FIGURE 8.

Three potential mechanisms explaining the appearance of oxygen from water in the 13-hydroxyl of the linoleic acid-derived epoxyalcohol. A, exchange of the ferryl heme oxygen with water prior to oxygen rebound. B, formation of the 13-hydroxyl via two routes, direct oxygen rebound of the ferryl oxygen, and reaction of water with a carbocation intermediate. C, water reacts with a carbocation intermediate, and the water derives partly from release of the ferryl oxygen, and partially from H₂O in the enzyme active site.