There are many different types of PTM, and detection of specific types requires dedicated tailored workflows, often involving more than one MS fragmentation technique within the same sample. Due to the typicaly low levels of post-translationally-modified peptides in complex protein digests, the detection of PTMs often requires enrichment strategies prior to analysis by MS. For example, enrichment strategies such as Titanium dioxide (TiO2) chromatography and Immobilized Metal Affinity Chromatography (IMAC) can be used to separate phosphopeptides from complex peptide mixtures, which improves the detection of phosphorylation sites by MS. NAPI core facilities have extensive experience in such enrichment strategies, and can provide these techniques as a service to core facility users.
New high-end MS instruments purchased through NAPI will enable us to perform more sensitive and accurate detection of well-studied PTMS such as phosphorylation. Additionally, our new MS instruments will enable the analysis of several more PTMs that, despite high scientific interest, have been more difficult to study comprehensively. These include glycosylation, acetylation, methylation, lipidation, and ubiquitin/ubiquitin-like modifications.