摘要：
Lotus root is a widely popular aquatic vegetable with edible and medicinal values. Here we report the structure and lipid-lowering activity of two lotus root polysaccharides LRW (lotus root polysaccharide by water extraction) and LRA (lotus root polysaccharide by alkali extraction), that were extracted by aqueous and alkaline solution respectively. The results showed that the yield of polysaccharide from lotus root could be significantly improved by alkali extraction. Basic composition and structural characterization showed that the total sugar contents of LRW and LRA were 96.83 % and 73.66 %, and the molecular weights were 2.464 × 10 5 Da and 1.727 × 10 5 Da, respectively. LRW and LRA had the similar structure that the main backbone consisted of →4)-α-D-Glcp-(1→ with branches at C-6 site. Both LRW and LRA could scavenge DPPH and hydroxyl radicals effectively, and have strong adsorption capacity to cholate salts in a concentration-dependent manner. In HepG2 cells, LRW and LRA inhibited the accumulation of lipid droplets induced by oleic acid, and increased the activity of T-SOD and CAT, meanwhile, reduced the level of MDA, TC and TG, showing good lipid-lowering activity. In comparison, the lipid-lowering effect of LRA was better than that of LRW. In addition, gene sequencing and RT-PCR showed that AMPK, ACC, PPARα and CPT-1 were essential for LRA to exert a lipid-lowering effect. This study provides a theoretical basis for the extraction and lipid-lowering application of lotus root polysaccharides.
Lotus root is a widely popular aquatic vegetable with edible and medicinal values. Here we report the structure and lipid-lowering activity of two lotus root polysaccharides LRW (lotus root polysaccharide by water extraction) and LRA (lotus root polysaccharide by alkali extraction), that were extracted by aqueous and alkaline solution respectively. The results showed that the yield of polysaccharide from lotus root could be significantly improved by alkali extraction. Basic composition and structural characterization showed that the total sugar contents of LRW and LRA were 96.83 % and 73.66 %, and the molecular weights were 2.464 × 10 5 Da and 1.727 × 10 5 Da, respectively. LRW and LRA had the similar structure that the main backbone consisted of →4)-α-D-Glcp-(1→ with branches at C-6 site. Both LRW and LRA could scavenge DPPH and hydroxyl radicals effectively, and have strong adsorption capacity to cholate salts in a concentration-dependent manner. In HepG2 cells, LRW and LRA inhibited the accumulation of lipid droplets induced by oleic acid, and increased the activity of T-SOD and CAT, meanwhile, reduced the level of MDA, TC and TG, showing good lipid-lowering activity. In comparison, the lipid-lowering effect of LRA was better than that of LRW. In addition, gene sequencing and RT-PCR showed that AMPK, ACC, PPARα and CPT-1 were essential for LRA to exert a lipid-lowering effect. This study provides a theoretical basis for the extraction and lipid-lowering application of lotus root polysaccharides.
通讯机构：
[Guo, DJ ] W;Wuhan Polytech Univ, Coll Food Sci & Engn, Wuhan 430040, Peoples R China.
关键词：
carbonyls;fatty acids;sous vide;TBARS
摘要：
The laws and interrelationships of lipid and protein oxidation in duck meat during sous vide cooking (SVC) are still unclear. In this study, the oxidation mechanisms of the muscle of duck legs during SVC were investigated from the aspects of fatty acid (FA) profile, antioxidant system activity, enzyme activity, and iron element. Lipid oxidation predominantly occurred within the initial 0-2 h of the SVC process, during which the Thiobarbituric acid reactive substances (TBARS) value escalated to 10-fold of its initial level. Protein oxidation was mainly observed between 0 and 4 h, with the carbonyl content increasing by 23.3%. The FAs profile underwent changes primarily within the initial 0-2 h, and then their proportions continued to evolve in a manner that was favorable for oxidative stability. Following 4 h of SVC, the scavenging rates of <middle dot>OH and DPPH<middle dot> free radicals decreased to the lowest, decreasing by 92.9% and 45.6%. As cooking time increased, lipoxygenase activity increased by more than six times, while Total superoxide dismutase (T-SOD) and GSH-Px activity decreased by 31.7% and 75.2%, respectively. The heme iron content was decreased by 26.1% after 8 h of SV treatment. These data can provide a theoretical foundation for optimizing parameters of the SVC process and improving the oxidative stability of SVC meat products.
