Driving Force Behind Adsorption-Induced Protein Unfolding: A Time-Resolved X-ray Reflectivity Study on Lysozyme Adsorbed at an Air/Water Interface

Yano, Yohko F.; Uruga, Tomoya; Tanida, Hajime; Toyokawa, H.; Terada, Yasuko; Takagaki, Masafumi; Yamada, Hironari

doi:10.1021/la803235x

Cited by 79 publications

(86 citation statements)

References 18 publications

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“…23 We found that the LSZ molecule initially adsorbed by adopting a flat, unfolded structure as a result of hydrophobic interactions with the gas phase. In contrast, as adsorption continues, the LSZ molecules gradually adapt their configuration to the surroundings.…”

Section: Section: Macromolecules Soft Mattermentioning

confidence: 86%

Protein Salting Out Observed at an Air−Water Interface

Yano

Uruga

Tanida

et al. 2011

J. Phys. Chem. Lett.

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b S Supporting Information P rotein crystallization is typically realized by the addition of a salt or an organic solvent to a supersaturated protein solution to decrease the protein solubility. "Salting out" is a method for separating proteins, in which the hydrated salt ions reduce the number of water molecules available for interaction with the proteins. Protein solubility is a macroscopic property resulting from various molecular interactions, including proteinÀprotein, proteinÀion, ionÀwater, and waterÀprotein interactions, and depends on temperature, pH, ion species, and concentration. At low salt concentrations, a "salting-in" region exists, where favorable interactions occur between the protein surface charges and the salt ions in solution to increase protein solubility, which is sometimes associated with protein unfolding. At higher salt concentrations, the repulsive electrostatic interactions are screened, resulting in protein stabilization, and proteinÀprotein interactions such as hydrophobic interactions and dispersion forces can drive aggregation and precipitation. 1À4 The effect of ion species on the solubility of proteins is classified by the well-known Hofmeister series, defined by the concentration of a particular salt needed to precipitate proteins from whole egg white. 5,6 The series are usually given in terms of the ability of the ions to stabilize the structure of proteins. Although Hofmeister ion effects on protein stability are widely reported in protein research, the mechanism is not entirely clear to date. Most previous research on Hofmeister ion effects on proteinÀprotein interactions has been performed in bulk liquids by varying ion species and concentration. 4,7À11The surface tension, that is, the surface free energy per area, can be regarded as the work in bringing a molecule from the interior of a liquid to the surface and is strongly affected by molecular forces and configurations. 12 When salt ions dissociate in water, the magnitude of the surface tension increment indicates the energy required to separate the ions from the water molecules. The molar surface tension increment of the salt has been known to follow the rank order of the Hofmeister series. 13À15 Several recent experiments and computer simulations 16 looking at interfaces have revealed that the propensity for salt anions to adsorb at an airÀwater interface follows an inverse Hofmeister series, that is, strongly hydrated anions effective in precipitating proteins do not adsorb at the airÀwater interface and vice versa. 17 These results suggest that studying the surface adsorption of proteins in a salt solution could provide valuable insight into the salting out of proteins generally.Proteins adsorb at airÀwater interfaces as surfactants. The effect of salt on protein adsorption under equilibrium conditions has been studied by surface pressure measurements, surfacespecific spectroscopies, and neutron reflectometry. 18À22 The amount of adsorption and the thickness of the interfacial layer are strongly dependent on the ...

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Section: Section: Macromolecules Soft Mattermentioning

confidence: 86%

Protein Salting Out Observed at an Air−Water Interface

Yano

Uruga

Tanida

et al. 2011

J. Phys. Chem. Lett.

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“…These differences can be explained by the stronger effect of the interface on the structure of lysozyme compared to BSA and BLG. In [7], it was revealed that the second ary structure of lysozyme changes more markedly dur ing the adsorption than do the structures of the two lat ter proteins. Seemingly, when lysozyme complexes with several SDS molecules are adsorbed in the region of specific binding, the tertiary structure is also some what changed and the adsorption film becomes looser.…”

Section: Resultsmentioning

confidence: 99%

“…The degree of the breakage of the globular structure of proteins upon their adsorption on a liquid surface is still intensely discussed [1][2][3][4][5][6][7][8][9][10][11]. Although the main stages of many processes in living organisms occur at interfaces and protein adsorption layers stabilize vari ous natural and industrial disperse systems, informa tion on variations in the tertiary and secondary struc tures of proteins during adsorption is extremely scarce.…”

Section: Introductionmentioning

confidence: 99%

“…Although the main stages of many processes in living organisms occur at interfaces and protein adsorption layers stabilize vari ous natural and industrial disperse systems, informa tion on variations in the tertiary and secondary struc tures of proteins during adsorption is extremely scarce. While the mechanisms of unfolding protein globules in bulk phases have been studied in detail [12], in the case of surface layers, different authors give directly opposite answers even to the main question concern ing breaking or retaining the tertiary structure of pro teins upon adsorption [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…Subsequently, using the neutron reflection method, it was shown that proteins retain a globular structure in surface layers [4,6,7,15,16]. However, the methods of X ray reflection and circular dichroism have not confirmed this con clusion for some systems [1,2,7].…”

Section: Introductionmentioning

confidence: 99%

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Effect of sodium dodecyl sulfate on dynamic surface properties of lysozyme solutions

Noskov

Tikhonov

2012

Colloid J

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The surface dilatation rheological properties of lysozyme/sodium dodecyl sulfate (SDS) mixed solutions are studied by the oscillating ring method. At the initial stage of adsorption, the rate of variations in the surface properties depends nonmonotonically on SDS concentration due to the reversal of the lysozyme/SDS complex charge with increasing degree of surfactant binding. The nonmonotonic kinetic dependences of the dynamic surface elasticity indicate the breakage of the secondary and tertiary structures of the protein in the surface layer. For lysozyme/SDS solutions, the denaturing effect of the interface appears to be stronger than for previously studied systems, namely, bovine serum albumin/dodecyltrimethylammo nium bromide and β lactoglobulin/dodecyltrimethylammonium bromide.

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Nucleation, Aggregation, and Conformational Distortion

Roberts

2014

Biophysical Methods for Biotherapeutics

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Driving Force Behind Adsorption-Induced Protein Unfolding: A Time-Resolved X-ray Reflectivity Study on Lysozyme Adsorbed at an Air/Water Interface

Cited by 79 publications

References 18 publications

Protein Salting Out Observed at an Air−Water Interface

Protein Salting Out Observed at an Air−Water Interface

Effect of sodium dodecyl sulfate on dynamic surface properties of lysozyme solutions

Nucleation, Aggregation, and Conformational Distortion

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