Base de dados : MEDLINE
Pesquisa : D09.301.915.400 [Categoria DeCS]
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[PMID]:28886200
[Au] Autor:Zhang C; Acosta-Sampson L; Yu VY; Cate JHD
[Ad] Endereço:Department of Life Science, Tsinghua University, Beijing, China.
[Ti] Título:Screening of transporters to improve xylodextrin utilization in the yeast Saccharomyces cerevisiae.
[So] Source:PLoS One;12(9):e0184730, 2017.
[Is] ISSN:1932-6203
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The economic production of cellulosic biofuel requires efficient and full utilization of all abundant carbohydrates naturally released from plant biomass by enzyme cocktails. Recently, we reconstituted the Neurospora crassa xylodextrin transport and consumption system in Saccharomyces cerevisiae, enabling growth of yeast on xylodextrins aerobically. However, the consumption rate of xylodextrin requires improvement for industrial applications, including consumption in anaerobic conditions. As a first step in this improvement, we report analysis of orthologues of the N. crassa transporters CDT-1 and CDT-2. Transporter ST16 from Trichoderma virens enables faster aerobic growth of S. cerevisiae on xylodextrins compared to CDT-2. ST16 is a xylodextrin-specific transporter, and the xylobiose transport activity of ST16 is not inhibited by cellobiose. Other transporters identified in the screen also enable growth on xylodextrins including xylotriose. Taken together, these results indicate that multiple transporters might prove useful to improve xylodextrin utilization in S. cerevisiae. Efforts to use directed evolution to improve ST16 from a chromosomally-integrated copy were not successful, due to background growth of yeast on other carbon sources present in the selection medium. Future experiments will require increasing the baseline growth rate of the yeast population on xylodextrins, to ensure that the selective pressure exerted on xylodextrin transport can lead to isolation of improved xylodextrin transporters.
[Mh] Termos MeSH primário: Dextrinas/metabolismo
Saccharomyces cerevisiae/metabolismo
[Mh] Termos MeSH secundário: Celobiose/metabolismo
Celulose/metabolismo
Neurospora crassa/metabolismo
Saccharomyces cerevisiae/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 16462-44-5 (Cellobiose); 9004-34-6 (Cellulose)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171016
[Lr] Data última revisão:
171016
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170909
[St] Status:MEDLINE
[do] DOI:10.1371/journal.pone.0184730


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[PMID]:28802003
[Au] Autor:Gandini C; Tarraran L; Kalemasi D; Pessione E; Mazzoli R
[Ad] Endereço:Department of Life Sciences and Systems Biology, Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, University of Turin, Torino, Italy.
[Ti] Título:Recombinant Lactococcus lactis for efficient conversion of cellodextrins into L-lactic acid.
[So] Source:Biotechnol Bioeng;114(12):2807-2817, 2017 Dec.
[Is] ISSN:1097-0290
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Lactic acid bacteria (LAB) are among the most interesting organisms for industrial processes with a long history of application as food starters and biocontrol agents, and an underexploited potential for biorefineries converting biomass into high-value compounds. Lactic acid (LA), their main fermentation product, is among the most requested chemicals owing to its broad range of applications. Notably, LA polymers, that is, polylactides, have high potential as biodegradable substitutes of fossil-derived plastics. However, LA production by LAB fermentation is currently too expensive for polylactide to be cost-competitive with traditional plastics. LAB have complex nutritional requirements and cannot ferment inexpensive substrates such as cellulose. Metabolic engineering could help reduce such nutritional requirements and enable LAB to directly ferment low-cost polysaccharides. Here, we engineered a Lactococcus lactis strain which constitutively secretes a ß-glucosidase and an endoglucanase. The recombinant strain can grow on cellooligosaccharides up to at least cellooctaose and efficiently metabolizes them to L-LA in single-step fermentation. This is the first report of a LAB able to directly metabolize cellooligosaccharides longer that cellohexaose and a significant step toward cost-sustainable consolidated bioprocessing of cellulose into optically pure LA.
