Molecular Modification Research Articles

Effect of transglutaminase crosslinking on the structural, physicochemical, functional, and emulsion stabilization properties of three types of gelatins

Molecular modification has attracted many attentions in the field of gelatin science. In this work, a transglutaminase (TG) modification method was developed and applied to modify bovine bone gelatin, porcine skin gelatin, and cold-water fish skin gelatin, and then the effect of TG crosslinking on the structural, physicochemical, functional, and emulsion stabilization properties of three types of gelatins were explored and compared. The results demonstrated that TG modification increased the nanoparticle formation behaviors and change the physicochemical and functional properties of three types of gelatins. Further, TG-modified aquatic gelatin showed comparable foaming properties (147% ± 6% for foaming capability and 55% ± 4% for foam stability) and higher emulsifying properties (18 ± 1 m2/g for emulsion activity index and 142 ± 11 min for emulsion stability index) to unmodified mammalian gelatins. In addition, TG-modified gelatins decreased the droplet sizes and increased creaming stability of fish oil-loaded emulsions compared with unmodified gelatins. All these results suggested TG modification was an efficient molecular modification method for gelatins. Moreover, TG-modified aquatic gelatin could be potential mammalian gelatin replacer. This work could provide useful information to understand the relationship among animal sources, tissue sources, extraction methods, amino acid compositions, molecular modification, molecular structure, physicochemical properties, functional properties, and emulsification stability of gelatins.

Research progress of anthocyanin prebiotic activity: A review

BackgroundAnthocyanins are a kind of flavonoids and natural water-soluble pigments, which endow fruits, vegetables, and plants with multiple colors. They are important source of new products with prebiotic activity. However, there is no systematic review documenting prebiotic activity of anthocyanins and their structural analogues. This study aims to fill this gap in literature. PurposeThe objective of this review is to summarize and evaluate the prebiotic activity of anthocyanin's, and discuss the physical and molecular modification methods to improve their biological activities. Study design and methodsIn this review, the databases (PubMed, Google Scholar, Web of Science, Researchgate and Elsevier) were searched profoundly with keywords (anthocyanin's, prebiotics, probiotics, physical embedding and molecular modification). ResultsA total of 34 articles were considered for reviewing. These studies approved that anthocyanins play an important role in promoting the proliferation of probiotics, inhibiting the growth of harmful bacteria and improving the intestinal environment. In addition, physical embedding and molecular modification have also been proved to be effective methods to improve the prebiotic activity of anthocyanins. Anthocyanins could promote the production of short chain fatty acids, accelerate self degradation and improve microbial related enzyme activities to promote the proliferation of probiotics. They inhibited the growth of harmful bacteria by inhibiting the expression of harmful bacteria genes, interfering with the role of metabolism related enzymes and affecting respiratory metabolism. They promoted the formation of a complete intestinal barrier and regulated the intestinal environment to keep the body healthy. Physical embedding, including microencapsulation and colloidal embedding, greatly improved the stability of anthocyanins. On the other hand, molecular modification, especially enzymatic modification, significantly improved the biological activities (antioxidant, prebiotic activity and so on) of anthocyanins. ConclusionAll these research results displayed by this review indicate that anthocyanins are a useful tool for developing prebiotic products. The better activities of the new anthocyanins formed by embedding and modification may make them become more effective raw materials. Our review provides a scientific basis for the future research and application of anthocyanins.

Post-Translational Modifications of STING: A Potential Therapeutic Target

Stimulator of interferon genes (STING) is an endoplasmic-reticulum resident protein, playing essential roles in immune responses against microbial infections. However, over-activation of STING is accompanied by excessive inflammation and results in various diseases, including autoinflammatory diseases and cancers. Therefore, precise regulation of STING activities is critical for adequate immune protection while limiting abnormal tissue damage. Numerous mechanisms regulate STING to maintain homeostasis, including protein-protein interaction and molecular modification. Among these, post-translational modifications (PTMs) are key to accurately orchestrating the activation and degradation of STING by temporarily changing the structure of STING. In this review, we focus on the emerging roles of PTMs that regulate activation and inhibition of STING, and provide insights into the roles of the PTMs of STING in disease pathogenesis and as potential targeted therapy.

