A Simple Serum Depletion Method For Proteomics Analysis

Serum is the body fluid most often used in biomarker discovery. Albumin, the most abundant serum protein, contributes approximately 50% of the serum protein content, with an additional dozen abundant proteins dominating the rest of the serum proteome. To profile this challenging protein mixture by proteomics, the abundant proteins must be depleted to allow for detection of the low-abundant proteins, the primary biomarker targets. Current serum depletion approaches for proteomics are costly and relatively complex to couple with protein digestion. We demonstrate a simple, affordable serum depletion methodology that, within a few minutes of processing, results in two captured serum fractions - albumin-depleted and albumin-rich - which are digested in situ. We believe our method is a useful addition to the biomarker sample preparation toolbox.METHOD SUMMARY We describe a method for simple albumin depletion by serum fractionation coupled with proteomics analysis. The method is based on selective protein adsorption to quartz under basic conditions. While many serum proteins are captured and can subsequently be eluted, albumin and some other proteins are not retained and pass through the quartz trap. The flow-through albumin-rich fraction is diluted with methanolic ammonium acetate solution and captured in a second quartz trap. Both fractions are digested in situ for proteomics analysis.