Low-temperature thermocatalytic removal of formaldehyde in air using copper manganite spinels.

The removal of formaldehyde (FA) is vital for indoor air quality management in light of its carcinogenic propensity and adverse environmental impact. A series of copper manganite spinel structures (e.g., CuMn2O4) are prepared using the sol-gel combustion method and treated with reduction or oxidation pretreatment at 300 °C condition. Accordingly, CuMn2O4-O ("O" suffix for oxidation pre-treatment in air) is identified as the best performer to achieve 100% conversion (XFA) of FA (50 ppm) at 90 °C; its performance, if assessed in terms of reaction kinetic rate (r) at XFA = 10%, is 5.02E-03 mmol g-1 h-1. The FA removal performance increases systematically with decreases in flow rate, FA concentration, and relative humidity (RH) or with increases in bed mass. The reaction pathways and intermediates of FA catalytic oxidation on CuMn2O4-A are studied with density functional theory simulations, temperature-programmed characterization experiments, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The synergistic combination of large quantities of adsorbed oxygen (OA) species and oxidized metal species (e.g., Cu2+) contribute to the enhanced catalytic performance of CuMn2O4-O to oxidize FA into CO2 with the reaction intermediates of H2CO2 (DOM), HCOO-, and CO. The present study is expected to provide valuable insights into the thermocatalytic oxidation of FA over spinel CuMn2O4 materials and their catalytic performances in relation to the key process variables.

Photocatalytic removal of organic dye using green synthesized zinc oxide coupled cadmium tungstate nanocomposite under natural solar light irradiation.

In this work, zinc oxide coupled cadmium tungstate (ZnO-CT) was prepared as a nano-photocatalyst through a green synthesis route using lemon leaf extract and characterized based on diverse microscopic and spectroscopic techniques. To explore the applicabilties of the prepared nanocomposite (NC), its photocatalytic activity has been investigated against Congo red (CR) dye under natural solar light irradiation conditions. ZnO- CT nano-photocatalyst showcases 97% photocatalytic degradation of the CR after 90 min of natural solar light irradiation with quantum yield of 1.16 × 10-8 molecules photon-1. The ZnO-CT NC has shown the enhanced photocatalytic degradation performance against CR when compared to its pristine forms (e.g., ZnO (70%) or CT (44%)). According to the free radical trapping and quenching experiments, the photocatalytic activity of ZnO-CT NC appears to be driven efficiently by superoxide and hydroxyl radicals. The photocatalytic degradation kinetics for CR dye was also studied using the pseudo-first-order, diffusional, and Singh models. The high photocatalytic activity of ZnO-CT NC can be accounted for by the presence of electron-withdrawing functional groups like acids (-COOH) and aldehydes (-CHO) on its surface which helped maintain the prolonged recombination of charge carriers and enhanced stability of ZnO-CT (with moderately low leaching rate of cadmium ions (∼2-5%)).

2.09†ŠResolution structure of E. coli HigBA toxin-antitoxin complex reveals an ordered DNA-binding domain and intrinsic dynamics in antitoxin.

The toxin-antitoxin (TA) systems are small operon systems that are involved in important physiological processes in bacteria such as stress response and persister cell formation. Escherichia coli HigBA complex belongs to the type II TA systems and consists of a protein toxin called HigB and a protein antitoxin called HigA. The toxin HigB is a ribosome-dependent endoribonuclease that cleaves the translating mRNAs at the ribosome A site. The antitoxin HigA directly binds the toxin HigB, rendering the HigBA complex catalytically inactive. The existing biochemical and structural studies had revealed that the HigBA complex forms a heterotetrameric assembly via dimerization of HigA antitoxin. Here, we report a high-resolution crystal structure of E. coli HigBA complex that revealed a well-ordered DNA binding domain in HigA antitoxin. Using SEC-MALS and ITC methods, we have determined the stoichiometry of complex formation between HigBA and a 33 bp DNA and report that HigBA complex as well as HigA homodimer bind to the palindromic DNA sequence with nano molar affinity. Using E. coli growth assays, we have probed the roles of key, putative active site residues in HigB. Spectroscopic methods (CD and NMR) and molecular dynamics simulations study revealed intrinsic dynamic in antitoxin in HigBA complex, which may explain the large conformational changes in HigA homodimer in free and HigBA complexes observed previously. We also report a truncated, heterodimeric form of HigBA complex that revealed possible cleavage sites in HigBA complex, which can have implications for its cellular functions.

