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1.
Nano Lett ; 22(6): 2228-2235, 2022 03 23.
Artigo em Inglês | MEDLINE | ID: mdl-35235332

RESUMO

Calcium-ion batteries (CIBs) are a promising alternative to lithium-ion batteries (LIBs) due to the low redox potential of calcium metal and high abundance of calcium compounds. Due to its layered structure, α-MoO3 is regarded as a promising cathode host lattice. While studies have reported that α-MoO3 can reversibly intercalate Ca ions, limited electrochemical activity has been noted, and its reaction mechanism remains unclear. Here, we re-examine Ca insertion into α-MoO3 nanoparticles with a goal to improve reaction kinetics and clarify the storage mechanism. The α-MoO3 electrodes demonstrated a specific capacity of 165 mA h g-1 centered near 2.7 V vs Ca2+/Ca, stable long-term cycling, and good rate performance at room temperature. This work demonstrates that, under the correct conditions, layered oxides can be a promising host material for CIBs and renews prospects for CIBs.


Assuntos
Cálcio , Nanopartículas , Eletrodos , Íons , Lítio/química
2.
Nano Lett ; 22(23): 9470-9476, 2022 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-36455210

RESUMO

Materials for studying biological interactions and for alternative energy applications are continuously under development. Semiconductor quantum dots are a major part of this landscape due to their tunable optoelectronic properties. Size-dependent quantum confinement effects have been utilized to create materials with tunable bandgaps and Auger recombination rates. Other mechanisms of electronic structural control are under investigation as not all of a material's characteristics are affected by quantum confinement. Demonstrated here is a new structure-property concept that imparts the ability to spatially localize electrons or holes within a core/shell heterostructure by tuning the charge carrier's kinetic energy on a parabolic potential energy surface. This charge carrier separation results in extended radiative lifetimes and in continuous emission at the single-nanoparticle level. These properties enable new applications for optics, facilitate novel approaches such as time-gated single-particle imaging, and create inroads for the development of other new advanced materials.


Assuntos
Nanopartículas , Pontos Quânticos , Pontos Quânticos/química , Nanopartículas/química , Semicondutores , Elétrons , Eletrônica
3.
Chemphyschem ; 23(1): e202100645, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34626067

RESUMO

Hexagonal boron nitride (h-BN) and exfoliated nanosheets (BNNs) not only resemble their carbon counterparts graphite and graphene nanosheets in structural configurations and many excellent materials characteristics, especially the ultra-high thermal conductivity, but also offer other unique properties such as being electrically insulating and extreme chemical stability and oxidation resistance even at elevated temperatures. In fact, BNNs as a special class of 2-D nanomaterials have been widely pursued for technological applications that are beyond the reach of their carbon counterparts. Highlighted in this article are significant recent advances in the development of more effective and efficient exfoliation techniques for high-quality BNNs, the understanding of their characteristic properties, and the use of BNNs in polymeric nanocomposites for thermally conductive yet electrically insulating materials and systems. Major challenges and opportunities for further advances in the relevant research field are also discussed.


Assuntos
Grafite , Nanocompostos , Compostos de Boro , Condutividade Térmica
4.
Microb Cell Fact ; 18(1): 7, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30654816

