Hydrophobic interactions micelle analog

The improved DNA binding and condensation provided by amino acids such as tryptophan suggests that the inclusion of hydrophobic interactions within DNA complexes may be beneficial. Peptides with moities that provide cooperative hydrophobic behavior of alkyl chains of cationic lipids would improve the stability of the peptide-based DNA delivery systems. Two general classes of lipopeptide analogs of Tyr-Lys-Ala-Lysn-Trp-Lys peptides have been prepared by including a hydrophobic anchor. The general structures are N, N-dialkyl-Gly-Tyr-Lys-Ala-Lysn-Trp-Lys and Na,Ne-diacyl-Lys-Lysn-Trp-Lys. These peptides differ from the parent structures in that they self-associate to form micelles in aqueous solutions. The inclusion of dialkyl or diacyl chains in the cationic peptides improves the peptide ability to bind DNA and reduces aggregation of the complexes in ionic media. 

X HE USE OF HYDROPHOBIC INTERACTIONS to produce associative thickeners has increased markedly over the past 10 years in such diverse areas as surface coatings and enhanced oil recovery. The desired thickening properties are produced by relatively low molecular weight polymers that are reversibly cross-linked by pendant hydrophobic moieties to give a three-dimensional network. To maintain solubility, the number of hydrophobes per soluble molecule is low, and the chain length is typical of that used in surfactants (i.e., Cs-Cie). In solution, the hydrophobes appear to associate in an analogous fashion to micellization, in that, in the absence of surfactants. 

In lyophobic colloidal systems, the addition of sufficient salt generally brings about flocculation. An analogy between colloidal flocculation and the nonbinding-binding transition has been drawn [48]. The counterion layer around the micelle is narrowed in a solution containing higher concentration of ions, which facilitates the approximation of the solute to the micellar assembly. Hydrophobic interactions between the solute and the nonpolar core of the micelle can then be established. 

Finally, self-assembly from ionic interaction, hydrophobic interactions, and hydrogen bonding used widely by nature to build composites is receiving very wide attention in academia and industry to build new composites. Simple analogs already exist as in micelles, vesicles, rheology modifiers, and thickeners. 

A mechanistic model has been proposed for PPIase catalysis in which a twisted peptide bond, a structure involving substrate strain, is stabilized by noncovalent interaction with the enzyme [156], However, catalytic antibodies generated to transition state analogs containing twisted carbonyl moieties do not show a PPIase-like catalytic efficiency [157,158], Consequently, small detergent micelles and phosphatidylcholine membranes are able to catalyze CTI of typical PPIase substrates in a manner reminiscent of that observed for catalytic antibodies [159]. Apparently, sequestration of hydrophobic substrates within the enzyme may account for both a small portion of the catalytic power of FKBP and the acceleration of CTI by catalytic antibodies. Despite overall amino acid sequence dissimilarity the structural features making up the active sites of prototypic enzymes such as Cypl8 and ParlO proved to be similar (Fig. 10.6). 

In this variant of CZE, adapted to the separation of neutral or polar molecules, a cationic or anionic surfactant, e.g. sodium dodecylsulfate, is added in excess to the background electrolyte to form charged micelles. These small spherical species, immiscible in the solution, form a pseudo-stationary phase analogous to the stationary phase in HPLC. They trap neutral compounds efficiently through hydrophilic/hydrophobic affinity interactions (Figure 8.9). Neutral molecules as well as ionic species can then be conveniently separated as a direct result of their solubilization within the micelles. 

Dendrimer offers excellent host-guest property, which leads to the noncovalent interactions for the encapsnlation of drug molecules (Figure 15.4). The core is hydrophobic, while the shell is hydrophilic in dendrimers. This analogous micelle-like behavior makes it a promising carrier for drugs and... 

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