Molecular Modification Research Articles

Molecular structure modification of ovalbumin through controlled glycosylation with dextran for its emulsibility improvement

Ovalbumin (OVA) is a high nutritious protein, but the poor emulsibility limited its application. The present study glycosylated OVA with dextran (Dex) by controlled wetheating (60–90 °C for 3 h). Temperature was an inductive factor for glycosylation degree (DG and browning intensity), and higher temperature could accelerate the reaction. Variations in molecular structure of OVA were analyzed by SDS-PAGE, FTIR, fluorescence spectroscopy and UV spectroscopy, which verified successes in the generation of glycoconjugate with more flexible structure. Emulsifying activity index (EAI) and emulsion stability index (ESI) for the emulsion of OVA-Dex glycoconjugates were significantly enhanced with the increasing of glycosylation temperature. Moreover, confocal laser scanning results revealed that the emulsion exhibited smaller size and more uniform distribution, and slower transmission profiles were checked by LUMiSizer centrifugal analysis as well, confirming the emulsibility improvement of OVA. Thus, controlled glycosylation reaction is an available method to improve the emulsifying properties of OVA.

Identification of Two Myrosinases from a Leclercia adecarboxylata Strain and Investigation of Its Tolerance Mechanism to Glucosinolate Hydrolysate.

Glucosinolates (GSLs), secondary metabolites synthesized by cruciferous plants, can be hydrolyzed by myrosinase into compounds, such as isothiocyanates (ITCs), with various bioactivities. Thus, myrosinase plays an important role in the utilization of GSLs. We isolated a bacterial strain, which was identified as Leclercia adecarboxylata, from the rhizosphere soil of rape seedlings and identified two myrosinase genes and an ITC hydrolase gene. Both myrosinases are intracellular and have 658 amino acid residues. Via molecular docking and chemical modification assays investigating the active sites of the myrosinases, arginine was found to be essential for their catalytic activity. Transcriptomic analysis of the response to sinigrin revealed significant up-regulation of some genes involved in allyl-ITC detoxification, with metallo-β-lactamase 3836 having the highest fold change. Thus, we discovered two myrosinases from L. adecarboxylata and demonstrated that the mechanism of tolerance of the bacterium to allyl-ITC likely involved metallo-β-lactamase activity.

Inhibiting Phase Transfer of Protein Nanoparticles by Surface Camouflage-A Versatile and Efficient Protein Encapsulation Strategy.

Engineering a system with a high mass fraction of active ingredients, especially water-soluble proteins, is still an ongoing challenge. In this work, we developed a versatile surface camouflage strategy that can engineer systems with an ultrahigh mass fraction of proteins. By formulating protein molecules into nanoparticles, the demand of molecular modification was transformed into a surface camouflage of protein nanoparticles. Thanks to electrostatic attractions and van der Waals interactions, we camouflaged the surface of protein nanoparticles through the adsorption of carrier materials. The adsorption of carrier materials successfully inhibited the phase transfer of insulin, albumin, β-lactoglobulin, and ovalbumin nanoparticles. As a result, the obtained microcomposites featured with a record of protein encapsulation efficiencies near 100% and a record of protein mass fraction of 77%. After the encapsulation in microcomposites, the insulin revealed a hypoglycemic effect for at least 14 d with one single injection, while that of insulin solution was only ∼4 h.

Structure Characteristics, Biochemical Properties, and Pharmaceutical Applications of Alginate Lyases.

Alginate, the most abundant polysaccharides of brown algae, consists of various proportions of uronic acid epimers α-L-guluronic acid (G) and β-D-mannuronic acid (M). Alginate oligosaccharides (AOs), the degradation products of alginates, exhibit excellent bioactivities and a great potential for broad applications in pharmaceutical fields. Alginate lyases can degrade alginate to functional AOs with unsaturated bonds or monosaccharides, which can facilitate the biorefinery of brown algae. On account of the increasing applications of AOs and biorefinery of brown algae, there is a scientific need to explore the important aspects of alginate lyase, such as catalytic mechanism, structure, and property. This review covers fundamental aspects and recent developments in basic information, structural characteristics, the structure–substrate specificity or catalytic efficiency relationship, property, molecular modification, and applications. To meet the needs of biorefinery systems of a broad array of biochemical products, alginate lyases with special properties, such as salt-activated, wide pH adaptation range, and cold adaptation are outlined. Withal, various challenges in alginate lyase research are traced out, and future directions, specifically on the molecular biology part of alginate lyases, are delineated to further widen the horizon of these exceptional alginate lyases.

