Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin
The oxygenated form of myoglobin or hemoglobin is oxidized easily to the ferric met‐form with generation of the superoxide anion. To make clear the possible role(s) of the distal histidine (H64) residue in the reaction, we have carried out detailed pH‐dependence studies of the autoxidation rate, usi...
Published in: | European Journal of Biochemistry |
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Online Access: | http://dx.doi.org/10.1046/j.1432-1327.2000.01685.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1432-1327.2000.01685.x https://febs.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1432-1327.2000.01685.x |
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crwiley:10.1046/j.1432-1327.2000.01685.x 2024-06-02T08:14:52+00:00 Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin Comparison of the H64 mutants Suzuki, Tatsuya Watanabe, Yo‐hei Nagasawa, Masashi Matsuoka, Ariki Shikama, Keiji 2000 http://dx.doi.org/10.1046/j.1432-1327.2000.01685.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1432-1327.2000.01685.x https://febs.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1432-1327.2000.01685.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor European Journal of Biochemistry volume 267, issue 20, page 6166-6174 ISSN 0014-2956 1432-1033 journal-article 2000 crwiley https://doi.org/10.1046/j.1432-1327.2000.01685.x 2024-05-03T11:18:00Z The oxygenated form of myoglobin or hemoglobin is oxidized easily to the ferric met‐form with generation of the superoxide anion. To make clear the possible role(s) of the distal histidine (H64) residue in the reaction, we have carried out detailed pH‐dependence studies of the autoxidation rate, using some typical H64 mutants of sperm whale myoglobin, over the wide range of pH 5–12 in 0.1 m buffer at 25 °C. Each mutation caused a dramatic increase in the autoxidation rate with the trend H64V ≥ H64G ≥ H64L ≫ H64Q > H64 (wild‐type) at pH 7.0, whereas each mutant protein showed a characteristic pH‐profile which is essentially different from that of the wild‐type or native sperm whale MbO 2 . In particular, all the mutants have lost the acid‐catalyzed process that can play a dominant role in the autoxidation reaction of most mammalian myoglobins or hemoglobins. Kinetic analyses of various types of pH‐profiles lead us to conclude that the distal histidine residue can play a dual role in the nucleophilic displacement of O 2 − from MbO 2 or HbO 2 in protic, aqueous solution. One is in a proton‐relay mechanism via its imidazole ring, and the other is in the maximum protection of the FeO 2 center against a water molecule or an hydroxyl ion that can enter the heme pocket from the surrounding solvent. Article in Journal/Newspaper Sperm whale Wiley Online Library European Journal of Biochemistry 267 20 6166 6174 |
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Wiley Online Library |
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language |
English |
description |
The oxygenated form of myoglobin or hemoglobin is oxidized easily to the ferric met‐form with generation of the superoxide anion. To make clear the possible role(s) of the distal histidine (H64) residue in the reaction, we have carried out detailed pH‐dependence studies of the autoxidation rate, using some typical H64 mutants of sperm whale myoglobin, over the wide range of pH 5–12 in 0.1 m buffer at 25 °C. Each mutation caused a dramatic increase in the autoxidation rate with the trend H64V ≥ H64G ≥ H64L ≫ H64Q > H64 (wild‐type) at pH 7.0, whereas each mutant protein showed a characteristic pH‐profile which is essentially different from that of the wild‐type or native sperm whale MbO 2 . In particular, all the mutants have lost the acid‐catalyzed process that can play a dominant role in the autoxidation reaction of most mammalian myoglobins or hemoglobins. Kinetic analyses of various types of pH‐profiles lead us to conclude that the distal histidine residue can play a dual role in the nucleophilic displacement of O 2 − from MbO 2 or HbO 2 in protic, aqueous solution. One is in a proton‐relay mechanism via its imidazole ring, and the other is in the maximum protection of the FeO 2 center against a water molecule or an hydroxyl ion that can enter the heme pocket from the surrounding solvent. |
format |
Article in Journal/Newspaper |
author |
Suzuki, Tatsuya Watanabe, Yo‐hei Nagasawa, Masashi Matsuoka, Ariki Shikama, Keiji |
spellingShingle |
Suzuki, Tatsuya Watanabe, Yo‐hei Nagasawa, Masashi Matsuoka, Ariki Shikama, Keiji Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
author_facet |
Suzuki, Tatsuya Watanabe, Yo‐hei Nagasawa, Masashi Matsuoka, Ariki Shikama, Keiji |
author_sort |
Suzuki, Tatsuya |
title |
Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
title_short |
Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
title_full |
Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
title_fullStr |
Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
title_full_unstemmed |
Dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
title_sort |
dual nature of the distal histidine residue in the autoxidation reaction of myoglobin and hemoglobin |
publisher |
Wiley |
publishDate |
2000 |
url |
http://dx.doi.org/10.1046/j.1432-1327.2000.01685.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1432-1327.2000.01685.x https://febs.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1432-1327.2000.01685.x |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
European Journal of Biochemistry volume 267, issue 20, page 6166-6174 ISSN 0014-2956 1432-1033 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1046/j.1432-1327.2000.01685.x |
container_title |
European Journal of Biochemistry |
container_volume |
267 |
container_issue |
20 |
container_start_page |
6166 |
op_container_end_page |
6174 |
_version_ |
1800738876807970816 |