RESUMO

BACKGROUND: Multi-monocistronic and multi-variate vectors were designed, built, and tested for the improved production of cyanidin 3-O-glucoside (C3G) in Escherichia coli BL21 (DE3). The synthetic bio-parts were designed in such a way that multiple genes can be assembled using the bio-brick system, and expressed under different promoters in a single vector. The vectors harbor compatible cloning sites, so that the genes can be shuffled from one vector to another in a single step, and assembled into a single vector. The two required genes: anthocyanidin synthase (PhANS) from Petunia hybrida, and cyanidin 3-O-glucosyltransferase (At3GT) from Arabidopsis thaliana, were individually cloned under PT7, Ptrc, and PlacUV5 promoters. Both PhANS and At3GT were shuffled back and forth, so as to generate a combinatorial system for C3G production. The constructed systems were further coupled with the genes for UDP-D-glucose synthesis, all cloned in a multi-monocistronic fashion under PT7. Finally, the production of C3G was checked and confirmed using the modified M9 media, and analyzed through various chromatography and spectrometric analyses. RESULTS: The engineered strains endowed with newly generated vectors and the genes for C3G biosynthesis and UDP-D-glucose synthesis were fed with 2 mM (+)-catechin and D-glucose for the production of cyanidin, and its subsequent conversion to C3G. One of the engineered strains harboring At3GT and PhANS under Ptrc promoter and UDP-D-glucose biosynthesis genes under PT7 promoter led to the production of ~ 439 mg/L of C3G within 36 h of incubation, when the system was exogenously fed with 5% (w/v) D-glucose. This system did not require exogenous supplementation of UDP-D-glucose. CONCLUSION: A synthetic vector system using different promoters has been developed and used for the synthesis of C3G in E. coli BL21 (DE3) by directing the metabolic flux towards the UDP-D-glucose. This system has the potential of generating better strains for the synthesis of valuable natural products.


Assuntos
Antocianinas/biossíntese , Escherichia coli/metabolismo , Glucosídeos/biossíntese , Antocianinas/análise , Reatores Biológicos , Catequina/metabolismo , Cromatografia Líquida de Alta Pressão , Glucose/metabolismo , Glucosídeos/análise , Glucosiltransferases/genética , Engenharia Metabólica , Oxigenases/genética , Proteínas de Plantas/genética , Plasmídeos/genética , Plasmídeos/metabolismo
5.
Appl Microbiol Biotechnol ; 102(3): 1251-1267, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29308528

RESUMO

Two plant-originated C-glucosyltransferases (CGTs) UGT708D1 from Glycine max and GtUF6CGT1 from Gentiana triflora were accessed for glucosylation of selected flavones chrysin and luteolin. Uridine diphosphate (UDP)-glucose pool was enhanced in Escherichia coli cell cytosol by introducing heterologous UDP-glucose biosynthetic genes, i.e., glucokinase (glk), phosphoglucomutase (pgm2), and glucose 1-phosphate uridylyltransferase (galU), along with glucose facilitator diffusion protein from (glf) from different organisms, in a multi-monocistronic vector with individual T7 promoter, ribosome binding site, and terminator for each gene. The C-glucosylated products were analyzed by high-performance liquid chromatography-photodiode array, high-resolution quadruple time-of-flight electrospray ionization mass spectrometry, and one-dimensional nuclear magnetic resonance analyses. Fed-batch shake flask culture showed 8% (7 mg/L; 16 µM) and 11% (9 mg/L; 22 µM) conversion of chrysin to chrysin 6-C-ß-D-glucoside with UGT708D1 and GtUF6CGT1, respectively. Moreover, the bioengineered E. coli strains with exogenous UDP-glucose biosynthetic genes and glucose facilitator diffusion protein enhanced the production of chrysin 6-C-ß-D-glucoside by approximately 1.4-fold, thus producing 10 mg/L (12%, 24 µM) and 14 mg/L (17%, 34 µM) by UGT708D1 and GtUF6CGT1, respectively, without supplementation of additional UDP-glucose in the medium. The biotransformation was further elevated when the bioengineered strain was scaled up in lab-scale fermentor at 3 L volume. HPLC analysis of fermentation broth extract revealed 50% (42 mg/L, 100 µM) conversion of chrysin to chrysin 6-C-ß-D-glucoside at 48 h upon supplementation of 200 µM of chrysin. The maximum conversion of luteolin was 38% (34 mg/L, 76 µM) in 50-mL shake flask fermentation at 48 h. C-glucosylated derivative of chrysin was found to be more soluble and more stable to high temperature, different pH range, and ß-glucosidase enzyme, than O-glucosylated derivative of chrysin.


