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A hybrid receptor‐sensor for anions originating from the merging of positively charged ammonium moieties for electrostatic attraction/stronger binding of azacrowns with directionality of calixpyrrole hydrogen bond donors for selectivity is investigated. As demonstrated this hybrid receptor‐sensor shows a remarkable selectivity for orthophosphate even in the presence of other phosphates and anions found in cellular materials (Kassoc H2PO4−>H2P2O72−>AMP−≫ADP2− or ATP3− over halides, nitrate, or hydrogen sulfate; all Na+ salts in water) but also cellular polyphosphate or phospholipids. This selectivity is harnessed in a real‐time monitoring of cell lysis by lysozyme, which releases orthophosphate and other phosphates and anions from the cells. This sensitive (LOD 0.4 μM) fluorescence‐based microscale method compares favorably with the state‐of‐the‐art techniques but can easily be practiced in a high‐throughput screening (HTS) manner. The anion binding and selectivity in aqueous solutions were investigated by NMR and put in context with phosphate binding of the parent calix[4]pyrrole. The microscopic understanding of anion binding by the hybrid receptor was then obtained from a combination of density functional theory (DFT), classical molecular dynamics (MD) with explicit water solvation, and ab initio MD (AIMD) simulations. Correlating the NMR and fluorescence binding data with studies of solvation of the receptor, phosphate anion, and the resulting complex confirms the binding is largely driven by entropic component (TΔS) associated with receptor and anion desolvation. [ABSTRACT FROM AUTHOR]

Phosphate transporters in yeast cells are responsible for phosphorus homeostasis and are also indirectly involved in the regulation of various adaptive processes. One of these processes is the adaptation to ethanol consumption, which requires significant changes in phosphorus metabolism. We have demonstrated that knockout mutations in the genes PHO87, PHO89, PHO90, and PHO91, encoding phosphate transporters, impair the adaptation of Saccharomyces cerevisiae to ethanol consumption at an ethanol concentration of 4%. For these mutant strains, an extension of the lag phase and a decrease in the growth rate at the active stage were observed. Mutant cells differed from the parental strain in the content of inorganic polyphosphates, but not orthophosphate: they contained less long-chain polyphosphates when cultivated on ethanol, but not on glucose. When cultivated in a medium containing 4% ethanol, the strain with a knockout mutation in the PHO84 gene encoding the transporter of phosphate and divalent metals, as well as knockout strains for the PHM6 and PHM7 genes responsible for the polyphosphate overplus, did not show any growth differences compared to the parent strain in the medium with 4% ethanol. The possible role of phosphate transporters and inorganic polyphosphates in the adaptation of yeast to ethanol consumption is discussed. [ABSTRACT FROM AUTHOR]

The contact pathway of blood clotting has received intense interest in recent years as studies have linked it to thrombosis, inflammation, and innate immunity. Because the contact pathway plays little to no role in normal hemostasis, it has emerged as a potential target for safer thromboprotection, relative to currently approved antithrombotic drugs which all target the final common pathway of blood clotting. Research since the mid-2000s has identified polyphosphate, DNA, and RNA as important triggers of the contact pathway with roles in thrombosis, although these molecules also modulate blood clotting and inflammation via mechanisms other than the contact pathway of the clotting cascade. The most significant source of extracellular DNA in many disease settings is in the form of neutrophil extracellular traps (NETs), which have been shown to contribute to incidence and severity of thrombosis. This review summarizes known roles of extracellular polyphosphate and nucleic acids in thrombosis, with an emphasis on novel agents under current development that target the prothrombotic activities of polyphosphate and NETs. [ABSTRACT FROM AUTHOR]

Dissolved organic phosphorus (DOP) contains compounds with phosphoester, phosphoanhydride, and phosphorus–carbon bonds. While DOP holds significant nutritional value for marine microorganisms, the bioavailability of each bond-class to the widespread cyanobacterium Synechococcus remains largely unknown. This study evaluates bond-class specific DOP utilization by Synechococcus strains from open and coastal oceans. Both strains exhibited comparable growth rates when provided phosphate, a phosphoanhydride [3-polyphosphate and 45-polyphosphate], or a DOP compound with both phosphoanhydride and phosphoester bonds (adenosine 5′-triphosphate). Growth rates on phosphoesters [glucose-6-phosphate, adenosine 5′-monophosphate, bis(4-methylumbelliferyl) phosphate] were variable, and neither strain grew on selected phosphorus–carbon compounds. Both strains hydrolyzed 3-polyphosphate, then adenosine 5′-triphosphate, and lastly adenosine 5′-monophosphate, exhibiting preferential enzymatic hydrolysis of phosphoanhydride bonds. The strains' exoproteomes contained phosphorus hydrolases, which combined with enhanced cell-free hydrolysis of 3-polyphosphate and adenosine 5′-triphosphate under phosphate deficiency, suggests active mineralization of phosphoanhydride bonds by these exoproteins. Synechococcus alkaline phosphatases presented broad substrate specificities, including activity toward the phosphoanhydride 3-polyphosphate, with varying affinities between strains. Collectively, these findings underscore the potentially significant role of compounds with phosphoanhydride bonds in Synechococcus phosphorus nutrition and highlight varied growth and enzymatic responses to molecular diversity within DOP bond-classes, thereby expanding our understanding of microbially mediated DOP cycling in marine ecosystems. [ABSTRACT FROM AUTHOR]

β-Aspartyl compounds, such as β-aspartyl hydroxamate (serine racemase inhibitor), β-aspartyl- l -lysine (moisture retention), and β-aspartyl- l -tryptophan (immunomodulator) are physiologically active compounds. There is limited literature on the development of effective methods of production of β-aspartyl compounds. In this study, we describe the biochemical characterization of asparagine synthetase (AS) from Streptococcus thermophilus NBRC 13957 (StAS) and the enzymatic synthesis of β-aspartyl compounds using StAS. Recombinant StAS was expressed in Escherichia coli BL21(DE3) and it displayed activity towards hydroxylamine, methylamine, ethylamine, and ammonia, as acceptors of the β-aspartyl moiety. StAS exhibited higher activity toward hydroxylamine and ethylamine as acceptor substrates compared with the enzymes from Lactobacillus delbrueckii NBRC 13953, Lactobacillus reuteri NBRC 15892, and E. coli. The coupling of the synthesis of β-aspartyl compounds by StAS with an ATP-regeneration system using polyphosphate kinase from Deinococcus proteoliticus NBRC 101906 displayed an approximately 2.5-fold increase in the production of β-aspartylhydroxamate from 1.06 mM to 2.53 mM after a 76-h reaction. [ABSTRACT FROM AUTHOR]

Trypanosoma cruzi is the etiologic agent of Chagas disease, an infection that can lead to the development of cardiac fibrosis, which is characterized by the deposition of extracellular matrix (ECM) components in the interstitial region of the myocardium. The parasite itself can induce myofibroblast differentiation of cardiac fibroblast in vitro, leading to increased expression of ECM. Inorganic polyphosphate (polyP) is a linear polymer of orthophosphate that can also induce myofibroblast differentiation and deposition of ECM components and is highly abundant in T. cruzi. PolyP can modify proteins post-translationally by non-enzymatic polyphosphorylation of lysine residues of poly-acidic, serine-(S) and lysine (K)-rich (PASK) motifs. In this work, we used a bioinformatics screen and identified the presence of PASK domains in several surface proteins of T. cruzi. We also detected polyP in the external surface of its different life cycle stages and confirmed the stimulation of host cell fibrosis by trypomastigote infection. However, we were not able to detect significant secretion of the polymer or activation of transforming growth factor beta (TGF-β), an important factor for the generation of fibrosis by inorganic polyP- or trypomastigote-conditioned medium. [ABSTRACT FROM AUTHOR]

