Articoli di riviste: "Fucose"

1

Becerra, Jimmy E., María J. Yebra e Vicente Monedero. "An l-Fucose Operon in the Probiotic Lactobacillus rhamnosus GG Is Involved in Adaptation to Gastrointestinal Conditions". Applied and Environmental Microbiology 81, n. 11 (27 marzo 2015): 3880–88. http://dx.doi.org/10.1128/aem.00260-15.

Testo completo

Abstract (sommario):

ABSTRACTl-Fucose is a sugar present in human secretions as part of human milk oligosaccharides, mucins, and other glycoconjugates in the intestinal epithelium. The genome of the probioticLactobacillus rhamnosusGG (LGG) carries a gene cluster encoding a putativel-fucose permease (fucP),l-fucose catabolic pathway (fucI,fucK,fucU, andfucA), and a transcriptional regulator (fucR). The metabolism ofl-fucose in LGG results in 1,2-propanediol production, and theirfucIandfucPmutants displayed a severe and mild growth defect onl-fucose, respectively. Transcriptional analysis revealed that thefucgenes are induced byl-fucose and subject to a strong carbon catabolite repression effect. This induction was triggered by FucR, which acted as a transcriptional activator necessary for growth onl-fucose. LGG utilized fucosyl-α1,3-N-acetylglucosamine and contrarily to other lactobacilli, the presence offucgenes allowed this strain to use thel-fucose moiety. InfucIandfucRmutants, but not infucPmutant,l-fucose was not metabolized and it was excreted to the medium during growth on fucosyl-α1,3-N-acetylglucosamine. Thefucgenes were induced by this fucosyl-disaccharide in the wild type and thefucPmutant but not in afucImutant, showing that FucP does not participate in the regulation offucgenes and thatl-fucose metabolism is needed for FucR activation. Thel-fucose operon characterized here constitutes a new example of the many factors found in LGG that allow this strain to adapt to the gastrointestinal conditions.

Gli stili APA, Harvard, Vancouver, ISO e altri

2

Liu, Xixi, Zhexian Zhang, Hui Mao, Pin Wang, Zhichuang Zuo, Li Gao, Xiang Shi, Ronghua Yin, Na Gao e Jinhua Zhao. "Characterization of the Hydrolysis Kinetics of Fucosylated Glycosaminoglycan in Mild Acid and Structures of the Resulting Oligosaccharides". Marine Drugs 18, n. 6 (29 maggio 2020): 286. http://dx.doi.org/10.3390/md18060286.

Testo completo

Abstract (sommario):

Mild acid hydrolysis is a common method for the structure analysis of fucosylated glycosaminoglycan (FG). In this work, the effects of acid hydrolysis on the structure of FG from S. variegatus (SvFG) and the reaction characteristic were systemically studied. The degree of defucosylation (DF) and molecular weights (Mw) of partial fucosylated glycosaminoglycans (pFs) were monitored by 1H NMR and size-exclusion chromatography, respectively. The kinetic plots of DF, degree of desulfation (DS) from fucose branches, and degree of hydrolysis (DH) of the backbone are exponentially increased with time, indicating that acid hydrolysis of SvFG followed a first-order kinetics. The kinetic rate constants kDF, kDS, and kDH were determined to be 0.0223 h-1, 0.0041 h-1, and 0.0005 h-1, respectively. The structure of the released sulfated fucose branches (FucS) from SvFG and HfFG (FG from H. fuscopunctata) was characterized by 1D/2D NMR spectroscopy, suggesting the presence of six types of fucose: α/β Fuc2S4S, Fuc3S4S, Fuc3S, Fuc4S, Fuc2S, and Fuc. The Fuc3S4S was more susceptible to acid than Fuc2S4S, and that the sulfate ester in position of O-2 and O-3 than in O-4 of fucose. The structure characteristic of pF18 indicated the cleavage of backbone glycosidic bonds. The APTT prolonged activity reduced with the decrease of the DF and Mw of the pFs, and became insignificant when its DF was 87% with Mw of 3.5 kDa.

Gli stili APA, Harvard, Vancouver, ISO e altri

3

Pérez-Escalante, Emmanuel, Luis Guillermo González-Olivares, Araceli Castañeda-Ovando, Alma Elizabeth Cruz-Guerrero, John F. Trant, Wendolyne López-Orozco, Luis Humberto Mendoza-Huizar e Sergio Alatorre-Santamaría. "An In Silico Approach to Enzymatic Synthesis of Fucooligosaccharides Using α-l-Fucosidase from Thermotoga maritima". Chemistry Proceedings 3, n. 1 (14 novembre 2020): 10. http://dx.doi.org/10.3390/ecsoc-24-08303.

Testo completo

Abstract (sommario):

Fucooligosaccharides comprise the primary group of human milk oligosaccharides. Due to their beneficial properties, a series of synthetic methods have been proposed to obtain them. Enzymatic methods show great promise, and α-l-fucosidase from Thermotoga maritima has emerged as a powerful catalyst for their production. Nonetheless, the enzyme’s limited substrate scope has delayed its wider application. The present work aims to compare the relative reactivity of fucose, pNP-fucose, and ethyl-fucose, while also exploring the molecular interactions of these fucosyl-donors with the enzyme through a combination DFT and docking analysis. The HOMO-LUMO band gaps range from −7.14571 to −4.24429 eV, with α/β-pNP-fucose and α-fucose being the three most reactive compounds. Moderate association energies between −6.4 to −5.5 kcal·mol−1 were found in the docking analysis, with α-pNP-fucose and both anomers of ethyl-fucose demonstrating the poorest affinity. In the case of α/β-lactose affinity to the β-fucose/enzyme complex, no significant differences were shown. We conclude that the best fucosyl-donors for transfucosylation are those that maintain an enzyme affinity and reactivity similar to pNP-fucose.

Gli stili APA, Harvard, Vancouver, ISO e altri

4

Ojeda, Kristylea J., Jodie M. Box e K. Dale Noel. "Genetic Basis for Rhizobium etli CE3 O-Antigen O-Methylated Residues That Vary According to Growth Conditions". Journal of Bacteriology 192, n. 3 (30 novembre 2009): 679–90. http://dx.doi.org/10.1128/jb.01154-09.

Testo completo

Abstract (sommario):

ABSTRACT The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer with O methylation being the predominant type of sugar modification. There are two O-methylated residues that occur, on average, once per complete O antigen: a multiply O-methylated terminal fucose and 2-O methylation of a fucose residue within a repeating unit. The amount of the methylated terminal fucose decreases and the amount of 2-O-methylfucose increases when bacteria are grown in the presence of the host plant, Phaseolus vulgaris, or its seed exudates. Insertion mutagenesis was used to identify open reading frames required for the presence of these O-methylated residues. The presence of the methylated terminal fucose required genes wreA, wreB, wreC, wreD, and wreF, whereas 2-O methylation of internal fucoses required the methyltransferase domain of bifunctional gene wreM. Mutants lacking only the methylated terminal fucose, lacking only 2-O methylation, or lacking both the methylated terminal fucose and 2-O methylation exhibited no other lipopolysaccharide structural defects. Thus, neither of these decorations is required for normal O-antigen length, transport, or assembly into the final lipopolysaccharide. This is in contrast to certain enteric bacteria in which the absence of a terminal decoration severely affects O-antigen length and transport. R. etli mutants lacking only the methylated terminal fucose were not altered in symbiosis with host Phaseolus vulgaris, whereas mutants lacking only 2-O-methylfucose exhibited a delay in nodule development during symbiosis. These results support previous conclusions that the methylated terminal fucose is dispensable for symbiosis, whereas 2-O methylation of internal fucoses somehow facilitates early events in symbiosis.

Gli stili APA, Harvard, Vancouver, ISO e altri

5

Nuñez, Samantha, Maria Barra e Daniel Garrido. "Developing a Fluorescent Inducible System for Free Fucose Quantification in Escherichia coli". Biosensors 13, n. 3 (15 marzo 2023): 388. http://dx.doi.org/10.3390/bios13030388.

Testo completo

Abstract (sommario):

L-Fucose is a monosaccharide abundant in mammalian glycoconjugates. In humans, fucose can be found in human milk oligosaccharides (HMOs), mucins, and glycoproteins in the intestinal epithelium. The bacterial consumption of fucose and fucosylated HMOs is critical in the gut microbiome assembly of infants, dominated by Bifidobacterium. Fucose metabolism is important for the production of short-chain fatty acids and is involved in cross-feeding microbial interactions. Methods for assessing fucose concentrations in complex media are lacking. Here we designed and developed a molecular quantification method of free fucose using fluorescent Escherichia coli. For this, low- and high-copy plasmids were evaluated with and without the transcription factor fucR and its respective fucose-inducible promoter controlling the reporter gene sfGFP. E. coli BL21 transformed with a high copy plasmid containing pFuc and fucR displayed a high resolution across increasing fucose concentrations and high fluorescence/OD values after 18 h. The molecular circuit was specific against other monosaccharides and showed a linear response in the 0–45 mM range. Adjusting data to the Hill equation suggested non-cooperative, simple regulation of FucR to its promoter. Finally, the biosensor was tested on different concentrations of free fucose and the supernatant of Bifidobacterium bifidum JCM 1254 supplemented with 2-fucosyl lactose, indicating the applicability of the method in detecting free fucose. In conclusion, a bacterial biosensor of fucose was validated with good sensitivity and precision. A biological method for quantifying fucose could be useful for nutraceutical and microbiological applications, as well as molecular diagnostics.

