Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin
Nitrite binding to recombinant wild-type Sperm Whale myoglobin (SWMb) was studied using a combination of spectroscopic methods including room-temperature magnetic circular dichroism. These revealed that the reactive species is free nitrous acid and the product of the reaction contains a nitrite ion...
Published in: | Biochemical Journal |
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2021
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Online Access: | https://ueaeprints.uea.ac.uk/id/eprint/79380/ https://ueaeprints.uea.ac.uk/id/eprint/79380/1/Published_Version.pdf https://doi.org/10.1042/BCJ20200596 |
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ftuniveastangl:oai:ueaeprints.uea.ac.uk:79380 2023-05-15T18:26:39+02:00 Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin Tse, Wilford Whitmore, Nathan Cheesman, Myles R. Watmough, Nicholas J. 2021-02-26 application/pdf https://ueaeprints.uea.ac.uk/id/eprint/79380/ https://ueaeprints.uea.ac.uk/id/eprint/79380/1/Published_Version.pdf https://doi.org/10.1042/BCJ20200596 en eng https://ueaeprints.uea.ac.uk/id/eprint/79380/1/Published_Version.pdf Tse, Wilford, Whitmore, Nathan, Cheesman, Myles R. and Watmough, Nicholas J. (2021) Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin. Biochemical Journal, 478 (4). pp. 927-942. ISSN 0264-6021 doi:10.1042/BCJ20200596 cc_by CC-BY Article PeerReviewed 2021 ftuniveastangl https://doi.org/10.1042/BCJ20200596 2023-01-30T21:54:41Z Nitrite binding to recombinant wild-type Sperm Whale myoglobin (SWMb) was studied using a combination of spectroscopic methods including room-temperature magnetic circular dichroism. These revealed that the reactive species is free nitrous acid and the product of the reaction contains a nitrite ion bound to the ferric heme iron in the nitrito- (O-bound) orientation. This exists in a thermal equilibrium with a low-spin ground state and a high-spin excited state and is spectroscopically distinct from the purely low-spin nitro- (N-bound) species observed in the H64V SWMb variant. Substitution of the proximal heme ligand, histidine-93, with lysine yields a novel form of myoglobin (H93K) with enhanced reactivity towards nitrite. The nitrito-mode of binding to the ferric heme iron is retained in the H93K variant again as a thermal equilibrium of spin-states. This proximal substitution influences the heme distal pocket causing the pKa of the alkaline transition to be lowered relative to wild-type SWMb. This change in the environment of the distal pocket coupled with nitrito-binding is the most likely explanation for the 8-fold increase in the rate of nitrite reduction by H93K relative to WT SWMb. Article in Journal/Newspaper Sperm whale University of East Anglia: UEA Digital Repository Biochemical Journal 478 4 927 942 |
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University of East Anglia: UEA Digital Repository |
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ftuniveastangl |
language |
English |
description |
Nitrite binding to recombinant wild-type Sperm Whale myoglobin (SWMb) was studied using a combination of spectroscopic methods including room-temperature magnetic circular dichroism. These revealed that the reactive species is free nitrous acid and the product of the reaction contains a nitrite ion bound to the ferric heme iron in the nitrito- (O-bound) orientation. This exists in a thermal equilibrium with a low-spin ground state and a high-spin excited state and is spectroscopically distinct from the purely low-spin nitro- (N-bound) species observed in the H64V SWMb variant. Substitution of the proximal heme ligand, histidine-93, with lysine yields a novel form of myoglobin (H93K) with enhanced reactivity towards nitrite. The nitrito-mode of binding to the ferric heme iron is retained in the H93K variant again as a thermal equilibrium of spin-states. This proximal substitution influences the heme distal pocket causing the pKa of the alkaline transition to be lowered relative to wild-type SWMb. This change in the environment of the distal pocket coupled with nitrito-binding is the most likely explanation for the 8-fold increase in the rate of nitrite reduction by H93K relative to WT SWMb. |
format |
Article in Journal/Newspaper |
author |
Tse, Wilford Whitmore, Nathan Cheesman, Myles R. Watmough, Nicholas J. |
spellingShingle |
Tse, Wilford Whitmore, Nathan Cheesman, Myles R. Watmough, Nicholas J. Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
author_facet |
Tse, Wilford Whitmore, Nathan Cheesman, Myles R. Watmough, Nicholas J. |
author_sort |
Tse, Wilford |
title |
Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
title_short |
Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
title_full |
Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
title_fullStr |
Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
title_full_unstemmed |
Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin |
title_sort |
influence of the heme distal pocket on nitrite binding orientation and reactivity in sperm whale myoglobin |
publishDate |
2021 |
url |
https://ueaeprints.uea.ac.uk/id/eprint/79380/ https://ueaeprints.uea.ac.uk/id/eprint/79380/1/Published_Version.pdf https://doi.org/10.1042/BCJ20200596 |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
https://ueaeprints.uea.ac.uk/id/eprint/79380/1/Published_Version.pdf Tse, Wilford, Whitmore, Nathan, Cheesman, Myles R. and Watmough, Nicholas J. (2021) Influence of the heme distal pocket on nitrite binding orientation and reactivity in Sperm Whale myoglobin. Biochemical Journal, 478 (4). pp. 927-942. ISSN 0264-6021 doi:10.1042/BCJ20200596 |
op_rights |
cc_by |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1042/BCJ20200596 |
container_title |
Biochemical Journal |
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478 |
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4 |
container_start_page |
927 |
op_container_end_page |
942 |
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1766208619056988160 |