The heat capacity of proteins

Gómez, Javier; Hilser, Vincent J.; Xie, Donghua; Freire, Ernesto

doi:10.1002/prot.340220410

Cited by 443 publications

(449 citation statements)

References 25 publications

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“…3). Derived values for ΔH m and T m were relatively insensitive to ΔC p values within the range of 2-5 kcal mol −1 K −1 , which is consistent with previous experimentally determined values for proteins in general (21)(22)(23). All four cysteine mutants are thermally destabilized: the apparent T m values of SN variants F34C (40 AE 1°C) and L36C (39 AE 1°C) are ∼13.0°C below wild-type (53.0°C) (24); the apparent T m values of ecRBP variants L62C (54 AE 1°C) and A188C (56 AE 1°C) are ∼8°C below wild-type (62.6°C) (25).…”

Section: Resultssupporting

confidence: 88%

Picomole-scale characterization of protein stability and function by quantitative cysteine reactivity

Isom

Vardy

Oas

et al. 2010

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

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The Gibbs free energy difference between native and unfolded states ("stability") is one of the fundamental characteristics of a protein. By exploiting the thermodynamic linkage between ligand binding and stability, interactions of a protein with small molecules, nucleic acids, or other proteins can be detected and quantified. Determination of protein stability can therefore provide a universal monitor of biochemical function. Yet, the use of stability measurements as a functional probe is underutilized, because such experiments traditionally require large amounts of protein and special instrumentation. Here we present the quantitative cysteine reactivity (QCR) technique to determine protein stabilities rapidly and accurately using only picomole quantities of material and readily accessible laboratory equipment. We demonstrate that QCRderived stabilities can be used to measure ligand binding over a wide range of ligand concentrations and affinities. We anticipate that this technique will have broad applications in high-throughput protein engineering experiments and functional genomics. Macromolecular stability is therefore one of the most fundamental thermodynamic measures in biochemistry by quantitatively reporting on structure-function relationships to provide a universal monitor for biochemical function.There are two distinct approaches for determining protein stability (4). The first measures the free energy of protein (un)folding under equilibrium conditions by assessing the fraction of the native state using spectroscopy, hydrodynamic observations, functional assays, or calorimetry. The second exploits the relationship between protein dynamics and stability by monitoring the differential reactivity of internal chemical groups in native and unfolded states. This second approach measures conformational free energies, which under appropriate conditions corresponds to global protein stability. Amide proton exchange is used most commonly to monitor such differential reactivity (5-9), but its widespread use to assess biological function typically is limited by the need for specialized instrumentation and relatively large amounts of protein. Recently, cysteine reactivity (10-14) and proteolysis (15) have emerged as alternative means to determine rates of protein (un)folding and estimate protein stabilities. Here we present a method, quantitative cysteine reactivity (QCR), in which protein stability is determined by monitoring the reactivity of cysteine residues buried in the hydrophobic core of proteins. This approach has the advantage over more traditional methods for measuring protein stability in that it requires only picomoles (nanograms) of protein, uses simple instrumentation accessible to any lab, can be reasonably high throughput, and can provide site-specific thermodynamic information. QCR can be used to determine apparent protein stabilities rapidly and accurately, construct Gibbs-Helmholtz stability profiles, measure ligand binding over a large range of ligand concentrations and affinities, and infer e...

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Section: Resultssupporting

confidence: 88%

Picomole-scale characterization of protein stability and function by quantitative cysteine reactivity

Isom

Vardy

Oas

et al. 2010

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

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“…al. 53 considered the molecular weight and the accessible surface of the proteins, in order to fit heat capacities of proteins in the non-native state. Figure 5 clearly shows that the experimental results follow a linear dependence with the number of carbon atoms, as it would be expected from the extensive character of the heat capacity.…”

Section: Heat Capacity Of Proteinsmentioning

confidence: 99%

Heat transfer in protein–water interfaces

Lervik

Bresme

Kjelstrup

et al. 2010

Phys. Chem. Chem. Phys.

100

135

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We investigate using transient non-equilibrum molecular dynamics simulation the temperature relaxation process of three structurally different proteins in water, namely; myoglobin, green fluorescence protein (GFP) and two conformations of the Ca 2+ -ATPase protein. By modeling the temperature relaxation process using the solution of the heat conduction equation we compute the thermal conductivity and thermal diffusivity of the proteins, as well as the thermal conductance of the protein-water interface. Our results indicate that the temperature relaxation of the protein can be described using a macroscopic approach. The protein-water interface has a thermal conductance of the order of 100-270 MW m −2 K −1 , characteristic of water-hydrophilic interfaces. The thermal conductivity of the proteins is of the order of 0.1-0.2 † Imperial College and NTNU ‡ Imperial College and CAS ¶ NTNU and CAS § UB and CAS 1 Anders Lervik et al.Heat transfer in protein-water interfaces W m −1 K −1 as compared with ≈ 0.6 W m −1 K −1 for water, suggesting that these proteins can develop temperature gradients within the biomolecular structures that are larger than those of aqueous solutions. We find that the thermal diffusivity of the transmembrane protein, Ca 2+ -ATPase is about three times larger than that of myoglobin or GFP. Our simulation shows that the Kapitza length of these structurally different proteins is of the order of 1 nm, showing that the protein-water interface should play a major role in defining the thermal relaxation of biomolecules.

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“…Makhatadze and Privalov [61] gave extensive model compound data and used them to estimate contributions to the enthalpy and heat capacity changes on unfolding of all groups present in proteins. Freire and coworkers [62] used empirical calibration of protein unfolding data to give the contributions to DC p expected from the changes in polar and nonpolar ASA on unfolding. The issue is seriously complicated, however, by evidence from the study of model compounds that the enthalpies of interaction with water are not related in any simple way to polar ASA: see Table 6.2 and Section 6.3.2.…”

Section: 29mentioning

confidence: 99%

Weak Interactions in Protein Folding: Hydrophobic Free Energy, van der Waals Interactions, Peptide Hydrogen Bonds, and Peptide Solvation

Baldwin¹

2005

Protein Folding Handbook

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The heat capacity of proteins

Cited by 443 publications

References 25 publications

Picomole-scale characterization of protein stability and function by quantitative cysteine reactivity

Picomole-scale characterization of protein stability and function by quantitative cysteine reactivity

Heat transfer in protein–water interfaces

Weak Interactions in Protein Folding: Hydrophobic Free Energy, van der Waals Interactions, Peptide Hydrogen Bonds, and Peptide Solvation

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