(5Z,8Z,11Z,14Z,17Z)-eicosapentaenoate + reduced [NADPH--hemoprotein reductase] + O2 <=> (17S,18R)-epoxy-(5Z,8Z,11Z,14Z)-eicosatetraenoate + oxidized [NADPH--hemoprotein reductase] + H2O + H(+)
(5z,8z,11z,14z,17z)-eicosapentaenoate + reduced [nadph--hemoprotein reductase] + o2 <=> (17s,18r)-epoxy-(5z,8z,11z,14z)-eicosatetraenoate + oxidized [nadph--hemoprotein reductase] + h2o + h(+)