Production of Dioxygen in the Dark: Dismutases of Oxyanions

DuBois, Jennifer L.; Ojha, Sunil

doi:10.1007/978-3-319-12415-5_3

Cited by 11 publications

(21 citation statements)

References 154 publications

(203 reference statements)

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“… 480 In nature, the decomposition of chlorite is catalyzed by chlorite dismutase (Cld), a heme-containing protein with a histidine proximal ligand. 481 The active site structure of Cld is shown in Figure 50 , which is featured by an arginine positioned above the heme and the lack of other hydrogen-bonding residues that are essential for O–O bond heterolytic cleavage. 482 The proposed mechanism for functional Cld involves an initial formation of a ferric–chlorito intermediate (Fe III –OClO), analogous to compounds 0 in P450s and peroxidases ( Figure 50 c).…”

Section: C–h Functionalization Reactions Mediated By Oxoiron(iv) Porpmentioning

confidence: 99%

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

2017

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As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal–oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal–oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron–oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs.

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Section: C–h Functionalization Reactions Mediated By Oxoiron(iv) Porpmentioning

confidence: 99%

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

2017

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“…10 Kp Cld and perhaps Clds from other non-perchlorate-respiring species may therefore be part of a system that protects against the effects of environmental ClO 4 − or ClO 3 − , each of which has minute but ubiquitous natural sources. 1, 25, 26 …”

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confidence: 99%

Active Sites of O₂-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron–Ligand Vibrational Correlations

et al. 2017

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O2-evolving chlorite dismutases (Clds) fall into two subfamilies, which efficiently convert ClO2− to O2 and Cl−. The Cld from Dechloromonas aromatica (DaCld) represents the chlorite-decomposing homopentameric enzymes found in perchlorate and chlorate respiring bacteria. The Cld from the Gram-negative, human pathogen Klebsiella pneumoniae (KpCld) is representative of the second subfamily, comprising homodimeric enzymes having truncated N-termini. Here steric and nonbonding properties of the DaCld and KpCld active sites have been probed via kinetic, thermodynamic and spectroscopic behaviors of their fluorides, chlorides and hydroxides. Cooperative Cl− binding to KpCld drives formation of a hexacoordinate, high-spin aqua heme, whereas DaCld remains pentacoordinate and high-spin under analogous conditions. Fluoride coordinates to the heme iron in KpCld and DaCld, exhibiting ν(FeIII−F) bands at 385 and 390 cm−1, respectively. Correlation of these frequencies with their CT1 energies reveals strong H-bond-donation to the F− ligand, indicating that atoms directly coordinated to heme iron are accessible by distal H-bond donation. New vibrational frequency correlations between either ν(FeIII−F) or ν(FeIII−OH) and ν(FeII−His) of Clds and other heme proteins are reported. These correlations orthogonalize proximal and distal effects on the bonding between iron and exogenous π-donor ligands. The axial Fe−X vibrations and the relationships between them illuminate both similarities and differences in the H-bonding and electrostatic properties of the distal and proximal heme environments in pentameric and dimeric Clds. Moreover, they provide general insight into the structural basis of reactivity toward substrates in heme-dependent enzymes and their mechanistic intermediates, especially those containing the ferryl moiety.

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“…The immense diversity of Cld and Cld-like proteins and their presence throughout the tree of life have received particular attention over the last few years (Maixner et al, 2008; Mlynek et al, 2011). Recent reviews on functionally efficient Cld and Cld-like proteins discussed evolutionary, biochemical and biophysical aspects as well as their biotechnological potential (Hofbauer et al, 2014; DuBois and Ojha, 2015; Wang and Coates, 2017). The discovery of a Cld in the nitrite-oxidizing Nitrospira defluvii (Maixner et al, 2008) was the first example of a functional Cld in a bacterium incapable of chlorine oxyanion reduction.…”

Section: Microbial Metabolism Of Chlorine Oxyanionsmentioning

confidence: 99%

Microbial Synthesis and Transformation of Inorganic and Organic Chlorine Compounds

et al. 2018

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Organic and inorganic chlorine compounds are formed by a broad range of natural geochemical, photochemical and biological processes. In addition, chlorine compounds are produced in large quantities for industrial, agricultural and pharmaceutical purposes, which has led to widespread environmental pollution. Abiotic transformations and microbial metabolism of inorganic and organic chlorine compounds combined with human activities constitute the chlorine cycle on Earth. Naturally occurring organochlorines compounds are synthesized and transformed by diverse groups of (micro)organisms in the presence or absence of oxygen. In turn, anthropogenic chlorine contaminants may be degraded under natural or stimulated conditions. Here, we review phylogeny, biochemistry and ecology of microorganisms mediating chlorination and dechlorination processes. In addition, the co-occurrence and potential interdependency of catabolic and anabolic transformations of natural and synthetic chlorine compounds are discussed for selected microorganisms and particular ecosystems.

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Production of Dioxygen in the Dark: Dismutases of Oxyanions

Cited by 11 publications

References 154 publications

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

Active Sites of O₂-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron–Ligand Vibrational Correlations

Microbial Synthesis and Transformation of Inorganic and Organic Chlorine Compounds

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Production of Dioxygen in the Dark: Dismutases of Oxyanions

Cited by 11 publications

References 154 publications

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

Active Sites of O2-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron–Ligand Vibrational Correlations

Microbial Synthesis and Transformation of Inorganic and Organic Chlorine Compounds

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Active Sites of O₂-Evolving Chlorite Dismutases Probed by Halides and Hydroxides and New Iron–Ligand Vibrational Correlations