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1.
J Agric Food Chem ; 72(19): 11268-11277, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38695399

RESUMO

Buttermilk is a potential material for the production of a milk fat globule membrane (MFGM) and can be mainly classified into two types: whole cream buttermilk and cheese whey cream buttermilk (WCB). Due to the high casein micelle content of whole cream buttermilk, the removal of casein micelles to improve the purity of MFGM materials is always required. This study investigated the effects of rennet and acid coagulation on the lipid profile of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW) and compared them with WCB. BRW has significantly higher phospholipids (PLs) and ganglioside contents than BAW and WCB. The abundance of arachidonic acid (ARA)- and eicosapentaenoic acid (EPA)-structured PLs was higher in WCB, while docosahexaenoic acid (DHA)-structured PLs were higher in BRW, indicating that BRW and WCB intake might have a greater effect on improving cardiovascular conditions and neurodevelopment. WCB and BRW had a higher abundance of plasmanyl PL and plasmalogen PL, respectively. Phosphatidylcholine (PC) (28:1), LPE (20:5), and PC (26:0) are characteristic lipids among BRW, BAW, and WCB, and they can be used to distinguish MFGM-enriched whey from different sources.


Assuntos
Leitelho , Queijo , Cabras , Lipidômica , Soro do Leite , Animais , Leitelho/análise , Queijo/análise , Soro do Leite/química , Fosfolipídeos/análise , Fosfolipídeos/química , Glicolipídeos/química , Leite/química , Gotículas Lipídicas/química , Glicoproteínas/química , Glicoproteínas/análise , Lipídeos/química , Lipídeos/análise
2.
J Agric Food Chem ; 72(1): 933-945, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38153029

RESUMO

Buttermilk, a potential material used to produce milk fat globule membrane (MFGM), is obtained as a byproduct of butter making from milk whole cream and cheese whey cream. This study investigated the effects of rennet and acid coagulation on the protein profiles of buttermilk rennet-coagulated whey (BRW) and buttermilk acid-coagulated whey (BAW). They were compared to those of whey cream buttermilk (WCB). Rennet coagulation was more efficient in removing casein, while retaining more IgG and lactoferrin than acid coagulation. BRW had more MFGM than BAW. Butyrophilin, xanthine dehydrogenase, and mucin1 were significantly higher (P < 0.05) in BRW, while fatty acid-binding protein 3 was enriched in BAW. KEGG analysis showed that complement and coagulation cascades had the greatest differences, and the abundance of proteins involved in this signaling pathway in BRW and BAW was higher, suggesting their potential anticoagulant and anti-inflammatory activity. BAW had higher apolipoprotein A4 and transcobalamin 2, which are essential carriers for transporting long-chain fatty acids and vitamin B12 from the intestine to the blood. Therefore, BAW intake might improve lipids and vitamin B12 absorption. This study can help deepen the understanding of protein composition of MFGM-enriched whey and facilitate the production of MFGM proteins for infants and old-aged populations.


Assuntos
Leitelho , Queijo , Produtos Fermentados do Leite , Animais , Humanos , Pessoa de Meia-Idade , Idoso , Soro do Leite , Cabras , Proteômica , Glicolipídeos/química , Proteínas do Soro do Leite , Gotículas Lipídicas , Vitamina B 12 , Proteínas do Leite/química
3.
Food Res Int ; 171: 113043, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37330850

