Electrosynthesis of mussel-inspired adhesive polymers as a novel class of transient enzyme stabilizers.

Multifunctional ortho-quinones are required for the formation of thiol-catechol-connectivities (TCC) but can be delicate to handle. We present the electrochemical oxidation of the dipeptide DiDOPA, achieving up to 92% conversion efficiency of the catechols to ortho-quinones. Graphite and stainless steel could be employed as cost-efficient electrodes.

Tyrosinases: a family of copper-containing metalloenzymes.

Tyrosinases (TYRs) are a family of copper-containing metalloenzymes that are present in all domains of life. TYRs catalyze the reactions that start the biosynthesis of melanin, the main pigment of the animal kingdom, and are also involved in the formation of the bright colors seen on the caps of mushrooms and in the petals of flowers. TYRs catalyze the -hydroxylation and oxidation of phenols and the oxidation of catechols to the respective -quinones.

Unveiling the agonistic properties of Preyssler-type Polyoxotungstates on purinergic P2 receptors.

The Preyssler-type polyoxotungstate ({PW}) belongs to the family of polyanionic metal-oxides formed by group V and VI metal ions, such as V, Mo and W, commonly known as polyoxometalates (POMs). POMs have demonstrated inhibitory effect on a significant number of ATP-binding proteins in vitro. Purinergic P2 receptors, widely expressed in eukaryotic cells, contain extracellularly oriented ATP-binding sites and play many biological roles with health implications.

Insights into the early-life chemical exposome of Nigerian infants and potential correlations with the developing gut microbiome.

Early-life exposure to natural and synthetic chemicals can impact acute and chronic health conditions. Here, a suspect screening workflow anchored on high-resolution mass spectrometry was applied to elucidate xenobiotics in breast milk and matching stool samples collected from Nigerian mother-infant pairs (n = 11) at three time points. Potential correlations between xenobiotic exposure and the developing gut microbiome, as determined by 16S rRNA gene amplicon sequencing, were subsequently explored.

Mushroom Tyrosinase: Six Isoenzymes Catalyzing Distinct Reactions.

"Mushroom tyrosinase" from the common button mushroom is the most frequently used source of tyrosinase activity, both for basic and applied research. Here, the complete tyrosinase family from Agaricus bisporus var. bisporus (abPPO1-6) was cloned from mRNA and expressed heterologously using a single protocol.

Extraction, Purification, and Characterization of Olive ( L., cv. Chemlal) Polyphenol Oxidase.

Among fruits susceptible to enzymatic browning, olive polyphenol oxidase (PPO) stood out as being unisolated from a natural source until this study, wherein we successfully purified and characterized the enzyme. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of heated and nonheated PPO revealed distinct molecular weights of 35 and 54 kDa, respectively, indicative of its oligomeric nature comprising active and C-terminal subunits. PPO displayed latency, fully activating with 5 mM SDS under optimal conditions of pH 7.

All-Inorganic Polyoxometalates Act as Superchaotropic Membrane Carriers.

Polyoxometalates (POMs) are known antitumoral, antibacterial, antiviral, and anticancer agents and considered as next-generation metallodrugs. Herein, a new biological functionality in neutral physiological media, where selected mixed-metal POMs are sufficiently stable and able to affect membrane transport of impermeable, hydrophilic, and cationic peptides (heptaarginine, heptalysine, protamine, and polyarginine) is reported. The uptake is observed in both, model membranes as well as cells, and attributed to the superchaotropic properties of the polyoxoanions.

Heterotrophy among Cyanobacteria.

Cyanobacteria have been studied in recent decades to investigate the principle mechanisms of plant-type oxygenic photosynthesis, as they are the inventors of this process, and their cultivation and research is much easier compared to land plants. Nevertheless, many cyanobacterial strains possess the capacity for at least some forms of heterotrophic growth. This review demonstrates that cyanobacteria are much more than simple photoautotrophs, and their flexibility toward different environmental conditions has been underestimated in the past.

Biochemical Investigations of Five Recombinantly Expressed Tyrosinases Reveal Two Novel Mechanisms Impacting Carbon Storage in Wetland Ecosystems.

Wetlands are globally distributed ecosystems characterized by predominantly anoxic soils, resulting from water-logging. Over the past millennia, low decomposition rates of organic matter led to the accumulation of 20-30% of the world's soil carbon pool in wetlands. Phenolic compounds are critically involved in stabilizing wetland carbon stores as they act as broad-scale inhibitors of hydrolytic enzymes.

Exposomic Biomonitoring of Polyphenols by Non-Targeted Analysis and Suspect Screening.

Polyphenols, prevalent in plants and fungi, are investigated intensively in nutritional and clinical settings because of their beneficial bioactive properties. Due to their complexity, analysis with untargeted approaches is favorable, which typically use high-resolution mass spectrometry (HRMS) rather than low-resolution mass spectrometry (LRMS). Here, the advantages of HRMS were evaluated by thoroughly testing untargeted techniques and available online resources.

