Fast atom bombardment (FAB) mass spectra of protein digests: Hen and duck egg-white lysozymes

Abstract

Direct measurement of protein digests by fast atom bombardment mass spectrometry was examined in detail under various conditions such as with different amounts of sample and kinds of matrix. The results indicated that (i) signals of peptides covering, over 90% of the protein sequence could be detected in the mass spectrum; (ii) almost all signals of peptides including those of over 3000 u could be recorded with about 5 μg of protein digest; (iii) a peptide containing a cystine residue(s) gave the signal of the mother peptide together with that of its fragments formed by cleavage of the disulfide linkage.