RESUMO

Isomaltodextrins (IMDs) are starch-based dietary fibers (DF) prepared enzymatically, which show great potential as a functional food ingredient. In this study, a series of novel IMDs with diverse structures were generated by 4,6-α-glucanotransferase GtfBΔN from Limosilactobacillus fermentum NCC 3057, combined with two α-1,2 and α-1,3 branching sucrases. Results indicated that α-1,2 and α-1,3 branching significantly improved the DF contents of α-1,6 linear products up to 60.9-62.8%. When altering the ratios of [sucrose]/[maltodextrin], IMDs containing 25.8-89.0% α-1,6 bonds, 0-59.6% α-1,2 bonds and 0-35.1% α-1,3 bonds and Mw ranged from 1967 to 4876 Da were obtained. Physicochemical property analysis showed that grafting with α-1,2 or α-1,3 single glycosyl branches can improve the solubility of the α-1,6 linear product, in which α-1,3 branched products were better. Moreover, α-1,2 or α-1,3 branching did no effect on the viscosity of the products but Mw did, the larger Mw the greater viscosity. In addition, α-1,6 linear and α-1,2 or α-1,3 branched IMDs all exhibited strong acid-heating stabilities, freeze-thaw stabilities, and good resistance to browning caused by the Maillard reaction. Branched IMDs showed excellent storage stabilities at room temperature for one year at a concentration of 60%, whereas 45% α-1,6 linear IMD precipitated quickly within 12 h. Most importantly, α-1,2 or α-1,3 branching remarkably increased the contents of resistant starch in the α-1,6 linear IMDs to 74.5-76.8%. These clear qualitative assessments demonstrated the outstanding processing and application properties of the branched IMDs and were expected to provide valuable perspectives toward the technological innovation of functional carbohydrates.


Assuntos
Amido , Sacarase , Amido/química , Fibras na Dieta/análise , Digestão
4.
Food Chem ; 426: 136554, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37321121

RESUMO

Starch-based dietary fibers are at the forefront of functional ingredient research. In this study, a novel water-soluble slow digestion dextrin (SDD) was synthesized by synergy of α-glucosidase and cyclodextrin glucosyltransferase and characterized. Results showed that SDD exhibited high solubility, low viscosity, and resistance to digestive enzymes, and also showed an increased dietary fiber content of 45.7% compared with that of α-glucosidase catalysis alone. Furthermore, SDD was used as the sole carbon source to ferment selected intestinal strains and human fecal microflora in vitro to investigate its prebiotic effects. It was found that SDD could markedly enriched the abundance of Bifidobacterium, Veillonella, Dialister, and Blautia in human gut microflora and yielded higher total organic acid. The combination of α-glucosidase and cyclodextrin glucosyltransferase in this study showed valuable potential for the preparation of a novel slow digestion dextrin with good physicochemical properties and improved prebiotic effects.


Assuntos
Ciclodextrinas , Microbioma Gastrointestinal , Humanos , Prebióticos/análise , Dextrinas/análise , alfa-Glucosidases/análise , Ciclodextrinas/farmacologia , Glucosiltransferases , Fibras na Dieta/análise , Fezes/microbiologia , Digestão , Fermentação
5.
Bioprocess Biosyst Eng ; 46(6): 903-911, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37103578

RESUMO

2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G) is a stable derivative of L-ascorbic acid (L-AA), which has been widely used in food and cosmetics industries. Sugar molecules, such as glucose and maltose produced by cyclodextrin glycosyltransferase (CGTase) during AA-2G synthesis may compete with L-AA as the acceptors, resulting in low AA-2G yield. Multiple sequence alignment combined with structural simulation analysis indicated that residues at positions 191 and 255 of CGTase may be responsible for the difference in substrate specificity. To investigate the effect of these two residues on the acceptor preference and the AA-2G yield, five single mutants Bs F191Y, Bs F255Y, Bc Y195F, Pm Y195F and Pm Y260F of three CGTases from Bacillus stearothermophilus NO2 (Bs), Bacillus circulans 251 (Bc) and Paenibacillus macerans (Pm) were designed for AA-2G synthesis. Under optimal conditions, the AA-2G yields of the mutants Bs F191Y and Bs F255Y AA-2G were 34.3% and 7.9% lower than that of Bs CGTase, respectively. The AA-2G yields of mutant Bc Y195F, Pm Y195F and Pm Y260F were 45.8%, 36.9% and 12.6% higher than those of wild-type CGTases, respectively. Kinetic studies revealed that the residues at positions 191 and 255 of the three CGTases were F, which decreased glucose and maltose specificity and increased L-AA specificity. This study not only proposes for the first time that the AA-2G yield can be improved by weakening the acceptor specificity of CGTase toward sugar byproducts, but also provides new insight on the modification of CGTase that catalyze the double-substrate transglycosylation reaction.


