Enrichment of low-abundance brain proteins by preparative electrophoresis.

Detection of low-copy-number gene products is essential for the development of novel drugs, however, it represents a major drawback of proteomics and simultaneously a scientific challenge. We studied the enrichment of rat brain cytosolic proteins by preparative electrophoresis using the PrepCell apparatus. The electrophoresis was performed in the presence of 0.1% lithium dodecyl sulfate. The proteins eluted from the gel were analyzed by two-dimensional gel electrophoresis and identified by matrix-assisted laser desorption ionization mass specrometry. Lithium dodecyl sulfate was easily exchanged against agents compatible with isoelectric focusing. Low-abundance proteins, which had not been found before, including neuronal-specific and calcium-binding proteins, were detected. In particular, low-molecular-mass proteins, such as hippocalcin, visinin-like proteins, and 14-3-3 proteins were strongly enriched by preparative electrophoresis.