Strategy for the identification of sites of phosphorylation in proteins: neutral loss triggered electron capture dissociation.

Sweet, Steve, Creese, A.J and Cooper, H.J (2006) Strategy for the identification of sites of phosphorylation in proteins: neutral loss triggered electron capture dissociation. Analytical Chemistry, 78 (21). pp. 7563-7569. ISSN 00032700

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Abstract

We have previously demonstrated the suitability of data-dependent electron capture dissociation (ECD) for incorporation into proteomic strategies. The ability to directly determine sites of phosphorylation is a major advantage of electron capture dissociation; however, the low stoichiometry associated with phosphorylation means that phosphopeptides are often overlooked in data-dependent ECD analyses. In contrast, collision-induced dissociation (CID) tends to result in loss of the labile phosphate group, often at the expense of sequence fragments. Here, we demonstrate a novel strategy for the characterization of phosphoproteins which exploits the neutral loss feature of CID such that focused ECD of phosphopeptides is achieved. Peptides eluting from a liquid chromatograph are first subjected to CID, and if a neutral loss of 98 Da (corresponding to H3PO4) from the precursor is observed, ECD of that same precursor is performed; i.e., the method comprises neutral loss triggered ECD (NL-ECD-MS/MS). The method was applied to tryptic digests of β-casein and α-casein. For α-casein, four sites of phosphorylation were identified with NL-ECD-MS/MS compared with a single site identified by ECD-MS/MS. The method also resulted in ECD of a doubly phosphorylated peptide. A further benefit of the method is that overall protein sequence coverage is unproved. Sequence information from non-phosphorylated peptides is obtained as a result of the CID step

Item Type: Article
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
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Depositing User: Steve Sweet
Date Deposited: 06 Feb 2012 19:10
Last Modified: 23 Jul 2012 11:33
URI: http://srodev.sussex.ac.uk/id/eprint/19463
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