Water differential solubilities

Solubility of Polypeptides One method for separating polypeptides makes use of their differential solubilities. The solubility of large polypeptides in water depends upon the relative polarity of their R groups, particularly on the number of ionized groups the more ionized groups there are, the more soluble the polypeptide. Which of each pair of the polypeptides that follow is more soluble at the indicated pH ... 

Classic methods in use to fractionate plant cell wall polysaccharides are mainly based upon the differential solubilities of various cell wall polysaccharide constituents (32). To solubilize pectic polysaccharides, the cell wall material is extracted with water, ammonium oxalate or disodium EDTA. The solubilization of pectic polysaccharides could then be followed by solubilization of hemicelluloses, i.e., polysaccharides rich in D-glucuronic acid 4-0-methyl-D-glucuronic acid, D-xylose and D-glucose residues. The solubilization of hemicellulosic polysaccharides is accomplished by treatment of water, ammonium oxalate or EDTA insoluble material with a strong alkali. 

Black Dyes. Water-soluble black ink jet dyes are selected from disazo, polyazo, metal complex, and sulfur dyes [7], For ink-jet systems using the piezo technology, C.I. Direct Black 19, 35255 [6428-31-5] and DirectBlack 154,303865 [54804-85-2 are used. Food Black 2, 27755 [.2118-39-0] was selected for thermal ink-jet printers due to its thermal stability, but this dye exhibits a poor waterfastness. Replacing the sulfo groups by carboxyl groups gave C.I. DirectBlack 195 (1), which has been introduced in commercial printers and shows much improved waterfastness due to pH-dependant differential solubility [3],... 

Our treatment of basic principles of water-solute relationships involves a bottom-up approach that begins with a basic physical-chemical analysis of how fundamental water solute interactions have set many of the boundary conditions for the evolution of life. We discuss how the properties of macromolecules and micromolecules alike reflect selection based on such fundamental criteria as the differential solubilities of different organic and inorganic solutes in water, and the effects that these solutes in turn have on water structure these are two closely related issues of vast importance in cellular evolution. With these basic features of water-solute interactions established, we will then be in a position to appreciate more fully why regulation of cellular volume and the composition of the internal milieu demands such precision. We then can move upwards on the reductionist ladder to consider the physiological mechanisms that have evolved to enable cells to defend the appropriate solutions conditions that are fit for the functions of macromolecular systems. This multitiered analysis is intended to help provide answers to three primary questions about the evolution and regulation of the internal milieu ... 

The differential solubilities exhibited by biomolecules thus should be appreciated as one of the most important aspects of the effects of water on living systems. Differential solubility is a critical principle in much of biochemical evolution, and it is a principle that is manifested in a number of contexts of adaptation to the environment. This is seen particularly clearly in the evolution of proteins in the face of different chemical and physical conditions. The amino acids selected to construct a particular protein reflect a finely tuned process that results in the generation of an appropriate three-dimensional structure and a correct balance between structural stability and flexibility—a balance termed marginal stability—that is essential for protein function. The marginal stability of the protein will be seen to be the consequence of complementary adaptations in the protein... 

Since reversed-phase separations are based upon differential solubility of the sample in the mobile and stationary phases, it is not essential to use water if solubility limitations exist. Often a blend of two organic solvents which are the strong and weak solvents can and should be used rather than one organic... 

The increasing sophistication in solution chemistry can be measured by Louis Lemery s attempt in 1716 to account for the differential solubility of salts in water.His close scrutiny of the action of water on various salts hints at a mounting concern over the exact function of water in... 

Chemical analyses revealed no specific components as the cause of observed toxicity. Antagonism between sea salt and toxic chemicals is hypothesized to cause differential toxicity at varying salinities, as opposed to differential solubility of the toxicants. Extrapolation of laboratory results indicates that proposed tire reefs should not pose a serious threat to water quality in Chesapeake... 

Retinoids are insoluble in water, but soluble in organic solvents, such as ethanol and dimethylsulfoxide (DMSO), which are the most commoidy used solvents for administration of tRA. Although one always performs control experiments, it is important to be aware of the fact that DMSO acts as a differentiating agent to embryonal carcinoma cell cultures in the same way that tRA does, so perhaps ethanol is a better solvent. The maximum solubility of tRA in DMSO is about 50 mg/mL. 

Problems can arise because of differential solubilities of reactants and products. In a recent example studied in the authors laboratory it was desired to hydrolyse a water insoluble ester bearing another group sensitive to hydrolysis, using aqueous sodium hydroxide (equation 12.11). The desired product (II) could react further losing X (equation 12.12). 

Fr chet and TuUy have used poly(aryl ether) dendrimers, terminated with carbonate end groups as photoresists [99]. The aqueous insoluble carbonate terminated dendrimers were applied as a layer to a substrate. This dendritic layer was exposed subsequently to deep UV radiation or electron beam radiation and then baked to convert the masked areas of the dendritic carbonate coating to the deprotected and water-soluble polyphenoxide dendrimers by decarboxylation of the peripheral groups. The resultant deprotected polyphenoxide dendrimers exhibited differential solubility to the carbonate terminated dendrimers, which was exploited by removal of either the carbonate terminated or hydroxyl terminated dendrimer by washing with protic organic or aqueous solvents, respectively (Figure 8.15). 

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