Delta 4 desaturase (20:5(5Z,8Z,11Z,14Z,17Z)/22:6(4Z,7Z,10Z,13Z,16Z,19Z))(PC sn-2)
2.0 nadh_c + o2_c + 2.0 ficytb5_c + pc205n3225n3_c ⇌ 2.0 h2o_c + 2.0 nad_c + 2.0 focytb5_c + pc205n3226n3_c