-
Marine Pollution Bulletin Nov 2023Queensland loggerhead turtle nest numbers at Mon Repos (MR) indicate population recovery that doesn't occur at Wreck Island (WI). Previous research illustrated that MR...
Queensland loggerhead turtle nest numbers at Mon Repos (MR) indicate population recovery that doesn't occur at Wreck Island (WI). Previous research illustrated that MR and WI turtles forage in different locations, potentially indicating risks differences. Blood, scute, and egg were collected from turtles nesting at MR and WI, with known foraging sites (from concurrent studies). Trace element and organic contaminants were assessed via acid digestion and in vitro cytotoxicity bioassays, respectively. WI turtles had significantly higher scute uranium and blood molybdenum compared to MR turtles, and arsenic was higher in WI turtles foraging north and MR turtles foraging south. Egg and blood titanium, manganese, cadmium, barium, lead, and molybdenum, and scute and egg selenium and mercury significantly correlated. Blood (75 %) extracts produced significant toxicity in vitro in turtle fibroblast cells. In conclusion, reducing chemical exposure at higher risk foraging sites would likely benefit sea turtles and their offspring.
Topics: Animals; Turtles; Molybdenum; Trace Elements; Selenium; Queensland; Nesting Behavior
PubMed: 37844482
DOI: 10.1016/j.marpolbul.2023.115605 -
Redox Report : Communications in Free... Jan 2017This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information... (Review)
Review
OBJECTIVES
This review summarizes the spectroscopic results, which will provide useful suggestions for future research. In addition, the fields that urgently need more information are also advised.
BACKGROUND
Nitrite-NO-cGMP has been considered as an important signaling pathway of NO in human cells. To date, all the four known human molybdenum-containing enzymes, xanthine oxidase, aldehyde oxidase, sulfite oxidase, and mitochondrial amidoxime-reducing component, have been shown to function as nitrite reductases under hypoxia by biochemical, cellular, or animal studies. Various spectroscopic techniques have been applied to investigate the structure and catalytic mechanism of these enzymes for more than 20 years.
METHODS
We summarize the published data on the applications of UV-vis and EPR spectroscopies, and X-ray crystallography in studying nitrite reductase activity of the four human molybdenum-containing enzymes.
RESULTS
UV-vis has provided useful information on the redox active centers of these enzymes. The utilization of EPR spectroscopy has been critical in determining the coordination and redox status of the Mo center during catalysis. Despite the lack of substrate-bound crystal structures of these nitrite reductases, valuable structural information has been obtained by X-ray crystallography.
CONCLUSIONS
To fully understand the catalytic mechanisms of these physiologically/pathologically important nitrite reductases, structural studies on substrate-redox center interaction are needed.
Topics: Animals; Humans; Molybdenum; Nitric Oxide; Nitrite Reductases; Oxidation-Reduction
PubMed: 27686142
DOI: 10.1080/13510002.2016.1206175 -
Ecotoxicology and Environmental Safety Dec 2022Chromium (Cr) is a harmful heavy metal that poses a serious threat to plants and animals. Selenium (Se) and molybdenum (Mo) are two beneficial elements for plant growth...
