Ganoderma lucidum polysaccharides (GLP) as one of water-soluble polysaccharides has attracted much attention because of its bioactivities, especially antioxidant activity. Deproteinization is an ...essential step in the purification process of polysaccharides. In this study, three classic deproteinization methods, including neutral protease method, TCA precipitation and CaCl2 salting out, were evaluated for crude GLP processing. The methods had ability to remove proteins (71.50–87.36%), and meanwhile polysaccharide loss (8.35–11.39%) was observed. Structure analysis indicated that these deproteinization methods had no significant effect (p > 0.05) on molecular weight of polysaccharides, but led to varying degrees of glycoside bond losses (1.14–64.05%). Moreover, the antioxidant activities of deproteinized polysaccharides were measured in vitro by hydroxyl radical, reducing power, 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) free radical and ferric-reducing antioxidant power tests. Purified GLP by enzymolysis maintained the strongest antioxidants activities with the retention rate of over 47.40%, and its deproteinization efficiency and polysaccharide loss ratio were 74.03% and 11.39% respectively. In view of relatively high purity and antioxidant activity, enzymolysis was a suitable deproteinization method for GLP production.
•Three deproteinization methods were evaluated for GLP.•Deproteinization had no significant effect on main functional groups.•Different deproteinization methods led to various losses of glucoside bonds.•Deproteinization processes affected antioxidant activities at varying degree.•Enzymolysis was an optimal deproteinization method for GLP.
Little information is available concerning the structural features of nucleotide pyrophosphatase/phosphodiesterases (NPPs) of plant origin and the crystal structures of these proteins have not yet ...been reported. The aim of this study was to obtain insight into these aspects by carrying out a comparative analysis of the sequences of two different fragments of an NPP from the latex of the Mediterranean shrub Euphorbia characias (ELNPP) and by studying the low‐resolution structure of the purified protein in solution by means of small‐angle X‐ray scattering. This is the first structure of a plant NPP in solution that has been reported to date. It is shown that the ELNPP sequence is highly conserved in many other plant species. Of note, the catalytic domains of these plant NPPs have the same highly conserved PDE‐domain organization as mammalian NPPs. Moreover, ELNPP is a dimer in solution and this oligomerization state is likely to be common to other plant enzymes.
The low‐resolution 3D structure of a plant nucleotide pyrophosphatase/phosphodiesterase (NPP) solved by small‐angle X‐ray scattering is reported. The general structural features of plant NPPs are inferred. Structural analogies with, and differences from, mammalian NPPs are discussed.
•Formulation of TMD-PSEH system attached to an undamped primary structure.•Extension of the fixed point theory to the TMD-PSEH system.•Close-form expression of optimal tuning, damping, and resistance ...ratios.•Insight into the power flow analysis.•Performance of the system along with attendant numerical simulations.
A tuned mass damper with a piezoelectric stack energy harvester (TMD-PSEH) is a passive vibration control device for the dual purpose of absorbing vibration and harvesting energy. This paper develops the fixed point theory for the optimal design of a TMD-PSEH attached to an undamped primary structure under harmonic external excitation. It has been proven that the existence of two fixed points of the amplitude-frequency curve doest not depend on the damping of the primary structure. Based on the requirements for suppressing the vibration of the primary structure and enlarging the harvested power, the analytical expressions for the optimal tuning, damping, and resistance ratios are determined. It is found that the minimum damping ratio occurs in the vicinity of the electrical resistance ratio α=1 for various values of the electromechanical coupling coefficient. Power flow analysis is carried out resulting in closed-form expressions of instantaneous and average powers. Numerical examinations of the system with the obtained optimal parameters are performed demonstrating a very good compatibility between theory and computation. In addition, the effect of damping in the primary structure is also investigated. It is shown that not only the vibration of the primary structure effectively reduces, but also a large amount of the harvested energy can be captured in the main resonance region.
•Extended theoretical framework and discrete element approaches are developed.•Performance-related morphological and mechanical parameters are obtained.•Contact force, contact points and ...stress–strain curves are extracted from simulation.•Load carrying capacity is identified by critical sieve sizes of primary structure.•The disruption factor and secondary strain are indicators of rutting performance.