Molecular modification of Bacillus stearothermophilus NO2 cyclodextrin glucosyltransferase and preparation of α-cyclodextrin

Cyclodextrin (CD) is produced by the catalysis of starch or starch derivatives by cyclodextrin glucosyltransferase (CGTase), and its yield is mainly limited by the product and reaction specificity of CGTase. In this study, we use CGTase derived from Bacillus stearothermophilus NO2, exhibiting high expression levels and good stability for molecular modification. The N353A mutant effectively decreases the hydrolysis activity, and the ratio of the kcat values (cyclization to hydrolysis activity) is 86.46, which is threefold that of the wild type. The E142P mutant effectively enhances α-CD specificity, which increases the ratio of kcat values (α-CD to β-CD formation) from 2.18 of the wild-type to 2.42. The N353A/E142P mutant weakens the hydrolysis side reaction and enhances α-CD specificity, and the proportion of α-CD products is 53.67%, which is 15.62% higher than that of the wild-type. This research focuses on CGTase reaction and product specificities, which suggest a novel method for the industrial production of α-CD.

Tuning lignin properties by mild ionic-liquid-mediated selective alcohol incorporation

The synthesis of ideal, well-defined, functionalized lignins is of great significance for realizing the full valorization potential of lignocellulosic biomass. Here, the application of acidified triethylammonium triflate is reported, allowing for the selective benzylic alkoxylation of different lignins at room temperature. Full benzylic alkoxylation of typically hard-to-process, high-molecular-weight lignin was achieved in this medium by simple mixing with different alcohols. Limited lignin degradation was observed, and lignin modification was also achieved within the lignocellulosic matrix. This allows the method to be used as a biomass pretreatment, which was shown to also enhance enzymatic saccharification. The reactivity, stability, and hydrophobicity of the lignin can be tuned based on the alcohol used. Effective recovery of the ionic liquid and recycling of the ionic liquid was achieved. Thus, a straightforward mild method is demonstrated to introduce new functionality in lignin, allowing it to be tuned towards novel applications. • Benzylic alkoxylation of different lignins was achieved at room temperature • An effective ionic liquid consisted of triethylamine with excess triflate acid • Key factors that influence high molecular lignin modification are proposed • Lignin with tunable properties was achieved in a recyclable reaction medium Inedible agricultural residues are a promising source of renewable carbon. Biopolymers retained in such inedible biomass can serve as sustainable replacements to fossil-based polymeric products. Lignin is a major component of lignocellulosic (inedible) biomass that is currently underutilized due to its complex structure and high reactivity. During separation from other biomass components, lignin is typically heavily degraded and condensed, making the product difficult to process and use for higher value applications. The native highly functionalized structure of lignin makes it a potent biopolymer substrate for complex material applications. Thus, acquisition of lignin with relatively defined structure and properties provides the prospects of high-value use. One key aspect for processability of lignin is that it can be blended with other polymers, and thus tuning its hydrophobic and hydrophilic properties while leaving the main polymeric structure intact is potentially of great importance. A recyclable acidified ionic liquid mixed with different alcohols can achieve benzylic alkoxylation of lignin obtained from different isolation methods and biomass sources at room temperature. Lignins modified from this process are endowed with tunable properties. Solvation state of lignin in this reaction medium plays an important role to achieve a high degree of alkoxylation of lignin.

Nanoscale Encapsulation of Hybrid Perovskites Using Hybrid Atomic Layer Deposition.

