The Use of Label-free Expression Profiling

retention time reproducibility of the Waters nanoACQUITY UPLCTM System, coupled with the elevated resolution and mass measurement accuracy afforded by the Micromass® Q-Tof PremierTM mass spectrometer, which provides the selectivity and specificity necessary to allow ions to be identified and correlated across identically prepared control and experimental sample sets. Waters® Protein Expression System – A novel solution for label-free quantitation in proteomics and biomarker research. INTRODUCTION A common goal of proteomic experiments is the qualitative identification of proteins from biological samples. However, the study of protein expression levels between samples has become increasingly important and several approaches utilizing stable isotope labelling of samples in combination with separation and subsequent analysis by mass spectrometry, have been described [1,2]. In addition, a previous study using an oa-Tof mass spectrometer, in a parallel manner, provided enhanced protein identification in combination with relative protein quantitation via isotope labelling [3]. We have recently presented a concept for qualitative and quantitative protein profiling using LC/MS, without the use of isotope labelling [4]. This strategy allows the relative change in abundance of individual peptides, and proteins, in highly complex mixtures Here we have used this analytical approach to monitor C-reactive protein (CRP) in normal human serum and in serum containing an elevated level of CRP.