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)

We have extensively purified from Krebs II ascites cells, although not until homogeneity, a ribonuclease which preferentially cleaves natural or synthetic double-stranded RNA substrates (RNase D); this specificity is also supported by its sensitivity to inhibition by 10(-5) M ethidium bromide. It does not degrade RNA-DNA hybrids and is, therefore, clearly distinct from previously characterized RNases H (Cathala, G., Rech, J., Huet, J., and Jeanteur, Ph. (1979) J. Biol. Chem. 254, 7354-7361). It shows no requirement for a divalent cation and is inhibited by all kinds of nucleic acids regardless of their secondary structure. It acts exclusively as an endonuclease, as shown by the analysis of degradation products, and yields 5'-phosphate termini. This enzyme is able to introduce discrete nicks into purified HeLa 45 S preribosomal RNA as well as into HeLa heterogenous nuclear RNA packaged within naturally occurring nuclear ribonucleoprotein particles. It is, therefore, an interesting candidate for an RNA-processing enzyme.
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PMID:Isolation and characterization of a ribonuclease activity specific for double-stranded RNA (RNase D) from Krebs II ascites cells. 624 30

Cyclobutyl pyrimidine dimers have been detected in the DNA of human skin following in vivo irradiation with suberythemal doses of ultraviolet (UV) radiation from FS-20 sun lamp fluorescent tubes. Dimers were assayed by treatment of extracted DNA with Micrococcus luteus UV-specific endonuclease, alkaline agarose electrophoresis, and ethidium bromide staining. This technique, in contrast to conventional dimer assays, can be used with nonradioactive DNA and is optimal at low UV light doses. M. luteus endonuclease-sensitive sites were determined after exposure of untanned skin in two volunteers to UV light (0.97, 1.94, or 3.88 X 10(3) J/sq m; lambda, 290 to 360 nm). At 20 min postirradiation (dose, 1.94 X 10(3) J/sq m), fewer M. luteus endonuclease-sensitive sites were found in the DNA than immediately after the irradiation. Even fewer endonuclease-sensitive sites were found at 20 min when the UV-irradiated skin was subsequently irradiated with visible light than when the area was kept in the dark. These data suggest that some dimer disappearance by excision repair occurs within 20 min of UV irradiation and that photoreactivation of dimers can make a contribution to the total repair process.
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PMID:Pyrimidine dimer formation and repair in human skin. 625 56

Bacteroides fragilis V479-1 has previously been shown to harbor a self-transmissible 27 X 10(6)-dalton plasmid (pBF4) which confers lincosamide-macrolide resistance. The present study has focused on the physical properties of pBF4. The plasmid was found to be present in 1 to 2 copies per chromosomal equivalent. pBF4 was genetically stable, although spontaneously occurring plasmidless segregants could be detected at low frequency (approximately 1%). This frequency was unaffected by growth of cells in ethidium bromide. About one-third of all spontaneously occurring macrolide-lincosamide-sensitive clones of strain V479-1 were found to contain pBF4 molecules that carried deletions. Ten independently obtained deletion derivatives of pBF4 from lincosamide-macrolide-sensitive strains were compared with the parental pBF4 by restriction endonuclease cleavage analysis. A restriction site map of pBF4 was constructed, and the location of the deletions was approximated. Self-annealed pBF4 molecules, examined by electron microscopy, revealed the presence of two pairs of inverted repeat (IR) sequences on the plasmid. IR-1 was about 400 base pairs in length, and its two component members were separated by an intervening sequence of about 15 kilobases. IR-2 was about 75 base pairs in length, and its component members were separated by 4.2 kilobases. Each of the deletions of pBF4 studied had a terminus at or near the same IR-2 sequence.
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PMID:Physical characterization of Bacteroides fragilis R plasmid pBF4. 625 54

An endodeoxyribonuclease has been purified from nuclei of bovine small intestinal mucosa to a homogeneous state by a procedure involving affinity chromatography on heparin-agarose. The endonuclease, which was found to be bound to chromatin, has a pH optimum of 5.4. It requires Mn2+ or Co2+ for activity and its maximum activity with Mg2+ is about 80% of that with Mn2+. Its activity is strongly inhibited by sulfhydryl-blocking agents, and by ethidium bromide. The enzyme does not attack RNA and is inhibited by it. Its isoelectric point is 8.5 +/- 0.1, and its molecular weight is 49,000 +/- 3,000, determined by sucrose gradient sedimentation and gel filtration on Sephadex G-100. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicated that the enzyme is composed of two nonidentical subunits with molecular weights of 30,000 and 23,000. The enzyme catalyzes the endonucleolytic cleavage of circular duplex ColE1 DNA via single strand scissions from the initial stage of degradation. The average size of the limit products of native phage T7 or ColE1 DNA is about 2,000 to 1,500 base pairs, estimated by neutral sucrose gradient sedimentation or agarose gel electrophoresis. The enzyme degrades denatured DNA about 20 times faster than native DNA. The products contain 5'-phosphoryl and 3'-hydroxyl termini, and all four deoxymononucleotides are present in almost equal amounts at the 5'-termini.
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PMID:Purification and properties of an endodeoxyribonuclease from nuclei of bovine small intestinal mucosa. 625 82

