The use of multiple ion chromatograms in on-line HPLC-MS for the characterization of post-translational and chemical modifications of proteins

In the post-genomic era, the characterization of the post- translational modifications and the three-dimensional structure of proteins will be of increasing interest. The post- translational modifications of proteins such as N-terminal processing, disulfide-bond formation, and glycosylation can be advantageously characterized by peptide mapping monitored with HPLC-MS. Cross-linking between a protein and a ligand can be used to identify contact points and thereby generate constraints for molecular modelin g of the ligand-protein interaction. Here we demonstrate the use of multiple ion chromatograms, which represent an extension of selected ion extraction, for the selective detection of low abundant components in peptide mixtures obtained by enzymatic digestion of proteins. The power of this technique will be demonstrated for the characterization of multiple N-terminal processing sites, the usage of putative glycosylation sites, the determination of low abundant disulfide-bond scrambled forms of proteins, and the characterization of photoadducts produced with photoreactive peptide analogs. (Int J Mass Spectrom 214 (2002) 37-5 1) (C) 2002 Elsevier Science B.V. All rights reserved