A5076704150- Metal-Catalyzed Oxygenation Mechanisms
- Metal complexes synthesis and properties
- Porphyrin Metabolism and Disorders
- Photosynthetic Processes and Mechanisms
- Metalloenzymes and iron-sulfur proteins
- Microbial metabolism and enzyme function
- Heme Oxygenase-1 and Carbon Monoxide
- Porphyrin and Phthalocyanine Chemistry
- Electron Spin Resonance Studies
- Hemoglobin structure and function
- Microbial bioremediation and biosurfactants
- CO2 Reduction Techniques and Catalysts
- Enzyme Structure and Function
- Inorganic and Organometallic Chemistry
- Analytical Chemistry and Chromatography
- Molecular Sensors and Ion Detection
- Various Chemistry Research Topics
- Folate and B Vitamins Research
- Vanadium and Halogenation Chemistry
- Amino Acid Enzymes and Metabolism
- Cassava research and cyanide
- Advanced oxidation water treatment
- Chemical Reaction Mechanisms
- Microbial Metabolic Engineering and Bioproduction
- Synthesis and Catalytic Reactions
Pennsylvania State University
2016-2025
Massachusetts Institute of Technology
1989-2013
Milbank Memorial Fund
2010-2011
University of Illinois Urbana-Champaign
2010
University of Bonn
2010
Harvard University
1995-2010
Stanford University
2000-2007
Emory University
1997-2007
College of Charleston
2003-2007
Texas A&M University
2007
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;...
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,...
Incubation of the apoB2 subunit Escherichia coli ribonucleotide reductase with Fe 2+ and O 2 produces native B2, which contains tyrosyl radical-dinuclear iron cluster cofactor required for nucleotide reduction. The chemical mechanism this reconstitution reaction was investigated by stopped-flow absorption spectroscopy rapid freeze-quench EPR (electron paramagnetic resonance) spectroscopy. Two novel intermediates have been detected in reaction. first exhibits a broad band centered at 565...
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...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT2'-Deoxy-2'-methylenecytidine and 2'-deoxy-2',2'-difluorocytidine 5'-diphosphates: potent mechanism-based inhibitors of ribonucleotide reductaseC. H. Baker, J. Banzon, M. Bollinger, Stubbe, V. Samano, Robins, B. Lippert, E. Jarvi, R. ResvickCite this: Med. Chem. 1991, 34, 6, 1879–1884Publication Date (Print):June 1, 1991Publication History Published online1 May 2002Published inissue 1 June...
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...
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...
Ribonucleotide reductase from Escherichia coli catalyzes the conversion of nucleotides to deoxynucleotides. Multiple cysteins have been postulated play a key role in this process. To test various cysteines nucleotide reduction, variety single and double mutants R1 subunit were prepared: C754S, C759S, C754-759S, C462S, C462A, C230S, C292S. Due expression system, each mutant contains small amounts contaminating wt-R1 (estimated be 1.5-3% based on activity). An epitope tagging method...
SoxR protein of Escherichia coli is activated by superoxide-generating agents or nitric oxide as a powerful transcription activator the soxS gene, whose product activates ∼10 other promoters. contains non-heme iron essential for abortive initiation in vitro. Here we show that this metal dependence extends to full-length In presence E. σ70 RNA polymerase, iron-containing mediates open complex formation at promoter, determined using footprinting with Cu-5-phenyl-1,10-phenanthroline. We...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of Assembly the Tyrosyl Radical-Diiron(III) Cofactor E. Coli Ribonucleotide Reductase: 1. Moessbauer Characterization Diferric Radical PrecursorNatarajan Ravi, J. Martin Bollinger Jr., Boi Hanh Huynh, JoAnne Stubbe, and Dale EdmondsonCite this: Am. Chem. Soc. 1994, 116, 18, 8007–8014Publication Date (Print):September 1, 1994Publication History Published online1 May 2002Published inissue 1 September...
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...
The second of two reactions in a recently discovered pathway through which saturated fatty acids are converted to alkanes (and unsaturated alkenes) cyanobacteria entails scission the C1-C2 bond aldehyde intermediate by enzyme decarbonylase (AD), ferritin-like protein with dinuclear metal cofactor unknown composition. We tested for and failed detect carbon monoxide (CO), proposed C1-derived coproduct alkane synthesis, following vitro conversion octadecanal (R-CHO, where R = n-C(17)H(35))...