Aspartate Research Articles

Mechanistic Insights of Amino Acid Binding to Hydroxyapatite: Molecular Dynamics Charts Future Directions in Biomaterial Design.

Extensive efforts have been made to improve the understanding of hard tissue regeneration, essential for advancing medical applications like bone graft materials. However, the mechanisms of bone biomineralization, particularly the regulation of hydroxyapatite growth by proteins/peptides, remain debated. Small biomolecules such as amino acids are ideal for studying these mechanisms due to their simplicity and relevance as protein/peptide building blocks. This study investigates the binding affinity of four amino acids including glycine (Gly), proline (Pro), lysine (Lys), and aspartic acid (Asp) to the hydroxyapatite (HAP) (100) surface through molecular dynamics simulations. Our findings reveal that aspartic acid exhibits the most energetically favorable binding affinity, attributed to its additional carboxylate group (-COO-), which facilitates stronger interactions with Ca2+ ions on the HAP surface compared to other amino acids with single carboxylate groups. This highlights the critical role of specific functional groups in modulating binding strength, emphasizing that the presence of multiple binding sites in amino acids enhances binding stability. Interestingly, the study also uncovers the significance of water-mediated interactions, as the compact water layer above the HAP surface acts as a barrier, complicating direct binding and underscoring the need to consider solvation effects in simulations. Glycine, due to its small size, demonstrates a unique ability to penetrate this tightly bound water monolayer, suggesting that molecular size influences binding dynamics. These simulations offer detailed insights into the atomic-level interactions, providing a deeper understanding of binding affinity and stability. These insights are pertinent for designing peptides or proteins with enhanced interactions with biomaterials, particularly in mimicking natural bone-binding processes.

PAM-relaxed and temperature-tolerant CRISPR-Mb3Cas12a single transcript unit systems for efficient singular and multiplexed genome editing in rice, maize, and tomato.

Class 2 Type V-A CRISPR-Cas (Cas12a) nucleases are powerful genome editing tools, particularly effective in A/T-rich genomic regions, complementing the widely used CRISPR-Cas9 in plants. To enhance the utility of Cas12a, we investigate three Cas12a orthologs-Mb3Cas12a, PrCas12a, and HkCas12a-in plants. Protospacer adjacent motif (PAM) requirements, editing efficiencies, and editing profiles are compared in rice. Among these orthologs, Mb3Cas12a exhibits high editing efficiency at target sites with a simpler, relaxed TTV PAM which is less restrictive than the canonical TTTV PAM of LbCas12a and AsCas12a. To optimize Mb3Cas12a, we develop an efficient single transcription unit (STU) system by refining the linker between Mb3Cas12a and CRISPR RNA (crRNA), nuclear localization signal (NLS), and direct repeat (DR). This optimized system enables precise genome editing in rice, particularly for fine-tuning target gene expression by editing promoter regions. Further, we introduced Arginine (R) substitutions at Aspartic acid (D) 172, Asparagine (N) 573, and Lysine (K) 579 of Mb3Cas12a, creating two temperature-tolerant variants: Mb3Cas12a-R (D172R) and Mb3Cas12a-RRR (D172R/N573R/K579R). These variants demonstrate significantly improved editing efficiency at lower temperatures (22 °C and 28 °C) in rice cells, with Mb3Cas12a-RRR showing the best performance. We extend this approach by developing efficient Mb3Cas12a-RRR STU systems in maize and tomato, achieving biallelic mutants targeting single or multiple genes in T0 lines cultivated at 28 °C and 25 °C, respectively. This study significantly expands Cas12a's targeting capabilities in plant genome editing, providing valuable tools for future research and practical applications.

Enhancing De Novo Protein Sequencing through the C-Terminal Labeling Strategy: Resolving Isobaric Ambiguities by Electron-Transfer/Higher Energy Collision Dissociation (EThcD).

