Spectroscopic Studies of Mononuclear Molybdenum Enzyme Centers

Kirk, Martin L.; Hille, Russ

doi:10.3390/molecules27154802

Cited by 8 publications

(6 citation statements)

References 154 publications

(223 reference statements)

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“…However, in the place of the S-coordinated cysteine residue of SO, XO active site harbours a terminal sulfido group to accept the xanthine H(8) and make its labile oxide group capable of carrying out a nucleophilic attack (instead of undergo a nucleophilic attack as in SO). Briefly, XO catalysis (Figure 3c) [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] The enzymes from the DMSOR family, in spite of having its active site molybdenum ion coordinated by two molecules of the pyranopterin cofactor (Figure 1), are also suggested to follow the same general OAT mechanism (Figure 2), as illustrated, for example, by bacterial DMSOR itself (Figure 3d) [57][58][59][60][61][62][63][64][65][66][67] or bacterial NaRs [64,[66][67][68][69][70][71][72][73][74][75][76][77][78][79]…”

Section: Context-i: the Molybdenum Sidementioning

confidence: 97%

Bringing Nitric Oxide to the Molybdenum World—A Personal Perspective

Maia

2023

Molecules

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Molybdenum-containing enzymes of the xanthine oxidase (XO) family are well known to catalyse oxygen atom transfer reactions, with the great majority of the characterised enzymes catalysing the insertion of an oxygen atom into the substrate. Although some family members are known to catalyse the “reverse” reaction, the capability to abstract an oxygen atom from the substrate molecule is not generally recognised for these enzymes. Hence, it was with surprise and scepticism that the “molybdenum community” noticed the reports on the mammalian XO capability to catalyse the oxygen atom abstraction of nitrite to form nitric oxide (NO). The lack of precedent for a molybdenum- (or tungsten) containing nitrite reductase on the nitrogen biogeochemical cycle contributed also to the scepticism. It took several kinetic, spectroscopic and mechanistic studies on enzymes of the XO family and also of sulfite oxidase and DMSO reductase families to finally have wide recognition of the molybdoenzymes’ ability to form NO from nitrite. Herein, integrated in a collection of “personal views” edited by Professor Ralf Mendel, is an overview of my personal journey on the XO and aldehyde oxidase-catalysed nitrite reduction to NO. The main research findings and the path followed to establish XO and AO as competent nitrite reductases are reviewed. The evidence suggesting that these enzymes are probable players of the mammalian NO metabolism is also discussed.

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Section: Context-i: the Molybdenum Sidementioning

confidence: 97%

Bringing Nitric Oxide to the Molybdenum World—A Personal Perspective

Maia

2023

Molecules

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“…The recognition of the presence of molybdenum or tungsten and selenium led to a series of spectroscopic studies that were decisive to the early characterization of the FDH active site. Electron paramagnetic resonance spectroscopy (EPR) was thoroughly explored (reviewed recently, for example, in [ 71 , 72 , 73 ]). In fact, the first evidence for the direct binding of selenium to a metal (molybdenum) active site center was obtained precisely with EPR [ 74 , 75 ].…”

Section: Formate Dehydrogenasementioning

confidence: 99%

Selenium—More than Just a Fortuitous Sulfur Substitute in Redox Biology

Maia,

Maiti,

Moura

et al. 2023

Molecules

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Living organisms use selenium mainly in the form of selenocysteine in the active site of oxidoreductases. Here, selenium’s unique chemistry is believed to modulate the reaction mechanism and enhance the catalytic efficiency of specific enzymes in ways not achievable with a sulfur-containing cysteine. However, despite the fact that selenium/sulfur have different physicochemical properties, several selenoproteins have fully functional cysteine-containing homologues and some organisms do not use selenocysteine at all. In this review, selected selenocysteine-containing proteins will be discussed to showcase both situations: (i) selenium as an obligatory element for the protein’s physiological function, and (ii) selenium presenting no clear advantage over sulfur (functional proteins with either selenium or sulfur). Selenium’s physiological roles in antioxidant defence (to maintain cellular redox status/hinder oxidative stress), hormone metabolism, DNA synthesis, and repair (maintain genetic stability) will be also highlighted, as well as selenium’s role in human health. Formate dehydrogenases, hydrogenases, glutathione peroxidases, thioredoxin reductases, and iodothyronine deiodinases will be herein featured.

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“…This type of FDH is much more complex than NAD-FDHs. Indeed, they have more than 700 amino acids arranged in different domains that, in turn, contain several cofactors and/or metal centers such as ferredoxins, heme groups, flavin mononucleotides, etc., depending on the species [ 118 ]. For instance, FDH N from E. coli comprises three domains ( Figure 6 A): the α-domain, which contains the Mo cofactor (see below) and one [4Fe-4S] cluster; the β-domain with four [4Fe-4S] centers; and the γ-domain, with two b -hemes ( Figure 6 B) [ 119 ].…”

Section: Formate Dehydrogenases: Natural Machines For Reducing Comentioning

confidence: 99%

Direct Biocatalytic Processes for CO2 Capture as a Green Tool to Produce Value-Added Chemicals

et al. 2023

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Direct biocatalytic processes for CO2 capture and transformation in value-added chemicals may be considered a useful tool for reducing the concentration of this greenhouse gas in the atmosphere. Among the other enzymes, carbonic anhydrase (CA) and formate dehydrogenase (FDH) are two key biocatalysts suitable for this challenge, facilitating the uptake of carbon dioxide from the atmosphere in complementary ways. Carbonic anhydrases accelerate CO2 uptake by promoting its solubility in water in the form of hydrogen carbonate as the first step in converting the gas into a species widely used in carbon capture storage and its utilization processes (CCSU), particularly in carbonation and mineralization methods. On the other hand, formate dehydrogenases represent the biocatalytic machinery evolved by certain organisms to convert CO2 into enriched, reduced, and easily transportable hydrogen species, such as formic acid, via enzymatic cascade systems that obtain energy from chemical species, electrochemical sources, or light. Formic acid is the basis for fixing C1-carbon species to other, more reduced molecules. In this review, the state-of-the-art of both methods of CO2 uptake is assessed, highlighting the biotechnological approaches that have been developed using both enzymes.

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Spectroscopic Studies of Mononuclear Molybdenum Enzyme Centers

Cited by 8 publications

References 154 publications

Bringing Nitric Oxide to the Molybdenum World—A Personal Perspective

Bringing Nitric Oxide to the Molybdenum World—A Personal Perspective

Selenium—More than Just a Fortuitous Sulfur Substitute in Redox Biology

Direct Biocatalytic Processes for CO2 Capture as a Green Tool to Produce Value-Added Chemicals

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