Organic-inorganic hybrid perovskites have shown tremendous potential for optoelectronic applications. Ion migration within the crystal and across heterointerfaces, however, imposed severe problems with material degradation and performance loss in devices. Encapsulating hybrid perovskite with a thin physical barrier can be essential for suppressing the undesirable interfacial reactions without inhibiting the desirable transport of charge carriers. Here, we demonstrated that nanoscale, pinhole-free Al2O3 layer can be coated directly on the perovskite CH3NH3PbI3 using atomic layer deposition (ALD). The success can be attributed to a multitude of strategies including surface molecular modification and hybrid ALD processing combining the thermal and plasma-enhanced modes. The Al2O3 films provided remarkable protection to the underlying perovskite films, surviving by hours in solvents without noticeable decays in either structural or optical properties. The results advanced the understanding of applying ALD directly on hybrid perovskite and provided new opportunities to implement stable and high-performance devices based on the perovskites.

Preparation and identification of an anti-nicarbazin monoclonal antibody and its application in the agriculture and food industries.

BackgroundAs a broad-spectrum drug against chicken coccidiosis, nicarbazine is widely used. The international community has made regulations and requirements on the residue limits of nicarbazine metabolites in chicken. The research reports on the detection methods of nicarbazine residues are mainly based on large-scale instruments such as high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry-mass spectrometry (LC/MS/MS) and so on. However, in the practical monitoring and detection application, the rapid, sensitive, efficient and accurate detection of nicarbazine residues is becoming more and more urgent.MethodsThis study aimed to establish an enzyme-linked immunosorbent assay (ELISA)-based method to detect nicarbazin drug residues with high sensitivity and specificity, and wide applicability. Artificial immunogens were prepared by molecular modification synthesis. Nuclear magnetic resonance (NMR) and ultraviolet analyses were conducted to confirm that the correct product was obtained. Monoclonal antibodies were acquired by immunizing mice and preparing hybridoma cells.ResultsIn this study, 4,4'-dinitrocarbanilide (DNC), a metabolite of nicarbazine, was synthesized and modified to make it have immunogenicity. Fifteen healthy female mice of 6–8 weeks old were immunized in three groups. The successfully immunized mice were screened by serum titer. One mouse with the highest titer was fused and cloned three times, and four positive cell lines were obtained. Nine monoclonal antibodies were obtained from mouse ascites. The best matched antigens and antibodies were screened by an ELISA chessboard method. A detection method of nicarbazine ELISA kit was developed. Our prepared anti-nicarbazin monoclonal antibody had a half-maximal inhibitory concentration (IC50) of 0.825 ng/mL, and the curve range was 0.3–24.3 ng/mL. There was no cross reaction to other six common anti-coccidiosis drugs. The recovery results showed that the fortified recovery of the chicken and duck samples ranged from 74.4–111.7%, the test results of which all met the requirements for veterinary drug residue detection.ConclusionsThis method, which uses a specific antibody against the nicarbazin metabolic product DNC, enables rapid quantitative detection. Our new ELISA-based method should facilitate the development of assays to monitor and detect agricultural and veterinary drug residues.

Genome wide association study identifies candidate genes related to fatty acid components in upland cotton (Gossypium hirsutum L.)

As an important source of edible vegetable oil, cottonseed oil and its fatty acid composition that determines its nutritional value have attracted growing attention in recent years. For the identification of the quantitative trait loci (QTLs) underpinning cottonseed oil content and fatty acid components, 83 representative upland cotton accessions grown in multiple environments were used in a genome-wide association study (GWAS) base on a CottonSNP63K array. Two, 8, 35, 26, 1, 3, 7 and 50 QTLs were identified for myristicoleic acid, palmitic acid, palmitoleic acid, oleic acid, linoleic acid, linolenic acid, total fatty acids and oil content, respectively. Four stable QTLs related to oleic acid accumulation, including qOA-D11-1, qOA-A05-2, qOA-D01-1, and qOA-D07-4, were identified. The candidate genes for these QTLs were further suggested as Gh_D11G0990, Gh_A05G2242, Gh_D01G2016 and Gh_D07G1914, respectively, based on haplotype block analysis and strong and direct linkage disequilibrium between significant SNPs and the genes. The ectopic expression of Gh_D01G2016 in yeast resulted in reductions in oil content and oleic acid content by 18.1% and 9.91%, respectively. The identification of Gh_D01G2016 as a candidate gene in regulating oil synthesis not only facilitates the understanding of the intricate mechanism underpinning the cottonseed oil biosynthesis, but also provide a potentially useful tool for molecular breeding and genetic modification of cottonseed oil.

