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)

Mutants of Diplococcus pneumoniae that lacked the two major deoxyribonucleases of the cell-one an endonuclease, the other an exonuclease preferentially active on native deoxyribonucleic acid (DNA)-were obtained. The development of a method for detecting mutant colonies, based on the binding of methyl green to DNA, facilitated isolation of the mutants. Neither enzyme was essential for growth of the cells, for repair of ultraviolet damage, or for any phase of DNA-mediated transformation. Residual deoxyribonuclease activity in the double mutant corresponded to an exonuclease, approximately one-fifth as active as the major exonuclease, that attacked native and denatured DNA equally well. This activity appeared to be associated with the DNA-polymerase enzyme. A mutant that apparently lacked a cell wall lytic enzyme was also fully transformable. A mutant strain that was four times more sensitive to ultraviolet light than the wild type also transformed normally. Recipient cells of this strain were deficient in the repair of ultraviolet-irradiated transforming DNA. Mutants were found which, unlike the wild type, integrated donor markers only with high efficiency, thereby indicating that a particular cellular component that is susceptible to loss by mutation, such as an enzyme, is responsible for low integration efficiency.
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PMID:Mutants of Diplococcus pneumoniae that lack deoxyribonucleases and other activities possibly pertinent to genetic transformation. 439 1

We have determined the levels of DNA polymerase, DNA ligase, a DNase acting on single-stranded DNA, an endonuclease making single-strand breaks in double - stranded DNA and polynucleotide kinase in fibroblasts obtained from nine normal persons and from nine patients with Xeroderma Pigmentosum; the pathological lines belong to the different described clinical forms and to the three different complementation groups described so far. All the enzymes are present in the normal lines and in the Xeroderma lines. The levels are quite variable, but the values obtained in the pathological lines lie within the ones observed in the normal population.
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PMID:Levels of some enzymes acting on DNA in xeroderma pigmentosum. 441 76

The stimulation of human lymphocytes with phytohaemoagglutinin induces the appearance or increase of several enzymes of DNA metabolism [Pedrini etal., Biochem. Biophys. Res. Comm., 47:1221(1972)]. With long times of stimulation, two phenomena are observed; an increase in the levels of DNA polymerase, of a DNase acting on single-stranded DNA, and of an endonuclease, occurring between the third and fourth day, in parallel with a wave of DNA synthesis;a second wave of increase of the same enzymes and of DNA ligase,occurring between the fifth and eight day when the DNA replication rate, as measured by thymidine-pulses, has decreased to values close to the background.
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PMID:Evidence for two waves of induction of DNA enzymes in stimulated human lymphocytes. 445 22

Spheroplasts are insensitive to colicin E(2) and do not show deoxyribonucleic acid (DNA) degradation even in the presence of massive amounts of E(2). However, when both endonuclease I and E(2) were present, spheroplast DNA was degraded by an endonucleolytic activity which gave rise primarily to double-strand DNA cleavages, producing fragments having an average molecular weight of 9 x 10(6). Pancreatic ribonuclease could substitute for colicin E(2) in the reconstitution system, but pancreatic deoxyribonuclease could not replace endonuclease I. However, colicin E(2) could not activate transfer ribonucleic acid-inhibited endonuclease I in an in vitro system where pancreatic ribonuclease caused full stimulation.
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PMID:Reconstitution of colicin E2-induced deoxyribonucleic acid degradation in spheroplast preparations. 459 17

A protein extracted and partially purified (about 100-fold) from mouse liver is able to inhibit the acid DNases from different tissues and species, whereas pancreatic DNase and E. coli endonuclease I are not inhibited. The acid DNase displays typical Michaelis-Menten kinetics in the absence of this inhibitor, but the kinetics become sigmoidal in its presence. The existence of a DNase-inhibitor complex is demonstrated by physicochemical experiments. Moreover, the inhibitor is able to reactivate the DNase treated by urea, probably through a reassociation of the inactive monomers to a dimeric state. An allosteric model in which the DNase-inhibitor complex is composed of catalytic (DNase) and regulatory (inhibitor) subunits could explain these data.
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PMID:A protein inhibitor of acid deoxyribonucleases. 490 93

