title: Characterization of O-acetylation in sialoglycans by MALDI-MS using a combination of methylamidation and permethylation.
abstract: O-Acetylation of sialic acid in protein N-glycans is an important modification and can occur at either 4-, 7-, 8- or 9-position in various combinations. This modification is usually labile under alkaline reaction conditions. Consequently, a permethylation-based analytical method, which has been widely used in glycomics studies, is not suitable for profiling O-acetylation of sialic acids due to the harsh reaction conditions. Alternatively, methylamidation can be used for N-glycan analysis without affecting the base-labile modification of sialic acid. In this report, we applied both permethylation and methylamidation approaches to the analysis of O-acetylation in sialic acids. It has been demonstrated that methylamidation not only stabilizes sialic acids during MALDI processing but also allow for characterization of their O-acetylation pattern. In addition, LC-MS/MS experiments were carried out to distinguish between the O-acetylated glycans with potential isomeric structures. The repeatability of methylamidation was examined to evaluate the applicability of the approach to profiling of O-acetylation in sialic acids. In conclusion, the combination of methylamidation and permethylation methodology is a powerful MALDI-TOF MS-based tool for profiling O-acetylation in sialic acids applicable to screening of N-glycans.
authors.affiliation: Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Institute for Interdisciplinary Research, School of Chemical and Environmental Engineering, Jianghan University, Wuhan, 430056 China.
authors.forename: Zhaoguan
authors.initials: Z
authors.lastname: Wu
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China.
authors.forename: Henghui
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Institute for Interdisciplinary Research, School of Chemical and Environmental Engineering, Jianghan University, Wuhan, 430056 China.
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074 China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Institute for Interdisciplinary Research, School of Chemical and Environmental Engineering, Jianghan University, Wuhan, 430056 China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zheng
authors.affiliation: Human Health Therapeutics, National Research Council Canada, 100 Sussex Drive, Ottawa, ON, K1A 0R6 Canada.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li