Ammonia induces a phase transformation of perovskite (CH sub(3)NH sub(3))PbI sub(3), leading to a rapid (<1 s) change in its color from brown to colorless (400-800 nm). This color change is reversed ...within seconds upon removing the NH sub(3) source.
Glutamine synthetase, encoded by the gene GLUL, is an enzyme that converts glutamate and ammonia to glutamine. It is expressed by endothelial cells, but surprisingly shows negligible ...glutamine-synthesizing activity in these cells at physiological glutamine levels. Here we show in mice that genetic deletion of Glul in endothelial cells impairs vessel sprouting during vascular development, whereas pharmacological blockade of glutamine synthetase suppresses angiogenesis in ocular and inflammatory skin disease while only minimally affecting healthy adult quiescent endothelial cells. This relies on the inhibition of endothelial cell migration but not proliferation. Mechanistically we show that in human umbilical vein endothelial cells GLUL knockdown reduces membrane localization and activation of the GTPase RHOJ while activating other Rho GTPases and Rho kinase, thereby inducing actin stress fibres and impeding endothelial cell motility. Inhibition of Rho kinase rescues the defect in endothelial cell migration that is induced by GLUL knockdown. Notably, glutamine synthetase palmitoylates itself and interacts with RHOJ to sustain RHOJ palmitoylation, membrane localization and activation. These findings reveal that, in addition to the known formation of glutamine, the enzyme glutamine synthetase shows unknown activity in endothelial cell migration during pathological angiogenesis through RHOJ palmitoylation.
•Ammonia escape mass transfer is presented.•Current state of developments in ammonia escape abatement technologies are reviewed.•Research gaps in ammonia escape abatement technologies are ...developed.•Challenges and future prospects of ammonia escape abatement are suggested.
CO2 capture using ammonia solvent is an alternative to the conventional amine-based CO2 capture technology. While ammonia escape is one of the main barrier limiting its implementation. The present work reviews the current status of ammonia escape mechanisms and its inhibition technologies. The chemistry of ammonia-based absorption and desorption are analyzed, and the mass transfer of the ammonia escape are presented and discussed. Most suppression approaches for ammonia slip are in lab- and bench-scale studies. The representative development of the pilot-scale tests involves NH3 abatement and recycling process and chilled ammonia process (CAP). Some other novel processes have been reported the potential to reduce ammonia slip significantly and relatively lower energy penalty, but some technical issues including the process modification and parameters optimization should be resolved to secure economic feasibility. Integration of different ammonia inhibition approaches is suggested for the future development of ammonia slip suppression process.
A number of class I lyase‐like enzymes, including aromatic ammonia‐lyases and aromatic 2,3‐aminomutases, contain the electrophilic 3,5‐dihydro‐5‐methylidene‐4H‐imidazol‐4‐one (MIO) catalytic moiety. ...This study reveals that Pseudomonas fluorescens R124 strain isolated from a nutrient‐limited cave encodes a histidine ammonia‐lyase, a tyrosine/phenylalanine/histidine ammonia‐lyase (XAL), and a phenylalanine 2,3‐aminomutase (PAM), and demonstrates that an organism under nitrogen‐limited conditions can develop novel nitrogen fixation and transformation pathways to enrich the possibility of nitrogen metabolism by gaining a PAM through horizontal gene transfer. The novel MIO enzymes are potential biocatalysts in the synthesis of enantiopure unnatural amino acids. The broad substrate acceptance and high thermal stability of PfXAL indicate that this enzyme is highly suitable for biocatalysis.
The first MIO trio: The P. fluorescens R124 strain encodes a histidine ammonia‐lyase (HAL), a tyrosine/phenylalanine/histidine ammonia‐lyase (XAL), and a phenylalanine 2,3‐aminomutase (PAM) to demonstrate that an organism under metabolic stress can utilize more than two different 3,5‐dihydro‐5‐methylidene‐4H‐imidazol‐4‐one (MIO) enzymes, which are highly suitable biocatalysts for the production of enantiopure aromatic amino acids.
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•NH3 fermentation was conducted in a continuous mode at increasing organic N input.•Highest value ever reported: concentration of 12 g TAN-N/L with 36 g NH3-N/L/d.•Increased N loading ...shifted AF rate-limiting step from hydrolysis to deamination.•Microbial adaptation by stepwise increasing NH3 surroundings enhances tolerance.•Reduction in the energy consumption to 1/3 for NH3 extraction (12.0 vs. 3.8 g N/L).
Being considered as a valuable resource and energy carrier, extensive research is going on to efficiently extract ammonia (NH3) from anaerobic digestate. However, due to the well-known NH3 inhibition on methanogens, the total NH3 nitrogen (TAN) concentration is typically limited to 1–4 g N/L in digestate, making the NH3 extraction process energy-consumptive. Here, NH3 fermentation, specifically targeting augmented NH3 production through biological reaction, was performed in a continuous mode. With the increase of gelatin input (10 to 150 g COD/L), NH3 concentration and volumetric productivity gradually increased, reaching 12.0 g TAN-N/L and 36.0 g NH3-N/L/d, which were the highest values ever reported. The stepwise increase in NH3 exposure prompted a shift in microbial dominance towards Hathewaya (from 1 % to 68 %), a critical factor for having high NH3 tolerance. Finally, NH3 stripping results suggested that highly concentrated broth could reduce the specific energy consumption for NH3 extraction to 1/3.
