Harnessing enzyme plasticity for the synthesis of oxygenated sesquiterpenoids.

8-Methoxy-γ-humulene, (E)-8-methoxy-β-farnesene, 12-methoxy-β-sesquiphellandrene and 12-methoxyzingiberene can be synthesised in amorphadiene synthase-catalysed reactions from 8- and 12-methoxyfarnesyl diphosphates due to the highly plastic yet tightly controlled carbocationic chemistry of this sesquiterpene cyclase.