Exploring the constitutive activation mechanism of the class A orphan GPR20.

GPR20, an orphan G protein-coupled receptor (GPCR), shows significant expression in intestinal tissue and represents a potential therapeutic target to treat gastrointestinal stromal tumors. GPR20 performs high constitutive activity when coupling with Gi. Despite the pharmacological importance of GPCR constitutive activation, determining the mechanism has long remained unclear. In this study, we explored the constitutive activation mechanism of GPR20 through large-scale unbiased molecular dynamics simulations. Our results unveil the allosteric nature of constitutively activated GPCR signal transduction involving extracellular and intracellular domains. Moreover, the constitutively active state of the GPR20 requires both the N-terminal cap and Gi protein. The N-terminal cap of GPR20 functions like an agonist and mediates long-range activated conformational shift. Together with the previous study, this study enhances our knowledge of the self-activation mechanism of the orphan receptor, facilitates the drug discovery efforts that target GPR20.

Branched Aluminum Nanocrystals with Internal Hot Spots: Synthesis and Single-Particle Surface-Enhanced Raman Scattering.

Owing to their unique and sustainable surface plasmonic properties, Al nanocrystals have attracted increasing attention for plasmonic-enhanced applications, including single-particle surface-enhanced Raman scattering (SERS). However, whether Al nanocrystals can achieve single-particle SERS is still unknown, mainly due to the synthetic difficulty of Al nanocrystals with internal gaps. Herein, we report a regrowth method for the synthesis of Al nanohexapods with tunable and uniform internal gaps for single-particle SERS with an enhancement factor of up to 1.79 × 108. The uniform branches of the Al nanohexapods can be systematically tuned regarding their dimensions, terminated facets, and internal gaps. The Al nanohexapods generate hot spots concentrated in the internal gaps due to the strong plasmonic coupling between the branches. A single-particle SERS measurement of Al nanohexapods shows strong Raman signals with maximum enhancement factors comparable to that of Au counterparts. The large enhancement factor indicates that Al nanohexapods are good candidates for single-particle SERS.

Pan-KRAS inhibitors suppress proliferation through feedback regulation in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is currently one of the most lethal cancers worldwide. Several basic studies have confirmed that Kirsten rat sarcoma virus (KRAS) is a key driver gene for the occurrence of PDAC, and KRAS mutations have also been found in most patients in clinical studies. In this study, two pan-KRAS inhibitors, BI-2852 and BAY-293, were chosen as chemical probes to investigate their antitumor potency in PDAC. Their inhibitory effects on KRAS activation were validated in vitro and their antiproliferative potency in PDAC cell lines were profiled, with half-maximal inhibitory concentration (IC50) values of approximately 1 µM, demonstrating the therapeutic potential of pan-KRAS inhibitors in the treatment of PDAC. However, feedback regulation in the KRAS pathway weakened inhibitor activity, which was observed by a 50 times difference in BAY-293 from in vitro activity. Furthermore, pan-KRAS inhibitors effectively inhibited cell proliferation in 3D organoids cultured from PDAC patient samples; however, there were some variations between individuals. These results provide a sufficient theoretical foundation for KRAS as a clinical therapeutic target and for the application of pan-KRAS inhibitors in the treatment of PDAC, with important scientific significance in translational medicine.

In Situ Seed-Mediated Growth of Polymer-Grafted Gold Nanoparticles.

We report a facile yet general in situ seed-mediated method for the synthesis of polymer-grafted gold nanoparticles with narrow size distributions (<10%), accurately tunable sizes, and excellent colloidal stability. This method can be extended to a broad range of types and molecular weights of polymer ligands. Nanoparticles with different shapes can also be prepared by using preformed shaped nanoparticles directly as the seeds.

A Novel Multilayered RFID Tagged Cargo Integrity Assurance Scheme.

