Relevant bibliographies by topics / Oligosaccharide Synthesi

Academic literature on the topic 'Oligosaccharide Synthesi'

Author: Grafiati
Published: 9 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Contents

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Oligosaccharide Synthesi.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Oligosaccharide Synthesi"

1

Fan, Jing, Jiayi Chen, Haochen Wu, Xin Lu, Xibi Fang, Fuquan Yin, Zhihui Zhao, Ping Jiang, and Haibin Yu. "Chitosan Oligosaccharide Inhibits the Synthesis of Milk Fat in Bovine Mammary Epithelial Cells through AMPK-Mediated Downstream Signaling Pathway." Animals 12, no. 13 (June 30, 2022): 1692. http://dx.doi.org/10.3390/ani12131692.

Full text
Abstract:
Chitosan oligosaccharide (COS) is a variety of oligosaccharides, and it is also the only abundant basic amino oligosaccharide in natural polysaccharides. Chitosan oligosaccharide is a low molecular weight product of chitosan after enzymatic degradation. It has many biological effects, such as lipid-lowering, antioxidant and immune regulation. Previous studies have shown that chitosan oligosaccharide has a certain effect on fat synthesis, but the effect of chitosan oligosaccharide on milk fat synthesis of bovine mammary epithelial cells (BMECs) has not been studied. Therefore, this study aimed to investigate chitosan oligosaccharide’s effect on milk fat synthesis in bovine mammary epithelial cells and explore the underlying mechanism. We treated bovine mammary epithelial cells with different concentrations of chitosan oligosaccharide (0, 100, 150, 200, 400 and 800 μg/mL) for 24 h, 36 h and 48 h respectively. To assess the effect of chitosan oligosaccharide on bovine mammary epithelial cells and determine the concentration and time for chitosan oligosaccharide treatment on cells, several in vitro cellular experiments, including on cell viability, cycle and proliferation were carried out. The results highlighted that chitosan oligosaccharide (100, 150 μg/mL) significantly promoted cell viability, cycle and proliferation, increased intracellular cholesterol content, and reduced intracellular triglyceride and non-esterified fatty acids content. Under the stimulation of chitosan oligosaccharide, the expression of genes downstream of Phosphorylated AMP-activated protein kinase (P-AMPK) and AMP-activated protein kinase (AMPK) signaling pathway changed, increasing the expression of peroxisome proliferator-activated receptor alpha (PPARα) and hormone-sensitive lipase (HSL), but the expression of sterol regulatory element-binding protein 1c (SREBP1) and its downstream target gene stearoyl-CoA desaturase (SCD1) decreased. In conclusion, these results suggest that chitosan oligosaccharide may inhibit milk fat synthesis in bovine mammary epithelial cells by activating the AMP-activated protein kinase signaling pathway, promoting the oxidative decomposition of fatty acids and inhibiting fatty acid synthesis.
APA, Harvard, Vancouver, ISO, and other styles
2

Gong, Mengge, Tiechuan Li, Lina Wu, Zhenxing Zhang, Lishi Ren, Xuexin Duan, Hongzhi Cao, Meishan Pei, Jian-Jun Li, and Yuguang Du. "Liquid-Phase and Ultrahigh-Frequency-Acoustofluidics-Based Solid-Phase Synthesis of Biotin-Tagged 6′/3′-Sialyl-N-Acetylglucosamine by Sequential One-Pot Multienzyme System." Catalysts 10, no. 11 (November 19, 2020): 1347. http://dx.doi.org/10.3390/catal10111347.

Full text
Abstract:
6′/3′-Sialylated N-acetyllactosamine (6′/3′-SLN) is important for discrimination of the source (human or avian) of influenza virus strains. Biotinylated oligosaccharides have been widely used for analysis and quick detection. The development of efficient strategies to synthesize biotin-tagged 6′/3′-SLN have become necessary. Effective mixing is essential for enzymatic solid-phase oligosaccharide synthesis (SPOS). In the current study, newly developed technology ultrahigh-frequency-acoustofluidics (UHFA), which can provide a powerful source for efficient microfluidic mixing, solid-phase oligosaccharide synthesis and one-pot multienzyme (OPME) system, were used to develop a new strategy for oligosaccharide synthesis. Firstly, biotinylated N-acetylglucosamine was designed and chemically synthesized through traditional approaches. Secondly, biotinylated 6′- and 3′-sialyl-N-acetylglucosamines were prepared in solution through two sequential OPME modules in with a yield of ~95%. Thirdly, 6′-SLN was also prepared through UHFA-based enzymatic solid-phase synthesis on magnetic beads with a yield of 64.4%. The current strategy would be potentially used for synthesis of functional oligosaccharides.
APA, Harvard, Vancouver, ISO, and other styles
3

Whitfield, Dennis M., Henrianna Pang, Jeremy P. Carver, and Jiri J. Krepinsky. "Syntheses of model oligosaccharides of biological significance. X.•Syntheses and NMR and mass spectral analysis of trideuteriomethyl di-3,6-O-(4-O-β-D-galactopyranosyl-2-acetamido-2-deoxy-β-D-glucopyranosyl)-β-D-galactopyranoside: the I antigen branchpoint penta- and tetrasaccharides and a related trisaccharide." Canadian Journal of Chemistry 68, no. 6 (June 1, 1990): 942–52. http://dx.doi.org/10.1139/v90-147.

