Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

All Bacillus subtilis R-type strains showing the phenomena of restriction and modification contain an endonuclease that inactivates in vitro the biological activity of a variety of DNAs lacking R-specific modification, such as transfecting SPPI, SPO2 and phi105 DNA, and transforming B. subtilis 168-type DNA. The corresponding DNAs carrying R-specific modification are resistant to the enzyme. The enzyme has been purified approximately 400-fold and is essentially free from contaminating double strand-directed unspecific exo- or endonuclease activity. Only Mg2+ is required as cofactor. The substrate DNAs are cleaved at specific sites. The double-stranded fragments produced from SPP1 DNA (molecular weight 2.5 x 10(7)) have an average molecular weight of about 3 x 10(5).
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PMID:Restriction and modification in B. subtilis. Purification and general properties of a restriction endonuclease from strain R. 0 56

Two endonucleases, AvaI and AvaII, were isolated from Anabaena variabilis on the basis of their ability to make a limited number of breaks at specific points in bacteriophage lambda DNA. Neither enzyme has cofactor requirements beyond Mg2+. Endonuclease AvaI makes eight breaks in the phage lambda chromosome at which the 5'-terminal sequence is pPy-C-G-N. AvaII endonuclease cuts phage lambda DNA more extensively, yielding fragments with the 5'-terminal sequence G-T-C-N or G-A-C-N. Neither enzyme generates cohesive ends.
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PMID:Isolation and characterization of two sequence-specific endonucleases from Anabaena variabilis. 1 80

A restriction endonuclease was isolated from Bacillus stearothermophilus1503-4R (Bst1503) and purified to homogeneity. The enzyme required Mg2+ ion as a cofactor. Bst1503 exhibited maximal activity between pH 7.5 and 8.0, between 60 and 65 degrees C, and with about 0.2 mM Mg2+. Bst1503 was not inactivated after exposure at 55 or 65 degrees C for up to 10 h. After 2 h of incubation at 70 degrees C, Bst1503 was inactivated by 65%. Bst1503 was rapidly inactivated at 75 degrees C. A single protein-staining band having a molecular weight of 46,000 was observed when Bst1503 was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was found to exist in two active forms, the predominating form with an S value of 8.3 (180,000) and the second form with an S value of 5.4 (96,000). No conversion between the 8.3S and 5.4S forms was observed after storage. Bst1503 recognized six sites in TP-1C deoxyribonucleic acid (DNA), one site in pSC101 and simian virus 40 DNAs, and three sites in lambdavir DNA. Bst1503 and BamHI were determined to be isoschizomers. The effect of temperatures on the activity and stability of BamHI was determined.
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PMID:Isolation and properties of a thermostable restriction endonuclease (ENDO R-Bst1503). 1 5

Some physico-chemical properties, specificity and the character of action of rat liver nuclear ribonuclease are studied. The enzyme maximal activity was observed at pH 7.5--8.0, ionic strength 0.02--0.3, Mg2+ being necessary. Nuclease is an oligomer, having molecular weight is 160000--180000 daltons and containing separate associates. Purified enzyme is free of contaminating activities (polynucleotidephosphorylase, DNAse; 5'-nucleotidase, and alkaline phosphatases). It is shown to hydrolyse polyA and RNA for endonuclease type, degradation products being oligonucleotides terminating with 5'-phosphate and 3'-hydroxyl groups. RNAse hydrolyses all phosphodiester bonds in polynucleotides, developing no specificity to the nature of bases. Relative hydrolysis rate for different substrates decreased as follows: polyA greater than yeast RNA greater than polyC greater than polyU greater than 28S rRNA greater than greater than 18S rRNA greater than polyA-polyU. The enzyme may be classified as ribonucleate-5'-nucleotidehydrolase (EC 3.1.4.9.).
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PMID:[Nuclear ribonucleases and post-transcriptional changes of RNA. Specificity and other properties of rat liver nuclear endonuclease]. 1 31

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.
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PMID:A new endonuclease from Escherichia coli acting at apurinic sites in DNA. 1 2

