Kaneko Rina, Wada Yoshinao
Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka 594-1101, Japan.
J Mass Spectrom. 2003 May;38(5):526-30. doi: 10.1002/jms.466.
The S-nitrosylation of proteins is involved in the trafficking of nitric oxide (NO) in intra- and extracellular milieus. To establish a mass spectrometric method for identifying this post-translational modification of proteins, a synthetic peptide and transthyretin were S-nitrosylated in vitro and analyzed by electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The intact molecular ion species of nitrosylated compounds was identified in the ESI mass spectrum without elimination of the NO group. However, the labile nature of the S-NO bond was evident when the in-source fragmentation efficiently generated M + H - 30 ions. The decomposition was prominent for multiply charged transthyretin ions with high charge states under ordinary ESI conditions, indicating that the application of minimum nozzle potentials was essential for delineating the stoichiometry of nitrosylation in proteins. With MALDI, the S-NO bond cleavage occurred during the ionization process, and the subsequent reduction generated M + H - 29 ions.
蛋白质的S-亚硝基化参与一氧化氮（NO）在细胞内和细胞外环境中的运输。为建立一种用于鉴定蛋白质这种翻译后修饰的质谱方法，在体外对一种合成肽和转甲状腺素蛋白进行了S-亚硝基化，并通过电喷雾电离（ESI）和基质辅助激光解吸/电离（MALDI）质谱进行分析。在ESI质谱中鉴定出了亚硝基化化合物的完整分子离子物种，且未消除NO基团。然而，当源内裂解有效地产生M + H - 30离子时，S-NO键的不稳定性质就很明显了。在普通ESI条件下，对于高电荷态的多电荷转甲状腺素蛋白离子，这种分解很突出，这表明应用最小的喷嘴电位对于确定蛋白质中亚硝基化的化学计量至关重要。使用MALDI时，S-NO键在电离过程中发生裂解，随后的还原产生M + H - 29离子。
