Aspartate Research Articles

A novel Au-NPs/DBTTA nanocomposite-based electrochemical sensor for the detection of ascorbic acid (AA)

Purpose Ascorbic acid, a water-soluble antioxidant, is an essential component of the human diet and is known for its potent antioxidant properties against several diseases. In recent years, there has been increasing interest in the development of nonenzymatic sensors due to their simplicity, efficiency and excellent selectivity. The aim of this study is to present a selective and sensitive method for the detection of ascorbic acid in aqueous system using a new electrochemical non-enzymatic sensor based on a gold nanoparticles Au-NPs-1,3-di(4-bromophényl)-5-tert-butyl-1,3,5-triazinane (DBTTA) composite. Design/methodology/approach Using the square wave voltammetry (SWV) technique, a series of Au-NPs-DBTTA composites were successfully developed and investigated. First, DBTTA was synthesized via the condensation of tert-butylamine and a4-bromoaniline. The structure obtained was identified by IR, 1H NMR and 13C NMR analysis. A glassy carbon electrode (GCE) was modified with 10–1 M DBTTA dissolved in an aqueous solution by cyclic voltammetry in the potential range of 1–1.4 V. Au-NPs were then deposited on the DBTTA/GCE by a chronoamperometric technique. SWV was used to study the electrochemical behavior of the modified electrode (DBTTA/Au-NPs/GCEs). To observe the effect of nanoparticles, ascorbic acid in a buffer solution was analyzed by SWV at the modified electrode with and without gold nanoparticles (Au-NPs). Findings The DBTTA/Au-NPs/GCE showed better electroanalytical results. The detection limit of 10–5 M was obtained and the electrode was proportional to the logarithm of the AA concentration in the range of 5 × 10−3 M to 1 × 10−1 with very good correlation parameters. Originality/value It was also found that the elaborated sensor exhibited reproducibility and excellent selectivity against interfering molecules such as uric acid, aspartic acid and glucose. The proposed sensor was tested for the recognition of AA in orange, and satisfactory results were obtained.

Glycated walnut meal peptide‑calcium chelates (COS-MMGGED-Ca): Preparation, characterization, and calcium absorption-promoting

This study isolated a novel peptide MMGGED with strong calcium-binding capacity from defatted walnut meal and synthesized a novel peptide‑calcium chelate COS-MMGGED-Ca with high stability via glycation. Structural characterization and computer simulation identified binding sites, while in vitro digestion stability and calcium transport experiments explored the chelate's properties. Results showed that after glycation, COS-MMGGED bound Ca2+ with 88.75 ± 1.75 %, mainly via aspartic and glutamic acids. COS-MMGGED-Ca released Ca2+ steadily (60.27 %), with thermal denaturation temperature increased by 18 °C and 37 °C compared to MMGGED-Ca, indicating good processing performance. Furthermore, COS-MMGGED significantly enhanced Ca2+ transport across Caco-2 monolayers, 1.13-fold and 1.62-fold higher than CaCl2 and MMGGED, respectively, at 240 h. These findings prove glycation enhances structural properties, stability, calcium loading, and transport of peptide‑calcium chelates, providing a scientific basis for developing novel efficient calcium supplements and high-value utilization of walnut meal.

Optimization and Detection of Freshness Biomarkers of Atlantic Salmon Subjected to Different Vacuum Packaging Conditions during Storage at 0 °C by Metabolomics and Molecular Docking.

