The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Stephen G Sligar - One of the best experts on this subject based on the ideXlab platform.
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Redox Potential control by drug binding to cytochrome p450 3a4
Journal of the American Chemical Society, 2007Co-Authors: Yelena V. Grinkova, Stephen G SligarAbstract:The cytochrome P450s are ubiquitous heme proteins that utilize two reducing equivalents to cleave a ferrous iron - dioxygen complex to produce a single water molecule with the insertion of one oxygen atom into a bound substrate. For the case of soluble cytochrome P450 CYP101, it has been shown that there is a linear free energy relationship between heme Redox Potential and the spin state of the ferric protein. However, the universality of this relationship has been challenged in the case of mammalian enzymes. Most cytochrome P450s are integral membrane proteins, and detailed Redox Potential measurements have proved difficult due protein aggregation or the necessary presence of detergent. In this communication we utilize a soluble nanometer scale membrane bilayer disc (Nanodisc) to stabilize monomeric human cytochrome P450 CYP3A4. The Nanodisc system allows facile Redox Potential measurements to be made on substrate-free CYP3A4 as well as with several drug molecules bound at the active site. We show that substrate binding can dramatically effect the Redox Potential of the heme protein through modulation of the ferric spin state. A linear free energy relationship is observed, analogous to that noted for the soluble P450s, indicating a common mechanism for this linkage and providing a means for control of electron input in response to the presence of a metabolizable substrate, this Potentially limiting the unwanted production of reduced oxygen species.
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Redox Potential control by drug binding to cytochrome P450 3A4
Journal of the American Chemical Society, 2007Co-Authors: Aditi Das, Yelena V. Grinkova, Stephen G SligarAbstract:The cytochrome P450s are ubiquitous heme proteins that utilize two reducing equivalents to cleave a ferrous iron−dioxygen complex to produce a single water molecule with the insertion of one oxygen atom into a bound substrate. For the case of soluble cytochrome P450 CYP101, it has been shown that there is a linear free-energy relationship between heme Redox Potential and the spin state of the ferric protein. However, the universality of this relationship has been challenged in the case of mammalian enzymes. Most cytochrome P450s are integral membrane proteins, and detailed Redox Potential measurements have proved difficult because of protein aggregation or the necessary presence of detergent. In this Communication we utilize a soluble nanometer scale membrane bilayer disc (Nanodisc) to stabilize monomeric human cytochrome P450 CYP3A4. The Nanodisc system allows facile Redox Potential measurements to be made on substrate-free CYP3A4 as well as with several drug molecules bound at the active site. We show t...
Colin Campbell - One of the best experts on this subject based on the ideXlab platform.
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intracellular Redox Potential is correlated with mirna expression in mcf7 cells under hypoxic conditions
Proceedings of the National Academy of Sciences of the United States of America, 2019Co-Authors: Hannah E Johnston, Paul Dickinson, Alasdair Ivens, Amy H Buck, R D Levine, Francoise Remacle, Colin CampbellAbstract:Hypoxia is a ubiquitous feature of cancers, encouraging glycolytic metabolism, proliferation, and resistance to therapy. Nonetheless, hypoxia is a poorly defined term with confounding features described in the literature. Redox biology provides an important link between the external cellular microenvironment and the cell’s response to changing oxygen pressures. In this paper, we demonstrate a correlation between intracellular Redox Potential (measured using optical nanosensors) and the concentrations of microRNAs (miRNAs) involved in the cell’s response to changes in oxygen pressure. The correlations were established using surprisal analysis (an approach derived from thermodynamics and information theory). We found that measured Redox Potential changes reflect changes in the free energy computed by surprisal analysis of miRNAs. Furthermore, surprisal analysis identified groups of miRNAs, functionally related to changes in proliferation and metastatic Potential that played the most significant role in the cell’s response to changing oxygen pressure.
