Editing Hydrophobic effect (section)

{{Short description|Aggregation of non-polar molecules in aqueous solutions}}
[[Image: Water drop on a leaf.jpg|thumbnail|250px|A droplet of water forms a spherical shape, minimizing contact with the hydrophobic leaf.]]
[[File:Dutch process and natural cocoa.jpg|thumb|Cocoa powder, an example of a "hydrophobic substance".]]
The '''hydrophobic effect''' is the observed tendency of [[nonpolar]] substances to aggregate in an [[aqueous solution]] and to be excluded by [[water#Properties|water]].<ref>{{GoldBookRef|title=hydrophobic interaction|file=H02907}}</ref><ref name="pmid16193038">{{cite journal | vauthors = Chandler D | title = Interfaces and the driving force of hydrophobic assembly | journal = Nature | volume = 437 | issue = 7059 | pages = 640–7 | year = 2005 | pmid = 16193038 | doi = 10.1038/nature04162 | bibcode = 2005Natur.437..640C | s2cid = 205210634 }}</ref>  The word hydrophobic literally means "water-fearing", and it describes the [[Segregation in materials|segregation]] of water and nonpolar substances, which maximizes the [[entropy]] of water and minimizes the area of contact between water and nonpolar molecules. In terms of thermodynamics, the hydrophobic effect is the free energy change of water surrounding a solute.<ref name='pmimd27442443'>{{cite journal |last1=Schauperl |first1=M |last2=Podewitz |first2=M |last3=Waldner |first3=BJ |last4=Liedl |first4=KR |title=Enthalpic and Entropic Contributions to Hydrophobicity. |journal=Journal of Chemical Theory and Computation |volume=12 |issue=9 |pages=4600–10 |year = 2016 |doi=10.1021/acs.jctc.6b00422 |pmid=27442443 |pmc=5024328}}</ref> A positive free energy change of the surrounding solvent indicates hydrophobicity, whereas a negative free energy change implies hydrophilicity.

The hydrophobic effect is responsible for the separation of a mixture of oil and water into its two components.  It is also responsible for effects related to biology, including: [[cell membrane]] and vesicle formation, [[protein folding]], insertion of [[membrane protein]]s into the nonpolar lipid environment and protein-[[small molecule]] associations.  Hence the hydrophobic effect is essential to life.<ref>{{cite book | vauthors = Kauzmann W | title = Advances in Protein Chemistry Volume 14 | chapter = Some factors in the interpretation of protein denaturation | journal = Advances in Protein Chemistry | volume = 14 | pages = 1–63 | year = 1959 | publisher = Academic Press | pmid = 14404936 | doi = 10.1016/S0065-3233(08)60608-7 | isbn = 9780120342143 }}</ref><ref>{{cite journal | vauthors = Charton M, Charton BI | title = The structural dependence of amino acid hydrophobicity parameters | journal = Journal of Theoretical Biology | volume = 99 | issue = 4 | pages = 629–644 | year = 1982 | pmid = 7183857 | doi = 10.1016/0022-5193(82)90191-6 | bibcode = 1982JThBi..99..629C }}</ref><ref name="pmid23788494">{{cite journal | vauthors = Lockett MR, Lange H, Breiten B, Heroux A, Sherman W, Rappoport D, Yau PO, Snyder PW, Whitesides GM | title = The binding of benzoarylsulfonamide ligands to human carbonic anhydrase is insensitive to formal fluorination of the ligand | journal = Angew. Chem. Int. Ed. Engl. | volume = 52 | issue = 30 | pages = 7714–7 | year = 2013 | pmid = 23788494 | doi = 10.1002/anie.201301813 | s2cid = 1543705 | url = http://nrs.harvard.edu/urn-3:HUL.InstRepos:12362620| url-access = subscription }}</ref><ref name="pmid24044696">{{cite journal | vauthors = Breiten B, Lockett MR, Sherman W, Fujita S, Al-Sayah M, Lange H, Bowers CM, Heroux A, Krilov G, Whitesides GM | title = Water networks contribute to enthalpy/entropy compensation in protein-ligand binding | journal = J. Am. Chem. Soc. | volume = 135 | issue = 41 | pages = 15579–84 | year = 2013 | pmid = 24044696 | doi = 10.1021/ja4075776 | bibcode = 2013JAChS.13515579B | citeseerx = 10.1.1.646.8648 | s2cid = 17554787 }}</ref> Substances for which this effect is observed are known as [[hydrophobe]]s.