FIGURE 2.

Divalent cation dependence of MBO synthase activity. MBO synthase was extracted in sodium phosphate buffer free of divalent cations. Divalent cation-free enzyme was then assayed in a reaction mixture containing final concentrations of 100 mm Hepes (pH 8.0), 100 mm KCl, 11.2 mm DMADP, and 20 mm DTT. Other details are as described in the legend to Fig. 1. Data were normalized to the amount of MBO produced at 20 mm MgCl₂ for each trial. ●, isoprene; ○, MBO. Black bars, data for MBO; gray bars, data for isoprene.