Universal Convergence of the Specific Volume Changes of Globular Proteins upon Unfolding

Schweiker, Katrina L.; Fitz, Victoria W.; Makhatadze, George I.

doi:10.1021/bi901220u

Cited by 36 publications

(42 citation statements)

References 33 publications

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“…Second, in this and in previous studies (20,21) we find that pressure unfolding profiles shift to higher or lower pressures with changes in solution composition, but the volume changes remain constant, regardless of the pressure range over which the unfolding occurs. Moreover, measurements with PPC (22,23), which involve pressure changes of only 5 bar, reveal volume changes upon unfolding consistent with those measured using spectroscopic approaches.…”

Section: Discussionsupporting

confidence: 76%

“…In addition, the value of the volume change of unfolding is a strong function of temperature, both in magnitude and even in sign (25). Positive values of ΔV u have been measured at high temperature, resulting from a large difference in the coefficient of thermal expansion of the folded and unfolded states (23,26,27). Improved understanding of these effects will be required before successful structure-based predictions of pressure effects on proteins are possible.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Cavities determine the pressure unfolding of proteins

Roche

José

Norberto

et al. 2012

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

351

483

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It has been known for nearly 100 years that pressure unfolds proteins, yet the physical basis of this effect is not understood. Unfolding by pressure implies that the molar volume of the unfolded state of a protein is smaller than that of the folded state. This decrease in volume has been proposed to arise from differences between the density of bulk water and water associated with the protein, from pressure-dependent changes in the structure of bulk water, from the loss of internal cavities in the folded states of proteins, or from some combination of these three factors. Here, using 10 cavitycontaining variants of staphylococcal nuclease, we demonstrate that pressure unfolds proteins primarily as a result of cavities that are present in the folded state and absent in the unfolded one. High-pressure NMR spectroscopy and simulations constrained by the NMR data were used to describe structural and energetic details of the folding landscape of staphylococcal nuclease that are usually inaccessible with existing experimental approaches using harsher denaturants. Besides solving a 100-year-old conundrum concerning the detailed structural origins of pressure unfolding of proteins, these studies illustrate the promise of pressure perturbation as a unique tool for examining the roles of packing, conformational fluctuations, and water penetration as determinants of solution properties of proteins, and for detecting folding intermediates and other structural details of protein-folding landscapes that are invisible to standard experimental approaches.energy landscape | fluorescence | volume change T he first observation that pressure unfolds proteins was made in 1914 by Bridgman (1). Despite numerous studies since then, the physical basis of the pressure-induced unfolding of proteins has not been explained. This difference in volume underlying pressure effects has been rationalized previously in terms of (i) increases in solvent density concomitant with solvation of exposed surfaces upon unfolding (2), (ii) modifications in the structure of bulk water leading to weakened hydrophobic interactions (3), and (iii) cavities in the folded state that are not present in the unfolded state (4-7). The goal of this study was to examine the structural origins of pressure unfolding of proteins. Twenty-five years ago Walter Kauzmann stressed the importance of understanding pressure effects (8): "Enthalpy and volume are equally fundamental properties of the (protein) unfolding process, and no model can be considered acceptable unless it accounts for the entire thermodynamic behavior." He also noted important discrepancies between the volumetric properties of hydrophobic interactions and the pressure unfolding of proteins.To date, no conclusive explanation for the origins of pressure unfolding of proteins has been proposed. In the present work, 10 cavity-containing variants of staphylococcal nuclease (SNase) were engineered by substitution of internal core residues to Ala. Crystal structures of the variants were obtained to verify the exi...

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Section: Discussionsupporting

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Cavities determine the pressure unfolding of proteins

Roche

José

Norberto

et al. 2012

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

351

483

View full text Add to dashboard Cite

show abstract

“…Schweiker et al [37] performed a concise PPC study on volume changes of various small globular proteins (cytochrome c, lysozyme, ribonuclease A, ubiquitin, and eglin C) and two cavity mutants of eglin c, where an additional cavity in the core of the wild type of the protein was introduced by substitution of the larger valine amino acid residue to alanine. Using linear extrapolation of relative volume changes, DV/V, measured as a function of temperature, the authors showed that DV/V of proteins sharing the same intrinsic packing density converge to a common value at high temperatures, T ⁄ % 140°C, while others with more expanded structures -the two cavity-containing eglin c variants and cytochrome c -display significantly higher values of DV/V.…”

Section: Temperature Dependence Of the Volume Change Of Unfoldingmentioning

confidence: 99%

Probing volumetric properties of biomolecular systems by pressure perturbation calorimetry (PPC) – The effects of hydration, cosolvents and crowding

Suladze

Kahse

Erwin

et al. 2015

Methods

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“…Despite the laborious nature of pressure techniques, numerous studies were devoted to determine the thermodynamic properties of pressure-induced protein unfolding [1][2][3][4][5][6][7][8][9][10][11][12][13]. Relatively high pressures are required to determine the volumetric properties of proteins, and that is probably the most serious obstacle for the pressure to become a standard descriptor of the thermodynamic state of a protein.…”

Section: Introductionmentioning

confidence: 99%