Improved disc SDS-PAGE for extraction of low molecular weight proteins from serum.

The low molecular weight proteins can provide a lot of valuable information of biomarkers. To study these proteins, the high abundance and high molecular weight proteins must be removed prior to analysis. In this work, a simple and inexpensive disc SDS-PAGE to extract low molecular weight proteins from human serum and cutoff proteins larger than 30 kDa was developed. Some experimental conditions were examined. The experimental results obtained by plate SDS-PAGE and MALDI-TOF MS showed that the molecular weight of extracted proteins was about in the range from 0.3 to 28 kDa. Some experiments, including precipitation of proteins in organic solvents, SPE and cytochrome C test, were carried out and the experimental results demonstrated successful recovery of proteins/peptides with molecular weight from several hundreds of dalton to about 30 kDa. The experimental results obtained by plate SDS-PAGE indicated the repeatability was satisfactory.