Assuntos
Glucose , Maltose , Cinética , Ácido Ascórbico , Geobacillus stearothermophilus , Glucosiltransferases/química , Especificidade por Substrato
6.
Microb Cell Fact ; 22(1): 42, 2023 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-36864487

RESUMO

BACKGROUND: Adding acid protease to feed can enhance protein digestibility, boost feed utilization, and stimulate the growth of animals in breading industry. In order to obtain an acid protease with high hydrolysis efficiency to plant protein, in this study, an aspartic protease from Aspergillus niger was heterologous expressed in Pichia pastoris (P. pastoris). The enzymatic properties and application in soybean protein degradation were also studied. RESULTS: In our investigation, the high aspartic protease (Apa1) activity level of 1500 U/mL was achieved in 3 L bioreactor. After dialysis and anion exchange chromatography, the total enzyme activity and specific enzyme activity were 9412 U and 4852 U/mg, respectively. The molecular weight of the purified protease was 50 kDa, while the optimal pH and temperature were 3.0 and 50 °C, respectively. It was stable at pH 2.0-5.0 and 30-60 °C. Apa1 was used to hydrolyze soybean isolate protein (SPI) at 40 °C and pH 3.0, and a high hydrolysis degree (DH) of 61.65% was achieved. In addition, the molecular weight distribution of SPI hydrolysis products was studied, the result showed that the hydrolysis products were primarily oligopeptides with molecular weights of 189 Da or below. CONCLUSIONS: In this study, Apa1 was successfully expressed in P. pastoris and high expression level was obtained. In addition, the highest protein hydrolysis rate to SPI degradation so far was achieved. The acid protease in this study provides a new protease that is suitable for the feed industry, which will be very helpful to improve the feed utilization and promote the development of the breeding industry.


Assuntos
Aspergillus niger , Proteínas de Soja , Animais , Proteólise , Hidrólise , Aspergillus niger/genética , Diálise Renal , Peptídeo Hidrolases , Endopeptidases , Glycine max
7.
Food Chem ; 416: 135865, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-36905711

RESUMO

In vitro coagulation and digestion of caprine and bovine micellar casein concentrate (MCC) with or without partial colloidal calcium depletion (deCa) were studied under simulated adult and elderly conditions. Gastric clots were smaller and looser for caprine than bovine MCC, and were further looser with deCa and under elderly condition for both caprine and bovine MCC. Casein hydrolysis and concomitant formation of large peptides was faster for caprine than bovine MCC, and with deCa and under adult condition for caprine and bovine MCC. Formation of free amino groups and small peptides were faster for caprine MCC, and with deCa and under adult condition. Upon intestinal digestion, proteolysis occurred rapidly, and was faster under adult condition, but showed less differences with increasing digestion between caprine and bovine MCC, and with and without deCa. These results suggested weakened coagulation and greater digestibility for caprine MCC and MCC with deCa under both conditions.


Assuntos
Caseínas , Micelas , Humanos , Animais , Bovinos , Idoso , Cálcio , Cabras , Peptídeos , Alérgenos , Digestão , Leite
8.
Appl Microbiol Biotechnol ; 107(7-8): 2483-2499, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36917273

