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These reactions are practically irreversible. Due to the fact that the cleavage of the N-glycosidic bond from the DNA backbone can lead to detrimental mutagenic and cytotoxic responses in an organism, have [clarify] the ability to also catalyze the synthesis of N-glycosidic bonds by way of an abasic DNA site and a specific nucleobase. [15]
DNA glycosylases catalyze the first step of this process. They remove the damaged nitrogenous base while leaving the sugar-phosphate backbone intact, creating an apurinic/apyrimidinic site, commonly referred to as an AP site. This is accomplished by flipping the damaged base out of the double helix followed by cleavage of the N-glycosidic bond. [1]
AP sites form when deoxyribose is cleaved from its nitrogenous base, breaking the glycosidic linkage between the two. This can happen spontaneously, as a result of chemical activity, radiation, or due to enzyme activity. The glycosidic linkages in DNA can be broken via acid-catalyzed hydrolysis. Purine bases can be ejected under weakly acidic ...
These are known as the 3′-end (three prime end), and 5′-end (five prime end) carbons, the prime symbol being used to distinguish these carbon atoms from those of the base to which the deoxyribose forms a glycosidic bond. [12] Therefore, any DNA strand normally has one end at which there is a phosphate group attached to the 5′ carbon of a ...
In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the nucleic acid assumes. The bases in the DNA are classified as purines and pyrimidines. The purines are adenine and guanine ...
Uracil DNA glycosylase flips a uracil residue out of the duplex, shown in yellow. DNA glycosylases are responsible for initial recognition of the lesion. They flip the damaged base out of the double helix, as pictured, and cleave the N-glycosidic bond of the damaged base, leaving an AP site. There are two categories of glycosylases ...
Uracil-DNA glycosylase (also known as UNG or UDG) is an enzyme. Its most important function is to prevent mutagenesis by eliminating uracil from DNA molecules by cleaving the N-glycosidic bond and initiating the base-excision repair (BER) pathway.
In a nucleoside, the anomeric carbon is linked through a glycosidic bond to the N9 of a purine or the N1 of a pyrimidine. Nucleotides are the molecular building blocks of DNA and RNA . List of nucleosides and corresponding nucleobases