear therefore that a-like motions, which are activated at T d , are not obvious by DSC measurements due to the continuous buildup of the lower energy, b-like motions through T d , where ultimately the two motions merge, giving rise to an apparent small change in DC p . 129,195 This behavior may help to explain the apparent fragility and ''T g ,'' determined by DSC measurements, for denatured aggregated proteins; which were generated by first unfolding the native protein with heat followed by cooling, such that the resulting protein structures are an assembly of non-native states 123,196 (Fig. 3).…”

Section: Local Dynamics In Globular Proteinsmentioning

confidence: 99%

Thermodynamic and dynamic factors involved in the stability of native protein structure in amorphous solids in relation to levels of hydration

Hill

Shalaev

Zografi

2005

Journal of Pharmaceutical Sciences

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“…The heat capacity change at T m , DC p (T m ), is large and comparable to the heat capacity of protein formulations in solution, 49 a result also noted by Sochava and Smirnova. 50 The transition being measured is that of protein unfolding and any subsequent process such as degradation. The fact that such unfolding takes place in a non-aqueous environment does not change the fact that this unfolding is just as much an unfolding process as is unfolding in dilute aqueous solution.…”

Section: Effect Of Sugars On Denaturation ''Thermodynamics''(dh M Andmentioning

confidence: 99%

Mechanism of protein stabilization by sugars during freeze-drying and storage: Native structure preservation, specific interaction, and/or immobilization in a glassy matrix?

Chang

Shepherd

Sun

et al. 2005

Journal of Pharmaceutical Sciences

391

325

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Heat capacity of hydrated and dehydrated globular proteins. Denaturation increment of heat capacity

Cited by 67 publications

References 14 publications

Thermodynamics of the temperature‐induced unfolding of globular proteins

Thermodynamics of the temperature‐induced unfolding of globular proteins

Thermodynamic and dynamic factors involved in the stability of native protein structure in amorphous solids in relation to levels of hydration

Mechanism of protein stabilization by sugars during freeze-drying and storage: Native structure preservation, specific interaction, and/or immobilization in a glassy matrix?

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