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Articoli di riviste sul tema "Glycosidic bonds"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 19 febbraio 2022

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1

Wang, Qian, Chao Gao, Nan Yang e Katsuyoshi Nishinari. "Effect of simulated saliva components on the in vitro digestion of peanut oil body emulsion". RSC Advances 11, n. 49 (2021): 30520–31. http://dx.doi.org/10.1039/d1ra03274g.

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2

Joseleau, Jean-Paul, e Rachid Kesraoui. "Glycosidic Bonds between Lignin and Carbohydrates". Holzforschung 40, n. 3 (gennaio 1986): 163–68. http://dx.doi.org/10.1515/hfsg.1986.40.3.163.

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3

Johnson, Glenn P., Luis Petersen, Alfred D. French e Peter J. Reilly. "Twisting of glycosidic bonds by hydrolases". Carbohydrate Research 344, n. 16 (novembre 2009): 2157–66. http://dx.doi.org/10.1016/j.carres.2009.08.011.

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4

Khalilova, Gulnoza Abduvakhobovna, Abbaskhan Sabirkhanovich Turaev, Bahtiyor Ikromovich Muhitdinov, Albina Vasilevna Filatova, Saidakhon Bokijonovna Haytmetova e Nodirali Sokhobatalievich Normakhamatov. "Research On The Composition And Structure Of Β -Glucans Isolated From Basidiomycete Raw Materials Inonotus Hispidus". American Journal of Applied sciences 03, n. 01 (19 gennaio 2021): 9–17. http://dx.doi.org/10.37547/tajas/volume03issue01-03.

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This article highlights the conducted researches on the composition and structure of β-glucans isolated from the basidiomycete raw material Inonotus hispidus. By means of using the alditol acetate method, as well as by UV and IR methods, one-dimensional (13C NMR, 1H NMR), two-dimensional (1H-1H COSY, 1H-13C HSQC) NMR spectroscopy, the composition and molecular structure of polysaccharides were determined and their branching was proved. It was clarified that the composition of the polysaccharide fractions consists mainly of glucose residues (68-100%), as well as residues of fructose, xylose, mannose and galactose as minor monosaccharides. NMR spectroscopic studies of the specimens showed that the obtained polysaccharides consist of branched glucan structures linked by α- and β-glycosidic bonds. In the structure of β-glucans, the main chain is linked mainly through β-1,3-, partially β-1,4-glycosidic bonds, the branched parts consist of one or more β-D-glucose residues that are linked β-1,3- glycosidic bonds, as well as with the main chain, mainly through α- or β-1,6-glycosidic bonds. The results of the study of molecular parameters showed that the MW of β-glucans of basidiomycetes are in the range of 9100-9900 Da, MWD - 1.2-1.5.

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5

Weignerová, Lenka, Yukio Suzuki, Zdenka Huňková, Petr Sedmera, Vladimír Havlíček, Radek Marek e Vladimír Křen. "Pyridoxine as a Substrate for Screening Synthetic Potential of Glycosidases". Collection of Czechoslovak Chemical Communications 64, n. 8 (1999): 1325–34. http://dx.doi.org/10.1135/cccc19991325.

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The reactions of glycosidases with pyridoxine were used for testing their ability to make new glycosidic bonds. Of 35 glycosidases examined, some exhibited regiospecificity towards one primary alcoholic group; glycosylation of phenolic hydroxyl group was not observed. A series of new glycosides of pyridoxine, 2-acetamido-2-deoxy-β-D-glucopyranosides, α-D-manno- pyranosides, and one α-D-galactopyranoside were prepared and completely characterized by MS and NMR.

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6

Kobayashi, Hirokazu, Yusuke Suzuki, Takuya Sagawa, Kyoichi Kuroki, Jun-ya Hasegawa e Atsushi Fukuoka. "Impact of tensile and compressive forces on the hydrolysis of cellulose and chitin". Physical Chemistry Chemical Physics 23, n. 30 (2021): 15908–16. http://dx.doi.org/10.1039/d1cp01650d.

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7

Frański, R., P. Bednarek, D. Siatkowska, P. Wojtaszek e M. Stobiecki. "Application of mass spectrometry to structural identification of flavonoid monoglycosides isolated from shoot of lupin (Lupinus luteus L.)." Acta Biochimica Polonica 46, n. 2 (30 giugno 1999): 459–73. http://dx.doi.org/10.18388/abp.1999_4177.

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Flavonoid glycosides constitute important group of plant secondary metabolites. This class of natural products play significant role in different physiological processes. A new methodological approach where mass spectrometric techniques are applied to structural studies of this class of compounds is presented. Four flavonoid O-monoglycosides and one C-monoglycoside were isolated from green parts of lupin (Lupinus luteus L.). Several different mass spectrometric techniques were applied to structural elucidation of isolated compounds. Desorption ionization mass spectrometry was used for registration of mass spectra of intact and derivatized (permethylated) flavonoid glycosides. In some cases electron impact mass spectra of permethylated compounds were also recorded. Methylated samples after methanolysis and further derivatization of free hydroxyl groups (methylation or acetylation) were analyzed with gas chromatography-mass spectrometry. Combined information drawn from the registered mass spectra enabled us to define molecular mass, structure of aglycones and sugars, and positions of glycosidic bonds on the aglycon. Structures of four flavonoid monoglycosides were elucidated as follows: genistein 7-O-glucoside (1), genistein 4'-O-glucoside (2), 2'-hydroxygenistein 7-O-glucoside (3), and apigenin or genistein 8-C-glycoside (5). For the fourth O-glycoside (4) only molecular mass and masses of the aglycone and sugar were estimated.

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8

He, Xingxing, Fuyuan Zhang, Jifeng Liu, Guozhen Fang e Shuo Wang. "Homogenous graphene oxide-peptide nanofiber hybrid hydrogel as biomimetic polysaccharide hydrolase". Nanoscale 9, n. 45 (2017): 18066–74. http://dx.doi.org/10.1039/c7nr06525f.

