Assessing human urinary proteome using a mass spectrometry-based profiling system combined with magnetic nanoparticles

Background: Samples originating from body fluids often contain a complex mixture of inorganic salts, buffers, chaotropic agents, surfactant/detergents, preservatives, and other solubilizing agents. The presence of those contaminants often precludes direct analysis by mass spectrometry. Urine, a blood filtrate produced by the urinary system, is an ideal bio-sample and a rich source of biomarkers for diagnostic information. Methods: To enhance our understanding of urinary proteome, the urine proteins were prepared by magnetic nanoparticles (MNPs) combined with MACS separation column system and then identified by reverse phase nano-high performance liquid chromatography electrospray ionization tandem mass spectrometry (RP-nano-HPLC-ESI-MS/MS) followed by peptide fragmentation pattern. Results: Experimental results have revealed that the better protein identification for the demonstration of bovine serum albumin (BSA) in artificial urine. Using this cleanup approach, a total of 542 peptides, corresponding to 282 unique proteins, were identified from human urine samples, in which 54 proteins have higher confidence levels. Indeed, this study has revealed that some biological factors might be increased along with aging, such as up-regulation of immunoproteins. Conclusions: The present study was designed to establish optimal techniques to develop a proteomic map of urinary proteins, and a cleanup method that greatly simplifies this sample preparation process was proposed.