Urine Sample Preparation and Protein Profiling by Two-Dimensional Electrophoresis and Matrix-Assisted Laser Desorption Ionization Time of Flight Mass

Urine represents the most easily attainable and consequently one of the most common samples in clinical analysis and diagnostics. However, urine is also considered one of the most difficult proteomic samples to work with due to its highly variable contents, as well as the presence of various proteins in low abundance or modified forms. In this chapter, we describe simple protocols and troubleshooting tips for urinary protein preparation and profiling by two-dimensional electrophoresis or directly via matrix-assisted laser desorption ionization time of flight mass spectroscopy. Direct dilution, protein precipitation, ultrafiltration, and solid phase extraction in combination to the above profiling technologies serve the means for reliable proteomics analysis of one of the most significant yet very complex biological samples.