Enhanced catalytic activity of recombinant transaminase by molecular modification to improve L-phosphinothricin production

Transaminases catalyze the transfer of an amino group from a donor to a keto group of an acceptor substrate and are applicable to the asymmetric synthesis of herbicide L-phosphinothricin (L-PPT). Here, the important residue sites (C390, I22, V52, R141, Y138 and D239) of transaminase from Salmonella enterica (SeTA) were modified at the adjacency of the substrate-binding pocket to improve the enzyme activity. Among the constructed mutant library, the SeTA-Y138F mutant displayed higher activity than the wild-type enzyme. Compared to the wild-type, SeTA-Y138F showed improved catalytic efficiency with a 4.36-fold increase. The Km and kcat of SeTA -Y138F toward 4-(hydroxy(methyl) phosphoryl)-2-oxobutanoic acid (PPO) were 26.39 mM and 34.28 s−1, respectively. Subsequently, the three-enzyme co-expression system of E. coli BL21 (DE3)/pACYCDuet-SeTA-Y138F/pETDuet-AlaDH-BsGDH was developed by combining a alanine dehydrogenase (AlaDH) to recycle the byproduct of amino donor, a glucose dehydrogenase (BsGDH) for cofactor recycling. Under the optimized conditions, an excellent L-PPT yield of 90.8% was achieved by the whole-cell biotransformation with 500 mM PPO. It exhibited the tri-enzymatic coupling system was potential for effective production of target L-PPT.

In Situ Observation of Ferroelastic Domain and Phase Transition in a Three‐Dimensional Molecular Crystal

Massive efforts have been devoted to designing molecular ferroic materials by molecular modification. For molecular ferroelastic, previous work is focused on the temperature-dependent ferroelastic domains, however, few are related to controlling the ferroelastic domain by the stress. Inspired by the "quasi-spherical theory" and fluorination effect, we designed a more flexible (MedabcoF)2+ (MedabcoF=1-fluoro-4-methyl-1,4-diazoniabicyclo[2.2.2]octane) cation by introducing a methyl group and a fluorine atom at the two symmetrical ends of the Dabco (1,4-diazoniabicyclo[2.2.2]octane) and synthesized a hybrid 3D perovskite (MedabcoF)Rb(BF4 )3 (1) which displays three reversible phase transitions accompanying dual ferroelastic behavior. Besides, it not only exhibits ferroelastic domains switching by the thermal stimulation, and the sensitive reaction of in situ domains under the stress of it is also realized. This work not only achieves a force-controlled ferroelastic domain but develops a more profound comprehension of the relationship between the thermal motion behavior of guest cations and the intriguing properties of materials.

Molecular modifications on β-nitro-styrene derivatives increase their antioxidant capacities

• Theoretical and experimental studies using molecular calculation and DPPH evaluation were performed on β-nitro-styrene derivatives. • Four molecular modifications were proposed on benzene or alkene moieties using electron donating groups (EDGs) or electron withdrawing groups (EWGs). • Their antioxidant capacity can be increased by using EDGs substituted on β or para positions. • New derivatives can be proposed. β-Nitro-styrenes among other nitroderivatives are known due to their high electrophilicity and low electron donation capacities. A preferential molecular modification on 1-nitro-2-phenylethene was analyzed by DFT method in B3LYP/6-311++G(2d,2p) level of theory on gas phase seeking to increase its electron donating capacity. For this, four molecular modifications were proposed showing the impact of alkene moiety, substitutions on β or para positions using electron donating groups (EDGs) or electron withdrawing groups (EWGs). The para is the preferential position for methylation when compared to ortho or meta positions. Our results show that EDGs increase the redox capacity in β and para positions and decrease the electrophilicity when compared to EWGs. The increase on electron donation capacity is in accordance with DPPH evaluation and β-nitro-phenylethene derivatives still are poor antioxidants. Therefore, the antioxidant capacity on β-nitro-phenylethene can be increased by using EDGs substituted on β or para positions.