Gli stili APA, Harvard, Vancouver, ISO e altri

6

Chan, Pan F., Karen M. O'Dwyer, Leslie M. Palmer, Jennifer D. Ambrad, Karen A. Ingraham, Chi So, Michael A. Lonetto et al. "Characterization of a Novel Fucose-Regulated Promoter (PfcsK) Suitable for Gene Essentiality and Antibacterial Mode-of-Action Studies in Streptococcus pneumoniae". Journal of Bacteriology 185, n. 6 (15 marzo 2003): 2051–58. http://dx.doi.org/10.1128/jb.185.6.2051-2058.2003.

Testo completo

Abstract (sommario):

ABSTRACT The promoter of the Streptococcus pneumoniae putative fuculose kinase gene (fcsK), the first gene of a novel fucose utilization operon, is induced by fucose and repressed by glucose or sucrose. When the streptococcal polypeptide deformylase (PDF) gene (def1, encoding PDF) was placed under the control of P fcsK , fucose-dependent growth of the S. pneumoniae (P fcsK ::def1) strain was observed, confirming the essential nature of PDF in this organism. The mode of antibacterial action of actinonin, a known PDF inhibitor, was also confirmed with this strain. The endogenous fuculose kinase promoter is a tightly regulated, titratable promoter which will be useful for target validation and for confirmation of the mode of action of novel antibacterial drugs in S. pneumoniae.

Gli stili APA, Harvard, Vancouver, ISO e altri

7

Robles-Gómez, Laura, Paula Sáez-Espinosa, Eliana Marina López-Viloria, Andrea López-Botella, Jon Aizpurua e María José Gómez-Torres. "Quantification and Topographical Distribution of Terminal and Linked Fucose Residues in Human Spermatozoa by Using Field Emission Scanning Electron Microscopy (FE-SEM)". International Journal of Molecular Sciences 22, n. 21 (4 novembre 2021): 11947. http://dx.doi.org/10.3390/ijms222111947.

Testo completo

Abstract (sommario):

The modification of sperm glycocalyx is an essential process during sperm capacitation. The presence and redistribution of terminal and linked fucose have been described during in vitro capacitation in humans. However, the influence of the capacitation time on the quantification and localization of terminal and linked fucose is still unknown. In this study, the quantitative and qualitative changes in fucosyl residues during different in vitro capacitation times (1 and 4 h), are simultaneously characterized by using Aleuria aurantia (AAA) lectin–gold labelling and high-resolution field emission scanning electron microscopy (FE-SEM) in human sperm. A significant decrease was found in the number of terminal fucose registered in the whole sperm head during the in vitro capacitation. Nevertheless, the quantification of fucose residues after 1 h of in vitro capacitation was very similar to those found after 4 h. Therefore, the changes observed in terminal and linked fucose during capacitation were not time-dependent. Furthermore, the comprehensive analysis of the topographic distribution showed the preferential fucosyl location in the acrosomal region and the presence of distinct clusters distributed over the head in all the studied conditions. Overall, these findings corroborate the validity of FE-SEM combined with gold labelling to register changes in surface molecules during in vitro sperm capacitation.

Gli stili APA, Harvard, Vancouver, ISO e altri

8

Tollefsen, S. E., e J. L. Rosenblum. "Role of terminal fucose residues in clearance of human glycosylated alpha-amylase". American Journal of Physiology-Gastrointestinal and Liver Physiology 255, n. 3 (1 settembre 1988): G374—G381. http://dx.doi.org/10.1152/ajpgi.1988.255.3.g374.

Testo completo

Abstract (sommario):

Human glycosylated alpha-amylase contains a single biantennary N-linked oligosaccharide that terminates with the structure Fuc alpha 1,3(Gal beta 1,4)GlcNAc. To examine the role of terminal fucose in the clearance of alpha-amylase, we used lectin affinity chromatography to isolate an alpha-amylase fraction that contains two terminal fucoses (one in each branch of the oligosaccharide) and a fraction from which both terminal fucoses have been enzymatically removed. In the rat, the rate of clearance of the radioiodinated fraction with terminal fucoses is rapid (t1/2 = 12 min) and is slowed by mannosylated but not galactosylated bovine serum albumin. The rate of clearance of the radioiodinated alpha-amylase fraction with no terminal fucoses is also rapid (t1/2 = 9.5 min), but the clearance is now slowed by galactosylated bovine serum albumin. These findings indicate that the fucosylated and defucosylated alpha-amylase fractions are recognized by different carbohydrate-specific receptors. We conclude therefore that terminal fucose is the recognition marker that effects the physiological clearance of this glycoprotein.

Gli stili APA, Harvard, Vancouver, ISO e altri

9

Kim, In Jung, e Kyoung Heon Kim. "Thermophilic l-fucose isomerase from Thermanaeromonas toyohensis for l-fucose synthesis from l-fuculose". Process Biochemistry 96 (settembre 2020): 131–37. http://dx.doi.org/10.1016/j.procbio.2020.05.017.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

10

Ropartz, David, Lery Marion, Mathieu Fanuel, Jasna Nikolic, Murielle Jam, Robert Larocque, Elizabeth Ficko-Blean, Gurvan Michel e Helene Rogniaux. "In-depth structural characterization of oligosaccharides released by GH107 endofucanase MfFcnA reveals enzyme subsite specificity and sulfated fucan substructural features". Glycobiology 32, n. 4 (4 dicembre 2021): 276–88. http://dx.doi.org/10.1093/glycob/cwab125.

Testo completo

Abstract (sommario):

Abstract The extracellular matrix of brown algae represents an abundant source of fucose-containing sulfated polysaccharides (FCSPs). FCSPs include sulfated fucans, essentially composed of fucose, and highly heterogeneous fucoidans, comprising various monosaccharides. Despite a range of potentially valuable biological activities, the structures of FCSPs are only partially characterized and enzymatic tools leading to their deconstruction are rare. Previously, the enzyme MfFcnA was isolated from the marine bacterium Mariniflexile fucanivorans and biochemically characterized as an endo-α-1 → 4-l-fucanase, the first member of glycoside hydrolase family 107. Here, MfFcnA was used as an enzymatic tool to deconstruct the structure of the sulfated fucans from Pelvetia canaliculata (Fucales brown alga). Oligofucans released by MfFcnA at different time points were characterized using mass spectrometry coupled with liquid chromatography and tandem mass spectrometry through Charge Transfer Dissociation. This approach highlights a large diversity in the structures released. In particular, the analyses show the presence of species with less than three sulfates per two fucose residues. They also reveal species with monosaccharides other than fucose and the occurrence of laterally branched residues. Precisely, the lateral branching is either in the form of a hexose accompanied by a trisulfated fucose nearby, or of a side chain of fucoses with a pentose as the branching point on the polymer. Overall, the results indicate that the structure of sulfated fucans from P. canaliculata is more complex than expected. They also reveal the interesting capacity of MfFcnA to accommodate different substrates, leading to structurally diverse oligofucan products that potentially could be screened for bioactivities.

Gli stili APA, Harvard, Vancouver, ISO e altri

11

Kato, S., e N. Akamatsu. "Alterations in fucosyl oligosaccharides of glycoproteins during rat liver regeneration". Biochemical Journal 229, n. 2 (15 luglio 1985): 521–28. http://dx.doi.org/10.1042/bj2290521.

Testo completo

Abstract (sommario):

[3H]Fucose-labelled glycopeptides in the slices of liver 24h after partial hepatectomy were fractionated on Sephadex G-50. Glycopeptides from regenerating liver contained a higher proportion of lower-Mr components than did controls. Regenerating liver contained a higher proportion of glycopeptides that were bound to concanavalin A-Sepharose and were subsequently eluted with 20mM-methyl alpha-D-glucopyranoside than did controls. Concanavalin A-bound glycopeptides from each source were entirely bound to a lentil lectin-Sepharose column. Both the concanavalin A-bound and -unbound fractions from regenerating liver were indistinguishable from the respective controls by Bio-Gel P6 column chromatography and neuraminidase digestion. These results show that fucosyl glycopeptides from regenerating liver contain a higher proportion of biantennary species with core fucose residues than do controls. Glycopeptides from regenerating livers 12h, 72h and 144h after partial hepatectomy were also examined; however, the difference was not significant. These observations suggest that the alterations in fucosyl glycopeptides may be related to rapid growth of hepatocytes 24h after partial hepatectomy. No significant difference was found in either [3H]mannose- or [3H]fucose-labelled glycoproteins from regenerating liver and from controls by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, suggesting that the alteration in glycopeptides should depend on some differences in the late stage of oligosaccharide processing.

Gli stili APA, Harvard, Vancouver, ISO e altri

12

Kim, Jungyeon, Yu Cheong, Inho Jung e Kyoung Kim. "Metabolomic and Transcriptomic Analyses of Escherichia coli for Efficient Fermentation of L-Fucose". Marine Drugs 17, n. 2 (29 gennaio 2019): 82. http://dx.doi.org/10.3390/md17020082.