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9

Davies, Gideon J., Simon J. Charnock e Bernard Henrissat. "The Enzymatic Synthesis of Glycosidic Bonds: "Glycosynthases" and Glycosyltransferases." Trends in Glycoscience and Glycotechnology 13, n. 70 (2001): 105–20. http://dx.doi.org/10.4052/tigg.13.105.

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10

Ibatullin, Farid M., Alexander M. Golubev, Leonid M. Firsov e Kirill N. Neustroev. "A model for cleavage ofO-glycosidic bonds in glycoproteins". Glycoconjugate Journal 10, n. 3 (giugno 1993): 214–18. http://dx.doi.org/10.1007/bf00702202.

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11

Moriyama, Takanori, e Hisami Ikeda. "Hydrolases acting on glycosidic bonds: chromatographic and electrophoretic separations". Journal of Chromatography B: Biomedical Sciences and Applications 684, n. 1-2 (settembre 1996): 201–16. http://dx.doi.org/10.1016/0378-4347(96)00148-x.

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12

van der Kaaij, R. M., X. L. Yuan, A. Franken, A. F. J. Ram, P. J. Punt, M. J. E. C. van der Maarel e L. Dijkhuizen. "Two Novel, Putatively Cell Wall-Associated and Glycosylphosphatidylinositol-Anchored α-Glucanotransferase Enzymes of Aspergillus niger". Eukaryotic Cell 6, n. 7 (11 maggio 2007): 1178–88. http://dx.doi.org/10.1128/ec.00354-06.

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ABSTRACT In the genome sequence of Aspergillus niger CBS 513.88, three genes were identified with high similarity to fungal α-amylases. The protein sequences derived from these genes were different in two ways from all described fungal α-amylases: they were predicted to be glycosylphosphatidylinositol anchored, and some highly conserved amino acids of enzymes in the α-amylase family were absent. We expressed two of these enzymes in a suitable A. niger strain and characterized the purified proteins. Both enzymes showed transglycosylation activity on donor substrates with α-(1,4)-glycosidic bonds and at least five anhydroglucose units. The enzymes, designated AgtA and AgtB, produced new α-(1,4)-glycosidic bonds and therefore belong to the group of the 4-α-glucanotransferases (EC 2.4.1.25). Their reaction products reached a degree of polymerization of at least 30. Maltose and larger maltooligosaccharides were the most efficient acceptor substrates, although AgtA also used small nigerooligosaccharides containing α-(1,3)-glycosidic bonds as acceptor substrate. An agtA knockout of A. niger showed an increased susceptibility towards the cell wall-disrupting compound calcofluor white, indicating a cell wall integrity defect in this strain. Homologues of AgtA and AgtB are present in other fungal species with α-glucans in their cell walls, but not in yeast species lacking cell wall α-glucan. Possible roles for these enzymes in the synthesis and/or maintenance of the fungal cell wall are discussed.

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13

Ipsen, Johan Ø., Magnus Hallas-Møller, Søren Brander, Leila Lo Leggio e Katja S. Johansen. "Lytic polysaccharide monooxygenases and other histidine-brace copper proteins: structure, oxygen activation and biotechnological applications". Biochemical Society Transactions 49, n. 1 (15 gennaio 2021): 531–40. http://dx.doi.org/10.1042/bst20201031.

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Lytic polysaccharide monooxygenases (LPMOs) are mononuclear copper enzymes that catalyse the oxidative cleavage of glycosidic bonds. They are characterised by two histidine residues that coordinate copper in a configuration termed the Cu-histidine brace. Although first identified in bacteria and fungi, LPMOs have since been found in all biological kingdoms. LPMOs are now included in commercial enzyme cocktails used in industrial biorefineries. This has led to increased process yield due to the synergistic action of LPMOs with glycoside hydrolases. However, the introduction of LPMOs makes control of the enzymatic step in industrial stirred-tank reactors more challenging, and the operational stability of the enzymes is reduced. It is clear that much is still to be learned about the interaction between LPMOs and their complex natural and industrial environments, and fundamental scientific studies are required towards this end. Several atomic-resolution structures have been solved providing detailed information on the Cu-coordination sphere and the interaction with the polysaccharide substrate. However, the molecular mechanisms of LPMOs are still the subject of intense investigation; the key question being how the proteinaceous environment controls the copper cofactor towards the activation of the O-O bond in O2 and cleavage of the glycosidic bonds in polysaccharides. The need for biochemical characterisation of each putative LPMO is discussed based on recent reports showing that not all proteins with a Cu-histidine brace are enzymes.

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14

Bissaro, Bastien, Pierre Monsan, Régis Fauré e Michael J. O’Donohue. "Glycosynthesis in a waterworld: new insight into the molecular basis of transglycosylation in retaining glycoside hydrolases". Biochemical Journal 467, n. 1 (20 marzo 2015): 17–35. http://dx.doi.org/10.1042/bj20141412.

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Carbohydrates are ubiquitous in Nature and play vital roles in many biological systems. Therefore the synthesis of carbohydrate-based compounds is of considerable interest for both research and commercial purposes. However, carbohydrates are challenging, due to the large number of sugar subunits and the multiple ways in which these can be linked together. Therefore, to tackle the challenge of glycosynthesis, chemists are increasingly turning their attention towards enzymes, which are exquisitely adapted to the intricacy of these biomolecules. In Nature, glycosidic linkages are mainly synthesized by Leloir glycosyltransferases, but can result from the action of non-Leloir transglycosylases or phosphorylases. Advantageously for chemists, non-Leloir transglycosylases are glycoside hydrolases, enzymes that are readily available and exhibit a wide range of substrate specificities. Nevertheless, non-Leloir transglycosylases are unusual glycoside hydrolases in as much that they efficiently catalyse the formation of glycosidic bonds, whereas most glycoside hydrolases favour the mechanistically related hydrolysis reaction. Unfortunately, because non-Leloir transglycosylases are almost indistinguishable from their hydrolytic counterparts, it is unclear how these enzymes overcome the ubiquity of water, thus avoiding the hydrolytic reaction. Without this knowledge, it is impossible to rationally design non-Leloir transglycosylases using the vast diversity of glycoside hydrolases as protein templates. In this critical review, a careful analysis of literature data describing non-Leloir transglycosylases and their relationship to glycoside hydrolase counterparts is used to clarify the state of the art knowledge and to establish a new rational basis for the engineering of glycoside hydrolases.