Full text
Abstract:
As part of our studies of complex oligosaccharides, in particular their three-dimensional structure, we have synthesized the antigen I branchpoint penta- and tetrasaccharides. The unbranched trisaccharide 3D was also synthesized, and its derivative 3B served as the intermediate for the synthesis of higher oligosaccharides. NMR spectra of major intermediates as well as of the final oligosaccharides were completely assigned. Mass spectra of the synthetic intermediates and the final oligosaccharides were analyzed and compared with those of a similar group of oligosaccharides containing L-fucose, N-acetyl-D-glucosamine, and D-galactose. Certain observations were made that could be utilized in the interpretation of mass spectra for the structural determination of protected oligosaccharides during the synthesis. Keywords: oligosaccharide synthesis, I antigen, carbohydrate mass spectrometry, carbohydrate NMR spectrometry, Gal-GlcNAc oligomers.
APA, Harvard, Vancouver, ISO, and other styles
4

Villers, C., R. Cacan, A. M. Mir, O. Labiau, and A. Verbert. "Release of oligomannoside-type glycans as a marker of the degradation of newly synthesized glycoproteins." Biochemical Journal 298, no. 1 (February 15, 1994): 135–42. http://dx.doi.org/10.1042/bj2980135.

Full text
Abstract:
The N-glycosylation of proteins is accompanied by the release of soluble oligosaccharide material. Besides oligosaccharide phosphates originating from the cleavage of lipid intermediates, neutral free oligosaccharides represent the major part of this material and are heterogeneous depending on whether the reducing end has one or two N-acetylglucosamine residues. The present study focuses on the intracellular origin of neutral free oligosaccharides in a CHO cell line. Kinetic and pulse-chase experiments clearly indicate that oligosaccharides possessing a chitobiosyl unit are derived from oligosaccharide pyrophosphodolichol, whereas oligosaccharides possessing one N-acetyl-glucosamine residue are derived from newly synthesized glycoprotein. This relationship is confirmed by comparing the glycosylation pattern of lipid donors and glycoproteins with those of neutral free oligosaccharides under various incubation conditions (inhibition of protein synthesis, presence of processing inhibitors, presence or absence of glucose). Degradation of newly synthesized glycoprotein and formation of neutral oligosaccharides with one N-acetylglucosamine residue are inhibited at 16 degrees C but not affected by lysosomotropic agents such as leupeptin or NH4Cl. Together with the fact that the degradation of newly synthesized glycoproteins and the subsequent release of the glycan are recovered in permeabilized cells, these results suggest that this phenomenon occurs in the rough endoplasmic reticulum or in a closely related compartment.
APA, Harvard, Vancouver, ISO, and other styles
5

DENYER, Kay, Darren WAITE, Anne EDWARDS, Cathie MARTIN, and Alison M. SMITH. "Interaction with amylopectin influences the ability of granule-bound starch synthase I to elongate malto-oligosaccharides." Biochemical Journal 342, no. 3 (September 5, 1999): 647–53. http://dx.doi.org/10.1042/bj3420647.

Full text
Abstract:
This paper examines the properties in soluble form of two isoforms of starch synthase. One of these, granule-bound starch synthase I (GBSSI), is responsible for the synthesis of amylose inside the amylopectin matrix of the starch granule in vivo. The other, starch synthase II (SSII), is involved in amylopectin synthesis. Both isoforms can use amylopectin and malto-oligosaccharide as substrates in vitro. As well as acting as a substrate for GBSSI, amylopectin acts as an effector of this isoform, increasing the rate at which it elongates malto-oligosaccharides and promoting a processive rather than distributive mode of elongation of these compounds. The affinity of GBSSI for amylopectin as an effector is greater than its affinity for amylopectin as a substrate. The rate and mode of elongation of malto-oligosaccharides by SSII are not influenced by amylopectin. These results suggest that specific interaction with amylopectin in the matrix of the starch granule is a unique property of GBSSI and is critical in determining the nature of its products.
APA, Harvard, Vancouver, ISO, and other styles
6

Rabiu, Bodun A., Andrew J. Jay, Glenn R. Gibson, and Robert A. Rastall. "Synthesis and Fermentation Properties of Novel Galacto-Oligosaccharides by β-Galactosidases fromBifidobacterium Species." Applied and Environmental Microbiology 67, no. 6 (June 1, 2001): 2526–30. http://dx.doi.org/10.1128/aem.67.6.2526-2530.2001.

Full text
Abstract:
ABSTRACT β-Galactosidase enzymes were extracted from pure cultures ofBifidobacterium angulatum, B. bifidum BB-12, B. adolescentis ANB-7, B. infantis DSM-20088, andB. pseudolongum DSM-20099 and used in glycosyl transfer reactions to synthesize oligosaccharides from lactose. At a lactose concentration of 30% (wt/wt) oligosaccharide yields of 24.7 to 47.6% occurred within 7 h. Examination of the products by thin-layer chromatography and methylation analysis revealed distinct product derived spectra from each enzyme. These were found to be different to that of Oligomate 55, a commercial prebiotic galacto-oligosaccharide. Fermentation testing of the oligosaccharides showed an increase in growth rate, compared to Oligomate 55, with products derived fromB. angulatum, B. bifidum, B. infantis, and B. pseudolongum. However B. adolescentis had a lower growth rates on its oligosaccharide compared with Oligomate 55. Mixed culture testing of the B. bifidum BS-4 oligosaccharide showed that the overall prebiotic effect was equivalent to that of Oligomate 55.
APA, Harvard, Vancouver, ISO, and other styles
7

Hamada, Hiroki, Hatsuyuki Hamada, Kohji Ishihara, Atsuhito Kuboki, Takafumi Iwaki, and Yuya Kiriake. "Enzymatic Synthesis of α-Tocopherol Derivative Glycoside, Daidzein Glycoside, Daidzein Oligosaccharide, Resveratrol Oligosaccharide, and Curcumin Oligosaccharides and Their Anti-Allergic Activity and Neuroprotective Activity." Natural Product Communications 16, no. 10 (October 2021): 1934578X2110290. http://dx.doi.org/10.1177/1934578x211029095.