Assuntos
Escherichia coli/metabolismo , Flavonas/biossíntese , Glucosídeos/biossíntese , Engenharia Metabólica , Técnicas de Cultura Celular por Lotes , Vias Biossintéticas , Cromatografia Líquida de Alta Pressão , Escherichia coli/genética , Fermentação , Flavonoides/metabolismo , Gentiana/enzimologia , Glucoquinase/genética , Glucoquinase/metabolismo , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Luteolina/metabolismo , Fosfoglucomutase/genética , Fosfoglucomutase/metabolismo , Glycine max/enzimologia , Espectrometria de Massas por Ionização por Electrospray , Uridina Difosfato Glucose/metabolismo
6.
Biotechnol Appl Biochem ; 65(2): 128-137, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28608479

RESUMO

7,8-Dihydroxyflavone (7,8-DHF) has been conjugated with glucose moiety to produce glucoside derivatives. Three analogues of 7,8-DHF (7-O-ß-d-glucosyl-8-hydroxyflavone, 7-hydroxy-8-O-ß-d-glucosyl flavone, and 7,8-di-O-ß-d-glucosylflavone) have been successfully produced from in vitro reaction using glycosyltransferase of Bacillus licheniformis. Production of these 7,8-DHF derivatives were shifted to cheaper and easier approach in this study by using engineered Escherichia coli BL21 (DE3) ΔpgiΔzwfΔushA cells in which the flow of glucose-6-phospahte toward glycolysis and pentose phosphate pathway and hydrolysis of UDP-α-d-glucose were blocked while directing the carbon flux toward UDP-α-d-glucose by overexpressing UDP-α-d-glucose pathway genes. Supplementation of 300 µM of 7,8-DHF to the culture resulted in production of 171 µM of 7-O-ß-d-glucosyl-8-hydroxyflavone, 68 µM of 7-hydroxy-8-O-ß-d-glucoxyflavone, and 55 µM of 7,8-di-O-ß-d-glucoxyflavone in laboratory-scale 3-L fermentor, representing 98% bioconversion of initially fed substrate to respective glucoside derivatives within 48 H. These products were characterized by high-performance liquid chromatography-photodiode array (HPLC-PDA), HPLC-PDA-quadruple time of flight-electron spray ionization mass spectrometry, and nuclear magnetic resonance analyses. These newly synthesized derivatives were found to be able to interact with amino acids of active site of human ß-site amyloid precursor protein cleaving ß-site amyloid precursor protein cleaving enzyme 1 (BACE1) ß-secretase enzyme in in silico studies, thus displaying possible application in cure of Alzheimer's disease.


Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacologia , Flavonas/metabolismo , Flavonas/farmacologia , Glicosídeos/metabolismo , Glicosídeos/farmacologia , Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Bacillus licheniformis/enzimologia , Bacillus licheniformis/genética , Bacillus licheniformis/metabolismo , Vias Biossintéticas , Inibidores Enzimáticos/química , Escherichia coli/enzimologia , Escherichia coli/genética , Escherichia coli/metabolismo , Flavonas/química , Glicosídeos/química , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Humanos , Microbiologia Industrial/métodos , Engenharia Metabólica/métodos , Redes e Vias Metabólicas , Simulação de Acoplamento Molecular
7.
Molecules ; 23(9)2018 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-30154376

