Peptide mapping of proteins in cerebrospinal fluid utilizing a rapid preparative two-dimensional electrophoretic procedure and matrix-assisted laser desorption/ionization mass spectrometry.

A quick two-step procedure involving liquid phase isoelectric focusing in the Rotofor cell in combination with electroelution in the Mini whole cell gel eluter has been used for purification of proteins from human cerebrospinal fluid (CSF). Fractions, each highly enriched in a single protein band and virtually free of other proteins, were selected for characterization by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS). Six CSF proteins, transferrin, alpha1-acid-glycoprotein, Zn-alpha2-glycoprotein, apolipoprotein A1, apolipoprotein E and beta-trace were identified by MALDI-TOFMS analysis of the tryptic digests. These results demonstrate that the combination of liquid phase IEF and electroelution is a rapid preparative two-dimensional separation which can provide single proteins of high purity, in yields sufficient for characterization by MALDI-TOFMS. Characterization of such brain-specific proteins in CSF will be useful in the investigation of the pathophysiology of different brain disorders.