Solid State ²H NMR Spectroscopy Analysis of Lipid-Protein Interactions in Response to Bilayer Deformations: Development of Methodology

Abstract

Using solid-state 2H NMR spectroscopy, one can obtain de-convoluted NMR spectra which can then be used to evaluate segmental order parameters. These order parameters describe the motional averaging of C - ²H segments with respect to the bilayer normal, and are therefore related to bilayer structural parameters such as the mean area per lipid and the volumetric bilayer thickness. From this type of data, the effect of various stresses (hydration pressure, osmotic stress) on the lipid bilayer can be quantified. This type of analysis has been made with DMPC-d₅₄ as the lipid sample and polyethylene glycol (PEG) of molecular weight 1500 (PEG 1500) as the osmolyte. We plan to extend this work with other lipid systems like POPC and osmolytes such as PEG 8000 in order to provide more varied data in terms of sample identity. The long-term goal is to provide enough experimental data on various lipid samples to be able to make a qualitative analysis on how bilayer deformation influences non-specific lipid-protein interactions. This paper develops the methodology for the data reduction and analysis procedures used in our analysis of these lipid samples, while demonstrating the applicability of solid-state ²H NMR spectroscopy in investigating structural properties of lipid bilayers.