RESUMO

Increasing cellulase production in cellulolytic fungus Trichoderma reesei is of interest for biofuels and biorefineries. Previous studies indicated that secreted protein was occasionally accumulated in vacuoles; this phenomenon has also been reported in T. reesei. Therefore, alleviating vacuolar transport seems to be a promising strategy for improving cellulase production in T. reesei. Herein, we found that knockout of vps10, vps13, and vps21, among 11 vacuolar protein sorting factors, improved cellulase production in T. reesei. The filter paper activity in Δvps10, Δvps13, and Δvps21 increased by 1.28-, 2.45-, and 2.11-fold than that of the parent strain. Moreover, the ß-glucosidase activity in Δvps13 and Δvps21 increased by 3.22- and 3.56-fold after 6 days of fermentation. Furthermore, we also found that the vacuolar trafficking towards vacuoles was partially impaired in three knockout mutants, and disruption of vps13 alleviated the autophagy process. These results indicated that alleviated transport and degradation towards vacuole in Δvps10, Δvps13, and Δvps21 might improve cellulase production. Of note, the expression of cellulase genes in Δvps13 and Δvps21 was dramatically increased in the late induction phase compared to the parent. These results suggested that Vps13 and Vps21 might influence the cellulase production at transcription level. And further transcriptome analysis indicated that increased cellulase gene expression might be attributed to the differential expression of sugar transporters. Our study unravels the effect of alleviating vacuolar transport through knockout vps10, vps13, and vps21 for efficient cellulase secretion, providing new clues for higher cellulase production in T. reesei. KEY POINTS: • Disruption of vps10, vps13 or vps21 improves cellulase production • Vacuolar transport is impaired in three vps KO mutants • Deletion of vps13 or vps21 increases the transcript of cellulase genes in late stage.


Assuntos
Celulase , Hypocreales , Trichoderma , Celulase/genética , Celulase/metabolismo , Trichoderma/genética , Trichoderma/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Hypocreales/metabolismo
9.
Front Microbiol ; 14: 1119232, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36891394

RESUMO

Introduction: ß-Mannanases can hydrolyze mannans, which are widely available in nature. However, the optimum temperature of most ß-mannanases is too low to be directly utilized in industry. Methods: To further improve the thermostability of Anman (mannanase from Aspergillus niger CBS513.88), B-factor and Gibbs unfolding free energy change were used to modify the flexible of Anman, and then combined with multiple sequence alignment and consensus mutation to generate an excellent mutant. At last, we analyzed the intermolecular forces between Anman and the mutant by molecular dynamics simulation. Results: The thermostability of combined mutant mut5 (E15C/S65P/A84P/A195P/T298P) was increased by 70% than the wild-type Amman at 70°C, and the melting temperature (Tm) and half-life (t1/2) values were increased by 2°C and 7.8-folds, respectively. Molecular dynamics simulation showed reduced flexibility and additional chemical bonds in the region near the mutation site. Discussion: These results indicate that we obtained a Anman mutant that is more suitable for industrial application, and they also confirm that a combination of rational and semi-rational techniques is helpful for screening mutant sites.

10.
Int J Biol Macromol ; 233: 123536, 2023 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-36740130

RESUMO

4,6-α-glucanotransferase (4,6-α-GT), as a member of the glycoside hydrolase 70 (GH70) family, converts starch/maltooligosaccharides into α,1-6 bond-containing α-glucan and possesses potential applications in food, medical and related industries but does not satisfy the high-temperature requirement due to its poor thermostability. In this study, a 4,6-α-GT (ΔGtfB) from Limosilactobacillus fermentum NCC 3057 was used as a model enzyme to improve its thermostability. The loops of ΔGtfB as the target region were optimized using directed evolution, sequence alignment, and computer-aided design. A total of 11 positive mutants were obtained and iteratively combined to obtain a combined mutant CM9, with high resistance to temperature (50 °C). The activity of mutant CM9 was 2.08-fold the activity of the wild type, accompanied by a 5 °C higher optimal temperature, a 5.76 °C higher melting point (Tm, 59.46 °C), and an 11.95-fold longer half-life time (t1/2). The results showed that most of the polar residues in the loop region of ΔGtfB are mutated into rigid proline residues. Molecular dynamics simulation demonstrated that the root mean square fluctuation of CM9 significantly decreased by "Breathing" movement reduction of the loop region. This study provides a new strategy for improving the thermostability of 4,6-α-GT through rational loop region modification.