RESUMO

Anthraquinones, naturally occurring bioactive compounds, have been reported to exhibit various biological activities, including anti-inflammatory, antiviral, antimicrobial, and anticancer effects. In this study, we biotransformed three selected anthraquinones into their novel O-glucoside derivatives, expressing a versatile glycosyltransferase (YjiC) from Bacillus licheniformis DSM 13 in Escherichia coli. Anthraflavic acid, alizarin, and 2-amino-3-hydroxyanthraquinone were exogenously fed to recombinant E. coli as substrate for biotransformation. The products anthraflavic acid-O-glucoside, alizarin 2-O-ß-d-glucoside, and 2-amino-3-O-glucosyl anthraquinone produced in the culture broths were characterized by various chromatographic and spectroscopic analyses. The comparative anti-proliferative assay against various cancer cells (gastric cancer-AGS, uterine cervical cancer-HeLa, and liver cancer-HepG2) were remarkable, since the synthesized glucoside compounds showed more than 60% of cell growth inhibition at concentrations ranging from ~50 µM to 100 µM. Importantly, one of the synthesized glucoside derivatives, alizarin 2-O-glucoside inhibited more than 90% of cell growth in all the cancer cell lines tested.


Assuntos
Antraquinonas/química , Antraquinonas/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Glucosídeos/química , Glucosídeos/farmacologia , Antraquinonas/metabolismo , Antineoplásicos/metabolismo , Bactérias/metabolismo , Vias Biossintéticas , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Glucosídeos/biossíntese , Humanos , Espectroscopia de Ressonância Magnética , Espectrometria de Massas
8.
J Prosthodont ; 27(5): 416-420, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27338840

RESUMO

PURPOSE: To assess the reliability and to validate the translated Nepalese version of the Oral Health Impact Profile (OHIP-EDENT-N) in Nepalese edentulous subjects. MATERIALS AND METHODS: The international guidelines for translation and cross-cultural adaption of OHIP-EDENT were followed, and a Nepalese version of the questionnaire was adapted for this study. Eighty-eight completely edentulous subjects were then selected for the study and completed their responses for the questionnaire. The reliability of the OHIP-EDENT-N was evaluated using internal consistency. Validity was assessed as construct and convergent validity. Construct validity was determined using exploratory factor analysis (EFA). The correlation between OHIP-EDENT-N subscale scores and the global question was investigated to test the convergent validity. RESULTS: Cronbach's alpha for the total score of OHIP-EDENT-N was 0.78. Construct validity was assessed by factor analysis: 70.196% of the variance was accountable to five factors extracted from the factor analysis. Factor loadings above 0.40 were noted for all items. In terms of convergent validity, significant correlations could be established between OHIP-EDENT-N and global questions. CONCLUSIONS: This study has been able to establish the reliability and validity of the OHIP-EDENT-N, and OHIP-EDENT-N can be a considered a reliable tool to assess the oral health related quality of life in the Nepalese edentulous population.


Assuntos
Boca Edêntula/psicologia , Saúde Bucal , Qualidade de Vida , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Nepal , Reprodutibilidade dos Testes , Inquéritos e Questionários , Traduções
9.
Glycoconj J ; 33(2): 137-46, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26852037

RESUMO

Epothilone A is a derivative of 16-membered polyketide natural product, which has comparable chemotherapeutic effect like taxol. Introduction of sialic acids to these chemotherapeutic agents could generate interesting therapeutic glycoconjugates with significant effects in clinical studies. Since, most of the organisms biosynthesize sialic acids in their cell surface, they are key mediators in cellular events (cell-cell recognition, cell-matrix interactions). Interaction between such therapeutic sugar parts and cellular polysaccharides could generate interesting result in drugs like epothilone A. Based on this hypothesis, epothilone A glucoside (epothilone A 6-O-ß-D-glucoside) was further decorated by conjugating enzymatically galactose followed by sialic acids to generate epothilone A 7-O-ß-D-glucopyranosyl, 4'-O-α-D-galactoside i.e., lactosyl epothilone A (lac epoA) and two sialosides of epothilone A namely epothilone A 7-O-ß-D-glucopyranosyl, 4'-O-α-D-galactopyranosyl 3″-O-α-N-acetyl neuraminic acid and epothilone A 7-O-ß-D-glucopyranosyl, 4'-O-α-D-galactopyranosyl 6″-O-α-N-acetylneuraminic acid i.e., 3'sialyllactosyl epothilone A: 3'SL-epoA, and 6'sialyllactosyl epothilone A: 6'SL-epoA, respectively. These synthesized analogs were spectroscopically analyzed and elucidated, and biologically validated using HUVEC and HCT116 cancer cell lines.


