Proton dipolar recoupling in resin-bound peptides under high-resolution magic angle spinning

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) Spectroscopy
• Biophysical Chemistry
• Materials Science

Background:

• Proton dipolar interactions in peptides bound to soft materials are weak and difficult to detect.
• Traditional Nuclear Overhauser Effect Spectroscopy (NOESY) experiments yield low signal intensity for such systems.
• Magic angle spinning is employed to average out anisotropic interactions.

Purpose of the Study:

• To investigate the efficacy of rotational resonance and radiofrequency-driven dipolar recoupling (RFDR) experiments for detecting proton dipolar interactions in peptides.
• To compare the performance of RFDR with classical NOESY experiments.
• To explore magnetization transfer mechanisms in soft materials under magic angle spinning conditions.

Main Methods:

• Application of rotational resonance and RFDR NMR sequences.
• Magic angle spinning of peptide-bound swollen resins.
• Comparison of correlation peak intensities with NOESY experiments.
• Analysis of magnetization transfer pathways, including scalar J-coupling.

Main Results:

• Rotational resonance and RFDR experiments successfully recover weak proton dipolar interactions.
• RFDR yields significantly stronger correlation peak intensities than classical NOESY.
• RFDR facilitates magnetization transfer via scalar J-coupling during long mixing times in soft materials.

Conclusions:

• RFDR and rotational resonance are superior methods for studying proton dipolar couplings in peptides within soft matrices.
• RFDR offers enhanced sensitivity and reveals additional magnetization transfer mechanisms.
• These techniques advance the structural and dynamic analysis of biomolecules in complex environments.