Chemically tailored molecular surface modification of cellulose nanofibrils for manipulating the charge density of triboelectric nanogenerators

Studying the surface chemical composition of materials is greatly significant to further understand the triboelectric charge generated during contact electrification. Although it has been studied to modify material surfaces by chemical methods to change the charge density, understanding the effect more systematically has not been elucidated in detail. In this work, silane coupling agents with the same main chain but different terminal functional groups were selected to chemically tailor cellulose nanofibrils. The results show that surface charge density of a material can be altered by introducing functional groups with different electron-withdrawing or electron-donating abilities to its surface. By regulating the number and density of the functional groups, the range of the charge density can be tailored more specifically. More importantly, a relatively systematic and improved mechanism is proposed to clarify the influence of chemically tailored surfaces on contact electrification. This article provides guidance for the systematic study of chemically tailored molecular surface modification to control triboelectric charge density.

An uncharacterized protein from the metagenome with no obvious homology to known lipases shows excellent alkaline lipase properties and potential applications in the detergent industry.

A novel lipase, Lip486, which has no obvious homology with known lipases, was discovered using functional metagenomics technology. Phylogenetic tree analysis suggested that the enzyme belongs to a new subfamily called lipolytic enzyme family II. To explore the enzymatic properties, lip486 was expressed heterologously and efficiently in Escherichia coli. The recombinant enzyme displayed the highest activity on the substrate p-nitrophenyl caprate with a carbon chain length of 10, and its optimum temperature and pH were 53°C and 8.0, respectively. The recombinant Lip486 showed good activity and stability in strong alkaline and medium-low-temperature environments. The results of compatibility and soaking tests showed that the enzyme had good compatibility with 4 kinds of commercial detergents, and an appropriate soaking time could further improve the enzyme activity. Oil stain removal test results for a cotton cloth indicated that the washing performance of commercial laundry detergent supplemented with Lip486 was further improved. In addition, as one of the smallest lipases found to date, Lip486 also has the advantages of high yield, good stability and easy molecular modification. These characteristics reflect the good application prospects for Lip486 in the detergent and other industries in the future.

Temperature-induced response in algal cell surface properties and behaviour: an experimental approach

Microalgae are considered an accurate indicator of ecosystem perturbations induced by global climate change. The present work aims to investigate the alteration of temperature on surface properties and behaviour of three algal species using the complementary surface methods (electrochemical and atomic force microscopy). The results showed that the temperature-induced response of algae is species-specific due to the structural features of the cell envelope. Wall-less algae experience the largest nanomechanical and chemical change, while algae with silicified walls show the pronounced chemical change in the degree of hydrophobicity. Alterations of surface properties suggest a molecular modification of the algal barrier and cytoskeletal rearrangements due to a change in cell size, while algal morphology reveals no change. The physiological activity of cells showed a different organisation of released extracellular substances in the form of fine fibrillar structures, aggregated particles, and dense networks. Both types of algal responses, physiological activity, and molecular modification of the cell barrier determine the cell adhesion and motility. This study highlights the role of surface properties in cell-substrate and cell–cell interactions, which is important for the understanding of algal behaviour at natural interfaces and the mechanism of algal biofilm and aggregate formation in aquatic systems under the stress.Graphical abstract

Overview of a bioremediation tool: organophosphorus hydrolase and its significant application in the food, environmental, and therapy fields.