De novo protein sequencing via a bottom-up approach requires various proteases to produce overlapping peptides. However, peptides generated by proteases other than trypsin, LysC, and ArgC often yield C-terminal fragments with suboptimal ionization in positive mode mass spectrometry (MS). This study introduces a novel peptide labeling strategy that involves modifying peptides at the C-terminal and at the carboxyl groups of Aspartic and Glutamic acid with arginine methyl ester (R-met) to improve peptide fragmentation and resolve isobaric ambiguities encountered during sequencing. An amidation reaction is used with coupling reagents to conjugate R-met to the peptide's C-terminal end, introducing a functional group that enhances the detectability of C-terminal peptide fragment ions by mass spectrometry. Subsequently, selecting a charge state of +2 or higher can facilitate optimal fragmentation of the derivatized peptides using electron-transfer/higher energy collision dissociation (EThcD), thereby generating essential w-ions to resolve common isobaric ambiguities. Demonstrating this strategy across diverse protein types, including albumin and antibodies and using different proteases for digestion, highlights the unique characteristics of combining the proposed amidation reaction with the specific proteases tested.

Synthesis and Anti-Liver Fibrosis Research of Aspartic Acid Derivatives

Liver fibrosis plays an important role in the progression of liver disease, but there is a severe shortage of direct and efficacious pharmaceutical clinical interventions. Literature research indicates that aspartic acid exhibits hepatoprotective properties. In this paper, 32 target compounds were designed and synthesized utilizing aspartic acid as the lead compound, of which 22 were new compounds not reported in the literature. These compounds were screened for their inhibitory effects on the COL1A1 promoter to assess in vitro anti-liver fibrosis activity and summarized structure–activity relationships. Four compounds exhibited superior potency with inhibition rates ranging from 66.72% to 97.44%, substantially higher than EGCG (36.46 ± 4.64%) and L-Asp (11.33 ± 0.35%). In an LPS-induced inflammation model of LX-2 cells, both 41 and 8a could inhibit the activation of LX-2 cells, reducing the expression of COL1A1, fibronectin, and α-SMA. Upon further investigation, 41 and 8a ameliorated liver fibrosis by inhibiting the IKKβ-NF-κB signaling pathway to alleviate inflammatory response. Overall, the study evaluated the anti-liver fibrosis effects of aspartic acid derivatives, identified the potency of 41, and conducted a preliminary exploration of mechanisms, laying the foundation for the discovery of novel anti-liver fibrosis agents.

Copper-amino acid/Carboxymethyl starch composite for controllable releasing of povidone-iodine

Povidone-iodine is identified as one of the widely applicable antiseptic reagents for treatment of skin infection and wound healing. Controllable releasing of povidone-iodine is extensively required for healing of chronic wounds. The release of povidone-iodine was systematically studied from the composites based on carboxymethyl starch (CMS). Currently, different ratios from copper precursor and L-aspartic acid (L-AA) were interacted with CMS to obtain Cu-L-AA@CMS composites. Increment the percentage of L-AA was reflected in clustering of dense masses from the desirable composite with highly crystalline/stable structural network. Regardless to pH conditions, Cu-L-AA(30%)@CMS composite showed the highest efficiency for controllable release of povidone-iodine, whereas, the release percentages were estimated to be 58%, 32% and 18% at pH 5, 7 and 9, respectively. The kinetic results revealed the impossibility of povidone-iodine releasing via diffusion/erosion for further support of the hypothesis of releasing via swelling process. Moreover, the release of povidone-iodine using column technique showed that the lowest release was estimated at using high rate of 6 mL/min. Besides the biocompatibility and biodegradability of the prepared Cu-L-AA@CMS composites, it showed the superiority for controllable release of povidone-iodine antiseptic reagent to regulate its beneficial effect in curing of the skin.

Metabolomic analysis reveals potential role of immunometabolism dysregulation in recurrent pregnancy loss.

