Buried polar groups

Diss, M. L. Kennan, A. J. Orthogonal recognition in dimeric coiled coils via buried polar-group modulation. J. Am. Chem. Soc. 2008,130,1321-1327. 

The seven helices of rhodopsin form a "box" around the bound retinal. Tire environment of the retinal is largely hydrophobic. However, there are also buried polar groups, some of which lie in conserved positions in more than 200 G-protein-coupled receptors458 and internal water molecules whose vibrational... 

Water binding varies with the number and type of polar groups (5 ). Other factors that affect the mechanism of protein-water interactions include protein conformation and environmental factors that affect protein polarity and/or conformation. Conformational changes in the protein molecules can affect the nature and availability of the hydration sites. Transition from globular to random coil conformation may expose previously buried amino acid side chains, thereby making them available to interact with aqueous medium. Consequently, an unfolded conformation may permit the protein to bind more water than was possible in the globular form ( ). 

Surface molecules with their polar groups buried are called endotropic , this is the normal stable position. Such surfaces have little reactivity or adsorptive power. Multilayer surfaces may be conditioned , the top... 

Lawrence (1937) first noted that the site of incorporation of solubilized molecules depended on their relative hydrophobic and hydrophilic tendencies. The solubilizate may be entrapped in the hydrocarbon core of the micelle, be oriented radially in the micelle with its polar group buried (deep penetration) or near the surface (short penetration), or be adsorbed on the surface of the micelle. Additionally, for non-ionic surfactants, incorporation of the solubilizate can occur in the polyoxyethylene shell of the surfactant. Fig. 3 illustrates several modes of solubilizate incorporation. It is important to realize, however, that solubilization, like micelle formation, is not a static but a dynamic equilibrium process. 

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