Fig. 4: Microproteins are a class of potential host cell impurity in antibody drug products.
From: Detection of host cell microprotein impurities in antibody drug products
We utilised (a) data from LC-MS/MS-based HCP analyses of 8 antibody-drug products generated in our laboratory as well as a previous study by Pythoud et al. spanning (b) 5 sample preparation methods and captured on (c) 2 types of Orbitrap MS instruments. The DDA MS data was first searched against canonical proteins using MetaMorpheus with spectral mass calibration enabled, resulting in the identification of (d) canonical proteins in each product tested. For microproteins, the PepQuery2 algorithm was used to (e) detect microprotein PSMs. The false positive rate is reduced by PepQuery2 by statistical evaluation against randomly shuffled sequences (i.e. PepQuery p-value) and an unrestricted modification search against known proteins. We identified (d) 40 microproteins with (f) 28 microproteins found in more than one drug product. Note: The number of microproteins detected for each sample preparation method employed in the Pythoud et al. study is shown in Supplementary Fig. 8. Source data are provided as a Source Data file. Panels a and c created with BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license.