Zwitterionic Modification of Polyethyleneimine for Efficient In Vitro siRNA Delivery.

Polyethylenimine (PEI) has been widely used in gene delivery. However, its high cytotoxicity and undesired non-specific protein adsorption hinder the overall delivery efficacy and the practical applications of PEI-based gene delivery systems. In this study, we prepared hydrophobically modified PEIs (H-PEIs) via the reaction of octanal with 40% of primary amines in PEI25k and PEI10k, respectively. Two common zwitterionic molecules, 1,3-propanesultone and β-propiolactone, were then used for the modification of the resulting H-PEIs to construct polycationic gene carriers with zwitterionic properties (H-zPEIs). The siRNA delivery efficiency and cytotoxicity of these materials were evaluated in Hela-Luc and A549-Luc cell lines. Compared with their respective parental H-PEIs, different degrees of zwitterionic modification showed different effects in reducing cytotoxicity and delivery efficiency. All zwitterion-modified PEIs showed excellent siRNA binding capacity, reduced nonspecific protein adsorption, and enhanced stability upon nuclease degradation. It is concluded that zwitterionic molecular modification is an effective method to construct efficient vectors by preventing undesired interactions between polycationic carriers and biomacromolecules. It may offer insights into the modification of other cationic carriers of nucleic acid drugs.

Dual Responsive Molecular-Arm Modified Single Enzyme Molecules for Efficient Cellulose Hydrolysis.

Immobilizing cellulase for improving its hydrolysis activity and recyclability is critical for a cost-effective and environment-friendly conversion of cellulosic biomass. However, developing a strategy for achieving a high mass-transfer rate and good separation efficiency between an insoluble cellulose substrate and cellulase remains difficult. Instead of the traditional method, a single-enzyme molecular modification method is used in this study. To modify cellulase and provide it with a temperature-pH dual responsive property, systemized poly(acrylic-acrylonitrile) (PAA-PAN) molecular arms are used. The modified cellulase can reversibly transform between liquid and solid phases. In the liquid phase, the modified cellulase can adjust its active center, increasing its hydrolysis efficiency and separation efficiency. Cellulase and glucose products can be easily separated in the solid phase, allowing the reuse of cellulase. The results show that the modified cellulase's hydrolysis efficiency is comparable to that of free cellulase and that the modified enzyme preserves more than 60% of its initial activity after 15 batches of efficient hydrolysis. Thus, the proposed modification route considerably lowers the cost of cellulose enzymatic hydrolysis.

Asn57 N-glycosylation promotes the degradation of hemicellulose by β-1,3-1,4-glucanase from Rhizopus homothallicus.

N-glycosylation alters the properties of different enzymes in different ways. Rhizopus homothallicus was first described as an environmental isolate from desert soil in Guatemala. A new gene encoding glucanase RhGlu16B was identified in R. homothallicus. It had high specific activity (9673 U/mg) when barley glucan was used as asubstrate, and β-glucan is hemicellulose that isabundant in nature. RhGlu16B has only one N-glycosylation site in its Ala55-Gly64 loop. It was found that N-glycosylation increased its Tm value and catalytic efficiency by 5.1°C and 59%, respectively. Adding N-glycosylation to the same region of GH16 family glucanases TlGlu16A (from Talaromyces leycettanus) increased its thermostability and catalytic efficiency by 6.4°C and 38%, respectively. In a verification experiment using GH16 family glucanases BisGlu16B (from Bisporus) in which N-glycosylation was removed, N-glycosylation also appeared to promote thermostability and catalytic efficiency. N-glycosylation reduced the overall root mean square deviation of the enzyme structure, creating rigidity and increasing overall thermostability. This study provided a reference for the molecular modification of GH16 family glucanases and guided the utilization of β-glucan in hemicellulose.