The Hofmeister series categorizes ions based on their effects on protein stability, yet the microscopic mechanism remains a mystery. In this series, NaCl is neutral, Na2SO4 and Na2HPO4 are kosmotropic, while GdmCl and NaSCN are chaotropic. This study employs CD and NMR to investigate the effects of NaCl, Na2SO4, and Na2HPO4 on the conformation, stability, binding, and backbone dynamics (ps-ns and µs-ms time scales) of the WW4 domain with a high stability and accessible side chains at concentrations ≤ 200 mM. The results indicated that none of the three salts altered the conformation of WW4 or showed significant binding to the four aliphatic hydrophobic side chains. NaCl had no effect on its thermal stability, while Na2SO4 and Na2HPO4 enhanced the stability by ~5 °C. Interestingly, NaCl only weakly interacted with the Arg27 amide proton, whereas Na2SO4 bound to Arg27 and Phe31 amide protons with Kd of 32.7 and 41.6 mM, respectively. Na2HPO4, however, bound in a non-saturable manner to Trp9, His24, and Asn36 amide protons. While the three salts had negligible effects on ps-ns backbone dynamics, NaCl and Na2SO4 displayed no effect while Na2HPO4 significantly increased the µs-ms backbone dynamics. These findings, combined with our recent results with GdmCl and NaSCN, suggest a microscopic mechanism for the Hofmeister series. Additionally, the data revealed a lack of simple correlation between thermodynamic stability and backbone dynamics, most likely due to enthalpy–entropy compensation. Our study rationalizes the selection of chloride and phosphate as the primary anions in extracellular and intracellular spaces, as well as polyphosphate as a primitive chaperone in certain single-cell organisms. [ABSTRACT FROM AUTHOR]

The systematic transfer of solvent‐free, additive flame retardant (FR) formulations from epoxy resins to glass fiber‐reinforced epoxy composites (GFRECs) through prepregs is difficult. Additionally, obtaining data on their post‐fire mechanics is often challenging. Utilizing melamine polyphosphate (MPP), ammonium polyphosphate (APP), and silane‐coated ammonium polyphosphate (SiAPP) FRs with low‐melting inorganic silicates (InSi) in an 8:2 proportion and 10% loading by weight in a diglycidyl ether of bisphenol A (DGEBA) resin, a systematic investigation of the processing properties, room‐temperature mechanics, and temperature‐based mechanics of the systems was performed. The resin was cured with a dicyandiamide hardener (DICY) and a urone accelerator. The results revealed no substantial impact of these FRs at the current loading on the resin's glass transition temperature or processability. However, the fire residues from cone calorimetry tests of the composites containing FRs were found to be only 15‐20% of the thickness of the resins, implying a suppression of intumescence upon transfer. At room temperature, the decrease in the flexural modulus for the composites containing FRs was negligible. Exposure of the composites in a furnace at 400°C as a preliminary study before ignition tests was shown to cause significant flexural moduli reductions after 2.5 min of exposure and complete delamination after 3 min making further testing unviable. This study emphasizes the need for future research on recovering modes of action upon transfer of FR formulations from resins to composites. Based on the challenges outlined in this investigation, sample adaptation methods for post‐fire analysis will be developed in a future study. Highlights: Processibility of resins for prepreg production unaffected by polyphosphate/inorganic silicate flame retardants (FRs).FR formulations had a negligible effect on the mechanics of the composites.15%–25% increase in the fracture toughness of the DGEBA‐based resin matrix with FRs.Suppression of intumescent behavior in the composites verified quantitatively.Significant reduction in flexural moduli of the composites post‐400°C exposure in a furnace. [ABSTRACT FROM AUTHOR]

Polyphosphates (Poly-P) are known to fulfil several important physiological functions. Many microorganisms can accumulate large amounts of Poly-P in their biomass. Regardless of these facts, systematic research on Poly-P in soil is missing, probably due to the absence of any method of direct Poly-P quantification. In this study, we attempted to unequivocally prove the presence of Poly-P in the biomass of soil microorganisms and quantify their extractability and contribution to microbial biomass phosphorus. To do so, we combined several approaches that can indicate Poly-P presence in soil microbial biomass indirectly, i.e. growth of soil inoculum on media without phosphorus, associated with measurement of changes in the microbial biomass stoichiometry, and the colour of the microbial suspension stained by the Neisser method. All soil microbial communities exhibited growth on media without phosphorus. As the growth on this media depleted Poly-P content, the biomass carbon to phosphorus and nitrogen to phosphorus ratio increased and the colour of the microbial suspension stained by the Neisser method changed predictively. The associated Poly-P addition experiment indicated that the recovery of added Poly-P from soil in form of soluble reactive phosphorus in sodium bicarbonate extract may reach up to 93% mainly due to abiotic depolymerization. Using a simple stoichiometric model applied to measured data, we calculated that the Poly-P content of microbial biomass in our soils may be up to 45 or 70% of total microbial biomass phosphorus depending on the assumptions applied regarding parameter values. We discuss the magnitude of error associated with the measurement of soil microbial phosphorus due to the high extractability of Poly-P. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an important and irreplaceable macronutrient. It is central to energy and information storage and exchange in living cells. P is an element with a "broken geochemical cycle" since it lacks abundant volatile compounds capable of closing the P cycle. P fertilizers are critical for global food security, but the reserves of minable P are scarce and non-evenly distributed between countries of the world. Accordingly, the risks of global crisis due to limited access to P reserves are expected to be graver than those entailed by competition for fossil hydrocarbons. Paradoxically, despite the scarcity and value of P reserves, its usage is extremely inefficient: the current waste rate reaches 80% giving rise to a plethora of unwanted consequences such as eutrophication leading to harmful algal blooms. Microalgal biotechnology is a promising solution to tackle this challenge. The proposed review briefly presents the relevant aspects of microalgal P metabolism such as cell P reserve composition and turnover, and the regulation of P uptake kinetics for maximization of P uptake efficiency with a focus on novel knowledge. The multifaceted role of polyPhosphates, the largest cell depot for P, is discussed with emphasis on the P toxicity mediated by short-chain polyPhosphates. Opportunities and hurdles of P bioremoval via P uptake from waste streams with microalgal cultures, either suspended or immobilized, are discussed. Possible avenues of P-rich microalgal biomass such as biofertilizer production or extraction of valuable polyPhosphates and other bioproducts are considered. The review concludes with a comprehensive assessment of the current potential of microalgal biotechnology for ensuring the sustainable usage of phosphorus. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the bleaching efficacy and effects on enamel properties of experimental gels with carbamide peroxide (CP; 10%) or hydrogen peroxide (HP; 6%) containing calcium polyphosphate sub-microparticles (CaPPs). Methods: A total of 216 bovine tooth specimens were divided for microhardness and color analyses (n = 108) and block randomized into nine groups (n = 12): (G1) commercial CP (Whiteness Perfect, FGM; Brazil); (G2) experimental CP; (G3) CP-0.5%CaPPs; (G4) CP-1.5%CaPPs; (G5) commercial HP (Potenza Bianco, PHS; Brazil); (G6) experimental HP; (G7) HP-0.5%CaPPs; (G8) HP-1.5%CaPPs; (G9) artificial saliva. The gels' pH values were determined with a bench pH meter. Color (ΔE, ΔE00, ΔWID) and microhardness variation were evaluated before and after the therapy. Part of the specimens used for microhardness was submitted to the scanning electron microscopy (SEM) (n = 3) and energy-dispersive X-ray spectroscopy EDX (n = 3) analyses. Statistical analyses were performed in the R statistical software (α = 0.05). Linear mixed models for repeated measures in time were used to analyze microhardness and L* values. Generalized linear models were used to analyze the a*, b*, ΔE, ΔE00, and ΔWID, considering a group effect. The EDX data were analyzed using a one-way ANOVA with Tukey's test. Results: The gels' pH remained over 6,0. All gels effectively bleached the specimens and did not differ significantly. When compared to the control group, the hardness was significantly lower in the G1, G2, G6, and G7 groups. The G3, G4, G5, and G8 groups did not differ significantly (p > 0.05). Conclusion: The incorporation of CaPPs in low-concentration whitening gels reduces its negative effects on microhardness without interfering with their bleaching efficacy. [ABSTRACT FROM AUTHOR]