The freshness of Atlantic salmon is influenced mainly by tissue metabolism, which in turn is affected by storage time and conditions. The alterations in taste profiles and nutritional values of salmon when packaged using vacuum methods have not been fully understood, and the factors contributing to these changes require further research. In this work, the extraction method for flavor nutrients from salmon was optimized via the Plackett-Burman (PB) test. A sensitive and rapid targeted metabolomics method for the simultaneous determination of 34 nutrients was successfully established via ultra-performance liquid chromatography-triple quadrupole/linear ion trap composite mass spectrometry (UHPLC-QTRAP/MS), and various nutritional compositions during storage at 0 °C under different vacuum conditions (0 kPa or -90 kPa) for 4 and 8 days were analyzed. Results showed that storage time had a significant effect on salmon metabolism. The total amino acids decreased by 62.95% and 65.89% at 0 kPa and -90 kPa, respectively. Notably, a marked reduction in histidine after 8 days at -90 kPa may have diminished bitterness, while decreased levels of umami-tasting amino acids like glutamine and aspartic acid affected the overall flavor profile. Overall, the packaging conditions at 0 °C and 0 kPa were more suitable for the preservation of most nutrients in salmon. Pathway enrichment analysis revealed that the reduction in substances was mainly related to the alanine, aspartate, and glutamate metabolism pathways. Alanine, inosine, and histidine, whose levels changed significantly, can bind to the typical umami taste receptor TIR1/TIR3 and can be biomarkers to monitor and determine the freshness or spoilage of salmon after 4-8 days of storage. This study revealed the changes in small-molecule nutrients in salmon during storage under different packaging conditions, which provides a reference for the packaging preservation technology of fresh salmon and new ideas for the evaluation of salmon quality and determination of freshness.

Characterization of mechanical behavior and cementing mechanism of high-strength composites using biomimetic chemically induced calcium carbonate precipitation method

Biomimetic mineralized mortar (BMM) represents a novel green cementitious material, increasingly recognized for its environmental sustainability. In this study, four typical amino acids including acidic amino acids (aspartic acid, glutamic acid), neutral amino acid (threonine), and basic amino acid (arginine), are employed as crystal modifiers to develop the high-strength BMM (HBMM) based on the biomimetic chemically induced calcium carbonate precipitation (BCICP) method. The mechanical properties and failure morphology of HBMM were evaluated through unconfined compressive strength (UCS) test. The microstructure characteristics of HBMM were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and contact angle test. The results show that amino acid-modified calcium carbonate precipitation can effectively cement loose sand particles and significantly improve the strength of the HBMM. The failure modes of HBMM observed include local failure, vertical splitting failure, shear failure, and splitting-shear mixed failure. Notably, aspartic acid and glutamic acid can induce the formation of vaterite-phase calcium carbonate crystals, while threonine and arginine facilitate the formation of aragonite-phase calcium carbonate crystals. The hydrogen bonding between modified calcium carbonate crystals and silanol groups on the silica surface ensures a tight adhesion of the precipitate to sand surfaces, filling gaps and cementing particles. This study elucidates that using amino acids as modifiers in the BCICP method can significantly enhance the strength of HBMM and influence its microstructure, offering valuable insights for its potential practical applications.

Asparagine synthetase regulates the proliferation and differentiation of chicken skeletal muscle satellite cells.

Asparagine synthetase (ASNS) is an aminotransferase responsible for the biosynthesis of aspartate by using aspartic acid and glutamine. ASNS is highly expressed in fast-growing broilers, but few studies have reported the regulatory role of ASNS in muscle development. To explore the function of ASNS in chicken muscle development, the expression of ASNS in different chicken breeds and tissues were first performed by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). Then, using real-time quantitative RT-PCR, western blot, EdU assay, cell cycle assay and immunofluorescence, the effects of ASNS on the proliferation and differentiation of chicken skeletal muscle satellite cell (SMSC) were investigated. Finally, potential mechanisms by which ASNS influences chicken muscle fiber differentiation were identified through RNA-Seq. The mRNA expression pattern of ASNS in muscles mirrors trends in muscle fiber cross-sectional area, average daily weight gain, and muscle weight across different breeds. ASNS knockdown inhibited SMSC proliferation, while overexpression showed the opposite. Moreover, ASNS attenuated SMSC differentiation by activating the Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) pathway. Additionally, 5-aminoimidazole-4-carboxamide1-β-D-ribofuranoside (AICAR) treatment suppressed the cell differentiation induced by siRNA-ASNS. RNA-Seq identified 1968 differentially expressed genes (DEGs) during chicken SMSC differentiation when overexpression ASNS. Gene Ontology (GO) enrichment analysis revealed that these DEGs primarily participated in 8 biological processes, 8 cellular components, and 4 molecular functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified several significantly enriched signaling pathways, such as the JAK-STAT signaling pathway, TNF signaling pathway, Toll-like receptor signaling pathway, and PI3K-Akt signaling pathway. ASNS promotes proliferation while inhibits the differentiation of chicken skeletal muscle satellite cells. This study provides a theoretical basis for studying the role of ASNS in muscle development.

Constructing an artificial in vitro multi-enzyme cascade pathway to convert glycerol and CO2 into L-aspartic acid

Developing utilization technologies for biomass resources, exploring their applications in the fields of energy and chemical engineering, holds significant importance for promoting sustainable development and constructing a green, low-carbon society. In this study, we designed a non-natural in vitro multi-enzyme system for converting glycerol and CO2 into L-aspartic acid (L-Asp). The coupled system utilized eight enzymes, including alditol oxidase (ALDO), catalase-peroxidase (CAT), lactaldehyde dehydrogenase (ALDH), glycerate 2-kinase (GK), phosphopyruvate hydratase (PPH), phosphoenolpyruvate carboxylase (PPC), L-aspartate dehydrogenase (ASPD), and polyphosphate kinase (PPK), to convert the raw materials into L-Asp in one-pot coupled with NADH and ATP regeneration. Under optimal reaction conditions, 18.6 mM of L-Asp could be produced within 2.0 h at a total enzyme addition of 4.85 mg/mL, demonstrating the high efficiency and productivity characteristics of the designed system. Our technological application provides new insights and methods for the development of biomass resource utilization technologies.

Untargeted metabolomics combined with chemometrics reveals distinct metabolic profiles across two sparkling cider fermentation stages

This study aimed to examine the metabolic profiles of Saccharomyces cerevisiae yeasts (WLS21 and Y41) in two phases of sparkling cider making (normal and pressure fermentation) by combining untargeted metabolomic with chemometrics. The results showed that of the 634 nonvolatile metabolites identified using LC-MS and 83 volatile metabolites identified by GC–MS, the differential metabolites were 226 and 54, respectively. Metabolic pathway and correlation analyses showed that aspartic acid, phenylalanine and tyrosine, glutamic acid and purine metabolism were associated with flavor formation. The pressure fermentation process increased apigenin, naringenin, toxifolin, pyridoxine and thiamine contents in the final cider. These findings provide useful information and new research ideas for the formation of flavor in sparkling cider and the regulation of phenolic and vitamin production by microbial stress fermentation.

Dry deposition fluxes, source, and potential ecological impact of amino acids in the Danjiangkou Reservoir of China's South-to-North water transfer project

As a nitrogen source for biological growth, amino compounds can participate in global nitrogen cycle processes and directly impact ecosystems. Dry deposition samples were collected from September 2020 to August 2021 from the Danjiangkou Reservoir of the South-to-North Water Transfer Project. The dry deposition characteristics of amino acids in the reservoir area were analyzed, their sources were resolved, and the potential ecological impacts were evaluated. The results showed that the dry deposition flux of dissolved free amino acids was 0.48 kg N ha−1 yr−1 and that of dissolved combined amino acids was 1.09 kg N ha−1 yr−1 in Danjiangkou Reservoir. The dominant amino acid fractions were glutamic acid and aspartic acid. Agricultural activities, coal combustion, and primary biogenic particles influenced the amino acid deposition in the reservoir area. The potential source areas for amino acid deposition mainly influenced the northeast, southwest, northwest, and south of the reservoir. The amounts of amino acids entering the water bodies via dry deposition was 85.72 t N yr−1, contributing 0.83 g C m−2 yr−1 of new production to the reservoir water bodies. To summarize, this research depicted that the potential ecological impact of dry deposition of amino acids on artificial freshwater lakes should not be overlooked.

Production of Single Cell Protein (SCP) from the Peel Waste of Pea, Potato, and Banana by Aspergillus Flavus NRRL 21882 as an Efficient Organic Poultry Supplement.

