Many More Proteins Found in Blood Serum

Investigators using advanced chromatographic techniques have identified or confirmed 490 proteins in human blood serum — nearly doubling the number of known serum proteins. Their findings were reported in the December 2002 issue of Molecular and Cellular Proteomics.

The researchers, from the Department of Energy's Pacific Northwest National Laboratory (Richland, WA, USA), removed immunoglobulins from serum using proteins A and G and then digested the remaining proteins with trypsin. Resulting peptides were separated by strong-cation exchange chromatography into distinct fractions prior to analysis by online reversed-phase microcapillary liquid chromatography coupled with ion trap mass spectrometry. This separation resulted in a three-to-five fold increase in the number of proteins detected in an individual serum sample. This increase in the number of proteins permitted detection of lower abundance serum proteins (ng/ml range) including human growth hormone, interleukin-12, and prostate-specific antigen.

"We have performed the most extensive identification of proteins in serum to date,” said Dr. Joel Pounds, corresponding author and a Pacific Northwest National Laboratory staff scientist. "We studied blood serum because it holds clues to all the major processes in our bodies. We need to know what proteins exist in that serum to know how they might be used to predict disease susceptibility, monitor disease progression, or diagnose disease. With this study, we have taken a large step toward defining the protein composition of serum, but many more steps and technological improvements are needed to move beyond these 490 proteins to the thousands of proteins that may be present in blood serum.”




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Pacific Northwest National Laboratory