This study aimed to assess the effects of fluoridated varnishes supplemented with micrometric or nanosized sodium trimetaphosphate (TMPmicro or TMPnano, respectively) against enamel softening in an early erosive model in vitro. Bovine enamel blocks (with mean surface hardness [SH] between 330.0 and 380.0 kgf/mm2) were selected and randomly assigned according to their SH (n = 8) into the following groups: Placebo (no fluoride/TMP; negative control), 5% NaF (positive control), 5% NaF + 5%TMPmicro, 5% NaF + 2.5%TMPnano and 5% NaF + 5%TMPnano. Blocks received a single application of the varnishes and were immersed in artificial saliva (6 h). Thereafter, the varnishes were removed and the blocks were subjected to four individual erosive challenges (1 min, citric acid, 0.75%, pH = 3.5, under agitation); SH was determined after each challenge. Data were subjected to ANOVA and Student–Newman–Keuls' test (p < 0.05). Overall, the highest %SH loss was observed for the Placebo, followed by 5% NaF, 5% NaF + 5% TMPmicro, and both varnishes containing TMPnano, without significant differences between 2.5% and 5% TMPnano. It was concluded that TMP enhanced the effects of a 5% NaF varnish against enamel softening in an early erosive model in vitro, with an additional benefit from the use of nanoparticles over microparticles. [ABSTRACT FROM AUTHOR]

This article discusses the importance of water pretreatment for businesses that rely on equipment such as steamers, hot water heaters, coffee makers, and ice machines. It explains that water hardness, caused by calcium and magnesium ions, can lead to scale formation and inefficient operation of equipment. The article introduces various anti-scale technologies, including ion-exchange resins and phosphate/polyphosphates, as well as a new media blend that has shown promising results in controlling scale buildup and corrosion. The document includes a test conducted in Henderson, NV, comparing different anti-scale media, with Media 3 performing the best. Overall, the study emphasizes the significance of addressing scale issues in water treatment to prevent equipment problems. [Extracted from the article]

Background: The innate immunity acts during the early phases of infection and its failure in response to a multilayer network of co-infections is cause of immune system dysregulation. Epidemiological SARS-CoV-2 infections data, show that Influenza Virus (FLU-A-B-C) and Respiratory Syncytial Virus (RSV) are co-habiting those respiratory traits. These viruses, especially in children (mostly affected by 'multi-system inflammatory syndrome in children' [MIS-C] and the winter pandemic FLU), in the aged population, and in 'fragile' patients are causing alteration in immune response. Then, bacterial and fungal pathogens are also co-habiting the upper respiratory traits (e.g., Staphylococcus aureus and Candida albicans), thus contributing to morbidity in those COVID-19 affected patients. Methods: Liquid chromatography coupled with high-resolution mass spectrometry using the quadrupole orbital ion trap analyser (i.e., UHPLC-Q-Orbitrap HRMS) was adopted to measure the polyphenols content of a new nutraceutical formula (Solution-3). Viral infections with SARS-CoV-2 (EG.5), FLU-A and RSV-A viruses (as performed in BLS3 authorised laboratory) and real time RT-PCR (qPCR) assay were used to test the antiviral action of the nutraceutical formula. Dilution susceptibility tests have been used to estimate the minimum inhibitory and bactericidal concentration (MIC and MBC, respectively) of Solution-3 on a variety of microorganisms belonging to Gram positive/ negative bacteria and fungi. Transcriptomic data analyses and functional genomics (i.e., RNAseq and data mining), coupled to qPCR and ELISA assays have been used to investigate the mechanisms of action of the nutraceutical formula on those processes involved in innate immune response. Results: Here, we have tested the combination of natural products containing higher amounts of polyphenols (i.e., propolis, Verbascum thapsus L., and Thymus vulgaris L.), together with the inorganic long chain polyphosphates 'polyPs' with antiviral, antibacterial, and antifungal behaviours, against SARS-CoV-2, FLU-A, RSV-A, Gram positive/ negative bacteria and fungi (i.e., Candida albicans). These components synergistically exert an immunomodulatory action by enhancing those processes involved in innate immune response (e.g., cytokines: IFNγ, TNFα, IL-10, IL-6/12; chemokines: CXCL1; antimicrobial peptides: HBD-2, LL-37; complement system: C3). Conclusion: The prophylactic antimicrobial success of this nutraceutical formula against SARS-CoV-2, FLU-A and RSV-A viruses, together with the common bacteria and fungi co-infections as present in human oral cavity, is expected to be valuable. [ABSTRACT FROM AUTHOR]

Inositol hexaphosphate (InsP6) is the major storage form of phosphorus in seeds. Reducing seed InsP6 content is a breeding objective in agriculture, as InsP6 negatively impacts animal nutrition and the environment. Nevertheless, how InsP6 accumulation is regulated remains largely unknown. Here, we identify a clade of receptor-like cytoplasmic kinases (RLCKs), named Inositol Polyphosphate-related Cytoplasmic Kinases 1-6 (IPCK1-IPCK6), deeply involved in InsP6 accumulation. The InsP6 concentration is dramatically reduced in seeds of ipck quadruple (T-4m/C-4m) and quintuple (C-5m) mutants, accompanied with the obviously increase of phosphate (Pi) concentration. The plasma membrane-localized IPCKs recruit IPK1 involved in InsP6 synthesis, and facilitate its binding and activity via phosphorylation of GRF 14-3-3 proteins. IPCKs also recruit IPK2s and PI-PLCs required for InsP4/InsP5 and InsP3 biosynthesis respectively, to form a potential IPCK-GRF-PLC-IPK2-IPK1 complex. Our findings therefore uncover a regulatory mechanism of InsP6 accumulation governed by IPCKs, shedding light on the mechanisms of InsP biosynthesis in eukaryotes. Inositol hexaphosphates (InsP6) are ubiquitous in eukaryotes and regulates a plethora of cellular functions. Here the authors identify a set of receptor-like cytoplasmic kinases that work in concert with 14-3-3- proteins to regulate InsP6 synthesis and accumulation and Pi homeostasis in Arabidopsis. [ABSTRACT FROM AUTHOR]

In this study, fly ash (FA) which mainly consists of SiO2, Al2O3, Fe2O3, MgO, and CaO, was used as a synergistic additive (1–5 wt %) to improve the effectiveness of an intumescent flame retardant (IFR) system (25 wt %) in high density polyethylene (HDPE). IFR system composed of ammonium polyphosphate and pentaerythritol (3/1 ratio), and different amounts of FA were incorporated homogeneously into HDPE. Thermogravimetric analyses and thermal conductivity measurements were performed to determine the thermal properties. Meanwhile, limiting oxygen index, UL 94 vertical burning, and cone calorimetry tests were performed to investigate the fire resistance. Furthermore, the effects of IFR/FA additions on the mechanical properties were determined. The experimental results showed that IFR and IFR/FA additions resulted in early degradation with lower rates, and the residual mass values increased due to the char layers and the FA content. Also, IFR addition increased the thermal conductivity coefficient from 0.451 W/mK to 0.462 W/mK and IFR/FA additions further increased the coefficient up to 0.506 W/mK. Although the sample included only 25 wt % IFR could meet the requirements of UL 94 V-2 with a LOI value of 25.0%, 2, 3 and 4 wt % FA additions satisfied the criteria of UL 94 V-0 with a LOI value of 26.6%. In addition, the cone calorimeter results revealed that the peak heat release rates and total heat released values decreased with IFR (25 wt %) and FA (2, 3, and 4 wt %) additions. Furthermore, CO, CO2, and soot emissions of the composites significantly reduced with respect to HDPE. The NO increased with IFR additions due to the nitrogen content of APP. 25% IFR addition caused decreases in the tensile strength, tensile modulus, and Izod impact strength. However, FA additions slightly enhanced the mechanical properties of HDPE/IFR composite. [ABSTRACT FROM AUTHOR]

The essence of drug delivery is to use an appropriate carrier that delivers the active substance to the appropriate pathogenic site at a specific time. This study aims to develop a novel drug carrier characterized by the controlled and targeted release of risedronate (RSD). The search for new routes to deliver RSD is important because oral delivery has many disadvantages. The carrier proposed in this work is composed of gelatin, polyphosphates, and zinc. The zinc contained in the carrier is responsible for coordinating the drug. The resulting material releases RSD in a controlled manner. The rate of delivery of the substance to the body depends on the pH of the environment. This study investigated the delivery of RSD in a neutral environment, where the process exhibited a prolonged and consistent release rate. This process has also been studied in an acidic environment, which accelerates the release of the drug. Mixed-environment studies were also conducted. Initially, the drug was released in a neutral environment, and then the conditions rapidly changed to acidic. In this case, the carrier demonstrated high stability and controlled release, adapting the rate of drug release to the prevailing environmental conditions. The presented results indicate the great potential of the new gelatin-based carrier in the delivery of risedronate. [ABSTRACT FROM AUTHOR]