Testo completo

Abstract (sommario):

L-Fucose, one of the major monomeric sugars in brown algae, possesses high potential for use in the large-scale production of bio-based products. Although fucose catabolic pathways have been enzymatically evaluated, the effects of fucose as a carbon source on intracellular metabolism in industrial microorganisms such as Escherichia coli are still not identified. To elucidate the effects of fucose on cellular metabolism and to find clues for efficient conversion of fucose into bio-based products, comparative metabolomic and transcriptomic analyses were performed on E. coli on L-fucose and on D-glucose as a control. When fucose was the carbon source for E. coli, integration of the two omics analyses revealed that excess gluconeogenesis and quorum sensing led to severe depletion of ATP, resulting in accumulation and export of fucose extracellularly. Therefore, metabolic engineering and optimization are needed for E. coil to more efficiently ferment fucose. This is the first multi-omics study investigating the effects of fucose on cellular metabolism in E. coli. These omics data and their biological interpretation could be used to assist metabolic engineering of E. coli producing bio-based products using fucose-containing brown macroalgae.

Gli stili APA, Harvard, Vancouver, ISO e altri

13

Autieri, Steven M., Jeremy J. Lins, Mary P. Leatham, David C. Laux, Tyrrell Conway e Paul S. Cohen. "l-Fucose Stimulates Utilization of d-Ribose by Escherichia coli MG1655 ΔfucAO and E. coli Nissle 1917 ΔfucAO Mutants in the Mouse Intestine and in M9 Minimal Medium". Infection and Immunity 75, n. 11 (20 agosto 2007): 5465–75. http://dx.doi.org/10.1128/iai.00822-07.

Testo completo

Abstract (sommario):

ABSTRACT Escherichia coli MG1655 uses several sugars for growth in the mouse intestine. To determine the roles of l-fucose and d-ribose, an E. coli MG1655 ΔfucAO mutant and an E. coli MG1655 ΔrbsK mutant were fed separately to mice along with wild-type E. coli MG1655. The E. coli MG1655 ΔfucAO mutant colonized the intestine at a level 2 orders of magnitude lower than that of the wild type, but the E. coli MG1655 ΔrbsK mutant and the wild type colonized at nearly identical levels. Surprisingly, an E. coli MG1655 ΔfucAO ΔrbsK mutant was eliminated from the intestine by either wild-type E. coli MG1655 or E. coli MG1655 ΔfucAO, suggesting that the ΔfucAO mutant switches to ribose in vivo. Indeed, in vitro growth experiments showed that l-fucose stimulated utilization of d-ribose by the E. coli MG1655 ΔfucAO mutant but not by an E. coli MG1655 ΔfucK mutant. Since the ΔfucK mutant cannot convert l-fuculose to l-fuculose-1-phosphate, whereas the ΔfucAO mutant accumulates l-fuculose-1-phosphate, the data suggest that l-fuculose-1-phosphate stimulates growth on ribose both in the intestine and in vitro. An E. coli Nissle 1917 ΔfucAO mutant, derived from a human probiotic commensal strain, acted in a manner identical to that of E. coli MG1655 ΔfucAO in vivo and in vitro. Furthermore, l-fucose at a concentration too low to support growth stimulated the utilization of ribose by the wild-type E. coli strains in vitro. Collectively, the data suggest that l-fuculose-1-phosphate plays a role in the regulation of ribose usage as a carbon source by E. coli MG1655 and E. coli Nissle 1917 in the mouse intestine.

Gli stili APA, Harvard, Vancouver, ISO e altri

14

Bradley, S. A., C. R. Tinsley, J. A. R. Muiry e P. J. F. Henderson. "Proton-linked l-fucose transport in Escherichia coli". Biochemical Journal 248, n. 2 (1 dicembre 1987): 495–500. http://dx.doi.org/10.1042/bj2480495.

Testo completo

Abstract (sommario):

1. Addition of L-fucose to energy-depleted anaerobic suspensions of Escherichia coli elicited an uncoupler-sensitive alkaline pH change diagnostic of L-fucose/H+ symport activity. 2. L-Galactose or D-arabinose were also substrates, but not inducers, for the L-fucose/H+ symporter. 3. L-Fucose transport into subcellular vesicles was dependent upon respiration, displayed a pH optimum of about 5.5, and was inhibited by protonophores and ionophores. 4. These results showed that L-fucose transport into E. coli was energized by the transmembrane electrochemical gradient of protons. 5. Neither steady state kinetic measurements nor assays of L-fucose binding to periplasmic proteins revealed the existence of a second L-fucose transport system.

Gli stili APA, Harvard, Vancouver, ISO e altri

15

Thai Le, Son, Lenka Malinovska, Michaela Vašková, Erika Mező, Viktor Kelemen, Anikó Borbás, Petr Hodek, Michaela Wimmerová e Magdolna Csávás. "Investigation of the Binding Affinity of a Broad Array of l-Fucosides with Six Fucose-Specific Lectins of Bacterial and Fungal Origin". Molecules 24, n. 12 (18 giugno 2019): 2262. http://dx.doi.org/10.3390/molecules24122262.

Testo completo

Abstract (sommario):

Series of multivalent α-l-fucoside containing glycoclusters and variously decorated l-fucosides were synthesized to find potential inhibitors of fucose-specific lectins and study the structure-binding affinity relationships. Tri- and tetravalent fucoclusters were built using copper-mediated azide-alkyne click chemistry. Series of fucoside monomers and dimers were synthesized using various methods, namely glycosylation, an azide-alkyne click reaction, photoinduced thiol-en addition, and sulfation. The interactions between compounds with six fucolectins of bacterial or fungal origin were tested using a hemagglutination inhibition assay. As a result, a tetravalent, α-l-fucose presenting glycocluster showed to be a ligand that was orders of magnitude better than a simple monosaccharide for tested lectins in most cases, which can nominate it as a universal ligand for studied lectins. This compound was also able to inhibit the adhesion of Pseudomonas aeruginosa cells to human epithelial bronchial cells. A trivalent fucocluster with a protected amine functional group also seems to be a promising candidate for designing glycoconjugates and chimeras.

Gli stili APA, Harvard, Vancouver, ISO e altri

16

Ayukawa, Tomonori, Kenjiroo Matsumoto, Hiroyuki O. Ishikawa, Akira Ishio, Tomoko Yamakawa, Naoki Aoyama, Takuya Suzuki e Kenji Matsuno. "Rescue of Notch signaling in cells incapable of GDP-l-fucose synthesis by gap junction transfer of GDP-l-fucose in Drosophila". Proceedings of the National Academy of Sciences 109, n. 38 (4 settembre 2012): 15318–23. http://dx.doi.org/10.1073/pnas.1202369109.

Testo completo

Abstract (sommario):

Notch (N) is a transmembrane receptor that mediates cell–cell interactions to determine many cell-fate decisions. N contains EGF-like repeats, many of which have an O-fucose glycan modification that regulates N-ligand binding. This modification requires GDP-l-fucose as a donor of fucose. The GDP-l-fucose biosynthetic pathways are well understood, including the de novo pathway, which depends on GDP-mannose 4,6 dehydratase (Gmd) and GDP-4-keto-6-deoxy-d-mannose 3,5-epimerase/4-reductase (Gmer). However, the potential for intercellularly supplied GDP-l-fucose and the molecular basis of such transportation have not been explored in depth. To address these points, we studied the genetic effects of mutating Gmd and Gmer on fucose modifications in Drosophila. We found that these mutants functioned cell-nonautonomously, and that GDP-l-fucose was supplied intercellularly through gap junctions composed of Innexin-2. GDP-l-fucose was not supplied through body fluids from different isolated organs, indicating that the intercellular distribution of GDP-l-fucose is restricted within a given organ. Moreover, the gap junction-mediated supply of GDP-l-fucose was sufficient to support the fucosylation of N-glycans and the O-fucosylation of the N EGF-like repeats. Our results indicate that intercellular delivery is a metabolic pathway for nucleotide sugars in live animals under certain circumstances.

Gli stili APA, Harvard, Vancouver, ISO e altri

17

Andrianopoulos, Kanella, Lei Wang e Peter R. Reeves. "Identification of the Fucose Synthetase Gene in the Colanic Acid Gene Cluster of Escherichia coli K-12". Journal of Bacteriology 180, n. 4 (15 febbraio 1998): 998–1001. http://dx.doi.org/10.1128/jb.180.4.998-1001.1998.

Testo completo

Abstract (sommario):

ABSTRACT GDP–l-fucose, the substrate for fucosyltransferases for addition of fucose to polysaccharides or glycoproteins in both procaryotes and eucaryotes, is made from GDP–d-mannose.l-Fucose is a component of bacterial surface antigens, including the extracellular polysaccharide colanic acid produced by most Escherichia coli strains. We previously sequenced theE. coli colanic acid gene cluster and identified one of the GDP–l-fucose biosynthetic pathway genes, gmd. We report here the identification of the gene (fcl), located downstream of gmd, encoding the fucose synthetase.

Gli stili APA, Harvard, Vancouver, ISO e altri

18

Chow, Wai Ling, e Yuan Kun Lee. "Free fucose is a danger signal to human intestinal epithelial cells". British Journal of Nutrition 99, n. 3 (marzo 2008): 449–54. http://dx.doi.org/10.1017/s0007114507812062.

