Wilfred R. Hagen
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View article: The g-Strained EPR Line Shape of Transition-Ion Complexes and Metalloproteins: Four Decades of Misunderstanding and Its Consequences
The g-Strained EPR Line Shape of Transition-Ion Complexes and Metalloproteins: Four Decades of Misunderstanding and Its Consequences Open
Analysis of the EPR of dilute transition-ion complexes and metalloproteins in random phases, such as frozen solutions, powders, glasses, and gels, requires a model for the spectral ‘powder’ shape. Such a model comprises a description of th…
View article: Employing microalga Chlorella sorokiniana in the biosynthesis of paramagnetic and catalytically functional manganese cluster
Employing microalga Chlorella sorokiniana in the biosynthesis of paramagnetic and catalytically functional manganese cluster Open
Finding vehicles for biosynthesis of metal clusters with advantageous magnetic and catalytic properties is an important industrial and environmental task. We have found previously that green microalga Chlorella sorokiniana produces a multi…
View article: Quantum Magnetism of the Iron Core in Ferritin Proteins—A Re-Evaluation of the Giant-Spin Model
Quantum Magnetism of the Iron Core in Ferritin Proteins—A Re-Evaluation of the Giant-Spin Model Open
The electron–electron, or zero-field interaction (ZFI) in the electron paramagnetic resonance (EPR) of high-spin transition ions in metalloproteins and coordination complexes, is commonly described by a simple spin Hamiltonian that is seco…
View article: Broadband EPR Spectroscopy of the Triplet State: Multi-Frequency Analysis of Copper Acetate Monohydrate
Broadband EPR Spectroscopy of the Triplet State: Multi-Frequency Analysis of Copper Acetate Monohydrate Open
Electron paramagnetic resonance spectroscopy is a long-standing method for the exploration of electronic structures of transition ion complexes. The difficulty of its analysis varies considerably, not only with the nature of the spin syste…
View article: A Comparative Multi-Frequency EPR Study of Dipolar Interaction in Tetra-Heme Cytochromes
A Comparative Multi-Frequency EPR Study of Dipolar Interaction in Tetra-Heme Cytochromes Open
Distances between Fe ions in multiheme cytochromes are sufficiently short to make the intramolecular dipole-dipole interaction between hemes probable. In the analysis of EPR data from cytochromes, this interaction has thus far been ignored…
View article: Conversion of a Single-Frequency X-Band EPR Spectrometer into a Broadband Multi-Frequency 0.1–18 GHz Instrument for Analysis of Complex Molecular Spin Hamiltonians
Conversion of a Single-Frequency X-Band EPR Spectrometer into a Broadband Multi-Frequency 0.1–18 GHz Instrument for Analysis of Complex Molecular Spin Hamiltonians Open
A broadband EPR spectrometer is an instrument that can be tuned to many microwave frequencies over several octaves. Its purpose is the collection of multi-frequency data, whose global analysis affords interpretation of complex spectra by m…
View article: The Development of Tungsten Biochemistry—A Personal Recollection
The Development of Tungsten Biochemistry—A Personal Recollection Open
The development of tungsten biochemistry is sketched from the viewpoint of personal participation. Following its identification as a bio-element, a catalogue of genes, enzymes, and reactions was built up. EPR spectroscopic monitoring of re…
View article: Radical-SAM dependent nucleotide dehydratase (SAND), rectification of the names of an ancient iron-sulfur enzyme using NC-IUBMB recommendations
Radical-SAM dependent nucleotide dehydratase (SAND), rectification of the names of an ancient iron-sulfur enzyme using NC-IUBMB recommendations Open
We highlight the importance of introducing systemic names for enzymes using EC classification and the ever-growing problem of protein names. Here, we tackle one specific case of iron-sulfur ([FeS]) enzymes. We show that the language used t…
View article: Low-frequency EPR of ferrimyoglobin fluoride and ferrimyoglobin cyanide: a case study on the applicability of broadband analysis to high-spin hemoproteins and to HALS hemoproteins
Low-frequency EPR of ferrimyoglobin fluoride and ferrimyoglobin cyanide: a case study on the applicability of broadband analysis to high-spin hemoproteins and to HALS hemoproteins Open
View article: Electron paramagnetic resonance proof for the existence of molecular hydrino
Electron paramagnetic resonance proof for the existence of molecular hydrino Open
Quantum mechanics postulates that the hydrogen atom has a stable ground state from which it can be promoted to excited states by capture of electromagnetic radiation, with the energy of all possible states given by En = −13.598/…
View article: Iron–sulfur clusters as inhibitors and catalysts of viral replication
Iron–sulfur clusters as inhibitors and catalysts of viral replication Open
View article: Structure and function of the hybrid cluster protein
Structure and function of the hybrid cluster protein Open
View article: Maximum iron loading of ferritin: half a century of sustained citation distortion
Maximum iron loading of ferritin: half a century of sustained citation distortion Open
Analysis of citation networks in biomedical research has indicated that belief in a specific scientific claim can gain unfounded authority through citation bias (systematic ignoring of papers that contain content conflicting with a claim),…
View article: Unique Biradical Intermediate in the Mechanism of the Heme Enzyme Chlorite Dismutase
Unique Biradical Intermediate in the Mechanism of the Heme Enzyme Chlorite Dismutase Open
The heme enzyme chlorite dismutase (Cld) catalyzes O-O bond formation as part of the conversion of the toxic chlorite (ClO2 -) to chloride (Cl-) and molecular oxygen (O2). Enzymatic O-O bond form…