[Mh] Termos MeSH primário: Celulose/análogos & derivados
Dextrinas/metabolismo
Melhoramento Genético/métodos
Ácido Láctico/biossíntese
Lactococcus lactis/genética
Lactococcus lactis/metabolismo
Proteínas Recombinantes/metabolismo
Recombinação Genética/genética
[Mh] Termos MeSH secundário: Celulose/genética
Celulose/metabolismo
Dextrinas/genética
Ácido Láctico/isolamento & purificação
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 0 (Recombinant Proteins); 33X04XA5AT (Lactic Acid); 9004-34-6 (Cellulose); 9061-30-7 (cellodextrin)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171113
[Lr] Data última revisão:
171113
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170813
[St] Status:MEDLINE
[do] DOI:10.1002/bit.26400


  3 / 871 MEDLINE  
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[PMID]:28335503
[Au] Autor:Jicsinszky L; Caporaso M; Calcio Gaudino E; Giovannoli C; Cravotto G
[Ad] Endereço:Department of Drug Science and Technology, University of Turin, Via P. Giuria 7, 10125 Turin, Italy. ljicsinszky@gmail.com.
[Ti] Título:Synthesis of Randomly Substituted Anionic Cyclodextrins in Ball Milling.
[So] Source:Molecules;22(3), 2017 Mar 19.
[Is] ISSN:1420-3049
[Cp] País de publicação:Switzerland
[La] Idioma:eng
[Ab] Resumo:A number of influencing factors mean that the random substitution of cyclodextrins (CD) in solution is difficult to reproduce. Reaction assembly in mechanochemistry reduces the number of these factors. However, lack of water can improve the reaction outcomes by minimizing the reagent's hydrolysis. High-energy ball milling is an efficient, green and simple method for one-step reactions and usually reduces degradation and byproduct formation. Anionic CD derivatives have successfully been synthesized in the solid state, using a planetary ball mill. Comparison with solution reactions, the solvent-free conditions strongly reduced the reagent hydrolysis and resulted in products of higher degree of substitution (DS) with more homogeneous DS distribution. The synthesis of anionic CD derivatives can be effectively performed under mechanochemical activation without significant changes to the substitution pattern but the DS distributions were considerably different from the products of solution syntheses.
[Mh] Termos MeSH primário: Ciclodextrinas/química
Dextrinas/síntese química
[Mh] Termos MeSH secundário: Ânions/síntese química
Ânions/química
Dextrinas/química
Química Verde
Hidrólise
Solventes
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Anions); 0 (Cyclodextrins); 0 (Dextrins); 0 (Solvents)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170508
[Lr] Data última revisão:
170508
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170325
[St] Status:MEDLINE


  4 / 871 MEDLINE  
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[PMID]:28118504
[Au] Autor:Nelson CE; Rogowski A; Morland C; Wilhide JA; Gilbert HJ; Gardner JG
[Ad] Endereço:Department of Biological Sciences, University of Maryland - Baltimore County, Baltimore, Maryland, USA.
[Ti] Título:Systems analysis in Cellvibrio japonicus resolves predicted redundancy of ß-glucosidases and determines essential physiological functions.
[So] Source:Mol Microbiol;104(2):294-305, 2017 Apr.
[Is] ISSN:1365-2958
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:Degradation of polysaccharides forms an essential arc in the carbon cycle, provides a percentage of our daily caloric intake, and is a major driver in the renewable chemical industry. Microorganisms proficient at degrading insoluble polysaccharides possess large numbers of carbohydrate active enzymes (CAZymes), many of which have been categorized as functionally redundant. Here we present data that suggests that CAZymes that have overlapping enzymatic activities can have unique, non-overlapping biological functions in the cell. Our comprehensive study to understand cellodextrin utilization in the soil saprophyte Cellvibrio japonicus found that only one of four predicted ß-glucosidases is required in a physiological context. Gene deletion analysis indicated that only the cel3B gene product is essential for efficient cellodextrin utilization in C. japonicus and is constitutively expressed at high levels. Interestingly, expression of individual ß-glucosidases in Escherichia coli K-12 enabled this non-cellulolytic bacterium to be fully capable of using cellobiose as a sole carbon source. Furthermore, enzyme kinetic studies indicated that the Cel3A enzyme is significantly more active than the Cel3B enzyme on the oligosaccharides but not disaccharides. Our approach for parsing related CAZymes to determine actual physiological roles in the cell can be applied to other polysaccharide-degradation systems.
