2dho
Crystal structure of human IPP isomerase I in space group P212121
Structural highlights
FunctionIDI1_HUMAN Catalyzes the 1,3-allylic rearrangement of the homoallylic substrate isopentenyl (IPP) to its highly electrophilic allylic isomer, dimethylallyl diphosphate (DMAPP).[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedType I isopentenyl diphosphate (IPP): dimethylally diphosphate (DMAPP) isomerase is an essential enzyme in human isoprenoid biosynthetic pathway. It catalyzes isomerization of the carbon-carbon double bonds in IPP and DMAPP, which are the basic building blocks for the subsequent biosynthesis. We have determined two crystal structures of human IPP isomerase I (hIPPI) under different crystallization conditions. High similarity between structures of human and Escherichia coli IPP isomerases proves the conserved catalytic mechanism. Unexpectedly, one of the hIPPI structures contains a natural substrate analog ethanol amine pyrophosphate (EAPP). Based on this structure, a water molecule is proposed to be the direct proton donor for IPP and different conformations of IPP and DMAPP bound in the enzyme are also proposed. In addition, structures of human IPPI show a flexible N-terminal alpha-helix covering the active pocket and blocking the entrance, which is absent in E. coli IPPI. Besides, the active site conformation is not the same in the two hIPPI structures. Such difference leads to a hypothesis that substrate binding induces conformational change in the active site. The inhibition mechanism of high Mn(2+) concentrations is also discussed. Crystal structures of human IPP isomerase: new insights into the catalytic mechanism.,Zhang C, Liu L, Xu H, Wei Z, Wang Y, Lin Y, Gong W J Mol Biol. 2007 Mar 9;366(5):1437-46. Epub 2006 Nov 3. PMID:17137593[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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