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15

Zhang, Lilan, Puya Zhao, Chun-Chi Chen, Chun-Hsiang Huang, Tzu-Ping Ko, Yingying Zheng e Rey-Ting Guo. "Preliminary X-ray diffraction analysis of a thermophilic β-1,3–1,4-glucanase fromClostridium thermocellum". Acta Crystallographica Section F Structural Biology Communications 70, n. 7 (19 giugno 2014): 946–48. http://dx.doi.org/10.1107/s2053230x14009376.

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β-1,3–1,4-Glucanases catalyze the specific hydrolysis of internal β-1,4-glycosidic bonds adjacent to the 3-O-substituted glucose residues in mixed-linked β-glucans. The thermophilic glycoside hydrolase CtGlu16A fromClostridium thermocellumexhibits superior thermal profiles, high specific activity and broad pH adaptability. Here, the catalytic domain of CtGlu16A was expressed inEscherichia coli, purified and crystallized in the trigonal space groupP3121, with unit-cell parametersa=b= 74.5,c= 182.9 Å, by the sitting-drop vapour-diffusion method and diffracted to 1.95 Å resolution. The crystal contains two protein molecules in an asymmetric unit. Further structural determination and refinement are in progress.

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16

Müller, Jens. "Metal-mediated base pairs in parallel-stranded DNA". Beilstein Journal of Organic Chemistry 13 (13 dicembre 2017): 2671–81. http://dx.doi.org/10.3762/bjoc.13.265.

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In nucleic acid chemistry, metal-mediated base pairs represent a versatile method for the site-specific introduction of metal-based functionality. In metal-mediated base pairs, the hydrogen bonds between complementary nucleobases are replaced by coordinate bonds to one or two transition metal ions located in the helical core. In recent years, the concept of metal-mediated base pairing has found a significant extension by applying it to parallel-stranded DNA duplexes. The antiparallel-stranded orientation of the complementary strands as found in natural B-DNA double helices enforces a cisoid orientation of the glycosidic bonds. To enable the formation of metal-mediated base pairs preferring a transoid orientation of the glycosidic bonds, parallel-stranded duplexes have been investigated. In many cases, such as the well-established cytosine–Ag(I)–cytosine base pair, metal complex formation is more stabilizing in parallel-stranded DNA than in antiparallel-stranded DNA. This review presents an overview of all metal-mediated base pairs reported as yet in parallel-stranded DNA, compares them with their counterparts in regular DNA (where available), and explains the experimental conditions used to stabilize the respective parallel-stranded duplexes.

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17

Rohlenová, Anna, Miroslav Ledvina, David Šaman e Karel Bezouška. "Synthesis of Linear and Branched Regioisomeric Chitooligosaccharides as Potential Mimetics of Natural Oligosaccharide Ligands of Natural Killer Cells NKR-P1 and CD69 Lectin Receptors". Collection of Czechoslovak Chemical Communications 69, n. 9 (2004): 1781–804. http://dx.doi.org/10.1135/cccc20041781.

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Regioisomer of chitobiose 13 with β(1→3) glycosidic bond and branched analog of chitotriose 25 having β(1→4) and β(1→3) glycosidic bonds, were prepared and tested as potential mimetics of natural oligosaccharide ligands for activating lectin receptors NKR-P1A and CD69 of natural killer (NK) cells. The structural requirements of NKR-P1 lectin receptor on effective mimetics of its natural ligands has been discussed. A significant binding activity of the branched trisaccharide 25 to the receptor CD69 was observed.

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18

Chaube, Manishkumar A., e Suvarn S. Kulkarni. "ChemInform Abstract: Stereoselective Construction of 1,1-α,α-Glycosidic Bonds". ChemInform 43, n. 41 (13 settembre 2012): no. http://dx.doi.org/10.1002/chin.201241251.

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19

Mihelič, Marko, Kristina Vlahoviček-Kahlina, Miha Renko, Stephane Mesnage, Andreja Doberšek, Ajda Taler-Verčič, Andreja Jakas e Dušan Turk. "The mechanism behind the selection of two different cleavage sites in NAG-NAM polymers". IUCrJ 4, n. 2 (23 febbraio 2017): 185–98. http://dx.doi.org/10.1107/s2052252517000367.

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Peptidoglycan is a giant molecule that forms the cell wall that surrounds bacterial cells. It is composed of alternatingN-acetylglucosamine (NAG) andN-acetylmuramic acid (NAM) residues connected by β-(1,4)-glycosidic bonds and cross-linked with short polypeptide chains. Owing to the increasing antibiotic resistance against drugs targeting peptidoglycan synthesis, studies of enzymes involved in the degradation of peptidoglycan, such asN-acetylglucosaminidases, may expose new, valuable drug targets. The scientific challenge addressed here is how lysozymes, muramidases which are likely to be the most studied enzymes ever, and bacterialN-acetylglucosaminidases discriminate between two glycosidic bonds that are different in sequence yet chemically equivalent in the same NAG-NAM polymers. In spite of more than fifty years of structural studies of lysozyme, it is still not known how the enzyme selects the bond to be cleaved. Using macromolecular crystallography, chemical synthesis and molecular modelling, this study explains how these two groups of enzymes based on an equivalent structural core exhibit a difference in selectivity. The crystal structures ofStaphylococcus aureusN-acetylglucosaminidase autolysin E (AtlE) alone and in complex with fragments of peptidoglycan revealed thatN-acetylglucosaminidases and muramidases approach the substrate at alternate glycosidic bond positions from opposite sides. The recognition pocket for NAM residues in the active site ofN-acetylglucosaminidases may make them a suitable drug target.

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Striegler, Susanne, Qiu-Hua Fan e Nigam P. Rath. "Binuclear copper(II) complexes discriminating epimeric glycosides and α- and β-glycosidic bonds in aqueous solution". Journal of Catalysis 338 (giugno 2016): 349–64. http://dx.doi.org/10.1016/j.jcat.2015.12.026.

