Enhancing the Sensitivity of CPMG Relaxation Dispersion to Conformational Exchange Processes by Multiple-Quantum Spectroscopy

2016 ◽  
Vol 55 (38) ◽  
pp. 11490-11494 ◽  
Author(s):  
Tairan Yuwen ◽  
Pramodh Vallurupalli ◽  
Lewis E. Kay
Keyword(s):  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Multiple Quantum ◽  
Exchange Processes ◽  
Cpmg Relaxation Dispersion

scholarly journals Analysis of Conformational Exchange Processes using Methyl-TROSY-Based Hahn Echo Measurements of Quadruple-Quantum Relaxation

2021 ◽  
Author(s):  
Christopher Andrew Waudby ◽  
John Christodoulou
Keyword(s):  
Chemical Shift ◽  
Chemical Exchange ◽  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Parameter Estimates ◽  
Relaxation Rates ◽  
Exchange Processes ◽  
Methyl Trosy ◽  
Quantum Transitions ◽  
Order Of Magnitude

Abstract. Transverse nuclear spin relaxation is a sensitive probe of chemical exchange on timescales on the order of microseconds to milliseconds. Here we present an experiment for the simultaneous measurement of the relaxation rates of two quadruple-quantum transitions in 13CH3-labelled methyl groups. These coherences are protected against relaxation by intra-methyl dipolar interactions, and so have unexpectedly long lifetimes within perdeuterated biomacromolecules. However, these coherences also have an order of magnitude higher sensitivity to chemical exchange broadening than lower order coherences, and therefore provide ideal probes of dynamic processes. We show that analysis of the static magnetic field dependence of zero-, double- and quadruple-quantum Hahn echo relaxation rates provides a robust indication of chemical exchange, and can determine the signed relative magnitudes of proton and carbon chemical shift differences between ground and excited states. We also demonstrate that this analysis can be combined with established CPMG relaxation dispersion measurements, providing improved precision in parameter estimates, particularly in the determination of 1H chemical shift differences.

scholarly journals Analysis of conformational exchange processes using methyl-TROSY-based Hahn echo measurements of quadruple-quantum relaxation

2021 ◽  
Vol 2 (2) ◽  
pp. 777-793
Author(s):  
Christopher A. Waudby ◽  
John Christodoulou
Keyword(s):  
Chemical Shift ◽  
Chemical Exchange ◽  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Parameter Estimates ◽  
Relaxation Rates ◽  
Exchange Processes ◽  
Methyl Trosy ◽  
Quantum Transitions ◽  
Order Of Magnitude

Abstract. Transverse nuclear spin relaxation is a sensitive probe of chemical exchange on timescales on the order of microseconds to milliseconds. Here we present an experiment for the simultaneous measurement of the relaxation rates of two quadruple-quantum transitions in 13CH3-labelled methyl groups. These coherences are protected against relaxation by intra-methyl dipolar interactions and so have unexpectedly long lifetimes within perdeuterated biomacromolecules. However, these coherences also have an order of magnitude higher sensitivity to chemical exchange broadening than lower order coherences and therefore provide ideal probes of dynamic processes. We show that analysis of the static magnetic field dependence of zero-, double- and quadruple-quantum Hahn echo relaxation rates provides a robust indication of chemical exchange and can determine the signed relative magnitudes of proton and carbon chemical shift differences between ground and excited states. We also demonstrate that this analysis can be combined with established Carr–Purcell–Meiboom–Gill (CPMG) relaxation dispersion measurements, providing improved precision in parameter estimates, particularly in the determination of 1H chemical shift differences.

scholarly journals Analysis of Conformational Exchange Processes using Methyl-TROSY-Based Hahn Echo Measurements of Quadruple-Quantum Relaxation

2021 ◽  
Author(s):  
Christopher Andrew Waudby ◽  
John Christodoulou
Keyword(s):  
Chemical Shift ◽  
Excited States ◽  
Chemical Exchange ◽  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Nuclear Spin Relaxation ◽  
Relaxation Rates ◽  
Exchange Processes ◽  
Methyl Trosy