Assuntos
Epotilonas , Células Endoteliais da Veia Umbilical Humana/metabolismo , Ácido Láctico/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Linhagem Celular Tumoral , Epotilonas/farmacocinética , Epotilonas/farmacologia , Humanos
10.
Appl Microbiol Biotechnol ; 100(23): 9917-9931, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27412463

RESUMO

Nargenicin A1, an antibacterial produced by Nocardia sp. CS682 (KCTC 11297BP), demonstrates effective activity against various Gram-positive bacteria. Hence, we attempted to enhance nargenicin A1 production by utilizing the cumulative effect of synthetic biology, metabolic engineering and statistical media optimization strategies. To facilitate the modular assembly of multiple genes for genetic engineering in Nocardia sp. CS682, we constructed a set of multi-monocistronic vectors, pNV18L1 and pNV18L2 containing hybrid promoter (derived from ermE* and promoter region of neo r ), ribosome binding sites (RBS), and restriction sites for cloning, so that each cloned gene was under its own promoter and RBS. The multi-monocistronic vector, pNV18L2 containing transcriptional terminator showed better efficiency in reporter gene assay. Thus, multiple genes involved in the biogenesis of pyrrole moiety (ngnN2, ngnN3, ngnN4, and ngnN5 from Nocardia sp. CS682), glucose utilization (glf and glk from Zymomonas mobilis), and malonyl-CoA synthesis (accA2 and accBE from Streptomyces coelicolor A3 (2)), were cloned in pNV18L2. Further statistical optimization of specific precursors (proline and glucose) and their feeding time led to ~84.9 mg/L nargenicin from Nocardia sp. GAP, which is ~24-fold higher than Nocardia sp. CS682 (without feeding). Furthermore, pikC from Streptomyces venezuelae was expressed to generate Nocardia sp. PikC. Nargenicin A1 acid was characterized as novel derivative of nargenicin A1 produced from Nocardia sp. PikC by mass spectrometry (MS) and nuclear magnetic resonance (NMR) analyses. We also performed comparative analysis of the anticancer and antibacterial activities of nargenicin A1 and nargenicin A1 acid, which showed a reduction in antibacterial potential for nargenicin A1 acid. Thus, the development of an efficient synthetic biological platform provided new avenues for enhancing or structurally diversifying nargenicin A1 by means of pathway designing and engineering.


Assuntos
Antibacterianos/metabolismo , Engenharia Metabólica , Redes e Vias Metabólicas/genética , Nocardia/genética , Nocardia/metabolismo , Biologia Sintética , Meios de Cultura/química , Expressão Gênica , Vetores Genéticos , Lactonas/metabolismo , Nocardia/crescimento & desenvolvimento , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
11.
Microb Cell Fact ; 14: 76, 2015 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-26051114

RESUMO

BACKGROUND: A multi-monocistronic synthetic vector was used to assemble multiple genes of a nucleotide diphosphate (NDP)-sugar biosynthetic pathway to construct robust genetic circuits for the production of valuable flavonoid glycosides in Escherichia coli. Characterized functional genes involved in the biosynthesis of uridine diphosphate (UDP)-glucose and thymidine diphosphate (TDP)-rhamnose from various microbial sources along with glucose facilitator diffusion protein (glf) and glucokinase (glk) from Zymomonas mobilis were assembled and overexpressed in a single synthetic multi-monocistronic operon. RESULTS: The newly generated NDP-sugars biosynthesis circuits along with regiospecific glycosyltransferases from plants were introduced in E. coli BL21 (DE3) to probe the bioconversion of fisetin, a medicinally important polyphenol produced by various plants. As a result, approximately 1.178 g of fisetin 3-O-glucoside and 1.026 g of fisetin 3-O-rhamnoside were produced in UDP-glucose and TDP-rhamnose biosynthesis systems respectively, after 48 h of incubation in 3 L fermentor while supplementing 0.9 g of fisetin. These yields of fisetin glycosides represent ~99% of bioconversion of exogenously supplemented fisetin. The systems were also found to be highly effective in bio-transforming other flavonols (quercetin, kaempferol, myricetin) into their respective glycosides, achieving over 95% substrate conversion. CONCLUSION: The construction of a synthetic expression vector for bacterial cell factory followed by subsequent re-direction of metabolic flux towards desirable products have always been revolutionized the biotechnological processes and technologies. This multi-monocistronic synthetic vector in a microbial platform is customizable to defined task and would certainly be useful for applications in producing and modifying such therapeutically valued plant secondary metabolites.


