Ultra-high vacuum surface analysis study of rhodopsin incorporation into supported lipid bilayers

Roger Michel, Varuni Subramaniam, Sally L. McArthur, Bruce Bondurant, Gemma D. D'Ambruoso, Henry K. Hall, Michael F. Brown, Eric E. Ross, S. Scott Saavedra, David G. Castner

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Planar supported lipid bilayers that are stable under ambient atmospheric and ultra-high-vacuum conditions were prepared by cross-linking polymerization of bis-sorbylphosphatidylcholine (bis-SorbPC). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to investigate bilayers that were cross-linked using either redox-initiated radical polymerization or ultraviolet photopolymerization. The redox method yields a more structurally intact bilayer; however, the UV method is more compatible with incorporation of transmembrane proteins. UV polymerization was therefore used to prepare cross-linked bilayers with incorporated bovine rhodopsin, a light-activated, G-protein-coupled receptor (GPCR). A previous study (Subramaniam, V.; Alves, I. D.; Salgado, G. F. J.; Lau, P. W.; Wysocki, R. J.; Salamon, Z.; Tollin, G.; Hruby, V. J.; Brown, M. F.; Saavedra, S. S. J. Am. Chem. Soc. 2005, 127, 5320-5321) showed that rhodopsin retains photoactivity after incorporation into UV-polymerized bis-SorbPC, but did not address how the protein is associated with the bilayer. In this study, we show that rhodopsin is retained in supported bilayers of poly(bis-SorbPC) under ultra-high-vacuum conditions, on the basis of the increase in the XPS nitrogen concentration and the presence of characteristic amino acid peaks in the ToF-SIMS data. Angle-resolved XPS data show that the protein is inserted into the bilayer, rather than adsorbed on the bilayer surface. This is the first study to demonstrate the use of ultra-high-vacuum techniques for structural studies of supported proteolipid bilayers.

Original languageEnglish (US)
Pages (from-to)4901-4906
Number of pages6
JournalLangmuir
Volume24
Issue number9
DOIs
StatePublished - May 6 2008

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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    Michel, R., Subramaniam, V., McArthur, S. L., Bondurant, B., D'Ambruoso, G. D., Hall, H. K., Brown, M. F., Ross, E. E., Saavedra, S. S., & Castner, D. G. (2008). Ultra-high vacuum surface analysis study of rhodopsin incorporation into supported lipid bilayers. Langmuir, 24(9), 4901-4906. https://doi.org/10.1021/la800037r