A Model for the Cobalamin-Dependent Methionine Synthase

Wedemeyer‐Exl, Christina; Darbre, Tamis; Keese, Reinhart

doi:10.1002/(sici)1522-2675(19990804)82:8<1173::aid-hlca1173>3.0.co;2-2

Cited by 21 publications

(17 citation statements)

References 20 publications

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“…Quaternary amines, with a full positive charge on nitrogen, do not require activation, as shown by studies of methyl transfer from a variety of quaternary ammonium salts to Co(I)-cobaloxime [174], trimethylphenylammonium cation to cob(I)alamin [175], and dimethylaniline at low pH to Co(I)-cobyrinate [176]. Furthermore, Lewis acids, such as Zn(II), can catalyze methyl transfer [177]. …”

Section: Description Of the Wood-ljungdahl Pathwaymentioning

confidence: 99%

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Ragsdale

Pierce

2008

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

1,033

816

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I. SummaryConceptually, the simplest way to synthesize an organic molecule is to construct it one carbon at a time. The Wood-Ljungdahl pathway of CO 2 fixation involves this type of stepwise process. The biochemical events that underlie the condensation of two one-carbon units to form the two-carbon compound, acetate, have intrigued chemists, biochemists, and microbiologists for many decades. We begin this review with a description of the biology of acetogenesis. Then, we provide a short history of the important discoveries that have led to the identification of the key components and steps of this usual mechanism of CO and CO 2 fixation. In this historical perspective, we have included reflections that hopefully will sketch the landscape of the controversies, hypotheses, and opinions that led to the key experiments and discoveries. We then describe the properties of the genes and enzymes involved in the pathway and conclude with a section describing some major questions that remain unanswered.

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Section: Description Of the Wood-ljungdahl Pathwaymentioning

confidence: 99%

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Ragsdale

Pierce

2008

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

1,033

816

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“…The methyl group on the CH 3 OCO 2 -bridge in 5 is most possibly derived from a methyl transfer reaction from the N-MeIm solvent. 39,40 Formation of a methyl carbonate bridge in a dinuclear hydroxo-bridged dinickel(II) macrocyclic complex upon reaction with CO 2 in methanol has recently been reported. 41 In the present case, a similar mechanism can give rise to a µ-bicarbonato diiron(III) intermediate which in turn can react with N-MeIm 42 to afford the final methyl carbonate complex 5.…”

Section: Structure Of [Fe 2 (µ-O)(µ-hco 2 )(N-meim) 8 ](Clo 4 ) 3 (4)mentioning

confidence: 99%

Reaction of (μ-Oxo)diiron(III) Core with CO₂ in N-Methylimidazole: Formation of Mono(μ-carboxylato)(μ-oxo)diiron(III) Complexes with N-Methylimidazole as Ligands

2003

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Several iron(III) complexes with N-methylimidazole (N-MeIm) as the ligand have been synthesized by using N-MeIm as the solvent. Under anaerobic conditions, [Fe(N-MeIm)(6)](ClO(4))(3) (1) reacts with stoichiometric amounts of water in N-MeIm to afford the (mu-oxo)diiron(III) complex, [Fe(2)(mu-O)(N-MeIm)(10)](ClO(4))(4) (3). Exposure of a solution of 3 in N-MeIm to stoichiometric and excess CO(2) gives rise to the (mu-oxo)(mu-carboxylato)diiron(III) species [Fe(2)(mu-O)(mu-HCO(2))(N-MeIm)(8)](ClO(4))(3) (4) and the methyl carbonate complex [Fe(2)(mu-O)(mu-CH(3)OCO(2))(N-MeIm)(8)](ClO(4))(3) (5), respectively. Formation of the formato-bridged complex 4 upon fixation of CO(2) by 3 in N-MeIm is unprecedentated. Methyl transfer from N-MeIm to a bicarbonato-bridged (mu-oxo)diiron(III) intermediate appears to give rise to 5. Complex 3 is a good starting material for the synthesis of (mu-oxo)mono(mu-carboxylato)diiron(III) species [Fe(2)(mu-O)(mu-RCO(2))(N-MeIm)(8)](ClO(4))(3) (where R = H (4), CH(3) (6), or C(6)H(5) (7)); addition of the respective carboxylate ligand in stoichiometric amount to a solution of 3 in N-MeIm affords these complexes in high yields. Attempts to add a third bridge to complexes 4, 6, and 7 to form the (mu-oxo)bis(mu-carboxylato)diiron(III) species result in the isolation of the previously known triiron(III) mu-eta(3)-oxo clusters [[Fe(mu-RCO(2))(2)(N-MeIm)](3)O](ClO(4)) (8). The structures of 3, 4, 6, and 7 allow one, for the first time, to inspect the various features of the [Fe(2)(mu-O)(mu-RCO(2))](3+) moiety with no strain from the ligand framework.

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“…These reactions are very interesting from the viewpoint of organic synthesis. Many B 12 artificial enzyme systems are reported as the biomimetic or bioinspired catalysts [9][10][11][12][13][14][15][16][17], but the model reactions of the B 12 -dependent methionine synthase are limited [18][19][20][21][22]. In the present study, we focused on the model reaction of the B 12 -dependent methionine synthase in a non-enzymatic system.…”

Section: Introductionmentioning

confidence: 99%

“…During the catalytic turnover, the cofactor cycles between methylcobalamin and Cob(I)alamin forms, being alternately demethylated by homocysteine and remethylated by CH 3 -H 4 folate. It is difficult to achieve such a catalytic cycle under non-enzymatic conditions, and few model studies with reasonable yields have been reported [19]. During the catalytic turnover, Cob(I)alamin has been shown to be a kinetically competent intermediate.…”

Section: Introductionmentioning

confidence: 99%

Methyl-transfer reaction to alkylthiol catalyzed by a simple vitamin B12 model complex using zinc powder

Pan¹,

Tahara²,

Masuko³

et al. 2011

Inorganica Chimica Acta

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A Model for the Cobalamin-Dependent Methionine Synthase

Cited by 21 publications

References 20 publications

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Reaction of (μ-Oxo)diiron(III) Core with CO₂ in N-Methylimidazole: Formation of Mono(μ-carboxylato)(μ-oxo)diiron(III) Complexes with N-Methylimidazole as Ligands

Methyl-transfer reaction to alkylthiol catalyzed by a simple vitamin B12 model complex using zinc powder

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A Model for the Cobalamin-Dependent Methionine Synthase

Cited by 21 publications

References 20 publications

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Acetogenesis and the Wood–Ljungdahl pathway of CO2 fixation

Reaction of (μ-Oxo)diiron(III) Core with CO2 in N-Methylimidazole: Formation of Mono(μ-carboxylato)(μ-oxo)diiron(III) Complexes with N-Methylimidazole as Ligands

Methyl-transfer reaction to alkylthiol catalyzed by a simple vitamin B12 model complex using zinc powder

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Reaction of (μ-Oxo)diiron(III) Core with CO₂ in N-Methylimidazole: Formation of Mono(μ-carboxylato)(μ-oxo)diiron(III) Complexes with N-Methylimidazole as Ligands