Reaction catalyzed by DELTA7-sterol 5(6)-desaturase (1.14.19.20)
+
2
+
+
2
=
+
2
+
2
H2O
5alpha-cholest-7-en-3beta-ol
+
2 ferrocytochrome b5
+
O2
+
2 H+
=
cholesta-5,7-dien-3beta-ol
+
2 ferricytochrome b5
+
2 H2O