Brown planthopper (BPH) is one of the most destructive insects affecting rice (Oryza sativa L.) production. Phenylalanine ammonialyase (PAL) is a key enzyme involved in plant defense against ...pathogens, but the role of PAL in insect resistance is still poorly understood. Here we show that expression of the majority of PALs in rice is significantly induced by BPH feeding. Knockdown of OsPALs significantly reduces BPH resistance, whereas overexpression of OsPAL8 in a susceptible rice cultivar significantly enhances its BPH resistance. We found that OsPALs mediate resistance to BPH by regulating the biosynthesis and accumulation of salicylic acid and lignin. Furthermore, we show that expression of OsPAL6 and OsPAL8 in response to BPH attack is directly up-regulated by OsMYB30, an R2R3 MYB transcription factor. Taken together, our results demonstrate that the phenylpropanoid pathway plays an important role in BPH resistance response, and provide valuable targets for genetic improvement of BPH resistance in rice.
Characterization of the aromatic ammonia–lyase from Loktanella atrilutea (LaAAL) revealed reduced activity towards canonical AAL substrates: l‐Phe, l‐Tyr, and l‐His, contrasted by its pronounced ...efficiency towards 3,4‐dimethoxy‐l‐phenylalanine. Assessing the optimal conditions, LaAAL exhibited maximal activity at pH 9.5 in the ammonia elimination reaction route, distinct from the typical pH ranges of most PALs and TALs. Within the exploration of the ammonia source for the opposite, synthetically valuable ammonia addition reaction, the stability of LaAAL exhibited a positive correlation with the ammonia concentration, with the highest stability in 4 M ammonium carbamate of unadjusted pH of ~9.5. While the enzyme activity increased with rising temperatures yet, the highest operational stability and highest stationary conversions of LaAAL were observed at 30 °C. The substrate scope analysis highlighted the catalytic adaptability of LaAAL in the hydroamination of diverse cinnamic acids, especially of meta‐substituted and di‐/multi–substituted analogues, with structural modelling exposing steric clashes between the substrates’ ortho–substituents and catalytic site residues. LaAAL showed a predilection for ammonia elimination, while classifying as a tyrosine ammonia–lyase (TAL) among the natural AAL classes. However, its distinctive attributes, such as genomic context, unique substrate specificity and catalytic fingerprint, suggest a potential natural role beyond those of known AAL classes.
The aromatic ammonia–lyase from Loktanella atrilutea (LaAAL) displays a high activity towards 3,4‐dimethoxy trans–cinnamic acid, with a surprisingly diminished activity towards natural AAL substrates. Under the optimal reaction conditions LaAAL exhibited versatility for the transformation of various cinnamic acids. While LaAAL might be classified as a tyrosine ammonia‐lyase (TAL, E.C. 4.3.1.23), its strongly distinctive attributes argue for an elemental role in the transformation of non‐natural phenylalanines.
Poly(ADP-ribose)polymerase-1 (PARP-1) is an important target for drug design for several therapeutic applications. 5-Aminoisoquinolin-1-one (5-AIQ) is a highly water-soluble lead compound; synthetic ...routes to 3-substituted analogues were explored. Tandem Hurtley coupling of I2-diketones with 2-bromo-3-nitrobenzoic acid, retro-Claisen acyl cleavage and cyclisation gave the corresponding 3-substituted 5-nitroisocoumarins. Treatment with ammonia at high temperature and reduction with tin(II) chloride gave eleven target 3-substituted 5-AIQs, which were all soluble in water (>1% w/v) as their HCl salts. Most were more potent than 5-AIQ as inhibitors of PARP-1 and of PARP-2 in vitro, the most active being 5-amino-3-methylisoquinolin-1-one (PARP-1: IC50 = 0.23 mu M vs IC50 = 1.6 mu M for 5-AIQ). Some rationalisation of the SAR was achieved through molecular modelling.
Ammonia can be a hydrogen source for many applications including fuel cells. Using Ru or CsaRu as the catalyst, hydrogen is generated from ammonia by decomposition reaction. These catalysts are ...deposited on carbon powder by either chemical reduction or precipitation method in this study. Different carbon powder pre-treatment solutions and catalyst deposition conditions are evaluated. Nitric acid pre-treatment followed by precipitation at pH of 6 produces the highest catalyst loading from solution with given concentration of catalyst precursor. Hydrogen generation rate is measured at different catalyst compositions, ammonia inlet flow rates, decomposition temperatures, amount of catalyst packing, and ratio of Cs/Ru. The optimal condition for the ammonia decomposition reaction is Cs/Ru weight ratio at 3, ammonia inlet flow at 6ANBmlANBmin-1, reaction temperature at 400ANB degree C. At this condition, the ammonia conversion rate reaches 90% and hydrogen generation rate reaches 29.8ANBmmol/min-gcat.
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