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Iris typhifolia Kitag is a perennial herbaceous species with high ornamental and applied value. Elucidating the mechanism of saline–alkali tolerance in Iris is crucial for their promotion in saline–alkali areas. Saline–alkali stress is one of the factors that affects plant growth, which has become a significant global issue. In this study, we measured the physiological and biochemical indexes of I. typhifolia, through germination and potting trials, to evaluate the resistance of I. typhifolia to different levels of artificial saline–alkali stress (0, 50, 100, 150, and 200 mmol·L−1). The results showed that artificial saline–alkali stress negatively impacted germination parameters, cell membrane integrity, and photosynthetic parameters. Different trends in osmoregulatory substances and endogenous hormones were observed. It was shown that I. typhifolia had a potential adaptability to the saline–alkali environment by enhancing its internal defense mechanism. Based on regression analyses, the germination threshold of I. typhifolia was calculated to be 87.15 mmol·L−1, which provided a theoretical basis for the application in soil saline–alkalization areas. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are becoming increasingly promising as environmentally friendly solvents, and accurate prediction of their density and viscosity is crucial for their successful industrial application. However, existing density and viscosity prediction models primarily rely on temperature variations and often overlook changes in the molar ratio of hydrogen bond acceptors (HBA) to hydrogen bond donors (HBD) in DESs, limiting their practicality. Therefore, in this study, several binary and ternary DESs were synthesized using choline chloride (ChCl) as the hydrogen bond donor. The densities and viscosities of these DESs were measured, and prediction models for the density and viscosity of DESs based on temperature and molar ratio were developed. These models were used to forecast the density and viscosity of DESs at different temperatures and molar ratios. The model parameters are calibrated using experimental data from this research. Finally, the model is utilized to predict the density and viscosity of DESs mentioned in this paper, as well as DESs with varying HBAs and HBDs. The results demonstrate that the discrepancy between the literature value, experimental value, and calculated value is less than 6%, confirming the universal applicability and reliability of the prediction model proposed in this study. [ABSTRACT FROM AUTHOR]

Abstract Background Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Rectal locations are very rare, and minimally invasive surgery is a good choice for the treatment of rectal GISTs. Case presentation Two women each had a mass located on the lower vaginal-rectal space as determined by transvaginal ultrasound (TV-US), pelvis MR imaging, and colonoscopy. The patients successfully underwent transvaginal excision. The spindle-shaped cells were found in pathological test. The immunohistochemical analysis showed that CD117 and Dog-1 were stained positively. These results confirmed the masses as GISTs. The postoperative period was uneventful without anal dysfunction. Two patients were received adjuvant treatment with imatinib after surgery. Conclusion Transvaginal excision could be a minimally invasive and safe alternative treatment in the management of rectal GISTs in lower locations.

In this study, we employ first-principles calculations to explore the electronic and valleytronic properties of single-layer (SL) SMSiN2 (M = Mo, W), which are two-dimensional Janus materials with strong spin–orbit coupling. Our findings indicate that SL SMoSiN2/SWSiN2 possess a direct/indirect band gap, where the valence band maximum is situated at the K/K′ point, giving rise to the formation of degenerate valleys. When considering spin–orbit coupling, SMoSiN2 and SWSiN2 demonstrate intriguing valley spin splitting in their valleys, with a maximum splitting of up to 0.14/0.39 eV in the valence bands. By implementing magnetic doping with V and Cr, we provide a demonstration that valley polarization could be realized in SL SMSiN2. Moreover, the findings reveal high carrier mobility in SL SMSiN2, notably in SWSiN2, where hole carriers can achieve a remarkable mobility of up to 7.98 × 103 cm2 V−1 s−1 along the zigzag direction. Furthermore, our observations suggest that strain can be effectively utilized to manipulate the character and magnitude of the band gap, as well as the valley spin splitting in these materials. [ABSTRACT FROM AUTHOR]

