Fig. 3

Optimization of the in vitro synthetic unit and the effects of enzyme levels on isoprene production. a Determination of the optimal enzyme level of each enzyme within synthetic unit, when four other enzymes were kept at constant level of 0.5 µM. b Production of isoprene using balanced or unbalanced synthetic unit. c Effects of increased synthetic units towards the isoprene production. Each unbalanced synthetic unit has 0.5 µM of MVK, PMK, MVD, IDI and ISPS. Each balanced synthetic unit has 0.5 µM of MVK, PMK, MVD; 1.0 µM of IDI, 8.0 µM of ISPS (MVK:PMK:MVD:IDI:Isps = 1:1:1:2:12). a, b and c followed the below conditions: 50 mM phosphate buffer, 30 mM potassium chloride, 10 mM magnesium chloride, and 4 mM β-mercaptoethanol, 10 mM ATP and 2.5 mM mevalonic acid. The data shown are means of three repeated experiments and the error bars present the standard deviation