Alpha-dioxygenase that catalyzes the primary oxygenation step of a variety of 14-20 carbon fatty acids, containing up to three unsaturated bonds, into their corresponding 2R-hydroperoxides (PubMed:11909851, PubMed:18596034). Involved in the production of oxylipins that function in cell signaling, wound healing, and protection from infection (PubMed:11909851, PubMed:18596034). a 1,2-saturated fatty acid + O2 = a (2R)-2-hydroperoxy fatty acid (9Z,12Z)-octadecadienoate + O2 = (2R,9Z,12Z)-2-hydroperoxyoctadecadienoate hexadecanoate + O2 = (2R)-2-hydroperoxyhexadecanoate (9Z,12Z,15Z)-octadecatrienoate + O2 = (R)-2-hydroperoxy-(9Z,12Z,15Z)-octadecatrienoate O2 + tetradecanoate = (2R)-2-hydroperoxytetradecanoate O2 + octadecanoate = (2R)-2-hydroperoxyoctadecanoate (9Z)-octadecenoate + O2 = (2R,9Z)-2-hydroperoxyoctadecenoate Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit. Binds 1 calcium ion per subunit. Belongs to the peroxidase family.