To minimize cargo theft during transport, mobile radio frequency identification (RFID) grouping proof methods are generally employed to ensure the integrity of entire cargo loads. However, conventional grouping proofs cannot simultaneously generate grouping proofs for a specific group of RFID tags. The most serious problem of these methods is that nonexistent tags are included in the grouping proofs because of the considerable amount of time it takes to scan a high number of tags. Thus, applying grouping proof methods in the current logistics industry is difficult. To solve this problem, this paper proposes a method for generating multilayered offline grouping proofs. The proposed method provides tag anonymity; moreover, resolving disputes between recipients and transporters over the integrity of cargo deliveries can be expedited by generating grouping proofs and automatically authenticating the consistency between the receipt proof and pick proof. The proposed method can also protect against replay attacks, multi-session attacks, and concurrency attacks. Finally, experimental results verify that, compared with other methods for generating grouping proofs, the proposed method can efficiently generate offline grouping proofs involving several parties in a supply chain using mobile RFID.

[Distribution Characteristics, Ecological Risk Assessment, and Source Tracing of Heavy Metals in the Sediments of Typical Lakes in the Middle Reaches of the Yangtze River].

In this study, surface sediment samples were collected from Dongting Lake, Honghu Lake, and Chihu Lake, and the concentrations of 10 heavy metals were measured. Then, the potential risk of heavy metal accumulation was evaluated using the cumulative pollution index (Igeo), the enrichment factor (EF), and the potential ecological risk index (RI), and the sources were traced using correlation analysis (Pearson) and principal component analysis (PCA). The results showed that the pollution and potential ecological risk of Cd were the most serious. The mean values of Cd in East Dongting Lake, Honghu Lake, and Chihu Lake were 2.85, 1.59, and 3.57 mg·kg-1, respectively. The concentrations of Cd were 25.87, 11.36, and 37.58 times higher than the soil background values of the corresponding provinces, which exceeded the risk screening value (0.6 mg·kg-1). Particularly, the Cd concentration of Chihu Lake exceeded the risk control value (3.0 mg·kg-1). Besides Cd, the concentration of As in Honghu Lake was also of concern. At the same time, the Cu, As, Zn, and Pb in Chihu Lake should not be neglected. The potential ecological risks of the three lakes were ranked as follows:Chihu Lake (RI=1 127)>East Dongting Lake (RI=831)>Honghu Lake (RI=421). The primary sources of heavy metals were industrial mining, agricultural production, and aquaculture, and some heavy metals (Mn and Cu) were from natural sources. This study was of great significance for the prevention and control of heavy metals in the sediments of typical lakes in the middle reaches of the Yangtze River.

Combined inhibitory effects of microcystin-LR and microcystin-RR on growth and development in zebrafish larvae.

Microcystins (MCs) are the most widespread, frequently found, and seriously toxic cyanobacterial toxins in aquatic environments. Microcystin-leucine-arginine (MCLR) and microcystin-arginine-arginine (MCRR) are the most studied MCs. Normally, their levels are low and they coexist in the environment; however, they may also interact with each other. The developmental toxicity of MCLR in the presence of MCRR in the early life stage of zebrafish (from 2 to 120 h post fertilization) was investigated for the first time in this study. Our findings revealed that MCRR treatment marginally elevated thyroxine (T4) and 3,5,3'-triiodothyronine (T3) levels, whereas MCLR treatment alone resulted in a significant increase in T3 and T4 levels, indicating a cooperative effect. Furthermore, clear changes in the expression levels of genes involved in growth and development, accompanied by growth inhibition, were observed after co-treatment with MCRR and MCLR. In addition, zebrafish larvae subjected to MCRR and/or MCLR treatment showed increased levels of superoxide dismutase, glutathione, and malondialdehyde, and decreased levels of catalase in the MCRR + MCLR group, indicating oxidative stress and lipid peroxidation. Thus, we investigated the synergistic developmental toxicity of MCRR and MCLR during the early life stages of zebrafish development.