Speciation atlas of polyoxometalates in aqueous solutions.

Speciation is the key parameter in solution chemistry that describes the composition, concentration, and oxidation state of each chemical form of an element present in a sample. The speciation study of complex polyatomic ions has remained challenging because of the large number of factors affecting stability and the limited number of direct methods. To address these challenges, we developed the speciation atlas of 10 polyoxometalates commonly used in catalytic and biological applications in aqueous solutions, where the speciation atlas provides both a species distribution database and a predictive model for other polyoxometalates to be used.

Synthesis, Characterization, and Antibacterial Activity of Ni-Substituted Krebs-type Sandwich-Tungstobismuthates Functionalized with Amino Acids.

Four new Ni-substituted Krebs-type sandwich-tungstobismuthates, KNi[{Ni(β-ala)(HO)}{Ni(HO)}{Ni(HO)(η-β-ala)}(-β-BiWO)]·49HO , KNa[{Ni(η-L-asp)}(WO)(-β-BiWO)]·36HO·L-asp , KNa[{Ni(gly)(HO)}(WO)(-β-BiWO)]·86HO and KNa[{Ni(η-serinol) (HO)}{Ni(HO)}(-β-BiWO)]·42HO have been synthesized by one-pot solution methods. All compounds have been characterized in the solid state by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), elemental and thermogravimetric analyses, and infrared spectroscopy (IR), as well as by UV-vis spectroscopy in solution. The antibacterial activity of all compounds was studied against four bacterial strains by the determination of the minimum inhibitory concentration (MIC).

Immobilization of Agaricus bisporus Polyphenol Oxidase 4 on mesoporous silica: Towards mimicking key enzymatic processes in peat soils.

Hypothesis: The use of immobilized enzyme-type biocatalysts to mimic specific processes in soil can be considered one of the most promising alternatives to overcome the difficulties behind the structural elucidation of riverine humic-derived iron-complexes. Herein, we propose that the immobilization of the functional mushroom tyrosinase, Agaricus bisporus Polyphenol Oxidase 4 (AbPPO4) on mesoporous SBA-15-type silica could contribute to the study of small aquatic humic ligands such as phenols.

Experiments: The silica support was functionalized with amino-groups in order to investigate the impact of surface charge on the tyrosinase loading efficiency as well as on the catalytic performance of adsorbed AbPPO4.

Ni tetracubane cores with slow relaxation of magnetization and efficient charge utilization for photocatalytic hydrogen evolution.

We report two Ni multicubane topologies enclosed in the polyanions [Ni(OH)(WO)(PO)(B-α-PWO)]{NiW} and [Ni(OH)(HPO)(PO)(B-α-PWO)(A-α-PWO)]{NiW} that magnetically behave as Ni units clearly distinguishing them from typical Ni cubanes as shown by magnetic studies together with high field and frequency electron paramagnetic resonance (HFEPR). Beyond the unprecedented static properties, {NiW} shows the unusual coexistence of slow relaxation of the magnetization and a diamagnetic ground state ( = 0), providing the unique opportunity of studying the essentially elusive magnetic relaxation behavior in excited states. The cubane-topology dependent activity of {NiW} and {NiW} as homogeneous HER photocatalysts unveils the structural key features significant for the design of photocatalysts with efficient charge utilization exemplified by high quantum yields (QY) of 10.

Oxo-Replaced Polyoxometalates: There Is More than Oxygen.

The presence of oxo-ligands is one of the main required characteristics for polyoxometalates (POMs), although some oxygen ions in a metallic environment can be replaced by other nonmetals, while maintaining the POM structure. The replacement of oxo-ligands offers a valuable approach to tune the charge distribution and connected properties like reducibility and hydrolytic stability of POMs for the development of tailored compounds. By assessing the reported catalytic and biological applications and connecting them to POM structures, the present review provides a guideline for synthetic approaches and aims to stimulate further applications where the oxo-replaced compounds are superior to their oxo-analogues.

Biochemical characterization of Dimocarpus longan polyphenol oxidase provides insights into its catalytic efficiency.

The "dragon-eye" fruits produced by the tropical longan tree are rich in nutrients and antioxidants. They suffer from post-harvest enzymatic browning, a process for which mainly the polyphenol oxidase (PPO) family of enzymes is responsible. In this study, two cDNAs encoding the PPO have been cloned from leaves of Dimocarpus longan (Dl), heterologously expressed in Escherichia coli and purified by affinity chromatography.

The Preyssler-Type Polyoxotungstate Exhibits Anti-Quorum Sensing, Antibiofilm, and Antiviral Activities.

