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{{Short description|Solvent interface of a solute}}

[[File:Na+H2O.svg|thumb|right|The first solvation shell of a [[sodium]] [[ion]] dissolved in water]]
[[File:Na+H2O.svg|thumb|right|The first solvation shell of a [[sodium]] [[ion]] dissolved in water]]


A '''solvation shell''' is the solvent interface of any [[chemical compound]] or biomolecule that constitutes the [[Solution|solute]]. When the solvent is [[water]] it is often referred to as a '''hydration shell''' or '''hydration sphere'''. The number of solvent molecules surrounding each unit of solute is called the [[hydration number]] of the solute.
A '''solvation shell''' or '''solvation sheath''' is the solvent interface of any [[chemical compound]] or biomolecule that constitutes the [[solute]] in a [[Solution (chemistry)|solution]]. When the solvent is [[water]] it is called a '''hydration shell''' or '''hydration sphere'''. The number of solvent molecules surrounding each unit of solute is called the [[hydration number]] of the solute.


A classic example is when water molecules arrange around a metal ion. For example, if the latter were a cation, the [[electronegative]] oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules that surround the ion. This shell can be several molecules thick, dependent upon the charge of the ion, its distribution and spatial dimensions.
A classic example is when water molecules arrange around a metal ion. If the metal ion is a cation, the [[electronegative]] oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules that surround the ion. This shell can be several molecules thick, dependent upon the charge of the ion, its distribution and spatial dimensions.


A number of molecules of solvent is involved in the solvation shell around anions and cations from a dissolved salt in a solvent. [[Metal ions in aqueous solution]]s form [[metal aquo complex]]es. This number can be determined by various methods like compressibility and NMR measurements among others.
A number of molecules of solvent are involved in the solvation shell around anions and cations from a dissolved salt in a solvent. [[Metal ions in aqueous solution]]s form [[metal aquo complex]]es. This number can be determined by various methods like compressibility and NMR measurements among others.


==Relation to activity coefficient of an electrolyte and its solvation shell number==
==Relation to activity coefficient of an electrolyte and its solvation shell number==
The solvation shell number of an dissolved electrolyte can be linked to the statistical component of the [[activity coefficient]] of the electrolyte and to the ratio between the apparent molar volume of a dissolved electrolyte in a concentrated solution and the molar volume of the solvent (water):
The solvation shell number of a dissolved electrolyte can be linked to the statistical component of the [[activity coefficient]] of the electrolyte and to the ratio between the apparent molar volume of a dissolved electrolyte in a concentrated solution and the molar volume of the solvent (water):{{clarify|date=January 2021 |reason= What do these symbols b,r,h,nu mean? Need definitions. Also, when is this equation applicable / inapplicable? }}


<math>ln \gamma_s = \frac{h- \nu}{\nu} ln (1 + \frac{br}{55.5}) - \frac{h}{\nu} ln (1 - \frac{br}{55.5}) + \frac{br(r + h -\nu)}{55.5 (1 + \frac{br}{55.5})}</math><ref>http://pubs.rsc.org/en/content/articlelanding/1955/tf/tf9555101235#!divAbstract</ref>
<math>\ln \gamma_s = \frac{h- \nu}{\nu} \ln \left(1 + \frac{br}{55.5} \right) - \frac{h}{\nu} \ln \left(1 - \frac{br}{55.5} \right) + \frac{br(r + h -\nu)}{55.5 \left(1 + \frac{br}{55.5} \right)}</math><ref>{{Cite journal |doi = 10.1039/TF9555101235|title = The influence of ionic hydration on activity coefficients in concentrated electrolyte solutions|journal = Transactions of the Faraday Society|volume = 51|pages = 1235|year = 1955|last1 = Glueckauf|first1 = E.}}</ref>