摘要：
Ferritin heavy chain 1 (FTH1) is a key iron-storage protein that regulates iron availability, supports immune defense, and prevents iron-induced toxicity. During Mycobacterium tuberculosis (Mtb) infection, macrophages enhance FTH1 expression to sequestrate iron and limit Mtb growth. However, Mtb can exploit the host ferritinophagy pathway to degrade FTH1 and release iron, thereby promoting its survival. Although FTH1 plays an essential role in host-pathogen interaction during Mtb infection, its regulation remains unclear. Previous studies suggest that post-transcriptional mechanism, particularly alternative polyadenylation (APA), are critical in immune responses. We propose that APA, which determines the length of a transcript's 3'UTR, may regulate FTH1 expression during Mtb infection. Our study demonstrates that Mtb induces APA of FTH1 in macrophages, favoring the production of longer isoforms that enhance protein synthesis. Mechanistically, Mtb disrupts the interaction between NUDT21 and CPSF6, impairing NUDT21's ability to bind UGUA motifs in the FTH1 3'UTR, a key step in polyadenylation site selection. Silencing NUDT21 reduces macrophage bactericidal activity against Mtb, highlighting its role in immune defense. These findings reveal a novel Mtb-driven mechanism that enhances FTH1 expression via the NUDT21-mediated APA pathway in macrophages, suggesting that Mtb manipulates this process to promote its survival. This study provides new insights into tuberculosis pathogenesis and points to potential avenues for therapeutic exploration.
摘要：
Previous studies have demonstrated corilagin’s inhibitory effects on the growth of various cancer cells. Given the limited research on corilagin’s impact on ovarian cancer, a particularly deadly gynecological malignancy, this study aimed to investigate corilagin’s influence on A2780 ovarian cancer cell apoptosis and its underlying mechanisms. The goal was to evaluate corilagin’s potential as a therapeutic agent for ovarian cancer. The results of the CCK-8 assay showed that corilagin inhibited the proliferation of A2780 ovarian cancer cells while exhibiting lower toxicity to normal ovarian surface epithelial cells (IOSE-80). We found that corilagin significantly altered the A2780 cell cycle, decreasing the proportion of cells in the G0/G1 and G2/M phases and inducing cell cycle arrest in the S phase. At low concentrations, corilagin induced apoptosis in A2780 cells, accompanied by a decline in mitochondrial membrane potential and calcium influx. Transcriptome sequencing analysis identified differentially expressed apoptosis-related genes in corilagin-treated A2780 cells, primarily within the PI3K-AKT pathway. Furthermore, qPCR and Western blot results confirmed the upregulation of p53 and Bax genes and the downregulation of BCL-2. Corilagin also increased the expression of apoptotic factors caspase-9, caspase-3, PUMA, and cytochrome C, indicating its ability to induce apoptosis. Overall, corilagin effectively inhibited A2780 cell proliferation, induced cell cycle arrest, and triggered apoptosis. Its anti-tumor effect in vitro suggests its potential as a therapeutic agent for ovarian cancer A2780, especially through the PI3K/p53 pathway.
通讯机构：
[Yang, JK ; Han, ZG] W;Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430023, Peoples R China.
