biostudies-literatureUnknown8(11)Bomans KBiotherapeutics are often produced in non-human host cells like Escherichia coli, yeast, and various mammalian cell lines. A major focus of any therapeutic protein purification process is to reduce host cell proteins to an acceptable low level. In this study, various E. coli host cell proteins were identified at different purifications steps by HPLC fractionation, SDS-PAGE analysis, and tryptic peptide mapping combined with online liquid chromatography mass spectrometry (LC-MS). However, no host cell proteins could be verified by direct LC-MS analysis of final drug substance material. In contrast, the application of affinity enrichment chromatography prior to comprehensive LC-MS was adequate to identify several low abundant host cell proteins at the final drug substance level. Bacterial alPloS onee81639https://www.ebi.ac.uk/biostudies/studies/S-EPMC3842259biostudies-literatureIdentification and monitoring of host cell proteins by mass spectrometry combined with high performance immunochemistry testing.PMC3842259Roedl VMolhoj MEberl GReusch DWiedmann MDiepold KSchmalz CWegele HStrauss ULang AAdolf LVogel RBomans KKyriosoglou KBulau PfalseIdentification and monitoring of host cell proteins by mass spectrometry combined with high performance immunochemistry testing.Biotherapeutics are often produced in non-human host cells like Escherichia coli, yeast, and various mammalian cell lines. A major focus of any therapeutic protein purification process is to reduce host cell proteins to an acceptable low level. In this study, various E. coli host cell proteins were identified at different purifications steps by HPLC fractionation, SDS-PAGE analysis, and tryptic peptide mapping combined with online liquid chromatography mass spectrometry (LC-MS). However, no host cell proteins could be verified by direct LC-MS analysis of final drug substance material. In contrast, the application of affinity enrichment chromatography prior to comprehensive LC-MS was adequate to identify several low abundant host cell proteins at the final drug substance level. Bacterial al2013-01-01T00:00:00Z20132026-04-07T19:26:54.394Z2019-03-26T23:17:07ZS-EPMC38422592431233010.1371/journal.pone.0081639