Though the two-water channels are rather similar in both peroxygenases, we found a significant difference in the behaviors of the substrates. In P450OleT (cf. Fig. ), the substrate (abbreviated as DCR) interacts with His85 via a bridging water W1, which causes the substrate to recline towards the His85. The first oxygen O1 of the carboxylate group in P450OleT forms a bidentate interaction with the guanidine groups of the Arginine residue (R245), while the second oxygen, O2, interacts with the two water molecules W1 and W2 (cf. Fig. ). Interestingly, an equivalent interaction between the substrate (PAM) and Gln 85 in P450BSβ is completely absent.