Simple and Sensitive Analysis for Dried Blood Spot Proteins by Sodium Carbonate Precipitation for Clinical Proteomics

Dried blood spots (DBS) are widely used for screening biomolecular profiles, including enzymatic activities. However, detection of minor proteins in DBS by liquid chromatography-mass spectrometry (LC-MS/MS) without pre-enrichment remains challenging because of the coexistence of large quantities of hydrophilic proteins. In this study, we address this problem by developing a simple method using sodium carbonate precipitation (SCP). SCP enriches hydrophobic proteins from DBS, allowing substantial removal of soluble proteins. In combination with SCP, we used quantitative LC-MS/MS proteome analysis in a data-independent acquisition mode (DIA) to enhance the sensitivity and quantification limits of proteome analysis. As a result, identification of 1977 proteins in DBS is possible, including 585 disease-related proteins listed in the Online Mendelian Inheritance in Man.