关键词：
glycoside hydrolase family 10;low-temperature enzymes;molecular dynamics simulation;xylanases
摘要：
This study investigates the biochemical properties of two xylanases, ZgXyn10A and CaXyn10B, which are members of the glycoside hydrolase family 10 (GH10) and originate from the marine Bacteroidetes species Zobellia galactanivorans and Cellulophaga algicola, respectively. Utilizing an auto-induction expression system in Escherichia coli, high-purity recombinant forms of these enzymes were successfully produced. Biochemical assays revealed that ZgXyn10A and CaXyn10B exhibit optimal activities at 40 degrees C and 30 degrees C, respectively, and demonstrate a high sensitivity to temperature fluctuations. Unlike conventional low-temperature enzymes, these xylanases retain only a fraction of their maximal activity at lower temperatures. To gain deeper insights into the structural and functional properties of these marine xylanases, two thermostable GH10 xylanases, TmxB and CoXyn10A, which share comparable amino acid sequence identity with ZgXyn10A and CaXyn10B, were selected for structural comparison. All four marine xylanases share a nearly similar three-dimensional structural topology. Molecular dynamics simulation indicated a striking difference in structural fluctuations between the low-temperature and thermostable xylanases, as evidenced by the distinct root mean square deviation values. Moreover, root mean square fluctuation analysis specifically identified the beta 3-alpha 3 and beta 7-alpha 7 loop regions within the substrate-binding cleft as crucial determinants of the temperature characteristics of these GH10 xylanases. Our findings establish loop dynamics as a key evolutionary driver in the thermal adaptation of GH10 xylanases and propose a loop engineering strategy for the development of industrial biocatalysts with tailored temperature responses, particularly for lignocellulosic biomass processing under moderate thermal conditions.
摘要：
The aprBP gene from Bacillus patagoniensis DB-5, encoding a 378-amino-acid alkaline protease, was cloned and expressed in Escherichia coli. The amino acid sequence of APrBP showed 62.8-84.4% identity with the S8 peptidase subtilisin family alkaline proteases reported in the literature. Recombinant APrBP was purified using Ni-NTA affinity chromatography with 45.61% recovery and a homogeneous band was detected at approximately 38 kDa on the SDS-PAGE gel. The optimum temperature of APrBP was 60°C. The presence of 2 mM Ca(2+) significantly enhanced the optimal temperature and thermostability. The enzyme demonstrated optimum activity at pH 12 and maintained high stability at pH 8.0-11.0. Protease activity was stimulated by Mn(2+), Ca(2+), Mg(2+), Ni(2+), TritonX-100, Tween-20 and Tween-80, while completely inactivated by PMSF, EDTA and Cu(2+). The APrBP exhibited good tolerance to oxidizing and reducing agents. Notably, the protease exhibited remarkable stability in 50% (v/v) concentrations of several organic solvents, such as methanol, acetone, glycerol, dimethyl sulfoxide, n-hexane, and ethyl acetate. The APrBP efficiently hydrolyzed natural proteins, demonstrating the highest catalytic efficiency for casein, excellent hydrolysis activity for bovine serum albumin, hemoglobin, and keratin, and favorable hydrolysis ability for whey proteins. Moreover, molecular docking results revealed stable interactions between APrBP and casein, hemoglobin, whey proteins and keratin. This study indicated that APrBP has some useful properties and explored its potential as a bio-additive detergent as well as in utilizing feather waste and whey protein.
摘要：
Objectives The persistence and infectivity of respiratory viruses in cadavers remain poorly characterized, posing significant biosafety risks for forensic and healthcare professionals. This study systematically evaluates the post-mortem stability and transmission potential of SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV) under varying environmental conditions, providing critical insights into viral kinetics.
The persistence and infectivity of respiratory viruses in cadavers remain poorly characterized, posing significant biosafety risks for forensic and healthcare professionals. This study systematically evaluates the post-mortem stability and transmission potential of SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV) under varying environmental conditions, providing critical insights into viral kinetics.
Methods To assess the post-mortem stability of SARS-CoV-2, tissue samples were collected from infected cadavers at 4℃, room temperature (RT, 20-22℃), and 37℃ over a predetermined timeframe. Viral kinetics were analyzed using quantitative assays, while histopathology and immunohistochemistry characterized tissue-specific distribution. Additionally, comparative analyses were conducted both in vitro and in cadaveric tissues to characterize the survival dynamics of IAV and RSV under identical conditions.
To assess the post-mortem stability of SARS-CoV-2, tissue samples were collected from infected cadavers at 4℃, room temperature (RT, 20-22℃), and 37℃ over a predetermined timeframe. Viral kinetics were analyzed using quantitative assays, while histopathology and immunohistochemistry characterized tissue-specific distribution. Additionally, comparative analyses were conducted both in vitro and in cadaveric tissues to characterize the survival dynamics of IAV and RSV under identical conditions.
