Fractionation of Soluble Proteins Using DEAE-Sepharose, SP-Sepharose, and Phenyl Sepharose Chromatographies for Proteomics.

In order to simplify a complex mixture of soluble proteins from tissues, a protocol to fractionate samples prior to two-dimensional (2D) gel electrophoresis has been developed. These methods involve the use of DEAE-Sepharose, SP-Sepharose, and phenyl Sepharose chromatographic columns and the fractionation of the protein mixtures based on differential anionic, cationic, and hydrophobic properties of the proteins, respectively. Fractionation of the soluble proteins with DEAE-Sepharose can result in an increase in the number of detectable 2D gel spots. These gel spots are amenable to protein identification by using in-gel trypsin digestions, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and peptide mass fingerprinting. The DEAE-Sepharose column fractionation acts to partition soluble proteins from cell extracts. Similarly, a SP-Sepharose column can fractionate soluble proteins and increase the number of detectable gel spots. Lastly, fractionation of cell extract with a phenyl Sepharose column can also result in an increase in the number of detectable 2D gel spots. This chapter describes an easy, inexpensive way to fractionate soluble proteins and a way to better profile proteomes.