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Article: Formation, isomerization, and dissociation of a-carbon-centered and π-centered glycylglycyltryptophan radical cations

TitleFormation, isomerization, and dissociation of a-carbon-centered and π-centered glycylglycyltryptophan radical cations
Authors
Issue Date2010
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journal/jpcbfk
Citation
Journal Of Physical Chemistry B, 2010, v. 114 n. 6, p. 2270-2280 How to Cite?
AbstractGas phase fragmentations of two isomeric radical cationic tripeptides of glycylglycyltryptophan-[G •GW] + and [GGW] •+-with well-defined initial radical sites at the a-carbon atom and the 3-methylindóle ring, respectively, have been studied using collision-induced dissociation (CID), density functional theory (DFT), and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Substantially different low-energy CID spectra were obtained for these two isomeric GGW structures, suggesting that they did not interconvert on the time scale of these experiments. DFT and RRKM calculations were used to investigate the influence of the kinetics, stabilities, and locations of the radicals on the competition between the isomerization and dissociation channels. The calculated isomerization barrier between the GGW radical cations (> 35.4 kcal/mol) was slightly higher than the barrier for competitive dissociation of these species (<30.5 kcal/mol); the corresponding microcanonical rate constants for isomerization obtained from RRKM calculations were all considerably lower than the dissociation rates at all internal energies. Thus, interconversion between the GGW isomers examined in this study cannot compete with their fragmentations. © 2010 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/130959
ISSN
2015 Impact Factor: 3.187
2015 SCImago Journal Rankings: 1.414
ISI Accession Number ID
Funding AgencyGrant Number
University of Hong Kong (UGC)
Hong Kong Research Grants Council, Special Administrative Region, ChinaHKU 7018/06P
HKU 7012/08P
U. S. Department of Energy
City University of Hong Kong
Funding Information:

Most of the research described in this manuscript was supported by the University of Hong Kong (UGC) and the Hong Kong Research Grants Council, Special Administrative Region, China (Project No. HKU 7018/06P and Project No. HKU 7012/08P). D.C.M.N. and T.S. thank the Hong Kong RGC for supporting their studentship. J.L. acknowledges support from the Chemical Sciences Division, Office of Basic Energy Sciences of the U. S. Department of Energy. Part of the work presented here was performed at the W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the U.S. Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. Department of Energy. C.K.S. is grateful for financial support from the City University of Hong Kong.

References
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DC FieldValueLanguage
dc.contributor.authorNg, DCMen_HK
dc.contributor.authorSong, Ten_HK
dc.contributor.authorSiu, SOen_HK
dc.contributor.authorSiu, CKen_HK
dc.contributor.authorLaskin, Jen_HK
dc.contributor.authorChu, IKen_HK
dc.date.accessioned2011-01-18T01:53:25Z-
dc.date.available2011-01-18T01:53:25Z-
dc.date.issued2010en_HK
dc.identifier.citationJournal Of Physical Chemistry B, 2010, v. 114 n. 6, p. 2270-2280en_HK
dc.identifier.issn1520-6106en_HK
dc.identifier.urihttp://hdl.handle.net/10722/130959-
dc.description.abstractGas phase fragmentations of two isomeric radical cationic tripeptides of glycylglycyltryptophan-[G •GW] + and [GGW] •+-with well-defined initial radical sites at the a-carbon atom and the 3-methylindóle ring, respectively, have been studied using collision-induced dissociation (CID), density functional theory (DFT), and Rice-Ramsperger-Kassel-Marcus (RRKM) theory. Substantially different low-energy CID spectra were obtained for these two isomeric GGW structures, suggesting that they did not interconvert on the time scale of these experiments. DFT and RRKM calculations were used to investigate the influence of the kinetics, stabilities, and locations of the radicals on the competition between the isomerization and dissociation channels. The calculated isomerization barrier between the GGW radical cations (> 35.4 kcal/mol) was slightly higher than the barrier for competitive dissociation of these species (<30.5 kcal/mol); the corresponding microcanonical rate constants for isomerization obtained from RRKM calculations were all considerably lower than the dissociation rates at all internal energies. Thus, interconversion between the GGW isomers examined in this study cannot compete with their fragmentations. © 2010 American Chemical Society.en_HK
dc.languageeng-
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journal/jpcbfken_HK
dc.relation.ispartofJournal of Physical Chemistry Ben_HK
dc.subject.meshAmino Acid Sequence-
dc.subject.meshCarbon - chemistry-
dc.subject.meshCations - chemistry-
dc.subject.meshIsomerism-
dc.subject.meshOligopeptides - chemistry-
dc.titleFormation, isomerization, and dissociation of a-carbon-centered and π-centered glycylglycyltryptophan radical cationsen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1520-6106&volume=114&issue=6&spage=2270&epage=2280&date=2010&atitle=Formation,+Isomerization,+and+Dissociation+of+alpha-Carbon-Centered+and+pi-Centered+Glycylglycyltryptophan+Radical+Cations-
dc.identifier.emailChu, IK:ivankchu@hku.hken_HK
dc.identifier.authorityChu, IK=rp00683en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1021/jp908599aen_HK
dc.identifier.pmid20099850-
dc.identifier.scopuseid_2-s2.0-77649150696en_HK
dc.identifier.hkuros171567-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-77649150696&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume114en_HK
dc.identifier.issue6en_HK
dc.identifier.spage2270en_HK
dc.identifier.epage2280en_HK
dc.identifier.isiWOS:000274355400023-
dc.publisher.placeUnited Statesen_HK
dc.relation.projectFacile generation and characterization of cationic and anionic radical peptides: ligand effects and peptide structures-
dc.identifier.scopusauthoridNg, DCM=36981534500en_HK
dc.identifier.scopusauthoridSong, T=36087959100en_HK
dc.identifier.scopusauthoridSiu, SO=8603087200en_HK
dc.identifier.scopusauthoridSiu, CK=7006550712en_HK
dc.identifier.scopusauthoridLaskin, J=7102409836en_HK
dc.identifier.scopusauthoridChu, IK=7103327484en_HK

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