title: Redox environment of the cell as viewed through the redox state of the glutathione disulfide/glutathione couple.
abstract: Redox state is a term used widely in the research field of free radicals and oxidative stress. Unfortunately, it is used as a general term referring to relative changes that are not well defined or quantitated. In this review we provide a definition for the redox environment of biological fluids, cell organelles, cells, or tissue. We illustrate how the reduction potential of various redox couples can be estimated with the Nernst equation and show how pH and the concentrations of the species comprising different redox couples influence the reduction potential. We discuss how the redox state of the glutathione disulfide-glutathione couple (GSSG/2GSH) can serve as an important indicator of redox environment. There are many redox couples in a cell that work together to maintain the redox environment; the GSSG/2GSH couple is the most abundant redox couple in a cell. Changes of the half-cell reduction potential (E(hc)) of the GSSG/2GSH couple appear to correlate with the biological status of the cell: proliferation E(hc) approximately -240 mV; differentiation E(hc) approximately -200 mV; or apoptosis E(hc) approximately -170 mV. These estimates can be used to more fully understand the redox biochemistry that results from oxidative stress. These are the first steps toward a new quantitative biology, which hopefully will provide a rationale and understanding of the cellular mechanisms associated with cell growth and development, signaling, and reductive or oxidative stress.
authors.affiliation: Free Radical Research Institute & ESR Facility, The University of Iowa, Iowa City, IA 52242-1101, USA. fraya-schafer@uiowa.edu
authors.forename: F Q
authors.initials: FQ
authors.lastname: Schafer
authors.forename: G R
authors.initials: GR
authors.lastname: Buettner
mesh_terms: D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology*; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D015398:Signal Transduction / Q000502:physiology; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D013438:Sulfhydryl Compounds; D005978:Glutathione; D019803:Glutathione Disulfide