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Abstract No.: ThP-173
Session: Peptide Sequencing
Presentation date: Thu, Aug 31, 2006
Presentation time: 09:50 – 11:20

Identification of Disulfide Links in Peptides and Proteins Using Negative Ion Electrospray Mass Spectrometry

Hayley Jo Andreazza1, Daniel Bilusich1, John H. Bowie1

1 University of Adelaide, Adelaide, Australia

Correspondence address: Hayley Jo Andreazza, University of Adelaide, Chemistry, North Terrace, Adelaide, SA, 5005 Australia.

Keywords: Disulfide; Electrospray Ionization (ESI); Negative Ion; Protein Sequencing.

Novel aspect: The direct determination of disulphide linkages using negative ion mass spectrometry.


Intramolecular disulfide links may be identified by pronounced loss of H2S2 from the (M-H)- parent. Subsequent fragmentation of the [(M-H)- - H2S2] fragment anion provides sequencing information. Peptides containing two disulfide units show the [(M-H)- - H2S2 -H2S2] fragmentation. Insulin contains two intramolecular disulfides and one intermolecular disulphide unit. MS/MS data from the (M-H)- parent, and MS/MS/MS of a fragment anion identify the presence of the three disulfide units. We are currently investigating the applicability of the negative ion method for tryptic digests of proteins.

1. D. Bilusich et al., Rapid Commun. Mass Spectrom. 19, 3063 (2005).