Britt Hedman
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View article: Mechanism of O<sub>2</sub> Activation and Cysteine Oxidation by the Unusual Mononuclear Cu(I) Active Site of the Formylglycine-Generating Enzyme
Mechanism of O<sub>2</sub> Activation and Cysteine Oxidation by the Unusual Mononuclear Cu(I) Active Site of the Formylglycine-Generating Enzyme Open
The formylglycine-generating enzyme (FGE) catalyzes the selective oxidation of a peptidyl-cysteine to form formylglycine, a critical cotranslational modification for type I sulfatase activation and a useful bioconjugation handle. Previous …
View article: Experimental electronic structures of the Fe <sup>IV</sup> =O bond in S=1 heme vs. nonheme sites: Effect of the porphyrin ligand
Experimental electronic structures of the Fe <sup>IV</sup> =O bond in S=1 heme vs. nonheme sites: Effect of the porphyrin ligand Open
High-valent Fe IV =O species are common intermediates in biological and artificial catalysts. Heme and nonheme S=1 Fe IV =O sites have been synthesized and studied for decades but little quantitative experimental comparison of their electr…
View article: Synthesis, Structure, and Redox Reactivity of Ni Complexes Bearing a Redox and Acid–Base Non-innocent Ligand with Ni<sup>II</sup>, Ni<sup>III</sup>, and Ni<sup>IV</sup> Formal Oxidation States
Synthesis, Structure, and Redox Reactivity of Ni Complexes Bearing a Redox and Acid–Base Non-innocent Ligand with Ni<sup>II</sup>, Ni<sup>III</sup>, and Ni<sup>IV</sup> Formal Oxidation States Open
A series of Ni complexes bearing a redox and acid-base noninnocent tetraamido macrocyclic ligand, H4-(TAML-4) {H4-(TAML-4) = 15,15-dimethyl-5,8,13,17-tetrahydro-5,8,13,17-tetraaza-dibenzo[a,g]cyclotridecene-6,7,14,16-tetraone}, with formal…
View article: Experimental Definition of the <i>S</i> = 1 π vs <i>S</i> = 2 σ Reactivity and <i>S</i> = 2 Character in the Ground State of an <i>S</i> = 1 Fe<sup>IV</sup>O Complex
Experimental Definition of the <i>S</i> = 1 π vs <i>S</i> = 2 σ Reactivity and <i>S</i> = 2 Character in the Ground State of an <i>S</i> = 1 Fe<sup>IV</sup>O Complex Open
Iron(IV)-oxo intermediates found in iron enzymes and artificial catalysts are competent for H atom abstraction in catalytic cycles. For S = 2 intermediates, both axial and equatorial approaches are well-established. The mechanism for S = 1…
View article: A Codeposition Route to CuI–Pyridine Coordination Complexes for Organic Light-Emitting Diodes
A Codeposition Route to CuI–Pyridine Coordination Complexes for Organic Light-Emitting Diodes Open
We demonstrate a new approach for utilizing CuI coordination complexes as emissive layers in organic light-emitting diodes that involves in situ codeposition of CuI and 3,5-bis(carbazol-9-yl)pyridine (mCPy). With a simple three-layer devic…
View article: Heterologous synthesis of the complex homometallic cores of nitrogenase P- and M-clusters in <i>Escherichia coli</i>
Heterologous synthesis of the complex homometallic cores of nitrogenase P- and M-clusters in <i>Escherichia coli</i> Open
Nitrogenase is an active target of heterologous expression because of its importance for areas related to agronomy, energy, and environment. One major hurdle for expressing an active Mo-nitrogenase in Escherichia coli is to generate the co…
View article: X-ray Spectroscopic Study of the Electronic Structure of a Trigonal High-Spin Fe(IV)═O Complex Modeling Non-Heme Enzyme Intermediates and Their Reactivity
X-ray Spectroscopic Study of the Electronic Structure of a Trigonal High-Spin Fe(IV)═O Complex Modeling Non-Heme Enzyme Intermediates and Their Reactivity Open
Fe K-edge X-ray absorption spectroscopy (XAS) has long been used for the study of high-valent iron intermediates in biological and artificial catalysts. 4p-mixing into the 3d orbitals complicates the pre-edge analysis but when correctly un…
View article: Kβ X-ray Emission Spectroscopy of Cu(I)-Lytic Polysaccharide Monooxygenase: Direct Observation of the Frontier Molecular Orbital for H<sub>2</sub>O<sub>2</sub> Activation
Kβ X-ray Emission Spectroscopy of Cu(I)-Lytic Polysaccharide Monooxygenase: Direct Observation of the Frontier Molecular Orbital for H<sub>2</sub>O<sub>2</sub> Activation Open
Lytic polysaccharide monooxygenases (LPMOs) catalyze the degradation of recalcitrant carbohydrate polysaccharide substrates. These enzymes are characterized by a mononuclear Cu(I) active site with a three-coordinate T-shaped "His-brace" co…
View article: Tuning the Type 1 Reduction Potential of Multicopper Oxidases: Uncoupling the Effects of Electrostatics and H-Bonding to Histidine Ligands
Tuning the Type 1 Reduction Potential of Multicopper Oxidases: Uncoupling the Effects of Electrostatics and H-Bonding to Histidine Ligands Open
In multicopper oxidases (MCOs), the type 1 (T1) Cu accepts electrons from the substrate and transfers these to the trinuclear Cu cluster (TNC) where O2 is reduced to H2O. The T1 potential in MCOs varies from 340 to 780 mV, a range not expl…
View article: Methane Activation by a Mononuclear Copper Active Site in the Zeolite Mordenite: Effect of Metal Nuclearity on Reactivity
Methane Activation by a Mononuclear Copper Active Site in the Zeolite Mordenite: Effect of Metal Nuclearity on Reactivity Open
The direct conversion of methane to methanol would have a wide reaching environmental and industrial impact. Copper-containing zeolites can perform this reaction at low temperatures and pressures at a previously defined O2-activated [Cu2O]…
View article: Incorporation of an Asymmetric Mo−Fe−S Cluster as an Artificial Cofactor into Nitrogenase
Incorporation of an Asymmetric Mo−Fe−S Cluster as an Artificial Cofactor into Nitrogenase Open
Nitrogenase employs a sophisticated electron transfer system and a Mo−Fe−S−C cofactor, designated the M‐cluster [(cit)MoFe 7 S 9 C]), to reduce atmospheric N 2 to bioaccessible NH 3 . Previously, we have shown that the cofactor‐free form o…
View article: Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer. Corrigendum
Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer. Corrigendum Open
A figure in the article by Huyke et al. [(2021), J. Synchrotron Rad. 28 , 1100–1113] is corrected.
