Phosphate Esterification Research Articles

Highly efficient adsorbent for removing uranium (VI) from water based on a novel phosphate esterification hyper-cross-linked polymer

There is a strong need for the development of effective uranium sorbents. Here, the Friedel-Crafts reaction was performed in a simple one-step manner followed by phosphate esterification to prepare porous hyper-cross-linked Bisphenol F (PHCP-BF) for prospective utilization in the removal of U(VI) from wastewater. PHCP-BF has pores with a size of 2.6 nm and a significant BET surface area (up to 387.31 m2/g). It was extensively investigated how a variety of environmental conditions (e.g., pH, contact time, temperature, etc.) affected the treatment results. In terms of adsorption capacity, uranium possessed a maximum of 120 mg/g (pH = 7), which is twice that of the original material HCP-BF (59.39 mg/g). According to the modeling results, with the Langmuir isotherm and a pseudo-second-order kinetic model, the data matched the sorption data very well. It was found that PHCP-BF possessed good selectivity for uranium, which was considerably greater than that of other co-existing metals. After three cycles, PHCP-BF still maintained a certain adsorption capacity. In light of several spectroscopic examinations, the mechanism of uranium removal by PHCP-BF is the chelated of P = O with U (VI). The results obtained suggest that PHCP-BF can be used effectively to remove uranium from water.

Bonding Behavior and Mechanism of U(VI) by Chemically Modified Deinococcus radiodurans

The goal of this study is to understand the role of various functional groups on the cell surface when the microorganisms are exposed to uranium (U(VI)). The biomass of Deinococcus radiodurans was subjected to chemical treatments to modify the carboxyl (-C=O), amino (-NH2), phosphate (-PO2−), and hydroxyl (-OH) groups, as well as the lipid fraction. The behavior and process of U(VI) biosorption by Deinococcus radiodurans were ascertained, followed by scanning electron microscopy (SEM) combined with energy disperse spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses. Carboxyl esterification and amino methylation deteriorated the removal efficiency by 8.0% and 15.5%, respectively, while lipid extraction, phosphate esterification, and hydroxyl methylation improved the removal efficiency by 11.7%, 8.7%, and 4.1%, respectively. The kinetic results revealed that uranium biosorption behavior by the raw and chemically modified biomass fitted well with the model of pseudo-second-order kinetic (R2 = 0.9949~0.9998). FTIR and SEM-EDS indicated that uranium initially bound with the raw and chemically modified Deinococcus radiodurans, which was probably controlled by ion exchange at the first stage, followed by complexation with the -C=O and -NH2 groups, which especially prefer to bond with P and O atoms on the -PO2− group.

Binding of boswellic acids to functional proteins of the SARS-CoV-2 virus: Bioinformatic studies.

Boswellic acids (BAs) have been shown to possess antiviral activity. Using bioinformatic methods, it was tested whether or not acetyl‐11‐keto‐β‐boswellic acid (AKBA), 11‐keto‐β‐boswellic acid (KBA), β‐boswellic acid (BBA), and the phosphorylated active metabolite of Remdesivir® (RGS‐P3) bind to functional proteins of SARS‐CoV‐2, that is, the replicase polyprotein P0DTD1, the spike glycoprotein P0DTC2, and the nucleoprotein P0DTC9. Using P0DTD1, AKBA and KBA showed micromolar binding affinity to the RNA‐dependent RNA polymerase (RdRp) and to the main proteinase complex Mpro. Phosphorylated BAs even bond in the nanomolar range. Due to their positive and negative charges, BAs and RGS‐P3 bond to corresponding negative and positive areas of the protein. BAs and RGS‐P3 docked in the tunnel‐like cavity of RdRp. BAs also docked into the elongated surface rim of viral Mpro. In both cases, binding occurred with active site amino acids in the lower micromolecular to upper nanomolar range. KBA, BBA, and RGS‐P3 also bond to P0DTC2 and P0DTC9. The binding energies for BAs were in the range of −5.8 to −6.3 kcal/mol. RGS‐P3 and BAs occluded the centrally located pore of the donut‐like protein structure of P0DTC9 and, in the case of P0DTC2, RGS‐P3 and BAs impacted the double‐wing‐like protein structure. The data of this bioinformatics study clearly show that BAs bind to three functional proteins of the SARS‐CoV‐2 virus responsible for adhesion and replication, as does RGS‐P3, a drug on the market to treat this disease. The binding effectiveness of BAs can be increased through phosphate esterification. Whether or not BAs are druggable against the SARS‐CoV‐2 disease remains to be established.