α-Synuclein phosphorylation at serine 129 occurs after initial protein deposition and inhibits seeded fibril formation and toxicity

α-Synuclein (α-syn) phosphorylation at serine 129 (pS129–α-syn) is substantially increased in Lewy body disease, such as Parkinson’s disease (PD) and dementia with Lewy bodies (DLB). However, the pathogenic relevance of pS129–α-syn remains controversial, so we sought to identify when pS129 modification occurs during α-syn aggregation and its role in initiation, progression and cellular toxicity of disease. Using diverse aggregation assays, including real-time quaking-induced conversion (RT-QuIC) on brain homogenates from PD and DLB cases, we demonstrated that pS129–α-syn inhibits α-syn fibril formation and seeded aggregation. We also identified lower seeding propensity of pS129–α-syn in cultured cells and correspondingly attenuated cellular toxicity. To build upon these findings, we developed a monoclonal antibody (4B1) specifically recognizing nonphosphorylated S129–α-syn (WT–α-syn) and noted that S129 residue is more efficiently phosphorylated when the protein is aggregated. Using this antibody, we characterized the time-course of α-syn phosphorylation in organotypic mouse hippocampal cultures and mice injected with α-syn preformed fibrils, and we observed aggregation of nonphosphorylated α-syn followed by later pS129–α-syn. Furthermore, in postmortem brain tissue from PD and DLB patients, we observed an inverse relationship between relative abundance of nonphosphorylated α-syn and disease duration. These findings suggest that pS129–α-syn occurs subsequent to initial protein aggregation and apparently inhibits further aggregation. This could possibly imply a potential protective role for pS129–α-syn, which has major implications for understanding the pathobiology of Lewy body disease and the continued use of reduced pS129–α-syn as a measure of efficacy in clinical trials.

The replacement of main cap domain to improve the activity of a ZEN lactone hydrolase with broad substrate spectrum

Zearalenone (ZEN) and its derivatives is a major kind of mycotoxins that being commonly detected in contaminated grain products. ZEN lactone hydrolase (ZHD) can hydrolyze ZEN to produce non-toxic product, providing an environment-friendly way for ZENs detoxification. However, most of ZEN derivatives are more toxic, which leads to a high demand for the novel ZHD with high degradation activity towards ZEN derivatives. Here, a new ZEN lactone hydrolase Zhd11B from Fonsecaea monophora was characterized to efficiently hydrolyze ZEN and more toxic derivatives α-ZAL and β-ZAL. The broad substrate spectrum of Zhd11B may attribute to the improved protein flexibility. Through cap-domain swap, the activity towards ZEN, α-ZAL and β-ZAL was further improved by 1.5-, 1.6- and 2.9-fold, respectively, which suggested that the conserved cap domain could be a structural element for ZHDs engineering, providing a new strategy for molecular modification of ZHDs. Structure comparison and molecular dynamic analysis showed that the protonation of catalytic histidine residue (H245 in Zhd11B) and a more stable combination between “goalkeeper” of the catalytic pocket are main determinant factors of ZHDs’ catalytic efficiency. Our results provide a good experimental material for better understanding of the mechanism of substrate specificity and cap domain swapping would provide a new strategy for the molecular modification.

Impact of regiochemistry on thermal stability of trifuroxan based energetic materials: A theoretical perspective

Improving the stability of energetic materials with high energy density has been an issue over the past decades. Regioisomerism, as an effective molecular modification strategy, shows the potential to improve the thermal stability of energetic materials without a compromise in energy density. In this study, the impacts of regioisomerism on thermal stabilities of two trifuroxan based energetic regioisomers (BFTF-1 and BFTF-2) have been thoroughly investigated. The initial decomposition mechanism has been studied to reveal the decomposition process. According to the Gibbs free energy profiles, NO2-dissociation path is proved as the primary decomposition path for both regioisomers, and the difference in energy also well explains their distinct thermal stabilities. The regioisomerism impacts on molecular structure and NO2 connection have been evaluated through intramolecular interactions and electron effects. The structure of BFTF-2 has been stabilized by an intramolecular electrostatic attraction, the connection of the leaving NO2 group in BFTF-1 has been weakened by intramolecular steric effect, both of which result in different thermal stabilities of BFTF-1 and BFTF-2.