In the past decades, the organophosphorus compounds had been widely used in the environment and food industries as pesticides. Owing to the life-threatening and long-lasting problems of organophosphorus insecticide (OPs), an effective detection and removal of OPs have garnered growing attention both in the scientific and practical fields in recent years. Bacterial organophosphorus hydrolases (OPHs) have been extensively studied due to their high specific activity against OPs. OPH could efficiently hydrolyze a broad range of substrates both including the OP pesticides and some nerve agents, suggesting a great potential for the remediation of OPs. In this review, the microbial identification, molecular modification, and practical application of OPHs were comprehensively discussed.Key points• Microbial OPH is a significant bioremediation tool against OPs.• Identification and molecular modification of OPH was discussed in detail.• The applications of OPH in food, environmental, and therapy fields are presented.

Evolving strategies for marine enzyme engineering: recent advances on the molecular modification of alginate lyase.

Alginate, an acidic polysaccharide, is formed by β-d-mannuronate (M) and α-l-guluronate (G). As a type of polysaccharide lyase, alginate lyase can efficiently degrade alginate into alginate oligosaccharides, having potential applications in the food, medicine, and agriculture fields. However, the application of alginate lyase has been limited due to its low catalytic efficiency and poor temperature stability. In recent years, various structural features of alginate lyase have been determined, resulting in modification strategies that can increase the applicability of alginate lyase, making it important to summarize and discuss the current evidence. In this review, we summarized the structural features and catalytic mechanisms of alginate lyase. Molecular modification strategies, such as rational design, directed evolution, conserved domain recombination, and non-catalytic domain truncation, are also described in detail. Lastly, the application of alginate lyase is discussed. This comprehensive summary can inform future applications of alginate lyases.

Expanding the Structural Diversity and Functional Scope of Diphenylalanine-Based Peptide Architectures by Hierarchical Coassembly.

Modulation of the structural diversity of diphenylalanine-based assemblies by molecular modification and solvent alteration has been extensively explored for bio- and nanotechnology. However, regulation of the structural transition of assemblies based on this minimal building block into tunable supramolecular nanostructures and further construction of smart supramolecular materials with multiple responsiveness are still an unmet need. Coassembly, the tactic employed by natural systems to expand the architectural space, has been rarely explored. Herein, we present a coassembly approach to investigate the morphology manipulation of assemblies formed by N-terminally capped diphenylalanine by mixing with various bipyridine derivatives through intermolecular hydrogen bonding. The coassembly-induced structural diversity is fully studied by a set of biophysical techniques and computational simulations. Moreover, multiple-responsive two-component supramolecular gels are constructed through the incorporation of functional bipyridine molecules into the coassemblies. This study not only depicts the coassembly strategy to manipulate the hierarchical nanoarchitecture and morphology transition of diphenylalanine-based assemblies by supramolecular interactions but also promotes the rational design and development of smart hydrogel-based biomaterials responsive to various external stimuli.

Strategies to Control Human Health Risks Arising from Antibiotics in the Environment: Molecular Modification of QNs for Enhanced Plant-Microbial Synergistic Degradation.