An efficient tool for the continuous monitoring on adsorption of sub-ppm level gaseous benzene using an automated analytical system based on thermal desorption-gas chromatography/mass spectrometry approach.

It became an important task to effectively adsorb volatile organic compounds (VOCs) at or near real-world levels for efficient control of airborne pollution in ambient environments. Nonetheless, most studies carried out previously for the control of VOCs are confined to significantly polluted conditions (e.g., >100 ppm) that are far different from real-world or ambient conditions. To help acquire the meaningful data for the adsorptive removal of VOCs at near real-world levels, a new approach was designed and implemented to measure adsorption of gaseous benzene (as a representative or model VOC) at trace-level quantities (as low as 0.14 ng (0.43 ppb) for a 100 mL sample) using activated carbon (sieved to 212 µm mesh size) as a model sorbent. With the aid of a thermal desorption-gas chromatography/mass spectrometry system, the key adsorption performance metrics (such as 10% breakthrough volume (10% BTV) points: 10% as the key reference) were determined: 1018 L atm g-1 at 0.1 ppm benzene with the corresponding partition coefficient of 3.85 mol kg-1 Pa-1. If the adsorption capacity values (at 10% BTV) are compared across the varying concentration levels of benzene, the maximum value of 1.07 mg g-1 was observed at 1 ppm benzene (within the concentration range selected in this work). As such, it was possible to quantitatively assess the sorbate-sorbent interactions at significantly low concentrations of VOCs that actually prevail under the near real-world conditions.

Evidence of inter-species swing adsorption between aromatic hydrocarbons.

In this research, the competitive adsorption characteristics between aromatic hydrocarbons were investigated. It is well-known that an industrial effluent may contain a mixture of pollutants. The composition of effluents is usually highly variable in nature to depend upon the feedstock. Hence, one of the pollutants that is present in larger amounts may have the potential to dominate the sorption processes. Although many studies have investigated the competitive adsorption of volatile organic compounds (VOCs) onto activated carbon (AC) in detail, little is known about how the overall process is influenced when a fresh incoming VOC molecule encounters a sorbent bed pre-loaded with other VOCs. Consequently, the objective of the present study was to investigate the stability of pre-adsorbed VOC molecules in the presence of other potentially competitive VOCs in the influent stream. In this regard, the sorbent bed of AC was first preloaded with benzene (50 ppm (0.16 mg L-1)) and subsequently challenged by either high purity nitrogen or a stream of xylene (at 10, 50, or 100 ppm (0.043, 0.22, or 0.43 mg L-1)). The desorption rate of preloaded benzene and uptake rate of challenger xylene were assessed simultaneously. The maximum desorption rates of benzene (Rb) against two challenge scenarios (e.g., 100 ppm (0.43 mg L-1) xylene and pure N2) were very different from each other, i.e., 663 vs. 257 g kg-1 h-1, and their final benzene recoveries were 84% and 42%, respectively. The initially high desorption rate for the former quickly decreased with decreasing benzene residual capacity (C, mg g-1). Interestingly, the adsorption capacity of xylene increased considerably after the preloading of benzene (relative to no preloading). As such, 10% breakthrough volumes (BTV10) of 100, 50, and 10 ppm (0.43, 0.22, and 0.043 mg L-1) xylene challenge scenarios increased significantly from 100 to 186, 43.4 to 694, and 600 to 1000 L atm g-1, respectively. The prevalent mechanisms were analyzed using density functional theory (DFT)-based modelling approaches. The results demonstrated effective replacement of pre-adsorbed molecules with weaker affinity (e.g., benzene) when challenged by molecules with stronger affinity (e.g., xylene) toward the sorbent; this was accompanied by noticeable synergistic enhancement in the adsorption capacity of the latter.

Insights into the storage stability of ammonia in polyester aluminum bags.

