Shell hydrophobic

Since the side chains of consecutive amino acids of a p strand are on opposite sides of the P sheet, every second residue of the p strands contributes to this hydrophobic shell. The other side chains of the P strands point inside the barrel to form a hydrophobic core this core is therefore comprised exclusively of side chains of P-strand residues (Figure 4.3). 

The surface of silica is covered by a layer of acidic silanol and siloxane groups. This highly polar and hydrophilic character of the filler surface results in a low compatibihty with the rather apolar polymer. Besides, highly attractive forces between silica particles result in strong agglomeration forces. The formation of a hydrophobic shell around the silica particle by the sUica-sUane reaction prevents the formation of a filler-filler network by reduction of the specific surface energy [3]. 

Meijer et al [6] reported on inverted unimolecular micelle type dendrimers (Figure 13.4) which have a hydrophilic interior and a hydrophobic shell, synthesized by modifying the end groups of hydrophilic polypropylene imine) dendrimer with alkyl chains. It was shown that these dendrimers could host... 

Vesicle-based capsules The shell is self-assembled into a hydrophobic shell or bilayer surrounded inside and outside by solution. These materials are formed using either small amphiphiles or amphiphilic block copolymer vesicles. 

In different catalytic active CAs, Trp is conserved at position 97, while any one of the hydrophobic amino acids (Phe, Leu, lie, Met) is retained at positions 93 and 95. It has been proposed that these hydrophobic shell residues enhance protein-metal affinity by establishing a metal site environment with a reduced dielectric constant (123). The direct and indirect ligands are invariant in all sequenced and catalytically active a-CAs (103a). 

Figure 7.40 Structure of the spherical lanthanide p-sulfonatocalix[4]arene assembly (a) partial space filling view along the pseudo-fivefold axis. Pyridine N oxide and one calixarene are shown in stick mode. S03 groups line the surface of the sphere, aryl rings define the hydrophobic shell and the polar core comprises 30 water molecules and two Na+ ions, (b) cut away view showing an [Na(H20)6] 2 cluster within the core. (Reprinted with permission from AAAS from [52]).

Gd) [52c]. The crystal structures ofEu(L )3 andEu(L )3 (see Figure 2.10) revealed that three anionic orligands adopt a bidentate coordination mode to produce a six-coordinate metal ion as there are no coordinated solvent molecules. The low coordination number is stabilized by a hydrophobic shell around the central metal ion formed by the 12 o-tolyl groups... 

Figure 2.10 X-ray crystal structure of [Eu(L )3] [52b]. (Reproduced with permission from S. W. Magen-nis, S. Parsons and Z. Pikramenou, Assembly of hydrophobic shells and shields around lanthanides, Chemistry - A European Journal, 2002, 8, 5761-5771. WUey-VCH Verlag GmbH Co. KGaA.)...

Non-covalent thermotropic liquid crystal dendritic systems have been achieved recently by converting the amphiphihc surface of the dendrimers (-NH2) into a hydrophobic shell (alkanoate chains). Tomalia et al. reported on the non-aqueous lyotropic behavior of supramolecular complexes re-... 

ZnSe core QDs of 5 nm in diameter doped with Mn ions were synthesized according to the published procedure and capped with a monolayer of ZnS shell [7]. ZnSe Mn-ZnS QDs were solubilized by the standard procedure of hydrophobic shell replacement by thiols [4]. We used TGA, mercaptoundecanoic acid (MUA) and MPS. Briefly, ca. 5 mg of dry QDs were solubilized in 2 ml of chloroform to which 0.1 ml of 0.1 M methanolic solutions... 

When the crystal structures of ALBP, P2, CRBPII, CRBP, IFABP, and MFB2 were examined, it was found that half of the conserved amino acids are involved in forming a structural backbone, as shown in Table V and Fig. 7. Of the 39 conserved positions, 26 are located within this highly conserved section. The backbones of conserved residues are either internal hydrophobic residues or adjacent solvent-exposed hydrophilic residues. The internal residues appear to form a hydrophobic shell. Although speculative, the crudely alternating pattern of hydrophobic and hydrophilic residues could serve to maintain the hydrophobic residues in the internal position. Five of the hydrophobic core residues also make a conserved patch on the cavity wall these include Phe-16, Tyr-19, Met-20, Val-23, and Ala-33 (ALBP numbering scheme). 

Some comments are helpful. Kryptates encapsulate alkali or akaline-earth cations and convert tight ion-pairs, or some still larger aggregates, into loose pairs. This transformation decreases the lattice energy of the salt. Moreover, the interaction of kryptated cations with hydrocarbon solvents is improved because it is the external, hydrophobic shell of the complex that contacts the surroundings. The combined effect of both factors makes the complexes more soluble in hydrocarbons than the uncomplexed salts. 

Mueller W, Koynov K, Fischer K, Hartmann S, Pierrat S, Basche T, Maskos M (2009) Hydrophobic shell loading of PB-b-PEO vesicles. Macromolecules 42 357-361... 

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