scholarly journals Regioselective Silyl/Acetate Exchange of Disaccharides Yields Advanced Glycosyl Donor and Acceptor Precursors

2013 ◽  
Vol 78 (19) ◽  
pp. 9677-9688 ◽  
Author(s):  
Hsiao-Wu Hsieh ◽  
Matthew W. Schombs ◽  
Mark A. Witschi ◽  
Jacquelyn Gervay-Hague
Keyword(s):  
Donor And Acceptor ◽  
Glycosyl Donor

scholarly journals Structures of cell wall arabinosyltransferases with the anti-tuberculosis drug ethambutol

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. 1211-1219 ◽  
Author(s):  
Lu Zhang ◽  
Yao Zhao ◽  
Yan Gao ◽  
Lijie Wu ◽  
Ruogu Gao ◽  
...  
Keyword(s):  
Cell Wall ◽  
Active Site ◽  
Structural Basis ◽  
Drug Resistant ◽  
Cell Wall Synthesis ◽  
X Ray ◽  
Cryo Electron Microscopy ◽  
Donor And Acceptor ◽  
Biochemical Function ◽  
Glycosyl Donor

The arabinosyltransferases EmbA, EmbB, and EmbC are involved in Mycobacterium tuberculosis cell wall synthesis and are recognized as targets for the anti-tuberculosis drug ethambutol. In this study, we determined cryo–electron microscopy and x-ray crystal structures of mycobacterial EmbA-EmbB and EmbC-EmbC complexes in the presence of their glycosyl donor and acceptor substrates and with ethambutol. These structures show how the donor and acceptor substrates bind in the active site and how ethambutol inhibits arabinosyltransferases by binding to the same site as both substrates in EmbB and EmbC. Most drug-resistant mutations are located near the ethambutol binding site. Collectively, our work provides a structural basis for understanding the biochemical function and inhibition of arabinosyltransferases and the development of new anti-tuberculosis agents.

Chemo-enzymatic synthesis of Lacto-N-biose I catalyzed by β-1,3 galactosidase from Bacillus circulans using 4,6-dimethoxy-1,3,5-triazin-2-yl β-galactopyranoside as a glycosyl donor

2021 ◽  
Author(s):  
Takayuki Ohnuma ◽  
Tomoki Taku ◽  
Takeshi Nagatani ◽  
Atsushi Horii ◽  
Shun Imaoka ◽  
...  
Keyword(s):  
Enzymatic Synthesis ◽  
Maximum Yield ◽  
Bacillus Circulans ◽  
Donor Substrate ◽  
Donor And Acceptor ◽  
Glycosyl Donor ◽  
Substrate Ratio

Abstract Chemo-enzymatic synthesis of lacto-N-biose I (LNB) catalyzed by β-1,3 galactosidase from Bacillus circulans (BgaC) has been developed using 4,6-dimethoxy-1,3,5-triazin-2-yl β-galactopyranoside [DMT-β-Gal] and GlcNAc as the donor and acceptor substrates, respectively. BgaC transferred the Gal moiety to the acceptor, giving rise to LNB. The maximum yield of LNB was obtained at the acceptor: donor substrate ratio of 1:30.

Synthesis of a New Type ofd-Mannosamine Glycosyl Donor and Acceptor and their Use for the Preparation of Oligosaccharides Consisting ofd-Mannosamine Units Linked by α(1→4)-Glycosidic Bonds

Synthesis ◽  
2008 ◽  
Vol 2008 (16) ◽  
pp. 2610-2616 ◽  
Author(s):  
Miroslav Ledvina ◽  
Matyáš Turský ◽  
Jan Veselý ◽  
Iva Tišlerová ◽  
Tomáš Trnka
Keyword(s):  
Glycosidic Bonds ◽  
Donor And Acceptor ◽  
New Type ◽  
Glycosyl Donor

scholarly journals Intramolecular glycosylation

2017 ◽  
Vol 13 ◽  
pp. 2028-2048 ◽  
Author(s):  
Xiao G Jia ◽  
Alexei V Demchenko
Keyword(s):  
Review Article ◽  
Donor And Acceptor ◽  
Leaving Group ◽  
Glycosyl Donor

