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Article: Proton NMR study of structural perturbation in sperm whale myoglobin due to pentaammineruthenium(III) groups appended to surface histidyl imidazoles

TitleProton NMR study of structural perturbation in sperm whale myoglobin due to pentaammineruthenium(III) groups appended to surface histidyl imidazoles
Authors
Issue Date1984
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, 1984, v. 106 n. 21, p. 6213-6217 How to Cite?
AbstractRuthenium-labeled sperm whale myoglobin, [a5Ru]3Mb (a = NH3), which exhibits novel catalytic properties, and its model compound [a5RuImH]Cl3·2H2O (ImH = imidazole) have been investigated by 360-MHz 1H NMR. The model compound in 2H2O exhibits three nonlabile single-proton peaks corresponding to 2′-H, 5′-H, and 4′-H of the coordinated imidazole at -31.2, -2.5, and near 4.7 ppm at 25°C and pH 6.1, respectively. A pH titration gives a single pK 8.4 for deprotonation of the imidazole, with resulting increases of imidazole contact shifts. Ruthenium-labeled Mb and Ru-labeled apo-Mb also exhibit peaks at -36 ppm, which are assigned to the 2′-H of the imidazoles of His-12, His-81, and His-113, Integration of these 2′-H peaks relative to a heme methyl allows determination of the extent of reaction of surface histidines with pentaammineruthenium(III). Detailed comparison of the hyperfine shifted resonances for metaquo, methydroxy, metcyano, metazide, and deoxy forms of the proteins show negligible influence of the Ru chromophores on shifts, indicating protein folding essentially unaltered from that in the native protein. The difference in the high-spin/low-spin separation in the metazide form for the native and Ru-labeled proteins is estimated at only 24 cal, indicating a slightly weaker axial ligand field for the latter derivative. The decreased proton spin-lattice relaxation times and increased line widths of Ru-labeled Mb relative to native Mb complexes indicate the presence of metal-metal interactions which influence the electron-spin relaxation of the iron center. © 1984 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/167795
ISSN
2015 Impact Factor: 13.038
2015 SCImago Journal Rankings: 7.123
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorToi, Hen_US
dc.contributor.authorLa Mar, GNen_US
dc.contributor.authorMargalit, Ren_US
dc.contributor.authorChe, CMen_US
dc.contributor.authorGray, HBen_US
dc.date.accessioned2012-10-08T03:11:43Z-
dc.date.available2012-10-08T03:11:43Z-
dc.date.issued1984en_US
dc.identifier.citationJournal Of The American Chemical Society, 1984, v. 106 n. 21, p. 6213-6217en_US
dc.identifier.issn0002-7863en_US
dc.identifier.urihttp://hdl.handle.net/10722/167795-
dc.description.abstractRuthenium-labeled sperm whale myoglobin, [a5Ru]3Mb (a = NH3), which exhibits novel catalytic properties, and its model compound [a5RuImH]Cl3·2H2O (ImH = imidazole) have been investigated by 360-MHz 1H NMR. The model compound in 2H2O exhibits three nonlabile single-proton peaks corresponding to 2′-H, 5′-H, and 4′-H of the coordinated imidazole at -31.2, -2.5, and near 4.7 ppm at 25°C and pH 6.1, respectively. A pH titration gives a single pK 8.4 for deprotonation of the imidazole, with resulting increases of imidazole contact shifts. Ruthenium-labeled Mb and Ru-labeled apo-Mb also exhibit peaks at -36 ppm, which are assigned to the 2′-H of the imidazoles of His-12, His-81, and His-113, Integration of these 2′-H peaks relative to a heme methyl allows determination of the extent of reaction of surface histidines with pentaammineruthenium(III). Detailed comparison of the hyperfine shifted resonances for metaquo, methydroxy, metcyano, metazide, and deoxy forms of the proteins show negligible influence of the Ru chromophores on shifts, indicating protein folding essentially unaltered from that in the native protein. The difference in the high-spin/low-spin separation in the metazide form for the native and Ru-labeled proteins is estimated at only 24 cal, indicating a slightly weaker axial ligand field for the latter derivative. The decreased proton spin-lattice relaxation times and increased line widths of Ru-labeled Mb relative to native Mb complexes indicate the presence of metal-metal interactions which influence the electron-spin relaxation of the iron center. © 1984 American Chemical Society.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.titleProton NMR study of structural perturbation in sperm whale myoglobin due to pentaammineruthenium(III) groups appended to surface histidyl imidazolesen_US
dc.typeArticleen_US
dc.identifier.emailChe, CM:cmche@hku.hken_US
dc.identifier.authorityChe, CM=rp00670en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/ja00333a016-
dc.identifier.scopuseid_2-s2.0-0037876655en_US
dc.identifier.volume106en_US
dc.identifier.issue21en_US
dc.identifier.spage6213en_US
dc.identifier.epage6217en_US
dc.identifier.isiWOS:A1984TN44500016-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridToi, H=6602135685en_US
dc.identifier.scopusauthoridLa Mar, GN=35462404100en_US
dc.identifier.scopusauthoridMargalit, R=7005792437en_US
dc.identifier.scopusauthoridChe, CM=7102442791en_US
dc.identifier.scopusauthoridGray, HB=36047602600en_US

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