How Important is Entropy in Determining the Position-Dependent Free Energy of a Solute in a Nanoconfined Solvent?

Mitchell-Koch, Katie R.; Thompson, Ward H.

doi:10.1021/jp072580t

Cited by 19 publications

(37 citation statements)

References 55 publications

(87 reference statements)

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“…The ultrafast components of solvation (1 ps component for CPM labeled HSA in the presence of 1.5 M RTIL, 6 M GdnHCl, and both) may be attributed to the dielectric relaxation or librational motion of the bulk or, free water molecules. [32][33][34][35][36] There are several slow components of solvation of CPM covalently attached to HSA. In the native state, 30 ps and 800 ps components are observed.…”

Section: Solvation Dynamics Of Cpm Bound To Hsa: Effect Of Rtilmentioning

confidence: 99%

“…33,35 Recent theoretical studies predict that the protein is stabilized by quasi-stable hydrogen bonds ("pinning sites") leading to the formation of an hydrogen bond network around a protein. 34,[36][37][38][39] This hydrogen bond network and bound-to-free inter-conversion 35 is responsible for the slow solvation dynamics of the structured and quasi-bound water molecules ("biological water") around a protein. [32][33][34][35][36] In the presence of RTIL and GdnHCl in the immediate vicinity of the protein, many water molecules are replaced by ions.…”

Section: Solvation Dynamics Of Cpm Bound To Hsa: Effect Of Rtilmentioning

confidence: 99%

“…[15][16][17][18][19][20][21][22][23][24] and there is a considerable recent interest to understand dynamics of water near a protein. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Recent experimental, [25][26][27][28][29][30][31][32][39][40][41] theoretical, 34 and simulations [33][34][35][36][37][38] suggest that ''Biological Water'' near a protein could be 10 to 100 times slower than bulk water.…”

Section: Introductionmentioning

confidence: 99%

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Effect of ionic liquid on the native and denatured state of a protein covalently attached to a probe: Solvation dynamics study

Chowdhury

Mojumdar

Bhattacharyya

2012

The Journal of Chemical Physics

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Effect of a room temperature ionic liquid (RTIL, [pmim][Br]) on the solvation dynamics of a probe covalently attached to a protein (human serum albumin (HSA)) has been studied using femtosecond up-conversion. For this study, a solvation probe, 7-diethylamino-3-(4-maleimidophenyl)-4-methylcoumarin (CPM) has been covalently attached to the lone cysteine group (cys-34) of the protein HSA. Addition of 1.5 M RTIL or 6 M GdnHCl causes a red shift of the emission maxima of CPM bound to HSA by 3 nm and 12 nm, respectively. The average solvation time 〈τ(s)〉 decreases from 650 ps (in native HSA) to 260 ps (~2.5 times) in the presence of 1.5 M RTIL and to 60 ps (~11 times) in the presence of 6 M GdnHCl. This is ascribed to unfolding of the protein by RTIL or GdnHCl and therefore making the probe CPM more exposed. When 1.5 M RTIL is added to the protein denatured by 6 M GdnHCl in advance, a further ~5 nm red shift along with further ~2 fold faster solvent relaxation (<τ> ~30 ps) is observed. Our previous fluorescence correlation spectroscopy study [D. K. Sasmal, T. Mondal, S. Sen Mojumdar, A. Choudhury, R. Banerjee, and K. Bhattacharyya, J. Phys. Chem. B 115, 13075 (2011)] suggests that addition of RTIL to the protein denatured by 6 M GdnHCl causes a reduction in hydrodynamic radius (r(h)). It is demonstrated that in the presence of RTIL and GdnHCl, though the protein is structurally more compact, the local environment of CPM is very different from that in the native state.

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Section: Solvation Dynamics Of Cpm Bound To Hsa: Effect Of Rtilmentioning

confidence: 99%

Section: Solvation Dynamics Of Cpm Bound To Hsa: Effect Of Rtilmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of ionic liquid on the native and denatured state of a protein covalently attached to a probe: Solvation dynamics study

Chowdhury

Mojumdar

Bhattacharyya

2012

The Journal of Chemical Physics

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“…This will lay the groundwork for the tests of the accuracy of dynamic linear-response and Gaussian statistics approximations discussed below. One of us has shown previously, using Monte Carlo and MD simulations, that nanoconfined solvents exhibit a number of properties that are distinct from the corresponding bulk solvent 30,31,41,42 and that these can have signatures in simulations of the time-dependent fluorescence. 31 First, the solvent polarity depends strongly on the distance from the cavity wall.…”

Section: A Overview Of Time-dependent Fluorescence In Nanoconfined Smentioning

confidence: 99%

“…Additional discussion of the underlying free energy surfaces (and the internal energy and entropic contributions) can be found in Ref. 41.…”

Section: A Overview Of Time-dependent Fluorescence In Nanoconfined Smentioning

confidence: 99%

Time-dependent fluorescence in nanoconfined solvents: Linear-response approximations and Gaussian statistics

Laird

Thompson

2011

The Journal of Chemical Physics

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The time-dependent fluorescence of a model dye molecule in a nanoconfined solvent is used to test approximations based on the dynamic and static linear-response theories and the assumption of Gaussian statistics. Specifically, the results of nonequilibrium molecular-dynamics simulations are compared to approximate expressions involving time correlation functions obtained from equilibrium simulations. Solvation dynamics of a model diatomic dye molecule dissolved in acetonitrile confined in a spherical hydrophobic cavity of radius 12, 15, and 20 Å is used as the test case. Both the timedependent fluorescence energy, expressed as the normalized dynamic Stokes shift, and the timedependent position of the dye molecule after excitation are examined. While the dynamic linearresponse approximation fails to describe key aspects of the solvation dynamics, assuming Gaussian statistics reproduces the full nonequilibrium simulations well. The implications of these results are discussed.

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A Femtosecond Study of the Interaction of Human Serum Albumin with a Surfactant (SDS)

Mandal

Ghosh

Mitra

et al. 2008

Chemistry An Asian Journal

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The interaction of a protein, human serum albumin (HSA) with a surfactant (sodium dodecyl sulfate, SDS) was studied by femtosecond up-conversion. HSA was labeled covalently with a probe (CPM, 7-dimethylamino-3-(4-maleimidophenyl)-4-methylcoumarin). Binding of SDS to HSA is found to accelerate the solvation dynamics approximately 1.3-fold. The solvation dynamics in HSA displays two time components: 30 ps (20 %) and 800 ps (80 %). When approximately 10 SDS molecules bind to HSA the components are 15 ps (40 %) and 800 ps (60 %). It is argued that SDS may increase the solvent exposure of the probe (CPM); it may also displace the buried water molecules in the immediate vicinity of CPM.

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How Important is Entropy in Determining the Position-Dependent Free Energy of a Solute in a Nanoconfined Solvent?

Cited by 19 publications

References 55 publications

Effect of ionic liquid on the native and denatured state of a protein covalently attached to a probe: Solvation dynamics study

Effect of ionic liquid on the native and denatured state of a protein covalently attached to a probe: Solvation dynamics study

Time-dependent fluorescence in nanoconfined solvents: Linear-response approximations and Gaussian statistics

A Femtosecond Study of the Interaction of Human Serum Albumin with a Surfactant (SDS)

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