Bioplastic bags mixed with food waste seem inevitable with the growth of waste classification and the banning of non-biodegradable polymers in China. To solve the asynchronous degradation of both food waste (FW) and bioplastics in the anaerobic digestion process, we investigated to determine the most effective pretreatment method. Among the three treatment options—physical, chemical, and biological—we found that biological pretreatment holds the most promise, primarily due to the efficient catalytic hydrolysis capacity of enzymes. We utilized three types of enzymes—amylases, lipases, and proteinase K—at a concentration of 0.075 g L−1 for pretreatment. The pretreatment process involved subjecting the FW/bioplastics mixture to enzymatic action for a duration of 48 h, at temperatures of 35 °C and 55 °C. We observed that the methane production from anaerobic digestion increased by 22.72%, 32.51%, and 60.95%, respectively, at the temperature of 55 °C when treated with the mentioned enzymes. Additionally, the degradation time of the bioplastic bags decreased from 30 to 24 days. Scanning electron microscopy (SEM) analysis revealed noticeable physical degradation, with the emergence of holes on the surface of the bioplastic following the enzymatic pretreatments and the effect of proteinase K was the most obvious. Further analysis using Fourier-transform infrared spectroscopy (FTIR) indicated that the peak observed at 1700 cm−1 is a characteristic peak of proteinase K depolymerization and the peak sign was significantly weakened after the experiment. This discovery suggests that proteinase K possesses a unique ability to break certain chemical bonds within bioplastics. Furthermore, novel bacterial species were identified in the substrate microbiome after proteinase K pretreatment. Notably, temperature was also a significant factor influencing material degradation. The enzymatic pretreatment enhanced biodegradation, resulting in enhanced methane yield during anaerobic digestion. These findings demonstrated the efficacy of biological pretreatment in effectively addressing the asynchronous degradation issue between food waste and bioplastics. [ABSTRACT FROM AUTHOR]

Simple Summary: Ribosomes are macromolecular complexes responsible for mRNA translation. When ribosome biogenesis is hyperactive or aberrant or ribosomal factors are mutated, ribosomopathies may occur, elevating cancer risks. This review aims to discuss recent research regarding the complex mechanism responsible for regulating ribosome biogenesis and delineate how the deregulation of this process is connected to cancer pathogenesis. Providing our perspective on how these observations provide opportunities for designing new targeted cancer treatments. In doing so, we hope to draw attention to persisting gaps in the literature and candidate targets involved in ribosomal biogenesis for cancer therapies to facilitate further research in this field. Ribosomes are macromolecular ribonucleoprotein complexes assembled from RNA and proteins. Functional ribosomes arise from the nucleolus, require ribosomal RNA processing and the coordinated assembly of ribosomal proteins (RPs), and are frequently hyperactivated to support the requirement for protein synthesis during the self-biosynthetic and metabolic activities of cancer cells. Studies have provided relevant information on targeted anticancer molecules involved in ribosome biogenesis (RiBi), as increased RiBi is characteristic of many types of cancer. The association between unlimited cell proliferation and alterations in specific steps of RiBi has been highlighted as a possible critical driver of tumorigenesis and metastasis. Thus, alterations in numerous regulators and actors involved in RiBi, particularly in cancer, significantly affect the rate and quality of protein synthesis and, ultimately, the transcriptome to generate the associated proteome. Alterations in RiBi in cancer cells activate nucleolar stress response-related pathways that play important roles in cancer-targeted interventions and immunotherapies. In this review, we focus on the association between alterations in RiBi and cancer. Emphasis is placed on RiBi deregulation and its secondary consequences, including changes in protein synthesis, loss of RPs, adaptive transcription and translation, nucleolar stress regulation, metabolic changes, and the impaired ribosome biogenesis checkpoint. [ABSTRACT FROM AUTHOR]

The contamination of urban rivers substantially threatens urban ecology, public health, and general progress. Addressing this matter is complex and challenging, particularly in tidal rivers. After investigating the climate conditions, population, and distribution of rivers and pollution in Sanya, China, a hydraulic and water quality model was built for Sanya utilizing InfoWorks ICM, and a comprehensive remediation approach was proposed. The implementation of this scheme led to a substantial decrease in point and non-point sources of pollution. In particular, COD, NH3-N, and TP were reduced by 87.00%, 84.01%, and 74.24%, respectively, from point source pollution. Point source pollution was well-managed north of the bridge, with a reduction rate close to 40% for non-point source pollution. This research confirmed that pollutants are only temporarily retained in the river at high tide and are discharged as the tide recedes, thus having a limited impact on long-term pollution discharge. This research provides valuable references for applying water environment models and the comprehensive treatment of tidal river pollution. The final plan scheme is to significantly improve the water quality of Sanya's rivers by effectively controlling the discharge of pollutants while achieving considerable cost savings of approximately CNY 1.7 billion. [ABSTRACT FROM AUTHOR]

