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Gerothanassis IP, Momenteau M, Barrie PJ, et al. 13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data. Inorg Chem. 1996;35(9):2674-2679doi: 10.1021/ic950830r.
Gerothanassis, I. P., Momenteau, M., Barrie, P. J., Kalodimos, C. G., & Hawkes, G. E. (1996). 13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data. Inorganic chemistry, 35(9), 2674-2679. https://doi.org/10.1021/ic950830r
Gerothanassis, I. P., et al. "13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data." Inorganic chemistry vol. 35,9 (1996): 2674-2679. doi: https://doi.org/10.1021/ic950830r
Gerothanassis IP, Momenteau M, Barrie PJ, Kalodimos CG, Hawkes GE. 13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data. Inorg Chem. 1996 Apr 24;35(9):2674-2679. doi: 10.1021/ic950830r. PMID: 11666486.
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Inorg Chem. 1996 Apr 24;35(9):2674-2679. doi: 10.1021/ic950830r.

13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data.

Inorganic chemistry

I. P. Gerothanassis, M. Momenteau, P. J. Barrie, C. G. Kalodimos, G. E. Hawkes

Affiliations

  1. Department of Chemistry, Section of Organic Chemistry and Biochemistry, University of Ioannina, Ioannina GR-451 10, Greece, Institut Curie, Section de Recherche, URA 1387 CNRS, Centre Universitaire, 91405 Orsay, France, Department of Chemistry, University College London, 20 Gordon Street, London WC1H OAJ, U.K., and Department of Chemistry, Queen Mary and Westfield College, Mile End Road, London E1 4NS, U.K.

PMID: 11666486 DOI: 10.1021/ic950830r

Abstract

13C cross-polarization magic-angle-spinning (CP/MAS) NMR spectra of several carbonmonoxide (93-99% (13)C enriched) hemoprotein models with 1,2-dimethylimidazole (1,2-diMeIm) and 1-methylimidazole (1-MeIm) as axial ligands are reported. This enables the (13)CO spinning sideband manifold to be measured and hence the principal components of the (13)CO 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.

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