Ion-Exchange Sample Displacement Chromatography as a Method for Fast and Simple Isolation of Low- and High-Abundance Proteins from Complex Biological Mixtures

Sample displacement chromatography (SDC) in reversed phase and ion-exchange modes was introduced at the end of 1980s. This chromatographic method was first used for preparative purification of synthetic peptides, and subsequently adapted for protein fractionation, mainly in anion-exchange mode. In the past few years, SDC has been successfully used for enrichment of low- and medium-abundance proteins from complex biological fluids on both monolithic and bulk chromatographic supports. If aqueous mobile phase is used with the application of mild chromatographic conditions, isolated proteins are not denatured and can also keep their biological activity. In this paper, the use of SDC in anion-exchange mode on a high-capacity chromatographic resin for separation of proteins from complex biological mixtures such as human plasma is demonstrated. By use of three and more columns coupled in series during sample application, and subsequent parallel elution of detached columns, additional separation of bound proteins was achieved. Highly enriched human serum albumin fraction and a number of physiologically active medium- and low-abundance proteins could be fractionated and detected by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and matrix assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS). The use of the aforementioned columns that can be sanitized with 1 M sodium hydroxide for further application of SDC in biotechnology and food technology was discussed