Full text
Abstract:
Enzymatic glycosylations of an α-tocopherol derivative, daidzein, resveratrol, and curcumin were investigated. The plant polyphenol, resveratrol, was incubated with glucosyltransferase from Phytolacca americana. The resveratrol glycoside obtained was then incubated with cyclodextrin glucanotransferase to obtain resveratrol oligosaccharide. Daidzein and curcumin were also converted into daidzein glycoside, daidzein oligosaccharide, and curcumin oligosaccharides. Also, α-tocopherol derivative, that is, 2, 5,7,8-tetramethyl-2-(4,8-dimethylnonyl)chroman-6-ol, was glycosylated. The glycosides and oligosaccharides had strong anti-allergic activity such as suppression of IgE formation, inhibition of histamine release, and inhibition of O2 - generation. In addition, the glycosides and oligosaccharides showed efficient neuroprotective activity by inhibition of phosphodiesterase.
APA, Harvard, Vancouver, ISO, and other styles
8

Bahar, Bojlul, John V. O'Doherty, and Torres Sweeney. "A potential role of IL-6 in the chito-oligosaccharide-mediated inhibition of adipogenesis." British Journal of Nutrition 106, no. 8 (May 18, 2011): 1142–53. http://dx.doi.org/10.1017/s0007114511001486.

Full text
Abstract:
Recent studies have suggested that chito-oligosaccharides can have anti-adipogenic properties. The objectives of the present study were to evaluate the anti-adipogenic potential of four different chito-oligosaccharides (molecular weight (MW) < 1000, 1000–3000, 3000–5000 and 5000–10 000 Da) and to identify molecular mechanisms underlying the chito-oligosaccharide-mediated inhibition of adipogenesis. Mouse 3T3-L1 cells were allowed to differentiate in the presence of chito-oligosaccharide. At day 8 post-induction of differentiation, lipid accumulation, free glycerol release and the quantitative expression of adipogenic marker genes were evaluated. Chito-oligosaccharides had concentration- and MW-dependent inhibitory effects on lipid accumulation (P < 0·001 and < 0·05, respectively), as well as a concentration-dependent effect (P < 0·001) on free glycerol release and the expression of adipogenic marker genes. The 5000–10 000 Da chito-oligosaccharide was selected for subsequent molecular studies. A panel of forty-four lipid metabolic pathway-specific genes was analysed by quantitative real-time PCR. Chito-oligosaccharide-mediated inhibition of adipogenesis was associated with the up-regulation of theIL-6gene at all concentrations of chito-oligosaccharide examined and the PG-endoperoxide synthase 2 (PTGS2) gene at higher concentrations of chito-oligosaccharide. The effect of chito-oligosaccharide on gene expression was validated by measuring IL-6 protein concentrations in the media. Finally, anIL-6promoter assay was developed to characterise the effect of chito-oligosaccharide on the transcriptional activity of theIL-6promoter, which was increased in a concentration-dependent manner (P < 0·001). We conclude that IL-6 is a candidate signalling molecule in the chito-oligosaccharide-mediated inhibition of adipogenesis in 3T3-L1 cells.
APA, Harvard, Vancouver, ISO, and other styles
9

Hada, Noriyasu, Tokio Morita, Takashi Ueda, Kazuki Masuda, Hiromi Nakane, Mami Ogane, Kimiaki Yamano, Frank Schweizer, and Fumiyuki Kiuchi. "Synthesis of the Carbohydrate Moiety of Glycoproteins from the Parasite Echinococcus granulosus and Their Antigenicity against Human Sera." Molecules 26, no. 18 (September 17, 2021): 5652. http://dx.doi.org/10.3390/molecules26185652.

Full text
Abstract:
Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the carbohydrate moiety of glycoprotein from Echinococcus granulosus have been accomplished. Trisaccharide Galβ1-3Galβ1-3GalNAcα1-R (A), tetrasaccharide Galα1-4Galβ1-3Galβ1-3GalNAcα1-R (B), and pentasaccharide Galα1-4Galβ1-3Galβ1-3Galβ1-3GalNAcα1-R (C), (R = biotinylated probe) were synthesized by stepwise condensation and/or block synthesis by the use of 5-(methoxycarbonyl)pentyl 2-azido-4,6-O-benzylidene-2-deoxy-α-d-galactopyranoside as a common glycosyl acceptor. The synthesis of the tetrasaccharide and the pentasaccharide was improved from the viewpoint of reducing the number of synthetic steps and increasing the total yield by changing from stepwise condensation to block synthesis. Moreover, hexasaccharide E, which contains the oligosaccharide sequence which occurs in E. granulosus, was synthesized from trisaccharide D. We examined the antigenicity of these five oligosaccharides by an enzyme-linked immunosorbent assay (ELISA). Although compounds of C–E did not exhibit antigenicity against cystic echinococcosis (CE) patient sera, compounds B, D, and E showed good serodiagnostic potential for alveolar echinococcosis (AE).
APA, Harvard, Vancouver, ISO, and other styles
10

Yu, Dawei, Jiayao Feng, Huimin You, Shipeng Zhou, Yan Bai, Jincan He, Hua Cao, Qishi Che, Jiao Guo, and Zhengquan Su. "The Microstructure, Antibacterial and Antitumor Activities of Chitosan Oligosaccharides and Derivatives." Marine Drugs 20, no. 1 (January 13, 2022): 69. http://dx.doi.org/10.3390/md20010069.