To substitute fossil resources, it is necessary to investigate the conversion of biomass into 1,2-propanediol (1,2-PDO) as a high-value-added chemical. The Pt/deAl-Beta@Mg(OH)2 catalytic system is designed to obtain a higher 1,2-PDO production yield. The optimal yield of 1,2-PDO is 34.1%. The unique shell-core structure of the catalyst demonstrates stability, with a catalytic yield of over 30% after three times of use. The primary process path from glucose to 1,2-PDO, glucose-hexitol-1,2-PDO, is speculated by the experiments of intermediate product selectivity. The alkaline catalytic mechanism of the reaction process is elucidated by studying catalyst characterization and analyzing different time courses of products. The introduction of Mg(OH)2 improves the target yield by promoting the isomerization from glucose to fructose and retro-aldol condensation (RAC) conversion, with pseudo-yield increases of 76.1% and 42.1%, respectively. By studying the processes of producing lactic acid and 1,2-PDO from glucose, the glucose hydrogenolysis flow chart is improved, which is of great significance for accurately controlling 1,2-PDO production in industrial applications. The metal, acid, and alkali synergistic catalytic system constructed in this paper can provide a theoretical basis and route reference for applying biomass conversion technology in practice. [ABSTRACT FROM AUTHOR]

Abstract Background The p21 codon 31 single nucleotide polymorphism (SNP), rs1801270, has been linked to cervical cancer but with controversial results. The aims of this study were to investigate the role of p21 SNP-rs1801270 and other untested p21 SNPs in the risk of cervical cancer in a Chinese population. Methods We genotyped five p21 SNPs (rs762623, rs2395655, rs1801270, rs3176352, and rs1059234) using peripheral blood DNA from 393 cervical cancer patients and 434 controls. Results The frequency of the rs1801270 A allele in patients (0.421) was significantly lower than that in controls (0.494, p = 0.003). The frequency of the rs3176352 C allele in cases (0.319) was significantly lower than that in controls (0.417, p < 0.001).The allele frequency of other three p21 SNPs showed not statistically significantly different between patients and controls. The rs1801270 AA genotype was associated with a decreased risk for the development of cervical cancer (OR = 0.583, 95%CI: 0.399 - 0.853, P = 0.005). We observed that the three p21 SNPs (rs1801270, rs3176352, and rs1059234) was in linkage disequilibrium (LD) and thus haplotype analysis was performed. The AGT haplotype (which includes the rs1801270A allele) was the most frequent haplotype among all subjects, and both homozygosity and heterozygosity for the AGT haplotype provided a protective effect from development of cervical cancer. Conclusions We show an association between the p21 SNP rs1801270A allele and a decreased risk for cervical cancer in a population of Chinese women. The AGT haplotype formed by three p21 SNPs in LD (rs1801270, rs3176352 and rs1059234) also provided a protective effect in development of cervical cancer in this population.

Abstract Background Studies have shown that type-specific persistence of high-risk human papillomavirus (HPV) infection contributed significantly to cervical carcinogenesis. Methods In this population-based study (on 24041 women), we report on the prevalent genotypes of HPVs and the prevalent genotypes of HPV persistent infection in the northeast of China. Results Our results showed that in HPV infected women (45.6% in total), (95% CI, 44.97%–46.23%), 17.35% (95%CI, 16.87%–17.83%) suffered persistent infection. The most common high-risk HPV types in persistent positivity were HPV-16 (18.21%; 95%CI, 17.04%–19.38%), HPV-58 (13.2%; 95%CI, 12.17%–14.23%), HPV-18 (8.66%; 95%CI, 7.81%–9.51%), HPV-52 (7.06%; 95% CI, 6.28%–7.84%) and HPV-33 (6.78%; 95% CI, 6.02%–7.54%). The prevalence of persistent infections with HPV-16,–58, −18, −52 and 33 in cervicitis were lower compared to those in CIN (all P Conclusions we provided extensive results of HPV genotype prevalence and distribution in the northeast of China. HPV genotyping is worthwhile to perform because of its independent prognostic value in cervical cancer

