Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.22.1 (DNase II)
 429 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bleomycin (BLM) exclusively affects thymidine-containing compounds such as DNA and polydeoxyribonucleotides by releasing free thymine and leaving aldehyde functions. Molecular morphology and base sequence of the DNA strongly influence BLM activity. High BLM concentrations, besides modifying DNA into oligothyminic or athyminic nucleic acids, cause strand scissions. Enzymatic DNA and RNA synthesis is strongly influenced by BLM. The inhibition in DNA-dependent DNA polymerase and DNA-dependent RNA polymerase assays is of the non-competitive type. Protein biosynthesis in in vitro systems is not affected by BLM even at high concentrations. BLM turns out to be a strong inhibitor of DNase I and of DNase II; the inhibition is of the competitive type. The enzymatic activities of nucleases using RNA as substrate (RNase A, RNase B, Rnase T1, venom phosphodiesterase I and spleen phosphodiesterase II) are not influenced by this antibiotic. The antibiotic reduces cell proliferation (L5178y mouse lymphoma cells) in vitro in low concentrations by cytostasis and at higher concentrations by cytotoxicity. In BLM-treated L5178y cells, DNA synthesis is strongly reduced, while RNA and protein synthesis are not affected. In vivo, using growing quail oviducts, cell proliferation and cytodifferentiation are markedly inhibited after BLM treatment. This is attributed to the observed inhibition of DNA synthesis. RNA and protein synthesis as well as gene expression are not influenced by BLM under the conditions used. The selective inhibition of DNA synthesis in vivo may be caused by the following mechanisms: (1) competition of BLM with RNA; (2) blocking of the accessibility of DNA in chromatin to BLM, and (3) dependence from the repair processes. BLM inhibits growth of sarcomas, induced by oncogenic RNA viruses in vivo; well-developed tumours show regression after BLM treatment. Transformation of chick embryo fibroblasts by oncogenic RNA viruses in vitro and growth of these viruses is blocked by BLM; the most sensitive period for BLM inhibition is the time during the first period (integration of viral genome into cellular genome?) after infection.
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PMID:Effect of bleomycin on DNA, RNA, protein, chromatin and on cell transformation by oncogenic RNA viruses. 6 69

To provide information on the role of nucleases in oncogenic virus infection, the activities of 3'-nucleotide phosphodiesterase (3'-NPDase), 5'-nucleotide phosphodiesterase (5'-NPDase), acid deoxyribonuclease (DNase II), and 3',5'-cyclic AMP phosphodiesterase (cAMPDase) in spleen extracts of murine sarcoma virus-infected C57BL/6 inbred mice were studied. At the peak of tumor growth and of the cell-mediated cytotoxic response (CMC) against tumor-associated antigens, 3'-NPDase, 5'-NPDase, and DNase II all showed depressed activities in the spleen, whereas the activity of cAMPDase in the spleen increased at the peak of CMC and remained elevated thereafter. Serum enzyme activities of the infected mice were also determined, and only 3'-NPD-ase in serum correlated well with CMC. Inasmuch as the correlation of the tumor growth with CMC was established in this system, further study on tumors with variance between CMC and growth is necessary to determine if serum 3'-NPDase is a useful biochemical marker for CMC in vivo.
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PMID:Nucleases and adenosine 3',5'-cyclic monophosphate phosphodiesterase activities in murine sarcoma virus (Moloney)-infected mice. 21 66

The following procedures have been used to prepare fifteen modified dinucleoside monophosphates: (a) bisulfite-catalyzed transamination with aniline to give an N4-phenylcytidine (CPh), (b) bisulfite-catalyzed transamination with beta-naphthylamine to give an N4-beta-naphthylcytidine (CbetaN), (c) alkylation with 7-bromomethylbenz[a] anthracene to afford a 7(benz[a]anthryl-7-methyl)guanosine (GMBA), and (d) reaction with N-acetoxy-2-acetylaminofluorene to give an 8-(N-2-fluorenylacetamido)guanosine (GAAF). The compounds prepared were A-CPh, CPh-A, CPh-G, U-CPh, CPh-U, A-CbetaN, CbetaN-A, G-CbetaN, CbetaN-G, U-CbetaN, CbetaN-U, GMBA-U, U-GMBA, GAAF-U, and U-GAAF. All of the modified compounds were hydrolyzed to the expected monomers with venom and spleen exonucleases. Hydrolysis by micrococcal nuclease was inhibited in the following cases: A-CPh, A-CbetaN, U-GMBA, and U-GAAF. The first three reactions above were applied to denatured calf thymus DNA to prepare modified DNA samples containing from 0.3 to 2.0% bound aromatic residues. The modified nucleic acids were completely hydrolyzed to nucleosides by the combination of venom exonuclease, deoxyribonuclease I and alkaline phosphatase. The same results were obtained with a combination of spleen exonuclease, deoxyribonuclease II, and alkaline phosphatase. Hydrolysis of the modified nucleic acids by micrococcal nuclease and alkaline phosphatase afforded primarily nucleosides, with some dinucleoside monophosphates. The amount of the latter did not exceed that found in the hydrolysis of control DNA, however. Other workers have observed inhibition of enzymatic hydrolysis of nucleic acids modified by aromatic carcinogens. We postulated that their results may have been caused by cross-links, which were avoided in our studies.
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PMID:Preparation and enzymatic hydrolysis of dinucleoside monophosphates and DNA modified with aromatic residues. 55 43