Testo completo

Abstract (sommario):

Fucose is present in foods, and it is a major component of human mucin glycoproteins and glycolipids.l-Fucose can also be found at the terminal position of many cell-surface oligosaccharide ligands that mediate cell-recognition and adhesion-signalling pathways. Mucin fucose can be released through the hydrolytic activity of pathogens and indigenous bacteria, leading to the release of free fucose into the intestinal lumen. The immunomodulating effects of free fucose on intestinal epithelial cells (enterocyte-like Caco-2) were investigated. It was found that the presence ofl-fucose up regulated genes and secretion of their encoded proteins that are involved in both the innate and adaptive immune responses, possibly via the toll-like receptor-2 signalling pathway. These include TNFSF5, TNFSF7, TNF-α, IL12, IL17 and IL18.Besides modulating immune reactions in differentiated Caco-2 cells, fucose induced a set of cytokine genes that are involved in the development and proliferation of immune cells. These include the bone morphogenetic proteins (BMP) BMP2, BMP4, IL5, thrombopoietin and erythropoietin. In addition, the up regulated gene expression of fibroblast growth factor-2 may help to promote epithelial cell restitution in conjunction with the enhanced expression of transforming growth factor-β mRNA. Since the exogenous fucose was not metabolised by the differentiated Caco-2 cells as a carbon source, the reactions elicited were suggested to be a result of the direct interaction of fucose and differentiated Caco-2 cells. The presence of free fucose may signal the invasion of mucin-hydrolysing microbial cells and breakage of the mucosal barrier. The intestinal epithelial cells respond by up regulation and secretion of cytokines, pre-empting the actual invasion of pathogens.

Gli stili APA, Harvard, Vancouver, ISO e altri

19

Sanz, Sílvia, Giulia Bandini, Diego Ospina, Maria Bernabeu, Karina Mariño, Carmen Fernández-Becerra e Luis Izquierdo. "Biosynthesis of GDP-fucose and Other Sugar Nucleotides in the Blood Stages of Plasmodium falciparum". Journal of Biological Chemistry 288, n. 23 (24 aprile 2013): 16506–17. http://dx.doi.org/10.1074/jbc.m112.439828.

Testo completo

Abstract (sommario):

Carbohydrate structures play important roles in many biological processes, including cell adhesion, cell-cell communication, and host-pathogen interactions. Sugar nucleotides are activated forms of sugars used by the cell as donors for most glycosylation reactions. Using a liquid chromatography-tandem mass spectrometry-based method, we identified and quantified the pools of UDP-glucose, UDP-galactose, UDP-N-acetylglucosamine, GDP-mannose, and GDP-fucose in Plasmodium falciparum intraerythrocytic life stages. We assembled these data with the in silico functional reconstruction of the parasite metabolic pathways obtained from the P. falciparum annotated genome, exposing new active biosynthetic routes crucial for further glycosylation reactions. Fucose is a sugar present in glycoconjugates often associated with recognition and adhesion events. Thus, the GDP-fucose precursor is essential in a wide variety of organisms. P. falciparum presents homologues of GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase enzymes that are active in vitro, indicating that most GDP-fucose is formed by a de novo pathway that involves the bioconversion of GDP-mannose. Homologues for enzymes involved in a fucose salvage pathway are apparently absent in the P. falciparum genome. This is in agreement with in vivo metabolic labeling experiments showing that fucose is not significantly incorporated by the parasite. Fluorescence microscopy of epitope-tagged versions of P. falciparum GDP-mannose 4,6-dehydratase and GDP-l-fucose synthase expressed in transgenic 3D7 parasites shows that these enzymes localize in the cytoplasm of P. falciparum during the intraerythrocytic developmental cycle. Although the function of fucose in the parasite is not known, the presence of GDP-fucose suggests that the metabolite may be used for further fucosylation reactions.

Gli stili APA, Harvard, Vancouver, ISO e altri

20

Appelmelk, B. J., B. Shiberu, C. Trinks, N. Tapsi, P. Y. Zheng, T. Verboom, J. Maaskant et al. "Phase Variation in Helicobacter pylori Lipopolysaccharide". Infection and Immunity 66, n. 1 (1998): 70–76. http://dx.doi.org/10.1128/iai.66.1.70-76.1998.

Testo completo

Abstract (sommario):

Helicobacter pylori NCTC 11637 lipopolysaccharide (LPS) expresses the human blood group antigen Lewis x (Lex) in a polymeric form. Lex is β-d-galactose-(1-4)-[α-l-fucose-(1-3)]-β-d-acetylglucosamine. Schematically the LPS structure is (Lex) n -core-lipid A. In this report, we show that Lex expression is not a stable trait but that LPS displays a high frequency (0.2 to 0.5%) of phase variation, resulting in the presence of several LPS variants in one bacterial cell population. One type of phase variation implied the loss of α1,3-linked fucose, resulting in variants that expressed nonsubstituted polylactosamines (also called the i antigen), i.e., Lex minus fucose; LPS: (lactosamine) n -core-lipid A. The switch of Lex to i antigen was reversible. A second group of variants arose by loss of polymeric main chain which resulted in expression of monomeric Ley; LPS: (Ley)-core-lipid A. A third group of variants arose by acquisition of α1,2-linked fucose which hence expressed Lex plus Ley; LPS: (Ley)(Lex) n -core-lipid A. The second and third group of variants switched back to the parental phenotype [(Lex) n -core-lipid A] in lower frequencies. Part of the variation can be ascribed to altered expression levels of glycosyltransferase levels as assessed by assaying the activities of galactosyl-, fucosyl-, andN-acetylglucosaminyltransferases. Clearly phase variation increases the heterogeneity of H. pylori, and this process may be involved in generating the very closely related yet genetically slightly different strains that have been isolated from one patient.

Gli stili APA, Harvard, Vancouver, ISO e altri

21

Stanková, J., e M. Rola-Pleszczynski. "Fucose-activated killer (FAK) cells: anomalous killers with augmented cytotoxic activity." Journal of Immunology 135, n. 6 (1 dicembre 1985): 3719–28. http://dx.doi.org/10.4049/jimmunol.135.6.3719.

Testo completo

Abstract (sommario):

Abstract The effects of monosaccharides on various lymphocyte functions have provided useful probes for the study of cell-cell interactions. In this report, we show that a monosaccharide, alpha-L-fucose, significantly enhances the cytolytic capacity of MLC-induced or preincubated effector cells. The increase in activity was seen against cytotoxic T lymphocyte (CTL) targets (:relevant PHA blasts), natural killer cell (NK) targets (:K562), and natural cytotoxic cell (NC) targets (:MA-160). In addition, traditionally NK-insensitive targets (Raji cells, irrelevant and autologous PHA blasts) were lysed after preincubation of effector cells with fucose. Conversely, ADCC activity was not significantly increased with fucose induction. The addition of fucose directly to assay cultures did not enhance NK or CTL activity, whereas other sugars, such as alpha-methyl-D-mannoside and D-fructose, were inhibitory. The proportion of target-binding cells was not affected by preincubation with fucose, but the percentage of lytic conjugates was doubled. Significant augmentation of NK activity could be observed within 24 hr of incubation with alpha-L-fucose. Conversely, when fucose was added more than 24 hr after initiation of the culture, the increase in cytolytic activity was not observed. Parallel to the increase in cytolytic activity, after preincubation with alpha-L-fucose, an increase in the expression of a newly defined human NC cell marker, HNC-1A3, was observed. The HNC-1A3+ cells were not the major subpopulation responsible for fucose-induced activity, as ascertained by the use of positively sorted cells. The populations expressing antigens defined by the antibodies OKT8 and Leu-7 showed no quantitative change. The treatment of cells with OKM1 and complement (C) before culture eliminated fucose-enhanced killing, whereas similar treatment with OKT8 and C had no significant effect. The induction of fucose-activated killers (FAK) does not result in higher concentrations of interferon (IFN) in culture supernatants, in contrast to poly I:C, which induced both higher cytolytic activity and high titers of IFN. In addition, the induction of FAK was not sensitive to 100 ng/ml of cyclosporin A, suggesting that IL 2 did not play a major role in fucose activation of killing. These results provide strong evidence that alpha-L-fucose is capable of augmenting nonspecific activity by acting on OKM1+ precursors of cytotoxic cells and influencing a postbinding event.

Gli stili APA, Harvard, Vancouver, ISO e altri

22

Baysal, Bora, Funda Tüzün, Defne Engür, Seda Özbal, BekirUğur Ergür, Burçin İşcan, Ebru Yücesoy, Nuray Duman, Hasan Özkan e Abdullah Kumral. "Prophylactic Fucose can Alleviate Lipopolysaccharide-Induced Cholestatic Liver Injury in Neonatal Rats". Journal of Pediatric Infectious Diseases 14, n. 05 (13 agosto 2019): 253–59. http://dx.doi.org/10.1055/s-0039-1694710.

Testo completo

Abstract (sommario):

Objectives Cholestasis is a common disease of the liver in premature infants and no specific preventive treatment is currently available. Fucose, one of the monosaccharide building blocks of human milk oligosaccharides, may prevent cholestatic hepatic injury by various mechanisms. The aim of this study was to investigate the protective effect of fucose treatment after endotoxin-induced cholestasis in a rat model. Methods Wistar rat pups were divided into four groups as: group I, control group; group II, fucose-supplemented group; group III, lipopolysaccharide (LPS)-administered group, and group IV, LPS-exposed and fucose-supplemented group. Fucose was given 100 mg/kg i.p. every other day between PN5–17. LPS was administered on PN19 to establish endotoxin-induced cholestasis model. On PN21, animals were sacrificed to evaluate liver cell damage and apoptosis. Results Fucose supplementation significantly improved the biochemical parameters that deteriorated in LPS-administered group, significantly increased the expression of bile salt export pump, reduced the number of apoptotic cell death, and greatly prevented LPS-induced cholestatic hepatic injury. Conclusion Given our results, fucose may be useful in reducing hepatic injury and might possess clinical relevance for the preventive treatment of inflammation-induced cholestatic injury in newborns.