Carbohydrate oligomers remain challenging targets for chemists due to the requirement for elaborate protecting and leaving group manipulations, functionalization, tedious purification, and sophisticated characterization. Achieving high stereocontrol in glycosylation reactions is arguably the major hurdle that chemists experience. This review article overviews methods for intramolecular glycosylation reactions wherein the facial stereoselectivity is achieved by tethering of the glycosyl donor and acceptor counterparts.

scholarly journals Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

2017 ◽  
Vol 13 ◽  
pp. 2094-2114 ◽  
Author(s):  
Weizhun Yang ◽  
Bo Yang ◽  
Sherif Ramadan ◽  
Xuefei Huang
Keyword(s):  
Building Blocks ◽  
Sialic Acids ◽  
Uronic Acids ◽  
Protective Group ◽  
One Pot ◽  
Donor And Acceptor ◽  
Glycosyl Donor ◽  
Complex Glycans ◽  
Powerful Strategy ◽  
Multiple Step

Most glycosylation reactions are performed by mixing the glycosyl donor and acceptor together followed by the addition of a promoter. While many oligosaccharides have been synthesized successfully using this premixed strategy, extensive protective group manipulation and aglycon adjustment often need to be performed on oligosaccharide intermediates, which lower the overall synthetic efficiency. Preactivation-based glycosylation refers to strategies where the glycosyl donor is activated by a promoter in the absence of an acceptor. The subsequent acceptor addition then leads to the formation of the glycoside product. As donor activation and glycosylation are carried out in two distinct steps, unique chemoselectivities can be obtained. Successful glycosylation can be performed independent of anomeric reactivities of the building blocks. In addition, one-pot protocols have been developed that have enabled multiple-step glycosylations in the same reaction flask without the need for intermediate purification. Complex glycans containing both 1,2-cis and 1,2-trans linkages, branched oligosaccharides, uronic acids, sialic acids, modifications such as sulfate esters and deoxy glycosides have been successfully synthesized. The preactivation-based chemoselective glycosylation is a powerful strategy for oligosaccharide assembly complementing the more traditional premixed method.

scholarly journals Hydrogen Bond Synchronized Dual Activation Enables the Unified β-Selective O-Glycosylation Inside a Molecular Capsule

2021 ◽  
Author(s):  
Tian-Ren Li ◽  
Fabian Huck ◽  
GiovanniMaria Piccini ◽  
Konrad Tiefenbacher
Keyword(s):  
High Selectivity ◽  
Confined Space ◽  
Central Importance ◽  
Substitution Pattern ◽  
Donor And Acceptor ◽  
Molecular Capsule ◽  
Glycosyl Donor ◽  
Dual Activation ◽  
Selective Formation ◽  
Very High

<div>Carbohydrates are of central importance in biology. The selective chemical synthesis of carbohydrates, however, still poses a challenge; particularly, the selective formation of the</div><div>thermodynamically labile b-glycosidic bond is difficult and depends on the substrate’s substitution pattern. We here demonstrate that a molecular capsule catalyzes the highly</div><div>challenging selective formation of b-glycosides independent of the substrate’s substitution pattern and configuration. We demonstrate the versatility of the catalyst by synthesizing small to medium sized 1,2-cis, 2-deoxy, and 1,2-trans b-glycosides in very high selectivity and good yield. The confined space inside the molecular capsule naturally limits the scope concerning the size of reactants. Interestingly, the proposed mechanism involves the synchronized activation of the glycosyl donor and acceptor inside the supramolecular capsule via a relay involving seven hydrogen bonds. Such an activation is known for enzymes, however, to our knowledge, is unprecedented for man-made catalysts.</div>

ChemInform Abstract: Regioselective Silyl/Acetate Exchange of Disaccharides Yields Advanced Glycosyl Donor and Acceptor Precursors.

ChemInform ◽  
2014 ◽  
Vol 45 (10) ◽  
pp. no-no
Author(s):  
Hsiao-Wu Hsieh ◽  
Matthew W. Schombs ◽  
Mark A. Witschi ◽  
Jacquelyn Gervay-Hague
Keyword(s):  
Donor And Acceptor ◽  
Glycosyl Donor
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