Full text
Abstract:
Chitosan obtained from abundant marine resources has been proven to have a variety of biological activities. However, due to its poor water solubility, chitosan application is limited, and the degradation products of chitosan oligosaccharides are better than chitosan regarding performance. Chitosan oligosaccharides have two kinds of active groups, amino and hydroxyl groups, which can form a variety of derivatives, and the properties of these derivatives can be further improved. In this review, the key structures of chitosan oligosaccharides and recent studies on chitosan oligosaccharide derivatives, including their synthesis methods, are described. Finally, the antimicrobial and antitumor applications of chitosan oligosaccharides and their derivatives are discussed.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Oligosaccharide Synthesi"

1

SINGH, MEENAKSHI. "Synthesis of Group B Streptococcus tipe II (GBSII) Oligosaccharide of Vaccine Development." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/680023.

Full text
Abstract:
Carbohydrates are among the most abundant molecules found on the cell surfaces of bacteria, parasites, and viruses. Apart from the conventional roles of carbohydrates as energy sources and structural polymers, carbohydrates are also associated with cancer metastasis, protein stabilization, pathogen infection and the immune response. Cells of our body have sensors made out of carbohydrates on outer surface of plasma membrane and acts as sensors and can detect many kinds of stimuli, and can signal the immune system to respond. Carbohydrate-protein molecular recognition processes have pivotal roles in infections and in immune response to pathogens. To date, several vaccines based on isolated capsular polysaccharides (CPSs) are marketed against infectious diseases. However, the use of isolated capsular polysaccharide poses several limitations, as natural sources are generally limited and the isolation is very challenging. Additionally, the isolated polysaccharides are heterogeneous and often contains impurities. Furthermore, limited protection of certain CPS antigens impairs the efficiency of vaccines. To overcome limitations associated with isolated polysaccharides, synthetic oligosaccharides present an effective alternative with great potential to understand glycan immunology and rationally design effective antigens. Consequently, characterization and reconstruction of carbohydrate epitopes with authentic composition has become one of the major target in glycoscience. To this end, strategies are needed to facilitate the streamlined design and generation of these antigens. This thesis concerns the development of an effective synthetic strategy to obtain Group B Streptococcus (GBS) type II oligosaccharide for vaccine development. GBS, a Gram-positive bacterium, inhabits the intestinal and genitourinary tract of 10‐30% of humans. GBS is one of the primary causes of bacterial infections among neonates and pregnant women, resulting in many severe diseases such as sepsis, meningitis, abortion, and so on. Type II GBS is one of the predominant GBS serotypes and is associated with about 15% of the invasive infections in adults and infants; therefore, represents an important human pathogen. The development of effective preventive vaccine against GBS is much needed to help pregnant women protect their newborns. This thesis describes the effective synthetic strategy to synthesize GBS type II oligosaccharide to be applied for vaccine development. Herein, we present a new and convenient synthesis of the repeating unit of GBS type II capsular polysaccharide. The structure of GBS type II was elucidated in 1983 and the repeating unit of GBS type II is a heptasaccharide composed of α-Neu5Ac (2-3)-ß-D-Gal-(1-4)- ß-D-GlcNAc-(1-3)-[-ß-D-Gal-(1-6)]-ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc. The presented synthetic strategy is based on the five subcomponents derived from the retro synthetic analysis. Suitably protected lactosamine and lactose derivatives are pivotal building blocks in our synthesis and both disaccharide fragments have been achieved from the cheap and readily available lactose. Having started from two disaccharides saves the efforts of glycosylation and reduces the number of synthetic steps. The building blocks have been obtained in good overall yield following the optimized synthetic approach. The synthesis of backbone linear chain trisaccharide [ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc] and pentasaccharide [ß-D-Gal-(1-4)-ß-D-GlcNAc-(1-3)-ß-D-Gal-(1-4)-ß-D-Gal-(1-3)-ß-D-Glc] has been achieved in excellent yield (~80% yield). The final steps of the synthesis comprise- the incorporation of ß-D-Gal unit into the linear chain pentasaccharide (currently ongoing) followed by the enzymatic introduction of sialic acid (NeuNAc unit) and subsequent deprotection to yield the repeating unit of GBS type II capsular polysaccharide. To conclude, in this thesis we present an efficient and easy handling synthetic approach to the heptasaccharide repeating unit of GBS type II. Readily available and cheap dairy side-product lactose has been used as a key structure in the presented scheme, allowing the efficient synthesis of the pentasaccharide backbone of the target compound. The synthetic GBS II fragments will be used for glycan array and structural studies and immunochemical characterization with specific monoclonal antibodies. This thesis comprises of four main chapters and the experimental section containing the methods and synthetic procedures for the discussed schemes. Chapter one is a general introduction and deals with the necessity and the social importance of the described project. Chapter two of the thesis outlines the scientific background and pathogenesis of GBS, carbohydrates and their biological importance, and general introduction of vaccines and how the carbohydrates can be used as a suitable vaccine candidate. Chapter two establishes the importance of synthetic carbohydrates and how the synthetic carbohydrates can be used to develop suitable effective vaccines against GBS diseases. Chapter three of the thesis contains the general introduction and structural features of GBS II CPS and the retrosynthetic analysis of GBS II CPS to identify the building blocks for the synthesis of GBS CPS II. Chapter four of the thesis summarizes the synthetic strategies and results to achieve the building blocks described in chapter three and the recombination of fragments to achieve the final molecule GBS II CPS repeating unit. The last part of the thesis will consists of the experimental methods and synthetic procedures to achieve the proposed molecule along with the characterization data.
APA, Harvard, Vancouver, ISO, and other styles
2