==Hydration shells of proteins==
==Hydration shells of proteins==


The hydration shell (also sometimes called hydration layer) that forms around proteins is of particular importance in biochemistry. This interaction of the protein surface with the surrounding water is often referred to as protein hydration and is fundamental to the activity of the protein.<ref name="Mapping hydration dynamics">{{Cite journal | doi = 10.1073/pnas.0707647104 | pmc = 2141799 | title = Mapping hydration dynamics around a protein surface | pmid = 18003912 | year = 2007 | last1 = Zhang | first1 = L. | last2 = Wang | first2 = L. | last3 = Kao | first3 = Y. -T. | last4 = Qiu | first4 = W. | last5 = Yang | first5 = Y. | last6 = Okobiah | first6 = O. | last7 = Zhong | first7 = D. | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 47 | pages = 18461–18466 |bibcode = 2007PNAS..10418461Z }}</ref> The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1&nbsp;nm. The duration of contact of a specific water molecule with the protein surface may be in the subnanosecond range while [[molecular dynamics]] simulations suggest the time water spends in the hydration shell before mixing with the outside bulk water could be in the femtosecond to picosecond range.<ref name="Mapping hydration dynamics" />
The hydration shell (also sometimes called hydration layer) that forms around proteins is of particular importance in biochemistry. This interaction of the protein surface with the surrounding water is often referred to as protein hydration and is fundamental to the activity of the protein.<ref name="Mapping hydration dynamics">{{Cite journal | doi = 10.1073/pnas.0707647104 | pmc = 2141799 | title = Mapping hydration dynamics around a protein surface | pmid = 18003912 | year = 2007 | last1 = Zhang | first1 = L. | last2 = Wang | first2 = L. | last3 = Kao | first3 = Y. -T. | last4 = Qiu | first4 = W. | last5 = Yang | first5 = Y. | last6 = Okobiah | first6 = O. | last7 = Zhong | first7 = D. | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 47 | pages = 18461–18466 |bibcode = 2007PNAS..10418461Z | doi-access = free }}</ref> The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1&nbsp;nm. The duration of contact of a specific water molecule with the protein surface may be in the subnanosecond range while [[molecular dynamics]] simulations suggest the time water spends in the hydration shell before mixing with the outside bulk water could be in the femtosecond to picosecond range,<ref name="Mapping hydration dynamics" /> and that near features conventionally regarded as attractive to water, such as hydrogen bond donors, the water molecules are actually relatively weakly bound and are easily displaced.<ref name="Large-Scale Study of Hydration Environments through Hydration Sites">{{Citation | journal = J. Phys. Chem. B | doi = 10.1021/acs.jpcb.9b02490 | title = Large-Scale Study of Hydration Environments through Hydration Sites | pmid = 31025866 | year = 2019 | last1 = Irwin | first1 = B. W. J. | last2 = Vukovic | first2 = S. | last3 = Payne | first3 = M. C. | last4 = Huggins | first4 = D. J. | volume = 123 | issue = 19 | pages = 4220–4229 | s2cid = 133608762 | url = https://www.repository.cam.ac.uk/handle/1810/292377 }}</ref> Solvation shell water molecules can also influence the molecular design of protein binders or inhibitors.<ref name="Free Energy Calculations of Mutations Involving a Tightly Bound Water Molecule and Ligand Substitutions in a Ligand Protein Complex">{{Citation | journal = Molecular Informatics | doi = 10.1002/minf.201000007 | title = Free Energy Calculations of Mutations Involving a Tightly Bound Water Molecule and Ligand Substitutions in a Ligand Protein Complex | pmid = 27463454 | year = 2010 | last1 = Garcia-Sosa | first1 = A. T. | last2 = Mancera | first2 = R. L.| volume = 29 | issue = 8–9 | pages = 589–600 | s2cid = 7225264 | url = https://onlinelibrary.wiley.com/doi/full/10.1002/minf.201000007 }}</ref>


With other solvents and solutes, varying steric and kinetic factors can also affect the solvation shell.
With other solvents and solutes, varying steric and kinetic factors can also affect the solvation shell.