Introduction and Hypothesis: Perivascular epithelioid cell neoplasms (PEComas) are rare mesenchymal tumors that originate from perivascular epithelioid cells. The uterus is the second most common organ to be affected by PEComa. Most PEComas are benign and the prognosis is usually good. Surgery is the main treatment at present, and adjuvant therapy is mainly used for malignant cases. However, because of the lack of described cases, the best diagnosis and treatment of these tumors cannot be determined. Methods: From 2009 to 2020, 13 patients from Shengjing Hospital (China Medical University), with uterine PEComa, who met the inclusion criteria and appropriate pathological diagnosis were enrolled in this study. Clinical, pathological, and therapeutic features were retrospectively analyzed to determine the best approach towards diagnosis and treatment. Results: All the enrolled patients underwent surgical treatment; four of them had a malignant PEComa. Three of the malignant patients received chemotherapy after surgery; among them, one died, another showed no obvious recurrence after regular re-examination, and the third did not undergo any further treatment despite short-term recurrence. However, upon regular re-examination, no progress was observed. The fourth malignant patient did not receive chemotherapy after surgery and showed no obvious recurrence during regular reviews. Conclusion: The preoperative diagnosis of uterine PEComa lacks specificity and therefore is often confused with uterine leiomyoma or leiomyosarcoma. We conclude that uterine PEComa can be diagnosed by combined analysis of immunohistochemistry and post-operative pathology. Though surgical resection is still the main treatment, high-risk patients can be given adjuvant treatment to strengthen disease control. [ABSTRACT FROM AUTHOR]

Hydrogen generation based on photocatalytic water splitting is a promising strategy for renewable energy production. Significant efforts have been made to improve the photocatalytic efficiency. However, the light harvesting ability of photocatalytic systems in the visible region still needs to be significantly improved to enable them to be a competitive technology for hydrogen generation. Herein, for the first time, we synthesized 2D Zn–Ag–In–S (ZAIS) nanosheets with strong absorption in the visible region and applied them for photocatalytic hydrogen generation. The exploration of oxygen passivation (O-ZAIS) reduced the defect concentration and nonradiative decay. The hydrogen generation rate is up to 25.2 mmol g−1 h−1, which is 14.7 times higher than that of pristine ZAIS nanosheets. Furthermore, by introducing 2D Co3O4 as the co-catalyst, carrier separation is accelerated, giving rise to a hydrogen generation efficiency of 43.6 mmol g−1 h−1. To the best of our knowledge, this is the highest efficiency reported among all kinds of 2D photocatalysts. [ABSTRACT FROM AUTHOR]

Background: Dickkopf-4 (DKK4), a member of DKK family, appears to be a divergent protein. It remained multi-biological functions in carcinogenesis. The effect of DKK4 on the ovarian cancer cells remains unclear. This study detected the clinical significance of DKK4 in epithelial ovarian cancer (EOC) patients and its role in invasion.Methods: QRT-PCR and western blot analysis were used to examine the levels of DKK4 mRNA and protein in 33 EOC tissues and 33 benign ovarian tumors. Immunohistochemical analysis was performed to assess DKK4 expression in 239 EOC samples. siRNA-mediated DKK4 silence was conducted. Transwell assay was used to detect the invasive ability. Phalloidin was used to stain the formations of actin filaments.Results: The expressions of DKK4 mRNA and protein were elevated in EOC tissues as compared with those in benign ovarian tumors (p = 0.001 and <0.0001 respectively). Immunohistochemical results showed the strong expression of DKK4 protein was positively associated with late FIGO stage (p = 0.005) and poor disease free survival in univariate and multivariate analysis (p < 0.0001 and p = 0.001, respectively). SiRNA-mediated DKK4 knockdown inhibited cell invasive ability (all p < 0.0001) and the formations of actin filaments. DKK4 could promote the phosphration of c-JUN and JNK (p < 0.0001 and p = 0.001, respectively).Conclusions: Our results indicated that DKK4 might be contributed to predicting EOC progression and prognosis. DKK4 could promote the invasion of EOC through JNK activation. [ABSTRACT FROM AUTHOR]