This research aims to track the chemical composition and fine structure of tribofilm, primarily considering sulfur- and phosphorus-related compounds in response to different applied loads and temperatures on the boundary lubrication regime, where the commercially formulated engine oil was adopted as lubricant. The results clearly reveal the formation of iron polyphosphate-rich tribofilm preferentially on the moving cast-iron surfaces, with increasing amount of FeS2/FeS2xOx species along with heavier load and higher temperature. Nevertheless, FeS2/FeS2xOx species gradually decrease rather than as the intermediate layer or increasingly concentrate on the substrate surface, which is greatly different from the previously reported tribofilm primarily consisting of zinc/iron polyphosphate and sulfide mixtures. More detailed information regarding how sulfur- and phosphorus-related species distribute spatially across the whole tribofilm thickness was given by ToF-SIMS technique. [ABSTRACT FROM AUTHOR]

Regulatory cystathionine β-synthase (CBS) domains are widespread in proteins; however, difficulty in structure determination prevents a comprehensive understanding of the underlying regulation mechanism. Tetrameric microbial inorganic pyrophosphatase containing such domains (CBS-PPase) is allosterically inhibited by AMP and ADP and activated by ATP and cell alarmones diadenosine polyphosphates. Each CBS-PPase subunit contains a pair of CBS domains but binds cooperatively to only one molecule of the mono-adenosine derivatives. We used site-directed mutagenesis of Desulfitobacterium hafniense CBS-PPase to identify the key elements determining the direction of the effect (activation or inhibition) and the "half-of-the-sites" ligand binding stoichiometry. Seven amino acid residues were selected in the CBS1 domain, based on the available X-ray structure of the regulatory domains, and substituted by alanine and other residues. The interaction of 11 CBS-PPase variants with the regulating ligands was characterized by activity measurements and isothermal titration calorimetry. Lys100 replacement reversed the effect of ADP from inhibition to activation, whereas Lys95 and Gly118 replacements made ADP an activator at low concentrations but an inhibitor at high concentrations. Replacement of these residues for alanine increased the stoichiometry of mono-adenosine phosphate binding by twofold. These findings identified several key protein residues and suggested a "two non-interacting pairs of interacting regulatory sites" concept in CBS-PPase regulation. [ABSTRACT FROM AUTHOR]

In recent years, research has focused heavily on the investigation of functionalized ammonium polyphosphate (APP) flame retardants to improve the fire safety of epoxy resins (EP). The reason for this is the dual nature of APP’s performance in fire protection of EP. This article provides a comprehensive overview of the advances in the use of functionalized APP flame retardants to improve the fire resistance of EP materials. It then presents the improvement of the modification of the functionalized APP flame retardants in terms of the hydrophobicity, compatibility and catalytic ability of the flame retardants, as well as the effects on the fire resistance, heat resistance, smoke reduction and mechanical properties of the EP composites. After the summary and comparison of the relevant studies, it is clear that the functionalized APP flame retardants can effectively improve the fire safety of EP composites and offset the adverse effects of APP in EP flame retardant applications. In addition, APP flame retardants can obtain various excellent functions through the use of materials with different properties, and the interaction between APP and materials can also lead to more efficient fire protection. However, the current problem is to find ways to streamline the process and minimise the costs associated with functionalized APP flame retardants, as well as to use them effectively in industrial production. We hope that this review can provide valuable hints and insights for the practical application of functionalized APP in EP and perspectives for future research. [ABSTRACT FROM AUTHOR]

Phosphates and polyphosphates play ubiquitous roles in biology as integral structural components of cell membranes and bone, or as vehicles of energy storage via adenosine triphosphate and phosphocreatine. The solution phase space of phosphate species appears more complex than previously known. We present nuclear magnetic resonance (NMR) and cryogenic transmission electron microscopy (cryo-TEM) experiments that suggest phosphate species including orthophosphates, pyrophosphates, and adenosine phosphates associate into dynamic assemblies in dilute solutions that are spectroscopically "dark." Cryo-TEM provides visual evidence of the formation of spherical assemblies tens of nanometers in size, while NMR indicates that a majority population of phosphates remain as unassociated ions in exchange with spectroscopically invisible assemblies. The formation of these assemblies is reversibly and entropically driven by the partial dehydration of phosphate groups, as verified by diffusion-ordered spectroscopy (DOSY), indicating a thermodynamic state of assembly held together by multivalent interactions between the phosphates. Molecular dynamics simulations further corroborate that orthophosphates readily cluster in aqueous solutions. This study presents the surprising discovery that phosphate-containing molecules, ubiquitously present in the biological milieu, can readily form dynamic assemblies under a wide range of commonly used solution conditions, highlighting a hitherto unreported property of phosphate's native state in biological solutions.

Introduction: Nitrososphaeria, formerly known as Thaumarchaeota, constitute a diverse and widespread group of ammonia-oxidizing archaea (AOA) inhabiting ubiquitously in marine and terrestrial environments, playing a pivotal role in global nitrogen cycling. Despite their importance in Earth's ecosystems, the cellular organization of AOA remains largely unexplored, leading to a significant unanswered question of how the machinery of these organisms underpins metabolic functions. Methods: In this study, we combined spherical-chromatic-aberration-corrected cryo-electron tomography (cryo-ET), scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDS) to unveil the cellular organization and elemental composition of Nitrosopumilus maritimus SCM1, a representative member of marine Nitrososphaeria. Results and Discussion: Our tomograms show the native ultrastructural morphology of SCM1 and one to several dense storage granules in the cytoplasm. STEM-EDS analysis identifies two types of storage granules: one type is possibly composed of polyphosphate and the other polyhydroxyalkanoate. With precise measurements using cryo-ET, we observed low quantity and density of ribosomes in SCM1 cells, which are in alignment with the documented slow growth of AOA in laboratory cultures. Collectively, these findings provide visual evidence supporting the resilience of AOA in the vast oligotrophic marine environment. [ABSTRACT FROM AUTHOR]

Remove and recovery of phosphorus from wastewater is expected to be a promising strategy to solve the shortage of phosphorus resources and control the water environment pollution. In this study, induced crystallization coupled biological phosphorus removal (IC-BPR) process was established to achieve simultaneous removal and recovery of phosphorus in wastewater. The effects of side stream ratio (SSR) on the removal and recovery efficiency of phosphorus and the microbial community structure were explored. The results indicated that the SSR of 40% was optimal to phosphorus removal and recovery in the IC-BPR. The total phosphorus removal efficiency was 94.23% under the SSR of 40%, of which the phosphorus removal efficiency by IC accounted for 74.87%. And the total phosphorus recovery efficiency was 67.29%. The particle size and crystal structure analysis of the crystallized products indicated that the increase of SSR was conductive to heterogeneous crystallization. Furthermore, typical polyphosphate accumulation organisms (PAOs), including Rhodocyclaceae, Acinetobacter, and Dechloromonasin, were enriched under the side stream ratio of 40%. And functional genes related to amino acid transport and metabolism, energy production and conversion were activated. The above results indicated that the IC could significantly enhance the removal and recovery of phosphorus under a suitable SSR condition. It will provide important reference for wastewater treatment coupled phosphorus resource recovery technology. [ABSTRACT FROM AUTHOR]

Uncontrolled bleeding has long been a major challenge for the health care system. Bleeding, whether caused by trauma, genetic disease, surgery, or medications, can cause life-threatening damage or even death. Inorganic haemostatic materials, while effective in haemostasis, tend to be less biocompatible. In recent years, inorganic composite haemostatic materials have received widespread attention for their ability to rapidly stop bleeding and for their low biotoxicity. This review focuses on the haemostatic mechanisms of silicate minerals (zeolite, montmorillonite, and bioglass), silica (mesoporous silica and diatomaceous silica), polyphosphates, inorganic carbon materials (graphene and carbon nanotubes), metal-containing materials (metal–organic frameworks) and related composite haemostatic materials. In this review, not only the preparation of various inorganic composite haemostatic materials but also their haemostatic mechanisms and haemostatic effects are described in detail. At the end of the review, we summarize the advantages and disadvantages of inorganic composite haemostatic materials and introduce their challenges and prospects. [ABSTRACT FROM AUTHOR]