A list of gaseous odorants such as ammonia (and hydrogen sulfide) are generally collected using rigid containers or flexible bags for quantitative analysis. The aim of this investigation was to assess the stability of polyester aluminum bags used for gaseous ammonia sampling and storage. To this end, ammonia standards were prepared at two concentration levels of low (7.8 ppm) and high concentrations (39 ppm) and stored in the polyester ammonia bags for durations of 0, 1, 2, 4, and 6 days. These samples were then analyzed at each interval by an impinger-based indophenol method utilizing a spectrophotometer. At each pre-set period, three different mass loadings of ammonia samples were collected from the storage bag to obtain response factors (RF) for comparison between different elapsed times set for the storage. Subsequently, the relative recovery values for each interval were computed by dividing the RF for each sampling day by that of the 0th day. The relative recovery values for low and high concentration standards decreased with increasing storage time as 82.9% (day 1) to 36% (day 6) and 89.9% (day 1) to 59.7% (day 6), respectively. As such, the potentially superior recovery of ammonia from polyester aluminum bags was demonstrated (e.g., relative to other storage options introduced previously) to support its practical merit as storage media.

The retrograde adsorption phenomenon at the onset of breakthrough and its quantitation: An experimental case study for gaseous toluene on activated carbon surface.

The adsorption dynamics of common solid sorbents against various pollutant species are yet poorly understood with respect to the retrograde phenomenon in which the relationship between breakthrough vs. pulled volume is characterized by an early unusual trend (initial increase followed by a decrease to a minimum) and by a normal trend of finally increasing to 100% (or equilibrium). If such trend is expressed in terms of the partition coefficient (PC), a reversed trend of adsorption processes becomes more evident. Retrograde has been previously observed in the initial breakthrough (<10%) isotherms in continuous flow gas-phase adsorption processes. However, retrograde has been neglected/overlooked and not discussed at all in the main stream literature even when it is explicitly observed from isotherm datasets. To properly describe the various aspects of such process, a stop-flow technique was developed to measure the adsorption isotherm of a model volatile organic compound (i.e., toluene in this study) onto a commercial low-cost sorbent (activated carbon: AC). Accordingly, a 10% breakthrough volume of 762 L atm g-1 (corresponding adsorption capacity of 142 mg g-1) was determined (at an inlet stream 5 Pa of toluene in 1 atm of N2 and 5 mg of AC). This automated method was effective to generate a detailed breakthrough profile at high stream-flow rates (or high space velocities) to specifically detect the retrograde phenomenon at the breakthrough onset. This study offers a practical approach towards establishing an in-depth monitoring protocol for the rare retrograde phenomenon.

Adsorption properties of advanced functional materials against gaseous formaldehyde.

Intense efforts have been made to eliminate toxic volatile organic compounds (VOCs) in indoor environments, especially formaldehyde (FA). In this study, the removal performances of gaseous FA using two metal-organic frameworks, MOF-5 and UiO-66-NH2, and two covalent-organic polymers, CBAP-1 (EDA) and CBAP-1 (DETA), along with activated carbon as a conventional reference material, were evaluated. To assess the removal capacity of FA under near-ambient conditions, a series of adsorption experiments were conducted at its concentrations/partial pressures of both low (0.1-0.5 ppm/0.01-0.05 Pa) and high ranges (5-25 ppm/0.5-2.5 Pa). Among all tested materials at the high-pressure region ㅐ (e.g., at 2.5 ppm FA), a maximum adsorption capacity of 69.7 mg g-1 was recorded by UiO-66-NH2. Moreover, UiO-66-NH2 also displayed the best 10% breakthrough volume (BTV10) of 534 L g-1 (0.5 ppm FA) to 2963 L g-1 (0.1 ppm FA). In contrast, at the high concentration test (at 5, 10, and 25 ppm FA), the maximum BTV10 values were observed as: 137 (UiO-66-NH2), 144 (CBAP-1 (DETA)), and 36.8 L g-1 (CBAP-1 (EDA)), respectively. The Langmuir isotherm model was observed to be a better fit of the adsorption data than the Freundlich model under most of the tested conditions. The superiority of UiO-66-NH2 was attributed to the van der Waals interactions between the linkers (framework) and the hydrocarbon "tail" (FA) coupled with interactions between its open metal sites and the FA carbonyl groups. This study demonstrated the good potential of these advanced functional materials toward the practical removal of gaseous FA in indoor environments.

Biodegradation of methylene blue dye in a batch and continuous mode using biochar as packing media.