Gelation, flame retardancy, and physical properties of phosphorylated microcrystalline cellulose aerogels

Flame-retardant bio-based cellulose aerogels, with abundant renewable sources, are considered as promising sustainable heat-insulation alternatives to conventional petroleum-based foams. An environmentally friendly method was employed to fabricate phosphorylated microcrystalline cellulose (PMCC) aerogel through the gelation of PMCC/H2O dispersion and freeze-drying of PMCC hydrogel. The dispersion stability of PMCC and its readiness to undergo gelation in the aqueous phase were enhanced by increasing the phosphorous content via phosphorylation, thereby effectively weakening the strong intra- and intermolecular hydrogen-bond interactions of the cellulose chains. The morphology of the PMCC aerogel changed from a short rod-shaped and sheet-like aggregation of a three-dimensional skeleton structure to a mostly sheet-like aggregation of a three-dimensional structure with increased phosphate esterification. Remarkably, PMCC aerogels exhibited improved flame retardancy and superior suppression of toxic gas, compared to MCC. This is attributable to the synergic effect of phosphate dehydration, catalytic carbonization, and protection of the aerogel network structure.

Synthesis of a phosphorus˗nitrogen flame retardant endowing cotton with high whiteness and washability

Cotton is the seed fiber of the Gossypium plant (from the Malvaceae family), which is one of the most important crops worldwide and is suitable for the application in clothes, furniture, and industrial fabrics areas. Combustible cotton easily triggers fire hazard. Thus, a phosphorous˗nitrogen flame retardant, ammonium salt of tris˗(hydroxymethyl)˗aminomethane˗penta(methylphosphonic acid) (ATPMPA) was synthesized to produce fire˗retardant cotton. The ATPMPA structure was characterized by nuclear magnetic resonance (1H NMR, 13C NMR, and 31P NMR) spectroscopy. ATPMPA flame˗retardant cotton was prepared by phosphate esterification between ATPMPA and the ˗OH groups of cotton cellulose. Scanning electron microscopy verified that the surface of the treated cotton fiber was not obviously changed. The flame retardantcy of cotton was tested using the LOI, vertical burning and cone calorimetry. The results revealed that the LOIs of the control cotton and treated cotton fabrics increased from 18.4% to 40.8%, 42.4%, and 43.6% after treated with 20 wt%, 30 wt% and 40 wt% flame retardant, respectively. After 50 laundering cycles (LCs), the LOIs of the treated cotton fabrics only decreased to 26.7%, 30.8%, and 32.3%, respectively, indicating that treated cottons obtained the superior flame retardancy and excellent washing resistance. Thermogravimetry (TG) analysis showed that the charring ability of the treated cotton was markedly improved. TG-IR result of treated cotton indicated that the decomposition temperature and the amount of volatile matter produced by the flame-retardant cotton were lower than that of control cotton. The whiteness of treated cotton sustains well.

Phosphorylated Boron Nitride Nanosheets as Highly Effective Barrier Property Enhancers

Hexagonal boron nitride (hBN) with outstanding impermeability and resistivity seems to hold promise as a long-term corrosion barrier for metals. However, the high-yield production of hBN still remains a key challenge. Herein, we provide a scalable exfoliation technique to scalable synthesis of hydroxylated boron nitride nanosheets (HBNNS). Then phosphorylated boron nitride (PBNNS) was prepared through in situ phosphate esterification between HBNNS and phosphoric acid. The PBN coatings were fabricated by electrophoretic deposition (EPD) from PBNNS suspensions for metal protection. The excellent corrosion resistance of PBNNS-EPD layers was attributed to the superior barrier property and formed passivation film from PBNNS.

