Antioxidants and redox regulation: Changing notions in a changing world

The concepts of antioxidants and redox regulation are reconsidered in the light of recent findings, and some new future challenges for redox biology are outlined. It is suggested that antioxidants, thioredoxin-mediated redox regulation, and signal transduction mediated by reactive oxygen and nitrogen species, are all part of the same broad mechanism. The integration of different redox inputs, by affecting reversible thiol-disulfide dynamics in a set of target proteins, could result in the regulation of key processes such as proteolysis, gene expression and the functioning of selected metabolic pathways. Most interestingly, redox regulation is not just based on a binary “yes or no” response, and is therefore a convenient way to achieve graded control over the continuum of environmental variables.