Bacterial species for metabolizing dye molecules were isolated from dye rich water bodies. The best microbial species for such an application was selected amongst the isolated bacterial populations by conducting methylene blue (MB) batch degradation studies with the bacterial strains using NaCl-yeast as a nutrient medium. The most suitable bacterial species was Alcaligenes faecalis (A. faecalis) according to 16S rDNA sequencing. Process parameters were optimized and under the optimum conditions (e.g., inoculum size of 3 mL, temperature of 30 °C, 150 ppm, and time of 5 days), 96.2% of MB was removed. Furthermore, the effectiveness for the separation of MB combining bio-film with biochar was measured by a bio-sorption method in a packed bed bioreactor (PBBR) in which microbes was immobilized. The maximum MB removal efficiencies, when tested with 50 ppm dye using batch reactors containing free A. faecalis cells and the same cells immobilized on the biochar surface, were found to be 81.5% and 89.1%, respectively. The PBBR operated in continuous recycle mode at high dye concentration of 500 ppm provided 87.0% removal of MB through second-order kinetics over 10 days. The % removal was found in the order of PBBR>Immobilized batch>Free cell. The standalone biochar batch adsorption of MB can be described well by the pseudo-second order kinetics (R2 ≥ 0.978), indicating the major contribution of electron exchange-based valence forces in the sorption of MB onto the biochar surface. The Langmuir isotherm suggested a maximum monolayer adsorption capacity of 4.69 mg g-1 at 40 °C which was very close to experimentally calculated value (4.97 mg g-1). Moreover, the Casuarina seed biochar was reusable 5 times.

Titanium dioxide-supported mercury photocatalysts for oxidative removal of hydrogen sulfide from the air using a portable air purification unit.

Photocatalytic removal of gaseous hydrogen sulfide (H2S) has been studied through the control of key process variables using a prototype air purifier (AP) fabricated with titanium dioxide (TiO2)-supported mercury. The performance of Hg/TiO2 systems, prepared with different Hg mass proportions over TiO2 (such as 0.1%, 1%, 2%, and 5%), is measured against 5 ppm H2S at 160 L min-1 under UV irradiation. Accordingly, their removal efficiency (RE) values after 360 s are 40.3%, 74.8%, 99.3%, and 99.9%, respectively (relative to 33.5% of AP (TiO2)). An AP with a 2% Hg/TiO2 unit achieves a clean air delivery rate of 32 L min-1 with kinetic reaction rate (r (at 10% RE)) of 0.774 mmol h-1 g-1, quantum yield of 2.19E-02 molecules photon-1, and space-time yield of 1.46E-04 molecules photon-1 mg-1. The superior photocatalytic performance of Hg/TiO2 is supported by superoxide anion and hydroxyl radicals formed in dry air and humid nitrogen (N2) environments, respectively. A density functional theory simulation suggests that the presence of oxygen vacancies should promote the disparities in the electronic structure to subsequently affect the reaction pathways and energetics. The presence of moisture enhances the robust formation of a mercury-OH bond to favorably yield ß-mercury sulfide from H2S.

Benzene Oxidation in Air by an Amine-Functionalized Metal-Organic Framework-Derived Carbon- and Nitrogen-Loaded Zirconium Dioxide-Supported Platinum Catalyst.

To learn more about the behavior of amine (NH2)-functionalized metal-organic framework (MOF)-derived noble metal catalysts in the removal of aromatic volatile organic compounds in air, benzene oxidation at low temperatures has been investigated using 0.2-, 0.8-, and 1.5%-platinum (Pt)/Universitetet i Oslo (UiO)-66-NH2. The benzene conversion (XB) of x%-Pt/UiO-66-NH2-R under dry conditions (175 °C) was 23% (x = 0.2%) < 52% (x = 0.8%) < 100% (x = 1.5%): 'R' suffix denotes reduction pretreatment using a hydrogen (10 vol %) and nitrogen mixture at 300 °C for the generation of metallic Pt (Pt0) sites and simultaneous partial MOF decomposition into carbon- and nitrogen-loaded zirconium dioxide. The prominent role of reduction pretreatment was apparent in benzene oxidation as 1.5%-Pt/UiO-66-NH2 did not exhibit catalytic activity below 175 °C (dry condition). The promotional role of moisture in benzene oxidation by 1.5%-Pt/UiO-66-NH2-R was evident with a rise in the steady-state reaction rate (r) at 110 °C (21 kPa molecular oxygen (O2)) from 1.3 × 10-3 to 5.0 × 10-3 µmol g-1 s-1 as the water (H2O) partial pressure increased from 0 to 1.88 kPa. In contrast, the activity was lowered with increasing RH due to catalyst poisoning by excess moisture (r (110 °C) of 6.6 × 10-04 µmol g-1 s-1 at 2.83 kPa H2O (21 kPa O2)). Kinetic modeling suggests that XB proceeds through the Langmuir-Hinshelwood mechanism on the Pt/UiO-66-NH2-R surface (dissociative O2 chemisorption and the involvement of two oxygen species in benzene oxidation). According to the density functional theory simulation, the carbon and nitrogen impurities are to make the first XB step (i.e., hydrogen migration from the benzene molecule to the substrate) energetically favorable. The second hydrogen atom from the benzene molecule is also extracted effectively, while the oxygen derived from O2 facilitates further XB. The Pt0 sites dissociate the O2 and H2O molecules, while the product of the latter, i.e., free hydrogen and hydroxyl, makes the subsequent XB steps energetically favorable.