How calcium inhibits the magnesium-dependent kinase gsk3ß: a molecular simulation study.

Glycogen synthase kinase 3ß (GSK3ß) is a ubiquitous serine/threonine kinase that plays a pivotal role in many biological processes. GSK3ß catalyzes the transfer of γ-phosphate of ATP to the unique substrate Ser/Thr residues with the assistance of two natural activating cofactors Mg(2+). Interestingly, the biological observation reveals that a non-native Ca(2+) ion can inhibit the GSK3ß catalytic activity. Here, the inhibitory mechanism of GSK3ß by the displacement of native Mg(2+) at site 1 by Ca(2+) was investigated by means of 80 ns comparative molecular dynamics (MD) simulations of the GSK3ß···Mg(2+)-2/ATP/Mg(2+) -1 and GSK3ß···Mg(2+)-2/ATP/Ca(2+)-1 systems. MD simulation results revealed that using the AMBER point charge model force field for Mg(2+) was more appropriate in the reproduction of the active site architectural characteristics of GSK3ß than using the magnesium-cationic dummy atom model force field. Compared with the native Mg(2+) bound system, the misalignment of the critical triphosphate moiety of ATP, the erroneous coordination environments around the Mg(2+) ion at site 2, and the rupture of the key hydrogen bond between the invariant Lys85 and the ATP O(ß2) atom in the Ca(2+) substituted system were observed in the MD simulation due to the Ca(2+) ion in active site in order to achieve its preferred sevenfold coordination geometry, which adequately abolish the enzymatic activity. The obtained results are valuable in understanding the possible mechanism by why Ca(2+) inhibits the GSK3ß activity and also provide insights into the mechanism of Ca(2+) inhibition in other structurally related protein kinases.

[Spectral Characteristics and Source Analysis of Chromophoric Dissolved Organic Matter in Surface Water of Taihu Lake Before Cyanobacterial Blooming].

Chromophoric dissolved organic matter (CDOM) is an important part of the nutrient biogeochemical cycle in aquatic ecosystems. To explore the characteristics and sources of CDOM components in the surface water of Taihu Lake, UV-visible spectroscopy and excitation emission matrix fluorescence spectroscopy-parallel factor analysis were used to analyze CDOM components in surface water. Combined with CDOM optical parameters (a355, SUVA254, a250/a365, FI, BIX, and HIX), the spatial differences and pollution sources were identified, and a preliminary comparison was made between this study and the historical data of CDOM components in Taihu Lake. According to the results, a355, SUVA254, and a250/a365 showed the characteristics of high concentration, high aromatic ability, and low relative molecular weight of CDOM in the surface water of the eastern part of Taihu Lake; however, the northern part showed the opposite characteristics. Four components were isolated from CDOM using parallel factor analysis:one tyrosine-like (C1), two types of tryptophan (C2 and C4), and one fulionic acid (C3). The main component C1 had a strong linear relationship with the C2 and C3 components, suggesting that different components originated from similar pollution sources. The fluorescence index showed that CDOM in different areas of Taihu Lake were differently affected by endogenous and terrestrial inputs; however, the overall humification degree was low. This indicated that the CDOM components in Taihu Lake were primarily protein-like (C1, C2, and C4) (>85%) and autogenous, with good biochemical availability.

Effect of double mutations K214/A-E215/Q of FRATide on GSK3ß: insights from molecular dynamics simulation and normal mode analysis.