===Dehydrons===
A dehydron is a backbone [[hydrogen bond]] in a protein that is incompletely shielded from water attack and has a propensity to promote its own [[dehydration]], a process both [[energy|energetically]] and [[thermodynamics|thermodynamically]] favored.<ref name=FernandezRev2008>{{cite journal | last1 = Fernández | first1 = A | last2 = Crespo | first2 = A | date = Nov 2008 | title = Protein wrapping: a molecular marker for association, aggregation and drug design | url = | journal = Chem Soc Rev | volume = 37 | issue = 11| pages = 2373–82 | doi = 10.1039/b804150b | pmid = 18949110 }}</ref><ref>{{cite journal | last1 = Ball | first1 = [[Philip Ball|P]] | date = Jan 2008 | title = Water as an active constituent in cell biology | url = | journal = Chem. Rev. | volume = 108 | issue = 1| pages = 74–108 | doi = 10.1021/cr068037a | pmid=18095715}}</ref> They result from an incomplete clustering of side-chain [[nonpolar]] groups that "wrap" the [[Chemical polarity|polar]] pair within the [[protein structure]]. Dehydrons promote the removal of surrounding water through [[proteins|protein associations]] or [[ligand|ligand binding]].<ref name=FernandezRev2008/> Dehydrons can be identified by calculating the reversible work per unit area required to span the aqueous interface of a soluble protein, or the "epistructural tension" at the interface.<ref name=PhysRev>{{cite journal | last1 = Fernández | first1 = A | date = May 2012 | title = Epistructural tension promotes protein associations | url = | journal = Phys. Rev. Lett. | volume = 108 | issue = 18| page = 188102 | pmid = 22681121 | doi=10.1103/physrevlett.108.188102| bibcode = 2012PhRvL.108r8102F}} Lay summary: [http://physics.aps.org/articles/v5/51 Proteins hook up where water allows]</ref><ref name=WrapBook/>{{rp|217–33}} Once identified, dehydrons can be used in [[drug discovery]], both to identify new compounds and to optimize existing compounds; chemicals can be [[Drug design|designed]] to "wrap" or shield dehydrons from water attack upon association with the target.<ref name=FernandezRev2008/><ref name=WrapBook>Ariel Fernandez. Transformative Concepts for Drug Design: Target Wrapping: Target Wrapping. Springer Science & Business Media, 2010. {{ISBN|978-3-642-11791-6}}</ref>{{rp|1–15}}<ref name=Demetri>{{cite journal | last1 = Demetri | first1 = GD | date = Dec 2007 | title = Structural reengineering of imatinib to decrease cardiac risk in cancer therapy | url = | journal = J Clin Invest | volume = 117 | issue = 12| pages = 3650–3 | doi = 10.1172/JCI34252 | pmid=18060025 | pmc = 2096446 }}</ref><ref name=Crunkhorn>Sarah Crunkhorn for Nature Reviews Drug Discovery. February 2008. [http://www.nature.com/nrd/journal/v7/n2/full/nrd2524.html Research Highlight: Anticancer drugs: Redesigning kinase inhibitors].</ref>


==See also==
==See also==
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*[[Metal ions in aqueous solution]]
*[[Metal ions in aqueous solution]]
*[[Ion transport number]]
*[[Ion transport number]]
*[[Ionic radius]]
*[[Water model]]
*[[Water model]]
*[[Poisson-Boltzmann equation]]
*[[Poisson-Boltzmann equation]]
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{{reflist}}
{{reflist}}


⚫
{{Chemical solutions|state=collapsed}}
==External links==

* [http://www1.lsbu.ac.uk/water/protein.html London South Bank University pages on protein hydration]
* [http://jcp.aip.org/resource/1/jcpsa6/v36/i12/p3382_s1?isAuthorized=no Journal of Chemical Physics]
* [https://books.google.ro/books?id=DF-1K6weadgC&pg=PA44&lpg=PA44&dq=baxendale+1964+solvated+electron&source=bl&ots=Fs5f5UoW0e&sig=dBSdeFfUW9rWhJDWeVQgyBpR1j4&hl=en&sa=X&ved=0ahUKEwiZjKTE98DPAhWDaxQKHX8zBmMQ6AEIITAB#v=onepage&q=baxendale%201964%20solvated%20electron&f=false Book]
⚫
{{Chemical solutions}}