Recurrent pregnancy loss (RPL) affects women's reproductive health seriously, with immune dysfunction playing a key role in its cause, yet the exact mechanisms remain elusive. We aim to investigate potential mechanisms and identify biomarkers linked to RPL. Immune cytokine testing and metabolomic profiling were conducted on the serum of 34 RPL patients and 30 healthy individuals. The metabolic pathways of the differential metabolites were analyzed, and specific metabolites were validated through targeted profiling. Potential biomarkers were identified, and the relationships between immune cytokines and differential metabolites were explored. In the RPL group, serum interleukin-6 and interleukin-10 levels were significantly higher, while interleukin-2 and interferon-γ were significantly lower. A total of 296 differential metabolites were detected by untargeted metabolomic profiling between the RPL and control groups, with most linked to amino acid metabolism. Targeted metabolomic profiling of amino acid metabolism revealed upregulation of indole-3-acetic acid, tyrosine, glycine, isoleucine, tryptophan, lysine, aspartic acid, arginine, leucine, threonine, glutamic acid, cystine, and phenylpyruvic acid (PPA) in the RPL group. Moreover, PPA and 5-hydroxy-L-tryptophan showed great potential in predicting RPL in a diagnostic model. Cystine and tyrosine were associated with immune cytokines in correlation analysis. The study highlights the role of amino acid metabolism in RPL pathogenesis, suggesting that PPA and 5-HTP may be potential predictive indicators, while cystine and tyrosine may potentially regulate immune responses related to RPL. Further investigation into the molecular mechanisms underlying these findings could potentially result in the creation of novel diagnostic and therapeutic approaches for RPL.

Dynamic changes in aroma compounds and precursor substances during rice cooking

Cooking is a key process in forming cooked rice flavor, and more data on aroma compounds should be needed during rice cooking. This paper tracked dynamic changes in aroma compounds, sugars, amino acids, and fatty acids during cooking. After soaking, the content of glucose, fructose, oleic acid, and linoleic acid increased. In the hydrothermal cooking stage, glucose, aspartic acid, glutamic acid, and alanine increased significantly (p < 0.05), while fructose, oleic acid, and linoleic acid first increased and then decreased. In raw rice and soaked rice, alkanes and alkenes were the main volatile compounds, and the content of hydrocarbon compounds decreased in the hydrothermal cooking stage, and many aldehydes, alcohols, ketones, and furan compounds were generated. A total of 28 aroma compounds were sniffed by GC-O-MS, and 13 aroma compounds with OAV >1 were screened out. These results showed that raw rice and soaked rice had similar aroma characteristics and aroma precursor substances that mainly accumulated in the SO10 or ST10 stage, and hydrothermal cooking was the key process of rice aroma formation.

Self-aggregation effect of the ternary system “Alga EPS-DOM-HMs” and the characterization of the self-adaptation metabolic response of microalgae

Heavy metals (HMs) present in the natural aquatic environment can form a ternary aggregate of “EPS-DOM-HMs” with the prevalent microalgae extracellular polymers substances (EPS) and macromolecular dissolved organic matters (DOMs), which show special molecular structure and biological interaction. This study reveals the formation of “EPS-TA-HMs” and the mechanism of their physiological and metabolic effects on Raphidocelis subcapitata. Results indicate that TA-Cr(III) can bind to EPS to form ternary aggregates with substances coexisting large and small hydrodynamic diameters and that the interactions are dominated by hydrophobic interactions of the protein binding to the pyrrole ring of the polyphenol and hydrogen bonding interactions formed by OC–(N R O). The protein structure of EPS has the largest proportion of proline, glycine, aspartic acid, and tryptophan. These interactions promoted the secretion of EPS components and reduced the growth inhibition of Raphidocelis subcapitata by 45.9 % compared with Cr(III) exposure. TEM analysis combined with EDS analysis indicated that Cr(III) was taken intracellularly and TA-Cr(III) was not. In addition, metabolomics analyses revealed that microalgae initiate adaptive mechanisms via the activation of a two-component system (i.e., maintenance of high metabolic activity). This study underscored the morphology of HMs in real aquatic environments and the mechanisms of metabolic effects on aquatic organisms.

Phosphorylation of Ser711 residue in the hypervariable region of zoonotic genotype 3 hepatitis E virus is important for virus replication.

