The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin
To probe the role of copper and protons in heme-copper oxidase (HCO), we have performed kinetic studies on an engineered heme-copper center in sperm whale myoglobin (Leu-29 → His/Phe-43 → His, called CuBMb) that closely mimics the heme-copper center in HCO. In the absence of metal ions, the engineer...
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ftpubmed:oai:pubmedcentral.nih.gov:152973 2023-05-15T18:26:49+02:00 The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin Sigman, Jeffrey A. Kim, Hyeon K. Zhao, Xuan Carey, James R. Lu, Yi 2003-04-01 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC152973 http://www.ncbi.nlm.nih.gov/pubmed/12655052 https://doi.org/10.1073/pnas.0737308100 en eng The National Academy of Sciences http://www.ncbi.nlm.nih.gov/pmc/articles/PMC152973 http://www.ncbi.nlm.nih.gov/pubmed/12655052 http://dx.doi.org/10.1073/pnas.0737308100 Copyright © 2003, The National Academy of Sciences Physical Sciences Text 2003 ftpubmed https://doi.org/10.1073/pnas.0737308100 2013-08-29T11:55:53Z To probe the role of copper and protons in heme-copper oxidase (HCO), we have performed kinetic studies on an engineered heme-copper center in sperm whale myoglobin (Leu-29 → His/Phe-43 → His, called CuBMb) that closely mimics the heme-copper center in HCO. In the absence of metal ions, the engineered CuB center in CuBMb decreases the O2 binding affinity of the heme. However, addition of Ag(I), a redox-inactive mimic of Cu(I), increases the O2-binding affinity. More importantly, copper ion in the CuB center is essential for O2 reduction, as no O2 reduction can be observed in copper-free, Zn(II), or Ag(I) derivatives of CuBMb. Instead of producing a ferryl-heme as in HCO, the CuBMb generates verdoheme because the engineered CuBMb may lack a hydrogen bonding network that delivers protons to promote the heterolytic O—O cleavage necessary for the formation of ferryl-heme. Reaction of oxidized CuBMb with H2O2, a species equivalent in oxidation state to 2e−, reduced O2 but, possessing the extra protons, resulted in ferryl-heme formation, as in HCO. The results showed that the CuB center plays a critical role in O2 binding and reduction, and that proton delivery during the O2 reduction is important to avoid heme degradation and to promote the HCO reaction. Text Sperm whale PubMed Central (PMC) Proceedings of the National Academy of Sciences 100 7 3629 3634 |
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Physical Sciences Sigman, Jeffrey A. Kim, Hyeon K. Zhao, Xuan Carey, James R. Lu, Yi The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
topic_facet |
Physical Sciences |
description |
To probe the role of copper and protons in heme-copper oxidase (HCO), we have performed kinetic studies on an engineered heme-copper center in sperm whale myoglobin (Leu-29 → His/Phe-43 → His, called CuBMb) that closely mimics the heme-copper center in HCO. In the absence of metal ions, the engineered CuB center in CuBMb decreases the O2 binding affinity of the heme. However, addition of Ag(I), a redox-inactive mimic of Cu(I), increases the O2-binding affinity. More importantly, copper ion in the CuB center is essential for O2 reduction, as no O2 reduction can be observed in copper-free, Zn(II), or Ag(I) derivatives of CuBMb. Instead of producing a ferryl-heme as in HCO, the CuBMb generates verdoheme because the engineered CuBMb may lack a hydrogen bonding network that delivers protons to promote the heterolytic O—O cleavage necessary for the formation of ferryl-heme. Reaction of oxidized CuBMb with H2O2, a species equivalent in oxidation state to 2e−, reduced O2 but, possessing the extra protons, resulted in ferryl-heme formation, as in HCO. The results showed that the CuB center plays a critical role in O2 binding and reduction, and that proton delivery during the O2 reduction is important to avoid heme degradation and to promote the HCO reaction. |
format |
Text |
author |
Sigman, Jeffrey A. Kim, Hyeon K. Zhao, Xuan Carey, James R. Lu, Yi |
author_facet |
Sigman, Jeffrey A. Kim, Hyeon K. Zhao, Xuan Carey, James R. Lu, Yi |
author_sort |
Sigman, Jeffrey A. |
title |
The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
title_short |
The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
title_full |
The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
title_fullStr |
The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
title_full_unstemmed |
The role of copper and protons in heme-copper oxidases: Kinetic study of an engineered heme-copper center in myoglobin |
title_sort |
role of copper and protons in heme-copper oxidases: kinetic study of an engineered heme-copper center in myoglobin |
publisher |
The National Academy of Sciences |
publishDate |
2003 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC152973 http://www.ncbi.nlm.nih.gov/pubmed/12655052 https://doi.org/10.1073/pnas.0737308100 |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC152973 http://www.ncbi.nlm.nih.gov/pubmed/12655052 http://dx.doi.org/10.1073/pnas.0737308100 |
op_rights |
Copyright © 2003, The National Academy of Sciences |
op_doi |
https://doi.org/10.1073/pnas.0737308100 |
container_title |
Proceedings of the National Academy of Sciences |
container_volume |
100 |
container_issue |
7 |
container_start_page |
3629 |
op_container_end_page |
3634 |
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1766208781952221184 |