Chromium (Cr) is a harmful heavy metal that poses a serious threat to plants and animals. Selenium (Se) and molybdenum (Mo) are two beneficial elements for plant growth and resistance. However, their interactive effects on Cr uptake and distribution are poorly understood. Therefore, a hydroponics experiment was conducted to explore the effects of the use of Se and Mo alone and simultaneously on mitigating Cr toxicity. In this study, Nicotiana tabacum L. seedlings were exposed to control, 50 µM Cr, 50 μM Cr + 2 μM Se, 50 μM Cr + 1 μM Mo, or 50 μM Cr + 2 μM Se + 1 μM Mo in Hoagland solution. After 2 weeks, the plant biomass, Cr, Se and Mo contents, photosynthesis, leaf ultrastructure, antioxidant system, subcellular distribution and associated gene expression in Nicotiana tabacum L. were determined. The results showed that simultaneous use of Se and Mo promoted tobacco growth under Cr stress, as evidenced by reducing reactive oxygen species (ROS) content and reducing Cr translocation factor (TF) and inducing a 51.3% reduction in Cr content in shoots. Additionally, Se-Mo interactions increased the levels of glutathione (GSH) and phytochelatin (PC) and the distribution of Cr in the cell walls and organelles. Furthermore, the relative expression of PCS1 was upregulated, while those of NtST1 and MSN1 were downregulated. The results concluded that the simultaneous use of Se and Mo effectively alleviated Cr toxicity in Nicotiana tabacum L., which not only offers an efficient way for crops to resist Cr toxicity but also provides evidence for the benefit of Se combined with Mo.
Topics: Animals; Selenium; Molybdenum; Nicotiana; Chromium; Biological Transport; Glutathione
PubMed: 36455352
DOI: 10.1016/j.ecoenv.2022.114312 -
Acta Biomaterialia Apr 2024Cardiac pacing with temporary epicardial pacing wires (TEPW) is used to treat rhythm disturbances after cardiac surgery. Occasionally, TEPW cannot be mechanically...
Cardiac pacing with temporary epicardial pacing wires (TEPW) is used to treat rhythm disturbances after cardiac surgery. Occasionally, TEPW cannot be mechanically extracted and remain in the thorax, where they may rarely cause serious complications like migration and infection. We aim to develop bioresorbable TEPW that will dissolve over time even if postoperative removal is unsuccessful. In the present study, we demonstrate a completely bioresorbable design using molybdenum (Mo) as electric conductor and the resorbable polymers poly(D, L-lactic-co-glycolic acid) (PLGA) and polycaprolactone (PCL) for electrically insulating double-coating. We compared the pacing properties of these Mo TEPW demonstrators to conventional steel TEPW in Langendorff-perfused rat hearts and observed similar functionality. In vitro, static immersion tests in simulated body fluid for up to 28 days elucidated the degradation behaviour of uncoated Mo strands and the influence of polymer coating thereon. Degradation was considerably reduced in double-coated Mo TEPW compared to the uncoated and the PLGA-coated condition. Furthermore, we confirmed good biocompatibility of Mo degradation products in the form of low cytotoxicity in cell cultures of human cardiomyocytes and cardiac fibroblasts. STATEMENT OF SIGNIFICANCE: Temporary pacing wires are routinely implanted on the heart surface to treat rhythm disturbances in the days following cardiac surgery. Subsequently, these wires are to be removed. When removal attempts are unsuccessful, wires are cut at skin level and the remainders are left inside the chest. Retained fragments may migrate within the body or become a centre of infection. These complications may be prevented using resorbable pacing wires. We manufactured completely resorbable temporary pacing wires using molybdenum as electrical conductor and assessed their function, degradation and biological compatibility. Our study represents an important step in the development of a safer approach to the treatment of rhythm disturbances after cardiac surgery.
Topics: Humans; Animals; Rats; Cardiac Pacing, Artificial; Pacemaker, Artificial; Molybdenum; Absorbable Implants; Pericardium
PubMed: 38432350
DOI: 10.1016/j.actbio.2024.02.039 -
Molecules (Basel, Switzerland) Oct 2023Sulfite oxidase is one of five molybdenum-containing enzymes known in eukaryotes where it catalyzes the oxidation of sulfite to sulfate. This review covers the history... (Review)
Review
Sulfite oxidase is one of five molybdenum-containing enzymes known in eukaryotes where it catalyzes the oxidation of sulfite to sulfate. This review covers the history of sulfite oxidase research starting out with the early years of its discovery as a hepatic mitochondrial enzyme in vertebrates, leading to basic biochemical and structural properties that have inspired research for decades. A personal view on sulfite oxidase in plants, that sulfates are assimilated for their de novo synthesis of cysteine, is presented by Ralf Mendel with numerous unexpected findings and unique properties of this single-cofactor sulfite oxidase localized to peroxisomes. Guenter Schwarz connects his research to sulfite oxidase via its deficiency in humans, demonstrating its unique role amongst all molybdenum enzymes in humans. In essence, in both the plant and animal kingdoms, sulfite oxidase represents an important player in redox regulation, signaling and metabolism, thereby connecting sulfur and nitrogen metabolism in multiple ways.
