The acireductone dioxygenase (ARD) metalloenzymes regulate the formation of the polyamine biosynthesis inhibitor methylthioadenosine through the methionine salvage pathway, a crucial biosynthetic pathway in plants and prokaryotes. The ARD protein will incorporate either nickel or iron depending on bioavailability. The Fe-ARD and Ni-ARD demonstrate a unique structure-function relationship dependent solely on the metal bound. Both metal congeners share identical amino acid residues yet when Fe 2+ is incorporated into the metal center the catalytic activity change is significant enough to cause an off-pathway shunt. Dr. Santiago Toledo of Texas Lutheran University has developed a family of biomimetic models of the ARD metalloenzymes, [NiII(OMe2(6-H-DPPN))] and [ZnII(OPh(6-H-DPPN))] that approximates the nickel and zinc coordination at the active site through a polydentate ligand. Geometry optimizations of the zinc complex through Density Functional (DFT) computational methods show high structural similarity to crystallographic results. Further computational analysis will be used to provide insight into the nature of the unique metal dependence of this system.

Biomimetic modeling of Ni-ARD's active site with zinc and nickel metal complexes

247th National Meeting (2014)

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