Results SARS-CoV-2 exhibited prolonged post-mortem infectivity, persisting for up to 5 days at RT and 37℃ and over 7 days at 4℃, with the highest risk of transmission occurring within the first 72 hours at RT and 24 hours at 37℃. In contrast, RSV remained viable for 1-2 days, while IAV persisted for only a few hours post-mortem. Viral decay rates were temperature-dependent and varied across tissues, demonstrating distinct post-mortem survival kinetics.
SARS-CoV-2 exhibited prolonged post-mortem infectivity, persisting for up to 5 days at RT and 37℃ and over 7 days at 4℃, with the highest risk of transmission occurring within the first 72 hours at RT and 24 hours at 37℃. In contrast, RSV remained viable for 1-2 days, while IAV persisted for only a few hours post-mortem. Viral decay rates were temperature-dependent and varied across tissues, demonstrating distinct post-mortem survival kinetics.
Conclusions This study presents the first comprehensive analysis of viral persistence in cadavers, revealing prolonged SARS-CoV-2 stability compared to IAV and RSV. These findings underscore the need for enhanced post-mortem biosafety protocols to mitigate occupational exposure risks in forensic and clinical settings. By elucidating viral decay dynamics across environmental conditions, this research establishes a critical foundation for infection control strategies, informing biosafety policies for emerging respiratory pathogens.
This study presents the first comprehensive analysis of viral persistence in cadavers, revealing prolonged SARS-CoV-2 stability compared to IAV and RSV. These findings underscore the need for enhanced post-mortem biosafety protocols to mitigate occupational exposure risks in forensic and clinical settings. By elucidating viral decay dynamics across environmental conditions, this research establishes a critical foundation for infection control strategies, informing biosafety policies for emerging respiratory pathogens.
Data availability All data are available in the main text or the supplementary materials .
All data are available in the main text or the supplementary materials .
摘要：
Background Proteins which are important biomarkers for disease diagnosis, prognosis and treatment are often present at very low concentrations in biological samples. Measuring these low-level proteins is important yet challenging. Conventional enzyme-linked immunoassays (ELISAs) usually lack the sensitive required. While ultrasensitive detection methods, such as digital ELISA have recently significantly advanced in sensitivity, they usually face high-cost of using paramagnetic beads or require complicated substrate fabrication, limiting their accessibility for large-scale screening or application in resource-limited settings. Therefore, there is a pressing need to develop cost-effective detection methods with ultrahigh sensitivity to accurately detecting low-level protein biomarkers.
Proteins which are important biomarkers for disease diagnosis, prognosis and treatment are often present at very low concentrations in biological samples. Measuring these low-level proteins is important yet challenging. Conventional enzyme-linked immunoassays (ELISAs) usually lack the sensitive required. While ultrasensitive detection methods, such as digital ELISA have recently significantly advanced in sensitivity, they usually face high-cost of using paramagnetic beads or require complicated substrate fabrication, limiting their accessibility for large-scale screening or application in resource-limited settings. Therefore, there is a pressing need to develop cost-effective detection methods with ultrahigh sensitivity to accurately detecting low-level protein biomarkers.
Results In the study, we developed a cost-effective and easily prepared PDMS microwell array platform for bead-free digital enzyme-linked immunoassay (ELISA) to achieve ultrasensitive protein detection. Both the immunocomplexes formation and separation process, which are two key steps in digital ELISA occur within the PDMS microwells, eliminating the need for paramagnetic beads and complex bead-separation systems. This approach significantly reduces detection costs compared to the widely used single-molecule arrays (SiMoAs)-based digital ELISA, which relies on large quantities of paramagnetic beads for immunocomplexes immobilization and intricate microwell array chips for immunocomplexes separation. Here, the PDMS microwell array chip was modified to generate large-scale femtoliter droplet arrays for single-molecule reactions, with minimized droplet evaporation and no cross-contamination. The PDMS microwell array platform was further successfully applied to single-molecule enzyme detection and cytokine analysis, achieving detection limits of 1.57 fM for streptavidin-β-galactosidase (SβG) and 12.3 fg/ml for human interleukin-6.
