Arachidonate 12-lipoxygenase, 12S-type (ALOX12) converts arachidonic acid to both hepoxilin A3 (HXA3) and B3 (HXB3). They both incorporate an epoxide across the C-11 and C-12 double bond, as well as an additional hydroxyl moiety with HXA3 having a C-8 hydroxyl, whereas the HXB3 hydroxyl occurs at C-10 (Sutherland et al. 2001, Nigam et al. 2004).
hepoxilin A3 synthase activity of ALOX12:Fe2+ [cytosol]