Reinforcement of phosphorylated graphene oxide on the anticorrosive properties of waterborne acrylate-epoxy resin coatings

Phosphorylated graphene oxide (PedGO) was synthesized through the in-situ phosphate esterification method with urea as catalyst and then embed into waterborne acrylate-epoxy resin emulsion (AE) coating to modify the coating. The TEM and AFM indicated that phosphate was uniformly decorated on GO sheets, forming a large phosphorylated graphene oxide sheets. The PedGO improved the water vapor permeability and the coating adhesion strength after 30 days of immersion in 3.5% NaCl of AE coatings, respectively. Electrochemical impedance spectroscopy measurements (EIS) revealed that the PedGO-modified AE (PedGO/AE) was an outstanding barrier against corrosive media compared with AE or GO-modified AE (GO/AE). Scratch tests also showed that the corrosion-promotion effect of PedGO in AE was inhibited. The enhanced corrosion protection performance was observed because on the one hand the PedGO can greatly prolonged the diffusion pathway of corrosive media in the coating matrix; on the other hand the organic phosphate on the PedGO formed the passivation membrane with metal ions by chelation in the corrosion region, which can prevented the contact of corrosive medium and metal.

Chemically modified surface functional groups of Alcaligenes sp. S-XJ-1 to enhance its demulsifying capability.

Cell-surface functional groups (amino, carboxyl, hydroxyl, as well as phosphate) were chemically modified in various ways to enhance the demulsification capability of the demulsifying bacteria Alcaligenes sp. S-XJ-1. Results demonstrated that the demulsifying activity was significantly inhibited by amino enrichment with cetyl trimethyl ammonium bromide, amino methylation, hydroxyl acetylation, and phosphate esterification, but was gradually promoted by carboxyl blocking with increasing the extents of esterification. Compared with the raw biomass, an optimal esterification of carboxyl moieties enhanced the demulsification ratio by 26.5% and shortened the emulsion half-life from 24 to 8.8h. The demulsification boost was found to be dominated by strengthened hydrophobicity (from 53° to 74°) and weakened electronegativity (from -34.6 to -4.3mV at pH7.0) of the cell surface, allowing the rapid dispersion and adsorption of cells onto the oil-water interface. The chemical modification of the functional groups on the biomass surface is a promising tool for the creation of a high-performance bacterial demulsifier.

Mechanism of electron transport during thiosulfate oxidation in an obligately mixotrophic bacterium Thiomonas bhubaneswarensis strain S10 (DSM 18181T).

This study describes the thiosulfate-supported respiratory electron transport activity of Thiomonas bhubaneswarensis strain S10 (DSM 18181T). Whole-genome sequence analysis revealed the presence of complete sox (sulfur oxidation) gene cluster (soxCDYZAXB) including the sulfur oxygenase reductase (SOR), sulfide quinone reductase (SQR), sulfide dehydrogenase (flavocytochrome c (fcc)), thiosulfate dehydrogenase (Tsd), sulfite dehydrogenase (SorAB), and intracellular sulfur oxidation protein (DsrE/DsrF). In addition, genes encoding respiratory electron transport chain components viz. complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex III (ubiquinone-cytochrome c reductase), and various types of terminal oxidases (cytochrome c and quinol oxidase) were identified in the genome. Using site-specific electron donors and inhibitors and by analyzing the cytochrome spectra, we identified the shortest thiosulfate-dependent electron transport chain in T. bhubaneswarensis DSM 18181T. Our results showed that thiosulfate supports the electron transport activity in a bifurcated manner, donating electrons to quinol (bd) and cytochrome c (Caa 3 ) oxidase; these two sites (quinol oxidase and cytochrome c oxidase) also showed differences in their phosphate esterification potential (oxidative phosphorylation efficiency (P/O)). Further, it was evidenced that the substrate-level phosphorylation is the major contributor to the total energy budget in this bacterium.