In the study, we developed a cost-effective and easily prepared PDMS microwell array platform for bead-free digital enzyme-linked immunoassay (ELISA) to achieve ultrasensitive protein detection. Both the immunocomplexes formation and separation process, which are two key steps in digital ELISA occur within the PDMS microwells, eliminating the need for paramagnetic beads and complex bead-separation systems. This approach significantly reduces detection costs compared to the widely used single-molecule arrays (SiMoAs)-based digital ELISA, which relies on large quantities of paramagnetic beads for immunocomplexes immobilization and intricate microwell array chips for immunocomplexes separation. Here, the PDMS microwell array chip was modified to generate large-scale femtoliter droplet arrays for single-molecule reactions, with minimized droplet evaporation and no cross-contamination. The PDMS microwell array platform was further successfully applied to single-molecule enzyme detection and cytokine analysis, achieving detection limits of 1.57 fM for streptavidin-β-galactosidase (SβG) and 12.3 fg/ml for human interleukin-6.
Significance A low-cost PDMS microwell array platform for digital ELISA was developed. The fabrication of PDMS microwell array chip was straightforward by soft lithography, enabling mass production with small batch-to-batch variation. With its cost-effective fabrication process and high detection sensitivity, the PDMS microwell array would be a promising platform for ultrasensitive protein detection, especially in the area of early disease screening.
A low-cost PDMS microwell array platform for digital ELISA was developed. The fabrication of PDMS microwell array chip was straightforward by soft lithography, enabling mass production with small batch-to-batch variation. With its cost-effective fabrication process and high detection sensitivity, the PDMS microwell array would be a promising platform for ultrasensitive protein detection, especially in the area of early disease screening.
摘要：
Cardiovascular complications are a primary focus in the clinical management of type 2 diabetes, as they are the leading causes of disability and mortality in individuals with diabetes. Insulin resistance and endothelial dysfunction commonly coexist in diabetic patients. An increasing body of research indicates a reciprocal and interconnected association between endothelial function and insulin resistance. Insulin resistance can manifest in two distinct forms: endothelial and metabolic, with the former predominantly affecting vascular endothelial cells and the latter primarily impacting peripheral cells. The understanding of endothelial insulin resistance is crucial in comprehending the pathophysiology of cardiovascular complications in type 2 diabetes. Hence, the objective of this study is to examine the correlations, interplays, and molecular pathways linking endothelial insulin resistance and metabolic insulin resistance, with the aim of offering novel insights and scholarly resources for the prevention and management of diabetic vascular complications.
作者机构：
[Yang, Jiangke; Wang, Shiqing; Zheng, Yanli; Deng, Yuhui; Hu, Ping; Lei, Lei] Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430023, Peoples R China.;[Chan, Zhuhua; Hu, Ping] Marine Biol Resources Dev & Utilizat Engn Technol, TIO, MNR, Xiamen 361005, Fujian, Peoples R China.;[Peng, Wenfang; Peng, WF; Xue, Qingxin; Li, Jiaxin] Hubei Univ, Hubei Engn Res Ctr Bioenzyme Catalysis, Environm Microbial Technol Ctr Hubei Prov, Sch Life Sci,State Key Lab Biocatalysis & Enzyme E, Wuhan 430062, Peoples R China.
通讯机构：
[Yang, JK ] W;[Peng, WF ] H;[Chan, ZH ] M;Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430023, Peoples R China.;Marine Biol Resources Dev & Utilizat Engn Technol, TIO, MNR, Xiamen 361005, Fujian, Peoples R China.
