- The amino acid substitutions Ser288Gly and Val320Ala convert the cortisol producing enzyme, CYP11B1, into an aldosterone producing enzyme. Curnow, K.M., Mulatero, P., Emeric-Blanchouin, N., Aupetit-Faisant, B., Corvol, P., Pascoe, L. Nat. Struct. Biol. (1997)