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

Chicken reticulocyte (polychromatic primitive erythrocyte) and erythrocyte chromatin was fractionated by ultrasound shearing and salt precipitation into three fractions differing in their activities to support the in vitro RNA synthesis. The transcriptionally active fraction of chicken reticulocyte chromatin which represented only about 0.5% of the total nuclear DNA contained essentially all the chromatin-associated endogenous RNA. Approximately 2% of this endogenous reticulocyte RNA hybridized to globin cDNA probe and could be translated in vitro into polypeptides which coelectrophoresed with the in vitro translation product of isolated chicken globin mRNA or chicken globin marker. Each of the three fractions had a characteristic distribution of chromosomal proteins and endogenous RNA. Polyacrylamide gel electrophoresis of the chromosomal proteins showed differences in their distribution among individual fractions of the same cell type and among corresponding fractions of reticulocyte or erythrocyte chromatin. Antisera produced against dehistonized reticulocyte chromatin were specific for reticulocyte but not erythrocyte chromatin. When reacted with each of the differentially templating chromatin fractions, it was found that reticulocyte-specific antibodies were highly reactive with the template-active fraction of reticulocytes, but essentially nonreactive with any other reticulocyte fraction. This same antiserum was not significantly reactive toward any erythrocyte fraction. The antigenicity of the template-active fraction of reticulocytes was abolished after pronase or DNase II digestion, but only partially diminished after DNase I digestion.
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PMID:Immunological properties of fractionated avian erythroid nuclei. 67 Feb 33

Non-membranous HeLa cell nuclear ghosts, representing non-membranous nuclear envelope or 'skeletal' components, have been examined in whole-mount fashion by transmission electron microscopy. Major components of the ghosts include annuli with inner and outer diameters of 43 and 90 nm, respectively, which are consistent in dimensions with nuclear pore complexes. Also present are rod-like images (260 nm in length and 50 nm in width or diameter) representing either previously unobserved nuclear structures, or condensations of repeating functional units not otherwise observable. The annular and rod-like images were also observed when various steps in the ghost isolation procedure, such as the use of detergents, 0.5 M MgCl2 and polylysine attachment of the ghosts to electron-microscope grids, were circumvented. The annular and rod-like images are connected into linear and polygonal arrays by strands (15-30 nm in width) that are sensitive to DNase I and DNase II but resistant to nuclease S1. Thus, although the non-membranous ghosts from HeLa cells are composed primarily of protein, enzymic dissection indicates that their gross integrity is markedly dependent on double-stranded DNA. Nuclear ghosts prepared from a wide range of species including mammals, birds and plants, exhibited essentially the same components and organization.
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PMID:The ultrastructure of non-membranous nuclear ghosts. 70 96

Digestion of fixed metaphase chromosomes by endonucleases (micrococcal nuclease and DNase II) under optimal digestion conditions followed by Giemsa staining produces sharp banding patterns identical to G-bands. In 3H-thymidine labeled, synchronized metaphase cells of the chinese hamster (CHO line), the band induction is accompanied by the removal of DNA. The single strand specific nuclease S1 and DNase I do not produce such banding patterns.
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PMID:Responses of mammalian metaphase chromosomes to endonuclease digestion. 74 3

Rat liver chromatin is organized into regions of DNA which differ in degree of susceptibility to attack by the endonucleases DNase I and DNase II. The most nuclease-sensitive portion of chromatin DNA is enriched in transcribed sequences. This fraction may be separated from the bulk of chromatin by virtue of its solubility in solutions containing 2 mM MgCl2. Both transcribed and nontranscribed regions of chromatin are organized into repeating units of DNA and histone, which appear as 100 A beads in the electron microscope. The length of DNA in the repeat unit is the same for these two classes of chromatin (198 +/- 6 base pairs in rat liver); however, the subunits of active, Mg++-soluble chromatin differ from the nucleosomes of inactive regions of chromatin in several respects. Active subunits are enriched in nascent RNA and nonhistone protein and exhibit higher sedimentation values than the corresponding subunits of inactive chromatin.
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PMID:Structure of transcriptionally-active chromatin subunits. 90 2