In the present work, a comprehensive screening and evaluation system was established to improve the plant–microbial synergistic degradation effects of QNs. The study included the construction of a 3D-QSAR model, the molecular modification, environmental friendliness and functional evaluation of drugs, degradation pathway simulation, and human health risk assessment. Molecular dynamics was applied to quantify the binding capacity of QNs toward the plant degradation enzyme (peroxidase) and microbial degradation enzymes (manganese peroxidase, lignin peroxidase, and laccase). The fuzzy comprehensive evaluation method was used in combination with the weighted average method for normalization and assigning equal weights to the plant and microbial degradation effect values of the QNs. Considering the synergistic degradation effect value as the dependent variable and the molecular information of the QNs as the independent variable, a 3D-QSAR model was constructed for the plant–microbial synergistic degradation effect of QNs. The constructed model was then employed to conduct the molecular modification, environmental friendliness and functional evaluation, degradation pathway simulation, and human health risk assessment of transformation products using pharmacokinetics and toxicokinetics. The results revealed that the synergistic degradation effect 3D-QSAR (CoMSIA) model exhibited good internal and external prediction ability, fitting ability, stability, and no overfitting phenomenon. Norfloxacin (NOR) was used as the target molecule in the molecular modification. A total of 35 NOR derivatives with enhanced plant–microbial synergistic degradation effect (1.32–21.51%) were designed by introducing small-volume, strongly electronegative, and hydrophobic hydrogen bond receptor groups into the active group of the norfloxacin structure. The environment-friendliness and the functionality of NOR were evaluated prior to and after the modification, which revealed seven environment-friendly FQs derivatives exhibiting moderate improvement in stability and bactericidal efficacy. The simulation of the NOR plant and microbial degradation pathways prior to and after the modification and the calculation of the reaction energy barrier revealed Pathway A (D-17 to D-17-2) and Pathway B (D-17 to D-17-4) as the most prone degradation pathways in plants and Pathway A (D-17 to D-17-1) and Pathway B (D-17 to D-17-4) as the most prone degradation pathways in microorganisms. This demonstrated that the degradation of the modified NOR derivatives was significantly enhanced, with the hydroxylation and piperazine ring substitution reaction playing an important role in the degradation process. Finally, the parameters, including hepatotoxicity, mutagenicity, and rodent carcinogenicity, among others, predicted using the pharmacokinetics and toxicokinetics analyses revealed a significant reduction in the human health risk associated with the modified NOR, along with a considerable reduction in the toxicity of its transformation products, implying that the human health risk associated with the transformation products was reduced remarkably. The present study provides a theoretical basis for novel ideas and evaluation programs for improving the plant–microbial synergistic degradation of the QNs antibiotics for source control and drug design, thereby reducing the residues of these antibiotics and the associated hazard in the complex plant–soil environment, ultimately decreasing the potential risks to human health.

Molecular modification and assembly at cell surface for biochemical analysis

<p indent=0mm>Nature has presented multi-scale, multi-level, and multi-functionally assembled systems during evolution, from single-cell to the higher organisms of multi-cell systems. In the course of both physiological and disease processes, cells carry out a series of molecular events at their surface to promote intracellular communication, thus driving cell proliferation, differentiation and migration. A collection of these interacted cells of different types can help to construct a living system with complete functions. Therefore, the development of molecular modification and assembly technologies at cell surface is the key to explore cell interfacial behavior at the molecular level, which may help to understand interfacial molecular events and biochemical reactions. Meanwhile, molecular modification and assembly technologies can greatly promote the advance of many research and application fields, including biosensing, disease diagnosis, translational medicine, and tissue engineering. Therefore, this review will present the latest research progress, so as to systematically describe the use of molecular probes and assembled materials at the cell surface, such as DNA and peptides, and thus give an outlook on their prospects for analytical applications.

Extraction Techniques, Biological Activities and Health Benefits of Marine Algae Enteromorpha prolifera Polysaccharide.

There is increasing interest in the use of marine algae as functional food additives for improving human health. Enteromorpha (Ulva) prolifera (E. prolifera) is a seaweed green alga (Chlorophyta) that contains many bioactive compounds, of which polysaccharide is the main component. With the advancement of technology in the methods of extraction and analysis, recent studies in in vitro and animals model showed that polysaccharides derived from E. prolifera exert various biological activities, such as gut microbiota modulation, immunomodulation, antioxidant, antidiabetic, antimicrobial, and hypolipidemic. Research evidence has shown that methods of extraction and molecular modification, such as degradation, carboxymethylation, and sulfonation could alter the biological activities of polysaccharides. Therefore, in this review, we discussed the different extraction techniques, structural-activity relationship, and health benefits of sulfated polysaccharides derived from E. prolifera, and suggested future research avenues. This review helps to advance the extraction techniques and promote the application of marine algae polysaccharides as functional food and therapeutic agent.

A 3D-QSAR model for the comprehensive bioenrichment and biodegradation effect of benzotriazole ultraviolet stabilisers and application of the model in molecular modification.

