Acetate synthesis from carbon monoxide by Clostridium thermoaceticum. Purification of the corrinoid protein.

Hu, Schweikert; Pezacka, E.; Wood, Harland G.

doi:10.1016/s0021-9258(17)47238-3

Cited by 87 publications

(32 citation statements)

References 40 publications

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“…This enzyme contains TPP, FAD, Mg 2+ and Mn 2+ and generates acetyl-Pi and H 2 O 2 as products. 55,196,197 (C) The CFeSP and methyltransferase (MeTr) MeTr (AcsE) 162 catalyzes transfer of the methyl group of CH 3 -H 4 folate to the Co(I) center in the CFeSP (AcsCD) 198,199 to form the first organometallic intermediate in the Wood-Ljungdahl pathway, CH 3 -Co(III) (Fig. 2).…”

Section: (A) Co Oxidationmentioning

confidence: 99%

Metal centers in the anaerobic microbial metabolism of CO and CO2

et al. 2011

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Carbon dioxide and carbon monoxide are important components of the carbon cycle. Major research efforts are underway to develop better technologies to utilize the abundant greenhouse gas, CO2, for harnessing ‘green’ energy and producing biofuels. One strategy is to convert CO2 into CO, which has been valued for many years as a synthetic feedstock for major industrial processes. Living organisms are masters of CO2 and CO chemistry and, here, we review the elegant ways that metalloenzymes catalyze reactions involving these simple compounds. After describing the chemical and physical properties of CO and CO2, we shift focus to the enzymes and the metal clusters in their active sites that catalyze transformations of these two molecules. We cover how the metal centers on CO dehydrogenase catalyze the interconversion of CO and CO2 and how pyruvate oxidoreductase, which contains thiamin pyrophosphate and multiple Fe4S4 clusters, catalyzes the addition and elimination of CO2 during intermediary metabolism. We also describe how the nickel center at the active site of acetyl-CoA synthase utilizes CO to generate the central metabolite, acetyl-CoA, as part of the Wood-Ljungdahl pathway, and how CO is channelled from the CO dehydrogenase to the acetyl-CoA synthase active site. We cover how the corrinoid iron–sulfur protein interacts with acetyl-CoA synthase. This protein uses vitamin B12 and a Fe4S4 cluster to catalyze a key methyltransferase reaction involving an organometallic methyl-Co3+ intermediate. Studies of CO and CO2 enzymology are of practical significance, and offer fundamental insights into important biochemical reactions involving metallocenters that act as nucleophiles to form organometallic intermediates and catalyze C–C and C–S bond formations.

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Section: (A) Co Oxidationmentioning

confidence: 99%

Metal centers in the anaerobic microbial metabolism of CO and CO2

et al. 2011

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“…Upon arrival at the so-called proximal nickel center, Ni P , CO is combined with a methyl group and CoA to form the important metabolite and cellular building block, acetyl-CoA . In the absence of CoA, slow hydrolysis occurs to give acetate. − While CO is known to strongly inhibit a number of enzyme systems and model compounds because of its high affinity for electron-rich systems and ability to accept metal d-electrons through π-back-bonding interactions, it is an important component in the ACS system, forming a reactive metal–carbonyl species that undergoes a reversible migratory insertion reaction upon methyl addition . The enzymatic process thus mirrors the reaction performed in the commercially valuable Monsanto and Cativa processes for acetic acid synthesis, which require expensive rhodium or iridium catalysts .…”

Section: Introductionmentioning

confidence: 99%

Multielectron Chemistry within a Model Nickel Metalloprotein: Mechanistic Implications for Acetyl-CoA Synthase

et al. 2017

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The acetyl coenzyme A synthase (ACS) enzyme plays a central role in the metabolism of anaerobic bacteria and archaea, catalyzing the reversible synthesis of acetyl-CoA from CO and a methyl group through a series of nickel-based organometallic intermediates. Owing to the extreme complexity of the native enzyme systems, the mechanism by which this catalysis occurs remains poorly understood. In this work, we have developed a protein-based model for the Ni center of acetyl coenzyme A synthase using a nickel-substituted azurin protein (NiAz). NiAz is the first model nickel protein system capable of accessing three (Ni/Ni/Ni) distinct oxidation states within a physiological potential range in aqueous solution, a critical feature for achieving organometallic ACS activity, and binds CO and -CH groups with biologically relevant affinity. Characterization of the Ni-CO species through spectroscopic and computational techniques reveals fundamentally similar features between the model NiAz system and the native ACS enzyme, highlighting the potential for related reactivity in this model protein. This work provides insight into the enzymatic process, with implications toward engineering biological catalysts for organometallic processes.

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“…The corrinoid iron-sulfur protein is a heterodimeric protein with subunits of 33 kDa and 55 kDa [30,31]. The N terminus region of the larger subunit hosts a [4Fe-4S] 2+/1+ cluster that is involved in reductive activation of the cobalt center [32,33].…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of a methyltetrahydrofolate- and corrinoid-dependent methyltransferase

et al. 2000

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The MeTr structure consists of a TIM barrel that embeds methyl-H4folate and cobamide. All related methyltransferases are predicted to fold into a similar TIM barrel pattern and have a similar pterin and cobamide binding site. The observed structure is consistent with either a 'front' (N5) or 'back' (C8a) side protonation of CH3-H4folate, a key step that enhances the electrophilic character of the methyl group, activating it for nucleophilic attack by Co(I).

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Acetate synthesis from carbon monoxide by Clostridium thermoaceticum. Purification of the corrinoid protein.

Cited by 87 publications

References 40 publications

Metal centers in the anaerobic microbial metabolism of CO and CO2

Metal centers in the anaerobic microbial metabolism of CO and CO2

Multielectron Chemistry within a Model Nickel Metalloprotein: Mechanistic Implications for Acetyl-CoA Synthase

Crystal structure of a methyltetrahydrofolate- and corrinoid-dependent methyltransferase

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