Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

A library of Bacillus subtilis chromosomal deoxyribonucleic acid (DNA) was constructed, using lambda charon 4A as a cloning vector. Partially cleaved Bacillus subtilis DNA was prepared by partial methylation with EcoRI methylase, followed by complete EcoRI endonuclease digestion. More than 95% of the phage particles carried B. subtilis DNA inserts. When this library was screened for transforming activity, using competent cells, 70% of the genetic markers tested were found in a sample of 1,710 plaques. Cloned genetic loci were found to be about 100-fold more efficient in transforming activity than chromosomal DNA. Intact phage particles containing the pheA locus were found to be able to transform competent recipients with approximately the same efficiency as phage DNA. Transformation by intact particles was insensitive to deoxyribonuclease.
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PMID:Isolation of Bacillus subtilis genes from a charon 4A library. 626 Jul 47

Preparations of purified Rauscher murine leukemia virus were found to contain an endodeoxyribonuclease after disruption of the virus with nonionic detergents. The enzyme makes single-strand breaks in linear or covalently closed circular phage double-stranded DNA molecules. The enzyme was partially purified by ion-exchange chromatography on DEAE- and carboxymethyl-Sepharose columns followed by electrophoresis in DNA-containing polyacrylamide gels. The enzyme was separated from reverse transcriptase (p80pol), and the final endonuclease preparation contained no detectable reverse transcriptase activity. The DEAE-Sepharose column-purified endonuclease activity contained a polypeptide of about 40,000 Mr that we term p40. Peptide mapping experiments demonstrated that p40 shares methionine-labeled tryptic peptides with Pr200gag-pol and Pr135pol. Six major methionine-labeled tryptic peptides derived from p40 were found in Pr200gag-pol, but only five of these were detected in Pr135pol. The four core proteins (p30, p15, pp12, and p10) and p80pol plus p40 account for most, but not all, of the peptide sequences of Pr200gag-pol. The endonuclease-associated p40 is similar in size and precursor origin to the avian retrovirus-coded endonuclease (p32). In view of these similarities to the avian p32 endonuclease and its association with partially purified Rauscher murine leukemia virus-associated endonuclease preparations, we propose that p40 is the Rauscher murine leukemia virus-coded endonuclease.
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PMID:Endodeoxyribonuclease activity associated with Rauscher murine leukemia virus. 626 Sep 82

The ATP-dependent deoxyribonuclease from Bacillus laterosporus has been purified to near homogeneity by a procedure involving ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephadex G-150 gel filtration, DEAE-Sephadex A-25 chromatography and DNA-cellulose affinity chromatography. The purified enzyme has a molecular weight of 210,000 +/- 8,000 as determined by sucrose gradient sedimentation. It is composed of two nonidentical polypeptide chains with close molecular weights of around 110,000. The substrate preference of the pure enzyme is essentially identical with the previous result obtained with the partially purified enzyme preparation (Anai, M., Mihara, T., Yamanaka, M., Shibata, T., & Takagi, Y. (1975) J. Biochem. 78, 105-114). Thus, the enzyme degrades double-stranded DNA about 100 times faster than heat-denatured DNA in the presence of ATP. Double-stranded DNA is not degraded to any measurable extent in the absence of ATP, but the enzyme exhibits activity toward denatured DNA in the absence of ATP. Furthermore, no endonuclease activity is observed on covalently closed circular duplex DNA and open circular duplex DNA.
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PMID:An adenosine triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. Improved purification, subunit structure and substrate specificity. 626 32

