Mass Spectroscopy Used to Screen Serum for Biomarkers

Researchers have developed a new technique for identifying rare proteins in blood serum that may assist in efforts to identify biomarkers for cancer and other diseases.

The problem with most methods for analyzing serum proteins is that techniques to remove abundant proteins usually result in the removal of rare proteins as well. To get around this problem, investigators at the U.S. National Cancer Institute (Frederick, MD, USA) utilized conventional separation techniques combined with tandem mass spectrometry (MS/MS). Serum proteins were digested with trypsin and resolved into 20 fractions by ampholyte-free liquid phase isoelectric focusing. These 20 peptide fractions were further fractionated by strong cation-exchange chromatography, each of which was analyzed by microcapillary reversed-phase liquid chromatography coupled online with MS/MS analysis.

Results published in the June 2004 issue of Clinical Proteomics revealed that human serum contains 1,444 unique peptides. "Our investigation resulted in the identification of 1,444 proteins in serum,” said senior author Dr. Thomas Conrads, associate director of the Mass Spectrometry Center at the National Cancer Institute. "The proteins identified by earlier research overlapped only slightly with those characterized by our group. This emphasizes the wide scope and complexity of the human serum proteome, which has been estimated to contain more than 10,000 proteins. The next step will be to apply what has been learned and developed in this study to identify disease-specific biomarkers with greater positive predictive value than those presently being used for diagnostic purposes.”

The investigators have created a publicly available database of the newly identified human serum peptides. It can be accessed at http://bpp.nci.nih.gov/



Related Links:
National Cancer Institute