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Human AP Endonuclease 2 (APE2), like most AP endonucleases, is also of class II. The exonuclease activity of APE2 is strongly dependent upon metal ions. However, APE2 was more than 5-fold more active in the presence of manganese than of magnesium ions. [4] The conserved domains involved in catalytic activity are located at the N-terminal part ...
The activity of AP endonuclease in the repair of AP sites in the frontal/parietal cortex, cerebellum, brain stem, midbrain and hypothalamus declines with age in rats on an ad libitum diet. [5] In calorie restricted rats, by comparison, AP endonuclease activity in these brain regions remains higher with age. [ 5 ]
Monofunctional glycosylases have only glycosylase activity, whereas bifunctional glycosylases also possess AP lyase activity that permits them to cut the phosphodiester bond of DNA, creating a single-strand break without the need for an AP endonuclease. β-Elimination of an AP site by a glycosylase-lyase yields a 3' α,β-unsaturated aldehyde ...
The mutated base gets removed through the base excision repair pathway, a two step mechanism carried out by a glycosylase and AP endonuclease. DNA deoxyinosine glycosylase initiates the process through hydrolytic cleavage of the hypoxanthine base, releasing a free hypoxanthine and creating an abasic, or AP site. AP endonuclease follows ...
AP sites are pre-mutagenic lesions that can prevent normal DNA replication. All cells, from simple prokaryotes to humans, have evolved systems to identify and repair such sites. Class II AP endonucleases cleave the phosphodiester backbone 5' to the AP site, thereby initiating a process known as base excision repair (BER).
AP endonucleases are divided into two families based on their homology to the ancestral bacterial AP endonucleases endonuclease IV and exonuclease III. [6] Many eukaryotes have members of both families, including the yeast Saccharomyces cerevisiae , in which Apn1 is the EndoIV homolog and Apn2 is related to ExoIII.
The AP endonuclease recognizes this sugar and essentially cuts the DNA at this site and then allows for DNA repair to continue. [10] E. coli cells contain two AP endonucleases: endonuclease IV (endoIV) and exonuclease III (exoIII) while in eukaryotes, there is only one AP endonuclease. [11]
AP site formation is a common occurrence in dsDNA. It is the result of spontaneous hydrolysis and the activity of DNA glycosylases as an intermediary step in base excision repair. These AP sites are removed by AP endonucleases, which effect single strand breaks around the site. [5]