Informing saccharide structural NMR studies with density functional theory calculations.

Area of Science:

• Carbohydrate Chemistry
• Computational Chemistry
• Structural Biology

Background:

• NMR spin-spin coupling constants (J-couplings) are crucial for saccharide structure determination.
• Hydroxyl groups in saccharides significantly influence J-couplings, presenting interpretation challenges.
• Conformational averaging in solution complicates experimental analysis of saccharide structures.

Purpose of the Study:

• To utilize Density Functional Theory (DFT) for interpreting NMR J-couplings in saccharides.
• To elucidate the influence of hydroxyl groups on J-couplings and molecular conformation.
• To establish quantitative relationships between J-couplings and conformational elements.

Main Methods:

• Application of Density Functional Theory (DFT) calculations.
• Analysis of (1)H-(1)H (JHH), (13)C-(1)H (JCH), and (13)C-(13)C (JCC) coupling constants.
• Investigation of oxygen substituent effects on J-couplings.

Main Results:

• DFT provides structural interpretations for J-couplings in saccharides.
• Quantitative relationships were established between J-couplings and conformational elements.
• Oxygen substituent effects on J-couplings were linked to configurational and conformational origins.
• Redundant J-couplings were identified as valuable for flexible conformational elements.

Conclusions:

• DFT is a powerful tool for understanding saccharide conformation via J-coupling analysis.
• The findings aid in studying saccharide structure and conformation in solution.
• This approach can help validate and refine computational methods like molecular dynamics (MD) simulations.