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

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.

As seen in the figure, the rat liver proteins participated in biological processes such as metabolism, localization, biosynthesis, transport, stress response, decomposition, cell cycle and cell apoptosis. The proteins involved in metabolism account for 35%. Liver is the major organ of metabolism. The results also indicated that the liver proteins were mainly involved in the metabolic processes.Figure optionsDownload as PowerPoint slide