Hepatitis E virus (HEV) is distinct from other hepatotropic viruses because it is zoonotic. HEV-1 and HEV-2 exclusively infect humans, whereas HEV-3 and HEV-4 are zoonotic. However, the viral and/or host factors responsible for cross-species HEV transmission remain elusive. The hypervariable region (HVR) in HEV is extremely heterogenetic and is implicated in HEV adaptation. Here, we investigated the potential role of Serine phosphorylation in the HVR in HEV replication. We first analyzed HVR sequences across different HEV genotypes and identified a unique region at the N-terminus of the HVR, which is variable in the human-exclusive HEV genotypes but relatively conserved in zoonotic HEV genotypes. Using predictive tools, we identified four potential phosphorylation sites that are highly conserved in zoonotic HEV-3 and HEV-4 genomes but absent in human-exclusive HEV-1 strains. To explore the functional significance of these putative phosphorylation sites, we introduced mutations into the HEV-3 infectious clone and indicator replicon, replacing each Serine residue individually with alanine or aspartic acid, and assessed the impact of these substitutions on HEV-3 replication. We found that the phospho-blatant S711A mutant significantly reduced virus replication, whereas the phospho-mimetic S711D mutant modestly reduced virus replication. Conversely, mutations in the other three Serine residues did not significantly affect HEV-3 replication. Furthermore, we demonstrated that Ser711 phosphorylation did not alter host cell tropism of zoonotic HEV-3. In conclusion, our results showed that potential phosphorylation of the Ser711 residue significantly affects HEV-3 replication in vitro, providing new insights into the potential mechanisms of zoonotic HEV transmission.IMPORTANCEHEV is an important zoonotic pathogen, causing both acute and chronic hepatitis E and extrahepatic manifestation of diseases, such as neurological sequelae. The zoonotic HEV-3 is linked to chronic infection and neurological diseases. The specific viral and/or host factors facilitating cross-species HEV infection are unknown. The intrinsically disordered HVR in ORF1 is crucial for viral fitness and adaptation, both in vitro and in vivo. We hypothesized that phosphorylation of Serine residues in the HVR of zoonotic HEV by unknown host cellular kinases is associated with cross-species HEV transmission. In this study, we identified a conserved region within the HVR of zoonotic HEV strains but absent in the human-exclusive HEV-1 and HEV-2. We elucidated the important role of phosphorylation at the Ser711 residue in zoonotic HEV-3 replication, without altering the host cell tropism. These findings contribute to our understanding the mechanisms of cross-species HEV transmission.

Citric Acid by-Product Fermentation by Bacillus subtilis I9: A Promising Path to Sustainable Animal Feed

Citric acid by-products in animal feed pose a sustainability challenge. Bacillus species are commonly used for fermenting and improving the nutritional quality of feedstuffs or by-products. An experiment was conducted to enhance the nutritional value of citric acid by-products through fermentation with Bacillus subtilis I9 for animal feed. The experiment was carried out in 500 mL Erlenmeyer flasks with 50 g of substrate and 200 mL of sterile water. Groups were either uninoculated or inoculated with B. subtilis I9 at 107 CFU/mL. Incubation occurred at 37 °C with automatic shaking at 150 rpm under aerobic conditions for 0, 24, 48, 72, and 96 h. Inoculation with B. subtilis I9 significantly increased Bacillus density to 9.3 log CFU/mL at 24 h (p &lt; 0.05). CMCase activity gradually increased, reaching a maximum of 9.77 U/mL at 72 h. After 96 h of fermentation with inoculated B. subtilis I9, the citric acid by-product exhibited a significant decrease (p &lt; 0.05) in crude fiber by 10.86%, hemicellulose by 20.23%, and cellulose by 5.98%, but an increase in crude protein by 21.89%. Gross energy decreased by 4% after inoculation with B. subtilis in comparison to the uninoculated control (p &lt; 0.05). Additionally, the non-starch polysaccharide (NSP) degradation due to inoculation with B. subtilis I9 significantly reduced (p &lt; 0.05) NSP by 24.37%, while galactose, glucose, and uronic acid decreased by 22.53%, 32.21%, and 18.11%, respectively. Amino acid profile content increased significantly by more than 12% (p &lt; 0.05), including indispensable amino acids such as histidine, isoleucine, lysine, methionine, phenylalanine, tryptophan, and valine and dispensable amino acids like alanine, aspartic acid, glutamic acid, glutamine, glycine, proline, and tyrosine. Furthermore, citric acid by-products inoculated with B. subtilis I9 exhibited changes in the cell wall structure under scanning electron microscopy, including fragmentation and cracking. These results suggest that fermenting citric acid by-products with B. subtilis I9 effectively reduces dietary fiber content and improves the nutritional characteristics of citric acid by-products for use in animal feed.

Defect-Engineered MOF-801/Sodium Alginate Aerogel Beads for Boosting Adsorption of Pb(II).

