A low-E magic angle spinning probe for biological solid state NMR at 750 MHz

Area of Science:

• Biophysical Chemistry
• Magnetic Resonance Spectroscopy
• Materials Science

Background:

• Conventional Nuclear Magnetic Resonance (NMR) probes can cause significant sample heating, particularly at high frequencies.
• This heating effect is a major limitation for studying biological samples, especially dilute systems like proteins in lipid bilayers.
• Minimizing radiofrequency-induced heating is crucial for obtaining high-quality data in solid-state NMR.

Purpose of the Study:

• To develop and characterize a novel magic angle spinning (MAS) solid-state NMR probe with reduced sample heating.
• To enable the study of dilute biological systems under physiologically relevant conditions using MAS NMR.
• To demonstrate the efficacy of the "low-E" dual resonator approach for improved NMR performance.

Main Methods:

• Development of a dual resonator probe system, termed "low-E," based on crossed-coil NMR principles.
• Implementation of a low-inductance resonator to reduce the driving voltage and electric field across the sample.
• Testing the probe's performance using windowless dipolar recoupling sequences on model compounds and membrane-embedded peptides.

Main Results:

• The developed "low-E" probe successfully reduces sample heating by minimizing the radiofrequency electric field.
• Achieved homogeneous and strong radiofrequency fields for both proton (1H) and carbon-13 (13C) nuclei at a 750 MHz proton frequency in a 4mm probe.
• Demonstrated effective performance for studying challenging samples, including membrane proteins.

Conclusions:

• The "low-E" dual resonator MAS NMR probe is an effective tool for reducing sample heating in solid-state NMR.
• This technology significantly enhances the capability to study dilute biological systems at high magnetic fields.
• The probe design offers improved signal-to-noise ratios for complex biological samples, advancing biophysical studies.