International Journal of Biological Macromolecules最新文献

D-allulose, a low-calorie functional sweetener, is produced by the enzymatic conversion of d-fructose via D-allulose 3-epimerase (DAE) and holds significant market potential, particularly for individuals with obesity and diabetes. However, the limited reusability and stability of DAE have restricted its industrial application. In this study, we developed functional superparamagnetic supports by integrating diatomite, a biomineralized silica-based material, with cobalt ferrite nanoparticles through a green chemical co-precipitation method. The covalent attachment of DAE enzymes to these magnetic supports resulted in enzyme-metal hybrid catalysts (DAE@mDE-NH₂) that exhibited enhanced stability and facilitated recovery and reuse via magnetic separation. These catalysts showed superior stability in acidic conditions and high temperatures, with a 24-fold increase in half-life at 60 °C compared to free DAE. They also exhibited remarkable durability, retaining 95.36 % of their activity after six months of storage at 4 °C and 70.08 % activity after 12 consecutive cycles. Utilizing this robust and recyclable biocatalyst, 147.7 g/L of D-allulose was obtained from 500 g/L of d-fructose. This study presents a sustainable strategy for advancing the production of high-value functional sweeteners like D-allulose while providing new insights into enzyme immobilization for biocatalytic processes.

Enzymatic PET recycling has emerged as a promising green solution in addition to mechanical recycling, but low soluble expression levels of the inherently hydrophobic PET hydrolases hinder large-scale applications. Here, we propose a novel strategy for enhanced production of FastPETase in Escherichia coli using co-expression of molecular chaperones from Ideonella sakaiensis. Co-expression of cognate DnaK and DnaJ chaperones significantly increased soluble FastPETase expression (up to 2.5-fold), surpassing commercial chaperone plasmids. Furthermore, a combinatorial approach employing co-expression of DnaK/DnaJ chaperones and fusion of FastPETase with the VNp6-tag significantly boosted FastPETase secretion, yielding over 2 g/L of target protein in a 5-l bioreactor. Notably, the crude FastPETase in fermentation broth displayed comparable PET hydrolysis effects to the purified enzyme. This work not only provides new insights into the process of chaperones in protein folding but also suggests a novel and efficient strategy for producing recombinant proteins.

The CRISPR/Cas13 system has garnered attention as a potential tool for RNA editing. However, the degree of collateral activity among various Cas13 orthologs and their cytotoxic effects in mammalian cells remain contentious, potentially impacting their applications. In this study, we observed differential collateral activities for LwaCas13a and RfxCas13d in 293 T and U87 cells by applying both sensitive dual-fluorescence (mRuby/GFP) reporter and quantifiable dual-luciferase (Fluc/Rluc) reporter, with LwaCas13a displaying notable activity contrary to previous reports. However, significant collateral RNA cleavage exerted only a modest impact on cell viability. Furthermore, collateral activity of LwaCas13a mildly impeded, but did not arrest, porcine embryo development. Our findings reveal that distinct collateral RNA cleavage by Cas13 slightly suppresses mammalian cell proliferation and embryo development. This could account for the lack of reported collateral effects in numerous prior studies and offers new insights into the implications of the collateral activity of Cas13 for clinical application.

A novel fibrinolytic enzyme, from the marine fungus Penicillium steckii KU1, was purified to electrophoretic homogeneity. The fibrinolytic protease was purified to 13.56 times with a specific activity of 57.64 U/mg and final yield of 13.93 %. It was found to be a monomeric protein of 12.6 kDa, having optimum activity at 30 °C and pH 8.0. It is a plasmin-like enzyme, showing resemblance to ATP-dependent zinc metalloprotease with isoelectric point (pI) 8.0. Its activity is enhanced by Zn²⁺, and inhibited by ethylenediaminetetraacetic acid (EDTA), Co²⁺ and Fe²⁺. The enzyme interaction with substrate azocasein was endothermic and with inhibitor EDTA exothermic. The K_m, V_max, K_cat and catalytic efficiency of the enzyme for azocasein were determined to be 142.71 μg mL^-1, 285.71 μg min^-1 mL^-1, 6.35 S^-1 and 4.45 × 10^-2 S^-1 μg^-1 mL respectively. It hydrolyzed all three chains of fibrinogen within 9 h, and dissolved fibrin completely within 24 h. 2 mg/mL enzyme could dissolve blood clot completely within 30 min, with negligible hemolysis (2.60 %). Lowering the immunogenicity by the application of natural or engineered small proteins is a strategy to enhance the safety and efficacy of thrombolytic therapy. Hence, the present 12.6 kDa, plasmin-like fibrinolytic enzyme appears worthy of further investigations towards a thrombolytic therapeutic.

Osteoarthritis (OA) is a widespread joint disorder that is primarily noted for the progressive degeneration of joint cartilage, accompanied by a significant inflammatory response. Recently, there has been a growing interest in understanding the roles of ATF3 and ferritin-related RNAs in the context of immune responses and inflammatory processes. However, their specific functions and mechanisms in the progression of osteoarthritis have remained largely ambiguous and underexplored. The primary objective of this study was to thoroughly investigate the changes in expression levels of ATF3 and ferritin-related RNAs within osteoarthritic tissues, as well as to examine their potential effects on immune cell infiltration. To achieve this, advanced RNA sequencing technology was employed to meticulously analyze the expression levels of ATF3 and the ferritin-related RNAs. Furthermore, bioinformatics methods were utilized to assess the infiltration patterns of various immune cells and to explore the correlation between these infiltration patterns and the expression levels of RNA. The findings from this study revealed that both ATF3 and ferritin-related RNAs exhibited significantly elevated expression levels in tissues affected by osteoarthritis. Additionally, the immunoinfiltration analysis highlighted a positive correlation between the degree of infiltration of T cells and macrophages and the levels of ferritin-related RNAs. Such findings suggest that the presence of these immune cells is intricately linked to the expression of ferritin-associated RNAs. Further investigations indicated that ferritin-associated RNAs play a critical role in the progression of osteoarthritis by modulating inflammatory responses and influencing the activity of various immune cells. Consequently, both ATF3 and ferritin-related RNAs demonstrate abnormal expression patterns in osteoarthritis, which are closely associated with the infiltration of immune cells.