Genetic Engineering Technologies for Improving Crop Yield and Quality

Genetic engineering refers to the specific molecular biological modification of DNA sequences. With the rapid development of genetic engineering methods, especially the breakthroughs in guiding endonuclease technology, gene remodeling of crops has become simpler, more precise, and efficient. Genetic engineering techniques can be used to develop crops with superior traits such as high trace elements and high plant nutrients, providing an important tool to meet the needs of nearly 7.6 billion people in the world for crop yield and quality and to achieve sustainable development. This review first introduces transgenic technology and gene editing technology and analyzes the achievements in improving the efficiency of genetic transformation and regeneration in recent years. Then, it focuses on reviewing the applications of related genetic engineering technologies in improving the yield and quality of rice, maize, and wheat. In addition, the problems of genetic engineering technology in crop applications are discussed. The aim is to provide a reference for research on the development of genetic engineering technologies and the improvement of crop yield and quality.

Crucial Residues of C-Terminal Oligopeptide C60 to Improve the Yield of Prebiotic Xylooligosaccharides by Truncated Mutation.

Increasing the yields of short xylooligosaccharides by enzymatic production is efficient to improve prebiotic effects. Previously, C-terminal oligopeptide C60 was found to accelerate short xylooligosaccharides. Herein, in order to further understand the molecular mechanism of C60, the sequence analysis firstly showed that C60 displays typical properties of a linker (rich in proline/alanine/glycine/glutamine/arginine, 8.33–20.00%). C60 shared the highest identity with the N-terminal region of esterase (98.33%) and high identity with the linker between xylanase and esterase from Prevotella sp. (56.50%), it is speculated to originate from an early linker between XynA and another domain. Besides, structure simulation showed that C60 enhances the molecular interactions between substrate and active residues to improve catalytic efficiency. Moreover, three truncated variants with different lengths of C-terminal regions were successfully generated in Escherichia coli. The specific activities of variants were 6.44–10.24 fold of that of XynA-Tr, and their optimal temperature and pH were the same as XynA-Tr. Three truncated variants released more xylooligosaccharides, especially xylobiose (46.33, 43.41, and 49.60%), than XynA-Tr (32.43%). These results are helpful to understand the molecular mechanism of C60, and also provide new insight to improve the yields of short xylooligosaccharides by molecular modification at the terminal of xylanases.

Engineering microbial consortia of Elizabethkingia meningoseptica and Escherichia coli strains for the biosynthesis of vitamin K2

BackgroundThe study and application of microbial consortia are topics of interest in the fields of metabolic engineering and synthetic biology. In this study, we report the design and optimisation of Elizabethkingia meningoseptica and Escherichia coli co-culture, which bypass certain limitations found during the molecular modification of E. meningoseptica, such as resistance to many antibiotics and fewer available molecular tools.ResultsThe octaprenyl pyrophosphate synthase from E. meningoseptica sp. F2 (EmOPPS) was expressed, purified, and identified in the present study. Then, owing to the low vitamin K2 production by E. coli or E. meningoseptica sp. F2 monoculture, we introduced the E. meningoseptica and E. coli co-culture strategy to improve vitamin K2 biosynthesis. We achieved production titres of 32 mg/L by introducing vitamin K2 synthesis-related genes from E. meningoseptica sp. F2 into E. coli, which were approximately three-fold more than the titre achieved with E. meningoseptica sp. F2 monoculture. This study establishes a foundation for further engineering of MK-n (n = 4, 5, 6, 7, 8) in a co-cultivation system of E. meningoseptica and E. coli. Finally, we analysed the surface morphology, esterase activity, and membrane permeability of these microbial consortia using scanning electron microscopy, confocal laser scanning microscopy, and flow cytometry, respectively. The results showed that the co-cultured bacteria were closely linked and that lipase activity and membrane permeability improved, which may be conducive to the exchange of substances between bacteria.ConclusionsOur results demonstrated that co-culture engineering can be a useful method in the broad field of metabolic engineering of strains with restricted molecular modifications.

