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Systematic Tuning of Heme Redox Potentials and Its Effects on O(2) Reduction Rates in a Designed Oxidase in Myoglobin
[Image: see text] Cytochrome c Oxidase (CcO) is known to catalyze the reduction of O(2) to H(2)O efficiently with a much lower overpotential than most other O(2) reduction catalysts. However, methods by which the enzyme fine-tunes the reduction potential (E°) of its active site and the corresponding...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical
Society
2014
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4151708/ https://www.ncbi.nlm.nih.gov/pubmed/25076049 http://dx.doi.org/10.1021/ja5054863 |
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author | Bhagi-Damodaran, Ambika Petrik, Igor D. Marshall, Nicholas M. Robinson, Howard Lu, Yi |
author_facet | Bhagi-Damodaran, Ambika Petrik, Igor D. Marshall, Nicholas M. Robinson, Howard Lu, Yi |
author_sort | Bhagi-Damodaran, Ambika |
collection | PubMed |
description | [Image: see text] Cytochrome c Oxidase (CcO) is known to catalyze the reduction of O(2) to H(2)O efficiently with a much lower overpotential than most other O(2) reduction catalysts. However, methods by which the enzyme fine-tunes the reduction potential (E°) of its active site and the corresponding influence on the O(2) reduction activity are not well understood. In this work, we report systematic tuning of the heme E° in a functional model of CcO in myoglobin containing three histidines and one tyrosine in the distal pocket of heme. By removing hydrogen-bonding interactions between Ser92 and the proximal His ligand and a heme propionate, and increasing hydrophobicity of the heme pocket through Ser92Ala mutation, we have increased the heme E° from 95 ± 2 to 123 ± 3 mV. Additionally, replacing the native heme b in the CcO mimic with heme a analogs, diacetyl, monoformyl, and diformyl hemes, that posses electron-withdrawing groups, resulted in higher E° values of 175 ± 5, 210 ± 6, and 320 ± 10 mV, respectively. Furthermore, O(2) consumption studies on these CcO mimics revealed a strong enhancement in O(2) reduction rates with increasing heme E°. Such methods of tuning the heme E° through a combination of secondary sphere mutations and heme substitutions can be applied to tune E° of other heme proteins, allowing for comprehensive investigations of the relationship between E° and enzymatic activity. |
format | Online Article Text |
id | pubmed-4151708 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2014 |
publisher | American Chemical
Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-41517082015-07-30 Systematic Tuning of Heme Redox Potentials and Its Effects on O(2) Reduction Rates in a Designed Oxidase in Myoglobin Bhagi-Damodaran, Ambika Petrik, Igor D. Marshall, Nicholas M. Robinson, Howard Lu, Yi J Am Chem Soc [Image: see text] Cytochrome c Oxidase (CcO) is known to catalyze the reduction of O(2) to H(2)O efficiently with a much lower overpotential than most other O(2) reduction catalysts. However, methods by which the enzyme fine-tunes the reduction potential (E°) of its active site and the corresponding influence on the O(2) reduction activity are not well understood. In this work, we report systematic tuning of the heme E° in a functional model of CcO in myoglobin containing three histidines and one tyrosine in the distal pocket of heme. By removing hydrogen-bonding interactions between Ser92 and the proximal His ligand and a heme propionate, and increasing hydrophobicity of the heme pocket through Ser92Ala mutation, we have increased the heme E° from 95 ± 2 to 123 ± 3 mV. Additionally, replacing the native heme b in the CcO mimic with heme a analogs, diacetyl, monoformyl, and diformyl hemes, that posses electron-withdrawing groups, resulted in higher E° values of 175 ± 5, 210 ± 6, and 320 ± 10 mV, respectively. Furthermore, O(2) consumption studies on these CcO mimics revealed a strong enhancement in O(2) reduction rates with increasing heme E°. Such methods of tuning the heme E° through a combination of secondary sphere mutations and heme substitutions can be applied to tune E° of other heme proteins, allowing for comprehensive investigations of the relationship between E° and enzymatic activity. American Chemical Society 2014-07-30 2014-08-27 /pmc/articles/PMC4151708/ /pubmed/25076049 http://dx.doi.org/10.1021/ja5054863 Text en Copyright © 2014 American Chemical Society Terms of Use (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) |
spellingShingle | Bhagi-Damodaran, Ambika Petrik, Igor D. Marshall, Nicholas M. Robinson, Howard Lu, Yi Systematic Tuning of Heme Redox Potentials and Its Effects on O(2) Reduction Rates in a Designed Oxidase in Myoglobin |
title | Systematic
Tuning of Heme Redox Potentials and Its
Effects on O(2) Reduction Rates in a Designed Oxidase in
Myoglobin |
title_full | Systematic
Tuning of Heme Redox Potentials and Its
Effects on O(2) Reduction Rates in a Designed Oxidase in
Myoglobin |
title_fullStr | Systematic
Tuning of Heme Redox Potentials and Its
Effects on O(2) Reduction Rates in a Designed Oxidase in
Myoglobin |
title_full_unstemmed | Systematic
Tuning of Heme Redox Potentials and Its
Effects on O(2) Reduction Rates in a Designed Oxidase in
Myoglobin |
title_short | Systematic
Tuning of Heme Redox Potentials and Its
Effects on O(2) Reduction Rates in a Designed Oxidase in
Myoglobin |
title_sort | systematic
tuning of heme redox potentials and its
effects on o(2) reduction rates in a designed oxidase in
myoglobin |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4151708/ https://www.ncbi.nlm.nih.gov/pubmed/25076049 http://dx.doi.org/10.1021/ja5054863 |
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