Preprints
https://doi.org/10.5194/mr-2022-19
https://doi.org/10.5194/mr-2022-19
 
08 Nov 2022
08 Nov 2022
Status: this preprint is currently under review for the journal MR.

Time-domain R-PDLF NMR for molecular structure determination in complex lipid membranes

Anika Wurl, Kay Saalwächter, and Tiago Mendes Ferreira Anika Wurl et al.
  • NMR group, Institute for Physics, Martin Luther University Halle-Wittenberg

Abstract. Proton-detected local field (PDLF) NMR spectroscopy, using magic-angle spinning and dipolar recoupling, is presently the most powerful experimental technique to obtain atomistic structural information from small molecules undergoing anisotropic motion such as peptides, drugs, or lipids in model membranes. The accuracy of the measurements on complex systems is however compromised by the number of transients required and by the difficulty of fitting experimental data due to the omnipresent RF spatial inhomogeneity in NMR probes. Here, we present a new methodology to analyse R-type PDLF NMR experiments that brings a significant improvement of accuracy and that enables to address more complex systems. The new methodology consists of fitting the time-domain data with NMR simulations accounting for RF spatial inhomogeneity, making it possible (1) to use shorter experiments which enables to measure samples with lower material content and prevents RF-heating, (2) to measure smaller C–H bond order parameter magnitudes, |SCH|, and smaller variations of |SCH| upon perturbations of the system and (3) to determine |SCH| values with small differences from distinct sites having the same chemical shift. The increase in accuracy is demonstrated by comparison with 2H NMR quadrupolar echo experiments on mixtures of deuterated and non-deuterated dimyristoylphosphatidylcholine (DMPC). The methodology presented enables an unprecedented level of structural detail and will be highly useful for investigating complex membrane systems as illustrated with membranes composed of a brain lipid extract with many distinct lipid types.

Anika Wurl et al.

Status: open (until 11 Dec 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on mr-2022-19', Anonymous Referee #1, 20 Nov 2022 reply

Anika Wurl et al.

Anika Wurl et al.

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Short summary
R-PDLF NMR spectroscopy is a powerful method to obtain molecular structural information from biological membrane models. However, the conventional analysis of the experiments relies on a Fourier transform in the indirect time domain preventing its application to complex samples. We propose a new methodology, namely to fit the indirect time-domain with simulations that account for RF inhomogeneity, making possible to study far more complex biological membranes than what has been done previously.