The gradation and mechanical properties of aggregates impressively affect the load carrying capacity and rutting resistance of asphalt mixtures. They are able to provide some fundamental parameters that are linked to mixture performance. In order to accurately detect critical controlled sizes and obtain more fundamental parameters that can characterize load carrying capacity and rutting resistance of asphalt mixtures, this paper aims to develop a mechanics-based approach to evaluate aggregate gradation, which contains the theoretical packing analysis and discrete element simulation.
An extended theoretical morphology framework is developed by checking the local and global interlock of graded aggregates in the theoretical packing analysis. The sieve size range of primary structure which has an interactive interlock can be determined in the local interlock check model. The relationship between the transferred force and the induced force is proposed in the densest and loosest packing arrangements, respectively. The morphological parameters of disruption factor and weighted average size for the global scale are also proposed in theoretical packing analysis.
Then the discrete element method is used to validate the theoretical framework. The advanced gradation input algorithm procedure is established in the discrete element simulation to simulate the compression test of graded aggregates. The mechanical parameters of contact force, contact points and stress–strain curves are extracted from the simulation results.
The results show that the discrete element method can validate the theoretical framework and output the performance related parameters. The contact force analysis shows that the aggregates retaining on sieve sizes of 2.36 and 4.75 mm provide more than 50% contribution to resist load, and the aggregates retaining on sieve sizes of 1.18, 0.6 and 0.3 mm provide more than 50% contribution to stabilize the structure. The coordination number analysis suggests that the gradation with more fine aggregates might lead to a greater number of voids but smaller air-void size when the asphalt content and porosity remain constant. The stress–strain curve analysis shows that the modulus and secondary strain are highly related to the rutting performance of an asphalt mixture.
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•The primary structure of TLR4-related polysaccharides was described in detail.•The dual-directional immune regulation of TLR4-related polysaccharides was summarized.•The 3D ...interaction model of polysaccharides to TLR4-MD2 complex was hypothesized.
Various structural types of polysaccharides are recognized by toll-like receptor 4 (TLR4). However, the mechanism of interaction between the polysaccharides with different structures and TLR4 is unclarified. This review summarized the primary structure of polysaccharides related to TLR4, mainly including molecular weight, monosaccharide composition, glycosidic bonds, functional groups, and branched-chain structure. The optimal primary structure for interacting with TLR4 was obtained by the statistical analysis. Besides, the dual-directional regulation of TLR4 signaling cascade by polysaccharides was also elucidated from an immune balance perspective. Finally, the 3D interaction model of polysaccharides to TLR4-myeloid differentiation factor 2 (MD2) complex was hypothesized according to the LPS-TLR4-MD2 dimerization model and the polysaccharides solution conformation. The essence of polysaccharides binding to TLR4-MD2 complex is a multivalent non-covalent bond interaction. All the arguments summarized in this review are intended to provide some new insights into the interaction between polysaccharides and TLR4.
Structure of Animal Silks Zhang, Wenwen; Fan, Yimin
Methods in molecular biology (Clifton, N.J.),
2021, Letnik:
2347
Journal Article
As an abundant fibrous protein, animal silks have received a variety of interests in both traditional and high-tech industries, such as textiles, decoration, and biomedicine, due to their unique ...advantages in mechanical performance, sustainability, biocompatibility, and biodegradability. While developing applications of animal silks, the structure of animal silks has also received more and more attention in these decades. Briefly, most animal silks can be considered as semicrystalline fibers, which are composed of β-sheet nanocrystals and amorphous regions. However, different animal silks have similarities and also have obvious differences at different structural levels. In this chapter, we will introduce the structures of the three most representative animal silks, that is, spider dragline silk, tussah silk, and mulberry silk. The similarities and differences in their structures will be highlighted, so as to provide fundamental guidance for the research and use of these animal silks.