Fusari, M. M. "SYNTHESIS OF FRAGMENTS OF SALMONELLA TYPHI CAPSULAR POLYSACCHARIDE AND THEIR ZWITTERIONIC ANALOGUES." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/243479.

Full text
Abstract:
Polysaccharide antigens are T cell-independent antigens, and do not induce immune B cell memory. Consequently, vaccines based on polysaccharides have limited clinical usefulness and induce short-lasting antibody responses in adults. Their immunogenicity can be enhanced by conjugation to an immunogenic carrier protein, generating T cell-dependent glycoconjugate antigens able to induce immunological memory. However, these glycoconjugates suffer from some problems. Recent investigations have found a group of structurally distinct bacterial polysaccharides able to activate T cells in vivo and in vitro. They present a zwitterionic charge motif distributed along the chain and, for this reason, they are called zwitterionic polysaccharides (ZPSs). This zwitterionic charge motif is believed to be responsible for their particular immunological behavior. The integrity of the zwitterionic motif is essential for the biological activity of ZPS. However, it must be clarified if the introduction of the zwitterionic motif into a naturally non-zwitterionic polysaccharide confers to the resulting ZPS the ability to activate T cells without protein conjugation. To this end, zwitterionic oligomers must be obtained by chemical modification of fully synthetic, non-zwitterionic polysaccharide fragments. With these compounds in hand it would be possible to correlate structural and conformational properties of the ZPS with their biological activity, in terms of charge pattern and minimum molecular weight required for immunogenicity. For this purpose the capsular polysaccharide (CPS) of Salmonella typhi was chosen as a suitable model for our investigation. S. typhi is an encapsulated Gram-negative bacterium that causes typhoid fever. Its CPS, commonly named Vi antigen, is an anionic polymer composed of alpha-(1-4)-linked N-acetylgalactosaminuronic acid repeating units predominantly O-acetylated at position 3. Recent studies indicated the importance of the acetylation for the immunogenicity. The structure of the Vi antigen makes it an ideal candidate for our investigation, since its fragments can be easily converted into zwitterionic derivatives by formal N-deacetylation, without introducing huge structural modifications. We designed a flexible synthetic strategy in order to obtain, from common building blocks, two distinct series of oligomers: the ones corresponding to the natural structure and their zwitterionic derivatives. Moreover, the role of 3-O-acetylation will be investigated by the synthesis of both fully 3-O-acetylated and fully 3-non-O-acetylated oligosaccharides. We selected N-phenyltrifluoroacetimidate moieties as the best leaving group in the glycosyl donors. Moreover, all the oligomers were endowed with a suitable linker at the anomeric position of the reducing end in order to facilitate subsequent conjugation to multivalent scaffolds. In the first part of the work the synthesis of oligomers non acetylated at position 3 is described. The glycosyl donor and acceptor were obtained from commercially available D-galactosamine hydrochloride. Their glycosylation was performed by a slow addition of a diluted solution of the Lewis acid via a syringe pump, and complete alpha stereoselectivity was obtained. We also successfully applied a more efficient elongation strategy based on disaccharide donors to the synthesis of the Vi trisaccharide and its zwitterionic derivative. Evaluation of the biological behavior of the target compounds was also performed by ELISA competitive assay. The second part of the work was focused on the synthesis of oligomers acetylated at C-3. In particular, a different approach based on pre-oxidized galacturonate building blocks obtained via inversion of C-4 configuration of commercially available D-glucosamine hydrochloride is described.
APA, Harvard, Vancouver, ISO, and other styles
3

Ruffing, Anne M. "Metabolic engineering and omics analysis of Agrobacterium sp. ATCC 31749 for oligosaccharide synthesis." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39507.