An endonuclease which hydrolyzes depurinated DNA has been isolated from Phaseolus multiflorus enbryos; it has a molecular weight around 40,000. The enzyme is specific for apurinic sites; it has no action on normal DNA strands or on alkylated sites, and is without exonulcease activity. The rate of phosphoester bond hydrolysis near apurinic sites is far greater in native than in denatured DNA. The endonuclease is not inactivated by 10 mM EDTA, but is activity is however stimulated by Mg2+ or Mn2+. Its optimum pH is 7.5 to 8.0, and its optimum temperature 40degrees although, at this temperature, it is rapidly denatured; even low NaCl concentrations inhibit the enzyme activity. The endonuclease for apurinic sites of P. multiflorus is a non-histone protein of chromatin; the properties (like thermosensitivity of susceptibility to ionic strength) of the enzyme in situ, working on chromatin DNA, might be different from those described for the isolated endonuclease in homogenous aqueous solution.
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PMID:Purification and properties of a plant endonuclease specific for apurinic sites. 1 91

Acid ribonuclease, free of nucleases and phosphatases, is isolated from rat thymus chromatin. The pH optimum of the enzyme is 5.0-5.5, optimal concentrations of Na+ and K+ ions are 0.05-0.15 M and 0.05 M respectively, Mg2+ inhibits the enzyme activity. The enzyme hydrolyses poly U, poly AU, cytoplasmic and nuclear RNAs, but does not attack poly A, polyG, polyC, poly A:poly U, native and denatured DNA'S. The enzyme is 3'-endonuclease, it splits the bond between the 5'-carbon atom of adenosine, guanosine and uridine and 3'-phosphate of uridilic residue. Middle length of oligonucleotides after the hydrolysis of cytoplasmic RNA comprises 10 nucleotides. Possible role of the enzyme in the processing of nuclear RNAs is discussed.
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PMID:[Characteristics of acid ribonuclease from rat thymus chromatin]. 1 99

Evidence has been found on an alkaline endonuclease activity in the cytoplasmic and nuclear fraction isolated from the thymus and spleen mice. The chromatin-associated endonuclease activity was identified only in the spleen. The enzyme(s) was active on both single- and double-stranded DNA, but the reaction was faster if single-stranded DNA was used as a substrate. Maximum activity was found in the pH range of 7.9 to 8.1 in the presence of 10 mM Mg2+ and 1 mM Ca2+. The enzyme(s) splits DNA, yielding 3'-hydroxyl terminated polynucleotides. It is suggested that this alkaline endonuclease(s) is responsible for the formation of deoxyribopolynucleotides in the thymus and spleen of irradiated mice.
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PMID:Alkaline endonuclease(s) activity in the thymus and spleen of normal and irradiated mice. 2 4

The DNAase in human urine was purified about 30-fold with a recovery of 28%. This involved DEAE-cellulose and phosphocellulose chromatography steps and gel filtration on Sephadex G-75. The enzyme required divalent cations such as Co2+, Mg2+, Mn2+ and Zn2+ for activity, but Ca2+, Cu2+ and Fe2+ were ineffective. EDTA and G-actin inhibited the reaction. The maximum activity was observed at pH 5.5 in acetate buffer plus Co2+ or Mg2+ and Ca2+. It had a molecular weight of approximately 38 000, estimated by gel filtration on Sephadex G-75 and isoelectric point of around pH 3.9. The enzyme is an endonuclease which hydrolyzes native, double-stranded DNA about 3 to 4 times faster than thermally denatured DNA to produce 5'-phosphoryl- and 3'-hydroxyl-terminated oligonucleotides. The final preparation was free of non-specific acid and alkaline phosphatases, phosphodiesterase and ribonuclease activities.
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PMID:Purification and properties of deoxyribonuclease from human urine. 2 31

The endonuclease DNase II preferentially attacks a limited and tissue-specific portion of chromosomal DNA. This material may be separated from the bulk of chromatin DNA by virtue of its solubility in 2 mM MgCl2. The Mg2+ soluble fraction forms a specific subset of DNA sequences and is enriched four to sevenfold in sequences coding for cytoplasmic poly(A)-containing RNA and globin messenger RNA (in globin-producing cells). The bulk (70--90%) of rapidly labelled RNA is found associated with the Mg2+-soluble fraction. Transcriptionally active, Mc2+-soluble chromatin is organized into repeating subunits of DNA (200 +/- 5 base pairs) and histone. Mc2+-soluble active subunits differ from the subunits or nucleosomes of non-transcribed regions in many respects: namely, chemical composition (non-histone protein and RNA), sedimentation properties, differential sensitivity to DNase I and the single-strand-specific nuclease S1, and optical melting behaviour. These results suggest that chromatin subunits adopt a new configuration during the process of transcription.
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PMID:Organization of transcribed regions of chromatin. 2 80


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