Amino Acid Sequence Determination of Cyclic Peptides by Tandem Mass Spectrometry Coupled with Fast Atom Bombardment Ionization

The unambiguous amino acid sequence analysis of a cyclic decapeptide antibiotic, gramicidin S, was performed using the title method and a B2/E constant linked scanning technique. The methodolgy for the sequence analysis involves the structure determination by tandem mass spectrometry (MS/MS) of a small acylium ion containing two or three amino acid residues, and the stepwise extension of the analyzed sequence by use of a combination of MS/MS and linked scanning.