T4 endonuclease V [endodeoxyribonuclease (pyrimidine dimer), EC 3.1.25.1)], which is involved in repair of UV-damaged DNA, has been purified to apparent physical homogeneity. Incubation of UV-irradiated poly(dA).poly(dT) with the purified enzyme preparations resulted in production of alkali-labile apyrimidinic sites, followed by formation of nicks in the polymer. The activity to produce alkali-labile sites was optimal in a relatively broad pH range (pH 6.0-8.5), whereas the activity to form nicks had a narrow optimum near pH 6.5. By performing a limited reaction with T4 endonuclease V at pH 8.5, irradiated polymer was converted to an intermediate form that carried a large number of alkali-labile sites but only a few nicks. The intermediate was used as substrate for the assay of apurinic/apyrimidinic DNA endonuclease activity [endodeoxyribonuclease (apurinic or apyrimidinic, EC 2.1.25.2]. The two activities, a pyrimidine dimer DNA glycosylase and an apurinic/apyrimidinic DNA endonuclease, were copurified and found in enzyme preparations that contained only a 16,000-dalton polypeptide. An enzyme fraction from cells infected with bacteriophage T4v1, a mutant that is sensitive to UV radiation, was defective in both glycosylase and endonuclease activities. Moreover, occurrence of an amber mutation in the denV gene caused a simultaneous loss of the two activities, and suppression of the mutation rendered both activities partially active. These results strongly suggested that a DNA glycosylase specific for pyrimidine dimers and an apurinic/apyrimidinic DNA endonuclease reside in a single polypeptide chain coded by the denV gene of bacteriophage T4. Because the two activities exhibited different thermosensitivity, it was further suggested that conformation of the active sites for these activities may be different.
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PMID:Physical association of pyrimidine dimer DNA glycosylase and apurinic/apyrimidinic DNA endonuclease essential for repair of ultraviolet-damaged DNA. 626 6

Endonuclease V from E. coli infected with phage T4 was used to evaluate the frequency and the removal of pyrimidine dimers from DNA in cultured mammalian cells. Cellular membranes were made permeable to the enzyme by two cycles of rapid freezing and thawing. The number of endonuclease-sensitive sites in DNA was assayed by sedimentation in alkaline sucrose gradients upon which the cells were lysed directly. Comparison of the frequency of endonuclease-sensitive sites with the frequency of pyrimidine dimers determined by chromatographic analysis of hydrolysed DNA indicated that about 50% of the dimers in the permeabilized cells were substrates for T4 endonuclease V. This was confirmed by observation that when DNA treated with the enzyme in situ was purified, it contained the expected additional number of endonuclease-sensitive sites if again treated with the enzyme. The percentage of pyrimidine dimers recognized by T4 endonuclease V was enhanced to nearly 100% by exposing the permeabilized cells to 2 M NaCl before the enzyme was introduced. This method allowed the measurement of frequencies of endonuclease-sensitive sites after doses of UV irradiation at low as 0.5 J/m2. Loss of endonuclease sites from cellular DNA was observed during post-irradiation incubation of V79 Chinese hamster cells and several human cell strains. A comparison of the results obtained in human cells with or without the high-salt exposure before endonuclease treatment suggested that the dimers recognized under low-salt conditions may be removed slightly faster than those recognized only after high-salt exposure.
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PMID:Sensitive determination of pyrimidine dimers in DNA of UV-irradiated mammalian cells. Introduction of T4 endonuclease V into frozen and thawed cells. 626 56

The major apurinic/apyrimidinic (AP) endodeoxyribonuclease from rat liver chromatin, an enzyme specific for AP sites in DNA, cleaves the phosphodiester bridge which is the immediate neighbour of the AP site on its 5' side leaving 3'-hydroxyl and 5'-phosphate ends. In contrast with Escherichia coli endonuclease VI, this chromatin enzyme is inactive on reduced AP sites.
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PMID:Localization of the phosphoester bond hydrolyzed by the major apurinic/apyrmidinic endodeoxyribonuclease from rat-liver chromatin. 626 47

