What question did this study set out to answer?

To identify and spectroscopically characterize the proposed transient isoporphyrin intermediate during the initial oxygenation step of heme degradation catalyzed by human heme oxygenase-1.

May 17, 2008Journal of Biological ChemistryOpen Access

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

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Authors

JEJohn P. EvansThe Ohio State University FNFernando NiemevzUniversity of Buenos Aires GBGraciela BuldainUniversity of Buenos Aires

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Implication

In vitro spectroscopic analysis reveals an isoporphyrin intermediate during heme oxidation by human heme oxygenase-1, clarifying the mechanism of the initial enzymatic oxygen insertion step.

Key Points

To identify and spectroscopically characterize the proposed transient isoporphyrin intermediate during the initial oxygenation step of heme degradation catalyzed by human heme oxygenase-1.
Reconstituted oxidation reactions of alpha-meso-substituted phenylheme analogs with human heme oxygenase-1 using NADPH-P450 reductase or hydrogen peroxide support.
Tracked and characterized reaction intermediates and decay products using optical absorption spectroscopy, 18O isotopic labeling, reversed-phase HPLC, and LC-ESI mass spectrometry.
Observed a distinct intermediate exhibiting absorption maxima at 435 nm and 930 nm characteristic of an isoporphyrin, displaying half-lives of 1.7 hours for p-trifluoromethylphenyl and 2.4 hours for p-methylphenyl analogs.
Demonstrated that the accumulated isoporphyrin intermediate directly converts to alpha-biliverdin upon addition of NADPH-P450 reductase, incorporating a single oxygen atom from labeled peroxide.

Cite This Study

Evans et al. (2008) studied this question.

synapsesocial.com/papers/6a83882cbffc6f8cb851941a https://doi.org/10.1074/jbc.m709685200

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Implication

In vitro spectroscopic analysis reveals an isoporphyrin intermediate during heme oxidation by human heme oxygenase-1, clarifying the mechanism of the initial enzymatic oxygen insertion step.

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

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Implication

Key Points

Cite This Study

Isoporphyrin Intermediate in Heme Oxygenase Catalysis

Discussion

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Implication

Key Points

Cite This Study

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