InterPro domain: IPR011876

This entry represents type 1 of two non-homologous families of the enzyme isopentenyl-diphosphate delta-isomerase (IPP isomerase; 5.3.3.2 ). IPP isomerase is a member of the Nudix hydrolase superfamily, and is a key enzyme in the isoprenoid biosynthetic pathway. It catalyses the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate. Dimethylallyl phosphate is the initial substrate for the biosynthesis of carotenoids and other long chain isoprenoids [ 1 ]. IPP is an essential building block for many compounds, including enzyme cofactors, sterols, and prenyl groups. This enzyme interconverts isopentenyl diphosphate and dimethylallyl diphosphate. The enzyme requires one Mn2+ or Mg2+ ion in its active site to fold into an active conformation and also contains the Nudix motif, a highly conserved 23-residue block (GX5EX7REUXEEXGU, where U = I, L or V), that functions as a metal binding and catalytic site. The metal binding site is present within the active site and plays structural and catalytical roles. IPP isomerase is well represented in several bacteria, archaebacteria and eukaryotes, including fungi, mammals and plants. Despite sequence variations (mainly at the N terminus), the core structure is highly conserved [ 2 ].

1. Differential expression of two isopentenyl pyrophosphate isomerases and enhanced carotenoid accumulation in a unicellular chlorophyte. Proc. Natl. Acad. Sci. U.S.A. 95, 11482-8
2. Isopentenyl diphosphate isomerase: a core enzyme in isoprenoid biosynthesis. A review of its biochemistry and function. Nat Prod Rep 14, 591-603