SrCoO 3− δ is a mixed ionic-electronic conductor with multiphase. The structural instability, chemical and thermal incompatibility with the standard electrolytes in this material restrict its widespread applications as electrochemical devices. Here we report the characterization and performance improvement of SrCo 0.8 Fe 0.1 Nb 0.1 O 3− δ (SCFN) perovskite as a potential cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The SCFN material exhibits good chemical compatibility with both La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3− δ (LSGM) and Gd 0.1 Ce 0.9 O 1.95 (GDC) electrolytes at 950 °C for 10 h. Fe and Nb co-doping significantly improves the structural stability, thermal expansion compatibility, and electrochemical performance of the SCFN material as compared to the undoped SrCoO 3− δ and Fe-doped SrCo 0.8 Fe 0.2 O 3− δ (SCF). The introduction of GDC further improves the thermal compatibility and electrochemical performance of the SCFN–GDC composite cathodes, where the thermal expansion coefficients decrease from 24.5 × 10 −6 K −1 for SCFN to 16.8 × 10 −6 K −1 for SCFN–50GDC between 30 and 950 °C in air, the corresponding area specific resistances are 0.091 and 0.075 Ω cm 2 at 700 °C, respectively. The SCFN and its composites reveal some promising aspects of applications in IT-SOFCs. The SCFN–GDC composites provide a trade-off between TEC and electrochemical performance for application as IT-SOFC cathode materials. [ABSTRACT FROM AUTHOR]

The Rab GTPase family protein Rab14 has been implicated in cancer development. However, its clinical significance in ovarian cancers and its biological effects have not been examined. The present study aims to examine the clinical significance, biological roles, and molecular mechanism of Rab14 in ovarian cancer progression. We examined expression pattern of Rab14 in 122 cases of ovarian cancer specimens using immunohistochemistry and found Rab14 overexpression correlated with FIGO stage ( p = 0.0041). We depleted Rab14 in SKOV3 cells using siRNA and overexpressed Rab14 in SW626 cells. Knockdown of Rab14 inhibited cell growth and invasion while its overexpression facilitated cell growth and invasion. In addition, Rab14 overexpression increased paclitaxel resistance in SW626 cells while its depletion reduced drug resistance. Then, we investigated the role of Rab14 in the regulation of WNT/β-catenin signaling, demonstrating Rab14 overexpression regulated GSK3β phosphorylation and nuclear β-catenin accumulation. Rab14 depletion inhibited while its overexpression enhanced TCF transcriptional activity with corresponding change of Wnt target genes including MMP7 and c-myc. Wnt inhibitor abolished the effect of Rab14 on cell proliferation and Wnt target genes. In conclusion, the present study demonstrated that Rab14 promotes aggressiveness of ovarian cancer cell through, at least partly, Wnt signaling pathway. [ABSTRACT FROM AUTHOR]

Wnt-11 is a positive regulator of the Wnt signaling pathway, which plays a crucial role in carcinogenesis. However, Wnt-11 expression in cervical cancer has not been well investigated. The aim of this study was to investigate the role of Wnt-11 in cervical tumor proliferation and invasion. This study examined 24 normal cervical squamous epithelia, 29 cervical intraepithelial neoplasia (CIN), and 78 cervical cancer samples. The expression of Wnt-11 was investigated by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction analysis. The expression of the high-risk human papilloma virus (HR-HPV) E6 oncoprotein was also investigated by immunohistochemistry. In addition, the expression of Wnt-11, HR-HPV E6, JNK-1, phosphorylated JNK-1( P-JNK1), and β-catenin was examined by western blot analysis following Wnt-11 knockdown or overexpression in HeLa or SiHa cells, respectively. The promotion of cervical cancer cell proliferation and invasion was investigated using the cell counting kit-8 and Matrigel invasion assay, respectively. Wnt-11 and HR-HPV E6 expression increased in a manner that corresponded with the progression of cervical cancer and was significantly correlated with the International Federation of Gynecology and Obstetrics cancer stage, lymph node metastasis, tumor size, and HPV infection. Wnt-11 protein expression was positively associated with HR-HPV E6 protein expression in all 78 cervical cancer samples ( P < 0.001). Furthermore, Wnt-11 was positively associated with P-JNK1 expression and promoted cervical cancer cell proliferation and invasion. These observations suggest that the increased Wnt-11 expression observed in cervical cancer cells may lead to the phosphorylation and activation of JNK-1 and significantly promote tumor cell proliferation and cell migration/invasion through activation of the Wnt/JNK pathway. Consequently, Wnt-11 may serve as a novel target for cervical cancer therapy. [ABSTRACT FROM AUTHOR]

