Molecular recognition physical basis

Local hydrophobicityplays an important role in molecular recognition processes. It is generally accepted that the hydrophobic interaction between two molecules is related to both energetic and entropic contributions, but there is still no simple physical model available for hydrophobicity and hydrophobic interactions. However, there have been several attempts to define relative hydrophobicity values on the basis of empirical findings. 

DNA as a polyelectrolyte in saline solution presents a unique chemistry and physics in terms of the complementary self pairing, known biologically as Watson-Crick hybridization. The free energies of association in solution are well studied and form the basis for the normal molecular recognition process. This process is fundamentally altered by the presence of a solid interface. 

Many attempts have been made to understand and quantify the fundamental physical basis for molecular recognition, i.e., why two molecules do or do not interact, (Fig. 1). As the imprinting process is a direct consequence of molecular recognition events, i.e., template-monomer interaction, insights into the fundamental physical basis for molecular recognition should prove useful. 

The valinomycin study just described illustrates the value of close comparison of NMR and X-ray diffraction data. Correlation of NMR assignments with X-ray data for known structures may allow the subsequent elucidation of conformational features for related materials on the basis of NMR data alone. It is notoriously difficult to relate solid-state structures determined by X-ray diffraction to the solution conformation observed by conventional NMR spectroscopy, although data from the former technique are often the only type available for work on receptor recognition. However, solid-state NMR may provide a link between these two techniques by indicating whether molecular conformation changes do occur when the physical state is altered. In contrast to the valinomycin complexes discussed above, it has been found that significant differences in the solution and solid-state spectra of morphine... 

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