[Mh] Termos MeSH primário: Metabolismo dos Carboidratos/fisiologia
Celulases/fisiologia
Cellvibrio/fisiologia
[Mh] Termos MeSH secundário: Celulases/metabolismo
Celulose/análogos & derivados
Celulose/metabolismo
Dextrinas/metabolismo
Dissacarídeos/metabolismo
Enzimas
Escherichia coli/genética
Cinética
Polissacarídeos/metabolismo
Análise de Sistemas
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 0 (Disaccharides); 0 (Enzymes); 0 (Polysaccharides); 9004-34-6 (Cellulose); 9061-30-7 (cellodextrin); EC 3.2.1.- (Cellulases)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:170921
[Lr] Data última revisão:
170921
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170125
[St] Status:MEDLINE
[do] DOI:10.1111/mmi.13625


  5 / 871 MEDLINE  
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[PMID]:28115383
[Au] Autor:Keung HY; Li TK; Sham LT; Cheung MK; Cheung PC; Kwan HS
[Ad] Endereço:School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR.
[Ti] Título:Mechanistic Study of Utilization of Water-Insoluble Saccharomyces cerevisiae Glucans by Bifidobacterium breve Strain JCM1192.
[So] Source:Appl Environ Microbiol;83(7), 2017 Apr 01.
[Is] ISSN:1098-5336
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Bifidobacteria exert beneficial effects on hosts and are extensively used as probiotics. However, due to the genetic inaccessibility of these bacteria, little is known about their mechanisms of carbohydrate utilization and regulation. strain JCM1192 can grow on water-insoluble yeast ( ) cell wall glucans (YCWG), which were recently considered as potential prebiotics. According to the results of H nuclear magnetic resonance (NMR) spectrometry, the YCWG were composed of highly branched (1→3,1→6)-ß-glucans and (1→4,1→6)-α-glucans. Although the YCWG were composed of 78.3% ß-glucans and 21.7% α-glucans, only α-glucans were consumed by the strain. The ABC transporter ( ) and pullulanase ( ) genes were transcriptionally upregulated in the metabolism of insoluble yeast glucans, suggesting their potential involvement in the process. A nonsense mutation identified in the gene encoding an ABC transporter ATP-binding protein (MalK) led to growth failure of an ethyl methanesulfonate-generated mutant with yeast glucans. Coculture of the wild-type strain and the mutant showed that this protein was responsible for the import of yeast glucans or their breakdown products, rather than the export of α-glucan-catabolizing enzymes. Further characterization of the carbohydrate utilization of the mutant and three of its revertants indicated that this mutation was pleiotropic: the mutant could not grow with maltose, glycogen, dextrin, raffinose, cellobiose, melibiose, or turanose. We propose that insoluble yeast α-glucans are hydrolyzed by extracellular pullulanase into maltose and/or maltooligosaccharides, which are then transported into the cell by the ABC transport system composed of MalEFG1 and MalK. The mechanism elucidated here will facilitate the development of and water-insoluble yeast glucans as novel synbiotics. In general, strains are genetically intractable. Coupling classic forward genetics with next-generation sequencing, here we identified an ABC transporter ATP-binding protein (MalK) responsible for the import of insoluble yeast glucan breakdown products by JCM1192. We demonstrated the pleiotropic effects of the ABC transporter ATP-binding protein in maltose/maltooligosaccharide, raffinose, cellobiose, melibiose, and turanose transport. With the addition of transcriptional analysis, we propose that insoluble yeast glucans are broken down by extracellular pullulanase into maltose and/or maltooligosaccharides, which are then transported into the cell by the ABC transport system composed of MalEFG1 and MalK. The mechanism elucidated here will facilitate the development of and water-insoluble yeast glucans as novel synbiotics.
