Comprehensive analysis of relaxation decays from high-resolution relaxometry

Area of Science:

• Nuclear Magnetic Resonance (NMR) spectroscopy
• Biophysical chemistry
• Computational chemistry

Background:

• Relaxometry measures relaxation rates across magnetic fields to study complex system dynamics.
• High-resolution relaxometry (HRR) uses NMR magnets and sample shuttles to probe motions.
• Current HRR methods face challenges in accurately determining pure relaxation rates due to cross-relaxation effects outside the probe.

Purpose of the Study:

• To develop a more self-consistent and generally applicable analysis protocol for HRR data.
• To overcome limitations of previous methods that relied on correction factors and mono-exponential decay approximations.
• To introduce a novel framework that directly analyzes experimental and simulated relaxometry decays.

Main Methods:

• Introduction of the Matching INtensities for the Optimization of Timescales and Amplitudes of motions Under Relaxometry (MINOTAUR) framework.
• Utilizing the full relaxation matrix to compute intensity decays, inherently accounting for complex relaxation pathways.
• Designing MINOTAUR as a flexible software accommodating various models of molecular motion and spectral density functions.

Main Results:

• MINOTAUR eliminates the need for decay rate corrections and fitting multi-exponential decays with mono-exponential functions.
• The framework demonstrates excellent agreement with previous analyses of protein side-chain dynamics using carbon-13 relaxation.
• Provides a more robust and accurate tool for analyzing HRR data compared to existing methods.

Conclusions:

• MINOTAUR offers a superior, self-consistent approach to HRR data analysis.
• The framework enhances the reliability of describing molecular dynamics from relaxometry experiments.
• MINOTAUR is poised to become the standard tool for high-resolution relaxometry analysis.