 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase

In enzymology, a 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase (HMB-PP synthase, IspG, ) is an enzyme that catalyzes the chemical reaction

The substrate of this enzyme is 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP) and the product is (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMB-PP).Electrons are donated by two reduced ferredoxin proteins per reaction.