ID 2.5.1.82 DE Hexaprenyl diphosphate synthase (geranylgeranyl-diphosphate specific). AN (All-trans)-hexaprenyl-diphosphate synthase. CA Geranylgeranyl diphosphate + 2 isopentenyl diphosphate = 2 diphosphate + CA all-trans-hexaprenyl diphosphate. CF Mg(2+). CC -!- The enzyme prefers geranylgeranyl diphosphate to farnesyl diphosphate CC as an allylic substrate and does not show activity for geranyl CC diphosphate and prenyl diphosphate. CC -!- Formerly EC 2.5.1.33. DR Q97W92, HEXPP_SACS2; //