Thermocatalytic oxidation of a binary mixture of formaldehyde and toluene at ambient levels by a titanium dioxide supported platinum catalyst.

The thermocatalytic oxidative potential of various supported noble metal catalysts (SNMCs) is well-known for hazardous volatile organic compounds (VOCs), e.g., formaldehyde (FA) and toluene. However, little is known about SNMC performance against ambient VOC pollution with low concentration (subppm levels) relative to industrial effuluents with high concentrations (several hundred ppm). Here, the thermocatalytic oxidation performance of a titanium dioxide (TiO2)-supported platinum catalyst (Pt/TiO2) has been evaluated for a low-concentration binary mixture of FA and toluene at low temperatures and in the dark. A sample of TiO2 containing 1 wt% Pt with thermal reduction pre-treatment under hydrogen achieved 100 % conversion of FA (500 ppb) and toluene (100 ppb) at 130 °C and a gas hourly velocity of 59,701 h-1. Its catalytic activity was lowered by either a decrease in catalyst mass or an increase in VOC concentration, relative humidity, or flow rate. In situ diffuse reflectance infrared Fourier transform spectroscopy, density functional theory simulations, and molecular oxygen (O2) temperature-programmed desorption experiments were used to identify possible VOC oxidation pathways, reaction mechanisms, and associated surface phenomena. The present work is expected to offer insights into the utility of metal oxide-supported Pt catalysts for the low-temperature oxidative removal of gaseous VOCs in the dark, primarily for indoor air quality management.

The catalytic efficacy of modified manganese-cobalt oxides for room-temperature oxidation of formaldehyde in air.

Formaldehyde (FA) is a hazardous indoor air pollutant with carcinogenic propensity. Oxidation of FA in the dark at low temperature (DLT) is a promising strategy for its elimination from indoor air. In this light, binary manganese-cobalt oxide (0.1 to 5 mol L-1-MnCo2O4) is synthesized and modified in an alkaline medium (0.1-5 mol L-1 potassium hydroxide) for FA oxidation under room temperature (RT) conditions. Accordingly, 1-MnCo2O4 achieves 100 % FA conversion at RT (50 ppm and 7022 h-1 gas hourly space velocity (GHSV)). The catalytic activity of 1-MnCo2O4 is assessed further as a function of diverse variables (e.g., catalyst mass, relative humidity, FA concentration, molecular oxygen (O2) content, flow rate, and time on-stream). In situ diffuse reflectance infrared Fourier-transform spectroscopy confirms that FA molecules are adsorbed onto the active surface sites of 1-MnCo2O4 and oxidized into water (H2O) and carbon dioxide (CO2) through dioxymethylene (DOM) and formate (HCOO-) as the reaction intermediates. According to the density functional theory simulations, the higher catalytic activity of 1-MnCo2O4 can be attributed to the combined effects of its meritful surface properties (e.g., the firmer attachment of FA molecules, lower energy cost of FA adsorption, and lower desorption energy for CO2 and H2O). This work is the first report on the synthesis of alkali (KOH)-modified MnCo2O4 and its application toward the FA oxidative removal at RT in the dark. The results of this study are expected to provide valuable insights into the development of efficient and cost-effective non-noble metal catalysts against indoor FA at DLT.

The practical utility of ternary nickel-cobalt-manganese oxide-supported platinum catalysts for room-temperature oxidative removal of formaldehyde from the air.

