1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins
The 1H and 13C chemical shifts for the heme methyls of low-spin, ferric sperm whale cyanometmyoglobin reconstituted with a variety of centrosymmetric and pseudocentrosymmetric hemins have been recorded and analyzed to shed light on the nature of heme-protein contacts, other than that of the axial Hi...
Published in: | Journal of the American Chemical Society |
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2001
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Online Access: | https://digitalcommons.lsu.edu/chemistry_pubs/1630 https://doi.org/10.1021/ja011175r |
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ftlouisianastuir:oai:digitalcommons.lsu.edu:chemistry_pubs-2631 2023-06-11T04:17:07+02:00 1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins Hu, B. Hauksson, J. B. Tran, A. T.T. Kolczak, U. Pandey, R. K. Rezzano, I. N. Smith, K. M. La Mar, G. N. 2001-10-17T07:00:00Z https://digitalcommons.lsu.edu/chemistry_pubs/1630 https://doi.org/10.1021/ja011175r unknown LSU Digital Commons https://digitalcommons.lsu.edu/chemistry_pubs/1630 doi:10.1021/ja011175r Faculty Publications text 2001 ftlouisianastuir https://doi.org/10.1021/ja011175r 2023-05-28T18:15:09Z The 1H and 13C chemical shifts for the heme methyls of low-spin, ferric sperm whale cyanometmyoglobin reconstituted with a variety of centrosymmetric and pseudocentrosymmetric hemins have been recorded and analyzed to shed light on the nature of heme-protein contacts, other than that of the axial His, that modulate the rhombic perturbation to the heme's in-plane electronic asymmetry. The very similar 1H dipolar shifts for heme pocket residues in all complexes yield essentially the same magnetic axes as in wild type, and the resultant dipolar shifts allow the direct determination of the heme methyl proton and 13C contact shifts in all complexes. It is demonstrated that, even when the magnetic axes and anisotropies are known, the intrinsic uncertainties in the orientational parameters lead to a sufficiently large uncertainty in dipolar shift that the methyl proton contact shifts are inherently significantly less reliable indicators of the unpaired electron spin distribution than the methyl 13C contact shifts. The pattern of the noninversion symmetry in 13C contact shifts in the centro- or pseudocentrosymmetric hemes is shown to correlate with the positions of aromatic rings of Phe43(CD1) and His97(FG3) parallel to, and in contact with, the heme. These results indicate that such π-π interactions significantly perturb the in-plane asymmetry of the heme π spin distribution and cannot be ignored in a quantitative interpretation of the heme methyl 13C contact shifts in terms of the axial His orientation in b-type hemoproteins. Text Sperm whale LSU Digital Commons (Louisiana State University) Journal of the American Chemical Society 123 41 10063 10070 |
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LSU Digital Commons (Louisiana State University) |
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ftlouisianastuir |
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unknown |
description |
The 1H and 13C chemical shifts for the heme methyls of low-spin, ferric sperm whale cyanometmyoglobin reconstituted with a variety of centrosymmetric and pseudocentrosymmetric hemins have been recorded and analyzed to shed light on the nature of heme-protein contacts, other than that of the axial His, that modulate the rhombic perturbation to the heme's in-plane electronic asymmetry. The very similar 1H dipolar shifts for heme pocket residues in all complexes yield essentially the same magnetic axes as in wild type, and the resultant dipolar shifts allow the direct determination of the heme methyl proton and 13C contact shifts in all complexes. It is demonstrated that, even when the magnetic axes and anisotropies are known, the intrinsic uncertainties in the orientational parameters lead to a sufficiently large uncertainty in dipolar shift that the methyl proton contact shifts are inherently significantly less reliable indicators of the unpaired electron spin distribution than the methyl 13C contact shifts. The pattern of the noninversion symmetry in 13C contact shifts in the centro- or pseudocentrosymmetric hemes is shown to correlate with the positions of aromatic rings of Phe43(CD1) and His97(FG3) parallel to, and in contact with, the heme. These results indicate that such π-π interactions significantly perturb the in-plane asymmetry of the heme π spin distribution and cannot be ignored in a quantitative interpretation of the heme methyl 13C contact shifts in terms of the axial His orientation in b-type hemoproteins. |
format |
Text |
author |
Hu, B. Hauksson, J. B. Tran, A. T.T. Kolczak, U. Pandey, R. K. Rezzano, I. N. Smith, K. M. La Mar, G. N. |
spellingShingle |
Hu, B. Hauksson, J. B. Tran, A. T.T. Kolczak, U. Pandey, R. K. Rezzano, I. N. Smith, K. M. La Mar, G. N. 1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
author_facet |
Hu, B. Hauksson, J. B. Tran, A. T.T. Kolczak, U. Pandey, R. K. Rezzano, I. N. Smith, K. M. La Mar, G. N. |
author_sort |
Hu, B. |
title |
1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
title_short |
1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
title_full |
1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
title_fullStr |
1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
title_full_unstemmed |
1 H and 13 C NMR investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
title_sort |
1 h and 13 c nmr investigation of the influence of nonligated residue contacts on the heme electronic structure in cyanometmyoglobin complexes reconstituted with centro- and pseudocentrosymmetric hemins |
publisher |
LSU Digital Commons |
publishDate |
2001 |
url |
https://digitalcommons.lsu.edu/chemistry_pubs/1630 https://doi.org/10.1021/ja011175r |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
Faculty Publications |
op_relation |
https://digitalcommons.lsu.edu/chemistry_pubs/1630 doi:10.1021/ja011175r |
op_doi |
https://doi.org/10.1021/ja011175r |
container_title |
Journal of the American Chemical Society |
container_volume |
123 |
container_issue |
41 |
container_start_page |
10063 |
op_container_end_page |
10070 |
_version_ |
1768375967135301632 |