Biosorption performances of raw and chemically modified biomasses from Perenniporia subacida for heterocycle dye Neutral Red

Biosorption performances of raw and chemically modified biomasses (treated with (i) lipid removal, (ii) phosphate esterification, (iii) amine methylation, and (iv) amine propylamination) from white rot fungus Perenniporia subacida were investigated for heterocycle dye Neutral Red removal. Better dye uptake was obtained at constant temperature and agitation speed with the optimum variables like initial pH at 3.0, initial dye concentration at 50 mg/L, surfactant Tween 80 at 2.5% (V/V), inorganic salt NaCl at 0.1 M, and first 60 min of reaction time. A comparison of the different isotherm models indicated that the biosorption process by the fungal biomass followed the Langmuir isotherm model. The kinetic data could be well described by the pseudo-second-order model. Calculated thermodynamic parameters of biosorption indicated the exothermic and spontaneous process. Additionally, the modification of biomass with amine propylamination increased the biosorption capability of Neutral Red dye about 1.36-fold of the raw fungal biomass. These observations were characterized by FT-IR, SEM, and X-ray diffraction, respectively.

Alternative synthetic tools to phospho-specific antibodies for phosphoproteome analysis: progress and prospects

Signal transduction cascades in living systems are often controlled via post-translational phosphorylation and dephosphorylation of proteins. These processes are catalyzed in vivo by kinase and phosphatase enzymes, which consequently play an important role in many disease states, including cancer and immune system disorders. Current techniques for studying the phosphoproteome (isotopic labeling, chromatographic techniques, and phosphospecific antibodies), although undoubtedly very powerful, have yet to provide a generic tool for phosphoproteomic analysis despite the widespread utility such a technique would have. The use of small molecule organic catalysts that can promote selective phosphate esterification could provide a useful alternative to current state-of-the-art techniques for use in, e.g., the labeling and pull-down of phosphorylated proteins. This report reviews current techniques used for phosphoproteomic analysis and the recent use of small molecule peptide-based catalysts in phosphorylation reactions, indicating possible future applications for this type of catalyst as synthetic alternatives to phosphospecific antibodies for phosphoproteome analysis.

Immobilization of Rhizopus oryzae in a modified polyvinyl alcohol gel for L(+)-lactic acid production

The production of L(+)-lactic acid (LA) by Rhizopus oryzae immobilized in polyvinyl alcohol (PVA) was investigated. To decrease diffusional resistance, we modified the PVA gel through the addition of sodium alginate and phosphate esterification. The production of L(+)-LA improved notably in the immobilized Rhizopus oryzae. Maximum L(+)-LA production (106.27 g/L), with a yield of 73.1 % and rate of 2.95 g/L·h, was obtained at a temperature of 38 °C, 6 % PVA, and 0.8 % sodium alginate. The immobilized R. oryzae was stable in 14 serial-batch cultures using non-growth medium. The immobilized beads also displayed good tolerance to low temperature and long-term storage at 4 °C with the preservation of biochemical properties.

Proton-conducting electrolyte film of double-decker-shaped polyhedral silsesquioxane containing covalently bonded phosphonic acid groups

