Allene oxide synthase converts a fatty acid hydroperoxide to an allene oxide, which is an unstable epoxide. In corals, the enzyme is part of a eiconaosid synthesis pathway that is initiated by a lipoxygenase, which generates the fatty acid hydroperoxides in the first step. The structure of allene oxide synthase closely resembles that of catalase, but allene oxide synthase does not have catalase activity.