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Experimental chiroptical verification of linkage flexibility in methyl 3‐ O ‐(α‐ D ‐mannopyranosyl)‐α‐ D ‐mannopyranoside
Author(s) -
Arndt Edward R.,
Stevens Eugene S.
Publication year - 1996
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(199605)38:5<567::aid-bip2>3.0.co;2-q
Subject(s) - disaccharide , chemistry , monosaccharide , stereochemistry , linkage (software) , crystallography , spectral line , optical rotation , organic chemistry , biochemistry , physics , astronomy , gene
Vacuum UV CD spectra of methyl 3‐O‐(α‐ D ‐mannopyranosyl)‐α‐ D ‐mannopyranoside in D 2 O and as a cast film were obtained in the 145–200 nM region. The disaccharide solution CD per residue is nearly identical to that of the monosaccharide solution CD, and to the monosaccharide film CD. Conversely, the disaccharide film spectrum exhibits a strong positive CD linkage contribution in the 160–170 nm range, which is consistent with the known crystal conformation under the aegis of previously determined sector rules. The close similarity between the monosaccharide and disaccharide solution spectra, therefore, reflects conformational averaging in which the net linkage contribution is approximately zero. The present observation of significant solution linkage flexibility confirms previous conclusions based on optical rotation, as well as conclusions of others based on nmr data. Moreover, when combined with those earlier results, the present work demonstrates the population of at least three distinct potential energy wells on the disaccharide ϕ, ψ potential energy surface. © 1996 John Wiley & Sons, Inc.