## Abstract Two conformers of fosinopril sodium in methanol were unambiguously established using 2D NMR methods and variable‐temperature NMR experiments. Differences in their conformational structure were shown to be related to the rotational energy barrier about the amide bond and hydrophobic inte
Conformational study of digalacturonic acid and sodium digalacturonate in solution
✍ Scribed by Catherine Gouvion; Karim Mazeau; Alain Heyraud; François R. Taravel; Igor Tvaroska
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 984 KB
- Volume
- 261
- Category
- Article
- ISSN
- 0008-6215
No coin nor oath required. For personal study only.
✦ Synopsis
The solution conformation of digalacturonic acid and its sodium salt have been analyzed using nuclear magnetic resonance data and molecular mechanics calculations. The flexibility around the glycosidic linkage was characterized by calculation of the relaxed (phi, psi) potential surfaces for the isolated molecule, and also for dimethyl sulfoxide and aqueous solutions using the CHARMM and SOLVOL programs. The one-bond and three-bond proton-carbon couplings were measured and H-1'-H-4 distances were estimated from NOESY experiments. The calculated potential surfaces were used to determine theoretical ensemble averages of NMR data. The agreement between the experimental and theoretical data is very satisfactory. The calculations show a strong effect of solvent on the solution behavior of both compounds. The vacuum lowest energy conformer of digalacturonic acid is stabilized by solvation, while for sodium digalacturonate the solvent induces a conformational change. An extrapolation of the stable conformers to polysaccharide chains implies that poly(galacturonic acid) occurs in solution as a three-fold helix and sodium poly(galacturonate) as a two-fold helix.
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