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
Φόρτωση...
Ημερομηνία
Συγγραφείς
Gerothanassis, I. P.
Momenteau, M.
Barrie, P. J.
Kalodimos, C. G.
Hawkes, G. E.
Τίτλος Εφημερίδας
Περιοδικό ISSN
Τίτλος τόμου
Εκδότης
American Chemical Society
Περίληψη
Τύπος
Είδος δημοσίευσης σε συνέδριο
Είδος περιοδικού
peer reviewed
Είδος εκπαιδευτικού υλικού
Όνομα συνεδρίου
Όνομα περιοδικού
Inorg Chem
Όνομα βιβλίου
Σειρά βιβλίου
Έκδοση βιβλίου
Συμπληρωματικός/δευτερεύων τίτλος
Περιγραφή
C-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.
Περιγραφή
Λέξεις-κλειδιά
resonance raman-spectroscopy, oxygen-binding hemoproteins, nuclear-magnetic-resonance, heme-proteins, capped porphyrin, carbon-monoxide, co binding, pocket porphyrins, iron-porphyrins, chemical-shifts
Θεματική κατηγορία
Παραπομπή
Σύνδεσμος
<Go to ISI>://A1996UH03300040
http://pubs.acs.org/doi/pdfplus/10.1021/ic950830r
http://pubs.acs.org/doi/pdfplus/10.1021/ic950830r
Γλώσσα
en
Εκδίδον τμήμα/τομέας
Όνομα επιβλέποντος
Εξεταστική επιτροπή
Γενική Περιγραφή / Σχόλια
Ίδρυμα και Σχολή/Τμήμα του υποβάλλοντος
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας