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Article: Arginine-facilitated α- And π-radical migrations in glycylarginyltryptophan radical cations

TitleArginine-facilitated α- And π-radical migrations in glycylarginyltryptophan radical cations
Authors
Keywordsamino acids
cleavage reactions
gas-phase reactions
peptides
radical ions
Issue Date2011
PublisherWiley - V C H Verlag GmbH & Co. KGaA. The Journal's web site is located at http://www.wiley-vch.de/publish/en/journals/alphabeticIndex/2451
Citation
Chemistry - An Asian Journal, 2011, v. 6 n. 3, p. 888-898 How to Cite?
AbstractWe have used model tripeptides GXW (with X being one of the amino acid residues glycine (G), alanine (A), leucine (L), phenylalanine (F), glutamic acid (E), histidine (H), lysine (K), or arginine (R)) to study the effects of the basicity of the amino acid residue on the radical migrations and dissociations of odd-electron molecular peptide radical cations M .+ in the gas phase. Low-energy collision-induced dissociation (CID) experiments revealed that the interconvertibility of the isomers [G .XW] + (radical centered on the N-terminal α-carbon atom) and [GXW] .+ (radical centered on the π system of the indolyl ring) generally increased upon increasing the proton affinity of residue X. When X was arginine, the most basic amino acid, the two isomers were fully interconvertible and produced almost identical CID spectra despite the different locations of their initial radical sites. The presence of the very basic arginine residue allowed radical migrations to proceed readily among the [G .RW] + and [GRW] .+ isomers prior to their dissociations. Density functional theory calculations revealed that the energy barriers for isomerizations among the α-carbon-centered radical [G .RW] +, the π-centered radical [GRW] .+, and the β-carbon-centered radical [GRW β .] + (ca. 32-36 kcal mol -1) were comparable with those for their dissociations (ca. 32-34 kcal mol -1). The arginine residue in these GRW radical cations tightly sequesters the proton, thereby resulting in minimal changes in the chemical environment during the radical migrations, in contrast to the situation for the analogous GGW system, in which the proton is inefficiently stabilized during the course of radical migration. Basic instinct: Model tripeptides GXW (X=amino acid residues glycine (G), alanine (A), leucine (L), phenylalanine (F), glutamic acid (E), histidine (H), lysine (K), or arginine (R)) have been used to study the effects of the basicity of the amino acid residue on the radical migrations and dissociations of odd-electron molecular peptide radical cations M .+ in the gas phase (see picture). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Persistent Identifierhttp://hdl.handle.net/10722/135024
ISSN
2015 Impact Factor: 4.592
2015 SCImago Journal Rankings: 1.833
ISI Accession Number ID
Funding AgencyGrant Number
Hong Kong Research Grants Council (RGC), Hong Kong Special Administrative Region, ChinaHKU7012/08P
HKU7016/10P
Hong Kong RGC
City University of University of Hong KongSRG 7002552
Funding Information:

This study was supported by the Hong Kong Research Grants Council (RGC), Hong Kong Special Administrative Region, China (project nos. HKU7012/08P and HKU7016/10P). T.S. and D.C.M.N. thank the Hong Kong RGC for supporting their studentships. C.K.S. thanks the City University of Hong Kong for their financial support (CityU SRG 7002552).

References

 

DC FieldValueLanguage
dc.contributor.authorSong, Ten_HK
dc.contributor.authorNg, DCMen_HK
dc.contributor.authorQuan, Qen_HK
dc.contributor.authorSiu, CKen_HK
dc.contributor.authorChu, IKen_HK
dc.date.accessioned2011-07-27T01:26:13Z-
dc.date.available2011-07-27T01:26:13Z-
dc.date.issued2011en_HK
dc.identifier.citationChemistry - An Asian Journal, 2011, v. 6 n. 3, p. 888-898en_HK
dc.identifier.issn1861-4728en_HK
dc.identifier.urihttp://hdl.handle.net/10722/135024-
dc.description.abstractWe have used model tripeptides GXW (with X being one of the amino acid residues glycine (G), alanine (A), leucine (L), phenylalanine (F), glutamic acid (E), histidine (H), lysine (K), or arginine (R)) to study the effects of the basicity of the amino acid residue on the radical migrations and dissociations of odd-electron molecular peptide radical cations M .+ in the gas phase. Low-energy collision-induced dissociation (CID) experiments revealed that the interconvertibility of the isomers [G .XW] + (radical centered on the N-terminal α-carbon atom) and [GXW] .+ (radical centered on the π system of the indolyl ring) generally increased upon increasing the proton affinity of residue X. When X was arginine, the most basic amino acid, the two isomers were fully interconvertible and produced almost identical CID spectra despite the different locations of their initial radical sites. The presence of the very basic arginine residue allowed radical migrations to proceed readily among the [G .RW] + and [GRW] .+ isomers prior to their dissociations. Density functional theory calculations revealed that the energy barriers for isomerizations among the α-carbon-centered radical [G .RW] +, the π-centered radical [GRW] .+, and the β-carbon-centered radical [GRW β .] + (ca. 32-36 kcal mol -1) were comparable with those for their dissociations (ca. 32-34 kcal mol -1). The arginine residue in these GRW radical cations tightly sequesters the proton, thereby resulting in minimal changes in the chemical environment during the radical migrations, in contrast to the situation for the analogous GGW system, in which the proton is inefficiently stabilized during the course of radical migration. Basic instinct: Model tripeptides GXW (X=amino acid residues glycine (G), alanine (A), leucine (L), phenylalanine (F), glutamic acid (E), histidine (H), lysine (K), or arginine (R)) have been used to study the effects of the basicity of the amino acid residue on the radical migrations and dissociations of odd-electron molecular peptide radical cations M .+ in the gas phase (see picture). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.en_HK
dc.languageengen_US
dc.publisherWiley - V C H Verlag GmbH & Co. KGaA. The Journal's web site is located at http://www.wiley-vch.de/publish/en/journals/alphabeticIndex/2451en_HK
dc.relation.ispartofChemistry - An Asian Journalen_HK
dc.subjectamino acidsen_HK
dc.subjectcleavage reactionsen_HK
dc.subjectgas-phase reactionsen_HK
dc.subjectpeptidesen_HK
dc.subjectradical ionsen_HK
dc.subject.meshAmino Acids - chemistry-
dc.subject.meshArginine - chemistry-
dc.subject.meshCations - chemistry-
dc.subject.meshFree Radicals - chemistry-
dc.subject.meshTryptophan - analogs and derivatives-
dc.titleArginine-facilitated α- And π-radical migrations in glycylarginyltryptophan radical cationsen_HK
dc.typeArticleen_HK
dc.identifier.emailChu, IK:ivankchu@hku.hken_HK
dc.identifier.authorityChu, IK=rp00683en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1002/asia.201000677en_HK
dc.identifier.pmid21271680-
dc.identifier.scopuseid_2-s2.0-79951974137en_HK
dc.identifier.hkuros186171en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-79951974137&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume6en_HK
dc.identifier.issue3en_HK
dc.identifier.spage888en_HK
dc.identifier.epage898en_HK
dc.identifier.isiWOS:000288095500022-
dc.publisher.placeGermanyen_HK
dc.identifier.scopusauthoridSong, T=36087959100en_HK
dc.identifier.scopusauthoridNg, DCM=36981534500en_HK
dc.identifier.scopusauthoridQuan, Q=37018675200en_HK
dc.identifier.scopusauthoridSiu, CK=7006550712en_HK
dc.identifier.scopusauthoridChu, IK=7103327484en_HK

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