Structure of SLO and its active site. The two domains are color coded: wheat, N-terminal domain only present in human and plants, and light blue, C-terminal catalytic domain. The reactive portion of the substrate linoleic acid, pale green, has been modeled into the high resolution X-ray structure of SLO (3PZW; 1.4Å); the reactive carbon, C11, is colored black. The side chains discussed in the text are shown as pale yellow sticks. The ferric hydroxide cofactor is displayed as orange and red spheres, respectively. Side chains that ligate the catalytic cofactor are also shown.