Assuntos
Sistema da Enzima Desramificadora do Glicogênio , Limosilactobacillus fermentum , Sistema da Enzima Desramificadora do Glicogênio/química , Simulação de Dinâmica Molecular , Amido , Temperatura , Estabilidade Enzimática
11.
Environ Sci Pollut Res Int ; 30(16): 46997-47011, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36735135

RESUMO

Acetaminophen (AP) is a widely used antipyretic analgesic belonging to the class of PPCPs, which is difficult to be effectively degraded by traditional water treatment processes. However, photocatalytic technology may be an effective approach. Herein, B-doped TiO2 photocatalytic materials were synthesized by sol-gel method, calcinated at 600℃ for 2 h, investigated by XRD, TEM, XPS, and other characterization methods. The photocatalytic efficiency and factors affecting the photocatalytic activity were assessed by degradation of AP under 365 nm UV light. Compared with undoped TiO2, 4%B-TiO2 nanopowder has smaller grain size, higher porosity, and lower bandgap energy of 3.11 eV. Scavenging experiments and ESR results show that •OH is the principal active species. Hence, the degradation efficiency of AP is as high as 98.8% in 30 min when adopting 10-mg/L AP initial concentration and 1-g/L 4%B-TiO2 loading, owing to efficient •OH generated by B-TiO2.


Assuntos
Acetaminofen , Luz , Radical Hidroxila , Águas Residuárias , Catálise , Titânio
12.
Foods ; 12(3)2023 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-36766084

RESUMO

Sourdough fermentation has been widely used in food products. However, there has been limited study of the effect of co-fermentation with lactic acid bacteria and yeast on the dough and cracker products. In this study, the influence of co-fermentation with Lactobacillus plantarum HLJ29L2 (LP HLJ29L2) and yeast on wheat protein digestibility of cracker was studied, and the mechanism of the protein changes in sourdough during fermentation was further explored. Co-fermentation with LP HLJ29L2 and yeast (DN-1) strongly improved the protein digestibility of cracker. At the same time, the content of free amino acids in DN-1 crackers increased by 20%. Co-fermentation also had significant effect on the sourdough during fermentation. The SDS-soluble protein content in sourdough was increased, and large molecule proteins were significantly reduced in the DN-1 sourdough. This was due to the fact, that LP HLJ29L2 grew rapidly during co-fermentation and produced more organic acids, which led to an increase in protease activity in sourdough and promoted the degradation of protein by proteases. The results of this study provide an important theoretical basis for the application of lactic acid bacteria and yeast co-fermentation in crackers.

13.
Appl Microbiol Biotechnol ; 107(4): 1233-1241, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36688952

RESUMO

In this study, site saturation mutagenesis was performed on the - 3 (R44, D86, S90, and D192) and - 6 subsite (Y163, G175, G176, and N189) of Bacillus stearothermophilus NO2 cyclodextrin glucosyltransferase to enhance its specificity for the donor substrate maltodextrin for 2-O-α-D-glucopyranosyl-L-ascorbic acid (AA-2G) preparation. The AA-2G yields produced by the mutants S90D, G176H, and S90D/G176H were 181, 171, and 185 g/L, respectively. Our previous study found that the mutant K228R/M230L also increased the AA-2G yield. Therefore, the mutants S90D, G176H, S90D/G176H, and K228R/M230L were further used to generate combinatorial mutants. Among these mutants, the highest AA-2G yield (217 g/L) was produced by S90D/K228R/M230L with 500 g/L maltodextrin as the glucosyl donor, which was 56 g/L higher than that produced by wild-type CGTase. In addition, AA-2G was prepared by adding isoamylase to hydrolyze α-1,6 glucosidic linkages in maltodextrin that could not be utilized by CGTase to improve the utilization rate of maltodextrin. The addition of isoamylase reduced the concentration of maltodextrin from 500 to 350 g/L, while the AA-2G yield remained high (208 g/L). The preparation of AA-2G by complexing isoamylase with mutant S90D/K228R/M230L reduced the maltodextrin concentration by 150 g/L, while the AA-2G yield increased by 47 g/L than preparation with wild-type CGTase alone, which laid a foundation for the large-scale preparation of AA-2G. KEY POINTS: • Mutants exhibited improved maltodextrin specificity. • Mutant S90D/K228R/M230L produced high yield of AA-2G with maltodextrin as substrate. • AA-2G was first synthesized by a combination of isoamylase and CGTase.


