A5050467129- Metal-Catalyzed Oxygenation Mechanisms
- Metalloenzymes and iron-sulfur proteins
- Porphyrin Metabolism and Disorders
- Microbial metabolism and enzyme function
- Photosynthetic Processes and Mechanisms
- Metal complexes synthesis and properties
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Heme Oxygenase-1 and Carbon Monoxide
- Hemoglobin structure and function
- Porphyrin and Phthalocyanine Chemistry
- Magnetism in coordination complexes
- Nitric Oxide and Endothelin Effects
- Microbial bioremediation and biosurfactants
- Trace Elements in Health
- CO2 Reduction Techniques and Catalysts
- Enzyme Structure and Function
- Electron Spin Resonance Studies
- Folate and B Vitamins Research
- RNA modifications and cancer
- Lanthanide and Transition Metal Complexes
- Electrocatalysts for Energy Conversion
- Biochemical and Molecular Research
- Vanadium and Halogenation Chemistry
- Advanced oxidation water treatment
Pennsylvania State University
2016-2025
Park University
2007-2022
Howard Hughes Medical Institute
1999-2016
École Polytechnique
2014
Massachusetts Institute of Technology
1998-2013
University of Bonn
2010
Pomona College
2010
Emory University
1998-2009
Universidade Nova de Lisboa
1998-2009
Stockholm University
2009
The Fe(II)- and alpha-ketoglutarate(alphaKG)-dependent dioxygenases have roles in synthesis of collagen sensing oxygen mammals, acquisition nutrients antibiotics microbes, repair alkylated DNA both. A consensus mechanism for these enzymes, involving (i) addition O(2) to a five-coordinate, (His)(2)(Asp)-facially coordinated Fe(II) center which alphaKG is also bound via its C-1 carboxylate ketone oxygen; (ii) attack the uncoordinated on carbonyl form bicyclic Fe(IV)-peroxyhemiketal complex;...
Iron−sulfur cluster biosynthesis in both prokaryotic and eukaryotic cells is known to be mediated by two highly conserved proteins, termed IscS IscU prokaryotes. The homodimeric protein has been shown a cysteine desulfurase that catalyzes the reductive conversion of alanine sulfide. In this work, time course IscS-mediated Fe−S assembly was monitored via anaerobic anion exchange chromatography. nature properties clusters assembled discrete fractions were assessed analytical studies together...
The Fe(II)- and α-ketoglutarate-dependent dioxygenases catalyze hydroxylation reactions of considerable biomedical environmental significance. Recently, the first oxidized iron intermediate in reaction a member this family, taurine:α-ketoglutarate dioxygenase (TauD), was detected shown to be high-spin, formally Fe(IV) complex. demonstration study that decay complex is ∼30-fold slower when it formed presence 1-[2H]2-taurine provides evidence abstracts hydrogen from C1, site hydroxylation,...
The Fe(II)- and α-ketoglutarate (αKG)-dependent dioxygenases use mononuclear nonheme iron centers to effect hydroxylation of their substrates decarboxylation cosubstrate, αKG, CO 2 succinate. Our recent dissection the mechanism taurine:αKG dioxygenase (TauD), a member this enzyme family, revealed that two transient complexes accumulate during catalysis in presence saturating substrates. first complex contains long-postulated C-H-cleaving Fe(IV)-oxo intermediate, J, second is an...
The Fe(II)- and α-ketoglutarate-dependent dioxygenases catalyze hydroxylation reactions of considerable biomedical environmental significance. Recently, the first oxidized iron intermediate in reaction a member this family, taurine:α-ketoglutarate dioxygenase (TauD), was detected shown to be high-spin Fe(IV) complex. In study we have used X-ray absorption spectroscopy demonstrate presence short (1.62 Å) interaction between one its ligands but not Fe(II) starting detection strongly...
The α-ketoglutarate-dependent hydroxylases and halogenases employ similar reaction mechanisms involving hydrogen-abstracting Fe(IV)-oxo (ferryl) intermediates. In the halogenases, carboxylate residue from His 2 (Asp/Glu) 1 “facial triad” of iron ligands found in is replaced by alanine, a halide ion (X − ) coordinates at vacated site. Halogenation thought to result “rebound” halogen radical X-Fe(III)-OH intermediate produced hydrogen (H • abstraction substrate radical. alternative decay...
An IscA homologue within the nif regulon of Azotobacter vinelandii, designated NifIscA, was expressed in Escherichia coli and purified to homogeneity. Purified NifIscA found be a homodimer 11-kDa subunits that contained no metal centers or other prosthetic groups its as-isolated form. Possible roles for Fe−S cluster biosynthesis were assessed by investigating ability bind iron assemble clusters NifS-directed process, as monitored combination UV−vis absorption, Mössbauer, resonance Raman,...
