Direct relationship between dimeric form and activity in the acidic copper-zinc superoxide dismutase from lemon.

The copper-zinc superoxide dismutase (CuZnSOD) from lemon (SOD_CL) is active in an acidic environment and resists proteolytic degradation. The enzyme occurs as a dimer, which has an indirect effect on the enzyme activity as the monomer retains only ∼35% of the activity. Here, the crystal structure of SOD_CL at 1.