Project Details
Projekt
Overhauser Dynamic Nuclear Polarization at high magnetic fields (9.4 T) on Lipid Bilayers
Subject Area
Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
Term
since 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 405972957
The prolongation of this project aims to establish a quantitative link between the OE-DNP experi-ments with lipid bilayers containing spin-labeled lipids measured in the first period of this project, and the underlying molecular motions that give rise to these experimental results. While the re-ported DNP and cw-EPR experiments provide valuable hints about the nature and dynamics of the local environments surrounding the spin labels, interpreting the experiments in terms of the mo-tions of the lipids and the water molecules is difficult. To provide such an interpretation, we will perform atomistic molecular dynamics (MD) simulations of several lipid-bilayer systems with em-bedded spin-labeled lipids. The MD trajectories will be subjected to two types of quantitative anal-yses that will allow for direct comparison with the reported experiments. First, the dynamics of the spin labels from the simulations will be used to calculate multi-frequency cw-EPR spectra. Second, the dynamics of the vector pointing from an electron spin to a proton spin will be used to calculate the spectral density function of the dipolar interaction between the spins, from which an OE-DNP coupling factor will be obtained. An eventual agreement between the calculations and the experi-ments will shed light on the molecular factors on which the high-field OE-DNP enhancements rely. A possible disagreement between the experiments and the calculations, on the other hand, will illuminate latent deficiencies in the MD simulations. Additionally, we want to extend our 1H Over-hauser DNP experiments on lipid bilayers to DOPC lipids. This will allow exploring if the length mismatch between the spin-labeled lipids with the formerly studied DMPC lipids could be respon-sible for the experimental observed low position dependence of the DNP efficiency by causing structural disorder or changing the accessibility and dynamics of internal water molecules.
DFG Programme
Research Grants
