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Topic: Hydrophobic effect

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	Hydrophobic hydration
		The "hydrophobic effect" of hydrophobic solutes in water (such as non-polar gasses) is primarily a consequence of changes in the clustering in the surrounding water rather than water-solute interactions.
		It is the incompatibility between the LDW and the hydrophobic surface that drives the structure formation.
		The hydrophobic effect decreases with increased pressure (or density) as it is dependent on the presence of tetrahedrally-placed water molecules (as in LDW), which reduce in number under the distorting influence of pressure [626].
	www.lsbu.ac.uk /water/phobic.html (1646 words)

	Theory of the Hydrophobic Effect. (Site not responding. Last check: 2007-11-04)
		Hydrophobic effects are the driving force for the formation of membranes and micelles from aqueous solution.
		Hydrophobic effects are commonly believed to play a similar role in the folding of globular proteins, although proteins are very much more complex systems.
		However, because hydrophobic effects are an entropic manifestation of solvation by a remarkably complex liquid (water!), construction of a valid molecular scale description of hydrophobic interactions has proved to be very difficult.
	exobiology.nasa.gov /ssx/biomod/andrew990830/hydrophobic/hydrophobic.html (337 words)

	Hydrophobic
		Hydrophobic molecules are also called lipophilic because they will dissolve in oils and other lipids.
		In a hydrophobic interaction, although it seems that the hydrophobic molecules are rejecting water, what's actually happening is that water is rejecting the hydrophobic molecules in favour of bonding to itself.
		Hydrophobic molecules then tend to cluster together, though they're not attracted to each other, because according to thermodynamics, large numbers of like molecules are energetically more favourable than smaller numbers.
	www.iscid.org /encyclopedia/Hydrophobic (192 words)

	The Hydrophobic Effect
		The hydrophobic effect is considered to be the major driving force for the folding of globular proteins.
		The decrease in the strength of the hydrophobic effect with decreasing temperatures is probably the major cause of cold-denaturation in proteins.
		The model compound studies predict that the hydrophobic effect of exposing one buried methylene group to bulk water is 0.8 kcal/mol (in Pace, 1995).
	www.cryst.bbk.ac.uk /PPS2/projects/day/TDayDiss/HydrophobicEffect.html (800 words)

	Hydrophobic effect biography .ms (Site not responding. Last check: 2007-11-04)
		The hydrophobic effect is usually described in the context of protein folding, protein-protein interactions, nucleic acid structure, and protein-small molecule interactions.
		The energetics of DNA structure assembly were determined by Eric Kool to be mostly caused by the hydrophobic effect, as opposed to Watson-crick base pairing.
		The hydrophobic effect can be nullified to a certain extent by lowering the temperature of the solution to near zero degrees; at such temperatures, water prefers to be in an ordered structure and the order generated by hydrophobic patches is no longer as energetically unfavorable.
	www.biography.ms /Hydrophobic_effect.html (204 words)

	Long-Range Hydrophobic Interactions (Site not responding. Last check: 2007-11-04)
		Hydrophobic interactions are ubiquitous in nature, and are linked intimately to processes such as the folding of proteins and the binding of enzymes to substrates.
		The most commonly discussed hydrophobic interaction is the "hydrophobic effect." In this phenomenon, the unfavorable entropy resulting from the ordering of water around a hydrophobic solute provides a driving force for solutes to aggregate and thereby reduce the hydrophobic surface area available to the solvent.
		Aqueous solubility is known to be a poor predictor of hydrophobicity, so in collaboration with Udayan Mohanty we have developed a first-principles theory to describe the effect of gas on the interactions between bubbles.
	chemserv.bc.edu /Department/Faculty/fourkas/Bubbles.html (662 words)

	Methane-induced hemolysis human Red Blood Cells
		The effect of sample volume was measured to determine the effect of diffusion time of gases through the aqueous solutions in the absence of a facility to stir the specimens in the pressure cell.
		The effect of methane and nitrogen on erythrocyte survival was measured as a function of the pressure of the applied gas.
		Effect of methane and nitrogen on the degree of hemolysis of erythrocyte suspension.
	www.sb.fsu.edu /~soma/Publications/bcjpaper.html (4665 words)

