Ultra-thin layer MALDI mass spectrometry of membrane proteins in nanodiscs

Michael T. Marty, Aditi Das, Stephen G. Sligar

Research output: Contribution to journalArticlepeer-review

Abstract

Nanodiscs have become a leading technology to solubilize membrane proteins for biophysical, enzymatic, and structural investigations. Nanodiscs are nanoscale, discoidal lipid bilayers surrounded by an amphipathic membrane scaffold protein (MSP) belt. A variety of analytical tools has been applied to membrane proteins in nanodiscs, including several recent mass spectrometry studies. Mass spectrometry of full-length proteins is an important technique for analyzing protein modifications, for structural studies, and for identification of proteins present in binding assays. However, traditional matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry methods for analyzing full-length membrane proteins solubilized in nanodiscs are limited by strong signal from the MSP belt and weak signal from the membrane protein inside the nanodisc. Herein, we show that an optimized ultra-thin layer MALDI sample preparation technique dramatically enhances the membrane protein signal and nearly completely eliminates the MSP signal. First-shot MALDI and MALDI imaging are used to characterize the spots formed by the ultra-thin layer method. Furthermore, the membrane protein enhancement and MSP suppression are shown to be independent of the type of membrane protein and are applicable to mixtures of membrane proteins in nanodiscs. [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)721-729
Number of pages9
JournalAnalytical and bioanalytical chemistry
Volume402
Issue number2
DOIs
StatePublished - Jan 2012

Keywords

  • Cytochrome P450 3A4
  • Cytochrome p450 reductase
  • MALDI-TOF mass spectrometry
  • Membrane proteins
  • Nanodisc
  • Rhodopsin

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry

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