Food protein deficit has become a major issue worldwide, particularly in underdeveloped countries. Scientists are searching for a variety of less expensive solutions to this issue. One of these less expensive methods is to create single cell protein as a substrate from leftover fruit and vegetable waste, which is typically thrown away. In this regard, the fungal strain Aspergillus flavus (NRRL 21882) was used for the synthesis of SCP (single cell protein) from the waste of banana, potato, and pea. In this manner, 30 samples were collected from the whole substrate with a share of 10 samples each from banana, potato, and pea peels, which were in turn dried and powdered finely. The fermentation process was done by the process of solid state fermentation. Aspergillus flavus (NRRL 21882) generated the highest percentage, i.e. 60.67%, of crude protein from the pea peels. The composition of amino acids in crude proteins was also investigated. The findings demonstrated that the highest percentage of aspartic acid (13.34 ± 0.80%) and glutamic acid (14.92 ± 0.69%) was found in A. flavus single cell protein produced from pea peels. Soybean was supplemented with single cell protein in the boilers' diet. Compared to all treated groups, there was a substantial (p ≤ 0.05) increase in the level of antibody titer against the Newcastle disease vaccine. The supplementation of single cell protein with soybean meal had no effect on the levels of liver enzymes. The liver enzymes found in all four groups (A, B, C, and D) were within normal limits. None of the examined groups experienced any change in the feed conversion ratio, with all groups exhibiting an average FCR of 1.6. The current study concludes that broiler health and immunity is increased by supplementing poultry feed with single cell protein.

A new enzymatic clarification method for pomegranate juice: Removal of defects and improvement of quality by tannase, lactonase and papain

Effects of clarification with “tannase,” “tannase+lactonase,” “papain,” “aspartic protease” and “tannase+lactonase+papain” on defects (turbidity, sediment and color loss) and important constituents (phenolics, anthocyanins, proteins and amino acids) of pomegranate juice (PJ) were investigated. Lactonase [human-derived (H-PON-1 and H-PON-2) and rabbit-derived (R-PON-1, R-PON-2 and R-PON-3)] was used during juice clarification for the first time. Phenolics and amino acids were quantified by HPLC-DAD-MS and HPLC. After clarifications with “tannase (1 g/L)+R-PON-1 (0.33 mg/L)” and “tannase (1 g/L)+R-PON-1 (0.33 mg/L)+papain (10 mg/L)” at 30℃ for 90 min, sediment was completely eliminated during storage at 20℃ for a month. Among these treatments, “tannase+R-PON-1” provided the lowest turbidity formation rate. The most effective parameter to prevent sediment was the ratio of “prolamin to trigalloyl-HHDP-glucose-isomer-2” that should be ≥205.4 (r=–1.000). Moreover, “tannase+R-PON-1” caused 4.3 times lower turbidity than control group after storage. To retain low turbidity (≤10 NTU) during storage, galloyl-glucose-isomer and HHDP-galloyl-hexoside-3 should completely be removed from PJ and, punigluconin and trigalloyl-HHDP-glucose-isomer-2 contents should be ≤0.19 and ≤0.04 mg/L, respectively. Furthermore, “tannase+R-PON-1” provided a significant contribution to anthocyanin copigmentation. The most effective copigments in PJ were HHDP-galloyl-glucuronide, punigluconin, punicalagin-2, punicalagin-3, aspartic acid, glutamic acid and alanine. “Tannase+R-PON-1” is recommended to produce a high-quality PJ.

Stereoregular polyamides with optically‐pure aspartame‐type diketopiperazine derivatives

AbstractPolyamides (PAs) with aspartame‐derived diketopiperazine (DKP) form specific particles and exhibit high heat resistance. In this study, we investigated the stereostructures of aspartic acid and phenylalanine, which constitute aspartame DKP. Diketopiperazines with different stereostructures were synthesized from D‐ and L‐aspartic acid and D‐ and L‐phenylalanine, and LL‐, DD‐, and LD‐type aminodiketopiperazines (LL, DD, and LD‐ADKPs) were obtained. These ADKPs differed in their crystal forms depending on their stereoisomeric structures. Furthermore, PAs were formed from these ADKPs via polycondensation using triphenyl phosphite/pyridine, and their heat resistance was approximately 300 °C. The secondary structure of each PA was evaluated by circular dichroism, which suggested that LD‐type PAs had a mixed secondary structure of coils and helical structures, unlike the LL and DD types. Precipitated LL, DD, and LLcoDD PAs formed similar particles, whereas the particles of the large LD‐type PA had different particle shapes owing to their different conformations.

Multilevel metabolic engineering for enhanced synthesis of S-adenosylmethionine by Bacillus amyloliquefaciens.

