Torsional averaging process

It is clear that the function U ( qint ) tmy be approximated by an expression of the form of eqn. (6). Whether a potential of Ais form, involving no explicit description of the solvent, is appropriate depends on the relative relaxation rates of the solvent motions and the macromolecular intramolecular coordinates. For the slow, conformationally most significant, glycosidic and exocyclic bond rotations of the carbohydrate it is apparent Aat averaging of solvent motions can occur easily on the time scale of these torsions. It is more ficult, however, to know how much important conformational detail is submerged by the averaging process. 

We think that the constancy of the n.O.e. values can be explained in this case by the averaging process during the NMR experiment (34). Since n.L.e. values and coupling constants depend in different, nonlinear ways on proton-proton distances and torsion angles, the time-averaged values of the geometrical parameters derived from n.O.e. values can differ from parsimeters indicated by coupling constants. 

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