The linear polymer polyphosphate (poly-P) is present across all three domains of life and serves diverse physiological functions. The enzyme polyphosphate kinase (Ppk) is responsible for poly-P synthesis, whereas poly-P degradation is carried out by the enzyme exopolyphosphatase (Ppx). In many Lactobacillaceae, the Ppk-encoding gene (ppk) is found clustered together with two genes encoding putative exopolyphosphatases (ppx1 and ppx2) each having different domain compositions, with the gene order ppx1-ppk-ppx2. However, the specific function of these ppx genes remains unexplored. An in-frame deletion of ppx1 in Lacticaseibacillus paracasei BL23 resulted in bacteria unable to accumulate poly-P, whereas the disruption of ppx2 did not affect poly-P synthesis. The expression of ppk was not altered in the Δppx1 strain, and poly-P synthesis in this strain was only restored by expressing ppx1 in trans. Moreover, no poly-P synthesis was observed when ppk was expressed from a plasmid in the Δppx1 strain. Purified Ppx2 exhibited in vitro exopolyphosphatase activity, whereas no in vitro enzymatic activity could be demonstrated for Ppx1. This observation corresponds with the absence in Ppx1 of conserved motifs essential for catalysis found in characterized exopolyphosphatases. Furthermore, assays with purified Ppk and Ppx1 evidenced that Ppx1 enhanced Ppk activity. These results demonstrate that Ppx1 is essential for poly-P synthesis in Lc. paracasei and have unveiled, for the first time, an unexpected role of Ppx1 exopolyphosphatase in poly-P synthesis. [ABSTRACT FROM AUTHOR]

Protein–protein and protein–mineral interactions can result in defects, such as sedimentation and age gelation, during the storage of high-protein beverages. It is well known that age gelation can be delayed by adding cyclic polyphosphates such as sodium hexametaphosphate (SHMP). This study aims to assess the influence of different phosphate chain lengths of SHMP on the physicochemical properties of high-protein dispersions. The effect of adding different SHMP concentrations at 0%, 0.15%, and 0.25% (w/w) before and after heating of 6%, 8%, and 10% (w/w) milk protein concentrate dispersions was studied. The phosphate chain lengths of SHMPs used in this study were 16.47, 13.31, and 9.88, and they were classified as long-, medium-, and short-chain SHMPs, respectively. Apparent viscosity, particle size, heat coagulation time (HCT), color, and turbidity were evaluated. It was observed that the addition of SHMP (0.15% and 0.25%) increased the apparent viscosity of MPC dispersions. However, the chain length and the concentration of the added SHMP had no significant (p > 0.05) effect on the apparent viscosity after heating the dispersions. The HCT of a dispersion containing 6%, 8%, and 10% protein with no SHMP added was 15.28, 15.61, and 11.35 min, respectively. The addition of SHMP at both levels (0.15% and 0.25%) significantly increased the HCT. Protein dispersions (6%, 8%, and 10%) containing 0.25% short-chain SHMP had the highest HCT at 19.29, 19.61, and 16.09 min, respectively. Therefore, the chain length and concentration of added SHMP significantly affected the HCT of unheated protein dispersion (p < 0.05). [ABSTRACT FROM AUTHOR]

Dinucleoside 5',5'‐polyphosphates (NpnNs) play essential roles in various biological processes. Access to these high value‐added compounds, while avoiding the many drawbacks of solution phase synthesis, is a challenge that has been overcome thanks to mechanochemistry. A straightforward solid‐state synthesis based on activation of phosphate or pyrophosphate sodium salts to their diimidazolides, followed by coupling with commercially available nucleotides, under air conditions, gave symmetrical NpnNs. The scope ranged from Np3Ns to highly challenging Np6Ns. The methodology has also been implemented using medronic acid and imidodiphosphate to obtain NpnNs analogues, some of which are unprecedented. [ABSTRACT FROM AUTHOR]

Medium-sized 5- and 6-membered ring lactams are molecules with remarkable stability, in contrast to smaller β-lactams. As monomers, they grant access to nylon-4 and nylon-5, which are alternative polyamides to widespread caprolactam-based nylon-6. Chemical hydrolysis of monocyclic γ- and δ-lactams to the corresponding amino acids requires harsh reaction conditions and up to now, no mild (enzymatic) protocol has been reported. Herein, the biocatalytic potential of a pair of heterologously expressed bacterial ATP-dependent oxoprolinases – OplA and OplB – was exploited. Strong activity in the presence of excess of ATP was monitored on δ-valerolactam and derivatives thereof, while trace activity was detected on γ-butyrolactam. An ATP recycling system based on cheap Graham's salt (sodium metaphosphate) and a polyphosphate kinase allowed the use of catalytic amounts of ATP, leading to up to full conversion of 10 mM δ-valerolactam at 30 °C in aqueous medium. Further improvements were obtained by co-expressing OplA and OplB using the pETDuet1 vector, a strategy which enhanced the soluble expression yield and the protein stability. Finally, a range of phosphodonors was investigated in place of ATP. With acetyl phosphate and carbamoyl phosphate, turnover numbers up to 176 were reached, providing hints on a possible mechanism, which was studied by 31P-NMR. [ABSTRACT FROM AUTHOR]

The maintenance of phosphate homeostasis serves as a foundation for energy metabolism and signal transduction processes in all living organisms. Inositol pyrophosphates (PP-InsPs), composed of an inositol ring decorated with monophosphate and diphosphate moieties, and inorganic polyphosphate (polyP), chains of orthophosphate residues linked by phosphoanhydride bonds, are energy-rich biomolecules that play critical roles in phosphate homeostasis. There is a complex interplay between these two phosphaterich molecules, and they share an interdependent relationship with cellular adenosine triphosphate (ATP) and inorganic phosphate (Pi). In eukaryotes, the enzymes involved in PP-InsP synthesis show some degree of conservation across species, whereas distinct enzymology exists for polyP synthesis among different organisms. In fact, the mechanism of polyP synthesis in metazoans, including mammals, is still unclear. Early studies on PPInsP and polyP synthesis were conducted in the slime mould Dictyostelium discoideum, but it is in the budding yeast Saccharomyces cerevisiae that a clear understanding of the interplay between polyP, PP-InsPs, and Pi homeostasis has now been established. Recent research has shed more light on the influence of PP-InsPs on polyP in mammals, and the regulation of both these molecules by cellular ATP and Pi levels. In this review we will discuss the cross-talk between PP-InsPs, polyP, ATP, and Pi in the context of budding yeast, slime mould, and mammals. We will also highlight the similarities and differences in the relationship between these phosphate-rich biomolecules among this group of organisms. [ABSTRACT FROM AUTHOR]

Lyocell fiber, hailed as the "verdant filament of the 21st century," boasts elevated tensile strength, environmentally conscientious production practices, and innate biodegradability. Nonetheless, its intrinsic combustibility constitutes a noteworthy impediment to its pervasive utilization across textile and industrial domains. In a concerted effort to surmount this challenge, ammonium polyphosphate (APP) underwent modification through the infusion of N‐methylmorpholine‐N‐oxide (NMMO) molecules, amplifying its dispersibility within lyocell solutions. The resultant NMMO‐coated ammonium polyphosphate (NAPP) underwent meticulous characterization of both its structure and properties. Remarkably, lyocell fiber impregnated with 30% NAPP exhibited exemplary flame retardancy, enduring through 30 laundering cycles. Notably, its tensile strength remained notably robust at 139 MPa, demonstrating a mere 6.1% reduction in comparison to its pristine lyocell counterpart. This study delineates a promising trajectory for the fabrication of mechanically resilient lyocell fibers endowed with commendable flame‐retardant attributes. Highlights: The raw material is waste cotton textiles, prepared on a green basis.The use of ultrasonic mixing and low‐speed stirring defoaming method and the use of room temperature spinning advantage of the production of flame retardant lyocell fiber.The amount of flame retardant is small, and the mechanical strength is reduced to a lesser extent.Good flame‐retardant effect and excellent water washing resistance. [ABSTRACT FROM AUTHOR]

Inorganic phosphate (Pi) concentration modulates polyphosphate (polyP) levels in diverse bacteria, affecting their physiology and survival. Lactiplantibacillus paraplantarum CRL 1905 is a lactic acid bacterium isolated from quinoa sourdough with biotechnological potential as starter, for initiating fermentation processes in food, and as antimicrobial-producing organism. The aim of this work was to evaluate the influence of the environmental Pi concentration on different physiological and molecular aspects of the CRL 1905 strain. Cells grown in a chemically defined medium containing high Pi (CDM + P) maintained elevated polyP levels up to late stationary phase and showed an enhanced bacterial survival and tolerance to oxidative stress. In Pi sufficiency condition (CDM-P), cells were ~ 25% longer than those grown in CDM + P, presented membrane vesicles and a ~ 3-fold higher capacity to form biofilm. Proteomic analysis indicated that proteins involved in the “carbohydrate transport and metabolism” and “energy production and conversion” categories were up-regulated in high Pi stationary phase cells, implying an active metabolism in this condition. On the other hand, stress-related chaperones and enzymes involved in cell surface modification were up-regulated in the CDM-P medium. Our results provide new insights to understand the CRL 1905 adaptations in response to differential Pi conditions. The adjustment of environmental Pi concentration constitutes a simple strategy to improve the cellular fitness of L. paraplantarum CRL 1905, which would benefit its potential as a microbial cell factory. [ABSTRACT FROM AUTHOR]

This review covers a group of non-covalently associated molecules, particularly proteins (NCAp), incorporated in the yeast cell wall (CW) with neither disulfide bridges with proteins covalently attached to polysaccharides nor other covalent bonds. Most NCAp, particularly Bgl2, are polysaccharide-remodeling enzymes. Either directly contacting their substrate or appearing as CW lipid-associated molecules, such as in vesicles, they represent the most movable enzymes and may play a central role in CW biogenesis. The absence of the covalent anchoring of NCAp allows them to be there where and when it is necessary. Another group of non-covalently attached to CW molecules are polyphosphates (polyP), the universal regulators of the activity of many enzymes. These anionic polymers are able to form complexes with metal ions and increase the diversity of non-covalent interactions through charged functional groups with both proteins and polysaccharides. The mechanism of regulation of polysaccharide-remodeling enzyme activity in the CW is unknown. We hypothesize that polyP content in the CW is regulated by another NCAp of the CW—acid phosphatase—which, along with post-translational modifications, may thus affect the activity, conformation and compartmentalization of Bgl2 and, possibly, some other polysaccharide-remodeling enzymes. [ABSTRACT FROM AUTHOR]

Immobilisation plays an important role in the industrial application of enzymes. The stabilisation and reusability of immobilised enzymes reduce the cost of the catalyst and facilitate their use in continuously operated reactors. For this purpose, an applicable type of immobilisation needs to be identified. In this study, we investigate the conversion of CDP and PolyP to CTP by NDP polyphosphate phosphotransferase 3 from Ruegeria pomeroyi (RpPPK2-3) and describe the covalent immobilisation of RpPPK2-3. In order to select a suitable carrier for the immobilisation of RpPPK2-3, a screening with different amino methacrylate (glutaraldehyde-pre-activated) and epoxy methacrylate carriers was carried out. The epoxy methacrylate carrier ECR8209M (Purolite®) was found to be the most suitable. With a half-life of 462 d when stored at 6 °C and a 50-fold reusability with a 93% residual activity, the immobilised enzyme showed a higher stability compared to the soluble enzyme with a half-life of 0.04 d. Although the half-life of the soluble enzyme could be increased to 32 d by adding PPi, it could not reach the stability of the immobilisate. Due to the resilience of the immobilisate, it is suitable for application in continuous reactor set-ups, e.g., packed-bed reactors. [ABSTRACT FROM AUTHOR]

To ensure fire safety, polymers are filled with flame retardants and smoke suppressants. To meet the highest requirements, it is essential to understand the decomposition of those polymeric materials. This study reveals interactions between polymer, smoke suppressants, and flame retardants, and discusses their impact on the materials' flame retardancy, smoke emission, smoke toxicity, and particle emission in conventional loadings to provide deeper general understanding. Low melting oxide glass, melem, spherical silica, sepiolite, melamine polyphosphate, and boehmite in an aluminum diethylphosphinate flame-retarded polyamide 6.6 were investigated. All smoke suppressants improve the protective layer and act as an adjuvant. Silica and melem performed best under forced flaming conditions. Spherical silica reduces the peak of heat release rate by 39% and the total heat evolved by 14%, whereas 10 wt% melem lowers the total smoke production by 41%. Melem alters the mode of action of aluminum diethylphosphinate from gas to more condensed phase activity. This change reduces flame inhibition and hence smoke toxicity, but further improves the protective layer due to charring reactions in the decomposition mechanism. In addition, the sizes of the smoke particles decrease because of the prolonged time in the pyrolytic zone. This study highlights that interactions between polymer, flame retardants, and smoke suppressants can significantly determine the smoking and burning behavior. [ABSTRACT FROM AUTHOR]

Photogeneration of hydrogen in microalgae is thought to be among the mechanisms increasing their resilience to stresses including those caused by nutrient deprivation by re-routing the flow of electrons and reducing power in the cell. Metabolism of phosphorus (P), an essential nutrient, and its reserve forms such as polyphosphate (PolyP), is affected by and plays a role in the responses to diverse stresses, too. However, the potential interplay of the capability of photogeneration of hydrogen and turnover of phosphorus-rich inclusions in stressed microalgae cells so far escaped the attention of researchers. Here, we present a quantitative ultrastructural view of the turnover of P-rich inclusions in the model microalga Chlamydomonas reinhardtii strains, the parent strain CC-425 and its hydEF-1 mutant lacking hydrogenase activity as a function of sulfur and oxygen availability in the medium. In addition to the electron microscopy cell image analysis of the studied strains, we followed the elemental composition of the inclusions in different (sub) compartments of the cells obtained with energy dispersive X-ray spectroscopy. The stress caused by sulfur deprivation and subsequent transition of the microalgae culture to anaerobic conditions declined the size of phosphorus-containing inclusions but increased their number in the parent strain. Overall, the accumulation of the phosphorus-rich inclusions in hydEF-1 mutant was much lower than in the fully functional parent strain regardless of the cultivation conditions. We believe that impaired hydrogenase activity and correspondingly reduced sink of electrons and reducing power in the mutant strain indirectly affects the turnover of P and its reserves in the cell. These effects were manifested by the changes in the abundance, morphology, and elemental composition of the P-containing inclusions. We hypothesized that the sulfur-deprivation stress increased the initiation of the biosynthesis of PolyP chains, but their elongation and hence the formation of large PolyP-containing inclusions was hindered by anaerobiosis. [ABSTRACT FROM AUTHOR]

One of the functions of inorganic polyphosphates (polyP) as compounds with phosphoester bonds is participation in energy metabolism. While yeast mitochondria contain their own pool of polyphosphates, the ways in which these polymers are involved in the functioning of mitochondria in these microorganisms are not well understood. The goal of the present work was to identify the effect of knockout mutations of the VTC4 gene of polyphosphate synthetase and the PPN1 gene of one of the polyphosphatases on the content of polyphosphates and polyphosphatase activity in mitochondria of S. cerevisiae and on the growth characteristics of the mutant strains on ethanol. Knockout of the VTC4 gene was shown to result in a significant decrease in the polyP content in the mitochondria. Knockout of the PPN1 gene led to the disappearance of polyphosphatase activity, but only to a slight increase in the content of mitochondrial polyphosphates during growth on glucose. When grown on ethanol, the polyP content in the mitochondria of this strain was similar to that of the parental strain, and in both strains it was approximately two times less than when grown on glucose. Both mutants were able to grow with ethanol as the carbon source; however, they exhibited a longer lag phase upon transition from glucose consumption to ethanol consumption. It was suggested that mitochondrial polyphosphates may represent the energy reserve of these organelles, which is necessary for the formation of full-fledged mitochondria during transition from glycolysis to oxidative phosphorylation. [ABSTRACT FROM AUTHOR]