Properties of short-chain antimicrobial peptides (AMPs) depend on their primary structures. Brevibacillus laterosporus was previously found to secrete five AMPs. Herein, we discovered ...exogenously-added l-valine could regulate this strain to produce novel AMPs (named as Brevilaterin V) with new primary structures. Five novel Brevilaterins V with linear peptides were purified and characterized. They had high antimicrobial activities against 10 tested pathogenic bacteria. Brevilaterins V exhibited a good stability even treatment at 100 °C, or pH 2 or pH 12, for 2 h. Interestingly, all novel Brevilaterins V showed low hemolytic activities. In particular, the hemolytic rates of Brevilaterin V1 and Brevilaterin V2 were <5%; however, single changes in primary structure or a single extra methylene in the N-terminal fatty acid chain increase the hemolytic activity. The strategy of using amino acids in culture medium to regulate AMPs production by Br. laterosporus provides a basis for improvement of the range and properties of known AMPs.
•l-Valine regulates Brevibacillus laterosporus to produce new antimicrobial peptides.•This regulation strategy is the first report for improving the properties of AMPs.•New found AMPs exhibit high antibacterial activities but low hemolytic activities.
Microalgal-bacterial symbioses are prevalent in aquatic ecosystems and play a pivotal role in carbon sequestration, significantly contributing to global carbon cycling. The understanding of the ...contribution of exopolysaccharides (EPSs), a crucial carbon-based component, to the structural integrity of microalgal-bacterial symbioses remains insufficiently elucidated. To address this gap, our study aims to enhance our comprehension of the composition and primary structure of EPSs within a specific type of granular microalgal-bacterial symbiosis named microalgal-bacterial granular sludge (MBGS). Our investigation reveals that the acidic EPSs characteristic of this symbiosis have molecular weights ranging from several hundred thousand to over one million Daltons, including components like glucopyranose, galactopyranose, mannose, and rhamnose. Our elucidation of the backbone linkage of a representative exopolysaccharide revealed a →3)-β-D-Galp-(1→4)-β-D-Glcp-(1→ glycosidic linkage. This linear structure closely resembles bacterial xanthan, while the branched chain structure bears similarities to algal EPSs. Our findings highlight the collaborative synthesis of acidic EPSs by both microalgae and bacteria, emphasizing their joint contribution in the production of macromolecules within microalgal-bacterial symbiosis. This collaborative synthesis underscores the intricate molecular interactions contributing to the stability and function of these symbiotic relationships.
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•The exopolysaccharides from microalgal-bacterial symbioses were first studied.•The compositions and characteristics of the exopolysaccharides were analyzed.•The primary structure of a typical acidic exopolysaccharide was determined.•The synergy of algae and bacteria can be reflected by exopolysaccharides.
In this study, four sulfated fucans different in primary structures (sulfation patterns and the presence of branch) were obtained from different sea cucumbers and hydrolyzed to a similar molecular ...weight level (1100 kDa) by using a heterologously overexpressed fucanase. The influence of the primary structure of sulfated fucan on the multilayer emulsion-fabricating function was investigated. Results showed that the sulfation patterns had limited influence on the multilayer emulsion-fabricating function of sulfated fucan. All examined sulfated fucans could electrostatically adsorb to the surfaces of caseinate-coated droplets from pH 5 to 3, regardless of the primary structures. The sulfated fucans with a linear structure saturated the droplet surfaces at a lower concentration compared with the sulfated fucan with a branched structure. However, the multilayer emulsions fabricated from branched sulfated fucan were more resistant to NaCl stress (100 mM) than the emulsions fabricated from linear fucan. Furthermore, the fastest digestion rate and highest digestion extent were found in the multilayer emulsion fabricated by branched fucan. These results established the structure-function relationships between the primary structures and multilayer emulsion-fabricating function of sulfated fucan.
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•Effect of primary structure of fucan on multilayer emulsion was studied.•Sulfated fucans with similar molar mass but different primary structures were used.•Heterologously overexpressed fucanase was used to tailor molar mass.•Branched structure significantly impacted the performance of multilayer emulsion.•Limited impact of sulfation pattern on the multilayer emulsion was found.
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