Full text
Abstract:
Oligosaccharides are important biomolecules that are targets and also components of many medical treatments, including treatments for cancer, HIV, and inflammation. While the demand for medically-relevant oligosaccharides is increasing, these compounds have proven difficult to synthesize. Whole-cell oligosaccharide synthesis is a promising method that requires relatively inexpensive substrates and can complete the synthesis in just one step. However, whole-cell oligosaccharide synthesis employing common microorganisms like E. coli have been plagued by low yields. This dissertation investigates an alternative microorganism for oligosaccharide production: Agrobacterium sp. ATCC 31749. This Agrobacterium strain produces high levels of curdlan polysaccharide, demonstrating its natural ability to produce the sugar nucleotide precursor for oligosaccharide production. The two main objectives of this dissertation are 1) to develop biocatalysts for oligosaccharide synthesis by engineering ATCC 31749 and 2) to determine what factors affect poly- and oligosaccharide production in this Agrobacterium strain. ATCC 31749 was engineered to produce two oligosaccharides of medical importance: N-acetyllactosamine and galactose-α 1,3-lactose. Oligosaccharide production in the biocatalyst was further improved with additional metabolic engineering. Substrate uptake was increased through expression of a lactose permease, and availability of the sugar nucleotide substrate improved with gene knockout of the curdlan synthase gene. Both of these engineering efforts led to increased oligosaccharide synthesis in the Agrobacterium biocatalyst. Overall, the engineered Agrobacterium strains synthesized gram-scale quantities of the oligosaccharide products in just one step and requiring only a few inexpensive substrates and cofactors. Additional improvement of the oligosaccharide-producing biocatalysts required further investigation of the factors influencing poly- and oligosaccharide production in ATCC 31749. In this dissertation, several environmental and intracellular factors are identified that affect both oligosaccharide and curdlan production. Sucrose was the preferred carbon source for oligosaccharide synthesis, and the addition of citrate to the synthesis reaction led to significant improvement in oligosaccharide production. To identify the genetic factors and possible mechanisms regulating curdlan production, the genome of ATCC 31749 was sequenced. The genome sequence was utilized for transcriptome analysis of ATCC 31749. In the transcriptome analysis, genes significantly up- and down-regulated during curdlan production were identified. Subsequent gene knockout experiments showed several factors to be important for curdlan synthesis, namely the nitrogen signaling cascade, polyphosphate, and the GTP-derived second messengers (p)ppGpp and c-di-GMP. In addition to the development of biocatalysts for oligosaccharide production, this investigation provides insight into the complex mechanisms regulating exopolysaccharide synthesis.
APA, Harvard, Vancouver, ISO, and other styles
4

Watts, Christopher Rohan. "Synthesis of complex oligosaccharide." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624487.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Le, Guen Yann. "Synthèse de fragments diversement acétylés des polysaccharides spécifiques des bactéries Shigella flexneri type I." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCB143.

Full text
Abstract:
Shigella flexneri est une entérobactérie Gram négatif responsable de la forme endémique de la shigellose, l’une des quatre causes majeures d’infection diarrhéique chez les jeunes enfants. La cible majeure de la réponse immunitaire lors d’une infection naturelle est le polysaccharide de surface (PS). Chez S. flexneri 1b, l’un des sérotypes prévalents dans les pays en voie de développement, le PS est défini par le pentasaccharide ramifié α-L-rhamnopyranosyl-(1→2)-α-L-rhamnopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→3)-[α-D-glucopyranosyl-(1→4)]-2-acetamido-2-deoxy-β-D-glucopyranoside [I] di-O-acétylé. Ces travaux s’intègrent dans un projet visant le développement d’un vaccin basé sur des sucres synthétiques à couverture large contre les infections par Shigella. Afin de concevoir des glycoconjugués efficaces et induisant une bonne réponse immunitaire chez les enfants, des synthèses multi-grammes des précurseurs mono- à pentasaccharidiques ont été optimisées permettant une stratégie par blocs en vue de l’obtention d’oligosaccharides de grande taille. Au cours de ces synthèses, l’obtention du trisaccharide ramifié C(E)D clé a nécessité de nombreuses optimisations, permettant la conception de synthons tri- à pentasaccharides. Un choix des groupements protecteurs orthogonaux nous a permis d’investiguer les différentes conditions de couplages nous donnant accès à 28 oligosaccharides déprotégés courts diversement acétylés. La validation de ces condensations avec des partenaires plus complexes a permis d’accéder à un large panel d’une cinquantaine d’oligosaccharides de di- à pentadécasaccharides sous leur forme libre, ou encore protégés avec divers degrés d’acétylation
700,000 children die each year due to diarrheal diseases, making it the second cause of death among this population. Shigella flexneri is a Gram negative enterobacterium responsible of the endemic form of shigellosis in developing countries. The O-antigen part of the bacterial lipopolysaccharide is the major target of the immune system during natural infection. The O-antigen of S. flexeni 1b, one of the prevalent serotypes, is defined by a ramified pentasaccharide made of three L-rhamnose, one D-glucosamine and one D-glucose with two non-stoichiometric sites for acetylation (I). This work is part of the project aimed at the development of a synthetic carbohydrate-based vaccine against Shigella infections. In order to obtain suitable glyconjugates inducing a high level of protection especially in children, the synthesis of mono- to pentasaccharide precursors was optimized, allowing a convergent synthesis of oligosaccharides with different acetylation patterns. Optimization of the glycosylation conditions, acetylations and protecting group manipulations enable the access to fragments from di to pentadecasaccharides representing S. flexneri type I O-antigen
APA, Harvard, Vancouver, ISO, and other styles
6

Drouin, Ludovic. "New methodology for oligosaccharide synthesis." Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444903.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Belogi, Gianluca. "Boronate esters in oligosaccharide synthesis." Thesis, University of Birmingham, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367628.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Patikis, Angela. "Enzymic studies of oligosaccharide synthesis." Thesis, University of Westminster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319626.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Davis, Nicola Jane. "Synthesis of sulphated oligosaccharides." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259866.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Nilsson, Magnus. "Chemical synthesis of oligosaccharide bacterial antigens /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5738-6.pdf.