A novel carboxymethyl cellulose (CMC) graft copolymer (CMC-g-PSMAS) was successfully synthesized by grafting sodium methacrylate sulfonate (SMAS) onto CMC. The resulting CMC-g-PSMAS was used to absorb 1-allyl-3-methylimidazole chloride ([Amim]Cl) ionic liquid. The effects of different experimental factors such as monomer dosage, temperature and time on the grafting yield were systematically studied. Adsorption studies demonstrated that the adsorption equilibrium could be achieved within 60 min. The theoretical maximum adsorption capacity of CMC-g-PSMAS for [Amim]Cl reached 69.2 mg·g^-1. Compared to several kinetic and isothermal models, the adsorption process of [Amim]Cl onto CMC-g-PSMAS could be well-described by the pseudo-second-order model (R² = 0.991) and the Langmuir model (R² = 0.999), which was a typical chemical adsorption process. Adsorption thermodynamics analyses at 25 °C revealed that the adsorption process was spontaneous (ΔG = -33.37 KJ·mol^-1) and exothermic (ΔH = -56.52 KJ·mol^-1). The adsorption capacity of CMC-g-PSMAS was 35.3 mg·g^-1 after eight cycles, indicating its good stability and recyclability. As a consequence, CMC-g-PSMAS was efficient in the adsorption of [Amim]Cl, which could be a potential candidate for removing ionic liquids in aqueous environments.

The limited adsorption capability of chickpea protein isolates (CPI) at the oil-water interface restricts its application in emulsions. This study aimed to improve the emulsifying properties and interfacial behaviors of CPI through Maillard reaction with citrus pectin (CP). The research findings showed that the covalent linking of CP with CPI caused the unfolding of the molecular structure of CPI, exposing more hydrophobic groups. Consequently, the CPI-CP conjugates exhibited improved emulsifying properties. Emulsions stabilized by CPI-CP conjugates after 12 h of glycosylation demonstrated the smallest droplet sizes (1.73 μm) and the highest negative zeta potentials (-54.7 mV). Glycosylation also improved the storage and environmental stability of these emulsions. Interfacial adsorption kinetics analysis revealed the lower interfacial tension (13.94 mN/m) and faster diffusion rates of the CPI-CP conjugates. Furthermore, interfacial dilatational rheology analysis indicated that the CPI-CP conjugates formed an interfacial layer with a higher viscoelastic modulus (33.214 mN/m) and predominant elastic behavior. The interfacial film of CPI-CP conjugates showed excellent resistance to amplitude and frequency variations, enhancing emulsion stability. Thus, this study demonstrates that moderate glycosylation enhances interfacial performances and improves emulsion stability of CPI, providing new insights into the mechanisms by which CPI stabilizes emulsions.

Up to now, the clinical treatment of spinal cord injury (SCI) to recover the locomotion function, sensory function, and autonomic function of patients is a global medical challenge. In this study, based on the excellent effects of Tetramethylpyrazine (TMP) on regulating pathological micro-environment, we designed a new injectable conductive hydrogel consists of water-soluble polypyrrole (Ppy), agar, and TMP. The TMP@PA hydrogel has excellent physicochemical properties, bio-safety, and drug release ability, which can be injected into lesions in situ without secondary injury for SCI. Our in vivo and in vitro experiments have demonstrated that the TMP@PA hydrogel can not only fill the spinal cord cavity to reconstruct the electrical conduction pathway but also release TMP continuously to inhibit ferroptosis by regulating nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy regulated by Yes-Associated Protein (YAP) to promote SCI repair. Collectively, TMP@PA hydrogel may be an effective tissue engineering scaffold to treat SCI with highly promising clinical applications.

Uric acid, urea, and other metabolites in urine after exercise often reflect chronic injury syndrome in athletes. However, traditional urine detection methods have issues such as high costs and low detection sensitivity. SERS can rapidly, continuously, and sensitively monitor metabolites in human urine. In this research, a combined SERS substrate (CMBCM@Ag NPs@PGA) was developed based on the carboxymethyl modification of the bacterial cellulose membrane (BCM) surface. The numerous carboxyl groups on the CMBCM surface made it easier for silver ions to be adsorbed, leading to their conversion into silver nanoparticles (Ag NPs) when a reducing agent was introduced. This process allowed the nanoparticles to firmly adhere to the CMBCM surface, forming a uniform and stable "hot spot." "The CMBCM@Ag NPs@PGA substrate maintains excellent stability and sensitivity in the assay." It can detect very small amounts of urea and uric acid in urine with high sensitivity, with LOD of 1.05 μM for urea and 0.0075 μM for uric acid. Additionally, it exhibits good stability, antibacterial properties, and cell compatibility. In addition, the substrate can be used as a sensor to monitor pH in real-time. This expands the use of cellulose in flexible SERS sensing and detecting human exercise metabolic health.