Catalytic Mechanism of Escherichia coli Isopentenyl Diphosphate Isomerase Involves Cys-67, Glu-116, and Tyr-104 as Suggested by Crystal Structures of Complexes with Transition State Analogues and Irreversible Inhibitors
Wouters, J., Oudjama, Y., Barkley, S.J., Tricot, C., Stalon, V., Droogmans, L., Poulter, C.D.(2003) J Biol Chem 278: 11903-11908
- PubMed: 12540835 
- DOI: https://doi.org/10.1074/jbc.M212823200
- Primary Citation of Related Structures:  
1NFS, 1NFZ - PubMed Abstract: 
Isopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase is a key enzyme in the biosynthesis of isoprenoids. The reaction involves protonation and deprotonation of the isoprenoid unit and proceeds through a carbocationic transition state. Analysis of the crystal structures (2 A) of complexes of Escherichia coli IPP.DMAPPs isomerase with a transition state analogue (N,N-dimethyl-2-amino-1-ethyl diphosphate) and a covalently attached irreversible inhibitor (3,4-epoxy-3-methyl-1-butyl diphosphate) indicates that Glu-116, Tyr-104, and Cys-67 are involved in the antarafacial addition/elimination of protons during isomerization. This work provides a new perspective about the mechanism of the reaction.
Organizational Affiliation: 
Institut de Recherches Microbiologiques J.M. Wiame, 1 av E. Gryzon 1070 Bruxelles, Belgium. [email protected]