Related Experiment Video
Updated: Aug 9, 2026
08:48
High-Resolution Neutron Spectroscopy to Study Picosecond-Nanosecond Dynamics of Proteins and Hydration Water
Published on: April 28, 2022
Cross-relaxation bottleneck in water-lysozyme proton magnetization exchange
J F Kakule1, A R Sharp, L J Schreiner
1Department of Physics, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3.
Biopolymers
|April 15, 2006
Summary
Magnetic coupling mixes protein and water proton magnetizations in lysozyme solutions. This effect is explained by an exchange cross-relaxation model involving labile and nonlabile protons.
Area of Science:
- Biophysics
- Chemical Physics
- Molecular Biophysics
Background:
- Proton spin-lattice relaxation is crucial for understanding molecular dynamics in biological systems.
- Lysozyme solutions provide a model system for studying protein-water interactions.
Purpose of the Study:
- To investigate the proton spin-lattice relaxation parameters in natural and deuterated lysozyme solutions.
- To elucidate the mechanism of magnetic coupling between protein and water protons.
Main Methods:
- Proton spin-lattice relaxation measurements were performed on lysozyme solutions.
- Experiments were conducted across a temperature range of 0-50 degrees C.
- Data analysis was guided by an established exchange cross-relaxation model.
Main Results:
- Temperature-dependent variations in water proton magnetization magnitudes were observed.
- These variations indicate magnetic coupling and mixing of protein and water proton magnetizations.
- The findings align with an exchange cross-relaxation model between labile and nonlabile protons.
Conclusions:
- An exchange cross-relaxation mechanism between labile and nonlabile protons influences magnetization fractions in lysozyme solutions.
- While affecting magnetization fractions, this pathway's impact on relaxation rates is less pronounced.
- The study refines understanding of proton dynamics and magnetic interactions in protein solutions.
Related Concept Videos
01:28Atomic Nuclei: Types of Nuclear Relaxation
Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...