Microwave-Assisted 18O-Labeling of Proteins Catalyzed by Formic Acid

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• 作者：Ning Liu ; Hanzhi Wu ; Hongxia Liu ; Guonan Chen ; Zongwei Cai
• 刊名：Analytical Chemistry
• 出版年：2010
• 出版时间：November 1, 2010
• 年：2010
• 卷：82
• 期：21
• 页码：9122-9126
• 全文大小：191K
• 年卷期：v.82,no.21(November 1, 2010)
• ISSN：1520-6882

文摘

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 ¹⁸O-labeling method utilizing microwave-assisted acid hydrolysis was developed. After being dissolved in ¹⁶O/¹⁸O (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 ¹⁸O 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.