Glycogen synthase kinase 3ß (GSK3ß) is a multifunctional serine/threonine protein kinase that is involved in several biological processes including insulin and Wnt signaling pathways. The Wnt signaling via FRAT-mediated displacement of axin inhibits GSK3ß activity toward non-primed substrates without affecting its activity toward primed substrates. Herein, molecular dynamics simulation, molecular mechanics generalized Born/surface area (MM_GBSA) calculation, and normal mode analysis are performed to explore the structural influence of the double mutations K214/A-E215/Q of FRATide on the GSK3ß-FRATide complex. The results reveal that the priming phosphate-binding site, the primed substrate-binding site, the alignment of the critical active site residues in the ATP-binding site, as well as the periodic open-closed conformational change of the ATP-binding site, which are critical for the catalytic activity of GSK3ß, are negligibly influenced in the mutated system compared with the wild-type (WT) system. This indicates that FRATide does not inhibit the GSK3ß activity toward primed substrates. Additionally, MM_GBSA calculation indicates that the less energy-favorable GSK3ß-FRATide complex is observed in the mutant than in the WT complex.

[Distribution Characteristics and Ecological and Health Risk Assessment of Phthalic Acid Esters in Surface Water of Qiandao Lake, China].

In order to reveal the pollution and risk level of phthalic acid esters (PAEs) in Qiandao Lake, six types of PAEs in 17 sampling points (in Qiandao Lake and its inflowing rivers) in dry and wet seasons were detected. The results showed that six types of PAEs were detected in both dry and wet seasons, with the concentrations of 0.98-5.33 µg·L-1 (average concentration 2.63 µg·L-1) in the dry season and 3.22-17.88 µg·L-1 (average concentration 7.99 µg·L-1) in the wet season. In terms of the detection rate and concentration of each monomer PAEs, DiBP, DBP, and DEHP were the main PAEs components in the water body. The measured value of DBP at 10 sampling points and its average mass concentration in the wet season were higher than the national standard (3 µg·L-1). Principal component analysis indicated that the main sources of PAEs were personal care products, plastics, and domestic waste. The pollution level of PAEs in Qiandao Lake was at a high level at home and abroad. The health risk assessment results in Qiandao Lake showed that the non-carcinogenic risk index of PAEs in the study area was less than 1, which would not produce non-carcinogenic risks to the human body. The carcinogenic risk index of children exceeded 10-6 at some points, indicating that it may pose carcinogenic risks to children, to which more attention should be paid.

[Analysis of Heavy Metal Pollution Characteristics and Potential Ecological Risks of Surface Sediments in Dongjiang Lake].

To understand the pollution characteristics, spatial distribution characteristics, potential ecological risks, and sources of heavy metals in surface sediments of Dongjiang Lake, 12 surface sediment samples were collected from Dongjiang Lake. The contents of 20 heavy metals including Li, Be, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Ag, Cd, Cs, Ba, Pb, and U were analyzed in this study. The geo-accumulation index method and potential risk index method were used to evaluate the pollution degree and potential risks of heavy metals in sediments, and the correlation analysis and principal component analysis were used to trace the source of the primary heavy metals. The results showed that the average contents of ω(Cd)(2.25 mg·kg-1) and ω(As)(80.80 mg·kg-1) in heavy metals of Dongjiang Lake sediments were 21.2 times and 5.5 times the background value (0.11 mg·kg-1 and 14.7 mg·kg-1) of Hunan province. The overall spatial distribution of heavy metals was in the order of South>North>Central. The evaluation by the geo-accumulation index method showed that Cd was at the heavy pollution level, As and Se were at the moderate pollution level, Ag and Ga were at the light pollution level, and the other heavy metals were below the pollution standard. The evaluation by the potential risk index showed that all the surface sediments of Dongjiang Lake were at the high-risk level. The main environmental risk factor was Cd, which had an extremely high risk; the second was As, which had a medium risk; and the remaining heavy metals had no ecological risk.

Role of bridging water molecules in GSK3ß-inhibitor complexes: insights from QM/MM, MD, and molecular docking studies.

