The synthesis of (S)-beta-macrocarpene from (2E,6E)-farnesyl diphosphate proceeds in two steps. The first step is the cyclization to (S)-beta-bisabolene. The second step is the isomerization to (S)-beta-macrocarpene (cf. EC 5.5.1.17, (S)-beta-macrocarpene synthase). The enzyme requires Mg2+ or Mn2+ for activity.