Metal-organic frameworks (MOFs) are attractive adsorbents for heavy metal capture due to their superior stability, easy modification, and adjustable pore size. However, their inherent microporous structure poses challenges in achieving a higher adsorption capacity. Defect engineering is considered a simple method to create hierarchical MOFs with larger pores. Here, we employed l-aspartic acid as a mixed linker to bind Zr4+ clusters in competition with fumaric acid of MOF-801 to create defects, and the pore size was increased from 4.66 to 15.65 nm. Mercaptosuccinic acid was subsequently used as a postexchange ligand to graft the resultant MOF-801 by acid-ammonia condensation to further expand the pore size to 22.73 nm. Notably, the -NH2, -COOH, and -SH groups contributed by these two ligands increased the adsorption sites for Pb(II). The obtained defective MOF-801 with larger pores was thereafter loaded onto sodium alginate to form aerogel beads as adsorbents, and an adsorption capacity of 375.48 mg/g for Pb(II) was achieved, which is ∼51 times that of pristine MOF-801. The aerogel beads also exhibited outstanding reusability with a removal efficiency of ∼90.23% after 5 cycles of use. The adsorption mechanism of Pb(II) included ion-exchange interaction, as well as chelation interactions of Pb-O, Pb-NH2, and Pb-S. The versatile combination of defect engineering and composite beads provides novel inspirations for MOF modification for boosting heavy metal adsorption.

Kinetic studies of AST isoenzymes I,II,III,IV partially purified from patient,s urine with chroinc renal failure

In this research, the kinetic studies of four isoenzymes of Asprtate aminotransferase, which partially purified from the urine of chronic renal failure patients were carried out .The four isoenzymes were obeyed Michaelis-Menton's equation and the optimum concentration of their substrate (Aspartic acid) was (166.5x10-3) mole/liter,and their Km values were determined. Four isoenzymesI,II,III,IV have shown an optimum pH at 7.4.The four isoenzymes obeyed Arrhenius equation up to 37º C and their Ea and Q10 constants were determined .

Identification of Peptide Binding Motifs for Calcium Sulfate Hemihydrate using Phage Display.

Selective control over crystallization in complex multicomponent systems such as hydrating cements is a key issue in modern material science. In this context, rational selection-based approaches appear highly promising in the quest for new additive chemistries. Here we have used phage display to identify peptide structures showing high affinity to adsorb on the surfaces of calcium sulfate hemihydrate (also referred to as bassanite), an important hydraulic binder employed in large scales by the construction industry. The results suggest a triplet of amino acids consisting of aspartic acid, serine and leucine, to maintain strong interactions with the surfaces of hemihydrate particles. This notion is confirmed by actual hydration experiments, in which the identified peptide motif provides strictly selective effects during the transformation of bassanite into more stable gypsum. Our work thus contributes to a better understanding of hydraulic binders and their required improvement for a sustainable future.

Morpholine Prevents the Formation of Aspartimide from β-allyl ester aspartic acid during Fmoc Cleavage in SPPS of Stapled Peptides

Morpholine Prevents the Formation of Aspartimide from β-allyl ester aspartic acid during Fmoc Cleavage in SPPS of Stapled Peptides

Influence of Asparaginase on Acrylamide Content, Color, and Texture in Oat, Corn, and Rice Cookies.

The safety of cereal-based baked goods can be compromised by acrylamide, a processing contaminant and class 2A carcinogen. One method to prevent acrylamide formation is by converting asparagine to aspartic acid using asparaginases. Four different asparaginases were tested using two dough incubation temperatures and dosages for oat, corn, and rice cookies. To evaluate the impact of asparaginases on product quality, color and texture were measured. Acrylamide was reduced by up to 97, 95, and 92% for oat, corn, and rice cookies, respectively, compared to the control. Asparaginase treatment resulted in minor changes in color and texture. There was a strong correlation between acrylamide concentrations in cookies and the free asparagine content of the flour. By minimizing the formation of acrylamide while maintaining product quality, the use of asparaginases offers a promising approach to enhancing food safety standards and protecting public health, potentially influencing regulatory guidelines and consumer preferences.

