PASS-DIA: A novel data-independent acquisition approach for discovery studies

We present a strategy termed PASS-DIA (Precursor ion And Small Slice-DIA) in which MS/MS spectra are acquired with small isolation window (slices) and MS/MS spectra are interpreted with accurately measured precursor ion masses. This method enables direct application of conventional spectrum-centric analysis pipelines for peptide identification and precursor ion-based quantitation. The performance of PASS-DIA was superior to both DDA and conventional DIA experiment with regard to identification of peptides. Application of PASS-DIA for analysis of samples with post-translationally modified peptides such as phosphorylation and N-glycosylation again revealed its superior performance. Finally, use of PASS-DIA to characterize a rare proteome of human fallopian tube organoid samples revealed biologically relevant and low abundance proteins. Overall, PASS-DIA is a novel DIA approach for use as a discovery tool which outperforms both conventional DDA and DIA experiments to provide additional protein information. We believe that PASS-DIA method could become an important strategy for discovery type studies when deeper proteome characterization is required.