Dr. Emmanuelle Weber is a physicist that obtained a Ph.D. focused on the development and applications of the Dynamic Nuclear Polarization (DNP) method. She allied NMR and EPR spectroscopy studies in her research and recently joined Dr. McNab’s group to work on diffusion MRI.
Doctor of Philosophy, Ecole Normale Superieure (2018)
Bachelor of Arts and Science, Universite De Strasbourg (2013)
Master of Science, Universite De Grenoble (2015)
Sample Ripening through Nanophase Separation Influences the Performance of Dynamic Nuclear Polarization
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2018; 57 (18): 5171–75
Mixtures of water and glycerol provide popular matrices for low-temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially influence the efficiency of dynamic nuclear polarization (DNP) by factors up to 20 % by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30-60 min results in a confinement of polarization agents in nanoscopic water-rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl.
View details for DOI 10.1002/anie.201800493
View details for Web of Science ID 000432382800066
View details for PubMedID 29431894
Rates of Chemical Reactions Embedded in a Metabolic Network by Dissolution Dynamic Nuclear Polarisation NMR
CHEMISTRY-A EUROPEAN JOURNAL
2018; 24 (21): 5456–61
The isomerisation of 6-phosphogluconolactones and their hydrolyses into 6-phosphogluconic acid form a non enzymatic side cycle of the pentose-phosphate pathway (PPP) in cells. Dissolution dynamic nuclear polarisation can be used for determining the kinetic rates of the involved transformations in real time. It is found that the hydrolysis of both lactones is significantly slower than the isomerisation process, thereby shedding new light onto this subtle chemical process.
View details for DOI 10.1002/chem.201705520
View details for Web of Science ID 000430169400009
View details for PubMedID 29356139
Anisotropic longitudinal electronic relaxation affects DNP at cryogenic temperatures
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
2017; 19 (24): 16087–94
We report the observation of anisotropic longitudinal electronic relaxation in nitroxide radicals under typical dynamic nuclear polarization conditions. This anisotropy affects the efficiency of dynamic nuclear polarization at cryogenic temperatures of 4 K and high magnetic fields of 6.7 T. Under our experimental conditions, the electron paramagnetic resonance spectrum of nitroxides such as TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) is only partly averaged by electronic spectral diffusion, so that the relaxation times T1e(ω) vary across the spectrum. We demonstrate how the anisotropy of T1e(ω) can be taken into account in simple DNP models.
View details for DOI 10.1039/c7cp03242k
View details for Web of Science ID 000403965500051
View details for PubMedID 28598474
Communication: Dissolution DNP reveals a long-lived deuterium spin state imbalance in methyl groups
JOURNAL OF CHEMICAL PHYSICS
2017; 146 (4): 041101
We report the generation and observation of long-lived spin states in deuterated methyl groups by dissolution DNP. These states are based on population imbalances between manifolds of spin states corresponding to irreducible representations of the C3v point group and feature strongly dampened quadrupolar relaxation. Their lifetime depends on the activation energies of methyl group rotation. With dissolution DNP, we can reduce the deuterium relaxation rate by a factor up to 20, thereby extending the experimentally available time window. The intrinsic limitation of NMR spectroscopy of quadrupolar spins by short relaxation times can thus be alleviated.
View details for DOI 10.1063/1.4974358
View details for Web of Science ID 000394520200002
View details for PubMedID 28147551
Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
2017; 56 (1): 389–92
Hyperpolarized water can selectively enhance NMR signals of rapidly exchanging protons in osteopontin (OPN), a metastasis-associated intrinsically disordered protein (IDP), at near-physiological pH and temperature. The transfer of magnetization from hyperpolarized water is limited to solvent-exposed residues and therefore selectively enhances signals in 1 H-15 N correlation spectra. Binding to the polysaccharide heparin was found to induce the unfolding of preformed structural elements in OPN.
View details for DOI 10.1002/anie.201608903
View details for Web of Science ID 000394861200065
View details for PubMedID 27918140
Dissolution dynamic nuclear polarization of deuterated molecules enhanced by cross-polarization
JOURNAL OF CHEMICAL PHYSICS
2016; 145 (19): 194203
We present novel means to hyperpolarize deuterium nuclei in 13CD2 groups at cryogenic temperatures. The method is based on cross-polarization from 1H to 13C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by 13C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 12 spins. Although the lifetimes TSTI are shorter than T1(Cz), they can exceed the life-time T1(Dz) of deuterium Zeeman magnetization by a factor of more than 20.
View details for DOI 10.1063/1.4967402
View details for Web of Science ID 000388956900015
View details for PubMedID 27875876
Cross-Correlated Relaxation of Dipolar Coupling and Chemical-Shift Anisotropy in Magic-Angle Spinning R-1 rho NMR Measurements: Application to Protein Backbone Dynamics Measurements
JOURNAL OF PHYSICAL CHEMISTRY B
2016; 120 (34): 8905–13
Transverse relaxation rate measurements in magic-angle spinning solid-state nuclear magnetic resonance provide information about molecular motions occurring on nanosecond-to-millisecond (ns-ms) time scales. The measurement of heteronuclear ((13)C, (15)N) relaxation rate constants in the presence of a spin-lock radiofrequency field (R1ρ relaxation) provides access to such motions, and an increasing number of studies involving R1ρ relaxation in proteins have been reported. However, two factors that influence the observed relaxation rate constants have so far been neglected, namely, (1) the role of CSA/dipolar cross-correlated relaxation (CCR) and (2) the impact of fast proton spin flips (i.e., proton spin diffusion and relaxation). We show that CSA/D CCR in R1ρ experiments is measurable and that the CCR rate constant depends on ns-ms motions; it can thus provide insight into dynamics. We find that proton spin diffusion attenuates this CCR due to its decoupling effect on the doublet components. For measurements of dynamics, the use of R1ρ rate constants has practical advantages over the use of CCR rates, and this article reveals factors that have so far been disregarded and which are important for accurate measurements and interpretation.
View details for DOI 10.1021/acs.jpcb.6b06129
View details for Web of Science ID 000382596700016
View details for PubMedID 27500976
View details for PubMedCentralID PMC5010779