SWATH Mass Spectrometry Performance Using Extended Peptide MS/MS Assay Libraries.

Area of Science:

• Proteomics
• Mass Spectrometry
• Bioinformatics

Background:

• Data-independent acquisition (DIA) methods like SWATH-MS in proteomics rely on peptide MS/MS assay libraries for accurate peptide identification and quantification.
• Currently, assay libraries are generated locally or sourced from repositories, but their impact on SWATH-MS performance is not systematically evaluated.

Purpose of the Study:

• To systematically evaluate the effect of different assay libraries on SWATH-MS performance.
• To develop a computational workflow, SwathXtend, for generating extended peptide assay libraries and performing statistical analysis of quantitative comparisons.

Main Methods:

• Developed SwathXtend workflow to integrate local seed libraries with external data.
• Created test samples by spiking yeast peptides into human K562 cell lysate peptides at varying ratios.
• Assessed SWATH-MS performance using local and external assay libraries of diverse compositions and complexities.

Main Results:

• Integrating local seed libraries with external assay libraries significantly improved the number of identified peptides and proteins compared to using local libraries alone.
• The performance of extended assay libraries was influenced by the MS/MS feature similarity between seed and external libraries.
• Employing multiple testing corrections enhanced the statistical rigor for analyzing large, extended assay libraries.

Conclusions:

• Extended peptide assay libraries, particularly those combining local and external data, enhance SWATH-MS performance in proteomics.
• MS/MS feature similarity is crucial for effective library extension.
• Robust statistical analysis is essential for reliable quantification when using extensive assay libraries.