Effect of main chain modification during reversion on strain‐induced crystallization of polyisoprene rubbers

AbstractThe effect of main chain modification during reversion on strain‐induced crystallization (SIC) of unfilled natural rubber (NR) and synthetic polyisoprene rubber (IR) cured with a conventional vulcanization system has been investigated. To eliminate the interference of crosslink density, vulcanizates were prepared using different amounts of curatives, chosen to give mainly monosulfidic or carbon–carbon crosslinks, having similar crosslink densities to the conventional compound at different states of reversion. Crystallinity was characterized by the degree of stress softening, and the contents of trans‐methine were qualitatively and quantitatively analyzed by Fourier transform infrared spectroscopy. It was found that crosslink density exerts much greater influence on crystallinity than crosslink structure. At the same crosslink density, SIC of NR vulcanizates after reversion is lower than that of samples cured with tetramethylthiuram disulfide or dicumyl peroxid to the optimum cure state, which might be attributed to molecular main chain modification during reversion. NR was found to have better reversion resistance than IR.

PAEs Derivatives' Design for Insulation: Integrated In-Silico Methods, Functional Assessment and Environmentally Friendly Molecular Modification.

As a common substance in production and life, phthalic acid esters (PAEs), the main component of plastics, have brought more and more serious problems to the environment. This study normalized the insulation, toxicity, and bioconcentration data of 13 PAEs to eliminate the dimensional coefficients of each index, and then used the comprehensive index method to calculate the comprehensive effect value of PAEs with three properties. The comprehensive effect value was used as the data source to construct the 3D-QSAR model of PAE molecular comprehensive effect. The DAP was selected as the target molecule, the distribution of each force field in the three-dimensional equipotential map was analyzed, and 30 molecular modification schemes were created. The constructed single-effect models of insulation, toxicity, and bioconcentration of PAEs and the scoring function module of DS software were used to evaluate the stability and environmental friendliness of PAE derivative molecules. Four PAE derivatives were screened for increased comprehensive effects, enhanced insulation, and reduced toxicity and bioconcentration. By calculating the binding energy of the target molecule and the derivative molecule with the degrading enzyme under different applied electric fields, it was found that the binding energy of DAP-1-NO2-2-CH2C6H5 decreases more than DAP does when there is an applied electric field, indicating that the degradation ability of degrading enzymes on PAE derivative molecules is reduced, which indirectly proves that the insulation is enhanced. The innovation of this paper lies in the insulation, toxicity, and bioenrichment data of PAEs being processed by mathematical method for the first time, and PAEs with high insulation, low toxicity, and low bioconcentration were designed by building a comprehensive model.

Polysaccharides as Potential Anti-tumor Biomacromolecules -A Review.

Cancer, as one of the most life-threatening diseases, has attracted the attention of researchers to develop drugs with minimal side effects. The bioactive macromolecules, such as the polysaccharides, are considered the potential candidates against cancer due to their anti-tumor activities and non-toxic characteristics. The present review provides an overview on polysaccharides' extraction, isolation, purification, mechanisms for their anti-tumor activities, structure-activity relationships, absorption and metabolism of polysaccharides, and the applications of polysaccharides in anti-tumor therapy. Numerous research showed extraction methods of polysaccharides had a significant influence on their activities. Additionally, the anti-tumor activities of the polysaccharides are closely related to their structure, while molecular modification and high bioavailability may enhance the anti-tumor activity. Moreover, most of the polysaccharides exerted an anti-tumor activity mainly through the cell cycle arrest, anti-angiogenesis, apoptosis, and immunomodulation mechanisms. Also, recommendations were made to utilize the polysaccharides against cancer.