Topics: Animals; Humans; Sulfite Oxidase; Molybdenum; Sulfites; Plants; Molybdenum Cofactors; Sulfates
PubMed: 37836841
DOI: 10.3390/molecules28196998 -
Molecules (Basel, Switzerland) Aug 2023Molybdenum-containing enzymes of the xanthine oxidase (XO) family are well known to catalyse oxygen atom transfer reactions, with the great majority of the characterised... (Review)
Review
Molybdenum-containing enzymes of the xanthine oxidase (XO) family are well known to catalyse oxygen atom transfer reactions, with the great majority of the characterised enzymes catalysing the insertion of an oxygen atom into the substrate. Although some family members are known to catalyse the "reverse" reaction, the capability to abstract an oxygen atom from the substrate molecule is not generally recognised for these enzymes. Hence, it was with surprise and scepticism that the "molybdenum community" noticed the reports on the mammalian XO capability to catalyse the oxygen atom abstraction of nitrite to form nitric oxide (NO). The lack of precedent for a molybdenum- (or tungsten) containing nitrite reductase on the nitrogen biogeochemical cycle contributed also to the scepticism. It took several kinetic, spectroscopic and mechanistic studies on enzymes of the XO family and also of sulfite oxidase and DMSO reductase families to finally have wide recognition of the molybdoenzymes' ability to form NO from nitrite. Herein, integrated in a collection of "personal views" edited by Professor Ralf Mendel, is an overview of my personal journey on the XO and aldehyde oxidase-catalysed nitrite reduction to NO. The main research findings and the path followed to establish XO and AO as competent nitrite reductases are reviewed. The evidence suggesting that these enzymes are probable players of the mammalian NO metabolism is also discussed.
Topics: Animals; Mammals; Molybdenum; Nitric Oxide; Nitrite Reductases; Nitrites; Oxidation-Reduction; Oxygen; Xanthine Oxidase
PubMed: 37570788
DOI: 10.3390/molecules28155819 -
Angewandte Chemie (International Ed. in... Oct 2022The biological process of dinitrogen reduction to ammonium occurs at the cofactors of nitrogenases, the only enzymes that catalyze this challenging chemical reaction....
The biological process of dinitrogen reduction to ammonium occurs at the cofactors of nitrogenases, the only enzymes that catalyze this challenging chemical reaction. Three types of nitrogenases have been described, named according to the heterometal in their cofactor: molybdenum, vanadium or iron nitrogenases. Spectroscopic and structural characterization allowed the unambiguous identification of the cofactors of molybdenum and vanadium nitrogenases and revealed a central μ -carbide in both of them. Although genetic studies suggested that the cofactor of the iron nitrogenase contains a similar Fe C core, this has not been experimentally demonstrated. Here we report Valence-to-Core X-ray Emission Spectroscopy providing experimental evidence that this cofactor contains a carbide, thereby making the Fe C core a feature of all nitrogenase cofactors.