Assuntos
Isoamilase , Paenibacillus , Mutagênese Sítio-Dirigida , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Cinética , Paenibacillus/genética , Especificidade por Substrato , Ácido Ascórbico
14.
Foods ; 11(21)2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36360082

RESUMO

In this study, a potential producer of prebiotics, a novel endo-polygalacturonase pePGA from Penicillium rolfsii BM-6, was successfully expressed in Komagataella phaffii, characterized and applied to produce pectic oligosaccharides. The optimum temperature and pH of pePGA were 60 °C and 6.0. The purified recombinant enzyme showed a good pH stability and was stable from pH 3.5 to 8.0. The Km, Vmax and kcat values of pePGA were 0.1569 g/L, 12,273 µmol/min/mg and 7478.4 s-1, respectively. More importantly, pePGA-POS, the pePGA hydrolysis products from commercial pectin, had good prebiotic and antibacterial activities in vitro. The pePGA-POS was able to significantly promote the growth of probiotics; meanwhile, the growth of Escherichia coli JM109, Staphylococcus aureus and Bacillus subtilis 168 was effectively inhibited by pePGA-POS. In addition, pePGA-POS also had the DPPH radical scavenging capacity. These properties of pePGA-POS make pePGA attractive for the production of prebiotics.

15.
Molecules ; 27(18)2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36144726

RESUMO

In vivo metabolism of polyethylene glycol (PEG) hydrogels has rarely been studied. In this study, we prepared a chemically crosslinked hydrogel formulation using 14C-labeled tetra-armed poly (ethylene glycol) succinimidyl succinate (Tetra-PEG-SS) and 3H-labeled crosslinking agent for implantation into the pelvis of Sprague-Dawley (SD) rats. This radioactive labeling technique was used to investigate the radioactivity excretion rates in of feces and urine, the blood exposure time curve, and the radioactivity recovery rate in each tissue over time. We showed that the primary excretion route of the hydrogel was via urine (3H: about 86.4%, 14C: about 90.0%), with fewer portion through feces (3H: about 6.922%, 14C: about 8.16%). The hydrogel metabolites exhibited the highest distribution in the kidney, followed by the jejunal contents; The 3H and 14C radioactivity exposures in the remaining tissues were low. We also showed that the 3H and 14C radioactivity recovery rates in the blood were usually low (<0.10% g−1 at 12 h after implantation), even though, in theory, the hydrogel could be absorbed into the blood through the adjacent tissues. By using a combination of HPLC-MS/MS and offline radioactivity counting method, we established that the tetra-PEG-based hydrogel was mainly metabolized to lower-order PEG polymers and other low-molecular-weight substances in vivo.


Assuntos
Polietilenoglicóis , Espectrometria de Massas em Tandem , Animais , Materiais Biocompatíveis/química , Hidrogéis/química , Pelve , Polietilenoglicóis/química , Polímeros , Ratos , Ratos Sprague-Dawley , Succinatos
16.
Int J Biol Macromol ; 210: 315-323, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35545138

