Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/58215

Title

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

Author(s)

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

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.

Publication type

Journal article

Source

Langmuir, Vol. 24, no. 9 (May 2008), pp. 4901-4906

Publication year

2008

Keyword(s)

Bilayer surface;  Bis-SorbPC;  Bis-sorbylphosphatidylcholine;  Crosslinking;  G-protein-coupled receptor;  GPCR;  Lipid bilayers;  Mass spectrometry;  Oxidation reduction reaction;  Phosphatidylcholines;  Photopolymerisation;  Pigments;  Polymers;  Redox reactions;  Rhodopsin;  Secondary ion mass spectrometry;  Spectrophotometry;  Surface analysis;  Surface properties;  Vacuum;  X ray photoelectron spectroscopy;  XPS

Publisher

American Chemical Society

ISSN

0743-7463

Publisher URL

http://dx.doi.org/10.1021/la800037r

Copyright

Copyright © 2008 American Chemical Society. Publisher does not officially support author/institution self-archiving of either the post-print (final, revised accepted draft) and/or published version of full text.

Additional information

This work was supported by NIBIB Grant EB-002027 to the National ESCA and Surface Analysis Center for Biomedical Problems (NESAC/BIO), NSF Grant CHE-0518702, NIH Grant EB007047, and NIH Grant EY12049.

Peer reviewed