Transverse nuclear spin relaxation can be a sensitive probe of chemical exchange on timescales on the order of microseconds to milliseconds. Here we present an experiment for the simultaneous measurement of the relaxation rates of two four-spin transitions in selectively protonated methyl groups within perdeuterated biomacromolecules, alongside control experiments for measurement of 1H and 13C chemical shift anisotropies. We show that analysis of the static magnetic field dependence of zero-, double- and quadruple-quantum Hahn echo relaxation rates provides a robust indication of chemical exchange and determines the signed relative magnitudes of proton and carbon chemical shift differences between ground and excited states. The analysis can be combined with CPMG relaxation dispersion measurements to provide improved precision, particularly in the determination of 1H chemical shift differences.

scholarly journals Mapping transiently formed and sparsely populated conformations on a complex energy landscape

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yong Wang ◽  
Elena Papaleo ◽  
Kresten Lindorff-Larsen
Keyword(s):  
Energy Landscape ◽  
Nmr Relaxation ◽  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Internal Cavity ◽  
T4 Lysozyme ◽  
Enhanced Sampling ◽  
Exchange Processes ◽  
Dynamics Simulations ◽  
A Minor

Determining the structures, kinetics, thermodynamics and mechanisms that underlie conformational exchange processes in proteins remains extremely difficult. Only in favourable cases is it possible to provide atomic-level descriptions of sparsely populated and transiently formed alternative conformations. Here we benchmark the ability of enhanced-sampling molecular dynamics simulations to determine the free energy landscape of the L99A cavity mutant of T4 lysozyme. We find that the simulations capture key properties previously measured by NMR relaxation dispersion methods including the structure of a minor conformation, the kinetics and thermodynamics of conformational exchange, and the effect of mutations. We discover a new tunnel that involves the transient exposure towards the solvent of an internal cavity, and show it to be relevant for ligand escape. Together, our results provide a comprehensive view of the structural landscape of a protein, and point forward to studies of conformational exchange in systems that are less characterized experimentally.

scholarly journals Analysis of Artifacts Caused by Pulse Imperfections in CPMG Pulse Trains in NMR Relaxation Dispersion Experiments

2018 ◽  
Vol 4 (3) ◽  
pp. 33 ◽  
Author(s):  
Tsuyoshi Konuma ◽  
Aritaka Nagadoi ◽  
Jun-ichi Kurita ◽  
Takahisa Ikegami
Keyword(s):  
Dipolar Coupling ◽  
Residual Dipolar Coupling ◽  
Nmr Relaxation ◽  
Relaxation Dispersion ◽  
Conformational Exchange ◽  
Resonance Effects ◽  
Pulse Trains ◽  
At Resonance ◽  
Selective Inversion ◽  
Resonance Relaxation

Nuclear magnetic resonance relaxation dispersion (rd) experiments provide kinetics and thermodynamics information of molecules undergoing conformational exchange. Rd experiments often use a Carr-Purcell-Meiboom-Gill (CPMG) pulse train equally separated by a spin-state selective inversion element (U-element). Even with measurement parameters carefully set, however, parts of 1H–15N correlations sometimes exhibit large artifacts that may hamper the subsequent analyses. We analyzed such artifacts with a combination of NMR measurements and simulation. We found that particularly the lowest CPMG frequency (νcpmg) can also introduce large artifacts into amide 1H–15N and aromatic 1H–13C correlations whose 15N/13C resonances are very close to the carrier frequencies. The simulation showed that the off-resonance effects and miscalibration of the CPMG π pulses generate artifact maxima at resonance offsets of even and odd multiples of νcpmg, respectively. We demonstrate that a method once introduced into the rd experiments for molecules having residual dipolar coupling significantly reduces artifacts. In the method the 15N/13C π pulse phase in the U-element is chosen between x and y. We show that the correctly adjusted sequence is tolerant to miscalibration of the CPMG π pulse power as large as ±10% for most amide 15N and aromatic 13C resonances of proteins.

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