Lignin is a renewable biomass resource with excellent application potential; however, the extremely complex structure of lignin renders it difficult to effectively degrade and use. In this context, it is necessary to identify a catalyst that can be easily recovered to increase the lignin degradation rate. In this paper, two temperature-responsive deep eutectic solvents (TRDESs), which can form homogeneous phases with reactants at a high temperature and separate from the reaction system at low temperature, were designed to catalyse lignin degradation. Based on the |HOMO-LUMO| gap, [Bmim]Cl and ChCl, which have a high catalytic activity, were selected from 22 deep eutectic solvents (DESs). [Bmim]Cl-EDTA (mole ratio = 1:1) was obtained by combining [Bmim]Cl and EDTA. ChCl-SA (mole ratio = 1:1) was obtained by combining ChCl and salicylic acid (SA). Results of COSMO-SAC modelling calculations and solubility experiments indicated that TRDESs can respond to temperature. Specifically, these solvents can form a homogeneous phase with the reactants at high temperatures, thereby increasing the number and uniformity of the reaction sites. Moreover, the solvents can be separated from the reaction system at low temperature, which enables efficient recycling of the catalyst. Results of lignin degradation experiments indicated that the catalytic performance of [Bmim]Cl-EDTA is higher than that of the other DESs: the degradation rate of lignin is 83.63%, and the catalyst exhibits a satisfactory catalytic effect even after multiple cycles. • A molecular design method of temperature-responsive DES is proposed. • Two TRDESs with temperature response are designed. • The two TRDESs solve the problem that the catalyst is not easy to recover. • Two TRDESs can improve the degradation efficiency of lignin. • The reliability of molecular design is proved by experiments. [ABSTRACT FROM AUTHOR]

Dickkopf-1 (DKK-1) is a secreted protein involved in embryonic development. Dickkopf-1 is also implicated in osteoporosis, arthritis, and cancer and represents a potential therapeutic target for the treatment of these diseases. Because DKK-1 encodes a secreted protein, we investigated whether the DKK-1 protein is secreted into the sera of patients with gynecological cancer. The levels of DKK-1 protein were assessed by enzyme-linked immunosorbent assay in the sera of 104 patients with gynecological cancer including 36 with ovarian, 40 with cervical, and 28 with endometrial cancers. The serum levels of DKK-1 protein were higher in patients with cervical (314.13 [385.02] pg/mL, P = 0.000) and endometrial (46.95 [21.62] pg/mL, P = 0.000) cancers than in healthy individuals (29.45 [11.86] pg/mL). The serum levels of DKK-1 protein were associated with clinical stage in all patients with gynecological cancer. In patients with cervical cancer, the serum levels of DKK-1 protein were also associated with histological type and lymphatic metastasis. Dickkopf-1 protein detection using enzyme-linked immunosorbent assay as a molecular marker can contribute to the detection and the diagnosis of cervical and endometrial cancers, especially for cervical squamous cell cancer. [ABSTRACT FROM AUTHOR]

Highlights • A caffeic acid O -methyltransferase was engineered by rational design to improve its catalytic efficiency to produce melatonin. • The At COMT activity was improved by 9.5-fold by strengthening the interactions between binding-pocket and NAS terminal structure. • The strategies include the introduction of N H⋯π interaction, hydrophobic interaction and elimination of electrostatic repulsion. • This work provides hints for O -methyltransferase engineering and lays foundation for biotechnological production of melatonin. Abstract O -Methylation of N -acetylserotonin (NAS) has been identified as the bottleneck in melatonin biosynthesis pathway. In the present paper, caffeic acid O -methyltransferase from Arabidopsis thaliana (AtCOMT) was engineered by rational design to improve its catalytic efficiency in conversion of NAS to melatonin. Based on the notable difference in the terminal structure of caffeic acid and NAS, mutants were designed to strengthen the interactions between the substrate binding pocket of the enzyme and the terminal structure of the unnatural substrate NAS. The final triple mutant (C296F-Q310L-V314T) showed 9.5-fold activity improvement in O -methylation of NAS. Molecular dynamics simulations and binding free energy analysis attributed the increased activity to the higher affinity between the substrate terminal structure and AtCOMT, resulting from the introduction of N H⋯π interaction by Phe296 substitution, hydrophobic interaction by Thr314 substitution and elimination of electrostatic repulsion by substitution of Gln310 with Leu310. This work provides hints for O -methyltransferase engineering and meanwhile lays foundation for biotechnological production of melatonin. [ABSTRACT FROM AUTHOR]