Proton nuclear magnetic resonance studies on dideoxyribonucleoside methylphosphonates

Area of Science:

• Organic Chemistry
• Biochemistry
• Molecular Biology

Background:

• Dideoxyribonucleoside methylphosphonates are novel nonionic nucleic acid analogues.
• Understanding their structure-activity relationship is crucial for developing new therapeutic agents.

Purpose of the Study:

• To synthesize dideoxyribonucleoside methylphosphonates and their diastereoisomers.
• To elucidate the conformational properties of these analogues using spectroscopic techniques.

Main Methods:

• Chemical synthesis of dinucleoside methylphosphonates (d-ApA, d-ApT, d-TpA, TpT).
• Separation of diastereoisomers.
• 1H Nuclear Magnetic Resonance (NMR) spectroscopy and spectrum simulation.
• Nuclear Overhauser Effect (NOE) technique for absolute configuration determination.
• Computer analysis for base stacking conformations.

Main Results:

• Precise determination of coupling constants and chemical shifts for deoxyribofuranose ring and phosphonate methyl group protons.
• Conformations of sugar-phosphate backbones are similar across isomers and to parent dinucleoside monophosphates.
• Distinct base stacking modes observed between isomer 1 and isomer 2, with isomer 1 showing greater base overlap.

Conclusions:

• The synthesized nonionic nucleic acid analogues possess conformations similar to natural dinucleoside monophosphates.
• NMR data provide insights into sugar puckering and backbone flexibility.
• Differences in base stacking between diastereoisomers may influence their biological activity.