Assuntos
Escherichia coli/metabolismo , Flavonóis/metabolismo , Glicosídeos/metabolismo , Glicosiltransferases/genética
12.
Appl Environ Microbiol ; 80(23): 7235-43, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25239890

RESUMO

A UDP glucosyltransferase from Bacillus licheniformis was overexpressed, purified, and incubated with nucleotide diphosphate (NDP) d- and l-sugars to produce glucose, galactose, 2-deoxyglucose, viosamine, rhamnose, and fucose sugar-conjugated resveratrol glycosides. Significantly higher (90%) bioconversion of resveratrol was achieved with α-d-glucose as the sugar donor to produce four different glucosides of resveratrol: resveratrol 3-O-ß-d-glucoside, resveratrol 4'-O-ß-d-glucoside, resveratrol 3,5-O-ß-d-diglucoside, and resveratrol 3,5,4'-O-ß-d-triglucoside. The conversion rates and numbers of products formed were found to vary with the other NDP sugar donors. Resveratrol 3-O-ß-d-2-deoxyglucoside and resveratrol 3,5-O-ß-d-di-2-deoxyglucoside were found to be produced using TDP-2-deoxyglucose as a donor; however, the monoglycosides resveratrol 4'-O-ß-d-galactoside, resveratrol 4'-O-ß-d-viosaminoside, resveratrol 3-O-ß-l-rhamnoside, and resveratrol 3-O-ß-l-fucoside were produced from the respective sugar donors. Altogether, 10 diverse glycoside derivatives of the medically important resveratrol were generated, demonstrating the capacity of YjiC to produce structurally diverse resveratrol glycosides.


Assuntos
Bacillus/enzimologia , Glucuronosiltransferase/metabolismo , Glicosídeos/metabolismo , Estilbenos/metabolismo , Bacillus/genética , Carboidratos/análise , Clonagem Molecular , Citosol/química , Expressão Gênica , Glucuronosiltransferase/genética , Glucuronosiltransferase/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Resveratrol
13.
Glycoconj J ; 31(8): 563-72, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25069899

RESUMO

Mupirocin is a commercially available antibiotic that acts on bacterial isoleucyl-tRNA synthetase, thereby inhibiting protein synthesis and preventing bacterial infection. An in vitro glycosylation approach was applied to synthesize glycoside derivatives of mupirocin using different NDP-sugars and glycosyltransferase from Bacillus licheniformis. Ultra pressure liquid chromatography-photo diode array analyses of the reaction mixtures revealed the generation of product peak(s). The results were further supported by high-resolution quadruple time of flight electrospray ionization mass spectrometry analyses. The product purified from the reaction mixture with UDP-D-glucose was subjected to NMR analysis, and the structure was determined to be mupirocin 6-O-ß-D-glucoside. Other glycoside analogs of mupirocin were determined based on high-resolution mass analyses. Antibacterial activity assays against Staphylococcus aureus demonstrated complete loss of antibacterial activity after glucosylation of mupirocin at the 6-hydroxyl position.


