The Formation of Free Radicals in Human Granulocytes and Cerebellar Granule Cells
Frode Fonnum, Oddvar Myhre, Øyvind A. Voie, Jannike M. Andersen and Anne Dreiem
The formation of free radicals plays an important part in cell death. A free radical is defined as any species capable of independent existence that contains one or more unpaired electrons. An unpaired electron is one that occupies an atomic or molecular orbital by itself. The presence of one or more unpaired electrons makes such species highly reactive, although the reactivity varies over a large scale. In the following discussions, the hydroxyl radical, superoxide radical and hydroperoxyl radical are considered to be important radicals. Other reactive compounds, the so-called reactive oxygen species (ROS) or reactive nitrogen species (RNS), which have similar important functions, include hydrogen peroxide, hypochlorous acid and peroxynitrite. Free radicals, ROS and RNS can cause cell damage by their reaction with DNA, proteins and lipids.