Sargaeva, Nadezda P., Lin, Cheng and O’Connor, Peter B.. (2011) Differentiating N-terminal aspartic and isoaspartic acid residues in peptides. Analytical Chemistry, Vol.83 (No.17). pp. 6675-6682. ISSN 0003-2700

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Abstract

Formation of isoaspartic acid (isoAsp) is a common modification of aspartic acid (Asp) or asparagine (Asn) residue in proteins. Differentiation of isoAsp and Asp residues is a challenging task owing to their similar properties and identical molecular mass. It was recently shown that they can be differentiated using ion-electron or ion-ion interaction fragmentation methods (ExD) because these methods provide diagnostic fragments c + 57 and z(center dot) - 57 specific to the isoAsp residue. To date, however, the presence of such fragments has not been explored on peptides with an N-terminal isoAsp residue. To address this question, several N-terminal isoAsp-containing peptides were analyzed using ExD methods alone or combined with chromatography. A diagnostic fragment [M + 2H - 74](+center dot) was observed for the doubly charged precursor ions with N-terminal isoAsp residues. For some peptides, identification of the N-terminal isoAsp residue was challenging because of the low diagnostic ion peak intensity and the presence of interfering peaks. Supplemental activation was used to improve diagnostic ion detection. Further, N-terminal acetylation was offered as a means to overcome the interference problem by shifting the diagnostic fragment peak to [M + 2H - 116](+center dot).

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry Q Science > QP Physiology
Divisions:	Faculty of Science > Chemistry
Library of Congress Subject Headings (LCSH):	Tandem mass spectrometry, High performance liquid chromatography, Succinimides, Proteins -- Deamination, Peptides, Aspartic acid, Isoaspartic acid
Journal or Publication Title:	Analytical Chemistry
Publisher:	American Chemical Society
ISSN:	0003-2700
Date:	1 September 2011
Volume:	Vol.83
Number:	No.17
Number of Pages:	8
Page Range:	pp. 6675-6682
Identification Number:	10.1021/ac201223d
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), National Center for Research Resources (U.S.) (NCRR), National Institutes of Health (U.S.) (NIH), National Institute of General Medical Sciences (U.S.) (NIGMS)
Grant number:	EP/F034210/1 (EPSRC), P41 RR10888 (NIH/NCRR), R01GM078293 (NIH/NIGMS), S10 RR025082 (NIH/NCRR)
URI:	http://wrap.warwick.ac.uk/id/eprint/38421

Data sourced from Thomson Reuters' Web of Knowledge

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