Assuntos
Antibacterianos/metabolismo , Glicosiltransferases/metabolismo , Mupirocina/metabolismo , Administração Tópica , Antibacterianos/química , Antibacterianos/farmacologia , Biocatálise/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Glucosídeos/metabolismo , Glicoconjugados/metabolismo , Glicosilação/efeitos dos fármacos , Glicosiltransferases/isolamento & purificação , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Mupirocina/química , Mupirocina/farmacologia , Espectroscopia de Prótons por Ressonância Magnética , Espectrometria de Massas por Ionização por Electrospray , Fatores de Tempo
14.
Appl Environ Microbiol ; 79(21): 6833-8, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23974133

RESUMO

The glycosylation of five different flavonols, fisetin, quercetin, myricetin, kaempferol, and 3-hydroxyflavone, was achieved by applying YjiC. 3-Hydroxyflavone was selected as a probe for in vitro glycorandomization of all flavonols using diverse nucleotide diphosphate-d/l-sugars. This study unlocked the possibilities of the glycodiversification of flavonols and the generation of novel compounds as future therapeutics.


Assuntos
Descoberta de Drogas/métodos , Flavonoides/metabolismo , Glicosiltransferases/metabolismo , Engenharia Metabólica/métodos , Bacillus/enzimologia , Cromatografia Líquida de Alta Pressão , Escherichia coli , Flavonoides/química , Glicosilação , Estrutura Molecular , Açúcares de Nucleosídeo Difosfato/metabolismo
15.
Adv Sci (Weinh) ; 10(15): e2206901, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36994629

RESUMO

Practical applications of sulfurized polymer (SP) materials in Li-S batteries (LSBs) are often written off due to their low S content (≈35 wt%). Unlike conventional S8 /C composite cathodes, SP materials are shown to function as pseudocapacitors with an active carbon backbone using a comprehensive array of tools including in situ Raman and electrochemical impedance spectroscopy. Critical metric analysis of LSBs containing SP materials with an active carbon skeleton shows that SP cathodes with 35 wt% S are suitable for 350 Wh kg-1 target at the cell level if S loading >5 mg cm-2 , electrolyte-to-sulfur ratio <2 µL mg-1 , and negative-to-positive ratio <5 can be achieved. Although 3D current collectors can enable such high loadings, they often add excess mass decreasing the total capacity. An "active" carbon nanotube bucky sandwich current collector developed here offsets its excess weight by contributing to the electric double layer capacity. SP cathodes (35 wt% S) with ≈5.5 mg cm-2 of S loading (≈15.8 mg cm-2 of SP loading) yield a sulfur-level gravimetric capacity ≈1360 mAh gs -1 (≈690 mAh gs -1 ), electrode level capacity 200 mAh gelectrode -1 (100 mAh gelectrode -1 ), and areal capacity ≈7.8 mAh cm-2 (≈4.0 mAh cm-2 ) at 0.1C (1C) rate for ≈100 cycles at E/S ratio = 7 µL mg-1 .

16.
Carbohydr Polym ; 299: 120140, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36876763

RESUMO

Superabsorbent hydrogels (SAH) are crosslinked three-dimensional networks distinguished by their super capacity to stabilize a large quantity of water without dissolving. Such behavior enables them to engage in various applications. Cellulose and its derived nanocellulose can become SAHs as an appealing, versatile, and sustainable platform because of abundance, biodegradability, and renewability compared to petroleum-based materials. In this review, a synthetic strategy that reflects starting cellulosic resources to their associated synthons, crosslinking types, and synthetic controlling factors was highlighted. Representative examples of cellulose and nanocellulose SAH and an in-depth discussion of structure-absorption relationships were listed. Finally, various applications of cellulose and nanocellulose SAH, challenges and existing problems, and proposed future research pathways were listed.

17.
PLoS One ; 18(8): e0289707, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37540718

RESUMO

We have previously demonstrated that human liver-type phosphofructokinase 1 (PFK1) recruits other rate-determining enzymes in glucose metabolism to organize multienzyme metabolic assemblies, termed glucosomes, in human cells. However, it has remained largely elusive how glucosomes are reversibly assembled and disassembled to functionally regulate glucose metabolism and thus contribute to human cell biology. We developed a high-content quantitative high-throughput screening (qHTS) assay to identify regulatory mechanisms that control PFK1-mediated glucosome assemblies from stably transfected HeLa Tet-On cells. Initial qHTS with a library of pharmacologically active compounds directed following efforts to kinase-inhibitor enriched collections. Consequently, three compounds that were known to inhibit cyclin-dependent kinase 2, ribosomal protein S6 kinase and Aurora kinase A, respectively, were identified and further validated under high-resolution fluorescence single-cell microscopy. Subsequent knockdown studies using small-hairpin RNAs further confirmed an active role of Aurora kinase A on the formation of PFK1 assemblies in HeLa cells. Importantly, all the identified protein kinases here have been investigated as key signaling nodes of one specific cascade that controls cell cycle progression in human cells. Collectively, our qHTS approaches unravel a cell cycle-associated signaling network that regulates the formation of PFK1-mediated glucosome assembly in human cells.


Assuntos
Aurora Quinase A , Ensaios de Triagem em Larga Escala , Humanos , Células HeLa , Ciclo Celular , Glucose/metabolismo
18.
Methods Mol Biol ; 2487: 15-26, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35687227

RESUMO

Fluorescence live-cell imaging that has contributed to our understanding of cell biology is now at the frontline of studying quantitative biochemistry in a cell. Particularly, technological advancements of fluorescence live-cell imaging and associated strategies in recent years have allowed us to discover various subcellular macromolecular assemblies in living human cells. Here we describe how real-time dynamics of a multienzyme metabolic assembly, the "glucosome," that is responsible for regulating glucose flux at subcellular levels, has been investigated in both 2- and 3-dimensional space of single human cells. We envision that such multi-dimensional fluorescence live-cell imaging will continue to revolutionize our understanding of how intracellular metabolic pathways and their network are functionally orchestrated at single-cell levels.


Assuntos
Glucose , Imageamento Tridimensional , Glucose/metabolismo , Humanos , Microscopia de Fluorescência/métodos
19.
Carbohydr Polym ; 289: 119408, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35483831

RESUMO

The study evaluated the effect of cryogrinding, a relatively new, cost-effective, and sustainable mechanical treatment method, on physicochemical properties of two different micronaire (3.6- and 5.3-) cotton fiber cellulose. Native (type I), mercerized (type II), and acidulated cellulose were subjected to cryogrinding for 48 and 96 min, and their physicochemical properties were investigated. The results demonstrated that cryogrinding resulted in partial amorphization of native and mercerized celluloses, particle size decrease, and a slight reduction of T50%. Importantly, degree of polymerization (DP) of native cellulose reduced significantly: more than two-fold after 12 cycles and more than three-fold after 24 cycles of cryogrinding. No difference in properties was found between 3.6- and 5.3-micronaire cellulose. Advantageous impacts of cryogrinding found in this work will help signify the potential of this technique in cellulose processing and enable the identification of areas for future development.


Assuntos
Celulose , Fibra de Algodão , Celulose/química , Polimerização
20.
ACS Appl Energy Mater ; 5(10): 11964-11969, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36311467

RESUMO

Magnesium batteries have attracted great attention as an alternative to Li-ion batteries but still suffer from limited choice of positive electrode materials. V2O5 exhibits high theoretical capacities, but previous studies have been mostly limited to α-V2O5. Herein, we report on the ß-V2O5 polymorph as a Mg intercalation electrode. The structural changes associated with the Mg2+ (de-) intercalation were analyzed by a combination of several characterization techniques: in situ high resolution X-ray diffraction, scanning transmission electron microscopy, electron energy-loss spectroscopy, and X-ray absorption spectroscopy. The reversible capacity reached 361 mAh g-1, the highest value found at room temperature for V2O5 polymorphs.

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