关键词：
CRISPR-Cas9;High-yield and industrial-scale;Kluyveromyces lactis;Precision strain engineering;Recombinant calf chymosin;Secretory production
摘要：
As an important industrial enzyme, chymosin has been widely used in cheese manufacturing. Fermentation with Kluyveromyces lactis has allowed recombinant chymosin production to fit the growing global demand for cheese consumption; yet improvements can be made to allow for stable and larger-scale production. In this work, various c hymosin p roducing (CP) strains were constructed via targeted chromosomal integration of various copies of a p rochymosin e xpression c assette (PEC) using a CRISPR-Cas9 platform optimized for K. lactis. It enabled the demonstration that chymosin yields could be increased along with gradual chromosomal accumulation of PEC inserts within up to 3 copies. Finally, an optimal CP3i strain was constructed, and with which high yields of recombinant chymosin were attained, reaching ca. 1,200 SU/mL in shake-flask fermentation and ca. 28,000 SU/mL in batch-mode bioreaction, respectively. The activity of the product in milk-curding was observed. These findings provide direction to apply K. lactis-based platforms in the subsequent industrial-scale production of recombinant chymosin.
As an important industrial enzyme, chymosin has been widely used in cheese manufacturing. Fermentation with Kluyveromyces lactis has allowed recombinant chymosin production to fit the growing global demand for cheese consumption; yet improvements can be made to allow for stable and larger-scale production. In this work, various c hymosin p roducing (CP) strains were constructed via targeted chromosomal integration of various copies of a p rochymosin e xpression c assette (PEC) using a CRISPR-Cas9 platform optimized for K. lactis. It enabled the demonstration that chymosin yields could be increased along with gradual chromosomal accumulation of PEC inserts within up to 3 copies. Finally, an optimal CP3i strain was constructed, and with which high yields of recombinant chymosin were attained, reaching ca. 1,200 SU/mL in shake-flask fermentation and ca. 28,000 SU/mL in batch-mode bioreaction, respectively. The activity of the product in milk-curding was observed. These findings provide direction to apply K. lactis-based platforms in the subsequent industrial-scale production of recombinant chymosin.
摘要：
BACKGROUND: Diseases are often caused by multiple factors, angiogenesis-related genes (ARGs) have been shown to be associated with cancer, however, their role in colon cancer had not been fully explored. This study investigated potential biomarkers based on ARGs to improve prognosis and treatment effect in colon cancer. METHODS: ARGs associated with colon cancer prognosis were identified using Cox regression analysis and LASSO analysis. Furthermore, a prognostic model was constructed in colon cancer based on the 3 ARGs, and its biological function were analyzed. We evaluated the differences in tumor immune microenvironment based on prognostic signature. Finally, cell experiments confirmed the function of genes in colon cancer. RESULTS: The prognostic value of ARGs in colon cancer patients has been comprehensively analyzed for the first time and identified 3 ARGs with prognostic values. A prognosis risk model was constructed based on 3 ARGs and its prognostic value was validated on an independent external colon cancer dataset. In colon cancer patients, this prognostic feature was an independent risk factor and was significantly correlated with clinical feature information of colon cancer patients. This feature was also related to the immune microenvironment of colon cancer. Cell experiments showed that high expression of TNF Receptor Superfamily Member 1B (TNFRSF1B) significantly promoted apoptosis and inhibited proliferation of colon cancer cells. Therefore, TNFRSF1B may become an important regulatory factor in the progression of colon cancer by participating in intracellular functional regulation. CONCLUSIONS: This study constructed a prognostic risk model based on three ARGs and for the first time discovered that TNFRSF1B may become an important regulatory factor in cancer progression by participating in intracellular functional regulation.
摘要：
Schizophrenia (SCZ) is a debilitating, chronic mental disorder with an elusive etiology that significantly impacts the life expectancy of affected individuals. Metabolic syndrome (MetS) is a condition characterized by a combination of factors that increase the risk of cardiovascular diseases. MetS is more prevalent in individuals with SCZ and is a major factor that contributes to their reduced lifespan. This review scrutinizes the biological factors that predispose patients with SCZ to MetS, among which, genetic predisposition, dietary and lifestyle modifications, and the use of antipsychotic drugs (APs) play a significant role. The metabolic side effects of APs have been well studied. While studies have shed light on potential interventions to manage MetS in patients with SCZ, identifying precise biological targets to treat SCZ remains challenging. Therefore, further studies are warranted to enhance our comprehension of the intricate mechanisms underlying the susceptibility of patients with SCZ to MetS. These studies will be crucial in developing effective, targeted therapeutic strategies to treat MetS in this vulnerable population.