RESUMO

4,6-α-Glucanotransferases (4,6-α-GTs) hold great potential for applications in the food and medical industries because of their efficient transglycosylation ability. However, it is relatively difficult to achieve high soluble expression because of their high molecular weight and multidomain nature. In this study, 4,6-α-GT of Burkholderia sp. (GtfR2) was successfully expressed in E. coli, and the activity attained 1.55 × 104 U/mL by traditional fermentation optimization. However, a large number of inactive inclusion bodies of GtfR2 were still present due to aggregation and precipitation. The trehalose-mediated strategy was first proposed and applied in the fermentation process of GtfR2. Trehalose addition significantly reduced inclusion bodies, resulting in an increase in GtfR2 activity (6.48 × 104 U/mL), which was 4.20 times higher than that of the control group. Our molecular dynamics simulations revealed that trehalose could spontaneously stabilize the conformational dynamics of GtfR2 by binding to the groove, loop, α-helix and N-terminal unstable regions on the surface. This strategy was also available to enhance the soluble expression of other 4,6/4,3-α-GTs, which were increased by 3.03-77.19 times. This study is the first to observe that trehalose can inhibit the aggregation and precipitation of GtfR2, which provides a new perspective for the recombinant expression of 4,6/4,3-α-GTs.


Assuntos
Escherichia coli , Sistema da Enzima Desramificadora do Glicogênio , Escherichia coli/genética , Escherichia coli/metabolismo , Sistema da Enzima Desramificadora do Glicogênio/metabolismo , Corpos de Inclusão/metabolismo , Trealose/metabolismo , Trealose/farmacologia
17.
Environ Sci Pollut Res Int ; 29(27): 40854-40864, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35083676

RESUMO

In this paper, Y-ZrO2-TiO2 photocatalyst was prepared by sol-gel method, the titanium source was tetrabutyl titanate, and the precursors were zirconium nitrate pentahydrate and yttrium nitrate hexahydrate. For the photocatalytic effect of Y-ZrO2-TiO2 to hydroquinone, these effects were investigated: doping ratios of Zr/Y, calcination conditions, pH, etc. And the materials were characterized by XRD, TEM-EDS, XPS, PL, ESR, etc. The results showed that the optimum preparation conditions of Y-ZrO2-TiO2 photocatalyst were as follows: the molar ratio of doping was Ti: Zr: Y = 100:6:0.5, the calcination temperature was 500 °C, and the calcination time was 2 h; the optimum reaction conditions were as follows: the dosage of Y-ZrO2-TiO2 was 1 g/L, and pH value was 6.96. The degradation rate of hydroquinone under 365-nm UV lamp for 50 min could reach 96.58%, while the degradation rates of pure TiO2, Y-TiO2, and ZrO2-TiO2 under the same conditions were 33.95%, 79.55%, and 90.30%, respectively. It can be seen that the addition of elements Zr and Y improves the photocatalytic performance of TiO2.


Assuntos
Hidroquinonas , Nitratos , Catálise , Titânio/química
18.
Chemosphere ; 291(Pt 3): 133032, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34843831

RESUMO

Bimetallic MOFs (MIL-53 (Fe, Al)) were successfully fabricated via a facile one-step solvothermal method for the removal of tetracycline (TC) from aqueous solutions. Tetracycline adsorption and photocatalytic experiments indicate that the optimum bimetallic synthetic molar ratio is 3:2 (40%MIL-53(Fe, Al)). The adsorption data are well fitted by the Freundlich model and pseudo-second-order adsorption kinetics. 40%MIL-53(Fe, Al) has an adsorption capacity of up to 402.033 mg/g. After the dark adsorption phase, 10 mg of 40%MIL-53(Fe, Al) can remove 94.33% of the tetracycline in a 70 mL aqueous solution (20 mg/L) under 50 min irradiation, while only 71.39% and 81.82% of the tetracycline are removed by MIL-53(Fe) and MIL-53(Al) under the same conditions. In addition, 40%MIL-53(Fe, Al) exhibits a significant adsorption-photocatalytic synergy (under direct irradiation without a dark adsorption phase), in which the pseudo-first-order kinetic constant increases by a factor of 3.11. Quenching experiments and ESR characterization indicate that ·O2-, ·OH, and h+ are the main active species in the photocatalytic process. Meanwhile, 40%MIL-53(Fe, Al) demonstrates good stability, with a tetracycline removal rate that still reaches 83.70% after 4 cycles. These results suggest that the prepared 40%MIL-53(Fe, Al) catalyst is a novel adsorption-photocatalytic material that can be used for the efficient treatment of tetracycline.


