Carbohydrates possess a variety of distinct features with stereochemistry playing a particularly important role in distinguishing their structure and function. Monosaccharide building blocks are ...defined by a high density of chiral centers. Additionally, the anomericity and regiochemistry of the glycosidic linkages carry important biological information. Any carbohydrate-sequencing method needs to be precise in determining all aspects of this stereodiversity. Recently, several advances have been made in developing fast and precise analytical techniques that have the potential to address the stereochemical complexity of carbohydrates. This perspective seeks to provide an overview of some of these emerging techniques, focusing on those that are based on NMR and MS-hybridized technologies including ion mobility spectrometry and IR spectroscopy.
Bismuth(V)-Mediated Thioglycoside Activation Goswami, Manibarsha; Ellern, Arkady; Pohl, Nicola L. B.
Angewandte Chemie (International ed.),
August 5, 2013, Letnik:
52, Številka:
32
Journal Article
Recenzirano
A straightforward method utilizing a bismuth(V) compound was developed for the activation of thiopropylglycosides for coupling to various acceptors; good to excellent yields were obtained without ...applying additional additives/co‐promoters. The method does not require low temperatures, is applicable to a wide variety of carbohydrates, and tolerates different functional groups including alkenes.
Carbohydrate purification remains a bottleneck in securing analytical standards from natural sources or by chemical or enzymatic synthesis. This review highlights the scope and remaining limitations ...of recent approaches and methods development in liquid chromatography for robust and higher-throughput carbohydrate separation and isolation.
This review highlights current techniques for carbohydrate purification and identifies research gaps.
De novo carbohydrate sequencing, including monosaccharide identification, largely remains a tremendous analytical challenge. A first step in the complete structural determination of any large ...polysaccharide is an accurate and robust method for analysis of the constituent monosaccharides. Herein, the first mass spectrometry-based method for the complete identification and absolute configuration determination of all 12 pentose isomers, including the d and l enantiomers for arabinose, lyxose, ribose, xylose, ribulose, and xylulose, is reported. As compared to earlier work to distinguish hexose isomers, the chiral separation of the pentose isomers was significantly more challenging. Specifically, the 12 pentoses are much more structurally similar to one another, with only the axial or equatorial orientation of two hydroxyl groups differentiating among these isomers in their five-membered ring furanose structure and smaller energetic differences between pentose conformations than between hexose conformations. Despite such inherently minimal energetic differences between the 12 pentoses, two unique fixed ligand kinetic method combinations were discovered to achieve chiral discrimination for this set of isomers. This assay can be readily applied to the identification of any isolated pentose monosaccharide using only microgram quantities and a commercial instrument and complements the method to distinguish hexose isomers. A workflow that incorporates this mass spectrometry-based method and thereby could achieve complete de novo identification of all monosaccharide building blocks in an oligo- or polysaccharide is proposed.
The first block iteration strategy for iterative solution-phase synthesis of protected keratan sulfate (KS)-like fragments is reported. Obstacles in a strategy using galactose-glucosamine ...(Gal-GlcNAc) modules led to the discovery of a differentially protected GlcNAc-Gal module that could be used to synthesize KS-like fragments using a fluorous tag that maintained solubility in organic solvents for purification of all intermediates via fluorous solid-phase extraction.
The first automated solution-phase synthesis of β-1,4-mannuronate and β-1,4-mannan oligomers has been accomplished by using a β-directing C-5 carboxylate strategy. By utilizing fluorous-tag assisting ...purification after repeated reaction cycles, β-1,4-mannuronate was synthesized up to a hexasaccharide with limited loading of a glycosyl donor (up to 3.5 equiv) for each glycosylation cycle due to the homogeneous solution-phase reaction condition. After a global reduction of the uronates, the β-1,4-mannan hexasaccharide was obtained, thereby demonstrating a new approach to β-mannan synthesis.
Rapid development of antisense therapies can enable on-demand responses to new viral pathogens and make personalized medicine for genetic diseases practical. Antisense phosphorodiamidate morpholino ...oligomers (PMOs) are promising candidates to fill such a role, but their challenging synthesis limits their widespread application. To rapidly prototype potential PMO drug candidates, we report a fully automated flow-based oligonucleotide synthesizer. Our optimized synthesis platform reduces coupling times by up to 22-fold compared to previously reported methods. We demonstrate the power of our automated technology with the synthesis of milligram quantities of three candidate therapeutic PMO sequences for an unserved class of Duchenne muscular dystrophy (DMD). To further test our platform, we synthesize a PMO that targets the genomic mRNA of SARS-CoV-2 and demonstrate its antiviral effects. This platform could find broad application not only in designing new SARS-CoV-2 and DMD antisense therapeutics, but also for rapid development of PMO candidates to treat new and emerging diseases.
A one-step protocol for the automated flow synthesis of protected glycosylated amino acids is described using pumps with open-source controls in overall yields of 21-50%. The resulting glycosylated ...amino acids could be used directly in solid-phase peptide synthesis (SPPS) protocols to quickly produce glycopeptide standards. Access to a variety of stereoisomers of the sugar enabled the development of an LC-MS/MS protocol that can distinguish between peptides modified with carbohydrates having the same exact mass. This method could definitively identify fucose in an
O
-glycosylation site on the transmembrane protein, Notch1.
A one-step automated flow protocol for the synthesis of protected glycosylated amino acids enabled the production of glycopeptide standards that were used towards the development of an LC-MS/MS protocol.
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