Gli stili APA, Harvard, Vancouver, ISO e altri

23

Sakai, T., K. Yamamoto, H. Yokota, K. Hakozaki-Usui, F. Hino e I. Kato. "Rapid, simple enzymatic assay of free L-fucose in serum and urine, and its use as a marker for cancer, cirrhosis, and gastric ulcers". Clinical Chemistry 36, n. 3 (1 marzo 1990): 474–76. http://dx.doi.org/10.1093/clinchem/36.3.474.

Testo completo

Abstract (sommario):

Abstract We devised a kit for use with automated analyzers, for assay of urinary free L-fucose by means of a newly isolated L-fucose dehydrogenase (EC 1.1.1.122), and we measured L-fucose in healthy subjects, cancer patients, and patients with other diseases. It takes 10 min to complete one assay. Absorbance and L-fucose concentration were linearly related up to at least 3.0 mmol/L, analytical recovery was 90-104%, and intra- and interassay coefficients of variation were less than 4.2% and 7.8%, respectively. The concentrations of L-fucose, corrected for creatinine, were significantly higher than those in healthy subjects in nine of 18 patients with gastric ulcers, 19 of 21 patients with cirrhosis of the liver, and 206 of 366 patients with some type of cancer, reflecting a changed L-fucose metabolism. Because urine specimens are analyzed and the test is rapid and inexpensive, this method may be suitable for mass screening for some kinds of cancer, cirrhosis, and gastric ulcers.

Gli stili APA, Harvard, Vancouver, ISO e altri

24

Anokhina, E. P., M. M. Isuva, S. V. Startseva, E. A. Motina, N. A. Mihailova e O. S. Korneeva. "INVESTIGATION OF PREBIOTIC, IMMUNOSTIMULATING PROPERTIES OF FUCOSE AND ITS EFFECT ON REPRODUCTIVE FUNCTION". Journal of microbiology epidemiology immunobiology, n. 6 (28 dicembre 2018): 110–14. http://dx.doi.org/10.36233/0372-9311-2018-6-110-114.

Testo completo

Abstract (sommario):

Aim. Investigation of the effect of fucose in the diet on the gastrointestinal microflora of experimental animals with experimental dysbiosis, the humoral factors of nonspecific immunity, as well as the degree of fucosylation of oocytes and the proportion of oocytes that can be fertilized. Materials and methods. Prebiotic properties of fucose were studied by analyzing the luminal microflora of experimental mice against the background of experimental dysbiosis. Investigation of factors of nonspecific immunity was carried out after immunization of mice according to the level of antibody formation in blood serum by the method of enzyme immunoassay. The degree of fucosylation of oocytes was assessed by the intensity of their luminescence upon microscopy of oocytes of experimental mice on a fluorescent microscope. Results. The use of fucose in all tested doses led to the restoration of the composition and quantity of the gastrointestinal microflora. For the correction of dysbiosis, the optimal concentration of fucose was 0.02% of the body weight of the experimental animals. Inclusion of fucose in a diet of experimental animals in the amount of 0.008% to the body weight provided the highest level of immune response. The degree of fucosylation of oocytes, the proportion of oocytes capable of fertilization was increased when fucose were introduced in the amount of 0.008% to the body weight of the mice. Conclusion. Bifidogenic and lactogenic activity of fucose is established. The ability of fucose to stimulate an increase in the level of antibodies in in blood serum is shown. The tendency of positive effect of fucose in the diet of mice on the degree of fucosylation of oocytes was revealed.

Gli stili APA, Harvard, Vancouver, ISO e altri

25

Higgins, Melanie A., e Alisdair B. Boraston. "Structure of the fucose mutarotase fromStreptococcus pneumoniaein complex withL-fucose". Acta Crystallographica Section F Structural Biology and Crystallization Communications 67, n. 12 (30 novembre 2011): 1524–30. http://dx.doi.org/10.1107/s1744309111046343.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

26

Hao, Huilin, Zilei Liu, Peng Wu e Robert Haltiwanger. "Abstract 1667: Profiling of O-fucose proteome using fucose analog". Journal of Biological Chemistry 299, n. 3 (2023): S392. http://dx.doi.org/10.1016/j.jbc.2023.103744.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

27

Yuan, Xiao, Tomohiko Nakao, Hina Satone, Kazuyuki Ohara, Yuri Kominami, Miho Ito, Teruki Aizawa, Tomoya Ueno e Hideki Ushio. "The Effects of Brown Algae-Derived Monosaccharide L-Fucose on Lipid Metabolism in C57BL/6J Obese Mice". Nutrients 12, n. 12 (11 dicembre 2020): 3798. http://dx.doi.org/10.3390/nu12123798.

Testo completo

Abstract (sommario):

Obesity is a global public health problem and a risk factor for several metabolic disorders as well as cancer. In this study, we investigated the effects of L-fucose on lipid metabolism through chronic and acute in vivo experiments in mice. In the chronic test, mice were fed a high-calorie diet (HCD) containing 0.0001%, 0.001%, 0.01%, and 0.1% L-fucose for one month. The L-fucose supplementation inhibited body weight and visceral fat mass gain in HCD-fed mice. The results of the acute test showed that L-fucose increased the ratio of serum high molecular weight adiponectin and enhanced glucose and lipid catabolism. Furthermore, L-fucose also decreased the expression of adipogenic genes (peroxisome proliferator-activated receptor γ and cluster of differentiation 36). In conclusion, this study provides a new approach to combat obesity and the related diseases.

Gli stili APA, Harvard, Vancouver, ISO e altri

28

Tomsik, Pavel, Tomas Soukup, Eva Cermakova, Stanislav Micuda, Mohamed Niang, Lenka Sucha e Martina Rezacova. "L-rhamnose and L-fucose suppress cancer growth in mice". Open Life Sciences 6, n. 1 (1 febbraio 2011): 1–9. http://dx.doi.org/10.2478/s11535-010-0087-0.

Testo completo

Abstract (sommario):

AbstractIt is documented that deficient fucosylation may play an important role in the pathogenesis of cancer. Since the supplementation of L-fucose could restore fucosylation in both in vitro and in vivo conditions, our intent was to examine the effect of intraperitoneal administration of L-fucose and L-rhamnose (a similar deoxysaccharide) on tumour growth, mitotic activity and metastatic setting of a solid form of Ehrlich carcinoma as well as on the survival rate of tumour bearing mice. Both L-fucose and L-rhamnose exerted a significant suppressive effect on tumour growth (P<0.05). After 10 days of therapy, the greatest inhibition of tumour growth expressed as a percentage of controls was observed in L-rhamnose at a dose of 3 g/kg/day (by 62%) and L-fucose at a dose of 5 g/kg/day (by 47%). Moreover, the mitotic index decreased with increasing doses of L-fucose and L-rhamnose. Prolonged survival of tumour bearing mice was observed after 14 consecutive days of daily administering L-rhamnose. Its optimal dose was estimated to be 3.64 g/kg/day. L-Fucose, however, displayed only a slight effect on the survival of the mice. Our results suggest that L-fucose and especially L-rhamnose have anticancer potential. This study is the first to demonstrate the tumour-inhibitory effect of L-rhamnose.

Gli stili APA, Harvard, Vancouver, ISO e altri

29

Tomek, Markus B., Bettina Janesch, Matthias L. Braun, Manfred Taschner, Rudolf Figl, Clemens Grünwald-Gruber, Michael J. Coyne et al. "A Combination of Structural, Genetic, Phenotypic and Enzymatic Analyses Reveals the Importance of a Predicted Fucosyltransferase to Protein O-Glycosylation in the Bacteroidetes". Biomolecules 11, n. 12 (30 novembre 2021): 1795. http://dx.doi.org/10.3390/biom11121795.

Testo completo

Abstract (sommario):

Diverse members of the Bacteroidetes phylum have general protein O-glycosylation systems that are essential for processes such as host colonization and pathogenesis. Here, we analyzed the function of a putative fucosyltransferase (FucT) family that is widely encoded in Bacteroidetes protein O-glycosylation genetic loci. We studied the FucT orthologs of three Bacteroidetes species—Tannerella forsythia, Bacteroides fragilis, and Pedobacter heparinus. To identify the linkage created by the FucT of B. fragilis, we elucidated the full structure of its nine-sugar O-glycan and found that l-fucose is linked β1,4 to glucose. Of the two fucose residues in the T. forsythia O-glycan, the fucose linked to the reducing-end galactose was shown by mutational analysis to be l-fucose. Despite the transfer of l-fucose to distinct hexose sugars in the B. fragilis and T. forsythia O-glycans, the FucT orthologs from B. fragilis, T. forsythia, and P. heparinus each cross-complement the B. fragilis ΔBF4306 and T. forsythia ΔTanf_01305 FucT mutants. In vitro enzymatic analyses showed relaxed acceptor specificity of the three enzymes, transferring l-fucose to various pNP-α-hexoses. Further, glycan structural analysis together with fucosidase assays indicated that the T. forsythia FucT links l-fucose α1,6 to galactose. Given the biological importance of fucosylated carbohydrates, these FucTs are promising candidates for synthetic glycobiology.