In bacterial strains containing the deoxyribonuclease endonuclease I (endonuclease I(+) strains), 70 to 80% of the injected superinfecting T-even phage deoxyribonucleic acid (DNA) is rapidly degraded to oligonucleotides having an average chain length of 8, the same value as that obtained by endonuclease I digestion of purified T-even phage DNA in vitro. In endonuclease I(-) strains, less than 5% of the injected superinfecting T-even phage DNA is degraded to acid-soluble components. The superinfecting phage DNA is, however, fragmented into a large segment having a molecular weight of about 90 x 10(6) and 30 or more small acid-insoluble segments having molecular weights of less than 10(6). In both endonuclease I(+) and endonuclease I(-) strains, over 80% of the DNA from adsorbed primary T2 or T4 phage, but only 50% of the DNA from adsorbed superinfecting T2 or T4 phage, is injected. Superinfecting T4 are genetically excluded as efficiently from endonuclease I(-) strains as they are from endonuclease I(+) strains. The excluded phage cannot complement defects in either early or late gene functions carried by the primary phage. The induction of both superinfection breakdown and superinfection exclusion requires a period of protein synthesis between primary infection and addition of the superinfecting phage. These observations seem best explained by failure of superinfecting DNA to enter the host cell cytoplasm, presumably as a result of changes in the cell envelope induced by the primary phage.
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PMID:Breakdown and exclusion of superinfecting T-even bacteriophage in Escherichia coli. 495 Jun 90

High-resolution autoradiography has been employed to localize the nonsolubilized but genetically excluded deoxyribonucleic acid (DNA) of T4 bacteriophage superinfecting endonuclease I-deficient Escherichia coli. This DNA was found to be associated with the cell envelope (this term is used here to include all cellular components peripheral to and including the cytoplasmic membrane); in contrast, T4 DNA in primary infected cells, like host DNA in uninfected E. coli, was found to be near the cell center. The envelope-associated DNA from super-infecting phage was not located on the outermost surface of the cell since it was insensitive to deoxyribonuclease added to the medium. These results suggest that DNA from superinfecting T-even phage is trapped within the cell envelope.
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PMID:Localization of parental deoxyribonucleic acid from superinfecting T4 bacteriophage in Escherichia coli. 495 Jul 3

The biological activity of UV-inactivated Bacillus subtilis DNA is partly restored after incubation with a UV-specific endonuclease from Micrococcus lutens in conjunction with DNA polymerase and DNA ligase, both isolated from Escherichia coli. The restored activity is not further increased by photoreactivation. Pyrimidine dimers are specifically liberated when irradiated DNA is exposed to the three enzymes. None of these effects is observed when pancreatic DNase is used instead of UV-specific endonuclease.
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PMID:In vitro excision-repair of ultraviolet-irradiated transforming DNA from Bacillus subtilis. 500 81

The endonucleolytic action of a deoxyribonuclease activity in rabbitpox and vaccinia virus was established by change in sedimentation rate of denatured (3)H-lambda deoxyribonucleic acid substrate. The presence of two deoxyribonuclease activities in pox-virus is confirmed. Exo- and endonuclease activities are unmasked by treatment of purified virus with the detergent Nonidet P-40 and further enhanced by treatment of viral "cores" with trypsin.
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PMID:Virus-associated nucleases: evidence for endonuclease and exonuclease activity in rabbitpox and vaccinia viruses. 501 15

Various digests of (32)P-labelled DNA were examined by two-dimensional ionophoresis on cellulose acetate and DEAE-cellulose paper. The products from digestion with pancreatic deoxyribonuclease and Neurospora crassa endonuclease were qualitatively closely similar, but very complex, and were used to investigate the mapping behaviour of nucleotides in various ionophoretic systems. Ionophoresis on DEAE-cellulose paper in triethylamine carbonate, pH 9.7, followed by ionophoresis in the second dimension at pH1.9 gave high resolution of nucleotides in very complex mixtures and permitted the fractionation of larger quantities than is possible on cellulose acetate. High resolution of nucleotides in compact spots was obtained with two-dimensional ionophoresis on cellulose acetate and AE-cellulose paper, a system that is a useful supplement to those based on DEAE-cellulose paper.
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PMID:Nucleotide 'maps' of digests of deoxyribonucleic acid. 547 26


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