C-13 CP/MAS NMR studies of hemoprotein models with and without an axial hindered base: C-13 shielding tensors and comparison with hemoproteins and X-ray structural data

dc.contributor.authorGerothanassis, I. P.en
dc.contributor.authorMomenteau, M.en
dc.contributor.authorBarrie, P. J.en
dc.contributor.authorKalodimos, C. G.en
dc.contributor.authorHawkes, G. E.en
dc.date.accessioned2015-11-24T16:53:19Z
dc.date.available2015-11-24T16:53:19Z
dc.identifier.issn0020-1669-
dc.identifier.urihttps://olympias.lib.uoi.gr/jspui/handle/123456789/10002
dc.rightsDefault Licence-
dc.subjectresonance raman-spectroscopyen
dc.subjectoxygen-binding hemoproteinsen
dc.subjectnuclear-magnetic-resonanceen
dc.subjectheme-proteinsen
dc.subjectcapped porphyrinen
dc.subjectcarbon-monoxideen
dc.subjectco bindingen
dc.subjectpocket porphyrinsen
dc.subjectiron-porphyrinsen
dc.subjectchemical-shiftsen
dc.titleC-13 CP/MAS NMR studies of hemoprotein models with and without an axial hindered base: C-13 shielding tensors and comparison with hemoproteins and X-ray structural dataen
heal.abstractC-13 cross-polarization magic-angle-spinning (CP/MAS) NMR spectra of several carbonmonoxide (93-99% C-13 enriched) hemoprotein models with 1,2-dimethylimidazole (12-diMeIm) and 1-methylimidazole (1-MeIm) as axial ligands are reported. This enables the (CO)-C-13 spinning sideband manifold to be measured and hence the principal components of the (CO)-C-13 chemical shift tensor to be obtained. Negative polar interactions in the binding pocket of the cap porphyrin model and inhibition of Fe-->CO back-donation result in a reduction in shielding anisotropy; on the contrary, positive distal polar interactions result in an increase in the shielding anisotropy and asymmetry parameter in some models. It appears that the axial hindered base 1,2-dimethylimidazole has little direct effect on the local geometry at the CO site, despite higher rates of CO desorption being observed for such complexes. This suggests that the mechanism by which steric interactions are released for the 1,2-diMeIm complexes compared to 1-MeIm complexes does not involve a significant increase in bending of the Fe-C-O unit. The asymmetry of the shielding tensor of all the heme model compounds studied is smaller than that found for horse myoglobin and rabbit hemoglobin.en
heal.accesscampus-
heal.fullTextAvailabilityTRUE-
heal.identifier.secondary<Go to ISI>://A1996UH03300040-
heal.identifier.secondaryhttp://pubs.acs.org/doi/pdfplus/10.1021/ic950830r-
heal.journalNameInorg Chemen
heal.journalTypepeer reviewed-
heal.languageen-
heal.publicationDate1996-
heal.publisherAmerican Chemical Societyen
heal.recordProviderΠανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείαςel
heal.typejournalArticle-
heal.type.elΆρθρο Περιοδικούel
heal.type.enJournal articleen

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