Systematic Evaluation of Data-Independent Acquisition for Sensitive and Reproducible Proteomics – a Prototype Design for a Single Injection Assay

摘要

Data-independent acquisition (DIA) based proteomics has become increasingly complicated in recent years due to the vast number of workflows described, coupled with a lack of studies indicating a rational framework for selecting effective settings to use. To address this issue and provide a resource for the proteomics community, we compared twelve DIA methods that assay tryptic peptides using various mass-isolation windows. Our findings indicate the most sensitive single injection LC-DIA method uses 6 m/z isolation windows to analyze the densely populated tryptic peptide range from 450–730 m/z, which allowed quantification of 4,465 E. coli peptides. In contrast, using the sequential windowed acquisition of all theoretical fragment-ions (SWATH) approach with 26 m/z isolation windows across the entire 400–1200 m/z range, allowed quantification of only 3,309 peptides. This reduced sensitivity with 26 m/z windows is caused by an increase in co-eluting compounds with similar precursor values detected in the same tandem MS spectra, which lowers the signal-to-noise of peptide fragment-ion chromatograms and reduces the amount of low abundance peptides that can be quantified from 410–920 m/z. Above 920 m/z, more peptides were quantified with 26 m/z windows due to substantial peptide ¹³C isotope distributions that parse peptide ions into separate isolation windows. Since reproducible quantification has been a long-standing aim of quantitative proteomics, and is a so-called trait of DIA, we sought to determine whether precursor-level chromatograms used in some methods rather than their fragment-level counterparts have similar precision. Our data show extracted fragmention chromatograms are the reason DIA provides superior reproducibility.