{{DEFAULTSORT:Solvation Shell}}
{{DEFAULTSORT:Solvation Shell}}
[[Category:Solutions]]
[[Category:Solutions]]
[[Category:Chemical properties]]
[[Category:Chemical bonding]]

Latest revision as of 09:58, 7 January 2024

The first solvation shell of a sodium ion dissolved in water

A solvation shell or solvation sheath is the solvent interface of any chemical compound or biomolecule that constitutes the solute in a solution. When the solvent is water it is called a hydration shell or hydration sphere. The number of solvent molecules surrounding each unit of solute is called the hydration number of the solute.

A classic example is when water molecules arrange around a metal ion. If the metal ion is a cation, the electronegative oxygen atom of the water molecule would be attracted electrostatically to the positive charge on the metal ion. The result is a solvation shell of water molecules that surround the ion. This shell can be several molecules thick, dependent upon the charge of the ion, its distribution and spatial dimensions.

A number of molecules of solvent are involved in the solvation shell around anions and cations from a dissolved salt in a solvent. Metal ions in aqueous solutions form metal aquo complexes. This number can be determined by various methods like compressibility and NMR measurements among others.

Relation to activity coefficient of an electrolyte and its solvation shell number

[edit]

The solvation shell number of a dissolved electrolyte can be linked to the statistical component of the activity coefficient of the electrolyte and to the ratio between the apparent molar volume of a dissolved electrolyte in a concentrated solution and the molar volume of the solvent (water):[clarification needed]

[1]

Hydration shells of proteins

[edit]

The hydration shell (also sometimes called hydration layer) that forms around proteins is of particular importance in biochemistry. This interaction of the protein surface with the surrounding water is often referred to as protein hydration and is fundamental to the activity of the protein.[2] The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1 nm. The duration of contact of a specific water molecule with the protein surface may be in the subnanosecond range while molecular dynamics simulations suggest the time water spends in the hydration shell before mixing with the outside bulk water could be in the femtosecond to picosecond range,[2] and that near features conventionally regarded as attractive to water, such as hydrogen bond donors, the water molecules are actually relatively weakly bound and are easily displaced.[3] Solvation shell water molecules can also influence the molecular design of protein binders or inhibitors.[4]

With other solvents and solutes, varying steric and kinetic factors can also affect the solvation shell.

See also

[edit]

References

[edit]
  1. ^ Glueckauf, E. (1955). "The influence of ionic hydration on activity coefficients in concentrated electrolyte solutions". Transactions of the Faraday Society. 51: 1235. doi:10.1039/TF9555101235.
  2. ^ a b Zhang, L.; Wang, L.; Kao, Y. -T.; Qiu, W.; Yang, Y.; Okobiah, O.; Zhong, D. (2007). "Mapping hydration dynamics around a protein surface". Proceedings of the National Academy of Sciences. 104 (47): 18461–18466. Bibcode:2007PNAS..10418461Z. doi:10.1073/pnas.0707647104. PMC 2141799. PMID 18003912.
  3. ^ Irwin, B. W. J.; Vukovic, S.; Payne, M. C.; Huggins, D. J. (2019), "Large-Scale Study of Hydration Environments through Hydration Sites", J. Phys. Chem. B, 123 (19): 4220–4229, doi:10.1021/acs.jpcb.9b02490, PMID 31025866, S2CID 133608762
  4. ^ Garcia-Sosa, A. T.; Mancera, R. L. (2010), "Free Energy Calculations of Mutations Involving a Tightly Bound Water Molecule and Ligand Substitutions in a Ligand Protein Complex", Molecular Informatics, 29 (8–9): 589–600, doi:10.1002/minf.201000007, PMID 27463454, S2CID 7225264
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