Noncovalent Dimer Formation in Liquid Chromatography–Mass Spectrometry Analysis

[Image: see text] Evidence will be presented that in the article “Novel LC–MS(2) Product Dependent Parallel Data Acquisition Function and Data Analysis Workflow for Sequencing and Identification of Intact Glycopeptides” written by Wu, S.-W.; Pu, T.-H.; Viner, R.; Khoo, K.-H. in Anal. Chem.201486, 5478–548624796651, noncovalent homo- and heterodimers were mis-identified as glycopeptides bearing well-defined N-linked structures, where the unexplained mass was attributed to excessive O-glycosylation. Noncovalent dimer formation of abundant components has not previously been considered as a complication in high-throughput proteomic analyses.