Gli stili APA, Harvard, Vancouver, ISO e altri

30

Hidalgo, Andrés, Songhui Ma, Anna J. Peired, Linnea A. Weiss, Charlotte Cunningham-Rundles e Paul S. Frenette. "Insights into leukocyte adhesion deficiency type 2 from a novel mutation in the GDP-fucose transporter gene". Blood 101, n. 5 (1 marzo 2003): 1705–12. http://dx.doi.org/10.1182/blood-2002-09-2840.

Testo completo

Abstract (sommario):

Leukocyte adhesion deficiency type 2 (LADII) is characterized by defective selectin ligand formation, recurrent infection, and mental retardation. This rare syndrome has only been described in 2 kindreds of Middle Eastern descent who have differentially responded to exogenous fucose treatment. The molecular defect was recently ascribed to single and distinct missense mutations in a putative Golgi guanosine diphosphate (GDP)–fucose transporter. Here, we describe a patient of Brazilian origin with features of LADII. Sequencing of the GDP-fucose transporter revealed a novel single nucleotide deletion producing a shift in the open-reading frame and severe truncation of the polypeptide. Overexpression of the mutant protein in the patient's fibroblasts did not rescue fucosylation, suggesting that the deletion ablated the activity of the transporter. Administration of oral L-fucose to the patient produced molecular and clinical responses, as measured by the appearance of selectin ligands, normalization of neutrophil counts, and prevention of infectious recurrence. The lower neutrophil counts paralleled improved neutrophil interactions with activated endothelium in cremasteric venules of nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice. However, fucose supplementation induced autoimmune neutropenia and the appearance of H antigen on erythrocytes, albeit without evidence of intravascular hemolysis. The robust response to fucose despite a severely truncated transporter suggests alternative means to transport GDP-fucose into the Golgi complex.

Gli stili APA, Harvard, Vancouver, ISO e altri

31

Tai, G. H., G. M. Brown, H. G. Morris, T. N. Huckerby e I. A. Nieduszynski. "Fucose content of keratan sulphates from bovine articular cartilage". Biochemical Journal 273, n. 2 (15 gennaio 1991): 307–10. http://dx.doi.org/10.1042/bj2730307.

Testo completo

Abstract (sommario):

Alkaline-borohydride-reduced keratan sulphate chains were isolated from bovine articular cartilage (6-8-year-old animals). Nine keratan sulphate fractions of increasing molecular weight were prepared by gel-permeation chromatography on a calibrated column of TSK 30 XL. The samples were analysed for fucose and galactose contents (% by wt. of keratan sulphate) and fucose/galactose ratio. The fucose content increased with molecular size, but the galactose content remained constant. It was concluded that the alpha(1→3)-linked fucose [Thornton, Morris, Cockin, Huckerby, Nieduszynski, Carlstedt, Hardingham & Ratcliffe (1989) Biochem. J. 260, 277-282] was located within the poly-N-acetyl-lactosamine repeat sequence of articular-cartilage keratan sulphate.

Gli stili APA, Harvard, Vancouver, ISO e altri

32

Stiller, Regine, e Joachim Thiem. "Enzymatic Synthesis of ß-L-Fucose-1-phosphate and GDP-fucose". Liebigs Annalen der Chemie 1992, n. 5 (19 maggio 1992): 467–71. http://dx.doi.org/10.1002/jlac.199219920183.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

33

Minsaas, J. "On two new derivatives of l-fucose: (Second communication on fucose)". Recueil des Travaux Chimiques des Pays-Bas 51, n. 5 (3 settembre 2010): 475–82. http://dx.doi.org/10.1002/recl.19320510512.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

34

Lee, Jeong, So Oh, Tony Johnston, Seockmo Ku e Geun Ji. "Biocatalysis of Fucodian in Undaria pinnatifida Sporophyll Using Bifidobacterium longum RD47 for Production of Prebiotic Fucosylated Oligosaccharide". Marine Drugs 17, n. 2 (14 febbraio 2019): 117. http://dx.doi.org/10.3390/md17020117.

Testo completo

Abstract (sommario):

Fucosylated oligosaccharide (FO) is known to selectively promote the growth of probiotic bacteria and is currently marketed as a functional health food and prebiotic in infant formula. Despite widespread interest in FO among functional food customers, high production costs due to high raw material costs, especially those related to fucose, are a significant production issue. Therefore, several actions are required before efficient large-scale operations can occur, including (i) identification of inexpensive raw materials from which fucosylated oligosaccharides may be produced and (ii) development of production methods to which functional food consumers will not object (e.g., no genetically modified organisms (GMOs)). Undaria pinnatifida, commonly called Miyeok in Korea, is a common edible brown seaweed plentiful on the shores of the Korean peninsula. In particular, the sporophyll of Undaria pinnatifida contains significant levels of l-fucose in the form of fucoidan (a marine sulfated polysaccharide). If the l-fucose present in Undaria pinnatifida sporophyll was capable of being separated and recovered, l-fucose molecules could be covalently joined to other monosaccharides via glycosidic linkages, making this FO manufacturing technology of value in the functional food market. In our previous work, β-galactosidase (EC 3.2.2.23) from Bifidobacterium longum RD47 (B. longum RD47) was found to have transglycosylation activity and produce FO using purified l-fucose and lactose as substrates (reference). In this research, crude fucodian hydrolysates were separated and recovered from edible seaweed (i.e., U. pinnatifida sporophyll). The extracted l-fucose was purified via gel permeation and ion exchange chromatographies and the recovered l-fucose was used to synthesize FO. B. longum RD47 successfully transglycosilated and produced FO using l-fucose derived from Undaria pinnatifida and lactose as substrates. To the best of our knowledge, this is the first report of synthesized FO using Bifidobacterium spp.

Gli stili APA, Harvard, Vancouver, ISO e altri

35

Saif, Nehal A., Yomna A. Hashem, Heba M. Amin e Ramy K. Aziz. "In Silico and In Vitro Investigation of the Distribution and Expression of Key Genes in the Fucose Operon of Escherichia coli". Microorganisms 11, n. 5 (11 maggio 2023): 1265. http://dx.doi.org/10.3390/microorganisms11051265.

Testo completo

Abstract (sommario):

Many gut bacteria degrade polysaccharides, providing nutritional advantages to their hosts. Fucose, a mucin degradation product, was suggested as a communication molecule between the resident microbiota and external pathogens. However, the precise role and variants of the fucose utilization pathway remain to be elucidated. Here, we computationally and experimentally investigated the fucose utilization operon of E. coli. While the operon is conserved among E. coli genomes, a variant pathway, in which an ABC transporter system replaces the fucose permease gene (fucP), was computationally identified in 50 out of 1058 genomes. Comparative genomics and subsystems analysis results were confirmed by polymerase chain reaction-based screening of 40 human E. coli isolates, which indicated the conservation of fucP in 92.5% of the isolates (vs. 7.5% of its suggested alternative, yjfF). The in silico predictions were confirmed by in vitro experiments comparing the growth of E. coli strains K12, BL21, and isogenic fucose-utilization K12 mutants. Additionally, fucP and fucI transcripts were quantified in E. coli K12 and BL21, after in silico analysis of their expression in 483 public transcriptomes. In conclusion, E. coli utilizes fucose by two pathway variants, with measurable transcriptional differences. Future studies will explore this variation’s impact on signaling and virulence.

Gli stili APA, Harvard, Vancouver, ISO e altri

36

Ke, Jun, Ying Li, Chaoqun Han, Ruohang He, Rong Lin, Wei Qian e Xiaohua Hou. "Fucose Ameliorate Intestinal Inflammation Through Modulating the Crosstalk Between Bile Acids and Gut Microbiota in a Chronic Colitis Murine Model". Inflammatory Bowel Diseases 26, n. 6 (3 febbraio 2020): 863–73. http://dx.doi.org/10.1093/ibd/izaa007.

Testo completo

Abstract (sommario):

Abstract Background Recurrent intestinal inflammation is frequently associated with aberrant bile acid profiles and microbial community. Fucose exerts a protective effect on commensal bacteria in the case of intestinal pathogen infection. We speculated that fucose might also have certain impact on the microbial ecosystem under the chronic colitis setting. Methods To validate our hypothesis, multi-omics examination was performed in combination with microbiomics and metabonomics in a chronic dextran sulfate sodium (DSS) murine model in the presence or absence of fucose. The 16S RNA sequencing was carried out to determine the ileum and colon microbiota. Primary and secondary bile acids, together with the respective taurine and glycine conjugates, were quantified through ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS). Moreover, enzymes involved in regulating bile acid synthesis were also detected. Finally, an experiment was carried out on the antibiotic-treated mice to examine the role of gut microbiota. Results Administration of exogenous-free fucose markedly alleviated the inflammatory response in colitis mice. In addition, excessive intestinal bile acid accumulated in DSS mice was decreased in the presence of fucose, along with the restoration of the compromised regulation on hepatic bile acid synthesis. Moreover, the shifts in bile acid profiles were linked with the improved gut microbiome dysbiosis. However, the protective effects of fucose were abolished in mice treated with antibiotic cocktail, indicating that microbiota played a pivotal role. Conclusions Findings in this study suggest that fucose ameliorates colitis through restoring the crosstalk between bile acid and gut microbiota.