	SURFACE SCIENCE: ON HYDROPHOBIC ASSEMBLY AT INTERFACES
		Although the relative positions of small hydrophobic molecules in water are correlated, these correlation effects are modest and similar to what is seen for most small molecules in most homogeneous liquids.
		Hydrophobic patches have also been observed in native protein structures at sites where two a helices interact, and there is good evidence that hydrophobic clusters of this kind can guide the folding process.
		1) The hydrophobic interaction, the tendency for nonpolar molecules to aggregate in solution, is a major driving force in biology, a force that stabilizes biological structures ranging from native conformations of proteins to cellular membranes, and the origin of this effect has been the topic of much investigation, both experimental and theoretical.
	scienceweek.com /2005/sw051125-6.htm (1447 words)

	Chandler Group - The Two Faces of Water
		It is this energetic effect, the loss of hydrogen bonding, that leads to the segregation of oil from water.
		Adjacent to the hydrophobic surface, the lower left portion of the figure, the density is depleted relative to bulk water.
		The depletion is a manifestation of the drying transition that lies at the heart of large length scale hydrophobicity.
	gold.cchem.berkeley.edu /research_twofaces.html (1470 words)

	Self assembly systems
		The combination of hydrophobic and hydrophilic groups in the same molecule is a common theme in phosopholipids and detergents and an important structural feature determining their assembly into either membranes or micelles, respectively.
		The hydrophobic effect is mostly an entropic effect because the water molecules that would surround the hydrocarbons could do so only by decreasing the entropy of the water shell structure (more ordered).
		The hydrophobic part of the protein is embedded in the hydrocarbon part of the lipid membrane, and hydrophilic surfaces of the protein are in contact with the lipid headgroups and the water surrounding the two sides of the membrane.
	www.whatislife.com /reader/selfassembly/selfassembly.html (1367 words)

	QSG
		The hydrophobic effect plays a central role in processes spanning numerous scientific and technological disciplines, from protein folding to the formation of natural gas hydrates in oil and gas pipelines.
		Considerable experimental research has focused on understanding the thermodynamic properties that govern the hydrophobic effect, particularly since the discovery that thermal features of protein denaturization resemble those for transferring small non-polar molecules to water.
		New nanotech devices will have hydrophobic regions for which an accurate description of the water at the interface will be critical, for example in a nanotube sensing device as shown here.
	www-phys.llnl.gov /Research/qsg-090205/hydrophobicSolutes.html (942 words)

	RedOrbit - Science - Osmolyte Trimethylamine-N-Oxide Does Not Affect the Strength of Hydrophobic Interactions: Origin ... (Site not responding. Last check: 2007-11-04)
		The precise balance of the effects of hydrophobic and hydrophilic segments of the molecule appears to explain the virtual noneffect of TMAO on the strength of hydrophobic interactions.
		Effect of TWlAO on the conformational equilibria of a hydrophobic polymer
		At the molecular level, the neutrality of TMAO toward hydrophobic interactions is manifested in the lack of strong preferential binding or depletion of TMAO in the vicinity of hydrophobic solutes.
	www.redorbit.com /news/display?id=211959&source=r_science (5062 words)

	[No title]
		We conclude that, although the types of interactions are similar between protein-protein interfaces and single-chain proteins overall, the contribution of the hydrophobic effect to protein-protein associations is not as strong as to protein folding.
		The hydrophobic folding units at the interfaces of two-state complexes suggest that the cooperative nature of the two-chain protein folding is the outcome of the hydrophobic effect, similar to its being the driving force in a single-chain folding.
		The growing interest in the hydrophobic effect arises from its importance in the protein folding process, and a semiempirical simulation of the free energy of solvation is proposed.
	sosnick.uchicago.edu /papers/Papers_to_get.txt (2570 words)