The role of water molecules is increasingly gaining interest in drug design, and several studies have highlighted their paramount contributions to the specificity and the affinity of ligand binding. In this study, we employ the two-layer ONIOM-based quantum mechanics/molecular mechanics (QM/MM) calculations, molecular dynamics (MD) simulations, and molecular docking studies to investigate the effect of bridging water molecules at the GSK3ß-inhibitors interfaces. The results obtained from the ONIOM geometry optimization and AIM analysis corroborated the presence of bridging water molecules that form hydrogen bonds with protein side chain of Thr138 and/or backbone of Gln185, and mediate interactions with inhibitors in the 10 selected GSK3ß-inhibitor complexes. Subsequently, MD simulations carried out on a representative system of 1R0E demonstrated that the bridging water molecule is stable at the GSK3ß-inhibitor interface and appears to contribute to the stability of the protein-inhibitor interactions. Furthermore, molecular docking studies of GSK3ß-inhibitor complexes indicated that the inhibitors can increase binding affinities and the better docked conformation of inhibitors can be obtained by inclusion of the bridging water molecules, especially for the flexible inhibitors, in docking experiments into individual protein conformations. Our results elucidate the importance of bridging water molecules at the GSK3ß-inhibitor interfaces and suggest that they might prove useful in rational drug design.

Molecular modeling and molecular dynamics simulation studies of the GSK3ß/ATP/substrate complex: understanding the unique P+4 primed phosphorylation specificity for GSK3ß substrates.

Substrate specificity of protein kinases is of fundamental importance for the integrity and fidelity of signaling pathways. Glycogen synthase kinase 3ß (GSK3ß) has a unique substrate specificity that prefers phosphorylation of its substrates at the P+4 serine before it can further phosphorylate the substrate at the P0 serine in the canonical motif SXXXS(p), where S(p) is the primed phosphorylation site. The detailed phosphorylation mechanism, however, is not clearly understood. In this study, a three-dimensional (3D) model of the ternary complex of GSK3ß, ATP, and the phosphorylated glycogen synthase (pGS), termed GSK3ß/ATP/pGS, is constructed using a hierarchical approach and by integrating molecular modeling and molecular dynamics (MD) simulations. Based on the 3D model, the substrate primed phosphorylation mechanism is investigated via two 12 ns comparative MD simulations of the GSK3ß/ATP/pGS and GSK3ß/ATP/GS systems, which differ in the phosphate group bound to the P+4 serine of GS. In agreement with structural analysis, computed binding free energies reveal that the binding of pGS to GSK3ß is favored in the prephosphorylated state compared with the GS native state. More importantly, comparison with the system simulated without primed phosphorylation in the GSK3ß/ATP/GS complex shows that for an optimal phosphorylation reaction to occur, the pGS priming phosphate in the GSK3ß/ATP/pGS system optimizes the proper orientation of the GSK3ß N- and C-terminal domains and clamps the P0 serine of pGS in the appropriate configuration for interaction with the ATP γ-phosphate within the catalytic groove.

Dissection of the difference between the group I metal ions in inhibiting GSK3ß: a computational study.

Glycogen synthase kinase 3ß (GSK3ß) is a serine/threonine kinase that requires two cofactor Mg(2+) ions for catalysis in regulating many important cellular signals. Experimentally, Li(+) is a competitive inhibitor of GSK3ß relative to Mg(2+), while this mechanism is not experienced with other group I metal ions. Herein, we use native Mg(2)(2+)-Mg(1)(2+) GSK3ß and its Mg(2)(2+)-M(1)(+) (M = Li, Na, K, and Rb) derivatives to investigate the effect of metal ion substitution on the mechanism of inhibition through two-layer ONIOM-based quantum mechanics/molecular mechanics (QM/MM) calculations and molecular dynamics (MD) simulations. The results of ONIOM calculations elucidate that the interaction of Na(+), K(+), and Rb(+) with ATP is weaker compared to that of Mg(2+) and Li(+) with ATP, and the critical triphosphate moiety of ATP undergoes a large conformational change in the Na(+), K(+), and Rb(+) substituted systems. As a result, the three metal ions (Na(+), K(+), and Rb(+)) are not stable and depart from the active site, while Mg(2+) and Li(+) can stabilize in the active site, evident in MD simulations. Comparisons of Mg(2)(2+)-Mg(1)(2+) and Mg(2)(2+)-Li(1)(+) systems reveal that the inline phosphor-transfer of ATP and the two conserved hydrogen bonds between Lys85 and ATP, together with the electrostatic potential at the Li(1)(+) site, are disrupted in the Mg(2)(2+)-Li(1)(+) system. These computational results highlight the possible mechanism why Li(+) inhibits GSK3ß.

