Native precipitation

If the biological activity of the protein needs to be preserved, it should be precipitated at low temperatures with ammonium sulfate or polyethylene glycol (PEG) or organic solvents (acetone, ethanol, or methanol). 

Problems Ammonium sulfate and PEG do not precipitate the protein or do so incompletely from diluted solutions, and the precipitation with ammonium sulfate results in large amounts of often undesirable ions. The organic solvents denature some proteins even at low temperatures. 

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The nucleation of crystalline calcium phosphates in aqueous solutions is occasionally preceded by the formation of amorphous calcium phosphate (ACP) [1-6]. Abbona and Baronnet [7], Brecevic et al. [8], and Christoffersen et al. [9] were among the first to report such early-forming i.e., within the first few minutes of synthesis) ACP nanoparticles by using electron microscopy. If such ACP nanoparticles were not intentionally stabilized by adding Mg pyrophosphate or carbonate ions [10] to tbe synthesis media, then they transform into crystalline octacalcium phosphate (OCP, Ca3(HP04)2(P04)4-5H20) or non-stoichiometiic apatitic calcium phosphate with an increase in aging time, even in their native precipitation solutions [11-19]. 

Treatment of the native, precipitated LHC with low concentration of trypsin produced no alteration in the polypeptide pattern of the LHC. Treatment of the native solubilized complex with the same amounts of trypsin led to the disappearance of the 27 kO band on SOS gels, while the 25 KD band remained visible. 

The significance of phenoxy anions is well recognized in the isolation of kraft and other water-insoluble technical lignins by acid precipitation. The ioniza tion of phenoHc hydroxyl groups coupled with the reduction of molecular size renders native lignin soluble in the aqueous pulping solution, thus enabling its separation from the polysaccharide components of wood. 

Asphalt, prepared from petroleum, often resembles native asphalt. When asphalt is produced by distillation, the product is called residual, or straight-mn, asphalt. However, if the asphalt is prepared by solvent extraction of residua or by light hydrocarbon (propane) precipitation, or if it is blown or otherwise treated, the name should be modified accordingly to qualify the product, eg, propane asphalt. 

Humans have used dyes to create color since the dawn of history. Until the mid-nineteenth century, all dyes were of natural origin. Many came from plants, such as indigo, a dark blue dye that was extracted from the leaves of a native East Indian plant. In 1856, the young English chemist William Perkin stumbled upon the first synthetic dye. Perkin was trying to synthesize quinine, a valuable antimalaria dmg. None of his experiments met with success. As he was about to discard the residue from yet another failed reaction, Perkin noticed that it was colored with a purple tinge. He washed the residue with hot alcohol and obtained a purple solution from which strikingly beautiful purple crystals precipitated. Perkin had no idea what the substance was or what reactions had created it, but he immediately saw its potential as a new dye. 

Salting-out salts (Na2S04, NaCl, MgS04) Surface tension increase Weak binding Stabilize globular proteins and precipitants of native and denatured proteins... 

III PEG MPD Steric exclusion Repulsion from charges To hydrophobic regions Good precipitants stabilizers of native structure at low temp., unfolded structure at high temp. stabilizers and solubilizers of hydrophobic domains in proteins... 

Because of the water-holding properties of soils and the fact that most precipitation returns to the atmosphere via ET, it is possible to devise a landfill cover to meet remediation requirements, and yet contain no barrier layer. The ET cover consists of a layer of soil covered by native grasses it contains no barrier or impermeable layers. The ET cover uses two natural processes to control infiltration (1) soil provides a water reservoir and (2) natural evaporation from the soil plus plant transpiration (ET) empties the soil water reservoir.32-38 The ET cover is an inexpensive, practical, and easily maintained biological system that will remain effective during extended periods of time—perhaps centuries—at low cost. 

The migration of iron mineral fines, primarily hematite and magnetite, is a common occurrence in portions of the Appalachian Basin. The phenomenon often occurs after well stimulation and can result in the continuing production of iron mineral fines which pose a significant disposal problem. The migration of iron mineral fines through propped fractures can substantially reduce the fracture flow capacity. Many of these are mineral fines are native to the formation and are not formed by precipitation of acid-soluble iron salts present in injection waters during or after acidi-... 

It should be noted that complete blocking of all amines on proteins with sulfo-NHS acetate may cause precipitation or loss of native structure and function. The acetate modifications... 

Fig. 6. i Oak Native Lignin after four precipitations 2 Oak Native Lignin aftereight precipitations 3 and 4 White Scots Pine Native Lignin. 

Raw silk was dissolved in hexafluoro-iso-propanol (HFIP) [17, 33]. A typical working concentration for spinning was 2.5% (w/v) silk fibroin in HFIP. The spinning solution was pressed through a small needle (0 80-250 pm) into a precipitation bath (methanol for Bombyx mori silk proteins and acetone for Nephila clavipes silk proteins) and the silk solution immediately precipitated as a fiber. The best performing fibers approached the maximum strength measured for native fibers of Bombyx mori, but did not achieve the mechanical properties of natural spider silk. 

Native factor VIII is traditionally purified from blood donations first screened for evidence of the presence of viruses such as hepatitis B and HIV. A variety of fractionation procedures (initially mainly precipitation procedures) have been used to produce a factor VIII product. The final product is filter-sterilized and filled into its finished product containers. The product is then freeze-dried and the containers are subsequently sealed under vacuum, or are flushed with an inert gas (e.g. N2) before sealing. No preservative is added. The freeze-dried product is then stored below 8 °C until shortly before its use. 

DASPE-TFPB), respectively. The obtained solid precipitates were brightly emissive whereas that of the native DASPE-I were almost nonemissive (Fig. 7a the photo is taken under normal illumination and UV-light irradiation). This indicates that, in the solid of the ion-pair species between DASPE+ and TPB (or TFPB ), concentration quenching is effectively suppressed, and more importantly, these ion-pair complexes can generate fluorescent... 

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