Assuntos
Antibacterianos , Tetraciclina , Adsorção
19.
Environ Res ; 199: 111258, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34029543

RESUMO

The paper microzones method (PMZs) is a green chemical method that uses the principle of the three primary colors of red, green and blue (RGB) to detect the water quality of the droplets on white paper. However, this method is rarely used in the performance evaluation of photocatalysts. The paper details the first use of paper microzones utilized in the evaluation of photocatalyst performance. A sol-gel method was used to prepare molecularly imprinted modified TiO2 photocatalysts for the treatment of different wastewaters, and characterized the catalysts using XRD and several other methods. The reliability of PMZs on the evaluation of photocatalytic activity and selectivity was also analyzed. The following results were obtained: EP-TiO2 catalysts (EP, ethyl paraben, the imprinting molecule) with different S doping levels were synthesized using a one-step sol-gel method, and the best S doping ratio was found to be n(Ti):n(S) 3:1. S-EP-TiO2 was found to be 100% anatase and showed excellent photocatalytic performance, while the PMZs method accurately determined changes in RGB levels for the photocatalytic degradation process of pollutants using S-EP-TiO2 as the photocatalyst. A photocatalytic kinetic analysis showed the PMZs method was quite suitable for the evaluation of photocatalyst activity, but the evaluation of selectivity needs improvement. This method is a promising green chemistry way to evaluate photocatalyst performance and the rapid detection of outdoor sewage water quality.


Assuntos
Titânio , Catálise , Cinética , Reprodutibilidade dos Testes
20.
Pharm Res ; 37(7): 146, 2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32666340

RESUMO

PURPOSE: The objective of the present work was to prepare safe and effective Ciclosporin A Lipid nanocapsule (CsA-LNC) eye-drops for the treatment of DED. METHODS: The phase-inversion method was used to prepared different sizes CsA-LNC. CsA biodistribution in ocular after topical administration in rabbits was analyzed by a validated UPLC-MS/MS method. The efficacy of CsA-LNCs (25 nm, 50 nm, 85 nm) was evaluated using the tear breakup time, fluorescein staining, tear production, inflammatory cytokines and histopathology tests. The safety of CsA-LNCs was study by the score of ocular irritation and histological examination study. RESULTS: CsA-LNCs(20-100 nm) were successfully prepared, An in vivo PK study showed significant improvement of the bioavailability (4.20-fold (25 nm), 2.15-fold (50 nm) and 2.33-fold (85 nm)) in bulbar conjunctiva, and great permeability was observed in the cornea for CsA-LNCs compared with CsA emulsion. An in vivo PD study showed that CsA-LNCs have great efficacy for DED, and the effect was improved over CsA emulsion. CsA-LNCs were safe and not cause significant irritation to the eyes surface of rabbits. CONCLUSION: This work has demonstrated CsA-LNCs, in particular small sizes CsA-LNC, are safe and effective with promising potential to treat DED. Grapical abstract.


Assuntos
Ciclosporina/administração & dosagem , Ciclosporina/uso terapêutico , Síndromes do Olho Seco/tratamento farmacológico , Administração Oftálmica , Animais , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Ciclosporina/farmacocinética , Citocinas/metabolismo , Sistemas de Liberação de Medicamentos , Irritantes , Lipídeos/química , Masculino , Espectrometria de Massas , Nanopartículas , Soluções Oftálmicas , Coelhos , Ratos , Ratos Sprague-Dawley , Lágrimas , Distribuição Tecidual
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