21-hydroxyprogesterone + 2 reduced [adrenodoxin] + O2 + 2 H(+) = 18-hydroxy-11-deoxycorticosterone + 2 oxidized [adrenodoxin] + H2O
21-hydroxyprogesterone + 2 reduced [adrenodoxin] + o2 + 2 h(+) = 18-hydroxy-11-deoxycorticosterone + 2 oxidized [adrenodoxin] + h2o