Detergents are widely used to improve the solubilization and extraction of hydrophobic membrane proteins in proteomics. Since most detergents are not compatible with subsequent steps of analysis, the removal of detergents from samples, especially those in micro-scale amounts, is a worthy topic of investigation. In this paper, we present a novel polyvinylidene difluoride (PVDF) membrane-mediated sample preparation method for micro-scale membrane proteome analysis, using a rat liver cell membrane-enriched fraction as model material. The proteins in the fraction were extracted in a 2 % sodium dodecyl sulfate (SDS) solution and the protein solution was applied on a piece of PVDF membrane followed by drying and repeated washing in order to remove SDS and other salts. Quantitative determination indicated that about 84% of the SDS in the sample was removed and protein loss was less than 10%. Four methods were used and compared for digesting the proteins adsorbed on PVDF membrane. Dimethyl formamide (DMF)-assisted digestion was the most effective with regard to the identification of membrane proteins, particularly the highly hydrophobic multi-transmembrane proteins. These results demonstrate that PVDF membrane-aided sample cleanup combined with DMF-assisted digestion has potential utility in the micro-scale membrane proteome analysis.
 Blonder J., Goshe M.B., Moore R.J, Pasa-Tolic L., Masselon C.D.,
Lipton M.S, et al., Enrichment of integral membrane proteins for
proteomic analysis using liquid chromatography-tandem mass
spectrometry, J. Proteome Res., 2002, 1, 351-360.
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