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21

Maliekkal, Vineet, Saurabh Maduskar, Derek J. Saxon, Mohammadreza Nasiri, Theresa M. Reineke, Matthew Neurock e Paul Dauenhauer. "Activation of Cellulose via Cooperative Hydroxyl-Catalyzed Transglycosylation of Glycosidic Bonds". ACS Catalysis 9, n. 3 (31 dicembre 2018): 1943–55. http://dx.doi.org/10.1021/acscatal.8b04289.

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22

Panzeter, Phyllis L., Barbara Zweifel e Felix R. Althaus. "The α-glycosidic bonds of poly(ADP-ribose) are acid-labile". Biochemical and Biophysical Research Communications 184, n. 1 (aprile 1992): 544–48. http://dx.doi.org/10.1016/0006-291x(92)91229-j.

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23

El Ashry, El Sayed H., e Mohamed R. E. Aly. "Synthesis and biological relevance of N-acetylglucosamine-containing oligosaccharides". Pure and Applied Chemistry 79, n. 12 (1 gennaio 2007): 2229–42. http://dx.doi.org/10.1351/pac200779122229.

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The structural diversity as well as the biological significance of N-acetylglucosamine-containing glycans are exemplified. The problem of forming the respective glycosidic bonds of synthetic targets is addressed. Special emphasis has been given to human milk oligosaccharides (HMOs), in view of their biological relevance, and synthetic approaches of selected examples are reported.

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Pote, Aditya R., Sergi Pascual, Antoni Planas e Mark W. Peczuh. "Indolyl Septanoside Synthesis for In Vivo Screening of Bacterial Septanoside Hydrolases". International Journal of Molecular Sciences 22, n. 9 (26 aprile 2021): 4497. http://dx.doi.org/10.3390/ijms22094497.

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Building-up and breaking-down of carbohydrates are processes common to all forms of life. Glycoside hydrolases are a broad class of enzymes that play a central role in the cleavage of glycosidic bonds, which is fundamental to carbohydrate degradation. The large majority of substrates are five- and six-membered ring glycosides. Our interest in seven-membered ring septanose sugars has inspired the development of a way to search for septanoside hydrolase activity. Described here is a strategy for the discovery of septanoside hydrolases that uses synthetic indolyl septanosides as chromogenic substrates. Access to these tool compounds was enabled by a route where septanosyl halides act as glycosyl donors for the synthesis of the indolyl septanosides. The screening strategy leverages the known dimerization of 3-hydroxy-indoles to make colored dyes, as occurs when the β-galactosidase substrate X-Gal is hydrolyzed. Because screens in bacterial cells would enable searches in organisms that utilize heptoses or from metagenomics libraries, we also demonstrate that septanosides are capable of entering E. coli cells through the use of a BODIPY-labeled septanoside. The modularity of the indolyl septanoside synthesis should allow the screening of a variety of substrates that mimic natural structures via this general approach.

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Zhang, Xiaochen, Zhe Zhang, Feng Wang, Yehong Wang, Qi Song e Jie Xu. "Lignosulfonate-based heterogeneous sulfonic acid catalyst for hydrolyzing glycosidic bonds of polysaccharides". Journal of Molecular Catalysis A: Chemical 377 (ottobre 2013): 102–7. http://dx.doi.org/10.1016/j.molcata.2013.05.001.

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Pinto, José-Henrique Q., e Serge Kaliaguine. "A Monte Carlo analysis of acid hydrolysis of glycosidic bonds in polysaccharides". AIChE Journal 37, n. 6 (giugno 1991): 905–14. http://dx.doi.org/10.1002/aic.690370613.

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Fan, Jingjing, Minghao Zhang, Zhiyi Ai, Jing Huang, Yonghong Wang, Shengyuan Xiao e Yuhua Wang. "Highly regioselective hydrolysis of the glycosidic bonds in ginsenosides catalyzed by snailase". Process Biochemistry 103 (aprile 2021): 114–22. http://dx.doi.org/10.1016/j.procbio.2021.02.013.

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Southwick, Audrey M., Lai-Xi Wang, Sharon R. Long e Yuan C. Lee. "Activity of Sinorhizobium meliloti NodAB and NodH Enzymes on Thiochitooligosaccharides". Journal of Bacteriology 184, n. 14 (15 luglio 2002): 4039–43. http://dx.doi.org/10.1128/jb.184.14.4039-4043.2002.

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ABSTRACT Rhizobium bacteria synthesize signal molecules called Nod factors that elicit responses in the legume root during nodulation. Nod factors, modified N-acylated β-(1,4)-N-acetylglucosamine, are synthesized by the nodulation (nod) gene products. We tested the ability of three Sinorhizobium meliloti nod gene products to modify Nod factor analogs with thio linkages instead of O-glycosidic bonds in the oligosaccharide backbone.

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Frandsen, Kristian E. H., Jens-Christian Navarro Poulsen, Morten Tovborg, Katja S. Johansen e Leila Lo Leggio. "Learning from oligosaccharide soaks of crystals of an AA13 lytic polysaccharide monooxygenase: crystal packing, ligand binding and active-site disorder". Acta Crystallographica Section D Structural Biology 73, n. 1 (1 gennaio 2017): 64–76. http://dx.doi.org/10.1107/s2059798316019641.

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Lytic polysaccharide monooxygenases (LPMOs) are a class of copper-dependent enzymes discovered within the last ten years. They oxidatively cleave polysaccharides (chitin, lignocellulose, hemicellulose and starch-derived), presumably making recalcitrant substrates accessible to glycoside hydrolases. Recently, the first crystal structure of an LPMO–substrate complex was reported, giving insights into the interaction of LPMOs with β-linked substrates (Frandsenet al., 2016). The LPMOs acting on α-linked glycosidic bonds (family AA13) display binding surfaces that are quite different from those of LPMOs that act on β-linked glycosidic bonds (families AA9–AA11), as revealed from the first determined structure (Lo Leggioet al., 2015), and thus presumably the AA13s interact with their substrate in a distinct fashion. Here, several new structures of the same AA13 enzyme,Aspergillus oryzaeAA13, are presented. Crystals obtained in the presence of high zinc-ion concentrations were used, as they can be obtained more reproducibly than those used to refine the deposited copper-containing structure. One structure with an ordered zinc-bound active site was solved at 1.65 Å resolution, and three structures from crystals soaked with maltooligosaccharides in solutions devoid of zinc ions were solved at resolutions of up to 1.10 Å. Despite similar unit-cell parameters, small rearrangements in the crystal packing occur when the crystals are depleted of zinc ions, resulting in a more occluded substrate-binding surface. In two of the three structures maltooligosaccharide ligands are bound, but not at the active site. Two of the structures presented show a His-ligand conformation that is incompatible with metal-ion binding. In one of these structures this conformation is the principal one (80% occupancy), giving a rare atomic resolution view of a substantially misfolded enzyme that is presumably rendered inactive.

