Aspects of Fe-Incorporation into CaTiO-SrTiO Perovskites and Their Catalytic Application for Ammonia SCO/SCR.

Perovskite materials in the CaTiO-SrTiO system doped with different amounts of iron (1, 2 and 5 mol.%) and various Ca/Sr ratios were prepared by the modified citrate method. Additionally, the materials with 0.

Isolation and crystallization of copper resistance protein B (CopB) from Acinetobacter baumannii.

Acinetobacter baumannii (A. baumannii) is an opportunistic, Gram-negative human pathogen, which is predominantly found in hospital patients. Its antimicrobial resistance is escalating, leading to less efficient treatments, and an increasing interest in identifying new therapeutic drugs.

Cofactor maturase NifEN: A prototype ancient nitrogenase?

Nitrogenase plays a key role in the global nitrogen cycle; yet, the evolutionary history of nitrogenase and, particularly, the sequence of appearance between the homologous, yet distinct NifDK (the catalytic component) and NifEN (the cofactor maturase) of the extant molybdenum nitrogenase, remains elusive. Here, we report the ability of NifEN to reduce N at its surface-exposed L-cluster ([FeSC]), a structural/functional homolog of the M-cluster (or cofactor; [(-homocitrate)MoFeSC]) of NifDK. Furthermore, we demonstrate the ability of the L-cluster-bound NifDK to mimic its NifEN counterpart and enable N reduction.

All That Glitters Is Not Gold: Assessment of Bee Pollen Supplementation Effects on Gastric Mucosa.

The aim of this study was to assess the influence of bee pollen supplementation on the levels of enzymes important for gastric mucosal homeostasis, namely cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and a biomarker-asymmetric dimethylarginine (ADMA)-in the gastric mucosa of Wistar rats. The experimental phase divided the rats into four groups: two control groups, sedentary and active, both not supplemented, and two experimental groups, sedentary and active, supplemented with bee pollen. The results indicated that bee pollen supplementation reduced the levels of COX-1 and elevated iNOS levels, while showing no significant impact on COX-2 levels.

Heterologous expression of a fully active nitrogenase Fe protein in .

The heterologous expression of a fully active Fe protein (AvNifH) has never been accomplished. Given the functional importance of this protein in nitrogenase catalysis and assembly, the successful expression of AvNifH in as reported herein supplies a key element for the further development of heterologous expression systems that explore the catalytic versatility of the Fe protein, either on its own or as a key component of nitrogenase, for nitrogenase-based biotechnological applications in the future. Moreover, the "clean" genetic background of the heterologous expression host allows for an unambiguous assessment of the effect of certain nif-encoded protein factors, such as AvNifM described in this work, in the maturation of AvNifH, highlighting the utility of this heterologous expression system in further advancing our understanding of the complex biosynthetic mechanism of nitrogenase.

Heterologous synthesis of the complex homometallic cores of nitrogenase P- and M-clusters in .

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 is to generate the complex metalloclusters (P- and M-clusters) within this enzyme, which involves some highly unique bioinorganic chemistry/metalloenzyme biochemistry that is not generally dealt with in the heterologous expression of proteins via synthetic biology; in particular, the heterologous synthesis of the homometallic P-cluster ([FeS]) and M-cluster core (or L-cluster; [FeSC]) on their respective protein scaffolds, which represents two crucial checkpoints along the biosynthetic pathway of a complete nitrogenase, has yet to be demonstrated by biochemical and spectroscopic analyses of purified metalloproteins. Here, we report the heterologous formation of a P-cluster-containing NifDK protein upon coexpression of , , , and genes, and that of an L-cluster-containing NifB protein upon coexpression of , and genes alongside the gene, in .

The Effect of Al and Ti Additions on Solid Solution Strengthening and Precipitation Hardening in CoNiFe Medium-Entropy Alloys.

The effect of Al and Ti additions on the microstructure and properties of CoNiFe alloys was studied in this paper. The investigations were conducted on four specially designed and produced arc furnace alloys (from 3 to 5 components, with medium to high entropy). Samples in various states were analyzed, i.

Principles to recover copper-conducting CTR proteins for the purpose of structural and functional studies.

