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Chemical Reaction: An Update on Water
By: Steve Herman
Posted: October 26, 2006, from the October 2006 issue of GCI Magazine.
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Proteins are long chains with both hydrophilic and hydrophobic sections. Their three-dimensional structure is determined by how the chains fold, with the hydrophilic parts on the surface, and the hydrophobic parts in the interior. Three types of water must be built into a computer model of protein interaction. Ordered waters surround and strongly interact with the molecule, bulk waters are further away, and some water is buried within the protein.
Of particular interest is the interaction of water with the deep grooves on the surfaces of enzymes. Water is easily displaced from the grooves by ligands, which may explain why the grooves are frequently the active sites. The arrangement of water molecules in the groove often corresponds to the geometry of the ligand, which is a valuable clue for rational drug design.
Water has been a mainstay of cosmetics, and while you have just seen the importance of water for the structure of protein, now The New York Times warns,3 “Dangerous When Wet … The worst thing you can do for you skin may well be washing it with water.” It seems water is a lethal broth of heavy metals: iron, copper, magnesium, zinc and lead. They interact with free radicals and attack collagen. Calcium is not a heavy metal, but creates hard water that leads to dull, dry skin and hair.
MD Skincare4 has attacked the metals with Hydra-Pure Moisture Cream, basing its value on the presence of chelators. Clarins5 also is combating the wash-and-rinse ritual with its Water Purify: “The feeling of cleansing with water without water.” There now is a notable trend toward anhydrous products and cleaning without water for both skin and hair.
So far the garden variety of water has been discussed, but chemistry has designer water also, and it finds its way into cosmetics. Deuterium is hydrogen where each nucleus has a neutron as well as a proton. This makes it twice as heavy as normal hydrogen. Heavy water is water in which both the hydrogens are replaced by deuterium.