Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species.
The bi-enzymatic system of cytochrome P450 (CYP, a hemoprotein) and cytochrome P450 reductase (CPR, a diflavoenzyme) mediate the redox metabolism of diverse indigenous and xenobiotic molecules in various cellular and organ systems, using oxygen and NADPH. Curiously, when a 1:1 ratio is seen to be op...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2010-01-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC2954143?pdf=render |
| _version_ | 1818516731013890048 |
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| author | Kelath Murali Manoj Sudeep Kumar Gade Lazar Mathew |
| author_facet | Kelath Murali Manoj Sudeep Kumar Gade Lazar Mathew |
| author_sort | Kelath Murali Manoj |
| collection | DOAJ |
| description | The bi-enzymatic system of cytochrome P450 (CYP, a hemoprotein) and cytochrome P450 reductase (CPR, a diflavoenzyme) mediate the redox metabolism of diverse indigenous and xenobiotic molecules in various cellular and organ systems, using oxygen and NADPH. Curiously, when a 1:1 ratio is seen to be optimal for metabolism, the ubiquitous CYP:CPR distribution ratio is 10 to 100:1 or higher. Further, the NADPH equivalents consumed in these in vitro or in situ assemblies usually far exceeded the amount of substrate metabolized. We aimed to find the rationale to explain for these two oddities. We report here that CPR is capable of activating molecular oxygen on its own merit, generating diffusible reduced oxygen species (DROS). Also, in the first instance for a flavoprotein, CPR is shown to deplete peroxide via diffusible radical mediated process, thereby leading to the formation of water (but without significant evolution of oxygen). We also quantitatively demonstrate that the rate of oxygen activation and peroxide depletion by CPR accounts for the major reactivity in the CYP+CPR mixture. We show unambiguously that CPR is able to regulate the concentration of diffusible reduced oxygen species in the reaction milieu. These findings point out that CPR mediated processes are bound to be energetically 'wasteful' and potentially 'hazardous' owing to the unavoidable nature of the CPR to generate and deplete DROS. Hence, we can understand that CPR is distributed at low densities in cells. Some of the activities that were primarily attributed to the heme-center of CYP are now established to be a facet of the flavins of CPR. The current approach of modeling drugs to minimize "uncoupling" on the basis of erstwhile hypothesis stands questionable, considering the ideas brought forth in this work. |
| first_indexed | 2024-12-11T00:46:07Z |
| format | Article |
| id | doaj.art-cf877ac238434acaa4f362331d6528b5 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-11T00:46:07Z |
| publishDate | 2010-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-cf877ac238434acaa4f362331d6528b52022-12-22T01:26:47ZengPublic Library of Science (PLoS)PLoS ONE1932-62032010-01-01510e1327210.1371/journal.pone.0013272Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species.Kelath Murali ManojSudeep Kumar GadeLazar MathewThe bi-enzymatic system of cytochrome P450 (CYP, a hemoprotein) and cytochrome P450 reductase (CPR, a diflavoenzyme) mediate the redox metabolism of diverse indigenous and xenobiotic molecules in various cellular and organ systems, using oxygen and NADPH. Curiously, when a 1:1 ratio is seen to be optimal for metabolism, the ubiquitous CYP:CPR distribution ratio is 10 to 100:1 or higher. Further, the NADPH equivalents consumed in these in vitro or in situ assemblies usually far exceeded the amount of substrate metabolized. We aimed to find the rationale to explain for these two oddities. We report here that CPR is capable of activating molecular oxygen on its own merit, generating diffusible reduced oxygen species (DROS). Also, in the first instance for a flavoprotein, CPR is shown to deplete peroxide via diffusible radical mediated process, thereby leading to the formation of water (but without significant evolution of oxygen). We also quantitatively demonstrate that the rate of oxygen activation and peroxide depletion by CPR accounts for the major reactivity in the CYP+CPR mixture. We show unambiguously that CPR is able to regulate the concentration of diffusible reduced oxygen species in the reaction milieu. These findings point out that CPR mediated processes are bound to be energetically 'wasteful' and potentially 'hazardous' owing to the unavoidable nature of the CPR to generate and deplete DROS. Hence, we can understand that CPR is distributed at low densities in cells. Some of the activities that were primarily attributed to the heme-center of CYP are now established to be a facet of the flavins of CPR. The current approach of modeling drugs to minimize "uncoupling" on the basis of erstwhile hypothesis stands questionable, considering the ideas brought forth in this work.http://europepmc.org/articles/PMC2954143?pdf=render |
| spellingShingle | Kelath Murali Manoj Sudeep Kumar Gade Lazar Mathew Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. PLoS ONE |
| title | Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. |
| title_full | Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. |
| title_fullStr | Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. |
| title_full_unstemmed | Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. |
| title_short | Cytochrome P450 reductase: a harbinger of diffusible reduced oxygen species. |
| title_sort | cytochrome p450 reductase a harbinger of diffusible reduced oxygen species |
| url | http://europepmc.org/articles/PMC2954143?pdf=render |
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