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Crystallization Adjutant
A crystallization adjutant is a material used to promote crystallization, normally in a context where a material does not crystallize naturally from a pure solution. Additives in Macromolecular Crystallization In macromolecular crystallography, the term additive is used instead of adjutant. An additive can either interact directly with the protein, and become incorporated at a fixed position in the resulting crystal or have a role within the disordered solvent, that in protein crystals constitute roughly 50% of the lattice volume. Polyethylene glycols of various molecular weights and high-ionic strength salts such as ammonium sulfate and sodium citrate that induce protein precipitation when used in high concentrations are classified as precipitants, while certain other salts such as zinc sulfate or calcium sulfate that may cause a protein to precipitate vigorously even when used in small amounts are considered adjutants. Crystallization adjutants are considered additives when they a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystallization
Crystallization is the process by which solid forms, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas. Attributes of the resulting crystal depend largely on factors such as temperature, air pressure, and in the case of liquid crystals, time of fluid evaporation. Crystallization occurs in two major steps. The first is nucleation, the appearance of a crystalline phase from either a supercooled liquid or a supersaturated solvent. The second step is known as crystal growth, which is the increase in the size of particles and leads to a crystal state. An important feature of this step is that loose particles form layers at the crystal's surface and lodge themselves into open inconsistencies such as pores, cracks, etc. The majority of minerals and organic molecules crystallize easily, and the resulting crystals are g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylethanolamine
Phosphatidylethanolamine (PE) is a class of phospholipids found in biological membranes. They are synthesized by the addition of cytidine diphosphate-ethanolamine to diglycerides, releasing cytidine monophosphate. ''S''-Adenosyl methionine can subsequently methylate the amine of phosphatidylethanolamines to yield phosphatidylcholines. Function In cells Phosphatidylethanolamines are found in all living cells, composing 25% of all phospholipids. In human physiology, they are found particularly in nervous tissue such as the white matter of brain, nerves, neural tissue, and in spinal cord, where they make up 45% of all phospholipids. Phosphatidylethanolamines play a role in membrane fusion and in disassembly of the contractile ring during cytokinesis in cell division. Additionally, it is thought that phosphatidylethanolamine regulates membrane curvature. Phosphatidylethanolamine is an important precursor, substrate, or donor in several biological pathways. As a polar head group, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphatidylcholine
Phosphatidylcholines (PC) are a class of phospholipids that incorporate choline as a headgroup. They are a major component of biological membranes and can be easily obtained from a variety of readily available sources, such as egg yolk or soybeans, from which they are mechanically or chemically extracted using hexane. They are also a member of the lecithin group of yellow-brownish fatty substances occurring in animal and plant tissues. Dipalmitoyl phosphatidylcholine (a.k.a. lecithin) is a major component of pulmonary surfactant and is often used in the L/S ratio to calculate fetal lung maturity. While phosphatidylcholines are found in all plant and animal cells, they are absent in the membranes of most bacteria, including ''Escherichia coli''. Purified phosphatidylcholine is produced commercially. The name ''lecithin'' was derived from Greek λέκιθος, ''lekithos'' 'egg yolk' by Theodore Nicolas Gobley, a French chemist and pharmacist of the mid-19th century, who appli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Octyl Glucoside
Octyl glucoside (''n''-octyl-β--glucoside) is a nonionic surfactant frequently used to solubilise integral membrane proteins for studies in biochemistry. Structurally, it is a glycoside derived from glucose and octanol. Like Genapol X-100 and Triton X-100, it is a nonphysiological amphiphile that makes lipid bilayers less "stiff". Applications Octyl glucoside has become one of the most important detergents for purification of membrane proteins because it generally does not denature the protein and can readily be removed from final protein extracts. Above its critical micelle concentration of 0.025 M (~0.7% w/v), it was noted as the best detergent for improving selectivity of immunoprecipitation of phosphotyrosine modified proteins. This detergent has also been shown to rapidly inactivate infective HIV at concentrations above its CMC. The compound gained popularity with researchers following the publication of an improved synthesis in 1978. However, in 1990 the cost remaine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classification Of Surfactants
Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, or dispersants. The word "surfactant" is a blend of ''surface-active agent'', coined . Agents that increase surface tension are "surface active" in the literal sense but are not called surfactants as their effect is opposite to the common meaning. A common example of surface tension increase is salting out: by adding an inorganic salt to an aqueous solution of a weakly polar substance, the substance will precipitate. The substance may itself be a surfactant – this is one of the reasons why many surfactants are ineffective in sea water. Composition and structure Surfactants are usually organic compounds that are amphiphilic, meaning each molecule contains both a hydrophilic "water-seeking" group (the ''head''), and a hydrop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lauryldimethylamine Oxide
Lauryldimethylamine oxide (LDAO), also known as dodecyldimethylamine oxide (DDAO), is an amine oxide based zwitterionic surfactant, with a C12 (dodecyl) alkyl tail. It is one of the most frequently-used surfactants of this type. Like other amine oxide based surfactants it is antimicrobial, being effective against common bacteria such as '' S. aureus'' and ''E. coli'', however it is also non-denaturing and may be used to solubilize proteins. At high concentrations, LDAO forms liquid crystalline phases. Despite having only one polar atom that is able to interact with water – the oxygen atom (the quaternary nitrogen atom is hidden from intermolecular interactions), DDAO is a strongly amphiphilic surfactant: it forms normal micelles and normal liquid crystalline phases. High amphiphilicity of this surfactant can be explained by the fact that it forms not only very strong hydrogen bonds with water: the energy of DDAO – water hydrogen bond is about 50 kJ/mol, but it also has high ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decyl Glucoside
Decyl glucoside is a mild non-ionic surfactant used in cosmetic formularies,Fiume MM, Heldreth B, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler D, Marks JG Jr, Shank RC, Slaga TJ, Snyder PW, Andersen FA. Safety assessment of decyl glucoside and other alkyl glucosides as used in cosmetics. ''Int J Toxicol''. 2013 Sep-Oct;32(5 Suppl):22S-48S. including baby shampoo and in products for individuals with a sensitive skin. Many natural personal care companies use this cleanser because it is plant-derived, biodegradable, and gentle for all hair types. Decyl glucoside was invented by Robert Prairie in 1934. Synthesis Decyl glucoside is produced by the reaction of glucose from corn starch with the fatty alcohol decanol, which is derived from coconut. See also * Lauryl glucoside * Octyl glucoside Octyl glucoside (''n''-octyl-β--glucoside) is a nonionic surfactant frequently used to solubilise integral membrane proteins for studies in biochemistry. Structurally, it is a gly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Detergent
A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more soluble in hard water, because the polar sulfonate (of detergents) is less likely than the polar carboxylate (of soap) to bind to calcium and other ions found in hard water. Definitions The word ''detergent'' is derived from the Latin adjective ''detergens'', from the verb ''detergere'', meaning to wipe or polish off. Detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. However, conventionally, detergent is used to mean synthetic cleaning compounds as opposed to ''soap'' (a salt of the natural fatty acid), even though soap is also a detergent in the true sense. In domestic contexts, the term ''detergent'' refers to household cleaning products such as ''laundry detergent'' or '' dish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipid Polymorphism
Polymorphism in biophysics is the ability of lipids to aggregate in a variety of ways, giving rise to structures of different shapes, known as "phases". This can be in the form of sphere of lipid molecules (micelles), pairs of layers that face one another (lamellar phase, observed in biological systems as a lipid bilayer), a tubular arrangement (hexagonal), or various cubic phases (Fdm, Imm, Iam, Pnm, and Pmm being those discovered so far). More complicated aggregations have also been observed, such as rhombohedral, tetragonal and orthorhombic phases. It forms an important part of current academic research in the fields of membrane biophysics (polymorphism), biochemistry (biological impact) and organic chemistry (synthesis). Determination of the topology of a lipid system is possible by a number of methods, the most reliable of which is x-ray diffraction. This uses a beam of x-rays that are scattered by the sample, giving a diffraction pattern as a set of rings. The ratio of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcohols
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. An important class of alcohols, of which methanol and ethanol are the simplest examples, includes all compounds which conform to the general formula . Simple monoalcohols that are the subject of this article include primary (), secondary () and tertiary () alcohols. The suffix ''-ol'' appears in the IUPAC chemical name of all substances where the hydroxyl group is the functional group with the highest priority. When a higher priority group is present in the compound, the prefix ''hydroxy-'' is used in its IUPAC name. The suffix ''-ol'' in non-IUPAC names (such as paracetamol or cholesterol) also typically indicates that the substance is an alcohol. However, some compound ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipids
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology. Lipids may be broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