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Simultaneous intracellular Redox Potential and pH measurements in live cells using SERS nanosensors
Analyst, 2015Co-Authors: Lauren E. Jamieson, Aleksandra Jaworska, Jing Jiang, Malgorzata Baranska, David J. Harrison, Colin CampbellAbstract:Intracellular Redox Potential is a highly regulated cellular characteristic and is critically involved in maintaining cellular health and function. The dysregulation of Redox Potential can result in the initiation and progression of numerous diseases. Redox Potential is determined by the balance of oxidants and reductants in the cell and also by pH. For this reason a technique for quantitative measurement of intracellular Redox Potential and pH is highly desirable. In this paper we demonstrate how surface enhanced Raman scattering (SERS) nanosensors can be used for multiplexed measurement of both pH and Redox Potential in live single cells.
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monitoring intracellular Redox Potential changes using sers nanosensors
ACS Nano, 2012Co-Authors: Craig Auchinvole, Patricia Richardson, Catherine Mcguinnes, Venkatesh Mallikarjun, Ken Donaldson, Hamish Mcnab, Colin CampbellAbstract:Redox homeostasis and signaling are critically important in the regulation of cell function. There are significant challenges in quantitatively measuring intracellular Redox Potentials, and in this paper, we introduce a new approach. Our approach is based on the use of nanosensors which comprise molecules that sense the local Redox Potential, assembled on a gold nanoshell. Since the Raman spectrum of the sensor molecule changes depending on its oxidation state and since the nanoshell allows a huge enhancement of the Raman spectrum, intracellular Potential can be calculated by a simple optical measurement. The nanosensors can be controllably delivered to the cytoplasm, without any toxic effects, allowing Redox Potential to be monitored in a reversible, non-invasive manner over a previously unattainable Potential range encompassing both superphysiological and physiological oxidative stress.
Leopold Flohe - One of the best experts on this subject based on the ideXlab platform.
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the fairytale of the gssg gsh Redox Potential
Biochimica et Biophysica Acta, 2013Co-Authors: Leopold FloheAbstract:Abstract Background The term GSSG/GSH Redox Potential is frequently used to explain Redox regulation and other biological processes. Scope of review The relevance of the GSSG/GSH Redox Potential as driving force of biological processes is critically discussed. It is recalled that the concentration ratio of GSSG and GSH reflects little else than a steady state, which overwhelmingly results from fast enzymatic processes utilizing, degrading or regenerating GSH. Major conclusions A biological GSSG/GSH Redox Potential, as calculated by the Nernst equation, is a deduced electrochemical parameter based on direct measurements of GSH and GSSG that are often complicated by poorly substantiated assumptions. It is considered irrelevant to the steering of any biological process. GSH-utilizing enzymes depend on the concentration of GSH, not on [GSH] 2 , as is predicted by the Nernst equation, and are typically not affected by GSSG. Regulatory processes involving oxidants and GSH are considered to make use of mechanistic principles known for thiol peroxidases which catalyze the oxidation of hydroperoxides by GSH by means of an enzyme substitution mechanism involving only bimolecular reaction steps. General significance The negligibly small rate constants of related spontaneous reactions as compared with enzyme-catalyzed ones underscore the superiority of kinetic parameters over electrochemical or thermodynamic ones for an in-depth understanding of GSH-dependent biological phenomena. At best, the GSSG/GSH Potential might be useful as an analytical tool to disclose disturbances in Redox metabolism. This article is part of a Special Issue entitled Cellular Functions of Glutathione.
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The fairytale of the GSSG/GSH Redox Potential
Biochimica et Biophysica Acta, 2012Co-Authors: Leopold FloheAbstract:Abstract Background The term GSSG/GSH Redox Potential is frequently used to explain Redox regulation and other biological processes. Scope of review The relevance of the GSSG/GSH Redox Potential as driving force of biological processes is critically discussed. It is recalled that the concentration ratio of GSSG and GSH reflects little else than a steady state, which overwhelmingly results from fast enzymatic processes utilizing, degrading or regenerating GSH. Major conclusions A biological GSSG/GSH Redox Potential, as calculated by the Nernst equation, is a deduced electrochemical parameter based on direct measurements of GSH and GSSG that are often complicated by poorly substantiated assumptions. It is considered irrelevant to the steering of any biological process. GSH-utilizing enzymes depend on the concentration of GSH, not on [GSH] 2 , as is predicted by the Nernst equation, and are typically not affected by GSSG. Regulatory processes involving oxidants and GSH are considered to make use of mechanistic principles known for thiol peroxidases which catalyze the oxidation of hydroperoxides by GSH by means of an enzyme substitution mechanism involving only bimolecular reaction steps. General significance The negligibly small rate constants of related spontaneous reactions as compared with enzyme-catalyzed ones underscore the superiority of kinetic parameters over electrochemical or thermodynamic ones for an in-depth understanding of GSH-dependent biological phenomena. At best, the GSSG/GSH Potential might be useful as an analytical tool to disclose disturbances in Redox metabolism. This article is part of a Special Issue entitled Cellular Functions of Glutathione.