Oligodeoxynucleotides with different arrangements of methylphosphonate linkages were examined for nuclease sensitivity in vitro, stability in tissue culture, and ability to form RNase H-sensitive substrates with complementary RNA. After nuclease treatment, resistance was demonstrated by the ability to alter the electrophoretic mobility of a labeled complementary phosphodiester oligodeoxynucleotide. Both 5'- and 3'-exonuclease activities were retarded by methylphosphonate linkages. Methylphosphonate-containing oligodeoxynucleotides with 1-5 adjacent phosphodiester linkages were tested as substrates for the endonucleases DNase I and DNase II. The results indicated that a span of three or fewer contiguous internal phosphodiester linkages led to the greatest resistance to endonuclease. However, in serum-supplemented culture medium half-lives of these oligodeoxynucleotides were independent of the number of contiguous phosphodiester linkages. Methylphosphonate-containing oligodeoxynucleotides were hybridized to RNA runoff transcripts and tested as substrates for RNase H. The results indicated that a span of three internal phosphodiester linkages in the oligodeoxynucleotide was necessary and sufficient to direct cleavage of the RNA in the duplex.
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PMID:Number and distribution of methylphosphonate linkages in oligodeoxynucleotides affect exo- and endonuclease sensitivity and ability to form RNase H substrates. 247 96

Phosphodiesterase I [EC 3.1.4.1] was purified from normal human urine in a highly purified state free from phosphodiesterase II, RNase, DNase I, DNase II, and phosphatase by column chromatographies of DEAE-Toyopearl, butyl-Toyopearl, Affi-Gel blue, and Sephadex G-150. The molecular weight of the enzyme was 1.9 x 10(5) and the pH optimum around 9.0 with p-nitrophenyl deoxythymidine 5'-phosphate as the substrate. The enzyme hydrolyzed the 3'-5' linkage of various dinucleoside monophosphates at approximately the same rate and the phosphodiester bonds of cyclic 3',5'-mononucleotides to produce mononucleoside 5'-phosphate. The enzyme also hydrolyzed ADP to 5'-AMP and Pi, ATP to 5'-AMP and PPi, and NAD+ to 5'-AMP and NMN. The enzyme activity was abolished by removal of metal ions with EDTA, and the metal-free enzyme was reactivated on the addition of Zn2+. The enzyme activity was also abolished by some reducing agents and the inhibition was reversed by Zn2+. The metal-free enzyme was less stable than the native enzyme, and Zn2+ and Co2+ restored the stability of the metal-free enzyme to the level of the native enzyme. The enzyme degraded oligonucleotides and high molecular nucleotides stepwise from the 3'-termini to give 5'-mononucleotides. The enzyme hydrolyzed single-stranded DNA more preferentially than double-stranded DNA. The enzyme also nicked superhelical covalently closed circular phi X174 DNA to yield first open circular DNA and then linear DNA.
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PMID:Phosphodiesterase I in human urine: purification and characterization of the enzyme. 282 85

The Rp- and Sp-diastereomers of the phosphorothioate-containing oligonucleotide d[ApAp(S)ApA] have been synthesized. They and the tetramer d[ApApApA] were tested as substrates for staphylococcal nuclease, DNase II and spleen phosphodiesterase. For digestions with DNase I these oligonucleotides were converted to the 5'-phosphorylated derivates. The reactions with the nucleases were analysed by HPLC. The phosphorothioate groups of both diastereomers were resistant to the action of staphylococcal nuclease, DNase I and DNase II. While the phosphorothioate group of the Rp-diastereomer was resistant to the action of spleen phosphodiesterase, the Sp-diastereomer was hydrolysed at an estimated rate 1/100 the rate of cleavage of the unmodified tetramer. The presence of the phosphorothioate group in the center of the molecule affected the rate of hydrolysis of neighbouring phosphate groups for some enzymes. In particular, very slow release of 3'-dAMP from the Rp-diastereomer occurred on incubation with staphylococcal nuclease but the Sp-diastereomer was completely resistant. DNase II produced 3'-dAMP quite rapidly from both diastereomers of d[ApAp(S)ApA] and DNase I released 5'-dAMP from both diastereomers of d[pApAp(S)ApA] only slowly.
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PMID:Inhibition of deoxyribonucleases by phosphorothioate groups in oligodeoxyribonucleotides. 285 May 41

