Affinity for hydrophobic

Torres, E. Baeza, A., and Vazquez-Duhalt, R., Chemical modification of heme group improves hemoglobin affinity for hydrophobic substrates in organic media. Journal of Molecular Catalysis, B-Enzymatic, 2002. 19 pp. 437—441. 

Since adsorption at a mineral surface is a replacement process, we would expect mineral surfaces with weak affinity for water to have the strongest affinity for hydrophobic solutes. Infrared spectroscopy shows that siloxane surfaces on clays with little isomorphic substitution form weaker hydrogen bonds than water forms with itself (64), which corresponds to one of the definitions of a hydrophobic surface offered by Texter et al. (65) Therefore,... 

Chromosorb T shows the direct correlation of capacity with the oc-tanol-water partition coefficient expected of hydrophobic adsorbents (6). Its overall affinity for hydrophobic water contaminants is similar to that of Amberlite XAD-8 (Rohm and Haas), but it has additional affinity for humic acid and for water-soluble, cationic, aromatic dyes. Chromosorb T is more easily cleaned than the XAD resins, and it is more inert, contributing essentially no contaminants to eluates. Table IV illustrates the adsorption and recovery of a series of hydrophobic test solutes at 50 ppb in 8 L of synthetic hard water on a 50-mL bed of Chromosorb T. 

The lower frequency of lactic acidosis during treatment with metformin compared with other biguanides may be caused by its short non-polar hydrophobic side chains substituted with two CH3 groups. This has a lower affinity for hydrophobic structures, such as phospholipids in mitochondrial and cellular membranes, than the longer monosubstituted side-chains of the other biguanides (64). 

The stabilizing function of macromolecular surfactants in solid-liquid systems is exercised through protective colloid action. To be effective, they must have a strong solution affinity for hydrophobic and hydrophilic entities. In liquid-liquid systems, surfactants are more accurately called emulsifiers. The same stabilizing function is exercised in gas-liquid disperse systems where the surfactants are called foam stabilizers. 

Recent advances in this technology include the use of 2 1 clays converted to hydrophobic forms through the introduction of surfactants in the interlayer. For example, Boyd et al. (1991) introduced cationic chain surfactants into 2 1 clay minerals. Such clays were demonstrated to have high affinity for hydrophobic organic chemicals. Additionally, polyethylene oxides (PEOs) have been intercalated into aluminum-pillared montmorillonite (Montarges et al., 1995). Because PEOs have a... 

Disperse dyes are relatively small molecules, with very low water solubility, which possess a high affinity for hydrophobic fibres such as cellulose acetate, polyester or blends thereof. The dyes are applied by transfer printing or high temperature steam fixation. Azo and anthraquinone dyes constitute the major portion of disperse dyes. 

In any particular system, some limited subset of these interactions is likely to dominate overall sorption behavior. In saturated subsurface systems, for example, most natural solid phases have only a weak affinity for hydrophobic organic compounds. It is frequently presumed for such systems that the characterization of one major sorption reaction, such as that between organic contaminants and natural organic matter associated with soils, sufficiently characterizes the overall process. Such an approach may be problematic for circumstances in which limited characterizations developed from one set of observations are extended to different system conditions, including different contaminant concentration ranges. 

Octadecyl-Sepabeads particles do not swell when transferred from a buffered aqueous solution to an anhydrous medium, and they can be used in all reaction media [12]. The adsorption of enzymes in Octadecyl-Sepabeads was first proposed by Palomo et al. [12] for the immobilization of lipases. The idea behind this method was to take advantage of the enzyme affinity for hydrophobic interfaces as a strategy of immobilization. 

The polymer Nafion is an ionomer with < 15% ionizable sulfonate groups per monomer unit. It has a partly hydro-phobic character and a very high affinity for hydrophobic cations [47,48]. Nafion films feature segregation of hydro-phobic and hydrophillic regions, and can be considered as insoluble polymeric surfactants . 

Loss ofinsulin by adsorption, due to its affinity for various compounds and materials, is a common phenomenon, especially at low concentrations ofinsulin, i.e., less than 1 lU/ml, and large surface areas. Insulin has binding affinity for hydrophobic (Hirsch et al, 1981) as well as hydrophilic surfaces (Mitrano and Newton, 1982), although more insulin is adsorbed onto... 

Polyelectrolyte films can serve as suitable hosts for proteins, which are themselves polyelectrolytes. Nation (Figure 11), a perfluosulphonate ionomer with less than 15% ionizable sulfonate groups per monomer, has partly hydrophobic and partly anionic character, resulting in high affinity for hydrophobic cations [64-66]. 

The CYPs may be involved in many DDIs because of their affinity for hydrophobic molecules of varying sizes. It is widely believed that an understanding of DDIs at the molecular level may lead to the development of more effective and safer therapeutics. In the absence of a freely available crystal structure for any of the human CYPs, there is an obvious need to build computational models in an attempt to predict drug metabolism and... 

Considering several criteria and a weighting, which need not be explained here in detail, the following phases can be denoted as some of the most polar types. These phases also show a low affinity for hydrophobic analytes and an enhanced selectivity for strong ionic pairs of analytes in buffered eluents. 

The modification of enzyme by attaching ions or molecules is a suitable way for providing it with useful fimctions. For example, the use of modifiers such as polyethylene glycol (PEG) (7,2) and synthetic lipids (i) enhances the affinity for hydrophobic environments. PEG-modified enzymes are soluble and active in various organic solvents as well as aqueous solutions (7,2). Lipid-modified enzymes are insoluble in aqueous solutions, but show catal c activities in both aqueous and organic media (i). These unique properties lead us to apply PEG- and lipid-modified enzymes in the construction of enzyme electrodes. 

Soots or lampblack or carbon black are generally hydrophobic and accompanied by fatty substances adsorbed onto their surface. Their fineness and their affinity for hydrophobic synthetic surfaces make them difficult to remove from cotton as well as from synthetics. Because of the organophilic nature of their surfaces, very little electrostatic action is possible. Strongly ionic media tend to flocculate them rather than disperse them, which distinguishes them greatly from the more usual particle soils. 

Continuous extraction by pervaporation through a polydimethylsUoxane membrane (with higher affinity for hydrophobic molecules than for water) was demonstrated for B. adusta CBS 595.79 cultures, concentrating benzaldehyde up to 90 times [99]. 

PHA depolymerases have high affinity for hydrophobic materials and hence their purification protocols include hydrophobic interaction chromatography. 

From the hydrolases toolbox, probably lipases have been the most demanding catalysts for synthetic application. Their natural funchon involves the hydrolysis of triacylglycerol ester bonds, compoimds that are poorly soluble in water. Thus, the reaction usually occurs in an organic-aqueous interface. This phenomenon involving the conformational change of the selected lipase is called interfacial achvahon [35], and it provides an inherent affinity for hydrophobic media to the enzyme. 

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