Aliphatic halogenases activate O(2), cleave alpha-ketoglutarate (alphaKG) to CO(2) and succinate, form haloferryl [X-Fe(IV)O; X = Cl or Br] complexes that aliphatic C-H bonds install halogens during the biosynthesis of natural products by non-ribosomal peptide synthetases (NRPSs). For related alphaKG-dependent dioxygenases, it has been shown reaction Fe(II) cofactor with O(2) bond-cleaving ferryl complex is "triggered" binding target substrate. In this study, we have tested for defined...
Methylation of small molecules and macromolecules is crucial in metabolism, cell signaling, epigenetic programming most often achieved by S-adenosylmethionine (SAM)-dependent methyltransferases. Most employ an S(N)2 mechanism to methylate nucleophilic sites on their substrates, but recently, radical SAM enzymes have been identified that carbon atoms are not inherently via the intermediacy a 5'-deoxyadenosyl 5'-radical. We determined mechanisms two such reactions targeting sp(2)-hybridized...
The heme domain (iNOS(heme)) of inducible nitric oxide synthase (NOS) was expressed in Escherichia coli and purified to homogeneity. Rapid freeze-quench (RFQ) EPR used monitor the reaction reduced iNOS(heme) with oxygen presence absence substrate. In these reactions, oxidation occurs at a rate approximately 15 s(-)(1) 4 degrees C. A transient species g = 2.0 signal is also observed under conditions. spectral properties are those an anisotropic organic radical S (1)/(2). Comparison spectra...
The Fe(II)- and α-ketoglutarate (αKG)-dependent dioxygenases activate O2 for cleavage of unactivated C−H bonds in their substrates. key intermediate that abstracts hydrogen the reaction taurine:αKG dioxygenase (TauD), a member this enzyme family, was recently characterized. intermediate, denoted J, shown to contain an iron(IV)-oxo unit. Other important structural features such as number, identity, disposition ligands Fe(IV) coordination sphere, are not yet understood. To probe these...
In a conventional class I ribonucleotide reductase (RNR), diiron(II/II) cofactor in the R2 subunit reacts with oxygen to produce diiron(III/IV) intermediate, which generates stable tyrosyl radical (Y⚫). The Y⚫ reversibly oxidizes cysteine residue R1 cysteinyl (C⚫), abstracts 3′-hydrogen of substrate initiate its reduction. RNR from Chlamydia trachomatis lacks Y⚫, and it had been proposed that complex directly C⚫ R1. By enzyme activity measurements spectroscopic methods, we show this actually...
Recent studies on taurine:α-ketoglutarate dioxygenase (TauD) from Escherichia coli have provided evidence for a three-step, minimal kinetic mechanism involving the quaternary TauD·Fe(II)·α-ketoglutarate·taurine complex, taurine-hydroxylating Fe(IV)−oxo intermediate (J) that forms upon reaction of complex with O2, and poorly defined, Fe(II)-containing state converts in rate-limiting step back to [Price, J. C., Barr, E. W., Tirupati, B., Bollinger, M., Jr., Krebs, C. (2003) Biochemistry 42,...
Abstract The iron( II )‐ and α‐ketoglutarate‐dependent dioxygenases comprise enzymes that catalyze a variety of important reactions in biology, including steps the biosynthesis collagen antibiotics, degradation xenobiotics, repair alkylated DNA, sensing oxygen response to hypoxia. In these reactions, reductive activation is coupled hydroxylation substrate decarboxylation co‐substrate, α‐ketoglutarate. It believed single, conserved mechanistic pathway for formation high‐valent iron...
Tyrosine hydroxylase, a member of the aromatic amino acid hydroxylase family, uses mononuclear Fe(II) and tetrahydropterin for hydroxylation tyrosine to dihydroxyphenylalanine. Rapid-freeze quench Mössbauer spectroscopy has now provided direct evidence presence an Fe(IV) intermediate in reaction catalyzed by hydroxylase. Rapid-quench techniques provide support kinetic competence this species as hydroxylating intermediate. This is first enzymatic reaction.
Experimental data exists for only a vanishingly small fraction of sequenced microbial genes. This community page discusses the progress made by COMBREX project to address this important issue using both computational and experimental resources.
The complex of the mononuclear non-heme halogenase CytC3 from Streptomyces, Fe(II), α-ketoglutarate, bromide, and substrate l-2-aminobutyryl-S-CytC2 reacts with O2 to form a reaction intermediate. Variable-field, freeze-quench Mössbauer spectroscopy reveals this intermediate be mixture two high-spin Fe(IV) complexes in an approximate 3.7/1 ratio. Freeze-quench Fe K-edge X-ray absorption provides further insight into structure A short 1.62-Å interaction between one its ligands is attributed...