Dioxygen Activation at Mononuclear Nonheme Iron Active Sites:  Enzymes, Models, and Intermediates

Abstract

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Transition States in a Protein Environment − ONIOM QM:MM Modeling of Isopenicillin N Synthesis

“…16 Isopenicillin N synthase is a member of a family of mononuclear non-heme iron enzymes with a 2-His-1-carboxylate iron-binding motif. [17][18][19] It uses the four-electron oxidative power of 21 ferrous iron, which gives a ferric superoxo species 22 that activates the cysteine β-C-H bond leading to formation of an iron-bound peroxide. 23 According to the proposal in reference 20, the peroxide abstracts the valine N-H proton to generate the ferryl-oxo and a water molecule.…”

Facial triad modelling using ferrous pyridinyl prolinate complexes: synthesis and catalytic applications

“…After the solution reached ambient temperature it was stirred for an additional 60 min at 60°C after which the reaction was quenched with n PrOH (2.0 mL), stirred for 15 min, evaporated, and dried in vacuo to leave a white powder, which was used in the subsequent reaction without further purification (2.04 g, quant. (S)-Methyl-1-((6-methylpyridin-2-yl)methyl)pyrrolidine-2-carboxylate (6-Me-PyProMe) (2). A yellow suspension of 2-(chloromethyl)-6-methylpyridinium chloride (9.62 g, 54.0 mmol), (S)-2-(methoxycarbonyl)pyrrolidinium chloride (12.2 g, 73.5 mmol), NaI (3.08 g, 20.5 mmol) and Na 2 CO 3 (19.0 g, 179 mmol) in anhydrous DMF (140 mL) was stirred at 50°C.…”

“…In the IR-spectra of complex 11 a broad peak is observed for the OH group around 3339 cm −1 . The peak of the OH group in the free ligand is found at a higher wavenumber (3395 cm −1 2 (10) by slow vapour diffusion of diethyl ether into an acetonitrile solution of the complex. Crystal structure determination showed a very distorted octahedral geometry for the iron complex (Fig.…”

“…Efforts towards modelling of the active sites of such enzymes have, therefore, not only focused on a further understanding of the enzyme activity and on studying (electronic) structure-activity relationships, but have also focused on the design of bio-inspired oxidation catalysts. 2 Amongst these enzymes, the binuclear enzyme sMMO has attracted a lot of attention over the years because of its property to selectively oxidize methane to methanol. 3 More recently, a class of mono-nuclear non-heme iron enzymes that possess a so-called 2-His-1-carboxylate facial triad active site have gained widespread interest ( Fig.…”

“…2A). This ligand family combines a carboxylate donor moiety with two biologically relevant imidazole donor moieties in a predisposed facial manner and enables the synthesis of discrete [M(BAIP) 2 ] and [M(BAIP)(X) 2 L] complexes, where M = Fe, Cu, Zn, (X) 2 are two anionic ligands or is a bidentate mono-or dianionic ligand, and L is a neutral donor ligand like H 2 O or pyridine. 15 Substitution of the imidazole moieties in the BAIP-ligands allows for the variation of their steric and site isolating, as well as their solubility properties.…”