⁷⁷Se-¹³C based dipolar correlation experiments to map selenium sites in microcrystalline proteins

Area of Science:

• Biophysics
• Structural Biology
• NMR Spectroscopy

Background:

• Sulfur sites are crucial for protein structure and function.
• Selenium-77 NMR offers a sulfur analog for protein studies.
• Selenomethionine is valuable for NMR in complex systems.

Purpose of the Study:

• To explore 77Se-13C dipolar transfer mechanisms for protein structural characterization.
• To demonstrate the utility of 77Se-13C correlations for mapping selenium environments.
• To establish a framework for characterizing selenium sites at protein interfaces.

Main Methods:

• Utilized (1H)-77Se-13C double cross polarization and {77Se}-13C REDOR.
• Applied methods to the GB1 V39SeM variant of the model protein GB1.
• Investigated dipolar transfer mechanisms for structural insights.

Main Results:

• Successfully demonstrated 77Se-13C based correlations for mapping selenium environments.
• Established a general detection limit of approximately 5 Å.
• Observed longer-range distances up to approximately 7 Å.

Conclusions:

• 77Se-13C correlations provide a powerful tool for characterizing selenium sites in proteins.
• This method enables mapping of local environments around selenium, aiding structural analysis.
• The study lays the groundwork for future investigations of selenium at protein-protein and protein-ligand interfaces.