期刊：
Applied Biochemistry and Biotechnology,2025年197(4):2579-2597 ISSN：0273-2289
通讯作者：
Liu, PL
作者机构：
[Liu, Pulin; Wang, Siyi; Zhu, Kai] Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430023, Peoples R China.
通讯机构：
[Liu, PL ] W;Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430023, Peoples R China.
关键词：
Glucan 1,4-alpha-maltohydrolase;Pichia pastoris;Rational design;Signal leading sequence;Fermentation
摘要：
Glucan 1,4-alpha-maltohydrolase (3.2.1.133, GMH) is an important biocatalyst in the baking industry, which could delay the retrogradation of bread and improve its cold-storage durability. In the present study, a newly cloned Thgmh was characterized and secreted by Pichia pastoris (Komagataella pastoris). After computationally assisted rational design that promotes peptide folding, the maltogenic activity in supernatant was enhanced 1.6-fold in comparison with the base strain. The signal leading sequence screening and the gene dosage increment further improved secretion by approximately 6.4-fold. The purified rationally designed ThGMHs exhibited maximal activity against soluble starch at pH 7.0 and 60℃, and maltose is the main catalytic product. In a 5-L bioreactor, conventional fed-batch fermentation resulted in 6130 U mL(-1) extracellular maltogenic activity. Therefore, a promising strain for GMH production was developed, which provides a useful reference for the secretory production of other industrial enzymes.
摘要：
Aims: Flavobacterium strains are widely distributed in various environments and generally exhibit specialized roles in the degradation of complex organic substrates. To obtain a deeper understanding of their enzyme profiles, patterns of action on natural carbohydrates degradation, and to mine gene resources for biomass conversion. Methods and results: We sequenced the whole genome of a novel carbohydrate-degrading Flavobacterium sp. strain YJ01. The genome size of strain YJ01 was 5.48 Mb and encoded 4674 predicted genes. Comparative genomic analysis revealed Flavobacterium strains were characterized by the presence of abundant genes associated with catalytic activity and metabolic processes, especially carbohydrate metabolism. About 9% of genes of strain YJ01 encoded carbohydrate-active enzymes. These enzymes can act on various complex natural and cellular carbohydrates. The synergistic effect of the enzymes on the hydrolysis of complex natural polysaccharides was further experimentally evidenced by using starch and xylan as substrates, in which the degradation rate of an enzyme combination was similar to 10-fold higher than that of the single enzyme. Conclusions: Flavobacterium sp. strain YJ01 has a high degree of catalytic and metabolic activity toward carbohydrates, and it harbors abundant, complete, and efficient enzymes for mediating complex polysaccharide degradation. These enzymes, acting synergistically on complex substrates, greatly improved the efficiency of digestion, which may be associated with the extensive ecological adaptability of Flavobacterium, which genetically heterologous divergent from extremely environments origin Flavobacterium strains. Impact Statement: The genomic profiling of strain YK01 not only provided a deeper understanding of the gene network for the utilization of natural carbohydrates but also supplied resources for mining enzymes involved in biomass conversion.
作者机构：
[Duan, Linlin; Duan, Haitao; Duan, HT; Jia, Dan; Li, Jian] Wuhan Res Inst Mat Protect, State Key Lab Special Surface Protect Mat & Applic, Wuhan 430030, Peoples R China.;[Duan, Linlin; Duan, Haitao; Duan, HT; Jia, Dan; Li, Jian] Hubei Longzhong Lab, Xiangyang 441000, Peoples R China.;[Liu, Jianfang] Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430030, Peoples R China.
通讯机构：
[Duan, HT ] W;Wuhan Res Inst Mat Protect, State Key Lab Special Surface Protect Mat & Applic, Wuhan 430030, Peoples R China.;Hubei Longzhong Lab, Xiangyang 441000, Peoples R China.