[Mh] Termos MeSH primário: Bifidobacterium breve/metabolismo
Glucanos/metabolismo
Saccharomyces cerevisiae/química
[Mh] Termos MeSH secundário: Transportadores de Cassetes de Ligação de ATP/genética
Transportadores de Cassetes de Ligação de ATP/metabolismo
Proteínas de Bactérias/genética
Proteínas de Bactérias/metabolismo
Bifidobacterium breve/efeitos dos fármacos
Bifidobacterium breve/genética
Bifidobacterium breve/crescimento & desenvolvimento
Parede Celular/química
Parede Celular/metabolismo
Dextrinas/farmacologia
Glicogênio/farmacologia
Glicosídeo Hidrolases/genética
Glicosídeo Hidrolases/metabolismo
Hidrólise
Maltose/metabolismo
Maltose/farmacologia
Mutação
Solubilidade
Simbióticos
Água
beta-Glucanas/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Dextrins); 0 (Glucans); 0 (MalK protein, Bacteria); 0 (beta-Glucans); 059QF0KO0R (Water); 69-79-4 (Maltose); 9005-79-2 (Glycogen); EC 3.2.1.- (Glycoside Hydrolases); EC 3.2.1.41 (pullulanase)
[Em] Mês de entrada:1711
[Cu] Atualização por classe:171109
[Lr] Data última revisão:
171109
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170125
[St] Status:MEDLINE


  6 / 871 MEDLINE  
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[PMID]:28100603
[Au] Autor:Kondo T; Handa K; Genda T; Hino S; Hamaguchi N; Morita T
[Ad] Endereço:Graduate School of Science and Technology, and.
[Ti] Título:Digestion-Resistant Dextrin Derivatives Are Moderately Digested in the Small Intestine and Contribute More to Energy Production Than Predicted from Large-Bowel Fermentation in Rats.
[So] Source:J Nutr;147(3):330-336, 2017 Mar.
[Is] ISSN:1541-6100
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Digestion-resistant dextrin derivatives (DRDDs), including resistant maltodextrin (RM), polydextrose, and resistant glucan (RG), have been developed as low-energy foods. However, data on the resistance of DRDDs to small-intestinal digestion are scarce. We sought to determine the site and extent of DRDD breakdown in the rat intestine and to predict its energy contributions. In vitro small-intestinal resistance of DRDDs was evaluated by the AOAC method for dietary fiber measurement and by artificial digestion with the use of pancreatic α-amylase and brush-boarder membrane vesicles. In vivo small-intestinal resistance of DRDDs was determined from the feces of male ileorectostomized Sprague-Dawley rats fed a control diet or a diet containing one of the DRDDs at 50 g/kg for 9 d (period 1) and then for 10 d (period 2), during which they received 1 g neomycin/L in their drinking water. Separately, male Sprague-Dawley rats were fed the same diets for 4 wk, and the whole-gut recoveries of DRDDs were determined from feces at days 8-10. Small-intestinal resistances determined in vitro by artificial digestion (RM: 70%; polydextrose: 67%; RG: 69%) were lower than those measured by the AOAC method (RM: 92%; polydextrose: 80%; RG: 82%). In the ileorectostomized rats, fecal dry-matter excretions were consistently greater in the DRDDs than in the control. The small-intestinal resistances of the DRDDs were 68%, 58%, and 62% in period 1 and 66%, 61%, and 67% during period 2 for RM, polydextrose, and RG, respectively. The resistances did not differ among the DRDDs at either time. In the normal rats, food intakes and body weight gains did not differ among the groups. The whole-gut recovery of RM (13%) was lower than that of polydextrose (33%) and RG (29%), which did not differ. DRDDs were more digestible in the rat small intestine than the AOAC method. The energy contribution from small-intestine digestibility, not just large-bowel fermentability, must be considered in determining the energy contribution of DRDDs. Whether humans respond similarly needs to be tested.
[Mh] Termos MeSH primário: Dextrinas/química
Fibras na Dieta/metabolismo
Digestão/fisiologia
Intestino Grosso/fisiologia
Intestino Delgado/fisiologia
[Mh] Termos MeSH secundário: Ração Animal/análise
Animais
Dextrinas/metabolismo
Dieta/veterinária
Metabolismo Energético
Fezes/química
Fermentação
Masculino
Ratos
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 0 (Dietary Fiber)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170120
[St] Status:MEDLINE
[do] DOI:10.3945/jn.116.239855


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[PMID]:28039555
[Au] Autor:Lin L; Chen Y; Li J; Wang S; Sun W; Tian C
[Ad] Endereço:Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
[Ti] Título:Disruption of non-anchored cell wall protein NCW-1 promotes cellulase production by increasing cellobiose uptake in Neurospora crassa.
