Figure 38.

Ion mobility–mass spectrometry (IM-MS) workflow for regiochemistry analysis of N-acetylneuraminic acid (Neu5Ac) linkages in a1-proteinase inhibitor (A1PI). (A) A1PI isolated from human plasma and recombinantly expressed in Chinese hamster ovary (CHO) cells was purified and digested with trypsin, and the glycopeptides were HILIC-enriched. (B) Fragmentation of the obtained glycopeptides and subsequent IM-MS analysis of the characteristic B₃-trisaccharide fragments (m/z 657) enabled the differentiation of α2,3- from α2,6-linked Neu5Ac. The observed fragment drift times and ^TWCCS_N2 are independent of the underlying precursor sequence. Reprinted from ref (590). Published by The Royal Society of Chemistry. Copyright 2016 Hinneburg et al. (Creative Commons Attribution 3.0 Unported License).