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Updated: Jun 8, 2026
Protease- and Acid-catalyzed Labeling Workflows Employing 18O-enriched Water
Published on: February 20, 2013
Microwave-assisted 18O-labeling of proteins catalyzed by formic acid
Ning Liu1, Hanzhi Wu, Hongxia Liu
1Central Laboratory, The Second Hospital of Jilin University, Changchun, China, Department of Chemistry, Hong Kong Baptist University, Hong Kong SAR, China, The Key Laboratory of Chemical Biology, Guangdong Province, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China, Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fuzhou University, Fuzhou 350002, Fujian, China.
Abstract:
Oxygen exchange may occur at carboxyl groups catalyzed by acid. The reaction, however, takes at least several days at room temperature. The long-time exchanging reaction often prevents its application from protein analysis. In this study, an (18)O-labeling method utilizing microwave-assisted acid hydrolysis was developed. After being dissolved in (16)O/(18)O (1:1) water containing 2.5% formic acid, protein samples were exposed to microwave irradiation. LC-MS/MS analysis of the resulted peptide mixtures indicated that oxygen in the carboxyl groups from glutamic acid, aspartic acid, and the C-terminal residues could be efficiently exchanged with (18)O within less than 15 min. The rate of back exchange was so slow that no detectable back exchange could be found during the HPLC run.