An apurinic endonuclease activity has been characterized in yeast mitochondrial. It is dependent on Mg2+, stimulated by about 50% in the presence of 50 mM NaCl and inhibited at higher NaCl concentrations. It is located in the inner mitochondrial membrane and requires high concentrations of detergent (1.5-3% Triton X-100) to be extracted. The same treatment extracts several other endonuclease activities: the two Mg2+-dependent endonuclease activities cleaving double-stranded DNA at pH 7.5 and 5.4 respectively, the ethidium-bromide-stimulated endonuclease activity, the endonuclease activity cleaving single-stranded DNA at pH 7.l5 [Jacquemin-Sablon et al. (1979) Biochemistry, 18, 119-127], and a manganese-stimulated deoxyribonuclease activity cleaving double-stranded DNA at pH 7.5 which has been discovered during the present work. Another endonuclease activity cleaving double-stranded DNA at pH 7.5 in the presence of Mg2+, slightly stimulated by low NaCl concentrations and inhibited by ethidium bromide is extracted from the membrane pellet remaining after the treatment with 1.5% Triton X-100 by a second treatment with 1.5% Triton X-100 plus 1 M KCl. The presence in the mitochondrial membrane of this apurinic endonuclease activity indicates that, like nuclear and prokaryotic DNA, yeast mitochondrial DNA is also subject to specialized repair systems.
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PMID:Endonucleases in yeast mitochondria: apurinic and manganese-stimulated deoxyribonuclease activities in the inner mitochondrial membrane of Saccharomyces cerevisiae. 628 1

We have examined the kinetics of the interaction between endodeoxyribonuclease EcoRI (EC 3.1.23.13) and nine linear DNA fragments that range in size between 34 and 6,200 base pairs and contain the EcoRI site of plasmid pBR322 in a central location. The kinetic parameters governing both formation and decay of specific endonuclease . DNA complexes increase 8-fold with increasing chain length over this size range. In contrast, equilibrium competition experiments demonstrated that the intrinsic affinity of endonuclease for its recognition sequence is independent of DNA chain length over this range. Thus, DNA sequences outside the recognition site enhance the rate at which EcoRI endonuclease locates or leaves its recognition site without affecting the intrinsic thermodynamic parameters of site-specific interaction. These results are consistent with a facilitated diffusion mechanism for specific DNA site location by this enzyme.
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PMID:Involvement of outside DNA sequences in the major kinetic path by which EcoRI endonuclease locates and leaves its recognition sequence. 628 60

Most of the activity of endodeoxyribonuclease was extracted from isolated chromatin with buffer containing 0.6 M NaCl, indicating that the endonuclease is present as a chromatin-bound form. When nuclei or chromatin of calf thymus or rat liver was digested with the bovine nuclear enzyme in the presence of 2 mM EGTA, to suppress endogenous Ca, Mg-dependent DNase activity, discrete DNA bands with integral multiples of 200 base pairs in length were produced, but no acid-soluble nucleotide was detected. The enzyme made single-strand breaks in pBR322 DNA and degraded it to fragments of limited size. The size of the final products of DNA's of Micrococcus luteus, rat liver nuclei, and calf thymus nuclei was about 3,000, 200, and 160 base pairs, respectively, but the enzyme showed no base specificity. Thus the endonuclease seems preferentially to recognize AT-rich regions of double-stranded DNA and to make single-strand breaks.
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PMID:Endodeoxyribonuclease from nuclei of bovine small intestinal mucosa: further studies on intranuclear localization and cleavage mechanism of the enzyme. 665 55

Escherichia coli endonuclease VI is a deoxyribonuclease specific for AP (apurinic or apyrimidinic) sites; it cleaves the phosphodiester bond immediately neighbouring the AP site on its 5' side leaving 3'-hydroxyl and 5'-phosphate ends. DNA with AP sites can be repaired in vitro with endonuclease VI, DNA polymerase I and ligase; the repair mechanism is described. E. coli has other AP endonucleases; some of them are not specific for AP sites and some of them cut 3' to the AP sites. Most of the rat liver AP endonuclease activity is in chromatin. Some is however found in other cell compartments and it has been speculated that these enzymes might be precursors of the chromatin enzyme. The chromatin AP endonuclease is specific for AP sites; it cuts 5' to the AP site. DNA with AP sites can be repaired in vitro with enzymes purified from chromatin; AP endonuclease, 5'-3 exonuclease, DNA polymerase beta and ligase.
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PMID:Repair of AP sites in DNA. 681 9


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