Full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Oligosaccharide Synthesi"

1

Kováč, Pavol, ed. Synthetic Oligosaccharides. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Isles, Stephen John. Vinyl glycosides in oligosaccharide synthesis. Birmingham: University of Birmingham, 1996.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Horrobin, Tina M. The chemoenzymatic synthesis of oligosaccharides. [s.l.]: typescript, 1995.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

H, Khan Shaheer, and O'Neill Roger Alan, eds. Modern methods in carbohydrate synthesis. Amsterdam: Harwood Academic Publishers, 1996.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

J, Cristóbal López, and SpringerLink (Online service), eds. Reactivity Tuning in Oligosaccharide Assembly. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2011.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Hoh, Christoph. Reaktionstechnische Untersuchungen zur enzymatischen Glycosylierung von Peptiden. Jülich: Forschungszentrum Jülich, Zentralbibliothek, 2005.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

Veeneman, Gerrit Herman. Chemical synthesis of oligosaccharides in solution and on a solid support. [The Netherlands: s.n.], 1991.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

1938-, Friedman Robert B., American Chemical Society. Division of Carbohydrate Chemistry., American Chemical Society. Division of Agricultural and Food Chemistry., and American Chemical Society Meeting, eds. Biotechnology of amylodextrin oligosaccharides. Washington, DC: American Chemical Society, 1991.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

Driguez, Hugues, and Joachim Thiem, eds. Glycoscience Synthesis of Oligosaccharides and Glycoconjugates. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/bfb0119216.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

MacManus, D. A. Enzymatic synthesis of glycosides and oligosaccharides. [s.l.]: typescript, 1991.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Oligosaccharide Synthesi"

1

Boons, G. J. "Oligosaccharide Synthesis." In Organic Synthesis with Carbohydrates, 103–54. Sheffield, UK: Sheffield Academic Press Ltd, 2008. http://dx.doi.org/10.1002/9780470760321.ch4.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Lee, Y. C. "Synthetic Oligosaccharides In Glycobiology." In Synthetic Oligosaccharides, 2–18. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch001.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Petitou, M. "Drugs Based on Carbohydrates." In Synthetic Oligosaccharides, 19–35. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch002.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Backinowsky, L. V. "Sugar Cyanoethylidene Derivatives." In Synthetic Oligosaccharides, 36–50. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch003.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Grindley, T. Bruce. "Applications of Stannyl Ethers and Stannylene Acetals to Oligosaccharide Synthesis." In Synthetic Oligosaccharides, 51–76. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch004.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Lerner, Laura. "Flexibility of Biomolecules." In Synthetic Oligosaccharides, 77–88. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch005.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Petitou, M. "Synthetic Oligosaccharides as Probes for Investigating the Binding of Heparin to Antithrombin III." In Synthetic Oligosaccharides, 90–103. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch006.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Roy, R., D. Zanini, S. J. Meunier, and A. Romanowska. "Synthesis and Antigenic Properties of Sialic Acid Based Dendrimers." In Synthetic Oligosaccharides, 104–19. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch007.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Matta, Khushi L., Conrad F. Piskorz, Gurijala V. Reddy, E. V. Chandrasekaran, and Rakesh K. Jain. "Synthetic Acceptors for α-L-Fucosyltransferases." In Synthetic Oligosaccharides, 120–32. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch008.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Chernyak, A. Ya. "Oligosaccharide—Polyacrylamide Conjugates of Immunological Interest." In Synthetic Oligosaccharides, 133–56. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0560.ch009.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Oligosaccharide Synthesi"

1

Mardiguian, J. "IS PENTASACCHARIDE THE SMALLEST HEPARIN OLIGOSACCHARIDE WITH BINDING AFFINITY TO ANTITHROMBIN III ? AN OVERVIEW." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644849.

Full text
Abstract:
The binding of heparin to antithrombin III is ascribed to the presence in the heparin molecule of a specific binding site which contains a typical 3-0- sulfate group located on a glucosamine residue. It has been postulated that the smallest heparin oligosaccharide capable of high affinity binding to antithrombin III and eliciting anti-factor Xa activity is a pentasaccharide containing three glucosamine units and two uronic acid residues. Such a pentasaccharide has been recently isolated after chemical depolymerization of pig mucosal heparin and its structure found to be very close to that of a synthetic pentasaccharide prepared by other investigators. However no convincing data have, so far, excluded the possibility that an oligosaccharide composed of less than five sugar units could not be able to bind to antithrombinlll and to elicit anti-factor Xa activity. We report now the isolation of new oligosaccharides obtained by beta-eliminative chemical depolymerization of heparin using three different procedures : depolymerization of heparin benzyl ester (1) in aqueous medium and (2) in non-aqueous medium: (3) alcaline depolymerization of a periodate oxydized acetyl heparin. The data reported show that the high affinity oligosaccharides isolated after affinity chromatography on immobilized antithrombin III are distinct from the previously isolated pentasaccharide and that there is some evidence that these are tetrasaccharides resulting from the cleavage of the non reducing end of the heparin molecule
APA, Harvard, Vancouver, ISO, and other styles
2

Jahn, Michael, and Stephen G. Withers. "OLIGOSACCHARIDE SYNTHESIS USING MUTANT GLYCOSIDASES." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.424.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Manabe, Shino, Hiromune Ando, Shinya Hanashima, Yoshiaki Nakahara, and Yukishige Ito. "THE NOVEL METHODOLOGY FOR RAPID OLIGOSACCHARIDE SYNTHESIS." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.436.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Kanno, K., H. Maeda, S. Izumo, M. Ikuno, A. Tashiro, M. Miyazaki, and M. Fujii. "RAPID ENZYMATIC OLIGOSACCHARIDE SYNTHESIS IN MICROCHANNEL REACTOR." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.601.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Miura, Tsuyoshi, and Toshiyuki Inazu. "FLUOROUS OLIGOSACCHARIDE SYNTHESIS USING A NOVEL FLUOROUS PROTECTIVE GROUP." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.623.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Drinnan, Nicholas B., Laurent Bornaghi, and Michael L. West. "SOLID PHASE SYNTHESIS OF ALPHA-Gal CONTAINING OLIGOSACCHARIDES." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.647.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Mogemark, Mickael, Mikael Elofsson, and Jan Kihlberg. "QUANTITATIVE MONITORING OF SOLID-PHASE OLIGOSACCHARIDE SYNTHESIS WITH 19F NMR SPECTROSCOPY." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.625.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Seeberger, Peter H. "AUTOMATED SOLID PHASE SYNTHESIS OF OLIGOSACCHARIDES TO ADDRESS BIOMEDICAL PROBLEMS." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.364.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