As described in this paper, phosphonic-acid-containing double-decker-shaped polyhedral silsesquioxane (PHOS-DDSQ) was synthesized and the proton conductivity of the PHOS-DDSQ cast film was studied under humid and non-humid conditions. To synthesize PHOS-DDSQ, double-decker-shaped polyhedral silsesquioxane (DDSQ) was initially reacted with di(ethylene glycol) (DEG) vinyl ether using hydrosilylation reaction to attach four DEG units to one DDSQ (4DEG-DDSQ). Subsequently, a phosphate esterification of hydroxyl groups in 4DEG-DDSQ was carried out using POCl3. NMR, XPS, and MALDI-TOF MS spectra and titration measurements revealed that the phosphate esterification connected two DEG units to form a crown-ether-like structure. This structure prevents hydrolysis of the phosphate ester bond. PHOS-DDSQ showed high thermal stability, with decomposition temperature exceeding 220 °C, because of its inorganic DDSQ core. A uniform film of PHOS-DDSQ can be fabricated by drop casting. The cast film showed high proton conductivity (0.12 S cm−1) under humid conditions, which is comparable to that of a Nafion® membrane. Moreover, the cast film offered good proton conductivity under non-humid conditions (3.6 × 10−4 S cm−1 at 170 °C). The conductivity and thermal stability indicate that PHOS-DDSQ is a good candidate for use as a proton-conductive membrane in hydrated type fuel cells as well as fuel cells operated at intermediate temperatures (100–200 °C) under non-humid conditions.

Isolation and characterization of the diastereoisomers of a series of phosphate-ethylated dinucleoside monophosphates

Internucleotide phosphate esterification is a common reaction of many potent carcinogenic alkylating agents. It can give rise to two stereochemically distinct molecules about a triesterified phosphorus atom. The eight individual diastereoisomers derived from phosphate ethylation of d-ApT, d-CpT, d-GpT, and d-TpT were prepared from o-chlorophenyl phosphotriester intermediates and isolated by reverse-phase HPLC. Each pair of isomers, together with its parent analog, was examined by variable temperature circular dichroism. The results are interpreted in terms of secondary structure changes from which the absolute configurations of the ethylated phosphate groups can be inferred. These configurational assignments were confirmed by 31P NMR.

Energy coupling mechanisms in host-grown Mycobacterium lepraemurium.

Energy coupling mechanisms of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata were investigated. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of generated NADH, added NADH, and succinate yielding P/O ratios of approximately 0.8, 0.6, and 0.4, respectively. Ascorbate oxidation alone or in the presence of cytochrome c or N,N,N',N'-tetramethyl-p-phenylenediamine was not coupled to ATP synthesis. The oxidative phosphorylation was completely uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonylcyanide phenylhydrazone, dicumarol, and gramicidin at concentrations which did not cause any inhibition of oxygen uptake. While the NADH oxidation and associated phosphate esterification was markedly sensitive to rotenone and other flavoprotein inhibitors, these inhibitors had no effect, however, on the phosphorylation coupled to succinate oxidation. The respiratory chain inhibitors such as antimycin A or 2-n-heptyl-4-hydroxyquinoline-N-oxide, and cyanide were the potent inhibitors of the phosphorylation associated with the oxidation of NADH and succinate. The ATP formation coupled to the oxidation of NADH and succinate was also inhibited by oligomycin as well as by the thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide. The results indicated that NADH and succinate oxidation by in vivo grown M. lepraemurium was mediated by oxidative enzymes involving first and second energy coupling sites.

NADH-Linked oxidative phosphorylation inNitrobacter agilis

A particulate cell-free fraction (144,000-X-g pellet) fromNitrobacter agilis catalyzes the acrobic or anaerobic oxidation of NADH. Phosphorylation coupled to the aerobic oxidation of NADH yields P/O ratios of 1.1. The net formation of ATP coupled to the anaerobic oxidation of NADH by nitrate yields P/NO3 ratios of 0.7. Phosphate esterification is uncoupled by carbonylcyanide-m-chlorophenyl-hydrozone and is sensitive to inhibitors of the electron transport system.

