Structural analysis of 11C, 15N labeled adenosine by solid-state NMR

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Organic chemistry and structural elucidation.
• Biophysical characterization of biomolecules.

Background:

• Nuclear Magnetic Resonance (NMR) is a powerful technique for determining molecular structure.
• Solid-state NMR is crucial for studying molecules in their native, non-crystalline states.
• Understanding covalent bonding networks is fundamental to molecular structure.

Purpose of the Study:

• To apply two-dimensional (2D) solid-state NMR experiments to map covalent connectivities in adenosine.
• To assign all carbon-13 (13C) and nitrogen-15 (15N) signals in adenosine using dipolar couplings.
• To demonstrate the utility of specific NMR pulse sequences for solid-state structural analysis.

Main Methods:

• Utilized 2D solid-state 13C homonuclear and 13C-15N heteronuclear NMR experiments.
• Employed Uniform Enhancement by Multiple Echo (USEME) and Transverse Enables Dipolar Recoupling (TEDOR) pulse sequences.
• Synchronized radiofrequency (rf) multipulse sequences with magic angle spinning (MAS) for dipolar interaction recovery.

Main Results:

• Successfully assigned all 13C and 15N signals in uniformly labeled adenosine.
• Identified spin pairs connected by direct covalent bonds through cross-peak analysis in 2D spectra.
• Unveiled a detailed network of covalently linked 13C and 15N spins within the solid adenosine structure.

Conclusions:

• 2D solid-state NMR experiments effectively map covalent bond networks in organic solids.
• The employed NMR techniques provide high-resolution structural information for molecules like adenosine.
• This methodology offers a robust approach for structural elucidation of complex solid-state systems.