Yelena V. Grinkova - One of the best experts on this subject based on the ideXlab platform.
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Redox Potential control by drug binding to cytochrome p450 3a4
Journal of the American Chemical Society, 2007Co-Authors: Yelena V. Grinkova, Stephen G SligarAbstract:The cytochrome P450s are ubiquitous heme proteins that utilize two reducing equivalents to cleave a ferrous iron - dioxygen complex to produce a single water molecule with the insertion of one oxygen atom into a bound substrate. For the case of soluble cytochrome P450 CYP101, it has been shown that there is a linear free energy relationship between heme Redox Potential and the spin state of the ferric protein. However, the universality of this relationship has been challenged in the case of mammalian enzymes. Most cytochrome P450s are integral membrane proteins, and detailed Redox Potential measurements have proved difficult due protein aggregation or the necessary presence of detergent. In this communication we utilize a soluble nanometer scale membrane bilayer disc (Nanodisc) to stabilize monomeric human cytochrome P450 CYP3A4. The Nanodisc system allows facile Redox Potential measurements to be made on substrate-free CYP3A4 as well as with several drug molecules bound at the active site. We show that substrate binding can dramatically effect the Redox Potential of the heme protein through modulation of the ferric spin state. A linear free energy relationship is observed, analogous to that noted for the soluble P450s, indicating a common mechanism for this linkage and providing a means for control of electron input in response to the presence of a metabolizable substrate, this Potentially limiting the unwanted production of reduced oxygen species.
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Redox Potential control by drug binding to cytochrome P450 3A4
Journal of the American Chemical Society, 2007Co-Authors: Aditi Das, Yelena V. Grinkova, Stephen G SligarAbstract:The cytochrome P450s are ubiquitous heme proteins that utilize two reducing equivalents to cleave a ferrous iron−dioxygen complex to produce a single water molecule with the insertion of one oxygen atom into a bound substrate. For the case of soluble cytochrome P450 CYP101, it has been shown that there is a linear free-energy relationship between heme Redox Potential and the spin state of the ferric protein. However, the universality of this relationship has been challenged in the case of mammalian enzymes. Most cytochrome P450s are integral membrane proteins, and detailed Redox Potential measurements have proved difficult because of protein aggregation or the necessary presence of detergent. In this Communication we utilize a soluble nanometer scale membrane bilayer disc (Nanodisc) to stabilize monomeric human cytochrome P450 CYP3A4. The Nanodisc system allows facile Redox Potential measurements to be made on substrate-free CYP3A4 as well as with several drug molecules bound at the active site. We show t...
Aditi Das - One of the best experts on this subject based on the ideXlab platform.
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Redox Potential control by drug binding to cytochrome P450 3A4
Journal of the American Chemical Society, 2007Co-Authors: Aditi Das, Yelena V. Grinkova, Stephen G SligarAbstract:The cytochrome P450s are ubiquitous heme proteins that utilize two reducing equivalents to cleave a ferrous iron−dioxygen complex to produce a single water molecule with the insertion of one oxygen atom into a bound substrate. For the case of soluble cytochrome P450 CYP101, it has been shown that there is a linear free-energy relationship between heme Redox Potential and the spin state of the ferric protein. However, the universality of this relationship has been challenged in the case of mammalian enzymes. Most cytochrome P450s are integral membrane proteins, and detailed Redox Potential measurements have proved difficult because of protein aggregation or the necessary presence of detergent. In this Communication we utilize a soluble nanometer scale membrane bilayer disc (Nanodisc) to stabilize monomeric human cytochrome P450 CYP3A4. The Nanodisc system allows facile Redox Potential measurements to be made on substrate-free CYP3A4 as well as with several drug molecules bound at the active site. We show t...
