Hydrophobic and hydrogen-bonding interactions

Analysis of the crystallographic structure also reveals that the two domains interact primarily through hydrophobic and hydrogen bond interactions at the interface. The number of apolar hydrogens that become exposed on the C domain on unfolding of the N domain is 49.4, and the number of apolar hydrogens exposed on the N domain on unfolding of the C domain is 44.8. These values correspond to 726 and 659 A2 of apolar surface area, respectively. In addition, nine... 

Nanoparticles are unstable under strongly acidic conditions. Indeed, NPs protected by a mixed monolayer composed of a 1 1 mixture of dodecanethiolate and triethylene glycol thiolates aggregate under strongly acidic conditions. Interestingly, these authors reported that the acid induces the formation of clusters of these MPCs and that the extent and the rate of cluster formation is the result of a subtle balance between hydrophobic and hydrogen bonding interactions between particles and between the particles and the solvent.157... 

A dramatic example of an alternative solvent is use of water for the Diels-Alder reaction of a fiiranyl acrylic acid the rate was foimd to be 153 times faster than the corresponding reaction in hexane (Equation 6). It was proposed that enforced hydrophobic and hydrogen bonding interactions are responsible. 

In the 1980s, Breslow s group found that an increased reaction rate occurred in water in the reaction between cyclopentadiene and butanone (Equation 4.13) [22]. Curiously, the reaction rate in methanol was similar to that in other organic solvents, and the strange acceleration in water was assigned to hydrophobic and hydrogen bonding interactions [23]. 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

Klusak et al. have studied the binding of BmorPBP with bombykol using high-level ab initio methods. The shape of the cavity, which is critical for selectivity, is defined by amino acid residues that show no direct interaction with bombykol, yet these residues are not conserved and, therefore, are distinct for the BmorPBP binding cavity. In conclusion, specific hydrophobic and hydrogen bonding interactions... 

In the above sections, the contributions of electrostatic, hydrophobic, and hydrogen-bonding interactions in the catalytic influence of polyelectrolytes in various types of reactions have been discussed. ... 

The native state of a single-domain protein is its tertiary structure, and it is estimated that approximately 1000 different shapes or folds exist in nature. The native state generally adopts a globular three-dimensional shape, stabilized by both covalent (peptide bonds, disulfide bridges) and noncovalent (electrostatic, hydrophobic and hydrogen bonds) interactions. Local structures within the native fold are known as secondary structures, with common motifs including alpha heHces and beta sheets. The classic experiments of Anfinsen et al. su ested a Thermodynamic Hypothesis for folding, in which the... 

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