International Journal of Biological Macromolecules最新文献

Endo-β-1,3-glucanase (β-1,3-GA) is a key enzyme capable of acting on the β-1,3-glycosidic bond of β-1,3-glucan, resulting in the production of β-1,3-gluco-oligosaccharides with higher water solubility. Higher temperatures are beneficial for curdlan hydrolysis; however, low enzymatic activity and thermal stability limit their applicability. In this study, a mutant library of Endo-β-1,3-glucanase (AC-GA) derived from Alkalihalobacillus clausii KSM-K16 was constructed by a semi-rational design using amino-acid-based multiple sequence alignment and protein structure-based computer-aided engineering. The best combination mutant (S52T/M120L) was screened through ordered recombination mutations, which showed a 24.88 % increase in specific enzyme activity over the wild-type. The melting temperature (Tm) value, an enzyme protein denaturation temperature, was raised to 82.99 °C from 78.60 of the wild type. In comparison, the K_m for hydrolysis of curdlan by S52T/M120L was reduced by 12.1 %, while the k_cat was increased by 59.39 %, thus leading to a higher catalytic efficiency (k_cat/K_m, 227.73 vs 125.46 mL·s^-1·mg^-1). Molecular dynamics (MD) simulations showed that mutations resulted in a reduction in the overall flexibility of the enzyme, an increase in rigidity, and a more stable structure. An increase in the hydrophobic network at the entrance of the substrate increases the accessibility of the substrate to the enzyme, resulting in increased enzyme activity. High-efficiency mutants have potential industrial applications in the enzymatic preparation of β-1,3-gluco-oligosaccharides.

This study aims to improve the properties of polyether sulfone (PES) membranes by using an innovative composite filler. Pistachio shell-derived activated carbon (PSAC) was initially synthesized via chemical activation, followed by surface modification with ZIF-8 and ZIF-67. Subsequently, modified membranes with varying weight percentages of this composite were fabricated using the phase inversion method. The PSAC@ZIF-8&ZIF-67/PES membranes were characterized through FESEM, AFM, pore size, zeta potential, porosity, and water contact angle analyses. The incorporation of the composite in the membranes was confirmed through ATR-FTIR, XRD, and EDS mapping analyses. The finding indicated that adding 0.6 wt% of nanoparticles improved membrane hydrophilicity, increased surface charge, and enhanced porosity. Additionally, the mixed membranes exhibited reduced sedimentation and higher dye removal than unmodified membranes. The optimum amount of composite is determined as 0.6 wt%. At this condition, pure water flux (PWF) increased dramatically from 22.56 L/m²h to 96.26 L/m²h. The mixed matrix membrane demonstrated superior efficiency in removing malachite green (MG) (97 %) and crystal violet (CV) dyes (93 %) and achieved the highest recovery ratio of 61.9 %, indicating a more remarkable membrane ability to combat fouling. The developed membrane demonstrated enhanced hydrophilicity, dye removal efficiency, and antifouling properties, making it promising for environmental applications.

This study examined the rheological properties, interfacial characteristics, particle size, zeta potential, Turbiscan stability index (TSI), morphology, and encapsulation efficiency of curcumin (Cur) loaded fish gelatin (FG) emulsions modified with γ-polyglutamic acid (γ-PGA). The results showed that adding γ-PGA significantly increased curcumin encapsulation efficiency. At 0.3 mg/mL, FG emulsions had an encapsulation efficiency of 80.14 %, while FG-γ-PGA emulsions reached 90.35 %. The FG-γ-PGA emulsions also showed enhanced stability and resistance to phase separation, remaining stable for seven days, compared to three days for FG emulsions. After 24 h, the TSI of FG emulsions with 0.6 mg/mL Cur was 2.46, significantly higher than the 0.55 TSI for FG-γ-PGA emulsions at the same concentration. FG-γ-PGA emulsions had smaller droplet sizes, and analysis of interfacial characteristics, particle size, and zeta potential indicated better system stability than FG emulsions. These improved properties of FG-γ-PGA emulsions highlight their potential as efficient carriers for curcumin. Overall, the favorable characteristics of FG-γ-PGA emulsions suggest promising applications in the food industry, especially for developing functional foods with extended shelf life and enhanced nutritional benefits.

