Carbohydrates nonpolar interactions

Isolated compounds include alkyl, aromatic, ahcyclic, or functional groups with significant hydrocarbon structure. All isolates have a potential for nonpolar interaction (except inorganic ions and compounds with polar groups, e.g., carbohydrates). Because of this fact, the nonpolar interactions are nonselective and allow the extraction of... 

Lipids can best be defined as biomolecules which are soluble to a great extent in nonpolar solvents. In contrast to carbohydrates, proteins and nucleic acids, lipids do not have polymeric forms. By virtue of their hydrophobic nature they aggregate into large complexes, held together to a significant degree by nonpolar interactions. 

The precise chemical interactions between an adhesin and its receptor are also important. For example, direct- and water-mediated hydrogen bonds are the most important interactions within the carbohydrate-recognition domain in carbohydrate-binding adhesins on the host cell surface (Weis and Drickamer, 1996). Nonpolar van der Waals interactions and hydrophobic "stacking of the receptor oligosaccharide rings with aromatic amino acid side chains of the bacterial adhesin protein also contribute to oligosaccharide-protein interactions. X-ray structural... 

During the extraction process three types of interactions are usually disrupted, these are van der Waals forces in lipid-lipid, lipid-protein, and liquid-carbohydrate complexes electrostatic and hydrogen bonding interactions between lipids andproteins andcovalent bonding between lipids, carbohydrates, and proteins (Roby t and White, 1987). The solvent of choice depends on the type of lipid and the interactions to be disrupted. Thus, neutral lipids may be extracted with nonpolar solvents, while phospholipids and glycolipids are extracted with more polar solvent mixtures (Shahidi and Wanasundara, 1998). 

Recently, Slattery and Evard (171) proposed a model for the formation and structure of casein micelles from studies devoted to association products of the purified caseins. They proposed that the micelle is composed of polymer subunits, each 20 nm in diameter. In the micellar subunits the nonpolar portion of each monomer is oriented radially inward, whereas the charged acidic peptides of the Ca2+-sensitive caseins and the hydrophilic carbohydrate-containing portion of K-casein are near the surface. Asymmetric distribution of K-casein in a micelle subunit results in hydrophilic and hydrophobic areas on the subunit surface. In this situation, aggregation through hydrophobic interaction forms a porous micelle (Figure 10). Micelle growth is limited by the eventual concentration, at the micelle surface, of subunits rich in K-casein. 

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