Conformational analysis

The glycosylation shifts in αlinked gluco and
galacto residues have been related to the ^{1}H^{1}H
distance across the glycosidic linkage and the ψ_{H} torsion
angle. The observation that chemical shift changes (Δδ_{C}) are related to the protonproton distance between interacting carbons was originally made in hydrocarbons. In carbohydrates various electronic and stereoelectronic effects play a much greater role and often obscure the effect of short ^{1}H^{1}H distances. Thus, this equation is only valid for αlinkages and only for a limited range of torsion angles. There are newer attempts at correlations between the ^{13}C chemical shifts of the anomeric and the glycosylated carbon resonances, in particular for solid state studies of starches and celluloses, but they are all rather limited in scope.
Since the ^{1}H^{1}H distances are related to the glycosidic torsion angles the following relationships can be derived (assuming that φ_{H} remains constant):
Note that this relation implies that the glycosylation shifts of the two
carbon atoms on opposite sides should be almost the same. This gives an idea of how
accurate the relation, at best, can be expected to be.
This is a toy  do not rely on the results! Enter the glycosylations shifts below to get an estimate of ψ_{H} and r_{H,H}. The relation has been derived from values in the following ranges: 2.2<r_{H,H}<3.0 0<Δδ_{C}<10 55°<ψ_{H}<5° φ_{H} is assumed to be constant, somewhere in the range 40°60°.
"Conformational Dependence of ^{13}C Nuclear Magnetic Resonance Chemical Shifts in Oligosaccharides", K. Bock, A. Brignole and B. W. Sigurskjold; J.C.S., Perkin Trans. II (1986) 17111713. 