	Hydrophobic effect - Wikipedia, the free encyclopedia
		The energetics of DNA tertiary structure assembly were determined by Eric Kool to be mostly caused by the hydrophobic effect, as opposed to Watson-crick base pairing.
		The hydrophobic effect can be nullified to a certain extent by lowering the temperature of the solution to near zero degrees Celsius; at such temperatures, water "prefers" to be in an ordered structure and the order generated by hydrophobic patches is no longer as energetically unfavorable.
		The transfer free energy of nonpolar molecule from nonpolar solvent to aqueous solvent is often used to quantify the hydrophobic effect.
	en.wikipedia.org /wiki/Hydrophobic_effect (467 words)

	Effect of Hydrophobic Surfactant Peptides SP-B and SP-C on Binary Phospholipid Monolayers. I. Fluorescence and ...
		Effect of Hydrophobic Surfactant Peptides SP-B and SP-C on Binary Phospholipid Monolayers.
		The effect of the synthetic SP-B peptide fragment on PA was to
		Effect of hydrophobic protein SP-C on structure and dilational properties of the model monolayers of pulmonary surfactant.
	www.biophysj.org /cgi/content/full/77/2/903 (6645 words)

	Computing the hydrophobic energies (Site not responding. Last check: 2007-11-04)
		One may sometimes find ordered water in a completely hydrophobic region, but this is by no means common and the ordering which is thought to be responsible for the hydrophobic effect cannot, in general, be observed on an X-ray time scale.
		The entropic contribution is assumed to be constant at an undisturbed hydrophobic surface.
		WENT is therefore responsible for much of the so-called hydrophobic effect, but may not be wholly responsible because the induction/dispersion interaction energy (ELJ) between the hydrophobic molecules must not be forgotten.
	www.moldiscovery.com /docs/grid/c43.html (2627 words)

	BioMed Central \| Full text \| Mutation of exposed hydrophobic amino acids to arginine to increase protein stability
		Hydrophobic residues were chosen by visual examination of the structure and arginine was chosen because the guanidinium group is the most polar of all the common amino-acid residues found in proteins.
		This increase of folding efficiency can be attributed to the reverse hydrophobic effect: if a hydrophobic residue is less exposed to the solvent in the denatured form than in the native form, it will oppose folding [18].
		The effect of mutations on stability was homogeneous, a mutation either destabilizes or stabilizes the protein since we never found a mutation which significantly stabilizes the protein for one agent and significantly destabilizes it for another.
	www.biomedcentral.com /1471-2091/5/9 (2590 words)

	Untitled Document (Site not responding. Last check: 2007-11-04)
		The hydrophobic interaction, the tendency for nonpolar molecules to aggregate in solution, is a major driving force in biology.
		In a direct approach to the physical basis of the hydrophobic effect, nanosecond molecular dynamics simulations were performed on increasing numbers of hydrocarbon solute molecules in water-filled boxes of different sizes.
		Ours is the first direct calculation, to our knowledge, of the hydrophobic interaction from molecular dynamics simulations; the excellent qualitative and quantitative agreement with experiment proves that simple van der Waals interactions and atomic point-charge electrostatics account for the most important driving force in biology.
	tsailab.tamu.edu /hydrophobic.htm (226 words)

	Structural Changes and Interactions Involved in the Ca2+-Triggered Stabilization of the Cell-Bound Cell Envelope ...
		Effect of temperature and pH on the activity of the Ca-free and Ca-loaded CEP.
		Effect of the concentration of different neutral salts on the activity of the Ca-free and Ca-loaded CEP at pH 6.5 and 25°C. Activities are plotted as percentages of the activity of the Ca-free CEP at 10 mM CaCl
		of a hydrophobic effect stabilizes the Ca-free CEP and that, on
	aem.asm.org /cgi/content/full/66/5/2021 (4779 words)

	Pin Tool Data
		Effect of concentration of DNA and BSA on volume transferred with uncoated and hydrophobic coated slot pins - liquid to liquid.
		Effect of concentration of DNA and BSA on volume transferred with uncoated and hydrophobic coated slot pins - liquid to dry plate.
		Hydrophobic coated and uncoated, Solid and Slot Pins were dipped into variable volumes of FITC in 100% DMSO or 0.1M Tris Buffer in 96 well source plates (25, 50, 100, and 200 ul).
	www.vp-scientific.com /pin_data.htm (918 words)

