An open reading frame (Acc. no. P50740) on theBacillus subtilis chromosome extending from bp 184 997–186 043 with similarity to theidi-2 gene ofStreptomycessp. CL190 specifying type II isopentenyl diphosphate isomerase was expressed in a recombinant Escherichia colistrain. The recombinant protein with a subunit mass of 39 kDa was purified to apparent homogeneity by column chromatog-raphy. The protein was shown to catalyse the conversion of dimethylallyl diphosphate into isopentenyl diphosphate and vice versa at rates of and )1 Æmin )1 , respectively, as diagnosed by 1 H spectroscopy. .
