Enzymatic synthesis of isoprene from dimethylallyl diphosphate in aspen leaf extracts.

Aspen (Populus tremuloides Michx.) leaf extracts contain a newly discovered enzyme activity that catalyzes the magnesium ion-dependent elimination of diphosphate from dimethylallyl diphosphate with rearrangement to form isoprene (2-methyl, 1-3-butadiene). This isoprene synthase activity has been partially purified. The nonenzymatic reaction of dimethylallyl diphosphate to isoprene, known to be acid catalyzed, may be insignificant at physiological pH. In contrast, the enzymatic reaction may be responsible for the majority of light-dependent isoprene production by isoprene-emitting plants.