S-(1-Acetoxymethyl)glutathione (GSCH(2)OAc) was synthesized and used as a model for the reaction of glutathione (GSH)-dihaloalkane conjugates with nucleosides and DNA. Previously, S-[1-(N(2)-deoxyguanosinyl)methyl]GSH had been identified as the major adduct formed in the reaction of GSCH(2)OAc with deoxyguanosine. GSCH(2)OAc was incubated with the three remaining deoxyribonucleosides to identify other possible adducts. Adducts to all three nucleosides were found using electrospray ionization mass spectrometry (ESI MS). The adduct of GSCH(2)OAc and deoxyadenosine was formed in yield of up to 0.05% and was identified as S-[1-(N(7)-deoxyadenosinyl)methyl]GSH. The pyrimidine deoxyribonucleoside adducts were formed more efficiently, resulting in yields of 1 and 2% for the GSCH(2)OAc adducts derived from thymidine and deoxycytidine, respectively, but their lability prevented their structural identification by (1)H NMR. On the basis of the available UV spectra, we propose the structures S-[1-(N(3)-thymidinyl)methyl]GSH and S-[1-(N(4)-deoxycytidinyl)methyl]GSH. Because adduct degradation occurred most rapidly at alkaline and neutral pH values, an enzymatic DNA digestion procedure was developed for the rapid hydrolysis of DNA to deoxyribonucleosides at acidic pH. DNA digests were completed in less than 2 h with a two-step method, which consisted of a 15 min incubation of DNA with high concentrations of deoxyribonuclease II and phosphodiesterase II at pH 4.5, followed by incubation of resulting nucleotides with acid phosphatase. Analysis of the hydrolysis products by HPLC-ESI-MS indicated the presence of the thymidine adduct.
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PMID:Characterization of nucleoside and DNA adducts formed by S-(1-acetoxymethyl)glutathione and implications for dihalomethane-glutathione conjugates. 1136 61

The dihalomethane CH(2)Cl(2) is an industrial solvent of potential concern to humans because of its potential genotoxicity and carcinogenicity. To characterize DNA damage by dihalomethanes, a rapid DNA digestion under acidic conditions was developed to identify alkali labile DNA-dihalomethane nucleoside adducts using HPLC-electrospray mass spectrometry. DNA digestion worked best using pH 5.0 sodium acetate buffer, a 30 min incubation with DNase II and phosphodiesterase II, and a 2 h acid phosphatase digest. DNA was modified with S-(1-acetoxymethyl)glutathione (GSCH(2)OAc), a reagent modeling activated dihalomethanes. Adducts to G, A, and T were detected at high ratios of GSCH(2)OAc/DNA following digestion of the DNA with the procedure used here. The relative efficacy of adduct formation was G > T > A >> C. The four DNA nucleosides were also reacted with the dihalomethanes CH(2)Cl(2) and CH(2)Br(2) in the presence of glutathione (GSH) and GSH S-transferases from bacteria (DM11), rat (GST 5-5), and human (GST T1-1) under conditions that produce mutations in bacteria. All enzymes formed adducts to all four nucleosides, with dGuo being the most readily modified nucleoside. Thus, the pattern paralleled the results obtained with the model compounds GSCH(2)OAc and DNA. CH(2)Cl(2) and CH(2)Br(2) yielded similar amounts of adducts under these conditions. The relative efficiency of adduct formation by GSH transferases was rat 5-5 > human T1-1 > bacterial DM11, showing that human GSH transferase T1-1 can form dihalomethane adducts under the conditions used. Although the lability of DNA adducts has precluded more sophisticated experiments and in vivo studies have not yet been possible, the work collectively demonstrates the ability of several GSH transferases to generate DNA adducts from dihalomethanes, with G being the preferred site of adduction in both this and the GSCH(2)OAc model system.
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PMID:Formation and mass spectrometric analysis of DNA and nucleoside adducts by S-(1-acetoxymethyl)glutathione and by glutathione S-transferase-mediated activation of dihalomethanes. 1472 18