Proton spectroscopy biological molecules

Time-resolved Raman spectroscopy has proved to be a very useful tool to elucidate fast processes in biological molecules, for instance, to follow the fast structural changes during the visual process where, after photoexcitation of rhodopsin molecules, a sequence of energy transfer processes involving isomerization and proton transfer takes place. This subject is treated in more detail in Chap. 6 in comparison with other time-resolved techniques. 

The several theoretical and/or simulation methods developed for modelling the solvation phenomena can be applied to the treatment of solvent effects on chemical reactivity. A variety of systems - ranging from small molecules to very large ones, such as biomolecules [236-238], biological membranes [239] and polymers [240] -and problems - mechanism of organic reactions [25, 79, 223, 241-247], chemical reactions in supercritical fluids [216, 248-250], ultrafast spectroscopy [251-255], electrochemical processes [256, 257], proton transfer [74, 75, 231], electron transfer [76, 77, 104, 258-261], charge transfer reactions and complexes [262-264], molecular and ionic spectra and excited states [24, 265-268], solvent-induced polarizability [221, 269], reaction dynamics [28, 78, 270-276], isomerization [110, 277-279], tautomeric equilibrium [280-282], conformational changes [283], dissociation reactions [199, 200, 227], stability [284] - have been treated by these techniques. Some of these... 

In Chapter 3 (Section 3.16), there is a description of the nuclear Overhauser effect difference experiment, an experiment that provides information about H— H through-space proximity. Review of this section is helpful before proceeding here. The ROESY experiment, rotating-frame Overhauser effect spectroscopy, is a useful 2-D analogue of the nuclear Overhauser effect difference experiment. This experiment is useful for molecules of all sizes whereas the related experiment, NOESY (nuclear Overhauser effect spectroscopy), is not very useful with small molecules. NOESY is used primarily with biological macromolecules. Both NOESY and ROESY experiments correlate protons that are close to each other in space, typically 4.5 A or less. 

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