[Screening of Priority Pollutants and Risk Assessment for Surface Water from Shengjin Lake].

Shengjin Lake, which serves as an important National Nature Reserve, is suffering from chemical pollution due to rapid industrial and agricultural development in the circumjacent basin. Therefore, 168 anthropogenic toxic chemicals were determined to examine their spatial distribution and identify priority pollutants using a ranking system based on occurrence(O), persistence(P), bioaccumulation(B), ecological risk(E), and human health risk(H). Ecosystem and human health risks were also assessed. The spatial distribution of pollutants indicated that higher concentrations occur in the upper lake area compared to the middle and lower lake areas because of Jiang Dam. According to the derived priority pollutant list, phthalate esters(PAEs), organochlorine pesticides(OCPs), and heavy metals(HMs) are high-priority pollutants; polychlorinated biphenyls(PCBs), polycyclic aromatic hydrocarbons(PAHs), and volatile organic compounds(VOCs) are medium-priority pollutants; and antibiotics(ANTs) are low-priority pollutants. The ecology risk quotient(RQ) of the high-priority pollutants ranged from 4.3 to 15.9, indicating severe ecology risk to the aquatic organism, and higher risks were found in the upper lake areas. Additionally, the human health risk assessment revealed negligible carcinogenic risks associated with high-priority pollutants. The comprehensive ranking system established in this study can be applied to other lake basins by altering the measured concentrations to screen for priority pollutants, offering a scientific foundation for identifying priority control pollutants for watershed management.

[Repression of Nitrogen and Phosphorus Release from Lakeshore Sediment by Five Littoral-zone Plants].

The article researched the effect of Iris pseudacorus L.,Paspalum distichum L.,Leersia hexandra Swartz,Ludwigia peploides and Hydrocotyle vulgaris on the nitrogen and phosphorus repression in sandy soil from lower reaches of Yangtze River and clay from stored littoral zone. The result indicated that plants had a significant inhibitory effect on total phosphorus release from sediment, with concentration in overlaying water below 0.02 mg·L-1 in Paspalum distichum L., Hydrocotyle vulgaris, Iris pseudacorus group, below 0.03 mg·L-1 in Leersia hexandra Swartz, Ludwigia peploides group; with release rate below 0.1 d-1 in Leersia hexandra Swartz and Ludwigia peploides group, below 0.05 d-1 in Paspalum distichum L., Hydrocotyle vulgaris, Iris pseudacorus group. While the plants were proved to aggravate total nitrogen release by accumulating in sediment, with concentration in overlaying water below 0.4 mg·L-1 in Paspalum distichum and Iris pseudacorus L. group; with release rate below 0.02 mg·L-1. Root weight density, root length density, root surface area density were major factors, which increased the proportion of particles in sediment with diameter of below 50 µm, therefore decreased sediment resuspension against hydraulic disturbance; the root system also enriched total nitrogen in sediment and absorbed phosphorus from sediment. These five kinds of plants in terrestrial-aquatic transverse actually repressed nitrogen and phosphorus release from sediment in two ways mentioned above, Paspalum distichum L. and Iris pseudacorus L. possessed the best effect due to their developed root system, followed by Leersia hexandra Swartz and Hydrocotyle vulgaris, and Ludwigia peploides had the least effect.

[Modeling of Water Quality Response to Land-use Patterns in Taizi River Basin Based on Partial Least Squares].