The increase in bacterial resistance to antibiotics has led researchers to find new compounds or find combinations between different compounds with potential antibacterial action and with the ability to prevent the development of antibiotic resistance. Polyoxotungstates (POTs) are inorganic clusters that may fulfill that need, either individually or in combination with antibiotics. Herein, we report the ability of the polyoxotungstates (POTs) with Wells-Dawson P2W18, P2W17, P2W15, and Preyssler P5W30 type structures to differently affect Gram-negative and Gram-positive microorganisms, either susceptible or resistant to antibiotics.

Inhibition of SERCA and PMCA Ca-ATPase activities by polyoxotungstates.

Plasma membrane calcium ATPases (PMCA) and sarco(endo) reticulum calcium ATPases (SERCA) are key proteins in the maintenance of calcium homeostasis. Herein, we compare for the first time the inhibition of SERCA and PMCA calcium pumps by several polyoxotungstates (POTs), namely by Wells-Dawson phosphotungstate anions [PWO] (intact, {PW}), [PWO] (monolacunary, {PW}), [PWO] (trilacunary, {PW}), [HPWO] (hexalacunary, {PW}), [HPWVO] (trivanadium-substituted, {PWV}) and by Preyssler-type anion [NaPWO] ({PW}). The speciation in the solutions of tested POTs was investigated by P and V NMR spectroscopy.

The Novel Role of Tyrosinase Enzymes in the Storage of Globally Significant Amounts of Carbon in Wetland Ecosystems.

Over the last millennia, wetlands have been sequestering carbon from the atmosphere via photosynthesis at a higher rate than releasing it and, therefore, have globally accumulated 550 × 10 g of carbon, which is equivalent to 73% of the atmospheric carbon pool. The accumulation of organic carbon in wetlands is effectuated by phenolic compounds, which suppress the degradation of soil organic matter by inhibiting the activity of organic-matter-degrading enzymes. The enzymatic removal of phenolic compounds by bacterial tyrosinases has historically been blocked by anoxic conditions in wetland soils, resulting from waterlogging.

Immobilization of a [CoCo(HO)WO] Polyoxoanion for the Photocatalytic Oxygen Evolution Reaction.

The ongoing transition to renewable energy sources and the implementation of artificial photosynthetic setups call for an efficient and stable water oxidation catalyst (WOC). Here, we heterogenize a molecular all-inorganic [CoCo(HO)WO] ({CoCoW}) Keggin-type polyoxometalate (POM) onto a model TiO surface, employing a 3-aminopropyltriethoxysilane (APTES) linker to form a novel heterogeneous photosystem for light-driven water oxidation. The {CoCoW}-APTES-TiO hybrid is characterized using a set of spectroscopic and microscopic techniques to reveal the POM integrity and dispersion to elucidate the POM/APTES and APTES/TiO binding modes as well as to visualize the attachment of individual clusters.

Trisubstituted 4f- and 4d tungstoantimonates as artificial phosphoesterases for nerve agent degradation.

Three new trisubstituted 4f- and 4d tungstoantimonates (TA) KNa[(M(CHCOO))(HPO)(WO)(SbWO)]·HO {M3(HPO3)Sb3W28} (M = Gd, Y, Yb, = 35-36) were synthesized using a double-template synthetic approach. Following their characterization in the solid state employing single- and powder X-ray diffraction (XRD), IR-spectroscopy, and elemental - and thermogravimetric analyses (TGA), {M3(HPO3)Sb3W28} were subjected to a comprehensive set of solution characterization methods including UV/vis- and multinuclear P and C NMR spectroscopy. All representatives were shown to be highly active, recyclable, and stable Lewis-acid catalysts towards the nerve agent simulant ,-dimethyl -(4-nitrophenyl) phosphate (DMNP) at neutral pH (in Tris-HCl [125 mM] at pD 7.

Lanthanides Singing the Blues: Their Fascinating Role in the Assembly of Gigantic Molybdenum Blue Wheels.

Molybdenum blues (MBs) are a distinct class of polyoxometalates, exhibiting versatile/impressive architectures and high structural flexibility. In acidified and reduced aqueous environments, isopolymolybdates generate precisely organizable building blocks, which enable unique nanoscopic molecular systems (MBs) to be constructed and further fine-tuned by hetero elements such as lanthanide (Ln) ions. This Review discusses wheel-shaped MB-based structure types with strong emphasis on the ∼30 Ln-containing MBs as of August 2021, which include both organically hybridized and nonhybridized structures synthesized to date.

Quantifying up to 90 polyphenols simultaneously in human bio-fluids by LC-MS/MS.

Establishing a method for human biomonitoring (HBM) of polyphenols enables the assessment of internal concentrations of these food bio-actives and the correlation with potential health effects such as antioxidant or anti-inflammatory properties. Thus, a targeted LC-MS/MS method for quantifying up to 90 analytes, representing the main polyphenol classes including flavanones, isoflavones, stilbenes, and phenolic acids, was developed for human urine, serum, and plasma. The method was established for low sample volumes and with a cost and time efficient sample preparation protocol for high-throughput, which is critical for its application in large cohort and exposome-wide association studies.