Topics: Ammonium Compounds; Iron; Molybdenum; Nitrogenase; Oxidation-Reduction; Vanadium
PubMed: 35975943
DOI: 10.1002/anie.202209190 -
Angewandte Chemie (International Ed. in... Mar 2019Polyoxometalates (POMs) are an emerging class of inorganic metal oxides, which over the last decades demonstrated promising biological activities by the virtue of their... (Review)
Review
Polyoxometalates (POMs) are an emerging class of inorganic metal oxides, which over the last decades demonstrated promising biological activities by the virtue of their great diversity in structures and properties. They possess high potential for the inhibition of various tumor types; however, their unspecific interactions with biomolecules and toxicity impede their clinical usage. The current focus of the field of biologically active POMs lies on organically functionalized and POM-based nanocomposite structures as these hybrids show enhanced anticancer activity and significantly reduced toxicity towards normal cells in comparison to unmodified POMs. Although the antitumor activity of POMs is well documented, their mechanisms of action are still not well understood. In this Review, an overview is given of the cytotoxic effects of POMs with a special focus on POM-based hybrid and nanocomposite structures. Furthermore, we aim to provide proposed mode of actions and to identify molecular targets. POMs are expected to develop into the next generation of anticancer drugs that selectively target cancer cells while sparing healthy cells.
Topics: Animals; Antineoplastic Agents; Drug Discovery; Humans; Models, Molecular; Molybdenum; Neoplasms; Niobium; Organometallic Compounds; Tungsten; Tungsten Compounds; Vanadium
PubMed: 29893459
DOI: 10.1002/anie.201803868 -
Biochimica Et Biophysica Acta Jun 2015The biosynthesis of the molybdenum cofactor (Moco) has been intensively studied, in addition to its insertion into molybdoenzymes. In particular, a link between the... (Review)
Review
The biosynthesis of the molybdenum cofactor (Moco) has been intensively studied, in addition to its insertion into molybdoenzymes. In particular, a link between the assembly of molybdoenzymes and the biosynthesis of FeS clusters has been identified in the recent years: 1) the synthesis of the first intermediate in Moco biosynthesis requires an FeS-cluster containing protein, 2) the sulfurtransferase for the dithiolene group in Moco is also involved in the synthesis of FeS clusters, thiamin and thiolated tRNAs, 3) the addition of a sulfido-ligand to the molybdenum atom in the active site additionally involves a sulfurtransferase, and 4) most molybdoenzymes in bacteria require FeS clusters as redox active cofactors. In this review we will focus on the biosynthesis of the molybdenum cofactor in bacteria, its modification and insertion into molybdoenzymes, with an emphasis to its link to FeS cluster biosynthesis and sulfur transfer.
Topics: Bacteria; Bacterial Proteins; Coenzymes; Iron-Sulfur Proteins; Metalloproteins; Models, Biological; Models, Chemical; Molecular Structure; Molybdenum; Molybdenum Cofactors; Oxidoreductases; Pteridines
PubMed: 25268953
DOI: 10.1016/j.bbamcr.2014.09.021 -
Journal of Inorganic Biochemistry Mar 2023The rational design and functionalization of small, simple, and stable peptides scaffolds is an attractive avenue to mimic catalytic metal-centres of complex proteins,...
The rational design and functionalization of small, simple, and stable peptides scaffolds is an attractive avenue to mimic catalytic metal-centres of complex proteins, relevant for the design of metalloenzymes with environmental, biotechnological and health impacts. The de novo designed αDIV-L21C framework has a rubredoxin-like metal binding site and was used in this work to incorporate a Mo-atom. Thermostability studies using differential scanning calorimetry showed an increase of 4 °C in the melting temperature of the Mo-αDIV-L21C when compared to the apo-αDIV-L21C. Circular dichroism in the visible and far-UV regions corroborated these results showing that Mo incorporation provides stability to the peptide even though there were almost no differences observed in the secondary structure. A formal reduction potential of ∼ -408 mV vs. NHE, pH 7.6 was determined. Combining electrochemical results, EPR and UV-visible data we discuss the oxidation state of the molybdenum centre in Mo-αDIV-L21C and propose that is mainly in a Mo (VI) oxidation state.
Topics: Molybdenum; Rubredoxins; Metalloproteins; Oxidation-Reduction; Peptides
PubMed: 36603242
DOI: 10.1016/j.jinorgbio.2022.112096