Formaldehyde (FA), a carcinogenic oxygenated volatile organic compound, is present ubiquitously in indoor air. As such, it is generally regarded as a critical target for air quality management. The oxidative removal of FA under dark and room-temperature (RT) conditions is of practical significance. A series of ternary nickel-cobalt-manganese oxide-supported platinum catalysts (Pt/NiCoMnO4) have been synthesized for FA oxidative removal at RT in the dark. Their RT conversion values for 50 ppm FA (XFA) at 5,964 h-1 gas hourly space velocity (GHSV) decrease in the following order: 1 wt% Pt/NiCoMnO4 (100 %) > 0.5 wt% Pt/NiCoMnO4 (25 %) > 0.05 wt% Pt/NiCoMnO4 (14 %) > NiCoMnO4 (6 %). The catalytic performance of 1 wt% Pt/NiCoMnO4 has been examined further under the control of various process variables (e.g., catalyst mass, flow rate, relative humidity, FA concentration, time on stream, and molecular oxygen content). The catalytic oxidation of FA at low temperatures (e.g., RT and 60 °C) is accounted for by Langmuir-Hinshelwood mechanism (single-site competitive-adsorption), while Mars van Krevelen kinetics is prevalent at higher temperatures. In situ diffuse-reflectance infrared Fourier-transform spectroscopy reveals that FA oxidation proceeds through a series of reaction intermediates such as DOM, HCOO-, and CO32-. Based on the density functional theory simulations, the unique electronic structures of the nearest surface atoms (platinum and nickel) are suggested to be responsible for the superior catalytic activity of Pt/NiCoMnO4.

Low-temperature oxidative removal of benzene from the air using titanium carbide (MXene)-Supported platinum catalysts.

MXenes are an emerging class of two-dimensional (2D) inorganic materials with great potential for versatile applications such as adsorption and catalysis. Here, we describe the synthesis of a platinized titanium carbide MXene (Pt@Ti3C2) catalyst with varying amounts of platinum (0.1%-2 wt.%) for the low-temperature oxidation of benzene, an aromatic volatile organic compound often found in industrial flue gas. A 1% formulation of Pt@Ti3C2-R allowed near-complete (97%) oxidation of benzene to CO2 at 225 °C with a steady-state reaction rate (r) of 0.119 mol g-1·h-1. This low-temperature catalytic oxidation reaction was promoted by an increase in the lattice oxygen (O*)/Pt2+ species (active sites) of 1%Pt@Ti3C2-R from 45.3/34.6% to 71.0/61.1% through pre-thermal reduction under H2 flow, as revealed by X-ray photoelectron spectroscopy, temperature-programmed reduction, and in situ diffuse reflectance infrared Fourier transform spectroscopy analyses. The cataltyic activity of 1% Pt@Ti3C2-R against benzene was assessed under the control of the key process variables (e.g., catalyst mass, flow rate, benzene concentration, relative humidity, and time-on-stream) to help optimize the oxidation reaction process. The results provide new insights into the use of platinum-based 2D MXene catalysts for low-temperature oxidative removal of benzene from the air.

MLL4 binds TET3.

Human mixed lineage leukemia 4 (MLL4), also known as KMT2D, regulates cell type specific transcriptional programs through enhancer activation. Along with the catalytic methyltransferase domain, MLL4 contains seven less characterized plant homeodomain (PHD) fingers. Here, we report that the sixth PHD finger of MLL4 (MLL4PHD6) binds to the hydrophobic motif of ten-eleven translocation 3 (TET3), a dioxygenase that converts methylated cytosine into oxidized derivatives. The solution NMR structure of the TET3-MLL4PHD6 complex and binding assays show that, like histone H4 tail, TET3 occupies the hydrophobic site of MLL4PHD6, and that this interaction is conserved in the seventh PHD finger of homologous MLL3 (MLL3PHD7). Analysis of genomic localization of endogenous MLL4 and ectopically expressed TET3 in mouse embryonic stem cells reveals a high degree overlap on active enhancers and suggests a potential functional relationship of MLL4 and TET3.

ASXLs binding to the PHD2/3 fingers of MLL4 provides a mechanism for the recruitment of BAP1 to active enhancers.