摘要：
In this work, the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid-liquid nanosized contact interface is taken, and the superior friction-reducing property of Cu3(PO4)2 center dot 3H2O (CuP) oil-based additives has been confirmed for titanium alloy. Three-dimensional (3D) CuP nanoflowers (CuP-Fs) with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil. Lubrication by CuP-Fs additives for titanium alloy, friction coefficient (COF) can be reduced by 73.68%, and wear rate (WR) reduced by 99.69%. It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid-liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules. However, any steric hindrance or connection between this repulsive solid-liquid interface will trigger the adhesion and increase the viscous shear force, for example, dispersant, hydrogen bondings, and shaky adsorbed water molecules. Besides, the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties. Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.
作者机构：
[Duan, Linlin; Duan, Haitao; Li, Guozheng; Duan, HT; Jia, Dan] Wuhan Res Inst Mat Protect, State Key Lab Special Surface Protect Mat & Applic, Wuhan 430030, Peoples R China.;[Duan, Linlin; Duan, Haitao; Li, Guozheng; Duan, HT; Jia, Dan] Hubei Longzhong Lab, Xiangyang 441000, Peoples R China.;[Liu, Jianfang] Wuhan Polytech Univ, Coll Life Sci & Technol, Wuhan 430030, Peoples R China.;[Cheng, Bingxue] Tsinghua Univ, State Key Lab Tribol Adv Equipment, Beijing 100084, Peoples R China.
通讯机构：
[Duan, HT ] W;Wuhan Res Inst Mat Protect, State Key Lab Special Surface Protect Mat & Applic, Wuhan 430030, Peoples R China.;Hubei Longzhong Lab, Xiangyang 441000, Peoples R China.
摘要：
In this work, a self-assembled hybrid phosphate nanoflower (HPN) containing Ba3(PO4)2 and NaBaPO4 was synthesized via BaCO3 primary crystals inducement. A ball-on-disc reciprocating tribometer was used to explore the tribological behavior of HPN as an additive for polyalphaolefin 8 (PAO8) on titanium alloy. Compared with the neat PAO8, after being lubricated with PAO8 containing HPN, the friction coefficient and wear rate decreased by 74.98% and 99.89%, respectively. The tribofilm at the friction interface was characterized and conformed by SEM, EDS, XPS, and cross-sectional TEM. As an additive to PAO8, HPN can participate in the formation of tribofilm and exhibit superior friction-reducing and anti-wear properties for titanium alloy. It was demonstrated that due to the P-O-Ti bonds, HPN can easily adsorb and deposit at the friction interface to form a tribofilm against wear. Besides, the simulation experiments showed that the repulsive force at the solid-liquid interface between HPN and oil molecules is the key to friction reduction and lubrication, and the comparative tribological experiments of different types of base oils were performed to verify the results of molecular dynamics.
通讯机构：
[Min, T ] W;Wuhan Polytech Univ, Coll Food Sci & Engn, Wuhan 430023, Peoples R China.
关键词：
Cinnamaldehyde;Fresh -cut Chinese water chestnuts;Reactive oxygen species (ROS);AsA-GSH cycle
摘要：
The quality of fresh -cut Chinese water chestnuts (CWCs) rapidly deteriorates with prolonged storage time, thus affecting its commercial value. This study aimed to investigate the effect of cinnamaldehyde (CA) treatment on the quality of fresh -cut CWCs and its mechanism of action. CA treatment maintained good appearance and higher total soluble solids content (TSS) of fresh -cut CWCs and also significantly inhibited microbial proliferation, respiration, phenylalanine ammonia-lyase activity (PAL) and enzymatic browning substance content. Moreover, CA treatment increased the antioxidant capacity and defense function -related enzyme activities (PPO and POD) of fresh -cut CWCs, and suppressed center dot OH production rate and MDA content. Meanwhile, CA treatment significantly increased the content of antioxidant compounds and enzyme activities of the AsA-GSH cycle system. In conclusion, CA can inhibit surface discoloration of fresh -cut CWCs and extend their shelf life, thus increasing their commercial value.