Sediment from the effluent of cotton spinning industry was valorized as the renewable bio-based polyols substitute for the rigid polyurethane (RPUFs), targeting to generate the economic and environmental benefits. Before reaction with the isocyanate, the sediment was functionalized by hydroxymethylation, in order to increase the density of the active hydroxyl groups for higher reactivity. The structural characterization results of the functionalized sediment indicated the material exhibited narrow molecular weight distribution, high hydroxyl groups content, and highly aromatic skeleton, which can be qualified as the renewable polyols for the RPUFs. In the crosslinking process, the effect of the polyols substitute rate of the sediments on the physio-chemical properties and the thermo-resistant performances of the resulting RPUFs was investigated. Specifically, in the group with 30 wt% of polyols substitution, the received foam exhibited comprehensive superiorities in compressive strength (0.58 MPa), apparent density (58 kg m^-3), and thermo-conductivity (0.032 W m^-1 K^-1). Attractively, the RPUFs also exhibited good flame retardancy. The burning time can be extended by 30 % compared to the control group that without the sediment's substitution. Moreover, the RPUF also possessed good degradability, allowing for harmless recycling. The current work provided a potential route for the valorization of the hazardous waste effluent from the cotton spinning industry.

In the present research, we investigate Congo red (CR) removal by layered double hydroxide and oxide AlCa on cellulose acetate (CA) fiber as anion-adsorbents in aqueous solution. The as-prepared composite was characterized by FE-SEM, XRD, FTIR, EDS-mapping and BET-BJH analyses. The CR adsorption ability on AlCa LDH/CA and AlCa LDO/CA adsorbents was evaluated. The removal property, dye adsorption and filtration properties of the AlCa LDO/CA composite were studied for removal CR based on central composite design (CCD) technique through investigating operational variables (temperature, adsorbent dosage, pH and contact time). The fabricated AlCa LDO/CA composite indicates a high removal efficiency up to 98.7 % for the CR removal in the 16 min. The data of the adsorption equilibrium were described by the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms, and exhibited that AlCa LDH/CA fibers and AlCa LDO/CA fibers followed a pseudo-second-order kinetic model and Langmuir isotherm. The stability of Al-Ca-LDO/CA fibers nanocomposite was indicated that it was >95 % after eight cycles for removal of CR in the batch method on stirrer. The findings illustrated that appropriate AlCa LDO/CA fiber could be an efficient technique for CR elimination.

The extraction of polysaccharides from stem barks and flowers of Magnolia officinalis were optimized using response surface methodology and the maximum yields were 4.12 ± 0.06 % and 5.5 ± 0.08 %, respectively. Three homogeneous polysaccharides including MOBP-I, MOBP-II and MOFP-I were further purified and their compositional characterization were compared. Molecular weights of MOBP-I, MOBP-II and MOFP-I were 5.9 × 10³, 6.8 × 10³ and 3.9 × 10⁴ Da, respectively. Gas chromatography (GC) analysis suggested that MOBP-I, MOBP-II and MOFP-I were composed of rhamnose, arabinose, mannose, glucose and galactose at different ratios and exhibited different appearance and glycosidic linkages. MOFP-I but not MOBP-I and MOBP-II had three helix structures. MOBP-I, MOBP-II and MOFP-I showed significant hypoglycemic and photoprotection capacities with different efficacy. MOBP-I had greater hypoglycemic activity, as evidenced by the increased α-glucosidase inhibition activity and glucose consumption in insulin-resistant HepG2 cells. MOBP-II and MOFP-I were more powerful in reversing ultraviolet-B (UVB)-irradiated photoaging of HaCaT cells. The difference of polysaccharides compositions might explain for their bioactivity discrepancy.

