Analysis of Rat Liver Proteins by Peptide Immobilized pH Gradient Isoelectric Focusing Combined with Liquid Chromatography-Tandem Mass Spectrometry

Abstract Due to the complexity of the biological sample, it is important to develop an effective pre-separation method for the liquid chromatography-mass spectrometer (LC-MS) analysis of biological samples. In this experiment, enzymatic hydrolysate of rat liver protein was pre-separated by peptide immobilized pH gradient isoelectric focusing (IPG-IEF) method, and the pre-separated components were further separated by reversed physe liquid chromatography (RPLC) and then identified by LTQ-Orbitrap MS. A total of 2039 kinds of proteins were identified, including 18 kinds of acetylated proteins, 4 kinds of proteins which were never reported before. Next, bioinformatic analysis was carried out for these proteins. The results showed that peptide IPG-IEF coupled with LC-MS/MS is an effective technique for proteomics analysis and this method is suitable for large-scale protein identification.