Partial methanolysis and fast atom bombardment mass spectrometry of peptides containing sulphurated ammo acids

✍ Scribed by Salvatore Foti; Rosaria Saletti; Donata Marietta

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 377 KB
• Volume: 26
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210261018

✦ Synopsis

Sequence determination by partial methanolysis and fast atom bombardment (FAB) mass spectrometry of peptides containing cysteine and methionine was investigated. Cysteine-containing peptides require methylation of the sulphydryl group by methyl iodide to give a stable S-methylcysteinyl residue prior to partial methanolysis and mass spectrometry. Methionine-containing peptides undergo partially a methylation on sulphur during methanolysis, with formation of an S-methylsulphonium ion which under FAB conditions is extracted from the matrix and eliminates methyl sulphide in the gas phase. The presence of additional peaks due to chemical modifications or gas-phase fragmentations, however, does not interfere with the sequence information of the spectra.