To enhance the de novo synthesis of SAM, the effects of several key genes on SAM synthesis were examined based on modular strategy, and the key genes were manipulated to obtain an engineered strain with high SAM production. In Bacillus amyloliquefaciens HSAM6, the deletion of argG gene to block aspartic acid branching degradation increased SAM titer to 254.78 ± 15.91 mg/L, up 18% from HSAM6. Subsequently, deleting the moaA gene to boost the supply of 5-methyltetrahydrofolate led to the stunted growth and the plummeting yield of SAM. Further improvement of strain growth by overexpression of the citA gene, while SAM synthesis was not significantly enhanced. Finally, the maximum SAM titer (452.89 ± 13.42mg/L) was obtained by overexpression SAM2 gene using the multicopy plasmid. The deletion of argG gene and the overexpression of SAM2 gene significantly improved SAM synthesis in B. amyloliquefaciens.

Systematic mutational analysis reveals an essential role of N275 in IgE stability.

Therapeutic antibodies have predominantly been IgG-based. However, the ongoing clinical trial of MOv18 IgE has highlighted the potential of using IgE antibodies in cancer therapy. While extensive studies targeting IgG glycosylation resulted in a rational basis for the development of enhanced biotherapeutics, IgE glycosylation remains an area with limited analyses. Previous studies on the role of IgE glycosylation present conflicting data with one study emphasizing the importance of N275 and T277 residues for FcεRI binding whereas another asserts the nonsignificance of IgE glycosylation in receptor interaction. While existing literature underscores the significance of glycans at the N275 position for binding to FcεR1 receptor and initiation of anaphylaxis, the role of other IgE glycosylation sites in folding or receptor binding remains elusive. This study systematically investigates the functional significance of N-linked glycosylation sites in the heavy chain of IgE which validates the pivotal role of N275 residue in IgE secretion and stability. Replacement of this asparagine to non-amine group moieties does not affect IgE function in vitro, yet substitution with aspartic acid compromises antibody yield. The deglycosylated IgE variant exhibits superior efficacy, challenging the conventional importance of glycosylation for effector function. In summary, our study unveils an intricate relationship between N-glycosylation sites and the structural-functional dynamics of IgE antibodies. Furthermore, it offers novel insights into the IgE scaffold, paving the way for the development of more effective and stable IgE-based therapeutics.

Hydrolysates from cauliflower and artichoke industrial wastes as biostimulants on seed germination and seedling growth: a chemical and biological characterization.

Cauliflower (Brassica oleracea L.) and globe artichoke (Cynara scolymus L.) are vegetables with a high waste index mainly related to stems and leaves. In this study, enzymatic hydrolysates obtained from these wastes were proposed to be used as plant biostimulants. Life cycle assessment methodology was also applied to evaluate environmental performances related to cauliflower and artichoke byproducts. Hydrolysates (HYs) were chemically and biologically characterized. Amino acids, organic acids, amines, polyols, mineral elements, phenols, tannins, flavonoids and sulfur compounds were identified and quantified by means of NMR, inductively coupled plasma mass spectrometry and UV-visible analyses. Cauliflower leaf and flower HYs showed the highest concentration of free amino acids, whereas stems showed the highest concentration of Ca. Regarding artichoke, asparagine, glutamine and aspartic acid were exclusively detected in stems, whereas artichoke leaves showed the highest Mg and Mn levels together with the highest antioxidant activity. The HYs diluted in water were tested as biostimulants. The impacts of five concentrations of HYs (0.00, 0.28, 0.84, 2.52 and 7.56 g L-1) on seed germination and early seedling growth of crimson clover, alfalfa, durum wheat and corn were investigated. The application of artichoke biostimulant (0.28 g L-1) positively influenced the coefficient of velocity of germination in alfalfa, crimson clover and durum wheat, whereas cauliflower biostimulant significantly improved corn germination speed. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Structural Reorganization Mechanism of the Aβ42 Fibril Mediated by N-Substituted Oligopyrrolamide ADH-353.

