Decomposition of protein nitrosothiolsin matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry

• Published in: Journal of mass spectrometry. Vol. 38; no. 5; pp. 526 - 530
• Main Authors: Kaneko, Rina, Wada, Yoshinao
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.05.2003
• Subjects: collision-induced dissociation; electrospray ionization; Humans; matrix-assisted laser desorption/ionization; nitric oxide; Nitrogen Compounds - chemistry; nitrosothiol; nitrosylation; Prealbumin - chemistry; Proteins - chemistry; Serum Albumin - chemical synthesis; Serum Albumin - chemistry; Spectrometry, Mass, Electrospray Ionization; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Sulfhydryl Compounds - chemistry; transthyretin
• ISSN: 1076-5174; 1096-9888
• 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. Copyright © 2003 John Wiley & Sons, Ltd.