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Article: Copper-mediated peptide radical ions in the gas phase

TitleCopper-mediated peptide radical ions in the gas phase
Authors
Issue Date2004
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journal/jpcbfk
Citation
Journal Of Physical Chemistry B, 2004, v. 108 n. 30, p. 11170-11181 How to Cite?
AbstractMolecular radical cations, M ̇+, of amino acids and oligopeptides are produced by collision-induced dissociation of mixed complex ions, [Cu II(dien)M] ̇2+, that contain Cu II, an amine, typically diethylenetriamine (dien), and the oligopeptide, M. With dien as the amine ligand, abundant M ̇+ formation is observed only for the amino acids tryptophan and tyrosine, and oligopeptides that contain either the tryptophanyl or tyrosyl residue. Dissociation of the M ̇+ ion is rich and differs considerably from that of protonated amino acids and peptides. Facile fragmentation occurs around the α-carbon of the tryptophanyl residue. Cleavage of the N-C α bond and proton transfer from the exocyclic methylene group in the side chain to the N-terminal residue results in formation of the [z n -H] ̇+ ion and elimination of the N-terminal fragment as ammonia or an amide, depending on the position of the tryptophanyl residue. Cleavage of the C α - C bond of an oligopeptide containing a C-terminal tryptophan residue and proton transfer from the carboxylic group to the N-terminal fragment (a carbonyl oxygen atom) results in formation of the [a n + H] dot;+ ion and elimination of carbon dioxide. Both types of fragmentation have no analogous reactions in protonated peptides. For the M ̇+ of tryptophanylgly-cylglycine, WGG, elimination of the tryptophanyl side chain results in GGG ̇+. This radical cation fragments by eliminating its C-terminal glycine to give the [b 2 - H] ̇+ ion, which is an oxazolone and shares much of the structure and reactivity of the b 2 + ion from protonated triglycine. Density functional theory shows the mechanism of forming the [b 2 - H] ̇+ ion is similar to that of the b 2 + ion, although the free-energy barrier at 29.4 kcal/mol is lower. The [b 2 - H] ̇+ ion eliminates CO readily to give the [a 2 - H] ̇+ ion, which is an iminium radical ion.
Persistent Identifierhttp://hdl.handle.net/10722/168281
ISSN
2015 Impact Factor: 3.187
2015 SCImago Journal Rankings: 1.414
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorBagheriMajdi, Een_US
dc.contributor.authorKe, Yen_US
dc.contributor.authorOrlova, Gen_US
dc.contributor.authorChu, IKen_US
dc.contributor.authorHopkinson, ACen_US
dc.contributor.authorSiu, KWMen_US
dc.date.accessioned2012-10-08T03:17:00Z-
dc.date.available2012-10-08T03:17:00Z-
dc.date.issued2004en_US
dc.identifier.citationJournal Of Physical Chemistry B, 2004, v. 108 n. 30, p. 11170-11181en_US
dc.identifier.issn1520-6106en_US
dc.identifier.urihttp://hdl.handle.net/10722/168281-
dc.description.abstractMolecular radical cations, M ̇+, of amino acids and oligopeptides are produced by collision-induced dissociation of mixed complex ions, [Cu II(dien)M] ̇2+, that contain Cu II, an amine, typically diethylenetriamine (dien), and the oligopeptide, M. With dien as the amine ligand, abundant M ̇+ formation is observed only for the amino acids tryptophan and tyrosine, and oligopeptides that contain either the tryptophanyl or tyrosyl residue. Dissociation of the M ̇+ ion is rich and differs considerably from that of protonated amino acids and peptides. Facile fragmentation occurs around the α-carbon of the tryptophanyl residue. Cleavage of the N-C α bond and proton transfer from the exocyclic methylene group in the side chain to the N-terminal residue results in formation of the [z n -H] ̇+ ion and elimination of the N-terminal fragment as ammonia or an amide, depending on the position of the tryptophanyl residue. Cleavage of the C α - C bond of an oligopeptide containing a C-terminal tryptophan residue and proton transfer from the carboxylic group to the N-terminal fragment (a carbonyl oxygen atom) results in formation of the [a n + H] dot;+ ion and elimination of carbon dioxide. Both types of fragmentation have no analogous reactions in protonated peptides. For the M ̇+ of tryptophanylgly-cylglycine, WGG, elimination of the tryptophanyl side chain results in GGG ̇+. This radical cation fragments by eliminating its C-terminal glycine to give the [b 2 - H] ̇+ ion, which is an oxazolone and shares much of the structure and reactivity of the b 2 + ion from protonated triglycine. Density functional theory shows the mechanism of forming the [b 2 - H] ̇+ ion is similar to that of the b 2 + ion, although the free-energy barrier at 29.4 kcal/mol is lower. The [b 2 - H] ̇+ ion eliminates CO readily to give the [a 2 - H] ̇+ ion, which is an iminium radical ion.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journal/jpcbfken_US
dc.relation.ispartofJournal of Physical Chemistry Ben_US
dc.titleCopper-mediated peptide radical ions in the gas phaseen_US
dc.typeArticleen_US
dc.identifier.emailChu, IK:ivankchu@hku.hken_US
dc.identifier.authorityChu, IK=rp00683en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/jp049531qen_US
dc.identifier.scopuseid_2-s2.0-4043152965en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-4043152965&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume108en_US
dc.identifier.issue30en_US
dc.identifier.spage11170en_US
dc.identifier.epage11181en_US
dc.identifier.isiWOS:000222864200076-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridBagheriMajdi, E=6505978569en_US
dc.identifier.scopusauthoridKe, Y=7102816491en_US
dc.identifier.scopusauthoridOrlova, G=7007153895en_US
dc.identifier.scopusauthoridChu, IK=7103327484en_US
dc.identifier.scopusauthoridHopkinson, AC=15067169300en_US
dc.identifier.scopusauthoridSiu, KWM=35312218500en_US

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