Studying lipid-protein interactions with electron paramagnetic resonance spectroscopy of spin-labeled lipids

Tibor Pali, Zoltan Kota

Research output: Chapter in Book/Report/Conference proceedingChapter

2 Citations (Scopus)

Abstract

Spin label electron paramagnetic resonance (EPR) of lipid-protein interactions reveals crucial features of the structure and assembly of integral membrane proteins. Spin label EPR spectroscopy is the technique of choice to characterize the protein-solvating lipid shell in its highly dynamic nature, because the EPR spectra of lipids that are spin labeled close to the terminal methyl end of their acyl chains display two spectral components, those corresponding to lipids directly contacting the protein and those corresponding to lipids in the bulk fluid bilayer regions of the membrane. In this chapter, typical spin label EPR procedures are presented that allow determination of the stoichiometry of interaction of spin-labeled lipids with the intra-membranous region of membrane proteins or polypeptides, as well as the association constant of the spin-labeled lipid with respect to the host lipid. The lipids giving rise to the so-called immobile spectral component in the EPR spectrum of such samples are identified as the motionally restricted first-shell lipids solvating membrane proteins in biomembranes. Stoichiometry and selectivity are directly related to the structure of the intra-membranous sections of membrane-associated proteins or polypeptides and can be used to study the state of assembly of such proteins in the membrane. Since these characteristics of lipid-protein interactions are discussed in detail in the literature [see Marsh (Eur Biophys J 39: 513-525, 2010) for a most recent review], here we focus more on how to spin label model and biomembranes and how to measure and analyze the two-component EPRspectra of spin-labeled lipids in phospholipid bilayers that contain proteins or polypeptides. After a description of how to prepare spin-labeled model and native biological membranes, we present the reader with computational procedures for determining the molar fraction of motionally restricted lipids when both, one, or none of the pure isolated-mobile or immobile-spectral components are available. With these topics, this chapter complements a recent methodological paper [Marsh (Methods 46: 83-96, 2008)]. The interpretation of the data is discussed briefly, as well as other relevant and recent spin label EPR techniques for studying lipid-protein interactions, not only from the point of view of lipid chain dynamics.

Original languageEnglish
Title of host publicationLipid-Protein Interactions
Subtitle of host publicationMethods and Protocols
PublisherHumana Press Inc.
Pages297-328
Number of pages32
ISBN (Print)9781627032742
DOIs
Publication statusPublished - 2013

Publication series

NameMethods in Molecular Biology
Volume974
ISSN (Print)1064-3745

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Keywords

  • Annular
  • Electron paramagnetic resonance (EPR)
  • Electron spin resonance (ESR)
  • Immobile and mobile membrane lipids
  • Integral membrane proteins
  • Lipid-protein interactions
  • Motionally restricted and bulk lipids
  • Phospholipids
  • Solvation
  • Spin label
  • Spin-labeled
  • Two-component spectrum

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics

Cite this

Pali, T., & Kota, Z. (2013). Studying lipid-protein interactions with electron paramagnetic resonance spectroscopy of spin-labeled lipids. In Lipid-Protein Interactions: Methods and Protocols (pp. 297-328). (Methods in Molecular Biology; Vol. 974). Humana Press Inc.. https://doi.org/10.1007/978-1-62703-275-9_14