Elucidating the various multi-phosphorylation statuses of protein functional regions by 193-nm ultraviolet photodissociation

Ultraviolet photodissociation is a high-energy fast excitation method in mass spectrometry and has been successfully applied for the elucidation of sequences and structures of biomolecules. However, its ability to distinguish the phosphorylation sites isomers of multi-phosphopeptides has been not systematically investigated until now. A 193-nm ultraviolet laser dissociation mass spectrometry system was established in this study and applied to elucidate the complex multi-phosphorylation statuses mimicking the functional regions of Sic1, Gli3 and Tau. The numbers of matched fragment ions and phosphorylation site-determining ions were improved on average 123% and 104%, respectively, by utilizing the ultraviolet photodissociation strategy, comparing to the typically utilized collision induced dissociation strategy. Finally, 94% phosphorylation sites within various statuses were unambiguously elucidated. (C) 2018 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.