Transition metals such as copper and zinc are essential elements required for the survival of most organisms, from bacteria to humans. Yet, elevated levels of these elements are highly toxic. The Copper TRansporter protein family (CTRs) represents the only identified copper uptake proteins in eukaryotes and hence serves as key components for the maintenance of appropriate levels of the metal.

A novel approach for measuring membrane permeability for organic compounds via surface plasmon resonance detection.

Well-known methods for measuring permeability of membranes include static or flow diffusion chambers. When studying the effects of organic compounds on plants, the use of such model systems allows to investigate xenobiotic behavior at the cuticular barrier level and obtain an understanding of the initial penetration processes of these substances into plant leaves. However, the use of diffusion chambers has disadvantages, including being time-consuming, requiring sampling, or a sufficiently large membrane area, which cannot be obtained from all types of plants.

Nitrogenase Fe Protein: A Multi-Tasking Player in Substrate Reduction and Metallocluster Assembly.

The Fe protein of nitrogenase plays multiple roles in substrate reduction and metallocluster assembly. Best known for its function to transfer electrons to its catalytic partner during nitrogenase catalysis, the Fe protein is also a key player in the biosynthesis of the complex metalloclusters of nitrogenase. In addition, it can function as a reductase on its own and affect the ambient reduction of CO or CO to hydrocarbons.

Microfluidic-Derived Detection of Protein-Facilitated Copper Flux Across Lipid Membranes.

Measurement of protein-facilitated copper flux across biological membranes is a considerable challenge. Here, we demonstrate a straightforward microfluidic-derived approach for visualization and measurement of membranous Cu flux. Giant unilamellar vesicles, reconstituted with the membrane protein of interest, are prepared, surface-immobilized, and assessed using a novel quencher-sensor reporter system for detection of copper.

PcoB is a defense outer membrane protein that facilitates cellular uptake of copper.

Copper (Cu) is one of the most abundant trace metals in all organisms, involved in a plethora of cellular processes. Yet elevated concentrations of the element are harmful, and interestingly prokaryotes are more sensitive for environmental Cu stress than humans. Various transport systems are present to maintain intracellular Cu homeostasis, including the prokaryotic plasmid-encoded multiprotein pco operon, which is generally assigned as a defense mechanism against elevated Cu concentrations.

Catalytic Oxidation of Ammonia over Cerium-Modified Copper Aluminium Zinc Mixed Oxides.

Copper-containing mixed metal oxides are one of the most promising catalysts of selective catalytic oxidation of ammonia. These materials are characterized by high catalytic efficiency; however, process selectivity to dinitrogen is still an open challenge. The set of Cu-Zn-Al-O and Ce/Cu-Zn-Al-O mixed metal oxides were tested as catalysts of selective catalytic oxidation of ammonia.

The role of guanidine hydrochloride in graphitic carbon nitride synthesis.

Graphitic carbon nitride (CN) was synthesized from guanidine hydrochloride (G), melamine (M) and dicyandiamide (DCDA). The CN materials synthetized from the pure precursors and their mixtures were characterized by common methods, including thermal analysis, and their photocatalytic activities were tested by the degradation of selected organic pollutants, such as amoxicillin, phenol, Rhodamine B (RhB). Remarkable changes in their texture properties in terms of particle sizes, specific surface areas (SSA) and consequently their photocatalytic activity were explained by the role of guanidine hydrochloride in their synthesis.

Phylogenetic analysis reveals an ancient gene duplication as the origin of the MdtABC efflux pump.

The efflux pumps from the Resistance-Nodulation-Division family, RND, are main contributors to intrinsic antibiotic resistance in Gram-negative bacteria. Among this family, the MdtABC pump is unusual by having two inner membrane components. The two components, MdtB and MdtC are homologs, therefore it is evident that the two components arose by gene duplication.

Electrophoretic deposition of organic/inorganic composite coatings containing ZnO nanoparticles exhibiting antibacterial properties.

To address one of the serious problems associated with permanent implants, namely bacterial infections, novel organic/inorganic coatings containing zinc oxide nanoparticles (nZnO) are proposed. Coatings were obtained by electrophoretic deposition (EPD) on stainless steel 316L. Different deposition conditions namely: deposition times in the range 60-300s and applied voltage in the range 5-30V as well as developing a layered coating approach were studied.