[So] Source:Biotechnol Lett;39(4):545-551, 2017 Apr.
[Is] ISSN:1573-6776
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:OBJECTIVES: To elucidate the mechanism of cellulase signal transduction in filamentous fungi including the components of the cellulase induction pathway. RESULTS: Neurospora crassa ncw-1 encodes a non-anchored cell wall protein. The absence of ncw-1 increased cellulase gene expression and this is not due to relieving carbon catabolite repression mediated by the cre-1 pathway. A mutant lacking genes encoding both three major ß-glucosidase enzymes and NCW-1 (Δ3ßGΔncw-1) was constructed. Transcriptome analysis of the quadruple mutant demonstrated enhanced expression of cellodextrin transporters after ncw-1 deletion, indicating that ncw-1 affects cellulase expression and production by inhibiting the uptake of the cellodextrin. CONCLUSIONS: NCW-1 is a novel component that plays a critical role in the cellulase induction signaling pathway.
[Mh] Termos MeSH primário: Celobiose/metabolismo
Celulase/metabolismo
Proteínas Fúngicas/metabolismo
Proteínas de Membrana Transportadoras/metabolismo
Neurospora crassa/enzimologia
Transdução de Sinais
[Mh] Termos MeSH secundário: Parede Celular/metabolismo
Celulase/genética
Celulose/análogos & derivados
Celulose/metabolismo
Dextrinas/metabolismo
Proteínas Fúngicas/genética
Regulação Fúngica da Expressão Gênica
Proteínas de Membrana Transportadoras/genética
Neurospora crassa/genética
beta-Glucosidase/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 0 (Fungal Proteins); 0 (Membrane Transport Proteins); 16462-44-5 (Cellobiose); 9004-34-6 (Cellulose); 9061-30-7 (cellodextrin); EC 3.2.1.21 (beta-Glucosidase); EC 3.2.1.4 (Cellulase)
[Em] Mês de entrada:1704
[Cu] Atualização por classe:170412
[Lr] Data última revisão:
170412
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170101
[St] Status:MEDLINE
[do] DOI:10.1007/s10529-016-2274-1


  8 / 871 MEDLINE  
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[PMID]:27913241
[Au] Autor:Kadota K; Senda A; Tagishi H; Ayorinde JO; Tozuka Y
[Ad] Endereço:Laboratory of Formulation Design and Pharmaceutical Technology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. Electronic address: kadota@gly.oups.ac.jp.
[Ti] Título:Evaluation of highly branched cyclic dextrin in inhalable particles of combined antibiotics for the pulmonary delivery of anti-tuberculosis drugs.
[So] Source:Int J Pharm;517(1-2):8-18, 2017 Jan 30.
[Is] ISSN:1873-3476
[Cp] País de publicação:Netherlands
[La] Idioma:eng
[Ab] Resumo:This work aims to identify a suitable formulation for the pulmonary delivery of combinations of inhalational drugs using highly branched cyclic dextrin (HBCD) macromolecules. We compared the effectiveness between powders prepared from HBCD with those prepared from five alternative excipients (lactose, maltose, sucrose, ß-cyclodextrin and methyl ß-cyclodextrin) in the pulmonary delivery of a single-dosage form of two anti-tuberculosis drugs (isoniazid and rifampicin). Fine particles of untreated active pharmaceutical ingredients (APIs) and combination products using excipients were prepared by spray drying. Rifampicin, a hydrophobic compound, was dissolved in ethanol, whereas isoniazid, a hydrophilic compound combined with either HBCD or an alternative excipient was dissolved in water. This was followed by the preparation of the spray-dried particle formulations (SDPs). The SDPs were characterised in terms of particle size, surface morphology, drug content, specific surface area, powder X-ray diffraction and inhalational properties. The addition of either an excipient or HBCD decreased API particle sizes, producing submicron-size particles. Surface morphology examination using scanning electron microscopy revealed API SDPs to be cylindrical and non-wrinkled. However, API-excipient SDPs were wrinkled and rough. Only HBCD SDPs were porous and non-aggregating, thereby suggesting superior aerodynamic properties and suitability for pulmonary delivery of these particles. HBCD formulations had the highest drug content in terms of both isoniazid (97.5%) and rifampicin (92.3%). Larger surface areas were obtained for SDPs of HBCD than those of other sugars. Regarding inhalational properties, HBCD formulations had higher emitted dose and fine-particle fractions than formulations of all other sugars tested. Our results confirm the feasibility of the formulation of hydrophilic and hydrophobic drug substances into a single-dosage preparation for pulmonary delivery using HBCD as an excipient.