The 419th Aspartic Acid of Neural Membrane Protein Enolase 2 Is a Key Residue Involved in the Axonal Growth of Motor Neurons Mediated by Interaction between Enolase 2 Receptor and Extracellular Pgk1 Ligand

Neuron-specific Enolase 2 (Eno2) is an isozyme primarily distributed in the central and peripheral nervous systems and neuroendocrine cells. It promotes neuronal survival, differentiation, and axonal regeneration. Recent studies have shown that Eno2 localized on the cell membrane of motor neurons acts as a receptor for extracellular phosphoglycerate kinase 1 (ePgk1), which is secreted by muscle cells and promotes the neurite outgrowth of motor neurons (NOMN). However, interaction between Eno1, another isozyme of Enolase, and ePgk1 failed to return the same result. To account for the difference, we constructed seven point-mutations of Eno2, corresponding to those of Eno1, and verified their effects on NOMN. Among the seven Eno2 mutants, eno2-siRNA-knockdown NSC34 cells transfected with plasmid encoding the 419th aspartic acid mutated into serine (Eno2-[D419S]) or Eno2-[E420K] showed a significant reduction in neurite length. Moreover, the Eno2-ePgk1-interacted synergic effect on NOMN driven by Eno2-[D419S] was more profoundly reduced than that driven by Eno2-[E420K], suggesting that D419 was the more essential residue involved in NOMN mediated by Eno2-ePgk1 interaction. Eno2-ePgk1-mediated NOMN appeared to increase the level of p-Cofilin, a growth cone collapse marker, in NSC34 cells transfected with Eno2-[D419S] and incubated with ePgk1, thereby inhibiting NOMN. Furthermore, we conducted in vivo experiments using zebrafish transgenic line Tg(mnx1:GFP), in which GFP is tagged in motor neurons. In the presence of ePgk1, the retarded growth of axons in embryos injected with eno2-specific antisense morpholino oligonucleotides (MO) could be rescued by wobble-eno2-mRNA. However, despite the addition of ePgk1, the decreased defective axons and the increased branched neurons were not significantly improved in the eno2-[D419S]-mRNA-injected embryos. Collectively, these results lead us to suggest that the 419th aspartic acid of mouse Eno2 is likely a crucial site affecting motor neuron development mediated by Eno2-ePgk1 interaction, and, hence, mutations result in a significant reduction in the degree of NOMN in vitro and axonal growth in vivo.

Effects of complex probiotics on intestinal function and its regulatory mechanism in patients with constipation.

Chronic constipation is a multi-symptomatic, multifactorial, and heterogeneous gastrointestinal disorder. Current pharmacological treatments for chronic constipation are limited and might negatively impact the patients' quality of life. Although probiotics have been shown to improve constipation symptoms, their specific regulatory mechanisms remain unclear. This study sought to explore how probiotic complexes may affect chronic constipation by improving patients' defecation habits. Furthermore, microbial profiles and non-targeted metabolites were assessed to explore the metabolic pathways involved in the improvement of constipation by probiotics. Patients with chronic constipation were treated using a single-blind, randomised, placebo-controlled trial design. The experimental group was administered Lactobacillus powder prepared from 15 probiotic products, and maltodextrin was used as a placebo. Samples were collected twice daily for 4 weeks, and faecal samples were analysed using 16S rRNA sequencing and untargeted metabolic histology. Probiotic treatment changed the makeup of the gut microbiota, enhanced the quantity of Bifidobacterium and Lactobacillus, and markedly reduced clinical symptoms. The 16S rRNA analysis revealed that the abundance of Bifidobacterium and Prevotella increased while that of Thickettsia declined. Moreover, there was a decrease in the abundance of Faecalibacterium and Roseburia. Non-targeted metabolomics analysis identified several differential metabolites, including succinic acid, fumaric acid, cholesterol, xanthurenic acid, 3-alpha,7-alpha-trihydroxy-5beta-cholestan-26-oic, and N-methyltryptamine. KEGG analysis showed that these metabolites were mainly associated with metabolic pathways such as primary bile acid biosynthesis, tryptophan metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism, cholesterol metabolism, and propanoate metabolism. In this study, gut microbiome and non-targeted metabolome analyses were performed on collected faecal samples to compare characteristic microorganisms and differential metabolites to provide new insights and references for probiotic intervention in constipation. Trial registered at chictr.org.cn under number: ChiCTR2200056274.

