Long-range (1)H-(15)N heteronuclear shift correlation at natural abundance

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Structural Biology
• Analytical Chemistry

Background:

• Nitrogen-15 ((15)N) NMR spectroscopy offers valuable structural insights but is limited by low natural abundance (0.37%) and low gyromagnetic ratio (gamma(N)), impacting sensitivity.
• Traditional (15)N NMR experiments often require isotopic enrichment, limiting applications for certain sample types or research scenarios.

Purpose of the Study:

• To demonstrate the utility of (15)N NMR as a structural probe at natural abundance.
• To review and discuss methodologies for acquiring and analyzing long-range (1)H-(15)N heteronuclear shift correlation data.
• To highlight the practical applications and potential of these advanced NMR techniques.

Main Methods:

• Utilized inverse-detected NMR methods, leveraging significant advancements in NMR probe design.
• Acquired long-range (1)H-(15)N heteronuclear shift correlation data.
• Discussed chemical shift referencing, (15)N shift ranges, pulse sequences, calibration, parametrization, data processing, and probe selection.

Main Results:

• Demonstrated the feasibility of obtaining high-quality long-range (1)H-(15)N correlation data with millimole sample sizes overnight.
• Provided a comprehensive overview of the technical aspects required for successful (15)N natural abundance experiments.
• Reviewed literature applications emphasizing observed long-range coupling pathways.

Conclusions:

• Inverse-detected NMR methods and advanced probes significantly enhance the sensitivity of (15)N NMR, enabling structural studies at natural abundance.
• Long-range (1)H-(15)N heteronuclear shift correlation experiments are powerful tools for molecular structure elucidation, even with limited sample quantities.
• This approach expands the applicability of NMR spectroscopy in structural biology and chemical analysis.