When low molecular weight ammonium polyphosphate interacts with polyethylene polyamine, thermoplastic polymers containing fractions with glass transition temperatures Tglass ≥ –95°C are obtained. Their thermal and heat resistance, as well as moisture resistance, is measured at a humidity of 40–50%. The structure and chemical scheme for the formation of interaction products are proposed. [ABSTRACT FROM AUTHOR]

Inorganic polyphosphate (polyP) plays a vital role in cellular energy metabolism and signaling, owing to its structure and high‐energy phosphate bonds. Intracellular ATP functions both as a cellular energy source and a key factor in cell death, and ATP dynamics in tumor cells are crucial for advancing cancer therapy. In this study, we explored the interplay between polyP and ATP in cellular energy metabolism. Treatment with polyP did not affect cell proliferation of human non‐small cell lung cancer H1299 and human glioblastoma T98G cell lines as compared to their respective control cells until 72 h post‐treatment. The mitochondrial membrane potential (MMP) in polyP‐treated cells was low, contrasting with the time‐dependent increase observed in control cells. While the ATP content increased over time in untreated and Na‐phosphate‐treated control cells, it remained unchanged in polyP‐treated cells. Furthermore, the addition of cyclosporine A, a mitochondrial permeability transition pore (mPTP) inhibitor, failed to restore ATP levels in polyP‐treated cells. We performed lactate assays and western blot analysis to evaluate the effect of polyP on glucose metabolism and found no significant differences in lactate secretion or glucose‐6‐phosphate dehydrogenase (G6PD) activity between polyP‐treated and control cells. Additional pyruvate restored MMP but had no effect on the cellular ATP content in polyP‐treated cells. We observed no correlation between the Warburg effect and glucose metabolism during ATP depletion in polyP‐treated cells. Further investigation is warranted to explore the roles of polyP and ATP in cancer cell energy metabolism, which might offer potential avenues for therapeutic interventions. [ABSTRACT FROM AUTHOR]

Conserved Histidine Alpha-helical Domain (CHAD) proteins attached to the surface of polyphosphate (PolyP) have been studied in some bacteria and one archaeon. However, the activity of CHAD proteins is unknown beyond their interaction with PolyP granules. By using bioinformatic analysis, we report that several species of the biomining acidophilic bacteria contain orthologs of CHAD proteins with high sequence identity. Furthermore, the gene coding for the CHAD protein is in the same genetic context of the enzyme polyphosphate kinase (PPK), which is in charge of PolyP synthesis. Particularly, the group of ppk and CHAD genes is highly conserved. Metallosphaera sedula and other acidophilic archaea used in biomining also contain CHAD proteins. These archaea show high levels of identity in genes coding for a cluster having the same organization. Amongst these genes are chad and ppx. In general, both biomining bacteria and archaea contain high PolyP levels and are highly resistant to heavy metals. Therefore, the presence of this conserved genetic organization suggests a high relevance for their metabolism. It has been formerly reported that a crystallized CHAD protein contains a copper-binding site. Based on this previous knowledge, in the present report, it was determined that all analyzed CHAD proteins are very conserved at their structural level. In addition, it was found that the lack of YgiF, an Escherichia coli CHAD-containing protein, decreases copper resistance in this bacterium. This phenotype was not only complemented by transforming E. coli with YgiF but also by expressing CHAD from Acidithiobacillus ferrooxidans in it. Interestingly, the strains in which the possible copper-binding sites were mutated were also more metal sensitive. Based on these results, we propose that CHAD proteins are involved in copper resistance in microorganisms. These findings are very interesting and may eventually improve biomining operations in the future. [ABSTRACT FROM AUTHOR]

To examined alkaline phosphatase enzyme (ALP) activity and the effects of incorporating it in the thickener solution of a hydrogen-peroxide-based bleaching gel containing calcium-polyphosphate (CaPP) on the orthophosphate (PO43−) levels, bleaching effectiveness, and enamel microhardness. ALP activity was assessed at different pH levels and H2O2 concentrations, and in H2O- and Tris-based thickeners. Circular dichroism (CD) was used to examine the ALP secondary structure in water-, Tris-, or H2O2-based mediums. The PO43− levels were evaluated in thickeners with and without ALP. Enamel/dentin specimens were allocated into the following groups: control (without bleaching); commercial (Whiteness-HP-Maxx); Exp-H (H2O-based); CaPP-H; ALP-H (CaPP+ALP); Exp-T (Tris-based); CaPP-T; and ALP-T (CaPP+ALP). Color changes (ΔE/ΔE00) and the bleaching index (ΔWID) were calculated, and surface (SMH) and cross-sectional microhardness (CSMH) were assessed. The two-way ANOVA and Tukey's post-hoc tests were used to compare ALP and PO43− levels; generalized linear models were used to examine: ΔE/ΔE00/SMH/CSMH; and Kruskal–Wallis and Dunn's tests were used for ΔWID (α = 5%). The ALP activity was higher at pH 9, lower in H2O2-based mediums, and similar in both thickeners. The CD-spectra indicated denaturation of the enzyme upon contact with H2O2. The PO43− levels were higher after incorporating ALP, and the ΔE/ΔE00/ΔWID were comparable among bleached groups. SMH was lower after bleaching in Exp-H, while CSMH was highest in ALP-T. [ABSTRACT FROM AUTHOR]

Purpose: The addition of sodium trimetaphosphate (TMP) to fluoride (F) varnishes has been shown to be effective in controlling dental caries and erosive tooth wear. This study evaluated the amount of F and phosphate (P) released from fluoride varnishes containing micrometric or nano-sized sodium trimetaphosphate (TMPmicro or TMPnano, respectively). Methods: The experimental varnishes included a placebo formulation (no F or TMP), 2.5% NaF, 5% NaF, 5% NaF + 5% TMPmicro, 5% NaF + 5% TMPnano, 5%NaF + 2.5% TMPnano, and commercial varnish (Duraphat, 5% NaF). Varnishes were applied on polyester sheets (n=8/group) and alternately immersed in remineralizing or demineralizing solutions at 30, 60, 90, 120, 180, 240, 300, 360, 420, 540, 600, 720, 780, 960, 1200 and 1440 min after first immersion. F and P release were analyzed with an ion-selective electrode and colorimetrically, respectively. Data were analyzed by 2-way, repeated measures ANOVA and Student-Newman-Keuls' test (p<0.05). Results: Overall, varnishes containing TMPnano released significantly higher amounts of F in comparison with TMPmicro. Regarding the cumulative release of P, the varnishes containing TMP showed a constant increase up to 12 h. Conclusions: It was concluded that F release was significantly increased in TMPcontaining formulations, and that the nanosized TMP further enhanced such effects, without affecting phosphate release. [ABSTRACT FROM AUTHOR]

Phosphate, an essential ingredient in fertilizers and detergents used daily worldwide, is a finite resource that may be exhausted within 70 years, while improper phosphate waste disposal into aquatic environments will result in eutrophication. Despite some chemical-based methods, biological phosphorus removal using polyphosphate-accumulating organisms, such as microalgae, is a sustainable alternative to reclaim phosphate from wastewater before wastewater enters aquatic environments, preventing ecosystem damage while recovering the phosphate for industrial use. Moreover, polyphosphates have profound biological functions and biomedical applications, serving as an energy stock, drug delivery vesicles, coagulation factors, and antiviral agents depending on the length of the polyphosphate chain, showing inherent value in polyphosphate recovery. However, before this study, there were no sustainable and efficient approaches to synthesizing purified polyphosphates enriched with different lengths, which limited industrial and biomedical applications. Here, by leveraging the power of thermodynamic coupling and phase transitions, we established a one-pot, two-step multi-enzyme cascade (comprising creatine kinase and two polyphosphate kinases) to transform heterogeneous polyphosphate in microalgae biomass to insoluble long-chain polyphosphate 1300-mers, allowing for further purification in a single step. In the cascade reactions, introducing creatine as the high-energy P-shuttle enables controlled manipulation of the creatine kinase reaction direction via pH modulation, effectively circumventing the competition between the two polyphosphate kinase-mediated reactions. Finally, we optimized a thermo-digestion approach to transform polyphosphate 1300-mers into shorter polyphosphates enriched with a specific narrow length range. Therefore, the processes established here create a sustainable P bioeconomy platform to refine microalgal biomass for biotechnological use. [ABSTRACT FROM AUTHOR]