The effect of high sugar intake on the esterification of dihydroxyacetone phosphate by rat liver microsomes

Rat liver microsomes were used as an enzyme source to study dietary-induced changes in the rate of dihydroxyacetone phosphate esterification. Rats were fed (1) 75% glucose or fructose diets for various time intervals, or (2) fed a fractose diet for six days and then a chow diet. Both the glucose and fructose diets produced a 2--3-fold increase in total and neutral glycerolipid formation from dihydroxyacetone phosphate measured in the presence of ATP, palmitate, CoA, and NADH. The increased rate of dihydroxyacetone phosphate esterification and a simultaneous rise in serum triglyceride level in rats fed fructose was rapidly reversed when chow was substituted for the fructose. The results indicate that an increased rate of dihyroxyacetone phosphate esterification may contribute to the acceleration of endogenous glycerolipid biosynthesis noted under these dietary conditions.

Electron Transport and Coupled Energy Generation in Pseudomonas saccharophila

The respiratory chain system of heterotrophically grown Pseudomonas saccharophila contained cytochromes of the b, c, a, and o types and also the NADH and succinate oxidase enzyme systems. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of NADH, succinate, and ascorbate (plus cytochrome c). The P/O ratios were in the range of 1.00 for generated NADH, 0.29 for added NADH, 0.50 for succinate, and 0.25 for ascorbate (plus cytochrome c).The oxidative phosphorylation was uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonyl cyanide phenylhydrazone, and dicumarol without any inhibition of oxygen consumption. Phosphorylation coupled to NADH oxidation was completely inhibited by the flavoprotein inhibitors such as rotenone, amytal, and atabrine; these inhibitors had no effect, however, on the ATP synthesis associated with succinate oxidation. Antimycin A or 2-n-nonyl-4-hydroxyquinoline-N-oxide as well as cyanide or azide at low concentrations completely inhibited the phosphate esterification coupled to the oxidation of NADH or succinate, but had little or no effect on the oxygen consumption. Relatively higher concentrations of oligomycin were required for a complete inhibition of the electron-transport-linked ATP formation.

Effect of Antimycin A on Photosynthesis of Intact Spinach Chloroplasts

Low concentrations (0.5-10 mum) of antimycin A were shown to increase the rate of CO(2) fixation, O(2) evolution and inorganic phosphate esterification in intact spinach (Spinacia oleracea) chloroplasts. The increase was highest when the light intensity was saturating. Stimulation was independent of the bicarbonate concentration and was accompanied by an enhancement in the synthesis of glycerate 3-phosphate with a decrease in dihydroxyacetone phosphate. The antibiotic decreased the Michaelis constant of the chloroplast but not of ribulose 1,5-diphosphate carboxylase for bicarbonate. It was suggested that antimycin A is affecting that portion (outer envelope) of the intact chloroplast which contains the enzyme mechanism for controlling the pace of CO(2) fixation.

Energy conversion in autotrophically grown Pseudomonas saccharophila.

1 Studies were undertaken to investigate the energy coupling mechanism in autotrophically grown Pseudomonas saccharophila. The cell-free extracts from Pseudomonas saccharophila contained flavoproteins and cytochromes of b, c, a, and o type. 2 Added NADH was oxidized rapidly but it was not coupled to phosphorylation. The oxidation of generated NADH, was mediated, however, by the flavoprotein and cytochrome systems and yielded P/O ratios ranging from 0.86 to 1.23. 3 The oxidation of hydrogen was mediated by the cytochrome systems but NAD+ was not involved; H2 oxidation yielded P/O ratios between 0.45 and 0.73. 4 Succinate oxidation resulted in a P/O ratio of 0.15 while ascorbate oxidation was not coupled to phosphorylation. 5 The phosphorylation coupled to the oxidation of hydrogen, NADH or succinate was completely uncoupled by various uncouplers of oxidative phosphorylation and phosphate esterification associated with the oxidation of NADH was quite sensitive to the flavoprotein inhibitors such as rotenone, amytal, and atabrine. These inhibitors had no effect, however, on the phosphorylation coupled to hydrogen or succinate oxidation. 6 The ATP formation associated with the oxidation of hydrogen, NADH or succinate was inhibited by antimycin A or 2-n-nonyl-4-hydroxyquinoline-N-oxide as well as by cyanide or azide.