Land use change in river basin is one of the most significant factors that influence river water quality. Based on remote sensing images and river water quality data of Taizi River Basin, partial least squares (PLS) model was applied to explore the relationship between water quality and land use patterns at sub-watershed scale. In this study, PLS model was established by using the percentage of area of land use patterns from seven different sub-watersheds as the variables and the concentrations of four water quality parameters as the observations. The established model was further tested with the data from other sub-watersheds in Taizi River Basin. The results indicated that total nitrogen (TN) and nitrate (NO3-) were significantly associated with land use types in Taizi River Basin with determination coefficient (R2) greater than 0.62. As for chloride (Cl-) and sulfate (SO42-), measured values and fitted values had a relatively low fitting precision (R2<0.5), which meant land use pattern was not the main factor affecting the concentrations of Cl-and SO42- in river water. Meanwhile, river water quality had a strong correlation with the percentage of area of unused land at the sub-basin scale (influence coefficient>0.24), although unused land area in the Taizi river basin was small.

Analysis of the relationship between economic growth and industrial pollution in Zaozhuang, China-based on the hypothesis of the environmental Kuznets curve.

In Zaozhuang, economic development affects the discharge amount of industrial wastewater, chemical oxygen demand (COD), and ammonia nitrogen (NH3-N). To reveal the trend of water environmental quality related to the economy in Zaozhuang, this paper simulated the relationships between industrial wastewater discharge, COD, NH3-N load, and gross domestic product (GDP) per capita for Zaozhuang (2002-2012) using environmental Kuznets curve (EKC) models. The results showed that the added value of industrial GDP, the per capita GDP, and wastewater emission had average annual growth rates of 16.62, 16.19, and 17.89 %, respectively, from 2002 to 2012, while COD and NH3-N emission in 2012, compared with 2002, showed average annual decreases of 10.70 and 31.12 %, respectively. The export of EKC models revealed that industrial wastewater discharge had a typical inverted-U-shaped relationship with per capita GDP. However, both COD and NH3-N showed the binding curve of the left side of the "U" curve and left side U-shaped curve. The economy in Zaozhuang had been at the "fast-growing" stage, with low environmental pollution according to the industrial pollution level. In recent years, Zaozhuang has abated these heavy-pollution industries emphatically, so pollutants have been greatly reduced. Thus, Zaozhuang industrial wastewater treatment has been quite effective, with water quality improved significantly. The EKC models provided scientific evidence for estimating industrial wastewater discharge, COD, and NH3-N load as well as their changeable trends for Zaozhuang from an economic perspective.

Unraveling the role of Arg4 and Arg6 in the auto-inhibition mechanism of GSK3ß from molecular dynamics simulation.

Glycogen synthase kinase 3ß (GSK3ß) is a multifunctional serine/threonine protein kinase that is involved in several biological processes including insulin and Wnt signaling pathways. GSK3ß can be phosphorylated by the protein kinase B (PKB). The mutations of Arg4 and Arg6 to alanine at N-terminal GSK3ß have been reported to impair its ability to autophosphorylate at Ser9. Despite the extensive experimental observations, the detailed mechanism for the auto-inhibition of GSK3ß has not been rationalized at the molecular level. In this study, we have demonstrated the structural consequences of GSK3ß R4A and R6A mutations and the atomic changes that influenced the loss of PKB-binding affinity. Molecular dynamics simulation results suggested significant loss in atomic contacts in the R4A and R6A mutant systems compared to the wild-type system. Furthermore, we observed many notable changes (such as conformation, residues motions, hydrogen bonds, and binding free energy) in the mutated GSK3ß-PKB complexes. Loss of binding affinity in the mutated systems rendered the decrease in GSK3ß phosphorylation, which, in turn, impaired the auto-inhibition of GSK3ß. The significant outcomes obtained from this study can explain the auto-inhibition of GSK3ß and maybe facilitate type 2 diabetes mellitus researches and in developing the potent drug therapies.