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Iakiviak, Michael, Roderick I. Mackie e Isaac K. O. Cann. "Functional Analyses of Multiple Lichenin-Degrading Enzymes from the Rumen Bacterium Ruminococcus albus 8". Applied and Environmental Microbiology 77, n. 21 (2 settembre 2011): 7541–50. http://dx.doi.org/10.1128/aem.06088-11.

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ABSTRACTRuminococcus albus8 is a fibrolytic ruminal bacterium capable of utilization of various plant cell wall polysaccharides. A bioinformatic analysis of a partial genome sequence ofR. albusrevealed several putative enzymes likely to hydrolyze glucans, including lichenin, a mixed-linkage polysaccharide of glucose linked together in β-1,3 and β-1,4 glycosidic bonds. In the present study, we demonstrate the capacity of four glycoside hydrolases (GHs), derived fromR. albus, to hydrolyze lichenin. Two of the genes encoded GH family 5 enzymes (Ra0453 and Ra2830), one gene encoded a GH family 16 enzyme (Ra0505), and the last gene encoded a GH family 3 enzyme (Ra1595). Each gene was expressed inEscherichia coli, and the recombinant protein was purified to near homogeneity. Upon screening on a wide range of substrates, Ra0453, Ra2830, and Ra0505 displayed different hydrolytic properties, as they released unique product profiles. The Ra1595 protein, predicted to function as a β-glucosidase, preferred cleavage of a nonreducing end glucose when linked by a β-1,3 glycosidic bond to the next glucose residue. The major product of Ra0505 hydrolysis of lichenin was predicted to be a glucotriose that was degraded only by Ra0453 to glucose and cellobiose. Most importantly, the four enzymes functioned synergistically to hydrolyze lichenin to glucose, cellobiose, and cellotriose. This lichenin-degrading enzyme mix should be of utility as an additive to feeds administered to monogastric animals, especially those high in fiber.

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Oana, Cioanca, Trifan Adriana, Cornelia Mircea, Scripcariu Dragos e Hancianu Monica. "Natural Macromolecules with Protective and Antitumor Activity". Anti-Cancer Agents in Medicinal Chemistry 18, n. 5 (21 agosto 2018): 675–83. http://dx.doi.org/10.2174/1871520618666180425115029.

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This review summarizes the literature data regarding plant lectins as novel drug sources in the prevention or treatment of cancer. Moreover, such compounds have been described as natural toxins that possess different biological activities (cytotoxic, antitumor, antimutagenic and anticarcinogenic properties). This activity depends greatly on their structure and affinity. Most of the mushroom heterosides are known as β-glucans with β-(1→3)-glycosidic bonds. It is thought that their conformation, bonds, molecular size can modulate the immune response by triggering different receptors. The mechanism on normal and tumor cells of various plant and mushroom polysaccharides and lectins is briefly presented in this paper.

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Engelen, Adrianus J., Fred C. Van Der Heeft e Peter H. G. Randsdorp. "Viscometric Determination of p-Glucanase and Endoxylanase Activity in Feed". Journal of AOAC INTERNATIONAL 79, n. 5 (1 settembre 1996): 1019–25. http://dx.doi.org/10.1093/jaoac/79.5.1019.

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Abstract A method is described for viscometric determination of enzymatic activity of β-glucanase and endoxylanase in feed samples. The method is based on determination of the decrease in viscosity as a result of hydrolysis of glycosidic bonds in β-glucan and xylan at pH 3.5. This method does not require a blank sample (feed without enzyme addition), and it does not need standard addition for reliable quantitation.

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Goddat, J. "Synthesis of di- and tri-saccharides with intramolecular NH-glycosidic linkages: molecules with flexible and rigid glycosidic bonds for conformational studies". Carbohydrate Research 252, n. 1 (15 gennaio 1994): 159–70. http://dx.doi.org/10.1016/0008-6215(94)84130-6.

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Goddat, Jacqueline, Arthur A. Grey, Milos Hricovíni, Jeremy Grushcow, Jeremy P. Carver e Rajan N. Shah. "Synthesis of di- and tri-saccharides with intramolecular NH-glycosidic linkages: molecules with flexible and rigid glycosidic bonds for conformational studies". Carbohydrate Research 252 (gennaio 1994): 159–70. http://dx.doi.org/10.1016/0008-6215(94)90013-2.

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35

Li, Kaixin, Limin Deng, Shun Yi, Yabo Wu, Guangjie Xia, Jun Zhao, Dong LU e Yonggang Min. "Boosting the performance by the water solvation shell with hydrogen bonds on protonic ionic liquids: insights into the acid catalysis of the glycosidic bond". Catalysis Science & Technology 11, n. 10 (2021): 3527–38. http://dx.doi.org/10.1039/d0cy02459g.

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36

Islam, Nazrul, Hui Wang, Faheem Maqbool e Vito Ferro. "In Vitro Enzymatic Digestibility of Glutaraldehyde-Crosslinked Chitosan Nanoparticles in Lysozyme Solution and Their Applicability in Pulmonary Drug Delivery". Molecules 24, n. 7 (1 aprile 2019): 1271. http://dx.doi.org/10.3390/molecules24071271.

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Herein, the degradation of low molecular weight chitosan (CS), with 92% degree of deacetylation (DD), and its nanoparticles (NP) has been investigated in 0.2 mg/mL lysozyme solution at 37 °C. The CS nanoparticles were prepared using glutaraldehyde crosslinking of chitosan in a water-in-oil emulsion system. The morphological characterization of CS particles was carried out using scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques. Using attenuated total reflectance Fourier transform infrared (ATR-FTIR) and UV-VIS spectroscopy, the structural integrity of CS and its NPs in lysozyme solution were monitored. The CS powder showed characteristic FTIR bands around 1150 cm−1 associated with the glycosidic bridges (C-O-C bonds) before and after lysozyme treatment for 10 weeks, which indicated no CS degradation. The glutaraldehyde crosslinked CS NPs showed very weak bands associated with the glycosidic bonds in lysozyme solution. Interestingly, the UV-VIS spectroscopic data showed some degradation of CS NPs in lysozyme solution. The results of this study indicate that CS with a high DD and its NPs crosslinked with glutaraldehyde were not degradable in lysozyme solution and thus unsuitable for pulmonary drug delivery. Further studies are warranted to understand the complete degradation of CS and its NPs to ensure their application in pulmonary drug delivery.

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de Ruyck, Jerome, Marc F. Lensink e Julie Bouckaert. "Structures ofC-mannosylated anti-adhesives bound to the type 1 fimbrial FimH adhesin". IUCrJ 3, n. 3 (26 febbraio 2016): 163–67. http://dx.doi.org/10.1107/s2052252516002487.

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Selective inhibitors of the type 1 fimbrial adhesin FimH are recognized as attractive alternatives for antibiotic therapies and prophylaxes againstEscherichia coliinfections such as urinary-tract infections. To construct these inhibitors, the α-D-mannopyranoside of high-mannoseN-glycans, recognized with exclusive specificity on glycoprotein receptors by FimH, forms the basal structure. A hydrophobic aglycon is then linked to the mannose by the O1 oxygen inherently present in the α-anomeric configuration. Substitution of this O atom by a carbon introduces aC-glycosidic bond, which may enhance the therapeutic potential of such compounds owing to the inability of enzymes to degradeC-glycosidic bonds. Here, the first crystal structures of theE. coliFimH adhesin in complex withC-glycosidically linked mannopyranosides are presented. These findings explain the role of the spacer in positioning biphenyl ligands for interactions by means of aromatic stacking in the tyrosine gate of FimH and how the normally hydratedC-glycosidic link is tolerated. As these new compounds can bind FimH, it can be assumed that they have the potential to serve as potent new antagonists of FimH, paving the way for the design of a new family of anti-adhesive compounds against urinary-tract infections.

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Damián-Almazo, Juanita Yazmin, Alina Moreno, Agustin López-Munguía, Xavier Soberón, Fernando González-Muñoz e Gloria Saab-Rincón. "Enhancement of the Alcoholytic Activity of α-Amylase AmyA from Thermotoga maritima MSB8 (DSM 3109) by Site-Directed Mutagenesis". Applied and Environmental Microbiology 74, n. 16 (13 giugno 2008): 5168–77. http://dx.doi.org/10.1128/aem.00121-08.

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ABSTRACT AmyA, an α-amylase from the hyperthermophilic bacterium Thermotoga maritima, is able to hydrolyze internal α-1,4-glycosidic bonds in various α-glucans at 85°C as the optimal temperature. Like other glycoside hydrolases, AmyA also catalyzes transglycosylation reactions, particularly when oligosaccharides are used as substrates. It was found that when methanol or butanol was used as the nucleophile instead of water, AmyA was able to catalyze alcoholysis reactions. This capability has been evaluated in the past for some α-amylases, with the finding that only the saccharifying fungal amylases from Aspergillus niger and from Aspergillus oryzae present measurable alcoholysis activity (R. I. Santamaria, G. Del Rio, G. Saab, M. E. Rodriguez, X. Soberon, and A. Lopez, FEBS Lett. 452:346-350, 1999). In the present work, we found that AmyA generates larger quantities of alkyl glycosides than any amylase reported so far. In order to increase the alcoholytic activity observed in AmyA, several residues were identified and mutated based on previous analogous positions in amylases, defining the polarity and geometry of the active site. Replacement of residue His222 by glutamine generated an increase in the alkyl glucoside yield as a consequence of a higher alcoholysis/hydrolysis ratio. The same change in specificity was observed for the mutants H222E and H222D, but instability of these mutants toward alcohols decreased the yield of alkyl glucoside.

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BORASTON, Alisdair B., David N. BOLAM, Harry J. GILBERT e Gideon J. DAVIES. "Carbohydrate-binding modules: fine-tuning polysaccharide recognition". Biochemical Journal 382, n. 3 (7 settembre 2004): 769–81. http://dx.doi.org/10.1042/bj20040892.

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The enzymic degradation of insoluble polysaccharides is one of the most important reactions on earth. Despite this, glycoside hydrolases attack such polysaccharides relatively inefficiently as their target glycosidic bonds are often inaccessible to the active site of the appropriate enzymes. In order to overcome these problems, many of the glycoside hydrolases that utilize insoluble substrates are modular, comprising catalytic modules appended to one or more non-catalytic CBMs (carbohydrate-binding modules). CBMs promote the association of the enzyme with the substrate. In view of the central role that CBMs play in the enzymic hydrolysis of plant structural and storage polysaccharides, the ligand specificity displayed by these protein modules and the mechanism by which they recognize their target carbohydrates have received considerable attention since their discovery almost 20 years ago. In the last few years, CBM research has harnessed structural, functional and bioinformatic approaches to elucidate the molecular determinants that drive CBM–carbohydrate recognition. The present review summarizes the impact structural biology has had on our understanding of the mechanisms by which CBMs bind to their target ligands.

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40

Fleming, Kelly L., e Jim Pfaendtner. "Characterizing the Catalyzed Hydrolysis of β-1,4 Glycosidic Bonds Using Density Functional Theory". Journal of Physical Chemistry A 117, n. 51 (10 dicembre 2013): 14200–14208. http://dx.doi.org/10.1021/jp4081178.

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41

Sørensen, Trine Holst, Nicolaj Cruys-Bagger, Kim Borch e Peter Westh. "Free Energy Diagram for the Heterogeneous Enzymatic Hydrolysis of Glycosidic Bonds in Cellulose". Journal of Biological Chemistry 290, n. 36 (16 luglio 2015): 22203–11. http://dx.doi.org/10.1074/jbc.m115.659656.