View article: Characterization of a Nitrogenase Iron Protein Substituted with a Synthetic [Fe<sub>4</sub>Se<sub>4</sub>] Cluster
Characterization of a Nitrogenase Iron Protein Substituted with a Synthetic [Fe<sub>4</sub>Se<sub>4</sub>] Cluster Open
The Fe protein of nitrogenase plays multiple roles in substrate reduction and cluster maturation via its redox‐active [Fe 4 S 4 ] cluster. Here we report the synthesis and characterization of a water‐soluble [Fe 4 Se 4 ] cluster that is us…
View article: CCDC 2121572: Experimental Crystal Structure Determination
CCDC 2121572: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer
Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer Open
Determination of electronic structures during chemical reactions remains challenging in studies which involve reactions in the millisecond timescale, toxic chemicals, and/or anaerobic conditions. In this study, a three-dimensionally (3D) m…
View article: Effect of 3d/4p Mixing on 1s2p Resonant Inelastic X-ray Scattering: Electronic Structure of Oxo-Bridged Iron Dimers
Effect of 3d/4p Mixing on 1s2p Resonant Inelastic X-ray Scattering: Electronic Structure of Oxo-Bridged Iron Dimers Open
1s2p resonant inelastic X-ray scattering (1s2p RIXS) has proven successful in the determination of the differential orbital covalency (DOC, the amount of metal vs ligand character in each d molecular orbital) of highly covalent centrosymme…
View article: CCDC 2057574: Experimental Crystal Structure Determination
CCDC 2057574: Experimental Crystal Structure Determination Open
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available …
View article: A Thioether-Ligated Cupric Superoxide Model with Hydrogen Atom Abstraction Reactivity
A Thioether-Ligated Cupric Superoxide Model with Hydrogen Atom Abstraction Reactivity Open
The central role of cupric superoxide intermediates proposed in hormone and neurotransmitter biosynthesis by noncoupled binuclear copper monooxygenases like dopamine-β-monooxygenase has drawn significant attention to the unusual methionine…
View article: Kβ X-ray Emission Spectroscopy as a Probe of Cu(I) Sites: Application to the Cu(I) Site in Preprocessed Galactose Oxidase
Kβ X-ray Emission Spectroscopy as a Probe of Cu(I) Sites: Application to the Cu(I) Site in Preprocessed Galactose Oxidase Open
Cu(I) active sites in metalloproteins are involved in O2 activation, but their O2 reactivity is difficult to study due to the Cu(I) d10 closed shell which precludes the use of conventional spectroscopic methods. Kβ X-ray emission spectrosc…
View article: Evaluation of a concerted vs. sequential oxygen activation mechanism in α-ketoglutarate–dependent nonheme ferrous enzymes
Evaluation of a concerted vs. sequential oxygen activation mechanism in α-ketoglutarate–dependent nonheme ferrous enzymes Open
Significance Many iron-dependent enzymes utilize molecular oxygen to functionalize inert C–H bonds in biology. Nonheme ferrous enzymes perform these reactions by reducing dioxygen, often in the presence of a sacrificial electron donor, to …
View article: Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the “9<sup>th</sup> Sulfur”
Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the “9<sup>th</sup> Sulfur” Open
Nitrogenases catalyze the reduction of N 2 to NH 4 + at its cofactor site. Designated the M‐cluster, this [MoFe 7 S 9 C( R ‐homocitrate)] cofactor is synthesized via the transformation of a [Fe 4 S 4 ] cluster pair into an [Fe 8 S 9 C] pre…
View article: Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the “9<sup>th</sup> Sulfur”
Spectroscopic Characterization of an Eight‐Iron Nitrogenase Cofactor Precursor that Lacks the “9<sup>th</sup> Sulfur” Open
Nitrogenases catalyze the reduction of N 2 to NH 4 + at its cofactor site. Designated the M‐cluster, this [MoFe 7 S 9 C( R ‐homocitrate)] cofactor is synthesized via the transformation of a [Fe 4 S 4 ] cluster pair into an [Fe 8 S 9 C] pre…
View article: Stanford-SLAC Cryo-EM Center (S<sup>2</sup>C<sup>2</sup>)
Stanford-SLAC Cryo-EM Center (S<sup>2</sup>C<sup>2</sup>) Open
Journal Article Stanford-SLAC Cryo-EM Center (S2C2) Get access Wah Chiu, Wah Chiu CryoEM and Bioimaging Division, Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 USADepartment of Bioen…