Gli stili APA, Harvard, Vancouver, ISO e altri

37

Marquardt, Thorsten, Kerstin Lühn, Geetha Srikrishna, Hudson H. Freeze, Erik Harms e Dietmar Vestweber. "Correction of Leukocyte Adhesion Deficiency Type II With Oral Fucose". Blood 94, n. 12 (15 dicembre 1999): 3976–85. http://dx.doi.org/10.1182/blood.v94.12.3976.

Testo completo

Abstract (sommario):

Abstract We describe a simple, noninvasive, and effective therapy for leukocyte adhesion deficiency type II (LAD II), a rare inherited disorder of fucose metabolism. This disorder leads to an immunodeficiency caused by the absence of carbohydrate-based selectin ligands on the surface of neutrophils as well as to severe psychomotor and mental retardation. The fucosylation defect in LAD II fibroblasts can be corrected by addition of L-fucose to the culture medium. This prompted us to initiate dietary fucose therapy on a patient with LAD II. Oral supplementation of fucose in this patient induced the expression of fucosylated selectin ligands on neutrophils and core fucosylation of serum glycoproteins. During 9 months of treatment, infections and fever disappeared, elevated neutrophil counts returned to normal, and psychomotor capabilities improved.

Gli stili APA, Harvard, Vancouver, ISO e altri

38

Marquardt, Thorsten, Kerstin Lühn, Geetha Srikrishna, Hudson H. Freeze, Erik Harms e Dietmar Vestweber. "Correction of Leukocyte Adhesion Deficiency Type II With Oral Fucose". Blood 94, n. 12 (15 dicembre 1999): 3976–85. http://dx.doi.org/10.1182/blood.v94.12.3976.424k06_3976_3985.

Testo completo

Abstract (sommario):

We describe a simple, noninvasive, and effective therapy for leukocyte adhesion deficiency type II (LAD II), a rare inherited disorder of fucose metabolism. This disorder leads to an immunodeficiency caused by the absence of carbohydrate-based selectin ligands on the surface of neutrophils as well as to severe psychomotor and mental retardation. The fucosylation defect in LAD II fibroblasts can be corrected by addition of L-fucose to the culture medium. This prompted us to initiate dietary fucose therapy on a patient with LAD II. Oral supplementation of fucose in this patient induced the expression of fucosylated selectin ligands on neutrophils and core fucosylation of serum glycoproteins. During 9 months of treatment, infections and fever disappeared, elevated neutrophil counts returned to normal, and psychomotor capabilities improved.

Gli stili APA, Harvard, Vancouver, ISO e altri

39

Morton, P. A., e S. M. Steiner. "Extracellular and cellular proteins of rat cells with O-glycosidically linked fucose". Biochemical Journal 225, n. 1 (1 gennaio 1985): 59–65. http://dx.doi.org/10.1042/bj2250059.

Testo completo

Abstract (sommario):

Fucose-labelled proteins were examined for the release of low-Mr O-linked fucose substituents after mild alkaline-borohydride treatment. A component tentatively identified as glucosylfucitol (DS) and an apparently higher-Mr component (TS), which also contained fucitol, were observed to be released over a broad molecular-size range of proteins. Approx. 90% of the DS-releasing proteins were in the particulate fraction, whereas only approx. 66% of the TS-releasing proteins were in that fraction. In addition to cell-associated proteins, a substantial proportion of DS-containing proteins were shed into the medium. For example, after 96 h of labelling there was 6-fold more of these components in the growth medium than were cell-associated. Moreover, the incorporation of labelled fucose into both the DS and TS appeared to be cell-population-density-dependent. Despite the apparent wide distribution of these novel fucose substituents in cellular proteins, it seems reasonable to suggest that they have not been routinely observed largely because each represents less than 0.5% of the fucose bound to protein.

Gli stili APA, Harvard, Vancouver, ISO e altri

40

Basak, Prakriti, e Todd L. Lowary. "Synthesis of conjugates of L-fucose and ortho-carborane as potential agents for boron neutron capture therapy". Canadian Journal of Chemistry 80, n. 8 (1 agosto 2002): 943–48. http://dx.doi.org/10.1139/v02-054.

Testo completo

Abstract (sommario):

The synthesis of three potential boron neutron capture therapy agents (68) is reported. The compounds synthesized are comprised of ortho-carborane covalently attached to L-fucose via C-6. Incorporation of the carborane moiety was achieved either through the reaction of an L-fucose-derived alkyne with decaborane or by the coupling of a 6-amino-L-galactopyranose derivative with carborane carboxylic acid chloride (18).Key words: L-fucose, fucosyltransferase, boron neutron capture therapy, ortho-carborane.

Gli stili APA, Harvard, Vancouver, ISO e altri

41

Ruggiero-Lopez, D., M. C. Biol, P. Louisot e A. Martin. "Participation of an endogenous inhibitor of fucosyltransferase activities in the developmental regulation of intestinal fucosylation processes". Biochemical Journal 279, n. 3 (1 novembre 1991): 801–6. http://dx.doi.org/10.1042/bj2790801.

Testo completo

Abstract (sommario):

During the rat weaning period (about day 19 after birth) the intestinal maturation is accompanied by a drastic increase in the fucose content of mucosal glycoconjugates, concomitant with an increase in fucosyltransferase activities. The regulation of this fucosylation process appears to be a rather complex phenomenon, which involves several systems controlling fucosyltransferase activity or substrate availability. An endogenous protein inhibitor of the fucosyltransferase activities displays an opposite developmental pattern to that of fucosyltransferase activities, since its activity is high before weaning and is decreased 5-fold after weaning. Similarly, the GDP-fucose pyrophosphatase activity markedly decreases at weaning. The transformation of GDP-mannose into GDP-fucose increases early, at day 18, preceding the increase in fucosyltransferase activities. Before weaning, and especially at days 14 and 18, high levels of GDP-4-dehydro-6-deoxymannose, the product of the GDP-mannose 4,6-dehydratase activity, are produced during the transformation of GDP-mannose into GDP-fucose, even in excess of reduced coenzyme. This fact indicates that the second step of the transformation (epimerase-reductase reaction) could be a limiting factor for GDP-fucose availability before weaning, but not after weaning. The inverse relationship between the mucosal fucose content (or the fucosyltransferase activity) and the endogenous protein inhibitor during normal postnatal development supports the hypothesis of a physiological role for this inhibitor.

Gli stili APA, Harvard, Vancouver, ISO e altri

42

Mohammed, Alaa, Nidal Mahdi e Fakhri Ahmed. "Biochemical Estimation of Total Sialic Acid, Lipid-Bound Sialic Acid and Fucose in Serum Patients with Nasal and Paranasal Sinus Malignancies". Iraqi Journal of Medical Sciences 19, n. 2 (31 dicembre 2021): 137–46. http://dx.doi.org/10.22578/ijms.19.2.2.

Testo completo

Abstract (sommario):

Background: It is known that measurement of serum total sialic acid (TSA), lipid bound sialic acid (LBSA) and L-Fucose levels may be altered and associated with different types of disease included malignant tumors, therefore, the evaluation of these compounds in serum cancer patients may elucidate the possibility of using this as a diagnostic marker. Objective: To explore the clinical application of TSA, LBSA and L-Fucose serum levels in patients with different site of nasal and para nasal sinus malignancies and compare with a group of healthy controls. Methods: Blood samples obtained from 16 patients with nasal-paranasal sinus malignancies confirmed cases (12 males, 4 females) (age range 45-73 years) and 28 healthy individuals (18 males, 10 females) (age range 38-67 years) participated in this study. Serum TSA and LBSA levels were determined by using colorimetric methods and the serum Fucose level estimation was done based on the method as adopted by Winzler using cysteine reagent. Results: Results showed that serum levels of TSA, LBSA and L-Fucose were significantly higher in cancer patients compared to normal healthy control (P<0.001) and more increased in patients with ethmoid and frontal sinuses cancer group. Conclusion: Estimation of TSA, LBSA and L-Fucose is suggestive to be a reliable marker as well as can use an effective diagnostic biomarker of cancer patients. Keywords: Sialic acid, lipid-bound sialic acid, Fucose, nasal, paranasal sinus cancer, spectrophotometer Citation: Mohammed AK, Mahdi NR, Ahmed FS. Biochemical estimation of total sialic acid, lipid-bound sialic acid and fucose in serum patients with nasal and paranasal sinus malignancies. Iraqi JMS. 2021; 19(2): 137-146. doi: 10.22578/IJMS.19.2.2

Gli stili APA, Harvard, Vancouver, ISO e altri

43

Kim, In Jung, e Kyoung Heon Kim. "l-Fucose Synthesis Using a Halo- and Thermophilic l-Fucose Isomerase from Polyextremophilic Halothermothrix orenii". Applied Sciences 12, n. 8 (15 aprile 2022): 4029. http://dx.doi.org/10.3390/app12084029.

Testo completo

Abstract (sommario):

l-Fucose isomerase (l-FucI)-mediated isomerization is a promising biotechnological approach for synthesizing various rare sugars of industrial significance, including l-fucose. Extremozymes that can retain their functional conformation under extreme conditions, such as high temperature and salinity, offer favorable applications in bioprocesses that accompany harsh conditions. To date, only one thermophilic l-FucI has been characterized for l-fucose synthesis. Here, we report l-FucI from Halothermothrix orenii (HoFucI) which exhibits both halophilic and thermophilic properties. When evaluated under various biochemical conditions, HoFucI exhibited optimal activities at 50–60 °C and pH 7 with 0.5–1 M NaCl in the presence of 1 mM Mn2+ as a cofactor. The results obtained here show a unique feature of HoFucI as a polyextremozyme, which facilitates the biotechnological production of l-fucose using this enzyme.