GCL3, a beta-lactamase-producing, penicillin resistant strain of Neisseria gonorrhoeae isolated in Toulouse (France), and GCL51, a penicillin susceptible strain, were examined for their plasmid content. Agarose-gel electrophoresis following or not ultracentrifugation in a cesium chloride-ethidium bromide gradients, revealed, for both strains a 3.9-kilobase (kb) (2.6 megadaltons) cryptic plasmid. Penicillin resistant strain GCL3 also contained a 37 kb (24.5 megadaltons) and a 7.3 kb (4.8 megadaltons) plasmid. Transformation studies showed that the gene responsible for beta-lactamase production was carried by the 7.3-kb plasmid. E. coli cells transformed for ampicillin resistance by plasmid DNA from GCL3, contained a single 7.3 kb-plasmid. The restriction endonuclease cleavage map obtained for this plasmid indicated that it is closely related to a penicillin R plasmid previously described in a strain isolated in the USA. The first isolation in the Midi-Pyrenees area of a beta-lactamase-producing strain proved the necessity of a rigorous surveillance of N. gonorrhoeae strains isolated in the world.
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PMID:[Isolation and characterization of a beta-lactamase-specifying plasmid in a strain of "neisseria gonorrhoeae" (author's transl)]. 627 Oct 37

Simple and practical methods for grouping of adenoviruses and for identification of restriction endonuclease cleavage patterns of viral DNA were established by using infected cell DNA. DNA homology groupings of adenoviruses could be examined by spot hybridization, and restriction endonuclease cleavage patterns of viral DNAs could be obtained by Southern blot hybridization, by using infected cell DNA. The method was very sensitive and allowed the identification of the cleavage pattern of viral DNA of the inoculum by means of cell DNA extracted from infected cells with undetectable cytopathic effect (CPE). In ethidium bromide-stained gels without Southern blot hybridization, the restriction endonuclease cleavage pattern of viral DNA could be detected precisely in spite of background staining due to cellular DNA. The preparation of infected cell DNA used in these procedures was technically much easier than that of viral DNA. These methods require only a small number of infected cells and allow many isolates to be investigated with ease.
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PMID:Grouping of adenoviruses and identification of restriction endonuclease cleavage patterns of adenovirus DNAs using infected cell DNA: simple and practical methods. 627 71

The reactions of the EcoRI restriction endonuclease on the covalently closed DNA of plasmid pMB9 were studied in the presence of ethidium bromide. At the concentrations of ethidium bromide tested, which covered the range over which the DNA is changed from negatively to positively supercoiled, the dye caused no alteration to the rate at which this enzyme cleaved the covalently closed DNA to yield the open-circle form, but the rate at which these open circles were cleaved to the linear product could be inhibited. The fluorescence change, caused by ethidium bromide binding with different stoichiometries to covalently closed and open-circle DNA, provided a direct and sensitive signal for monitoring the cleavage of DNA by this enzyme. This method was used for a steady-state kinetic analysis of the reaction catalysed by the EcoRI restriction enzyme. Reaction mechanisms where a complex between DNA and Mg2+ is the substrate for this enzyme were eliminated, and instead DNA and Mg2+ must bind to the enzyme in separate stages. The requisite controls for this fluorimetric assay in both steady-state and transient kinetics studies, and its application to other enzymes that alter the structure of covalently closed DNA, are described.
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PMID:The EcoRI restriction endonuclease, covalently closed DNA and ethidium bromide. 628 Jun 76

Human papilloma virus (HPV) was isolated from red plaques of a patient (N. F.) with epidermodysplasia verruciformis. Electron microscopic examination showed characteristic particles of papilloma virus as icosahedrons about 45 nm in diameter. DNA was extracted from these particles, and closed-circular DNA (Form I) was purified by centrifugation in CsCl containing ethidium bromide. The molecular weight of the DNA was about 5.0 x 10(6). A physical map of the HPV DNA was constructed using several restriction enzymes. The restriction endonuclease cleavage pattern of the HPV DNA was different from those of other types of HPV reported thus far, suggesting that the isolate was a new, as yet unclassified, HPV.
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PMID:New human papilloma virus isolated from epidermodysplasia verruciformis lesions. 628 Aug 58

Streptomyces erythreus NRRL 2338, the erythromycin producing microorganism, contains extrachromosomal (plasmid) DNA. Four different plasmids, pSE1, pSE2, pSE4 and pSE6 present in the wild-type strain have characteristic mobilities on agarose gel electrophoresis, molecular weight and restriction endonuclease digestion patterns. Treatment of the wild-type strain with ethidium bromide or acridine orange gave two variants, one that could not convert erythronolide B to 3 (alpha)-mycarosylerythronolide B and another than produced 2 approximately 3 times more erythromycin A than the parental strain. Although the plasmid DNA profile of these two variants is different from the wild-type strain, it is not possible to conclude that any of the structural genes for erythromycin biosynthesis are located on the plasmids of S. erythreus NRRL 2338.
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PMID:Plasmid DNA in the erythromycin producing microorganism, Streptomyces erythreus NRRL 2338. 628 Dec 25

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


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