Ultraviolet (UV) absorber, a type of light stabiliser, has received considerable attention because of its high bioenrichment ability and low biodegradability. In this study, benzotriazole ultraviolet stabilisers (BUVSs) were used as the research object, and the bioenrichment and biodegradation data of 13 types of BUVS molecules were subjected to dimensionless processing through quartile data transformation. Additionally, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed for the investigation of the comprehensive effect of molecular bioenrichment and biodegradation of BUVSs, and improved derivative molecules were designed. Furthermore, the validity of the model was predicted using EPI simulation software, and finally, the biodegradability of BUVSs and their bioenrichment and biological effect before and after modification in the food chain and in the aerobic and anaerobic bacteria in sewage were analysed through the molecular docking technology. A total of 10 derivatives with reduced enrichment ability and enhanced degradability were designed using the CoMFA model analysis (reduction: combined effect value, 0.32-20.55%; log BCF, 2.37-17.59%; and log HL, 0.47-16.94%). Molecular docking showed that the bioenrichment ability of two derivative molecules in the four organisms was decreased by 1.87-27.67%, and the biodegradation ability of four derivative molecules in the three sewage bacteria was enhanced by 1.60-33.38% compared with those before modification. The molecular modification method of UV absorbent developed in this study provides a new perspective for further studies on environment-friendly UV absorbent and helps reduce the risks of these emerging pollutants on the environment and human body.

Lipidomic profiling reveals molecular modification of lipids in hepatopancreas of juvenile mud crab (Scylla paramamosain) fed with different dietary DHA/EPA ratios

Untargeted lipidomic analysis was conducted to explore how different dietary docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio and, specifically, how an optimal ratio (2.3) compared to a suboptimum ratio (0.6) impacted lipid molecular species and the positional distribution of fatty acids in hepatopancreas of mud crab. The results indicated that major category of lipid affected by dietary DHA/EPA ratio was glycerophospholipids (GPs). The optimum dietary DHA/EPA ratio increased the contents of DHA bound to the sn-2 and sn-3 positions of phosphatidylcholine (PC) and triacylglycerol, EPA bound to the sn-2 position of phosphatidylcholine and 18:2n-6 bound to the sn-2 position of phosphatidylethanolamine (PE). Increased dietary DHA/EPA ratio also led to competition between arachidonic acid (ARA) and 18:2n-6 bound to esterified sites. Appropriate dietary DHA/EPA ratio can not only improve the growth performance and nutritional quality of mud crab, but also provide higher quality products for human consumers.

Toxicity inhibition strategy of microplastics to aquatic organisms through molecular docking, molecular dynamics simulation and molecular modification

In the present study, the combined toxic effect of microplastics and their additives (five) on aquatic organisms (zebrafish) was studied using full factorial design method, molecular docking, and molecular dynamics (MD) simulation technology. The aquatic toxicity control programmer was designed to improve the optimal combination of plasticizer and microplastics based on the design of environment-friendly phthalic acid ester (PAE) derivatives. First, a total of 64 groups of microplastic-additives were designed using the full factorial design method. Next, the microplastic-additives and aquatic receptor protein were docked together, and the binding energy of these complexes was calculated using the MD simulation method. The results revealed that the aquatic toxicity effects of different microplastic-additive combinations were variable; therefore, the optimal combination of microplastics exhibiting the lowest aquatic toxicity effect could be screened out. Base on the analyzing the bonding effect and surrounded amino acid residues between the microplastic additives and receptor protein, the main driving forces for the binding of the microplastic-additive and the protein were hydrophobic force, hydrogen bonding force and electrostatic force. The main effects and the second-order interaction of the microplastic-additives combination were analyzed using the fixed-effect model. The main additives that affect the aquatic toxicity of the microplastics can be known. In addition, based on the MD simulation of the molecular replacement of PAE derivatives, the optimal level of component combination of low aquatic toxicity effect of microplastics was constructed.

Plant-derived UDP-glycosyltransferase and Its Molecular Modification

Plant-derived UDP-glycosyltransferase and Its Molecular Modification