Gli stili APA, Harvard, Vancouver, ISO e altri

44

Cai, Chao, Lihao Wang, Fei Fan, Haotian Wu, Lei Gao, Ping Zhang, Tiantian Sun, Chendong Yang e Guangli Yu. "Effect of Anomeric Configuration on Stereocontrolled α-Glycosylation of l-Fucose". Synlett 29, n. 20 (23 novembre 2018): 2701–6. http://dx.doi.org/10.1055/s-0037-1611311.

Testo completo

Abstract (sommario):

In this letter, we report an approach to the stereoselective α-glycosylation of l-fucose that is exemplified by effect of anomeric configuration. The neighboring group participation is not compatible with α-glycosylation of l-fucose, therefore the remote participation by 4-O-Bz was employed to control the formation of 1,2-cis-glycosidic bond. Furthermore, we found the anomeric configuration of fucose donor is crucial to stereoselectivity of the glycosylated products. The α/β-mixed products were generated by using β-anomeric donor while the glycosyl donor in α configuration yielded products in high α-selectivity possibly due to the distinct pathway to forming the key intermediates. This phenomenon supplies the basis for the synthesis of complicated natural carbohydrates containing fucose α-glycoside, such as fucoidans, fucosylated N-glycans, and fucosylated chondroitin sulfates, etc.

Gli stili APA, Harvard, Vancouver, ISO e altri

45

Mochimaru, Mari, Hajime Masukawa, Takashi Maoka, Hatem E. Mohamed, Wim F. J. Vermaas e Shinichi Takaichi. "Substrate Specificities and Availability of Fucosyltransferase and β-Carotene Hydroxylase for Myxol 2′-Fucoside Synthesis in Anabaena sp. Strain PCC 7120 Compared with Synechocystis sp. Strain PCC 6803". Journal of Bacteriology 190, n. 20 (15 agosto 2008): 6726–33. http://dx.doi.org/10.1128/jb.01881-07.

Testo completo

Abstract (sommario):

ABSTRACT To elucidate the biosynthetic pathways of carotenoids, especially myxol 2′-glycosides, in cyanobacteria, Anabaena sp. strain PCC 7120 (also known as Nostoc sp. strain PCC 7120) and Synechocystis sp. strain PCC 6803 deletion mutants lacking selected proposed carotenoid biosynthesis enzymes and GDP-fucose synthase (WcaG), which is required for myxol 2′-fucoside production, were analyzed. The carotenoids in these mutants were identified using high-performance liquid chromatography, field desorption mass spectrometry, and 1H nuclear magnetic resonance. The wcaG (all4826) deletion mutant of Anabaena sp. strain PCC 7120 produced myxol 2′-rhamnoside and 4-ketomyxol 2′-rhamnoside as polar carotenoids instead of the myxol 2′-fucoside and 4-ketomyxol 2′-fucoside produced by the wild type. Deletion of the corresponding gene in Synechocystis sp. strain PCC 6803 (sll1213; 79% amino acid sequence identity with the Anabaena sp. strain PCC 7120 gene product) produced free myxol instead of the myxol 2′-dimethyl-fucoside produced by the wild type. Free myxol might correspond to the unknown component observed previously in the same mutant (H. E. Mohamed, A. M. L. van de Meene, R. W. Roberson, and W. F. J. Vermaas, J. Bacteriol. 187:6883-6892, 2005). These results indicate that in Anabaena sp. strain PCC 7120, but not in Synechocystis sp. strain PCC 6803, rhamnose can be substituted for fucose in myxol glycoside. The β-carotene hydroxylase orthologue (CrtR, Alr4009) of Anabaena sp. strain PCC 7120 catalyzed the transformation of deoxymyxol and deoxymyxol 2′-fucoside to myxol and myxol 2′-fucoside, respectively, but not the β-carotene-to-zeaxanthin reaction, whereas CrtR from Synechocystis sp. strain PCC 6803 catalyzed both reactions. Thus, the substrate specificities or substrate availabilities of both fucosyltransferase and CrtR were different in these species. The biosynthetic pathways of carotenoids in Anabaena sp. strain PCC 7120 are discussed.

Gli stili APA, Harvard, Vancouver, ISO e altri

46

Pastuszak, Irena, Catherine Ketchum, Gary Hermanson, Eric J. Sjoberg, Richard Drake e Alan D. Elbein. "GDP-l-fucose Pyrophosphorylase". Journal of Biological Chemistry 273, n. 46 (13 novembre 1998): 30165–74. http://dx.doi.org/10.1074/jbc.273.46.30165.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

47

Thomas, Celestine J., e Avadhesha Surolia. "Mode of Molecular Recognition of l-Fucose by Fucose-Binding Legume Lectins". Biochemical and Biophysical Research Communications 268, n. 2 (febbraio 2000): 262–67. http://dx.doi.org/10.1006/bbrc.2000.2110.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

48

Thomas, Celestine J., e Avadhesha Surolia. "Mode of Molecular Recognition of l-Fucose by Fucose-Binding Legume Lectins". Biochemical and Biophysical Research Communications 270, n. 1 (aprile 2000): 329. http://dx.doi.org/10.1006/bbrc.2000.2426.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

49

Litvinova, Ekaterina A., Victoria D. Bets, Natalya A. Feofanova, Olga V. Gvozdeva, Kseniya M. Achasova, Elizaveta L. Alperina e Elena N. Kozhevnikova. "Dietary Fucose Affects Macrophage Polarization and Reproductive Performance in Mice". Nutrients 13, n. 3 (5 marzo 2021): 855. http://dx.doi.org/10.3390/nu13030855.

Testo completo

Abstract (sommario):

Intestinal mucus protects epithelial and immune cells from the gut resident microorganisms, and provides growth-promoting factors as mucus-derived O-glycans for beneficial bacteria. A lack of intestinal protective mucus results in changes in the commensal microflora composition, mucosal immune system reprogramming, and inflammation. Previous work has shown that fucose, the terminal glycan chain component of the intestinal glycoprotein Mucin2, and fucoidan polysaccharides have an anti-inflammatory effect in some mouse models of colitis. This study evaluates the effect of fucose on reproductive performance in heterozygous mutant Muc2 female mice. We found that even though Muc2+/− females are physiologically indistinguishable from C57Bl/6 mice, they have a significantly reduced reproductive performance upon dietary fucose supplementation. Metagenomic analysis reveals that the otherwise healthy wild-type siblings of Muc2−/− animals have reduced numbers of some of the intestinal commensal bacterial species, compared to C57BL/6 mice. We propose that the changes in beneficial microflora affect the immune status in Muc2+/− mice, which causes implantation impairment. In accordance with this hypothesis, we find that macrophage polarization during pregnancy is impaired in Muc2+/− females upon addition of fucose. Metabolic profiling of peritoneal macrophages from Muc2+/− females reveals their predisposition towards anaerobic glycolysis in favor of oxidative phosphorylation, compared to C57BL/6-derived cells. In vitro experiments on phagocytosis activity and mitochondrial respiration suggest that fucose affects oxidative phosphorylation in a genotype-specific manner, which might interfere with implantation depending on the initial status of macrophages. This hypothesis is further confirmed in BALB/c female mice, where fucose caused pregnancy loss and opposed implantation-associated M2 macrophage polarization. Taken together, these data suggest that intestinal microflora affects host immunity and pregnancy outcome. At the same time, dietary fucose might act as a differential regulator of macrophage polarization during implantation, depending on the immune status of the host.

Gli stili APA, Harvard, Vancouver, ISO e altri

50

Kamble, Ashok S., Raj Kanthawar e N. Vijayan. "Study of serum fucose level in breast malignancy". International Surgery Journal 6, n. 10 (26 settembre 2019): 3749. http://dx.doi.org/10.18203/2349-2902.isj20194436.

Testo completo

Abstract (sommario):

Background: Although for advanced tumour of breast have certain obvious physical characteristics, seldom is such physical finding seen in early malignant breast tumour. Keeping all these in mind, the present study aims at estimation of serum fucose which may help in early detection of breast malignancy.Methods: The present study was carried out over a period of one and a half year. A total of 68 patients were studied. Out of these 68 cases, 32 cases were having breast malignancy. After noting details history, through examination was done according to the proforma. Investigations were carried out as shown in proforma. Estimation of serum fucose was done in all these cases. Estimation of serum fucose was also done pre-operatively and in post-operative period.Results: It is evident from this that 70% of malignant lumps were seen in upper and outer quadrant of breast, 25% lumps in lower quadrant. It is obvious that as age advances average serum fucose level in breast cancer, starts decreasing. Thus younger patients have high Serum level as compared to old patients. Rise in serum level with the progression of stage of breast cancer. There was significant reduction observed in serum fucose level after surgery (p<0.0001).Conclusions:The estimation of serum fucose level can be used to screen cases of breast malignancy though neither as a strong arbiter, nor as a distinct diagnostic test. Its use is only as an ancillary investigation which may provide collaborative evidence only.

Gli stili APA, Harvard, Vancouver, ISO e altri

Articoli di riviste sul tema "Fucose"

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili