Flavonol dioxygenase chemistry mediated by a synthetic nickel superoxide.

Nature exploits transition metal centers to enhance and tune the oxidizing power of natural oxidants such as O and HO. The design and interrogation of synthetic metallocomplexes with similar reactivity to metalloproteins provides one strategy for gaining insight into the mechanistic underpinnings of oxygen-activating enzymes such as oxidases, oxygenases, and dioxygenases like Ni-quercetinase (Ni-QueD). Ni-QueD catalyzes the oxidative ring opening of the polyphenol quercetin, a natural product with antioxidant properties.

Copper Induced Radical Dimerization of α-Synuclein Requires Histidine.

Aggregation of the neuronal protein α-synuclein (αS) is a critical factor in the pathogenesis of Parkinson's disease. Analytical methods to detect post-translational modifications of αS are under development, yet the mechanistic underpinnings of biomarkers like dityrosine formation within αS have yet to be established. In our work, we demonstrate that Cu-bound N-terminally acetylated αS (αS) activates O resulting in both intermolecular dityrosine cross-linking within the fibrillar core as well as intramolecular cross-linking within the C-terminal region.

C-Terminal Cu Coordination to α-Synuclein Enhances Aggregation.

The structurally dynamic amyloidogenic protein α-synuclein (αS) is universally recognized as a key player in Parkinson's disease (PD). Copper, which acts as a neuronal signaling agent, is also an effector of αS structure, aggregation, and localization in vivo. In humans, αS is known to carry an acetyl group on the starting methionine residue, capping the N-terminal free amine which was a known high-affinity Cu binding site.

Iron Redox Chemistry Promotes Antiparallel Oligomerization of α-Synuclein.

Brain metal dyshomeostasis and altered structural dynamics of the presynaptic protein α-synuclein (αS) are both implicated in the pathology of Parkinson's disease (PD), yet a mechanistic understanding of disease progression in the context of αS structure and metal interactions remains elusive. In this Communication, we detail the influence of iron, a prevalent redox-active brain biometal, on the aggregation propensity and secondary structure of N-terminally acetylated αS (αS), the physiologically relevant form in humans. We demonstrate that under aerobic conditions, Fe(II) commits αS to a PD-relevant oligomeric assembly, verified by the oligomer-selective A11 antibody, that does not have any parallel β-sheet character but contains a substantial right-twisted antiparallel β-sheet component based on CD analyses and descriptive deconvolution of the secondary structure.

Iron Mesh-Based Metal Organic Framework Filter for Efficient Arsenic Removal.

Efficient oxidation from arsenite [As(III)] to arsenate [As(V)], which is less toxic and more readily to be adsorbed by adsorbents, is important for the remediation of arsenic pollution. In this paper, we report a metal organic framework (MIL-100(Fe)) filter to efficiently remove arsenic from synthetic groundwater. With commercially available iron mesh as a substrate, MIL-100(Fe) is implanted through an in situ growth method.