Isomerization and epimerization are abundant, spontaneous chemical modifications occurring in long-lived proteins. These modifications can have important consequences in terms of protein structure, function, and degradation, but they are also difficult to detect. Recent advances in mass spectrometry have enabled more comprehensive identification of isomerized and epimerized peptides than was previously possible, but site-specific identification of modified residues remains challenging. Previous work has shown promise in the use of ion mobility, in conjunction with fragmentation, for site-specific identification of modified sites in epimerized neuropeptides. Here we apply this method, in conjunction with dissociation abundance to explore both identification and site-specific localization of isomerization and epimerization sites in peptides derived from long-lived proteins. Results exploring the most abundant sites including epimerization of serine and all four isomers of aspartic acid will be discussed. The relationship between shifts in drift time and dissociation intensity will also be explored.<br/>

Pinpointing isomerization sites in long-lived proteins using IMS-MS

2019 Fall National Meeting

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