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Glycosidic bonds of the form discussed above are known as O-glycosidic bonds, in reference to the glycosidic oxygen that links the glycoside to the aglycone or reducing end sugar. In analogy, one also considers S-glycosidic bonds (which form thioglycosides ), where the oxygen of the glycosidic bond is replaced with a sulfur atom.
Much of the chemistry of glycosides is explained in the article on glycosidic bonds. For example, the glycone and aglycone portions can be chemically separated by hydrolysis in the presence of acid and can be hydrolyzed by alkali. There are also numerous enzymes that can form and break glycosidic bonds.
A chemical glycosylation reaction involves the coupling of a glycosyl donor, to a glycosyl acceptor forming a glycoside. [1] [2] [3] If both the donor and acceptor are sugars, then the product is an oligosaccharide.
Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. It is one of the two components of starch , making up approximately 20–25% of it. Because of its tightly packed helical structure, amylose is more resistant to digestion than other starch molecules and is therefore an important ...
Typical cyclodextrins are constituted by 6-8 glucopyranoside units. These subunits are linked by 1,4 glycosidic bonds. The cyclodextrins have toroidal shapes, with the larger and the smaller openings of the toroid exposing to the solvent secondary and primary hydroxyl groups respectively. Because of this arrangement, the interior of the toroids ...
Amylopectin is synthesized by the linkage of α(1→4) Glycosidic bonds. The extensive branching of amylopectin (α(1→6) Glycosidic bond) is initiated by BE and this is what differentiates amylose from amylopectin. DBE is also needed during this synthesis process to regulate the distribution of these branches. [19] [22]
Starch is a glucose polymer in which glucopyranose units are bonded by alpha-linkages. It is made up of a mixture of amylose (15–20%) and amylopectin (80–85%). Amylose consists of a linear chain of several hundred glucose molecules, and Amylopectin is a branched molecule made of several thousand glucose units (every chain of 24–30 glucose ...
Alpha-glucan is also commonly found in bacteria, yeasts, plants, and insects. Whereas the main pathway of α-glucan synthesis is via glycosidic bonds of glucose monomers, α-glucan can be comparably synthesized via the maltosyl transferase GlgE and branching enzyme GlgB. [2] This alternative pathway is common in many bacteria, which use GlgB ...