Apyrimidinic Sites In DNA Research Articles

On the use of model compounds to assess 2-deoxy-D-erythro-pentofuranose conformation at apyrimidinic sites in DNA

On the use of model compounds to assess 2-deoxy-D-erythro-pentofuranose conformation at apyrimidinic sites in DNA

4863847 Process for directly determining apurinic and apyrimidinic sites in DNA: Myria Talpaert-Borle, Miche Liuzzi, Ispra, Italy assigned to Europaische Atomgemeinschaft

4863847 Process for directly determining apurinic and apyrimidinic sites in DNA: Myria Talpaert-Borle, Miche Liuzzi, Ispra, Italy assigned to Europaische Atomgemeinschaft

4863847 Process for directly determining apurinic and apyrimidinic sites in DNA: Myria Talpaert-Borle, Miche Liuzzi, Ispra, Italy assigned to Europaische Atomgemeinschaft

4863847 Process for directly determining apurinic and apyrimidinic sites in DNA: Myria Talpaert-Borle, Miche Liuzzi, Ispra, Italy assigned to Europaische Atomgemeinschaft

Mechanism of DNA strand nicking at apurinic/apyrimidinic sites by Escherichia coli [formamidopyrimidine]DNA glycosylase.

Escherichia coli [formamidopyrimidine]DNA glycosylase catalyses the nicking of both the phosphodiester bonds 3' and 5' of apurinic or apyrimidinic sites in DNA so that the base-free deoxyribose is replaced by a gap limited by 3'-phosphate and 5'-phosphate ends. The two nickings are not the results of hydrolytic processes; the [formamidopyrimidine]DNA glycosylase rather catalyses a beta-elimination reaction that is immediately followed by a delta-elimination. The enzyme is without action on a 3'-terminal base-free deoxyribose or on a 3'-terminal base-free unsaturated sugar produced by a beta-elimination reaction nicking the DNA strand 3' to an apurinic or apyrimidinic site.

Hydroxymethyluracil DNA glycosylase in mammalian cells.

An activity has been purified 350-fold from extracts of mouse plasmacytoma cells that forms 5-hydroxymethyluracil (alpha-hydroxythymine) and apyrimidinic sites with phage SPO1 DNA, which contains this base in place of thymine. This DNA glycosylase presumably functions to eliminate hydroxymethyluracil, a major thymine-derived DNA lesion produced by ionizing radiation and oxidative damage. The enzyme has no cofactor requirement and is active in EDTA. Neither intermediate formation nor hydrolysis of hydroxymethyl-deoxyuridine or hydroxymethyldeoxyuridine monophosphate was detected. The enzyme does not cleave apyrimidinic sites in DNA. It does release uracil from the uracil-containing DNA of phage PBS2, but this activity is less than 2% of the predominant uracil DNA glycosylase activity of the cell, which is separated by phosphocellulose chromatography. The major uracil DNA glycosylase does not release hydroxymethyluracil from SPO1 DNA. The hydroxymethyluracil glycosylase is also separated upon phosphocelluose chromatography from a thymine glycol DNA glycosylase activity that is accompanied by an apyrimidinic endonuclease activity.

A new endonuclease from Escherichia coli acting at apurinic sites in DNA.

A new DNA endonuclease has been purified 3000-fold from Escherichia coli. The enzyme specifically catalyzes the formation of single strand breaks at apurinic and apyrimidinic sites in DNA, but has no activity on intact or single-stranded DNA. Further, the enzyme shows little or no activity on heavily ultraviolet-irradiated DNA, but cleaves x-irradiated DNA, presumably at apurinic and apyrimidinic sites introduced by the radiation treatment. The enzyme, which is tentatively named endonuclease IV, has no detectable associated exonuclease or DNA N-glycosidase activity and does not seem to be identical with any previously known E. coli endonuclease. Endonuclease IV has no Mg2+ requirement, and is fully active in the presence of EDTA. Enzyme activity is stimulated by 0.2 to 0.3 M NaCl and is unusually salt-resistant. Further, the enzyme is fairly heat-stable, and is not inhibited by tRNA. The sidimentation coefficient, S(o)20,w, is 3.4 S. It seems that endonuclease IV is active in DNA repair.

Human endonuclease specific for apurinic/apyrimidinic sites in DNA. Partial purification and characterization of multiple forms from placenta.

Six chromatographically distinct forms of endonuclease active on apurinic and apyrimidinic sites in DNA have been purified away from DNA phosphatases, DNA N-glycosidases, and other DNases of human placenta. The forms seem to be monomeric proteins of 27,000 to 31,000 daltons, and although catalytically similar, they can be distinguished from one another on the basis of substrate Km and the effects of small molecules such as ATP. Analysis of enzymatic activity on a spectrum of damaged DNA substrates indicates that the enzyme forms probably act at an appreciable rate only adjacent to the phosphodiester bond of a deoxyribose lacking a base (purine or pyrimidine) in duplex DNA; such sites can be formed by treating the DNA with acid, alkylating agents, DNA N-glycosidases, and, probably, x-rays and OsO4. The incision is made so as to form a deoxyribose 5'-phosphate and a 3'-hydroxynucleotide.