Ionisation bias undermines the use of matrix-assisted laser desorption/ionisation for estimating peptide deamidation: Synthetic peptide studies demonstrate electrospray ionisation gives more reliable response ratios.

ABSTRACT:

Rationale

Although mass spectrometry (MS) is routinely used to determine deamination in peptide mixtures, the effects of the choice of ionisation source have not yet been investigated. In particular, matrix-assisted laser desorption/ionisation (MALDI) has become a popular tool with which to measure levels of glutamine deamidation in ancient proteins. Here we use model synthetic peptides to rigorously compare MALDI and electrospray ionisation (ESI).

Methods

We used two synthetic peptides, with glutamine (Q) in one substituted for glutamic acid (E) in the other, to investigate the suitability of MALDI and ESI sources for the assessment of deamidation in peptides using MS. We also compared measurements of the same Q- and E-containing peptide mixtures using two different mass an

SUBMITTER: Simpson JP 

PROVIDER: S-EPMC6594239 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature