Reactive oxygen species (ROS) produced by the mitochondrial respiratory chain can be a
redox signal, but whether they affect mitochondrial function is unclear. Here we show that
low levels of ROS from the respiratory chain under physiological conditions reversibly
modify the thiol redox state of mitochondrial proteins involved in fatty acid and carbohydrate
metabolism. As these thiol modifications were specific and occurred without bulk thiol
changes, we first had to develop a sensitive technique to identify the small number of …