Inositol polyphosphates (IPs) are a group of inositol metabolites that act as secondary messengers for external signalling cues. They play various physiological roles such as insulin release, telomere length maintenance, cell metabolism, and aging. Inositol hexakisphosphate kinase 2 (IP6K2) is a key enzyme that produces 5-diphosphoinositol 1,2,3,4,6-pentakisphosphate (5-IP7), which influences the early stages of glucose-induced exocytosis. Therefore, regulation of IP6Ks may serve as a promising strategy for treating diseases such as diabetes and obesity. In this study, we designed, synthesised, and evaluated flavonoid-based compounds as new inhibitors of IP6K2. Structure-activity relationship studies identified compound 20s as the most potent IP6K2 inhibitor with an IC50 value of 0.55 μM, making it 5-fold more potent than quercetin, the reported flavonoid-based IP6K2 inhibitor. Compound 20s showed higher inhibitory potency against IP6K2 than IP6K1 and IP6K3. Compound 20s can be utilised as a hit compound for further structural modifications of IP6K2 inhibitors. [ABSTRACT FROM AUTHOR]

The cell wall of Candida yeast grown on presence of hexadecane as a sole carbon source undergoes structural and functional changes including the formation of specific supramolecular complexes—canals. The canals contain specific polysaccharides and enzymes that provide primary oxidization of alkanes. In addition, inorganic polyphosphate (polyP) was identified in Candida maltosa canals. The aim of the work was a comparative study of the features of cell walls and extracellular structures in yeast C. maltosa, C. albicans and C. tropicalis with special attention to inorganic polyphosphates as possible part of these structures when grown on the widely used xenobiotic hexadecane (diesel fuel). Fluorescence microscopy with DAPI has shown an unusual localization of polyP on the cell surface and in the exovesicles in the three yeast species, when growing on hexadecane. Electron-scanning microscopy showed that the exovesicles were associated with the cell wall and also presented in the external environment probably as biofilm components. Treatment of hexadecane-grown cells with purified Ppx1 polyphosphatase led to the release of phosphate into the incubation medium and the disappearance of polyP in vesicles and cell wall observed using microscopic methods. The results indicate the important role of polyP in the formation of extracellular structures in the Candida yeast when consuming hexadecane and are important for the design of xenobiotic destructors based on yeast or mixed cultures. [ABSTRACT FROM AUTHOR]

The chemical reactions and physical effects involved in the cessation of bone formation with age, the formation of blood and other cells in bone marrow plus the development of osteoporosis and the link of the latter to anaemia and diabetes are reconsidered with respect to the physical and biochemical conditions present in the human body. [ABSTRACT FROM AUTHOR]

The article presents results of the research on the influence of halloysite and its modified versions in a configuration with expandable graphite on thermal stability, integrity and intumescence of the fire-resistant paints for steel based on the epoxy resin and ammonium polyphosphate/pentaerythritol/melamine (APP/PER/MEL) system. The preliminary scanning electron microscope (SEM) analysis showed that halloysite modified with sulfuric acid (M2) has the best surface expansion. Nanotubes increased their volume and nanoplates were more delaminated. Temperature tests of the fire-resistant paints and subsequent SEM analysis confirmed these results, as a homogeneous structure with 50-fold multiplication was obtained for the sample with modified halloysite M2/expandable graphite, while the sample with pure halloysite/expandable graphite multiplied only 15-fold. Thermogravimetry/ differential scanning calorimetry (TG/DSC) analysis showed that the modified halloysite can significantly change the course of thermograms, even at low addition (7 wt%), and the mass loss can be reduced by up to about 13 wt%. The obtained results showed that the modified halloysite can successfully cooperate with expandable graphite and can be introduced into the intumescent system without deteriorating the physicochemical properties of the coating. [ABSTRACT FROM AUTHOR]

Phosphate (Pi) is a macronutrient, and Pi homeostasis is essential for life. Pi homeostasis has been intensively studied; however, many questions remain, even at the cellular level. Using Schizosaccharomyces pombe, we sought to better understand cellular Pi homeostasis and showed that three Pi regulators with SPX domains, Xpr1/Spx2, Pqr1, and the VTC complex synergistically contribute to Pi homeostasis to support cell proliferation and survival. SPX domains bind to inositol pyrophosphate and modulate activities of Pi-related proteins. Xpr1 is a plasma membrane protein and its Pi-exporting activity has been demonstrated in metazoan orthologs, but not in fungi. We first found that S. pombe Xpr1 is a Pi exporter, activity of which is regulated and accelerated in the mutants of Pqr1 and the VTC complex. Pqr1 is the ubiquitin ligase downregulating the Pi importers, Pho84 and Pho842. The VTC complex synthesizes polyphosphate in vacuoles. Triple deletion of Xpr1, Pqr1, and Vtc4, the catalytic core of the VTC complex, was nearly lethal in normal medium but survivable at lower [Pi]. All double-deletion mutants of the three genes were viable at normal Pi, but Δpqr1Δxpr1 showed severe viability loss at high [Pi], accompanied by hyper-elevation of cellular total Pi and free Pi. This study suggests that the three cellular processes, restriction of Pi uptake, Pi export, and polyP synthesis, contribute synergistically to cell proliferation through maintenance of Pi homeostasis, leading to the hypothesis that cooperation between Pqr1, Xpr1, and the VTC complex protects the cytoplasm and/or the nucleus from lethal elevation of free Pi. [ABSTRACT FROM AUTHOR]

Aims: Bacillus thuringiensis Y1 is a copper-tolerant bacterium that can serve as a model for the elucidation of the mechanism of energy metabolism under simulated copper stress. This study aimed to elucidate the effects of simulated copper stress on the genes associated with the biosynthesis of polyhydroxyalkanoates (PAH) and the metabolism of polyphosphates (PP). Methodology and results: The gene expression study involved the growth of the bacterium in nutrient broth supplemented with two concentrations of copper sulphate (0.4 mM and 0.8 mM), followed by RNA extraction and quantification of four and 11 genes associated with the metabolism of polyphosphate (PP) and polyhydroxyalkanoates (PAHs) respectively, using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Three genes associated with polyphosphate metabolism, which are polyphosphate kinase (ppk), exopolyphosphatase (ppx) and NAD kinase (ppnk), were all shown to be upregulated by both 0.4 mM and 0.8 mM copper, except for the 5'-nucleotidase (surE) gene that was downregulated under the second treatment. Among the 11 genes associated with the metabolism of polyhydroxyalkanoates, only the 3-ketoacyl-CoA-thiolase (phaA) gene was upregulated in both treatments and highly expressed in the second treatment; the majority were downregulated and repressed. Conclusion, significance and impact of study: The study demonstrated that copper induces the metabolism of polyphosphates in B. thuringiensis Y1 that serve as an alternative source of energy under copper stress. This model can be extended to the study of other species of Bacillus under environmental stress. [ABSTRACT FROM AUTHOR]

In cementitious systems, superplasticizers have two core purposes. On the one hand, they are used to lower the yield stress of a cement paste without changing the water to cement (w/c) ratio. On the other hand, they can reduce the w/c ratio without changing the yield stress. The relationship between slump flow and dosage of a superplasticizer containing cement paste can be described as an S‐curve. Below a critical dosage, the superplasticizer does not increase the flow. Above this dosage, the flow increases linearly until the saturation dosage is reached. Further addition of polymer will therefore not increase the fluidity of the cement paste. The minimum dosage which corresponds to an onset of increased flow compared to a dispersant free paste is referred to as the critical dosage. In this study, we analysed the dosage curve for three different polymers: a mela‐mine based (MFS), a polycarboxylate ether (PCE) and a polyphosphate ether (PPE) superplasticizer. The dosage curves of each superplasticizer were measured with a slump flow test at two different w/c ratios. To observe even small changes in the ultra‐low dosages, MFS was measured using a rheometer. We have specifically examined the areas defined as critical dosage and saturation dosage. We have found that these definitions need to be revised, not with regards to their values, but in terms of a proper understanding. [ABSTRACT FROM AUTHOR]