Decoding the Fucose Migration Product during Mass-Spectrometric Analysis of Blood Group Epitopes
Lettow, M.; Mucha, E.; Greis, K.; Yaman, M.; Manz, C.; Hoffmann, W.; Lambeth, T.R.; Meijer, G.; Julian, R.R.; von Helden, G.; Marianski, M.;* Pagel, K.;* – 2023
Fucose is a signaling carbohydrate that is attached at the end of glycan processing. It is involved in a range of processes, such as the selectin-dependent leukocyte adhesion or pathogen-receptor interactions. Mass-spectrometric techniques, which are commonly used to determine the structure of glycans, frequently show fucose-containing chimeric fragments that obfuscate the analysis. The rearrangement leading to these fragments – often referred to as fucose migration – has been known for more than 25 years, but the chemical identity of the rearrangement product remains unclear. In this work, we combine ion-mobility spectrometry, radical-directed dissociation mass spectrometry, cryogenic-ion IR spectroscopy, and density-functional theory calculations to deduce the product of the rearrangement in the model trisaccharides Lewis x and blood group H2. The structural search yields the fucose moiety attached to the galactose with an α(1 → 6) glycosidic bond as the most likely product.