The human methyltransferase and transcriptional coactivator MLL4 and its paralog MLL3 are frequently mutated in cancer. MLL4 and MLL3 monomethylate histone H3K4 and contain a set of uncharacterized PHD fingers. Here, we report a novel function of the PHD2 and PHD3 (PHD2/3) fingers of MLL4 and MLL3 that bind to ASXL2, a component of the Polycomb repressive H2AK119 deubiquitinase (PR-DUB) complex. The structure of MLL4 PHD2/3 in complex with the MLL-binding helix (MBH) of ASXL2 and mutational analyses reveal the molecular mechanism which is conserved in homologous ASXL1 and ASXL3. The native interaction of the Trithorax MLL3/4 complexes with the PR-DUB complex in vivo depends solely on MBH of ASXL1/2, coupling the two histone modifying activities. ChIP-seq analysis in embryonic stem cells demonstrates that MBH of ASXL1/2 is required for the deubiquitinase BAP1 recruitment to MLL4-bound active enhancers. Our findings suggest an ASXL1/2-dependent functional link between the MLL3/4 and PR-DUB complexes.

Drug targets for lymphatic filariasis: a bioinformatics approach.

This review article discusses the current scenario of the national and international burden due to lymphatic filariasis (LF) and describes the active elimination programmes for LF and their achievements to eradicate this most debilitating disease from the earth. Since, bioinformatics is a rapidly growing field of biological study, and it has an increasingly significant role in various fields of biology. We have reviewed its leading involvement in the filarial research using different approaches of bioinformatics and have summarized available existing drugs and their targets to re-examine and to keep away from the resisting conditions. Moreover, some of the novel drug targets have been assembled for further study to design fresh and better pharmacological therapeutics. Various bioinformatics-based web resources, and databases have been discussed, which may enrich the filarial research.

Gas-phase hydrogenation of furfural into value-added chemicals: The critical role of metal-based catalysts.

Furfural (FF: aldehyde derivable from lignocellulosic biomass) has been widely recognized as a versatile building block for eco-friendly and sustainable applications to reduce industrial reliance on fossil-fuel carbon sources. Hydrogenation of FF, in particular, is recognized as one of the most effective routes for producing various value-added chemicals (e.g., furfuryl alcohol and 2-methylfuran). The gas-phase FF hydrogenation reaction offers economic and environmental advantages over its liquid-phase counterpart in conversion efficiency, product selectivity, and kinetics. The operation of the former does not require high hydrogen pressures or hazardous solvents while not generating undesirable by-products (due to reduced selectivity toward the ring-opening reaction). In this context, the utility of noble and non-noble metal catalyst systems has been recognized for their potential to induce effective FF hydrogenation in the gas phase. The present review addresses current understandings and recent developments in research on gas-phase FF hydrogenation and the factors governing the performance of metal-based catalysts (e.g., materials and surface chemistry; conversion efficiency; product selectivity; and the mechanisms, pathways, and kinetics of the associated reactions). Current shortcomings and research avenues are also discussed to help establish a roadmap for future development of the gas-phase FF hydrogenation technology and associated disciplines. Overall, the present review is expected to offer much-needed insights into the scalability of metal-based catalytic systems for efficient FF hydrogenation in the gas phase.

Biosensor-integrated transposon mutagenesis reveals rv0158 as a coordinator of redox homeostasis in Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) is evolutionarily equipped to resist exogenous reactive oxygen species (ROS) but shows vulnerability to an increase in endogenous ROS (eROS). Since eROS is an unavoidable consequence of aerobic metabolism, understanding how Mtb manages eROS levels is essential yet needs to be characterized. By combining the Mrx1-roGFP2 redox biosensor with transposon mutagenesis, we identified 368 genes (redoxosome) responsible for maintaining homeostatic levels of eROS in Mtb. Integrating redoxosome with a global network of transcriptional regulators revealed a hypothetical protein (Rv0158) as a critical node managing eROS in Mtb. Disruption of rv0158 (rv0158 KO) impaired growth, redox balance, respiration, and metabolism of Mtb on glucose but not on fatty acids. Importantly, rv0158 KO exhibited enhanced growth on propionate, and the Rv0158 protein directly binds to methylmalonyl-CoA, a key intermediate in propionate catabolism. Metabolite profiling, ChIP-Seq, and gene-expression analyses indicate that Rv0158 manages metabolic neutralization of propionate toxicity by regulating the methylcitrate cycle. Disruption of rv0158 enhanced the sensitivity of Mtb to oxidative stress, nitric oxide, and anti-TB drugs. Lastly, rv0158 KO showed poor survival in macrophages and persistence defect in mice. Our results suggest that Rv0158 is a metabolic integrator for carbon metabolism and redox balance in Mtb.