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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 ...
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). The APEX gene (alternatively named APE1, HAP1, APEN) encodes the major AP endonuclease in human cells.
The enzyme DNA-(apurinic or apyrimidinic site) lyase, also referred to as DNA-(apurinic or apyrimidinic site) 5'-phosphomonoester-lyase (systematic name) or DNA AP lyase (EC 4.2.99.18) catalyzes the cleavage of the C-O-P bond 3' from the apurinic or apyrimidinic site in DNA via β-elimination reaction, leaving a 3'-terminal unsaturated sugar and a product with a terminal 5'-phosphate. [1]
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 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]
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]
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 ...
Depiction of the restriction enzyme (endonuclease) HindIII cleaving a double-stranded DNA molecule at a valid restriction site (5'–A|AGCTT–3').. In biochemistry, a nuclease (also archaically known as nucleodepolymerase or polynucleotidase) is an enzyme capable of cleaving the phosphodiester bonds that link nucleotides together to form nucleic acids.