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Insights into the P-to-Q conversion in the catalytic cycle of methane monooxygenase from a synthetic model system.

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Title: Insights into the P-to-Q conversion in the catalytic cycle of methane monooxygenase from a synthetic model system.
Authors: Genqiang Xue1, Fiedler, Adam T.1, Martinho, Marlene2, Münck, Eckard2 emunck@cmu.edu, Que Jr, Lawrence1 larryque@umn.edu
Source: Proceedings of the National Academy of Sciences of the United States of America. 12/30/2008, Vol. 105 Issue 52, p20615-20620. 6p. 4 Diagrams, 1 Chart, 5 Graphs.
Subjects: Methane, Monooxygenases, Oxygenases, Organic compounds, Physical & theoretical chemistry
Abstract: For the catalytic cycle of soluble methane monooxygenase (sMMO), it has been proposed that cleavage of the O-O bond in the (µ-peroxo)diiron(lll) intermediate P gives rise to the diiron(IV) intermediate Q with an Fe2(µ-O)2 diamond core, which oxidizes methane to methanol. As a model for this conversion, (µ-oxo)-diiron(lll) complex 1 ([FeIII2(µ-O)(µ-O2H3)(L)2]3+, L = tris(3,5-dimethyl-4-methoxypyridyl-2-methyl)amine) has been treated consecutively with one eq of H2O2 and one eq of HClO4 to form 3 ([FeIV2(µ-O)2(L)2]4+). In the course of this reaction a new species, 2, can be observed before the protonation step; 2 gives rise to a cationic peak cluster by ESl-MS at m/z 1,399, corresponding to the {[Fe2O3L2H](OTf)2}+ ion in which 1 oxygen atom derives from 1 and the other two originate from H2O2. Mössbauer studies of 2 reveal the presence of two distinct, exchange coupled iron(IV) centers, and EXAFS fits indicate a short Fe-O bond at 1.66 Å and an Fe-Fe distance of 3.32 Å. Taken together, the spectroscopic data point to an HO-FeIV-O-FeIV = O core for 2. Protonation of 2 results in the loss of H2O and the formation of 3. Isotope labeling experiments show that the [FeIV2(µ-O)2] core of 3 can incorporate both oxygen atoms from H2O2. The reactions described here serve as the only biomimetic precedent for the conversion of intermediates P to Q in the sMMO reaction cycle and shed light on how a peroxodiiron(lll) unit can transform into an [FeIV2(µ-O)2] core. [ABSTRACT FROM AUTHOR]
Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: Insights into the P-to-Q conversion in the catalytic cycle of methane monooxygenase from a synthetic model system.
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  Data: <searchLink fieldCode="AR" term="%22Genqiang+Xue%22">Genqiang Xue</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Fiedler%2C+Adam+T%2E%22">Fiedler, Adam T.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Martinho%2C+Marlene%22">Martinho, Marlene</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Münck%2C+Eckard%22">Münck, Eckard</searchLink><relatesTo>2</relatesTo><i> emunck@cmu.edu</i><br /><searchLink fieldCode="AR" term="%22Que+Jr%2C+Lawrence%22">Que Jr, Lawrence</searchLink><relatesTo>1</relatesTo><i> larryque@umn.edu</i>
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  Data: <searchLink fieldCode="DE" term="%22Methane%22">Methane</searchLink><br /><searchLink fieldCode="DE" term="%22Monooxygenases%22">Monooxygenases</searchLink><br /><searchLink fieldCode="DE" term="%22Oxygenases%22">Oxygenases</searchLink><br /><searchLink fieldCode="DE" term="%22Organic+compounds%22">Organic compounds</searchLink><br /><searchLink fieldCode="DE" term="%22Physical+%26+theoretical+chemistry%22">Physical & theoretical chemistry</searchLink>
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  Data: For the catalytic cycle of soluble methane monooxygenase (sMMO), it has been proposed that cleavage of the O-O bond in the (µ-peroxo)diiron(lll) intermediate P gives rise to the diiron(IV) intermediate Q with an Fe2(µ-O)2 diamond core, which oxidizes methane to methanol. As a model for this conversion, (µ-oxo)-diiron(lll) complex 1 ([FeIII2(µ-O)(µ-O2H3)(L)2]3+, L = tris(3,5-dimethyl-4-methoxypyridyl-2-methyl)amine) has been treated consecutively with one eq of H2O2 and one eq of HClO4 to form 3 ([FeIV2(µ-O)2(L)2]4+). In the course of this reaction a new species, 2, can be observed before the protonation step; 2 gives rise to a cationic peak cluster by ESl-MS at m/z 1,399, corresponding to the {[Fe2O3L2H](OTf)2}+ ion in which 1 oxygen atom derives from 1 and the other two originate from H2O2. Mössbauer studies of 2 reveal the presence of two distinct, exchange coupled iron(IV) centers, and EXAFS fits indicate a short Fe-O bond at 1.66 Å and an Fe-Fe distance of 3.32 Å. Taken together, the spectroscopic data point to an HO-FeIV-O-FeIV = O core for 2. Protonation of 2 results in the loss of H2O and the formation of 3. Isotope labeling experiments show that the [FeIV2(µ-O)2] core of 3 can incorporate both oxygen atoms from H2O2. The reactions described here serve as the only biomimetic precedent for the conversion of intermediates P to Q in the sMMO reaction cycle and shed light on how a peroxodiiron(lll) unit can transform into an [FeIV2(µ-O)2] core. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
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  Data: <i>Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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        Value: 10.1073/pnas.0808512105
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        Text: English
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        StartPage: 20615
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        Type: general
      – SubjectFull: Monooxygenases
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      – SubjectFull: Oxygenases
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      – SubjectFull: Organic compounds
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      – SubjectFull: Physical & theoretical chemistry
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      – TitleFull: Insights into the P-to-Q conversion in the catalytic cycle of methane monooxygenase from a synthetic model system.
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            NameFull: Genqiang Xue
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              Text: 12/30/2008
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