Redox regulation of protein tyrosine phosphatase activity by hydroxyl radical

► ROS are implicated as mediators of cell-signaling responses by targeting the PTPs. ► The exact identity of the oxidants that inactivate the PTPs is unknown. ► We show that the hydroxyl radical is capable of inactivating the PTPs. ► We also show that hydroxyl radical is a kinetically more efficient oxidant than H2O2. ► Hydroxyl radical is a more physiologically relevant oxidant for PTP inactivation.