The Role of Heme Chirality in the Circular Dichroism of Heme Proteins
The rotational strength (R) of the Soret transition in sperm-whale myoglobin (SW Mb), the hemoglobin from Chirononms thummi thummi (C17 Hb), and human hemoglobin (hHb) has been calculated using 20 high-resolution (< 1.5 angstrom) crystal structures. The intrinsic rotational strength due to heme n...
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ftunivpisairis:oai:arpi.unipi.it:11568/596467 2024-04-21T08:12:22+00:00 The Role of Heme Chirality in the Circular Dichroism of Heme Proteins Woody, Robert W. PESCITELLI, GENNARO Woody, Robert W. Pescitelli, Gennaro 2014 STAMPA http://hdl.handle.net/11568/596467 https://doi.org/10.5560/ZNA.2014-0004 http://www.znaturforsch.com/aa/v69a/69a0313.htm eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000341556700006 volume:69a issue:7 firstpage:313 lastpage:325 numberofpages:13 journal:ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES http://hdl.handle.net/11568/596467 doi:10.5560/ZNA.2014-0004 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84989857831 http://www.znaturforsch.com/aa/v69a/69a0313.htm info:eu-repo/semantics/openAccess info:eu-repo/semantics/article 2014 ftunivpisairis https://doi.org/10.5560/ZNA.2014-0004 2024-03-28T01:23:04Z The rotational strength (R) of the Soret transition in sperm-whale myoglobin (SW Mb), the hemoglobin from Chirononms thummi thummi (C17 Hb), and human hemoglobin (hHb) has been calculated using 20 high-resolution (< 1.5 angstrom) crystal structures. The intrinsic rotational strength due to heme non-planarity was calculated using pi-electron theory and time-dependent density functional theory (TDDFT). Calculations on model protoporphyrins with a planar nucleus and with various torsional angles for the 2- and 4-vinyl substituents showed maximum R of +/- 0.70 Debye-Bohr magneton (1 DBM = 0.9273 . 10(-38) cgs units). Viewing the heme so that the 2- and 4-vinyls are in a counter-clockwise relationship, if a vinyl points toward the viewer, it contributes positively to R. Calculations of the intrinsic R for explicit heme geometries of SW Mb, CTT Hb, and hHb gave averages of 0.40 +/- 0.09, -0.44 +/- 0.04, and +0.32 +/- 0.11 DBM, respectively. Coupling of the Soret transition with aromatic side-chain and peptide backbone transitions was also considered. For SW Mb, the magnitudes of the contributions decreased in the order R-int > R-aro > R-pep. For CTT Hb and hHB, the orders were, respectively, R-int > R-pep > R-aro and R-int > R-aro approximate to R-pep. Human Hb alpha chains showed the same trend as CTT Hb. Only in the hHb beta chains did R-aro predominate, with the order R-aro > R-iot > R-pep. The total predicted R-tot for SW Mb, CTT Hb, and hHb averaged +0.77 +/- 0.10 (0.56-0.80), -0.37 +/- 0.12 (-0.5), and +0.31 +/- 0.17 DBM (0.23-0.50), respectively. (Values in parentheses are experimental values.) Thus, contrary to the currently accepted view, coupling with aromatic side-chain or peptide transitions is not the dominant factor in the Soret circular dichroism (CD) of these proteins. The Soret CD is dominated by intrinsic CD of the heme chromophore, of which vinyl torsion is the major determinant. This result suggests an explanation for the large effect of heme isomerism on the Soret CD of Mb ... Article in Journal/Newspaper Sperm whale ARPI - Archivio della Ricerca dell'Università di Pisa Zeitschrift für Naturforschung A 69 7 313 325 |
institution |
Open Polar |
collection |
ARPI - Archivio della Ricerca dell'Università di Pisa |
op_collection_id |
ftunivpisairis |
language |
English |
description |
The rotational strength (R) of the Soret transition in sperm-whale myoglobin (SW Mb), the hemoglobin from Chirononms thummi thummi (C17 Hb), and human hemoglobin (hHb) has been calculated using 20 high-resolution (< 1.5 angstrom) crystal structures. The intrinsic rotational strength due to heme non-planarity was calculated using pi-electron theory and time-dependent density functional theory (TDDFT). Calculations on model protoporphyrins with a planar nucleus and with various torsional angles for the 2- and 4-vinyl substituents showed maximum R of +/- 0.70 Debye-Bohr magneton (1 DBM = 0.9273 . 10(-38) cgs units). Viewing the heme so that the 2- and 4-vinyls are in a counter-clockwise relationship, if a vinyl points toward the viewer, it contributes positively to R. Calculations of the intrinsic R for explicit heme geometries of SW Mb, CTT Hb, and hHb gave averages of 0.40 +/- 0.09, -0.44 +/- 0.04, and +0.32 +/- 0.11 DBM, respectively. Coupling of the Soret transition with aromatic side-chain and peptide backbone transitions was also considered. For SW Mb, the magnitudes of the contributions decreased in the order R-int > R-aro > R-pep. For CTT Hb and hHB, the orders were, respectively, R-int > R-pep > R-aro and R-int > R-aro approximate to R-pep. Human Hb alpha chains showed the same trend as CTT Hb. Only in the hHb beta chains did R-aro predominate, with the order R-aro > R-iot > R-pep. The total predicted R-tot for SW Mb, CTT Hb, and hHb averaged +0.77 +/- 0.10 (0.56-0.80), -0.37 +/- 0.12 (-0.5), and +0.31 +/- 0.17 DBM (0.23-0.50), respectively. (Values in parentheses are experimental values.) Thus, contrary to the currently accepted view, coupling with aromatic side-chain or peptide transitions is not the dominant factor in the Soret circular dichroism (CD) of these proteins. The Soret CD is dominated by intrinsic CD of the heme chromophore, of which vinyl torsion is the major determinant. This result suggests an explanation for the large effect of heme isomerism on the Soret CD of Mb ... |
author2 |
Woody, Robert W. Pescitelli, Gennaro |
format |
Article in Journal/Newspaper |
author |
Woody, Robert W. PESCITELLI, GENNARO |
spellingShingle |
Woody, Robert W. PESCITELLI, GENNARO The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
author_facet |
Woody, Robert W. PESCITELLI, GENNARO |
author_sort |
Woody, Robert W. |
title |
The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
title_short |
The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
title_full |
The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
title_fullStr |
The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
title_full_unstemmed |
The Role of Heme Chirality in the Circular Dichroism of Heme Proteins |
title_sort |
role of heme chirality in the circular dichroism of heme proteins |
publishDate |
2014 |
url |
http://hdl.handle.net/11568/596467 https://doi.org/10.5560/ZNA.2014-0004 http://www.znaturforsch.com/aa/v69a/69a0313.htm |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000341556700006 volume:69a issue:7 firstpage:313 lastpage:325 numberofpages:13 journal:ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES http://hdl.handle.net/11568/596467 doi:10.5560/ZNA.2014-0004 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84989857831 http://www.znaturforsch.com/aa/v69a/69a0313.htm |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5560/ZNA.2014-0004 |
container_title |
Zeitschrift für Naturforschung A |
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69 |
container_issue |
7 |
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313 |
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325 |
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