SEEBERGER, PETER H. "AUTOMATED OLIGOSACCHARIDE SYNTHESIS: FROM INSIGHTS INTO FUNDAMENTAL GLYCOBIOLOGY TO VACCINES AND DIAGNOSTICS." In 23rd International Solvay Conference on Chemistry. WORLD SCIENTIFIC, 2014. http://dx.doi.org/10.1142/9789814603836_0020.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Unverzagt, Carlo. "GLYCOPROTEINS: STRATEGIES FOR THE SYNTHESIS OF THE OLIGOSACCHARIDE AND THE PROTEIN PART." In XXIst International Carbohydrate Symposium 2002. TheScientificWorld Ltd, 2002. http://dx.doi.org/10.1100/tsw.2002.373.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Oligosaccharide Synthesi"

1

Braunschweig, Adam B., Shudan Bian, and Han Xu. Carbohydrate Nanotechnology: Hierarchical Assemblies and Information Processing from Oligosaccharide-Synthetic Lectin Host-Guest. Fort Belvoir, VA: Defense Technical Information Center, September 2014. http://dx.doi.org/10.21236/ada612784.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Eyal, Yoram, Gloria Moore, and Efraim Lewinsohn. Study and Manipulation of the Flavanoid Biosynthetic Pathway in Citrus for Flavor Engineering and Seedless Fruit. United States Department of Agriculture, October 2003. http://dx.doi.org/10.32747/2003.7570547.bard.

Full text
Abstract:
The proposal was aimed to identify and functionally characterize key genes/enzymes in the citrus flavanone neohesperidoside biosynthetic pathway and to use them as tools for metabolic engineering to decrease bitterness levels in grapefruit. The proposed section on fruit seediness was dropped as suggested by the reviewers of the proposal. Citrus flavor and aroma is composed of complex combinations of soluble and volatile compounds. The former includes mainly sugars, acids and flavanones, a subgroup of flavonoids that includes bitter compounds responsible for the bitter flavor of grapefruit and pummelo. Bitter species contain mostly bitter flavanone neohesperidosides, while non-bitter species contain mostly tasteless flavanone rutinosides. Both flavanone versions are diglycosides consisting of a rhamnose-glucose oligosaccharide a-linked at position 7 to the flavanone skeleton. However, in the bitter neohesperidosides the rhamnose is attached at position 2 of the glucose moiety, while in the tasteless rutinosides the rhamnose is attached at position 6 of the glucose moiety. Thus, the position of the rhamnose moiety, determined by the specificity of the last enzymes in the pathway- rhamnosyltransferase (1,2 or 1,6 specificity), is the determinant of the bitter flavor. Flavanones, like all flavonoids are synthesized via one of the branches of the phenylpropanoid pathway; the first committed step is catalyzed by the enzyme Chalcone synthase (CHS) followed by Chalcone isomerase (CHI). During the course of the work a key gene/enzyme in the biosynthesis of the bitter flavanones, a 1,2 rhamnosyltransferase (1,2RT), was functionally characterized using a transgenic cell-culture biotransformation system, confirming that this gene is a prime candidate for metabolic engineering of the pathway. This is the first direct functional evidence for the activity of a plant recombinant rhamnosyltransferase, the first confirmed rhamnosyltransferase gene with 1,2 specificity and the second confirmed rhamnosyltransferase gene altogether in plants. Additional genes of the flavanone pathway that were isolated during this work and are potential tools for metabolic engineering include (I) A putative 1,6 rhamnosyltransferase (1,6RT) from oranges, that is presumed to catalyze the biosynthesis of the tasteless flavanones. This gene is a prime candidate for use in future metabolic engineering for decreased bitterness and is currently being functionally characterized using the biotransformation system developed for characterizing rhamnosyltransferases. (2) A putative 7-0-glucosyltransferase presumed to catalyze the first glycosylation step of the flavanone aglycones. Silencing of gene expression in grapefruit was attempted using three genes: (1) The "upstream" flavonoid biosynthesis genes CHS and CHI, by antisense and co-suppression; and (2) The "downstream" 1,2R T, by an RNAi approach. CHS and CHI silencing resulted in some plants with a dramatically decreased level of the bitter flavanone neohesperidoside naringin in leaves. We have yet to study the long-term effect of silencing these genes on tree physiology, and on the actual bitterness of fruit. The effect of 1,2RT silencing on naringin content in grapefruit has yet to be examined, but a slow growth phenotype for these plants was noted. We speculate that silencing of the final glycosylation step of the flavanones delays their evacuation to the vacuole, resulting in accumulation of flavanones in the cytoplasm, causing inhibitory effects on plant growth. This speculation is yet to be established at the product level. Future metabolic engineering experiments are planned with 1,6RT following functional characterization.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Oligosaccharide Synthesi' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography