Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. DNA polymerase activity is present in both nuclear and supernatant fractions prepared from rapidly dividing L929 mouse cells. 2. Nuclear preparations are 2-5 times more active with added native DNA as template and the supernatant fractions show an equivalent preference for heat-denatured DNA. 3. Isolated nuclei can carry on limited DNA synthesis in the absence of added template but are stimulated five- to ten-fold by addition of 50mug of native DNA per assay. 4. DNA polymerase activity can be released from intact nuclei by ultrasonic treatment or by extraction with 1.5m-potassium chloride. 5. The activities in nuclear and supernatant fractions, with their preferred templates, respond similarly to changes in pH and Mg(2+) and K(+) concentrations. 6. Maximal enzyme activity is approached with 40mug of DNA per assay and activation of the DNA template by treatment with deoxyribonuclease does not decrease the amount of DNA required to reach saturation. 7. The nuclear enzyme, incubated with native DNA, is markedly inhibited by the addition of heat-denatured DNA to the assay. In contrast, the supernatant DNA polymerase activity on denatured templates is not affected by the presence of native DNA. 8. The nuclear enzyme exhibits high activity in the absence of one or more deoxyribonucleoside triphosphates but this is much diminished after partial purification of the enzyme by precipitation at pH5 and fractionation on Sephadex G-200 columns. 9. The (3)H-labelled DNA products formed by Sephadex-purified nuclear and supernatant fractions, with their preferred templates, were found to be resistant to treatment with exonuclease I. Alkali-denaturation of the (3)H-labelled DNA products rendered them susceptible to attack by exonuclease I. 10. Analysis of the products on alkaline sucrose density gradients suggests that the newly synthesized material may not be covalently bound to the original DNA template. 11. By using their preferred templates the specific activity of supernatant fractions varies markedly with the position of the cells in the cell-cycle, but the specific activity of nuclear fractions varies only slightly.
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PMID:Characteristics of deoxyribonucleic acid polymerase activity in nuclear and supernatant fractions of cultured mouse cells. 553 Nov 81

Enzymes that release 5'-deoxyribose-5-phosphate (dRP) residues from preincised apurinic/apyrimidinic (AP) DNA have been collectively termed DNA deoxyribophosphodiesterases (dRPases), but they fall into two distinct categories: the hydrolytic dRPases and AP lyases. In order to resolve a number of conflicting reports in the dRPase literature, we examined two putative hydrolytic dRPases (Escherichia coli exonuclease I (exo I) and RecJ) and four AP lyases (E. coli 2, 6-dihydroxy-5N-formamidopyrimidine (Fapy) DNA glycosylase (Fpg) and endonuclease III (endo III), bacteriophage T4 endonuclease V (endo V), and rat polymerase beta (beta-pol)) for their abilities to (i) excise dRP from preincised AP DNA and (ii) incise AP DNA. Although exo I and RecJ exhibited robust 3' to 5' and 5' to 3' exonucleolytic activities, respectively, on appropriate substrates, they failed to demonstrate detectable dRPase activity. All four AP lyases possessed both dRPase and traditional AP lyase activities, albeit to varying degrees. Moreover, as best illustrated with Fpg, AP lyase enzymes could be trapped on both preincised and unincised AP DNA using NaBH(4) as the reducing agent. These results further support the assertion that the catalytic mechanism of the AP lyases, the beta-elimination reaction, does proceed through an imine enzyme-DNA intermediate and that the active site residues responsible for dRP release must contain primary amines. Further, these data indicate a biological significance for the beta-elimination reaction of DNA glycosylase/AP lyases in that they, in concert with hydrolytic AP endonucleases, can create appropriate gapped substrates for short patch base excision repair (BER) synthesis to occur efficiently.
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PMID:AP lyases and dRPases: commonality of mechanism. 1067 82

Exonuclease I was originally identified as a 5' --> 3' deoxyribonuclease present in fractionated extracts of Schizosaccharomyces pombe and Saccharomyces cerevisiae. Genetic analysis of exo1 mutants of both yeasts revealed no major defect in meiosis, suggesting that exonuclease I is unlikely to be the primary activity that processes meiosis-specific double-strand breaks (DSBs). We report here that exo1 mutants of S. cerevisiae exhibit subtle but complex defects in meiosis. Diploids containing a homozygous deletion of EXO1 show decreased spore viability associated with an increase in meiosis I nondisjunction, while intergenic recombination is reduced about twofold. Exo1p functions in the same pathway as Msh5p for intergenic recombination. The length of heteroduplex tracts within the HIS4 gene is unaffected by the exo1 mutation. These results suggest that Exo1p is unlikely to play a major role in processing DSBs to form single-stranded tails at HIS4, but instead appears to promote crossing over to ensure disjunction of homologous chromosomes. In addition, our data indicate that exonuclease I may have a minor role in the correction of large DNA mismatches that occur in heteroduplex DNA during meiotic recombination at the HIS4 locus.
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PMID:Decreased meiotic intergenic recombination and increased meiosis I nondisjunction in exo1 mutants of Saccharomyces cerevisiae. 1110 56

Schizophyllan is a beta-(1-->3)-D-glucan and can form a novel complex with some single-chains of DNAs. As the preceding paper revealed, the polynucleotide bound in the complex is more stable to nuclease-mediated hydrolysis than the polynucleotide itself (i.e., naked polynucleotide). This paper examined possibility to apply this complex to an antisense DNA carrier, using an in vitro (cell-free) transcription/translation assay. In this assay, we used a plasmid DNA coding a green fluorescence protein (GFP) and an antisense DNA designed to hybridize the ribosome-binding site in the GFP-coded mRNA. When the antisense DNA was administered as the complex, a lower GFP expression efficiency (or higher antisense effect) is observed over naked DNA. This is because the antisense DNA in the complex is protected from the attack of deoxyribonuclease. When exonuclease I, which specifically hydrolyzes single DNA chains, was present in the GEP assay system, the antisense effect was not changed for the complex while being weakened in the naked antisense DNA system. These results imply that the exonuclease I cannot hydrolyze the antisense DNA in the complex, while it can hydrolyze naked DNA to reduce its antisense effect.
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PMID:Antisense oligonucleotides bound in the polysaccharide complex and the enhanced antisense effect due to the low hydrolysis. 1496 45