Tissue Mild Extraction Enriches Membrane, Cytoplasmic, and Secreted Proteomes for Biomarker Discovery.

Clinical blood biomarkers provide important diagnostic information and are generally secreted, cytoplasmic, membrane, and other soluble proteins. However, in the mass spectrometry-based proteomic biomarker discovery phase, the whole tissue is often lysed directly for analysis, and this increases protein complexity in the sample, limiting the detection of soluble proteins as biomarkers. Here, we use a mild extraction method that includes a low salt buffer and 1% Triton X-100 to isolate proteins from mouse tissues followed by proteomic analyses.

PEG Precipitation Followed by Albumin Depletion for Plasma Proteomics Analysis.

The mass spectrometry (MS)-based blood plasma or serum proteomic analysis is limited by interference from albumin, immunoglobins, and other highly abundant proteins. We have found that poly(ethylene glycol) (PEG) can efficiently precipitate some of these proteins except albumin. By PEG precipitation followed by albumin depletion, additional proteins and -glycoproteins can be identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the plasma.