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Article: Proton migration and tautomerism in protonated triglycine

TitleProton migration and tautomerism in protonated triglycine
Authors
Issue Date2001
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.html
Citation
Journal Of The American Chemical Society, 2001, v. 123 n. 13, p. 3006-3012 How to Cite?
AbstractProton migration in protonated glycylglycylglycine (GGG) has been investigated by using density functional theory at the B3LYP/6-31++G(d,p) level of theory. On the protonated GGG energy hypersurface 19 critical points have been characterized, 11 as minima and 8 as first-order saddle points. Transition state structures for interconversion between eight of these minima are reported, starting from a structure in which there is protonation at the amino nitrogen of the N-terminal glycyl residue following the migration of the proton until there is fragmentation into protonated 2-aminomethyl-5-oxazolone (the b 2 ion) and glycine. Individual free energy barriers are small, ranging from 4.3 to 18.1 kcal mol -1. The most favorable site of protonation on GGG is the carbonyl oxygen of the N-terminal residue. This isomer is stabilized by a hydrogen bond of the type O-H···N with the N-terminal nitrogen atom, resulting in a compact five-membered ring. Another oxygen-protonated isomer with hydrogen bonding of the type O-H···O, resulting in a seven-membered ring, is only 0.1 kcal mol -1 higher in free energy. Protonation on the N-terminal nitrogen atom produces an isomer that is about 1 kcal mol -1 higher in free energy than isomers resulting from protonation on the carbonyl oxygen of the N-terminal residue. The calculated energy barrier to generate the b 2 ion from protonated GGG is 32.5 kcal mol -1 via TS(6→7). The calculated basicity and proton affinity of GGG from our results are 216.3 and 223.8 kcal mol -1, respectively, These values are 3-4 kcal mol -1 lower than those from previous calculations and are in excellent agreement with recently revised experimental values.
Persistent Identifierhttp://hdl.handle.net/10722/167679
ISSN
2015 Impact Factor: 13.038
2015 SCImago Journal Rankings: 7.123
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorRodriquez, CFen_US
dc.contributor.authorCunje, Aen_US
dc.contributor.authorShoeib, Ten_US
dc.contributor.authorChu, IKen_US
dc.contributor.authorHopkinson, ACen_US
dc.contributor.authorSiu, KWMen_US
dc.date.accessioned2012-10-08T03:09:54Z-
dc.date.available2012-10-08T03:09:54Z-
dc.date.issued2001en_US
dc.identifier.citationJournal Of The American Chemical Society, 2001, v. 123 n. 13, p. 3006-3012en_US
dc.identifier.issn0002-7863en_US
dc.identifier.urihttp://hdl.handle.net/10722/167679-
dc.description.abstractProton migration in protonated glycylglycylglycine (GGG) has been investigated by using density functional theory at the B3LYP/6-31++G(d,p) level of theory. On the protonated GGG energy hypersurface 19 critical points have been characterized, 11 as minima and 8 as first-order saddle points. Transition state structures for interconversion between eight of these minima are reported, starting from a structure in which there is protonation at the amino nitrogen of the N-terminal glycyl residue following the migration of the proton until there is fragmentation into protonated 2-aminomethyl-5-oxazolone (the b 2 ion) and glycine. Individual free energy barriers are small, ranging from 4.3 to 18.1 kcal mol -1. The most favorable site of protonation on GGG is the carbonyl oxygen of the N-terminal residue. This isomer is stabilized by a hydrogen bond of the type O-H···N with the N-terminal nitrogen atom, resulting in a compact five-membered ring. Another oxygen-protonated isomer with hydrogen bonding of the type O-H···O, resulting in a seven-membered ring, is only 0.1 kcal mol -1 higher in free energy. Protonation on the N-terminal nitrogen atom produces an isomer that is about 1 kcal mol -1 higher in free energy than isomers resulting from protonation on the carbonyl oxygen of the N-terminal residue. The calculated energy barrier to generate the b 2 ion from protonated GGG is 32.5 kcal mol -1 via TS(6→7). The calculated basicity and proton affinity of GGG from our results are 216.3 and 223.8 kcal mol -1, respectively, These values are 3-4 kcal mol -1 lower than those from previous calculations and are in excellent agreement with recently revised experimental values.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/journals/jacsat/index.htmlen_US
dc.relation.ispartofJournal of the American Chemical Societyen_US
dc.subject.meshEnergy Transferen_US
dc.subject.meshIsomerismen_US
dc.subject.meshOligopeptides - Chemistry - Metabolismen_US
dc.subject.meshProtein Bindingen_US
dc.subject.meshProtonsen_US
dc.subject.meshQuantum Theoryen_US
dc.titleProton migration and tautomerism in protonated triglycineen_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/ja0015904en_US
dc.identifier.pmid11457011-
dc.identifier.scopuseid_2-s2.0-0034829543en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0034829543&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume123en_US
dc.identifier.issue13en_US
dc.identifier.spage3006en_US
dc.identifier.epage3012en_US
dc.identifier.isiWOS:000167806300009-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridRodriquez, CF=7004085075en_US
dc.identifier.scopusauthoridCunje, A=6602535833en_US
dc.identifier.scopusauthoridShoeib, T=6603516521en_US
dc.identifier.scopusauthoridChu, IK=7103327484en_US
dc.identifier.scopusauthoridHopkinson, AC=15067169300en_US
dc.identifier.scopusauthoridSiu, KWM=35312218500en_US

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