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42

Chen, Yun, Jian-Wen Huang, Chun-Chi Chen, Hui-Lin Lai, Jian Jin e Rey-Ting Guo. "Crystallization and preliminary X-ray diffraction analysis of an endo-1,4-β-D-glucanase fromAspergillus aculeatusF-50". Acta Crystallographica Section F Structural Biology Communications 71, n. 4 (20 marzo 2015): 397–400. http://dx.doi.org/10.1107/s2053230x15003659.

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Abstract (sommario):

Cellulose is the most abundant renewable biomass on earth, and its decomposition has proven to be very useful in a wide variety of industries. Endo-1,4-β-D-glucanase (EC 3.2.1.4; endoglucanase), which can catalyze the random hydrolysis of β-1,4-glycosidic bonds to cleave cellulose into smaller fragments, is a key cellulolytic enzyme. An endoglucanase isolated fromAspergillus aculeatusF-50 (FI-CMCase) that was classified into glycoside hydrolase family 12 has been found to be effectively expressed in the industrial strainPichia pastoris. Here, recombinant FI-CMCase was crystallized. Crystals belonging to the orthorhombic space groupC2221, with unit-cell parametersa= 74.2,b= 75.1,c= 188.4 Å, were obtained by the sitting-drop vapour-diffusion method and diffracted to 1.6 Å resolution. Initial phase determination by molecular replacement clearly shows that the crystal contains two protein molecules in the asymmetric unit. Further model building and structure refinement are in progress.

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43

Nemzer, Boris V., Diganta Kalita, Alexander Ya Yashin, Nikolay E. Nifantiev e Yakov I. Yashin. "In vitro Antioxidant Activities of Natural Polysaccharides: An overview". Journal of Food Research 8, n. 6 (29 ottobre 2019): 78. http://dx.doi.org/10.5539/jfr.v8n6p78.

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Polysaccharides are naturally occurring biomacromolecules composed of carbohydrate molecules linked by glycosidic bonds. A number of polysaccharides are known to possess beneficial therapeutic effects against inflammation, diabetes, cardiovascular diseases, and cancers. Indeed, polysaccharides are reportedly effective free radical scavengers and antioxidants, thereby playing a critical role in the prevention of damage to living organisms under oxidative stress. In this review we provide an overview of the sources, extraction, and antioxidant activities of some natural polysaccharides.

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44

Nifantiev, N. E., A. A. Sherman, O. N. Yudina, P. E. Cheshev, Y. E. Tsvetkov, E. A. Khatuntseva, A. V. Kornilov e A. S. Shashkov. "New schemes for the synthesis of glycolipid oligosaccharide chains". Pure and Applied Chemistry 76, n. 9 (30 settembre 2004): 1705–14. http://dx.doi.org/10.1351/pac200476091705.

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The driving force for the constant improvement and development of synthetic methodologies in carbohydrate chemistry is the importance of natural oligosaccharide chains in numerous biological phenomena such as cell growth, differentiation, adhesion, etc. Here, we report our syntheses of the spacer-armed oligosaccharides of sialylated lacto- and neo- lacto-, globo-, ganglio-, and sulfoglucuronylparagloboside-series, which include new rationally designed synthetic blocks, efficient solutions for the stereoselective construction of glycosidic bonds, and novel protection group strategies.

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Davies, Gideon J., e Spencer J. Williams. "Carbohydrate-active enzymes: sequences, shapes, contortions and cells". Biochemical Society Transactions 44, n. 1 (9 febbraio 2016): 79–87. http://dx.doi.org/10.1042/bst20150186.

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Abstract (sommario):

The enzyme-catalysed degradation of oligo and polysaccharides is of considerable interest in many fields ranging from the fundamental–understanding the intrinsic chemical beauty–through to the applied, including diverse practical applications in medicine and biotechnology. Carbohydrates are the most stereochemically-complex biopolymer, and myriad different natural polysaccharides have led to evolution of multifaceted enzyme consortia for their degradation. The glycosidic bonds that link sugar monomers are among the most chemically-stable, yet enzymatically-labile, bonds in the biosphere. That glycoside hydrolases can achieve a rate enhancement (kcat/kuncat) >1017-fold provides testament to their remarkable proficiency and the sophistication of their catalysis reaction mechanisms. The last two decades have seen significant advances in the discovery of new glycosidase sequences, sequence-based classification into families and clans, 3D structures and reaction mechanisms, providing new insights into enzymatic catalysis. New impetus to these studies has been provided by the challenges inherent in plant and microbial polysaccharide degradation, both in the context of environmentally-sustainable routes to foods and biofuels, and increasingly in human nutrition. Study of the reaction mechanism of glycoside hydrolases has also inspired the development of enzyme inhibitors, both as mechanistic probes and increasingly as therapeutic agents. We are on the cusp of a new era where we are learning how to dovetail powerful computational techniques with structural and kinetic data to provide an unprecedented view of conformational details of enzyme action.

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Liu, Ping, Jiao Xue, Shisheng Tong, Wenxia Dong e Peipei Wu. "Structure Characterization and Hypoglycaemic Activities of Two Polysaccharides from Inonotus obliquus". Molecules 23, n. 8 (4 agosto 2018): 1948. http://dx.doi.org/10.3390/molecules23081948.