[Mh] Termos MeSH primário: Antibióticos Antituberculose/administração & dosagem
Dextrinas/química
Portadores de Fármacos/química
Isoniazida/administração & dosagem
Pulmão/metabolismo
Rifampina/administração & dosagem
[Mh] Termos MeSH secundário: Administração por Inalação
Antibióticos Antituberculose/química
Antibióticos Antituberculose/farmacocinética
Combinação de Medicamentos
Desenho de Drogas
Excipientes/química
Isoniazida/química
Isoniazida/farmacocinética
Modelos Teóricos
Tamanho da Partícula
Porosidade
Rifampina/química
Rifampina/farmacocinética
Relação Estrutura-Atividade
Propriedades de Superfície
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Antibiotics, Antitubercular); 0 (Dextrins); 0 (Drug Carriers); 0 (Drug Combinations); 0 (Excipients); V83O1VOZ8L (Isoniazid); VJT6J7R4TR (Rifampin)
[Em] Mês de entrada:1706
[Cu] Atualização por classe:170627
[Lr] Data última revisão:
170627
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161204
[St] Status:MEDLINE


  9 / 871 MEDLINE  
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[PMID]:27822737
[Au] Autor:Zhang C; Wang X; Zhang W; Zhao Y; Lu X
[Ad] Endereço:State Key Laboratory of Microbial Technology, College of Life Science, Shandong University, Jinan, 250100, China.
[Ti] Título:Expression and characterization of a glucose-tolerant ß-1,4-glucosidase with wide substrate specificity from Cytophaga hutchinsonii.
[So] Source:Appl Microbiol Biotechnol;101(5):1919-1926, 2017 Mar.
[Is] ISSN:1432-0614
[Cp] País de publicação:Germany
[La] Idioma:eng
[Ab] Resumo:Cytophaga hutchinsonii is a gram-negative bacterium that can efficiently degrade crystalline cellulose by a novel strategy without cell-free cellulases or cellulosomes. Genomic analysis implied that C. hutchinsonii had endoglucanases and ß-glucosidases but no exoglucanases which could processively digest cellulose and produce cellobiose. In this study, BglA was functionally expressed in Escherichia coli and found to be a ß-glucosidase with wide substrate specificity. It can hydrolyze pNPG, pNPC, cellobiose, and cellodextrins. Moreover, unlike most ß-glucosidases whose activity greatly decreases with increasing length of the substrate chains, BglA has similar activity on cellobiose and larger cellodextrins. The K values of BglA on cellobiose, cellotriose, and cellotetraose were calculated to be 4.8 × 10 , 5.6 × 10 , and 5.3 × 10 mol/l, respectively. These properties give BglA a great advantage to cooperate with endoglucanases in C. hutchinsonii in cellulose degradation. We proposed that C. hutchinsonii could utilize a simple cellulase system which consists of endoglucanases and ß-glucosidases to completely digest amorphous cellulose into glucose. Moreover, BglA was also found to be highly tolerant to glucose as it retained 40 % activity when the concentration of glucose was 100 times higher than that of the substrate, showing potential application in the bioenergy industry.
