Comparative 2-DE proteomic analysis clarified that the stability of ITIH-4 is decreased under the storage at 4°C

Studies on blood plasma proteome were performed by two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) using samples supplied from China and the United States by collaborations of Human Plasma Proteome Project of HUPO. The plasma proteins were separated by isoelectric focusing using capillary type polyacrylamide gel (PAG) with carrier ampholytes pH 3.5-10 in the first dimension and with SDS-PAGE using 15%, 12.5% and 8% gel in the second dimension. The protein spots were identified by peptide mass fingerprinting using electrospray ionization MS/MS (LC/MSD Trap XCT, Agilent). More than 145 protein spots were identified by LC-MS/MS. The 2-DE patterns showed that the samples stored at 4°C for 3 days lost inter-alpha-trypsin inhibitor heavy chain 4 (ITIH-4).