Functional Differentiation of Antiporter-Like Polypeptides in Complex I; a Site-Directed Mutagenesis Study of Residues Conserved in MrpA and NuoL but Not in MrpD, NuoM, and NuoN.

It has long been known that the three largest subunits in the membrane domain (NuoL, NuoM and NuoN) of complex I are homologous to each other, as well as to two subunits (MrpA and MrpD) from a Na+/H+ antiporter, Mrp. MrpA and NuoL are more similar to each other and the same is true for MrpD and NuoN. This suggests a functional differentiation which was proven experimentally in a deletion strain model system, where NuoL could restore the loss of MrpA, but not that of MrpD and vice versa.

The Na+ transport in gram-positive bacteria defect in the Mrp antiporter complex measured with 23Na nuclear magnetic resonance.

(23)Na nuclear magnetic resonance (NMR) has previously been used to monitor Na(+) translocation across membranes in gram-negative bacteria and in various other organelles and liposomes using a membrane-impermeable shift reagent to resolve the signals resulting from internal and external Na(+). In this work, the (23)Na NMR method was adapted for measurements of internal Na(+) concentration in the gram-positive bacterium Bacillus subtilis, with the aim of assessing the Na(+) translocation activity of the Mrp (multiple resistance and pH) antiporter complex, a member of the cation proton antiporter-3 (CPA-3) family. The sodium-sensitive growth phenotype observed in a B.

Functional role of the MrpA- and MrpD-homologous protein subunits in enzyme complexes evolutionary related to respiratory chain complex I.

NADH:quinone oxidoreductase or complex I is a large membrane bound enzyme complex that has evolved from the combination of smaller functional building blocks. Intermediate size enzyme complexes exist in nature that comprise some, but not all of the protein subunits in full size 14-subunit complex I. The membrane spanning complex I subunits NuoL, NuoM and NuoN are homologous to each other and to two proteins from one particular class of Na(+)/H(+) antiporters, denoted MrpA and MrpD.

Structure and function of the C-terminal domain of MrpA in the Bacillus subtilis Mrp-antiporter complex--the evolutionary progenitor of the long horizontal helix in complex I.

MrpA and MrpD are homologous to NuoL, NuoM and NuoN in complex I over the first 14 transmembrane helices. In this work, the C-terminal domain of MrpA, outside this conserved area, was investigated. The transmembrane orientation was found to correspond to that of NuoJ in complex I.

Electrochemical communication between heterotrophically grown Rhodobacter capsulatus with electrodes mediated by an osmium redox polymer.

The metabolically versatile purple bacteria Rhodobacter capsulatus was investigated to check its possible applicability in biofuel cells and electrochemical microbial biosensors. The wild type strain ATCC 17015 and mutant strain 37b4 lacking the lipopolysaccharide capsule was compared for their ability to communicate with electrodes modified with an osmium redox polymer. In this work, aerobic heterotrophically grown R.

A cytochrome c fusion protein domain for convenient detection, quantification, and enhanced production of membrane proteins in Escherichia coli--expression and characterization of cytochrome-tagged Complex I subunits.

Overproduction of membrane proteins can be a cumbersome task, particularly if high yields are desirable. NADH:quinone oxidoreductase (Complex I) contains several very large membrane-spanning protein subunits that hitherto have been impossible to express individually in any appreciable amounts in Escherichia coli. The polypeptides contain no prosthetic groups and are poorly antigenic, making optimization of protein production a challenging task.

Precise detection of pH inside large unilamellar vesicles using membrane-impermeable dendritic porphyrin-based nanoprobes.

Accurate real-time measurements of proton concentration gradients are pivotal to mechanistic studies of proton translocation by membrane-bound enzymes. Here we report a detailed characterization of the pH-sensitive fluorescent nanoprobe Glu(3), which is well suited for pH measurements in microcompartmentalized biological systems. The probe is a polyglutamic porphyrin dendrimer in which multiple carboxylate termini ensure its high water solubility and prevent its diffusion across phospholipid membranes.