The inhibition of amyloid-β (Aβ) fibrillation and clearance of Aβ aggregates have emerged as a potential pharmacological strategy to alleviate Aβ aggregate-induced neurotoxicity in Alzheimer's disease (AD). Maity et al. shortlisted ADH-353 from a small library of positively charged N-substituted oligopyrrolamides for its notable ability to inhibit Aβ fibrillation, disintegrate intracellular cytotoxic Aβ oligomers, and alleviate Aβ-induced cytotoxicity in the SH-SY5Y and N2a cells. However, the molecular mechanism through which ADH-353 interacts with the Aβ42 fibrils, leading to their disruption and subsequent clearance, remains unclear. Thus, a detailed molecular mechanism underlying the disruption of neurotoxic Aβ42 fibrils (PDB ID 2NAO) by ADH-353 has been illuminated in this work using molecular dynamics simulations. Interestingly, conformational snapshots during simulation depicted the shortening and disappearance of β-strands and the emergence of a helix conformation, indicating a loss of the well-organized β-sheet-rich structure of the disease-relevant Aβ42 fibril on the incorporation of ADH-353. ADH-353 binds strongly to the Aβ42 fibril (ΔGbinding= -142.91 ± 1.61 kcal/mol) with a notable contribution from the electrostatic interactions between positively charged N-propylamine side chains of ADH-353 with the glutamic (Glu3, Glu11, and Glu22) and aspartic (Asp7 and Asp23) acid residues of the Aβ42 fibril. This aligns well with heteronuclear single quantum coherence NMR studies, which depict that the binding of ADH-353 with the Aβ peptide is driven by electrostatic and hydrophobic contacts. Furthermore, a noteworthy decrease in the binding affinity of Aβ42 fibril chains on the incorporation of ADH-353 indicates the weakening of interchain interactions leading to the disruption of the double-horseshoe conformation of the Aβ42 fibril. The illumination of key interactions responsible for the destabilization of the Aβ42 fibril by ADH-353 in this work will greatly aid in designing new chemical scaffolds with enhanced efficacy for the clearance of Aβ aggregates in AD.

Amino acid surface modified bioglass: A candidate biomaterial for bone tissue engineering1.

Bioglasses are solid materials consisted of sodium oxide, calcium oxide, silicon dioxide and phosphorus in various proportions and have used in bone tissue engineering. There have been ongoing efforts to improve the surface properties of bioglasses to increase biocompatibility and performance. The aim of the present study is to modify the bioglass surface with an amino acid mixture consisting of arginine, aspartic acid, phenylalanine, cysteine, histidine and lysine, to characterize the surface, and to evaluate the performance and biocompatibility in vitro and in vivo. The untreated bioglass, bioglass kept in simulated body fluid (SBF), and modified bioglass were used in further evaluation. After confirmation of the surface modification with FT-IR analyses and SEM analyses, MC3T3-E1 preosteoblasts adhesion on the surface was also revealed by SEM. The modified bioglass had significantly higher ALP activity in colorimetric measurement, rate of calcium accumulations in Alizarin red s staining, lower rate of cell death in Annexin-V/PI staining to determine apoptosis and necrosis. Having higher cell viability rate in MTT test and absence of genotoxicity in micronucleus test (OECD 487), the modified bioglass was further confirmed for biocompatibility in vitro. The results of the rat tibial defect model revealed that the all bioglass treatments had a significantly better bone healing score compared to the untreated negative control. However, the modified bioglass exhibited significantly better bone healing efforts especially during the first and the second months compared to the other bioglass treatment treatments. As a result, the amino acid surface modification of bioglasses improves the surface biocompatibility and osteogenic performance that makes the amino acid modified bioglass a better candidate for bone tissue engineering. RESEARCH HIGHLIGHTS: Bioglass surface modification with amino acids contributes to bioglass-tissue interaction with an improved cell attachment. Modified bioglass increases in vitro Alp activity and calcium accumulation, and also positively affects cell behavior by supporting cell adaptation. Bioglass exerts osteogenic potential in vivo especially during early bone healing.

