Solid-state 2H NMR studies of water- mediated lipid membrane deformation

Trivikram R. Molugu, Xiaolin Xu, Soohyun Lee, K. J. Mallikarjunaiah, Michael F Brown

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Scopus citations

Abstract

The application of solid-state 2H nuclear magnetic resonance (NMR) spectroscopy gives a powerful approach for investigating hydration-mediated effects on lipid bilayer structure and dynamics. The extent to which lipid bilayers are deformed by dehydration stress is inherent to understanding how lipid-protein interactions affect biomembrane functioning. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Structural quantities, such as the area per lipid and volumetric bilayer thickness, are obtained by a mean-torque analysis of 2H NMR order parameters. Removal of water in the liquid-crystalline state gives a reduction of the mean area per lipid, together with a corresponding increase in volumetric bilayer thickness. Measurements of order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Furthermore, solid-state 2H NMR relaxation rates of lipid bilayers at varying hydration levels afford new insights into the role of water in membrane structural dynamics and viscoelastic properties. Model-free interpretation of spinlattice (R1Z) and transverse (RQE 2) relaxation rates suggests that collective chain motions described as order-director fluctuations dominantly contribute to the relaxation. In a continuum picture, elastic deformations in such materials are collective hydrodynamic phenomena with motional time scales spanning many decades (picoseconds to seconds). The dynamic processes mainly affecting the spin-spin relaxation have characteristic time scales much longer than those contributing to spin-lattice relaxation. Such studies probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions, giving a unique source of information about intermolecular forces pertinent to biomembrane structure and function.

Original languageEnglish (US)
Title of host publicationModern Magnetic Resonance
PublisherSpringer International Publishing
Pages1225-1250
Number of pages26
ISBN (Electronic)9783319283883
ISBN (Print)9783319283876
DOIs
Publication statusPublished - Jun 13 2018

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Keywords

  • Lipid bilayers
  • Liquid crystals
  • Membrane elasticity
  • Membranes deformation
  • Molecular dynamics
  • NMR relaxation
  • NMR spectroscopy
  • Order-director fluctuations
  • Osmotic stress

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Medicine(all)
  • Social Sciences(all)
  • Arts and Humanities(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Molugu, T. R., Xu, X., Lee, S., Mallikarjunaiah, K. J., & Brown, M. F. (2018). Solid-state 2H NMR studies of water- mediated lipid membrane deformation. In Modern Magnetic Resonance (pp. 1225-1250). Springer International Publishing. https://doi.org/10.1007/978-3-319-28388-3_143