	NON-COVALENT FORCES
		It is reasonably clear that the hydrophobic effect is a consequence of the special properties of liquid water, most probably a combination of the strong hydrogen bonding and the small size of water.
		It is now clear that the hydrophobic effect is not just an entropic effect as was postulated for many years, but has both entropic and enthalpic contributions which vary dramatically with temperature.
		The underlying basis of the hydrophobic interaction is the lack of strong favorable interactions between polar water molecules and non-polar molecules.
	www.chemistry.ucsc.edu /~fink/200lecture/3-97.htm (1232 words)

	Determination of optimal Chebyshev-expanded hydrophobic discrimination function for globular proteins
		The investigation of this power, which would illuminate the role of the hydrophobic effect in proteins, is important and interesting.
		During the folding process, residues with charged and polar side chains remain exposed to the solvent, and those with hydrophobic side chains segregate into the interior of a globular protein [17, 18].
		Series of experiments [19–22] as well as theoretical studies [16, 23–27] show evidence that the nonspecific interaction and placement of hydrophobic residues is a more critical determinant of protein structure than local sequence-dependent interactions.
	www.research.ibm.com /journal/rd/453/fain.html (3467 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		The apparent attraction between small hydrophobes is largely an entropic effect, due to the partitioning of the free volume available to the solvent.
		In the case of inert solutes the solvent contribution to the long-range attraction between hydrophobic molecules is virtually non-existent.
		Influence of the Hydrophobic Effect and Solvent Exposed Area'', A.
	www.lecb.ncifcrf.gov /~wallqvis/hydrophobicity.html (392 words)

	The hydrophobic interaction (Site not responding. Last check: 2007-11-04)
		The hydrophobic character of a molecule is extremely important in pharmaceutical research.
		The hydrophobic character of a group is measured by a distribution experiment between n-octanol and water.
		The hydrophobic character of a molecule can be calculated from the sum of the hydrophobic character of the individual groups.
	online-media.uni-marburg.de /chemie/bioorganic/vorlesung1/k1e-16.html (418 words)

	1st set of Recitation Notes
		Hydrophobic {water fearing} Describes molecules or functional groups that are poorly soluble in water {the standard polar solvent}.
		The hydrophobic effect is the result of the interaction of the nonpolar functional group with other nonpolar functional groups and with the solvent (water).
		The hydrophobic effect decreases the entropy of the system, proportional to the surface area of the nonpolar region exposed.
	www.courses.rochester.edu /platt/BIO150/Recitation1N.html (1632 words)

	Effect of Hydrophobic Surfactant Proteins SP-B and SP-C on Binary Phospholipid Monolayers: II. Infrared External ...
		Effect of Hydrophobic Surfactant Proteins SP-B and SP-C on Binary Phospholipid Monolayers: II.
		analogous to the effect that divalent cations in the subphase
		Effect of the hydrophobic peptide SP-C on binary phospholipid monolayers.
	www.biophysj.org /cgi/content/full/84/1/326 (7776 words)

	[No title] (Site not responding. Last check: 2007-11-04)
		Adding a hydrophobic residue forces the water molecules to form some sort of ordered arrangement, and this comes at a cost (it's energetically unfavorable to impose order on a system), and so it is energetically less favorable to surround two hydrophobic molecules because that would require more ordering of water around them.
		This is why when the ionic strength increases, the hydrophobic effect increases - there is even more "pressure" on those molecules to stick together and reduce the total surface area of their combined bulk that water and the salts will have to surround.
		Since we know what drives the hydrophobic effect, we can deduce that chaotropic salts interfere with the hydrogen bonds, removing the "pressure" on the hydrophobic residues to stick together because water no longer has to be ordered around it to maintain hydrogen bonds.
	staff.washington.edu /dmwenzel/EXTRAPROBLEMSANSWERS.doc (1432 words)

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