[Mh] Termos MeSH primário: Celulose/metabolismo
Cytophaga/enzimologia
Escherichia coli/metabolismo
beta-Glucosidase/genética
beta-Glucosidase/metabolismo
[Mh] Termos MeSH secundário: Celobiose/biossíntese
Celulose/análogos & derivados
Cytophaga/metabolismo
Dextrinas/metabolismo
Escherichia coli/genética
Glucose/metabolismo
Engenharia de Proteínas
Proteínas Recombinantes/genética
Proteínas Recombinantes/metabolismo
Especificidade por Substrato
Tetroses/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Dextrins); 0 (Recombinant Proteins); 0 (Tetroses); 16462-44-5 (Cellobiose); 38819-01-1 (cellotetraose); 9004-34-6 (Cellulose); 9061-30-7 (cellodextrin); EC 3.2.1.21 (beta-Glucosidase); IY9XDZ35W2 (Glucose)
[Em] Mês de entrada:1702
[Cu] Atualização por classe:170227
[Lr] Data última revisão:
170227
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161109
[St] Status:MEDLINE
[do] DOI:10.1007/s00253-016-7927-4


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Fotocópia
[PMID]:27680987
[Au] Autor:McRorie JW; Chey WD
[Ad] Endereço:Global Clinical Sciences, Procter & Gamble, Mason Business Center, 8700 Mason-Montgomery Road, Mason, OH, 45040, USA. mcrorie.jw@pg.com.
[Ti] Título:Fermented Fiber Supplements Are No Better Than Placebo for a Laxative Effect.
[So] Source:Dig Dis Sci;61(11):3140-3146, 2016 Nov.
[Is] ISSN:1573-2568
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:BACKGROUND: Misconceptions about the effects of dietary fiber and 'functional' fiber on stool parameters and constipation persist in the literature. METHODS: A comprehensive literature review was conducted with the use of the Scopus and PubMed scientific databases to identify and objectively assess well-controlled clinical studies that evaluated the effects of fiber on stool parameters and constipation. RESULTS: The totality of well-controlled randomized clinical studies show that, to exert a laxative effect, fiber must: (1) resist fermentation to remain intact throughout the large bowel and present in stool, and (2) significantly increase stool water content and stool output, resulting in soft/bulky/easy-to-pass stools. Poorly fermented insoluble fiber (e.g., wheat bran) remains as discreet particles which can mechanically irritate the gut mucosa, stimulating water & mucous secretion if the particles are sufficiently large/coarse. For soluble fibers, some have no effect on viscosity (e.g., inulin, wheat dextrin) while others form high viscosity gels (e.g., ß-glucan, psyllium). If the soluble fiber is readily fermented, whether non-viscous or gel-forming, it has no effect on stool output or stool water content, and has no laxative effect. In contrast, a non-fermented, gel-forming soluble fiber (e.g., psyllium) retains its gelled nature and high water-holding capacity throughout the large bowel, resulting in soft/bulky/easy-to-pass stools. CONCLUSION: When considering a recommendation for a fiber supplement regimen to treat and/or prevent constipation, it is important to consider which fibers have the physical characteristics to exert a laxative effect, and which fiber supplements have rigorous clinical evidence of a significant benefit in patients with constipation.
[Mh] Termos MeSH primário: Constipação Intestinal/prevenção & controle
Fibras na Dieta/uso terapêutico
Fermentação
Laxantes/uso terapêutico
[Mh] Termos MeSH secundário: Constipação Intestinal/tratamento farmacológico
Dextrinas/uso terapêutico
Suplementos Nutricionais
Glucanos/uso terapêutico
Seres Humanos
Inulina/uso terapêutico
Psyllium/uso terapêutico
beta-Glucanas/uso terapêutico
[Pt] Tipo de publicação:JOURNAL ARTICLE; REVIEW
[Nm] Nome de substância:
0 (Dextrins); 0 (Dietary Fiber); 0 (Glucans); 0 (Laxatives); 0 (beta-Glucans); 8063-16-9 (Psyllium); 9005-80-5 (Inulin); VH2XOU12IE (polydextrose)
[Em] Mês de entrada:1707
[Cu] Atualização por classe:171116
[Lr] Data última revisão:
171116
[Sb] Subgrupo de revista:AIM; IM
[Da] Data de entrada para processamento:160930
[St] Status:MEDLINE



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