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In the present study, two polysaccharides (HIOP1-S and HIOP2-S) were isolated and purified from Inonotus obliquus using DEAE-52 cellulose and Sephadex G-100 column chromatography. The structural characterization and in vitro and in vivo hypoglycaemic activities of these molecules were investigated. HPLC analysis HIOP1-S was a heterpolysaccharide with glucose and galactose as the main compontent monosaccharides (50.247%, molar percentages). However, HIOP2-S was a heterpolysaccharide with glucose as the main monosaccharide (49.881%, molar percentages). The average molecular weights of HIOP1-S and HIOP2-S were 13.6 KDa and 15.2 KDa, respectively. The β-type glycosidic bond in HIOP1-S and HIOP2-S was determined using infrared analysis. 1H-NMR spectra indicated that HIOP2-S contains the β-configuration glycosidic bond, and the glycoside bonds of HIOP1-S are both α-type and β-type. The ultraviolet scanning showed that both HIOP1-S and HIOP2-S contained a certain amount of binding protein. Congo red test showed that HIOP1-S and HIOP2-S could form a regular ordered triple helix structure in the neutral and weakly alkaline range. HIOP1-S and HIOP2-S showed strong α-glucosidase inhibitory activities and increased the glucose consumption of HepG2 cells. In addition, Streptozotocin (STZ)-induced hyperglycaemic mice were used to evaluate the antihyperglycaemic effects of HIOP1-S and HIOP2-S in vivo. The results showed that HIOP2-S had antihyperglycaemic effects. Taken together, these results suggest that HIOP1-S and HIOP2-S have potential anti-diabetic effects.

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Tremmel, Martina, Josef Kiermaier e Jörg Heilmann. "In Vitro Metabolism of Six C-Glycosidic Flavonoids from Passiflora incarnata L." International Journal of Molecular Sciences 22, n. 12 (18 giugno 2021): 6566. http://dx.doi.org/10.3390/ijms22126566.

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Abstract (sommario):

Several medical plants, such as Passiflora incarnata L., contain C-glycosylated flavonoids, which may contribute to their efficacy. Information regarding the bioavailability and metabolism of these compounds is essential, but not sufficiently available. Therefore, the metabolism of the C-glycosylated flavones orientin, isoorientin, schaftoside, isoschaftoside, vitexin, and isovitexin was investigated using the Caco-2 cell line as an in vitro intestinal and epithelial metabolism model. Isovitexin, orientin, and isoorientin showed broad ranges of phase I and II metabolites containing hydroxylated, methoxylated, and sulfated compounds, whereas schaftoside, isoschaftoside, and vitexin underwent poor metabolism. All metabolites were identified via UHPLC-MS or UHPLC-MS/MS using compound libraries containing all conceivable metabolites. Some structures were confirmed via UHPLC-MS experiments with reference compounds after a cleavage reaction using glucuronidase and sulfatase. Of particular interest is the observed cleavage of the C–C bonds between sugar and aglycone residues in isovitexin, orientin, and isoorientin, resulting in unexpected glucuronidated or sulfated luteolin and apigenin derivatives. These findings indicate that C-glycosidic flavones can be highly metabolized in the intestine. In particular, flavonoids with ortho-dihydroxy groups showed sulfated metabolites. The identified glucuronidated or sulfated aglycones demonstrate that enzymes expressed by Caco-2 cells are able to potentially cleave C–C bonds in vitro.

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48

GODDAT, J., A. A. GREY, M. HRICOVINI, J. GRUSHCOW, J. P. CARVER e R. N. SHAH. "ChemInform Abstract: Synthesis of Di- and Trisaccharides with Intramolecular NH-Glycosidic Linkages: Molecules with Flexible and Rigid Glycosidic Bonds for Conformational Studies." ChemInform 25, n. 23 (19 agosto 2010): no. http://dx.doi.org/10.1002/chin.199423221.

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49

NAKATANI, Hiroshi. "Monte Carlo simulation of hyaluronidase reaction involving hydrolysis, transglycosylation and condensation". Biochemical Journal 365, n. 3 (1 agosto 2002): 701–5. http://dx.doi.org/10.1042/bj20011769.

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Abstract (sommario):

The action of hyaluronidase on oligosaccharides from hyaluronan is complicated due to branched reaction paths containing hydrolysis, transglycosylation and condensation. The unit component of hyaluronan is a disaccharide, namely GlcA-(β1→3)-GlcNAc where GlcA and GlcNAc are d-glucuronic acid and d-N-acetylglucosamine respectively. Hyaluronan is the linear polymer formed by these disaccharide units, linked together with β1→4 glycosidic bonds. Bovine testicular hyaluronidase acts only at β1→4 glycosidic bonds of hyaluronan. The progress of product distribution from short oligosaccharides was simulated with the Monte Carlo method using the probabilistic model. The model consists only of a single enzyme molecule and a finite number of substrate and water molecules. The simulation is based on a simple reaction scheme and proceeds via an algorithm with minimum adjustable parameters generating random numbers and probabilities. The experimental data for bovine testicular hyaluronidase using [GlcA-(β1→3)-GlcNAc]4 as the starting substrate were quantitatively simulated with only three adjustable parameters. The simulated data for [GlcA-(β1→3)-GlcNAc]3 and [GlcA-(β1→3)-GlcNAc]5 as the starting substrates agreed semi-quantitatively with experimental data using the same parameters. The mechanism of the hyaluronidase reaction is a combination of branched probabilistic cycles. The condensation reaction is much weaker than the transglycosylation reaction but contributes to product distribution at the final stage of the reaction, preventing complete hydrolysis of the substrates.

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Franceus, Jorick, e Tom Desmet. "A GH13 glycoside phosphorylase with unknown substrate specificity from Corallococcus coralloides". Amylase 3, n. 1 (1 gennaio 2019): 32–40. http://dx.doi.org/10.1515/amylase-2019-0003.

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Abstract (sommario):

Abstract Glycoside phosphorylases in subfamily GH13_18 of the carbohydrate-active enzyme database CAZy catalyse the reversible phosphorolysis of α-glycosidic bonds. They contribute to a more energy-efficient metabolism in vivo, and can be applied for the synthesis of valuable glucosides, sugars or sugar phosphates in vitro. Continuing our efforts to uncover new phosphorylase specificities, we identified an enzyme from the myxobacterium Corallococcus coralloides DSM 2259 that does not feature the signature sequence patterns of previously characterised phosphorylases. The enzyme was recombinantly expressed and subjected to substrate screening. Although it was confirmed that the Corallococcus phosphorylase does not have the same substrate specificity as other phoshorylases from subfamily GH13_18, its true natural substrate remains a mystery for now. Myxobacteria have been widely investigated as producers of numerous bioactive secondary metabolites for decades, but little research has been conducted on myxobacterial proteins. The present study exemplifies the untapped metabolic activities and functional diversity that these fascinating organisms may have left to show.

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