Structural insight into the function of human peptidyl arginine deiminase 6

Peptidyl arginine deiminase 6 (PADI6 or PAD6) is vital for early embryonic development in mice and humans, yet its function remains elusive. PADI6 is less conserved than other PADIs and it is currently unknown whether it has a catalytic function. Here we show that human PADI6 dimerises like hPADIs 2–4, however, does not bind Ca2+ and is inactive in in vitro assays against standard PADI substrates. By determining the crystal structure of hPADI6, we show that hPADI6 is structured in the absence of Ca2+ where hPADI2 and hPADI4 are not, and the Ca-binding sites are not conserved. Moreover, we show that whilst the key catalytic aspartic acid and histidine residues are structurally conserved, the cysteine is displaced far from the active site centre and the hPADI6 active site pocket appears closed through a unique evolved mechanism in hPADI6, not present in the other PADIs. Taken together, these findings provide insight into how the function of hPADI6 may differ from the other PADIs based on its structure and provides a resource for characterising the damaging effect of clinically significant PADI6 variants.

Study on the Scale and Corrosion Inhibition Effect of Curcumin‐Based Novel Polymers

AbstractThe curcumin‐malic acid‐aspartic acid polymer (PCMA) as a new water treatment agent was prepared by solid phase synthesis of curcumin, malic acid and aspartic acid. The static scale inhibition experiments showed that PCMA can inhibit CaCO3 and CaSO4 scale formation by 100.0 % and had excellent scale inhibition effect under various experimental conditions. The mechanism of action of PCMA was obtained by X‐ray diffraction, scanning electron microscope and molecular dynamics simulation. Electrochemical test showed that PCMA is an anodic corrosion inhibitor that achieves 93.1 % corrosion inhibition by forming a protective film on the surface of Q235 carbon steel. Besides, fluorescence spectra proved that PCMA has stable fluorescence intensity.

A P450 superfamily member NtCYP82C4 promotes nicotine biosynthesis in Nicotiana tabacum

In plants, cytochrome P450s are monooxygenase that play key roles in the synthesis and degradation of intracellular substances. In tobacco, the majority of studies examining the P450 superfamily have concentrated on the CYP82E subfamily, where multiple family members function as demethylases, facilitating the synthesis of nornicotine. In this study, NtCYP82C4, a tobacco P450 superfamily member, was identified from a gene-edited tobacco mutant that nicotine biosynthesis in tobacco leaves is evidently reduced. Compared to the wild-type plants, the knockout of NtCYP82C4 resulted in a significantly lower nicotine content and biomass in tobacco leaves. Transcriptome and metabolome analyses indicated that the knockout of NtCYP82C4 inhibites secondary metabolic processes in tobacco plants, leading to the accumulation of some important precursors in the nicotine synthesis process, including aspartic acid and nicotinic acid, and increases nitrogen partitioning associated with those processes such as amino acid synthesis and utilization. It is speculated that NtCYP82C4 may function as an important catalase downstream of the nicotine synthesis. Currently, most of the steps and enzymes involved in the nicotine biosynthesis process in tobacco have been elucidated. Here, our study deepens the current understanding of nicotine biosynthesis process and provides new enzyme targets for nicotine synthesis in tobacco plants.

Renal Clearable H‐Dots Leveraging Ligand Complexation for Enhanced Active Tumor Targeting

The use of ligand conjugation onto nanoparticle surfaces as an active targeting strategy has gained significant attention in the pursuit of improving tumor‐specific delivery and retention. However, the chemical conjugation of targeting moieties often induces alterations in the physicochemical properties of nanoparticles, including size, conformation, charge‐to‐mass ratio, and hydrophilicity/lipophilicity, resulting in unexpected biodistribution and pharmacokinetic profiles. Here, the enhanced active targeting efficiency achieved by integrating cyclic arginine–glycine–aspartic acid (cRGD) peptides onto ultrasmall nanocarrier H‐dot while preserving its essential physicochemical and pharmacokinetic attributes is investigated. The resulting cRGD/H‐dots demonstrate improved cellular uptake via integrin αvβ3 receptors, accompanied by negligible cytotoxicity. Notably, the active targeting efficacy of cRGD/H‐dots compared to unmodified H‐dots (1.2%ID/g, two‐fold increase) is quantitatively evaluated, validated through fluorescence imaging and histological analysis. The findings highlight that cRGD/H‐dots offer enhanced tumor targetability and prolonged tumoral retention while maintaining active renal clearance of unbound molecules.