Figure 4
1H-NMR spectra of reaction products obtained by incubating IPP substrate with (a) and without (b) purified EuIPI protein in enzymatic activity assay. Red arrows indicate four signals characteristic of DMAPP (1.53, 1.58, 4.3, 5.3 ppm), which was produced from IPP catalyzed by EuIPI, and were absent from the reaction without EuIPI. Signals of IPP substrate (1.59, 2.3, 3.9, 4.7 ppm; blue arrows) were detected in the reaction either with or without purified EuIPI protein. These results indicated that the cDNA clone isolated from E. ulmoides encoded a functional IPP isomerase capable of catalyzing the conversion of IPP to DMAPP in vitro.