View article: Review for "Crystal structure of Escherichia coli class II hybrid cluster protein, HCP, reveals a [4Fe‐4S] cluster at the N‐terminal protrusion"
Review for "Crystal structure of Escherichia coli class II hybrid cluster protein, HCP, reveals a [4Fe‐4S] cluster at the N‐terminal protrusion" Open
View article: Very Low-Frequency Broadband Electron Paramagnetic Resonance Spectroscopy of Metalloproteins
Very Low-Frequency Broadband Electron Paramagnetic Resonance Spectroscopy of Metalloproteins Open
A previously developed spectrometer for broadband electron paramagnetic resonance (EPR) spectroscopy of dilute randomly oriented systems has been considerably modified to extend the frequency reach down to the hundred MHz range and to boos…
View article: Review for "Crystal structure of Escherichia coli class II hybrid cluster protein, HCP, reveals a [4Fe‐4S] cluster at the N‐terminal protrusion"
Review for "Crystal structure of Escherichia coli class II hybrid cluster protein, HCP, reveals a [4Fe‐4S] cluster at the N‐terminal protrusion" Open
View article: Distinguishing electron paramagnetic resonance signature of molecular hydrino
Distinguishing electron paramagnetic resonance signature of molecular hydrino Open
Quantum mechanics postulates that the hydrogen atom has a stable ground state from which it can be promoted to excited states by capture of electromagnetic radiation, with the energy of all possible states given by En = -13.598/n2 eV, in w…
View article: Trinuclear copper biocatalytic center forms an active site of thiocyanate dehydrogenase
Trinuclear copper biocatalytic center forms an active site of thiocyanate dehydrogenase Open
Biocatalytic copper centers are generally involved in the activation and reduction of dioxygen, with only few exceptions known. Here we report the discovery and characterization of a previously undescribed copper center that forms the acti…
View article: Effect of UV illumination on perylene-doped luminescent solar concentrators: A cautionary tale
Effect of UV illumination on perylene-doped luminescent solar concentrators: A cautionary tale Open
View article: Broadband Tunable Electron Paramagnetic Resonance Spectroscopy of Dilute Metal Complexes
Broadband Tunable Electron Paramagnetic Resonance Spectroscopy of Dilute Metal Complexes Open
Analysis of the electron paramagnetic resonance (EPR) of transition ion complexes requires data taken at different microwave frequencies because the spin Hamiltonian contains operators linear in the frequency as well as operators independe…
View article: EPR spectroscopy of putative enzyme intermediates in the NO reductase and the auto‐nitrosylation reaction of <i>Desulfovibrio vulgaris</i> hybrid cluster protein
EPR spectroscopy of putative enzyme intermediates in the NO reductase and the auto‐nitrosylation reaction of <i>Desulfovibrio vulgaris</i> hybrid cluster protein Open
The hybrid cluster protein (Hcp) contains a unique 4Fe cluster that is a hybrid of μ‐S and μ‐O bridges. Escherichia coli Hcp has recently been found to carry NO reductase activity as well as S ‐nitrosylation activity in NO‐based signaling.…
View article: Distant Non-Obvious Mutations Influence the Activity of a Hyperthermophilic Pyrococcus furiosus Phosphoglucose Isomerase
Distant Non-Obvious Mutations Influence the Activity of a Hyperthermophilic Pyrococcus furiosus Phosphoglucose Isomerase Open
The cupin-type phosphoglucose isomerase (PfPGI) from the hyperthermophilic archaeon Pyrococcus furiosus catalyzes the reversible isomerization of glucose-6-phosphate to fructose-6-phosphate. We investigated PfPGI using protein-engineering …
View article: Hypothesis: entatic<i>versus</i>ecstatic states in metalloproteins
Hypothesis: entatic<i>versus</i>ecstatic states in metalloproteins Open
Biological metal sites are optimized for function by conformational properties of the protein macroligand.
View article: Biliverdin–copper complex at physiological pH
Biliverdin–copper complex at physiological pH Open
In physiological settings, biliverdin and Cu2+build a paramagnetic complex with formal structure: radical cation/Cu1+or radical anion/Cu3+.
View article: EPR spectroscopy of complex biological iron–sulfur systems
EPR spectroscopy of complex biological iron–sulfur systems Open
View article: Fast and accurate enzyme activity measurements using a chip-based microfluidic calorimeter
Fast and accurate enzyme activity measurements using a chip-based microfluidic calorimeter Open
Recent developments in microfluidic and nanofluidic technologies have resulted in development of new chip-based microfluidic calorimeters with potential use in different fields. One application would be the accurate high-throughput measure…
View article: Microsecond time-scale kinetics of transient biochemical reactions
Microsecond time-scale kinetics of transient biochemical reactions Open
To afford mechanistic studies in enzyme kinetics and protein folding in the microsecond time domain we have developed a continuous-flow microsecond time-scale mixing instrument with an unprecedented dead-time of 3.8 ± 0.3 μs. The instrumen…
View article: Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer
Cobamide-mediated enzymatic reductive dehalogenation via long-range electron transfer Open
View article: Spectroscopic evidence for the presence of a high‐valent Fe(<scp>IV</scp>) species in the ferroxidase reaction of an archaeal ferritin
Spectroscopic evidence for the presence of a high‐valent Fe(<span>IV</span>) species in the ferroxidase reaction of an archaeal ferritin Open
A high‐valent Fe( IV ) species is proposed to be generated from the decay of a peroxodiferric intermediate in the catalytic cycle at the di‐iron cofactor center of dioxygen‐activating enzymes such as methane monooxygenase. However, it is b…