Linked Life Data

19412918

Source:http://linkedlifedata.com/resource/pubmed/id/19412918

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
2009-5-18
pubmed:abstractText
The characteristic fragmentations of a pTyr group in the negative ion electrospray mass spectrum of the [M-H](-) anion of a peptide or protein involve the formation of PO(3) (-) (m/z 79) and the corresponding [(M-H)(-)-HPO(3)](-) species. In some tetrapeptides where pTyr is the third residue, these characteristic anion fragmentations are accompanied by ions corresponding to H(2)PO(4) (-) and [(M-H)(-)-H(3)PO(4)](-) (these are fragmentations normally indicating the presence of pSer or pThr). These product ions are formed by rearrangement processes which involve initial nucleophilic attack of a C-terminal -CO(2) (-) [or -C(==NH)O(-)] group at the phosphorus of the Tyr side chain [an S(N)2(P) reaction]. The rearrangement reactions have been studied by ab initio calculations at the HF/6-31+G(d)//AM1 level of theory. The study suggests the possibility of two processes following the initial S(N)2(P) reaction. In the rearrangement (involving a C-terminal carboxylate anion) with the lower energy reaction profile, the formation of the H(2)PO(4) (-) and [(M-H)(-)-H(3)PO(4)](-) anions is endothermic by 180 and 318 kJ mol(-1), respectively, with a maximum barrier (to a transition state) of 229 kJ mol(-1). The energy required to form H(2)PO(4) (-) by this rearrangement process is (i) more than that necessary to effect the characteristic formation of PO(3) (-) from pTyr, but (ii) comparable with that required to effect the characteristic alpha, beta and gamma backbone cleavages of peptide negative ions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1097-0231
pubmed:author
pubmed:copyrightInfo
Copyright (c) 2009 John Wiley & Sons, Ltd.
pubmed:issnType
Electronic
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1669-77
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Negative ion fragmentations of deprotonated peptides containing post-translational modifications. An unusual cyclisation/rearrangement involving phosphotyrosine; a joint experimental and theoretical study.
pubmed:affiliation
Department of Chemistry, The University of Adelaide, South Australia, 5005, Australia.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't