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A high-throughput approach reveals distinct peptide charging behaviors in electrospray ionization mass spectrometry

ABSTRACT: Electrospray ionization is a powerful and prevalent technique used to ionize analytes prior to measurement through mass spectrometry. The distribution of charges that an analyte receives (charge state distribution, CSD) is an important consideration for interpreting the mass spectra and for identifying analytes. However, due to an incomplete understanding of the ionization mechanism, the analyte properties that influence CSDs are not fully understood. Here, we employ a machine learning-based high-throughput approach and analyze CSDs of hundreds of thousands of peptides. We find that half of the peptides exhibit charges that differ from what one would naively expect (number of basic sites). Moreover, these peptides can be classified into two regimes---undercharging and overcharging---and that these two regimes display markedly different charging characteristics. Strikingly, peptides in the overcharging (but not undercharging) regime show minimal dependence on basic site count, and more generally, the two regimes exhibit distinct sequence determinants. These findings highlight the rich ionization behavior of peptides and the potential of CSDs for enhancing peptide identification.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Oded Regev Marko Jovanovic

PROVIDER: MSV000091473 | MassIVE | Sun Mar 12 17:03:00 GMT 2023

SECONDARY ACCESSION(S): PXD040794

REPOSITORIES: MassIVE

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