Possible antioxidant action of the Bcl-2 protein

Reactive oxygen species (ROS) have been implicated as mediators of programmed cell death (PCD). PCD is involved in many physiological and pathological processes. The Bcl-2 protein suppresses various types of apoptotic and in some cases necrotic cell death. The Bcl-2 protein is located at sites of free radical generation such as mitochondria and endoplasmic reticulum. However, it's mechanism of action is unknown. It has been suggested the Bcl-2 protein may act via an antioxidant mechanism to prevent PCD. To determine whether the Bcl-2 protein itself has antioxidant properties we tested the purified protein directly in our assay systems. We compared the action of the Bcl-2 protein with that of well known antioxidant proteins: catalase, glutathione peroxidase and Superoxide dismutase. We conclude that, in our assay systems, Bcl-2 appears not to show any significant 02'", H2U2 or organic peroxide-removing activity when compared with the above proteins.