Algal enzymes are essential catalysts in numerous biological reactions and industrial processes owing to their adaptability and potency. The marketing of algal enzymes has recently risen due to various reasons, including the cost-efficient manner of their cultivation in photobioreactors, the eco-friendly production of high biomass contents, sources of novel enzymes that used in many sectors (biofuel and bioremediation applications), sustainability, and more renewability. Oxidoreductases and hydrolytic enzymes are among the important applied algal enzymes in industrial applications, with annually growing demand. These algal enzymes have opened up new avenues for significant health advantages in reducing and treating oxidative stress, cardiovascular illness, tumors, microbial infections, and viral outbreaks. Despite their promising uses, commercial applications of algal enzymes face many difficulties, such as stability, toxicity, and lower data availability on specific and adequate catalytic mechanisms. Therefore, this review focuses on the algal enzyme types, their uses and advantages over other microbial enzymes, downstream and upstream processing, their commercial and marketing, and their challenges. With the constant development of novel enzymes and their uses, enzyme technology provides exciting options for several industrial sectors.

Selenium nanoparticles (Se NPs) have gained growing significance due to their remarkable therapeutic qualities, decreased toxicity, enhanced bioavailability, and biocompatibility compared to other selenium compounds. Se NPs were synthesized using ascorbic acid (AA) and carboxymethyl cellulose (CMC) as reducing and capping agents, respectively. This was carried out by optimizing the physiochemical preparation parameters (e.g., precursor salt concentration, AA concentration, temperature, and pH). Characterization of the optimized Se/CMC nanocomposite sample was conducted using several techniques including UV-Vis spectroscopy, FT-IR, X-ray XRD, TEM, SEM, EDX, DLS, and Zeta potential. The UV-Vis spectra results indicate that the synthesized Se/CMC nanocomposite exhibits a most prominent surface plasmon resonance (SPR) peak at λ_max = 270 nm. The diameter of the synthesized Se/CMC nanocomposite varied between 100 and 500 nm as observed in TEM images, and as verified by the DLS technique. Moreover, the Z-potential evaluated for the Se/CMC nanocomposite using the most optimal synthesis conditions was -21.8 ± 4.48 mV. The results obtained showed that Se/CMC nanocomposite had a more significant impact on Gram-negative clinical bacterial isolates (23 ± 0.97 mm) than Gram-positive (22 ± 0.95 mm). Additionally, the synthesized nanocomposite showed a highly antioxidant activity (83 %) of inhibition DPPH free radicals results using DPPH assay. Also, the fabricated Se/CMC nanocomposite has good anticancer activity (168 μg/mL) against the liver HepG2 cell line using MTT assay. Hence, the Se/CMC nanocomposite that was prepared has promising prospects in the field of healthcare owing to its enhanced capacity as an antioxidant, anticancer, and antibacterial agent.

Oxidative stress caused by hypoxia can lead to serious bodily damage and functional degradation. Our previous study in pigs showed that the insulin-like growth factor II receptor (IGF2R) gene might participate in the process of hypoxia adaptability. To investigate the function and mechanism of IGF2R in cellular hypoxia tolerance, we analyze the effect of IGF2R on cell survival capacity under hypoxia conditions in intestinal porcine enterocyte cell line (IPEC-J2) cells. The results show that under hypoxia condition (3% O2), cell viability is significantly reduced, the expression of IGF2R and cell apoptosis are significantly increased. Functional analysis suggests that suppressing IGF2R expression under hypoxia does not affect cell cycle and cell proliferation but increases cellular viability. Meanwhile, the expression of the pro-apoptotic gene BAX is reduced, the hypoxia-induced apoptosis is rescued, and cell survival is significantly improved. Transcriptome analysis suggests that global gene expression changes in knockdown IGF2R under hypoxia, IGF2R may regulate apoptosis through oxidative phosphorylation. Our results demonstrate that suppressing IGF2R expression under hypoxia can rescue hypoxia-induced cell injury by reducing the expression of BAX, highlighting the potential ability of IGF2R regulation for the treatment of hypoxia stress.