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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.
The different types of lipid-linked oligosaccharide (LLO) precursor produced in different organisms.. N-linked glycosylation is the attachment of an oligosaccharide, a carbohydrate consisting of several sugar molecules, sometimes also referred to as glycan, to a nitrogen atom (the amide nitrogen of an asparagine (Asn) residue of a protein), in a process called N-glycosylation, studied in ...
In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond. Glycosides can be linked by an O- (an O-glycoside), N- (a glycosylamine), S-(a thioglycoside), or C- (a C-glycoside) glycosidic bond.
The glycosidic bond is formed from a glycosyl donor and a glycosyl acceptor. There are four types of glycosidic linkages: 1, 2-trans-α, 1, 2-trans-beta, 1, 2-cis-α, and 1, 2-cis-beta linkages. 1, 2-trans glycosidic linkages can be easily achieved by using 2-O-acylated glycosyl donors (neighboring group participation).
They are also known as N-glycosides, [1] as they are a type of glycoside. Glycosyl groups can be derived from carbohydrates. The glycosyl group and amino group are connected with a β-N-glycosidic bond, forming a cyclic hemiaminal ether bond (α-aminoether). Examples include nucleosides such as adenosine.
To cleave the N-glycosidic bond, monofunctional glycosylases use an activated water molecule to attack carbon 1 of the substrate. Bifunctional glycosylases, instead, use an amine residue as a nucleophile to attack the same carbon, going through a Schiff base intermediate.
In organic chemistry, glycoside hydrolases can be used as synthetic catalysts to form glycosidic bonds through either reverse hydrolysis (kinetic approach) where the equilibrium position is reversed; or by transglycosylation (kinetic approach) whereby retaining glycoside hydrolases can catalyze the transfer of a glycosyl moiety from an ...
The side chain of Tyr147 interferes sterically with the thymine C5 methyl group, while a specific hydrogen bond between the uracil O2 carbonyl and Gln144 discriminates against a cytosine substrate, which lacks the necessary carbonyl. [9] Once uracil is recognized, cleavage of the glycosidic bond proceeds according to the mechanism below.