Principle
There are hydrophobic amino acids and hydrophilic amino acids in protein molecules. After protein folding in aqueous solution, hydrophobic amino acids usually form protected hydrophobic areas while hydrophilic amino acids interact with the molecules of solvation and allow proteins to form hydrogen bonds with the surrounding water molecules. If enough of the protein surface is hydrophilic, the protein can be dissolved in water.
When the salt concentration is increased, some of the water molecules are attracted by the salt ions, which decreases the number of water molecules available to interact with the charged part of the protein. As a result of the increased demand for solvent molecules, the protein-protein interactions are stronger than the solvent-solute interactions; the protein molecules coagulate by forming hydrophobic interactions with each other. This process is known as salting out.
Soaps are easily precipitated by concentrated salt solution, the metal ion in the salt reacts with the fatty acids forming back the soap and glycerol.
Read more about this topic: Salting Out
Famous quotes containing the word principle:
“The principle of asceticism never was, nor ever can be, consistently pursued by any living creature. Let but one tenth part of the inhabitants of the earth pursue it consistently, and in a day’s time they will have turned it into a Hell.”
—Jeremy Bentham (1748–1832)
“The principle of majority rule is the mildest form in which the force of numbers can be exercised. It is a pacific substitute for civil war in which the opposing armies are counted and the victory is awarded to the larger before any blood is shed. Except in the sacred tests of democracy and in the incantations of the orators, we hardly take the trouble to pretend that the rule of the majority is not at bottom a rule of force.”
—Walter Lippmann (1889–1974)
“No habit or quality is more easily acquired than hypocrisy, nor any thing sooner learned than to deny the sentiments of our hearts and the principle we act from: but the seeds of every passion are innate to us, and nobody comes into the world without them.”
—Bernard Mandeville (1670–1733)