Adsorption of Urinary Proteins on the Conventionally Used Urine Collection Tubes: Possible Effects on Urinary Proteome Analysis and Prevention of the Adsorption by Polymer Coating
Figure 2
Representative spectra of the MALDI-TOF MS of urinary proteins and/or peptides adsorbed on urinary tubes with and without poly(MPC-co-BMA) coating (a) and those of urine samples kept in the coated and noncoated tubes (b). (a) Left: it was notable that 2556 m/z and 2645 m/z peaks were observed in proteinuric samples only when obtained from the poly(MPC-co-BMA) non-coated tubes (the upper panel). Similar results were obtained in 7 different experiments. Right: the two peaks detectable in noncoated tubes were significantly attenuated in poly(MPC-co-BMA)-coated tubes (P < 0.001). (b) When urinary samples were kept in the coated and uncoated urine tubes, relative peak intensities of the 2556 m/z and 2645 m/z peaks were attenuated in poly(MPC-co-BMA)-coated tubes (the upper panel), which was confirmed by the quantitative study using the internal standard (2556 m/z; P < 0.007, 2653 m/z; P < 0.014).
