The unique structural aspect of peroxygenases is the interaction of the carboxylate group of the fatty acids with an Arginine residue close to the heme site. This feature bypasses the necessity of acid-alcohol pair for proton deliveries as in common P450s. These special features of P450 peroxygenases indicate that this group of enzymes might have been bioengineered by Nature during primeval conditions which necessitate bypassing dioxygen requirement for the catalytic cycle. Despite these differences, peroxygenases catalyze fatty acid oxidation, by use of the same active oxidant, Cpd I, as in common P450s. In the past, we have shown how the H2O2 shunting generates Cpd I species in P450SPα and P450BSβ, which perform C-H hydroxylations of fatty acids. So what is so special about peroxygenases? The discovery of P450OleT, The key difference, between these enzymes is a single residue adjacent to the heme; it is glutamine (Q85) in P450SPα and P450BSβ, whereas in P450OleT (cf. Fig 1) this residue is Histidine (H85).