Schisandrin A alleviates non-alcoholic fatty liver disease by improving liver metabolic disorders and suppressing the GSK3β signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is a clinical pathological syndrome characterized by excessive fat deposition in liver cells, posing a new challenge in the field of contemporary medicine. Schisandrin A (SchA) is a lignan derived from the fruit of Schisandra chinensis, a functional food and also a traditional herbal medicine known for its hepatic protective effects. The study aims to identify potential target and regulation mechanism of SchA on NAFLD treatment. Metabolomics analysis revealed that SchA improved the abnormal metabolic profile of the liver in NAFLD mice. In addition to ameliorating lipid metabolism, SchA showed potential in elevating the levels of amino acids such as L-tryptophan, beta-alanine, L-aspartic acid, and L-tyrosine, which were deficient in NAFLD mouse livers, as well as restored the metabolism of abnormal vitamins like vitamin B6. Network pharmacology research and molecular docking suggested that GSK3β was a direct target of SchA, which was experimentally validated as well. These findings highlight the potential value of the active component SchA from Schisandra chinensis in the prevention and treatment of NAFLD.

Substrate preference of Tetrasphaera in dual PAOs synergistic EBPR system and its phosphorus removal performance

In this study, an alternated anaerobic/aerobic sequencing batch reactor (SBR) was employed to investigate the effect of the substrate conversion from casein hydrolysate (Cas aa) to a mixture of amino acids (glutamate, aspartate, glycine and proline) on the efficacy of nitrogen and phosphorus removal in an enhanced biological phosphorus removal (EBPR) system characterized by dual polyphosphate-accumulating organisms (PAOs), mainly focusing on the substrate preference of fermentative PAOs. The results indicated that a stable removal efficiency was found to be above 90 % as the substrate was converted to the mixture of amino acids. Meanwhile, the removal efficiency of ammonium eventually increased to over 95 % in stage III, despite an increase of ammonia nitrogen by hydrolysis with the rising proportion of mixed amino acids in influent. Moreover, shortening the anaerobic duration did not significantly affect the phosphorus removal performance, even enhancing anaerobic phosphorus release capacity. Nevertheless, the ammonia nitrogen removal was influenced. 16 s rRNA high-throughput sequencing results demonstrated that the detected fermentative PAO like Tetrasphaera in the EBPR system exhibited a clear preference for utilizing mixed amino acids and could cooperate with traditional PAO like Accumulibacter for phosphorus removal. In addition, the fermentation of amino acids mixture by Tetrasphaera was more pronounced and its abundance increased under the condition of a shorter anaerobic duration, leading to a relatively stable and high abundance of Accumulibacter in the presence of sufficient substrates from Tetrasphaera. However, considering the nitrogen removal performance and steady operation of the EBPR system, a longer anaerobic duration was more reasonable.

Electrostatic Preorganization in Three Distinct Heterogeneous Proteasome β-Subunits.

The origin of the enzyme's powerful role in accelerating chemical reactions is one of the most critical and still widely discussed questions. It is already accepted that enzymes impose an electrostatic field onto their substrates by adopting complex three-dimensional structures; therefore, the preorganization of electric fields inside protein active sites has been proposed as a crucial contributor to catalytic mechanisms and rate constant enhancement. In this work, we focus on three catalytically active β-subunits of 20S proteasomes with low sequence identity (∼30%) whose active sites, although situated in an electrostatically miscellaneous environment, catalyze the same chemical reaction with similar catalytic efficiency. Our in silico experiments reproduce the experimentally observed equivalent reactivity of the three sites and show that obliteration of the electrostatic potential in all active sites would deprive the enzymes of their catalytic power by slowing down the chemical process by a factor of 1035. To regain enzymatic efficiency, besides catalytic Thr1 and Lys33 residues, the presence of aspartic acid in position 17 and an aqueous solvent is required, proving that the electrostatic potential generated by the remaining residues is insignificant for catalysis. Moreover, it was found that the gradual decay of atomic charges on Asp17 strongly correlates with the enzyme's catalytic rate deterioration as well as with a change in the charge distributions due to introduced mutations. The computational procedure used and described here may help identify key residues for catalysis in other biomolecular systems and consequently may contribute to the process of designing enzyme-like synthetic catalysts.