Recent interest in the use of adriamycin-DNA complex as an approach to improve the therapeutic effectiveness and to reduce toxicity of adriamycin for cancer chemotherapy requires an in-depth understanding of the physicochemical and biochemical properties of such complexes. The interactions of adriamycin with single-strand polydeoxyribonucleotides, double-strand DNA, and double-strand ribodeoxyribopolynucleotide hybrids were therfore investigated. Association constants (Kapp) of adriamycin and polynucleotides were obtained. These data showed that the inherent variable in such complex lies in the composition of the polynucleotides. Alternate deoxyguanylate (dG)-deoxycytidylate (dC) sequence binds 7-fold better than alternate deoxyadenylate (dA)-deoxythymidylate (dT) sequence. Comparative studies of the hydrolysis of DNA duplexes by deoxyribonucleases I and II with and without adriamycin were also carried out. The rate of hydrolysis decreased in the order poly(dA-dT) greater than calf thymus DNA greater than poly(dG-dC) greater than poly(dA)-poly(dT) greater than poly(dG)-poly(dC) for DNase I and poly(dA)-dT) greater than calf thymus DNA greater than poly(dG-dC) greater than poly(dA)-poly(dT) greater than poly(dG)-poly(dC) for DNase II. Intercalation of adriamycin to deoxyribopolynucleotide duplex resulted in inhibition of DNase II two to three times more than tat of DNase I. On the other hand, intercalation of adriamycin to homodeoxypolynucleotide duplex poly(dA)-poly(dT) and poly(dG)-poly(dC) enhanced the DNase I hydrolysis. If DNase I activity could be related to serum DNase and DNase II related to tumor lyososomal DNase as in the endocytosis mechanism proposed by Trouet et al. (Cancer Chemotherapy Rept., 59: 260, 1975), the best adriamycin carrier suggested by this investigation could be poly(dA)-poly(dT) and poly(dG-dC). It is also suggested in this study that adriamycin-RNA-DNA hybrid could be of interest as an antiviral agent by a similar release mechanism via RNase H, an enzyme associated with viral reverse transcriptase.
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PMID:Effect of deoxyribonuclease on adriamycin-polynucleotide complexes. 97 96

DNA- and RNA-concentrations, as well as in vitro activities of DNase I (EC 3.1.4.5), DNase II (EC 3.1.4.6), and DNase I inhibitor, have been determined in 63 spontaneous (man) and 22 experimentally induced (rat) nervous system blastomas of various types and of different degrees of malignancy. Generally, a distinct elevation of DNA concentrations and of the ratio (Q) of DNase II- to DNase I-activities has been observed when compared with control values. A statistically significant relationship could be demonstrated between increase of DNA concentrations and Q in experimentally induced neurinomas of rats as well as in human astrocytomas and glioblastomas. Whereas the increase of Q may be a biochemical expression of elevated DNA synthesis of tumour cells, no conclusions can be drawn as to the role of DNases in the process of malignant transformation.
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PMID:[Deoxyribonucleases in spontaneous and experimental tumors of the nervous system]. 118 37

The effect of actinomycin on the structure of DNA fragments containing the sequences (AT)5GC(AT)5, (TA)5GC(TA)5, A9GCT9, and T9GCA9, cloned into the SmaI site of pUC19, has been studied by footprinting analysis using a variety of probes known to be sensitive to DNA structure. In each case clear footprints are found around the central GC sites. DNase I cleavage of fragments containing alternating AT shows much greater cutting at ApT than TpA; in the presence of actinomycin, although this preference is retained, there is a large increase in the cutting efficiency at the closest TpA steps. DNase I cleavage in homopolymeric regions of A and T, which is normally very poor, is greatly enhanced by drug binding. With T9GCA9 the enhancements are propagated in both directions, whereas changes are only found to the 5'-side of the GC site in A9GCT9. The results are confirmed by similar experiments with micrococcal nuclease and DNase II. Small increases in sensitivity to diethylpyrocarbonate are found at adenines proximal to GC. Experiments performed at 4 degrees C suggest that conformational changes are a necessary consequence of drug binding.
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PMID:The effects of actinomycin on the structure of dAn.dTn and (dA-dT)n regions surrounding its GC binding site. A footprinting study. 170 17

Regions of An.Tn, (GA)n.(TC)n, and (GT)n.(AC)n have been cloned into the SmaI (CCC/GGG) site of plasmid pUC19. HindIII-EcoRI restriction fragments containing these inserts have been used as substrates for footprinting experiments using DNase I, DNase II, and micrococcal nuclease as probes. These present good mithramycin binding sites (GGG) flanking repetitive regions to which the drug does not bind. In each case, mithramycin footprints are observed at the CCC/GGG sites, which are not affected by the nature of the surrounding sequences. Some weaker binding is detected at TCGA and ACCA sites and at regions of alternating GA. No binding is found to regions of alternating GT. An.Tn inserts (n = 23 or 69) are normally resistant to cleavage by all these probes; in the presence of mithramycin, a dramatic increase in DNase I cleavage is observed throughout the entire insert and is indicative of an alteration in DNA structure. Similar changes are seen with DNase II and micrococcal nuclease. These changes cannot be explained by invoking changes in the ratio of free substrate to cleavage agent. In contrast, cleavage of (GA)n.(CT)n and (GT)n.(AC)n inserts is not affected by drug binding. The results are consistent with a model in which mithramycin causes dramatic changes in the width of the DNA minor groove, generating a structure which has some properties of A-DNA, and suggest that this can be propagated into surrounding DNA regions in a sequence-dependent manner. The structural alterations with An.Tn are highly cooperative and can be transmitted over at least three turns of the DNA helix.
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PMID:Effects of the antitumor antibiotic mithramycin on the structure of repetitive DNA regions adjacent to its GC-rich binding site. 182 82

Phosphorus-31 NMR has been applied to the characterization of terminal phosphates on fragments of calf thymus DNA induced by three different nuclease systems: DNase I, DNase II and the artificial nuclease 'Mn-TMPyP/KHSO5'. In this last case, the oxidative damage to deoxyribose leads to two monophosphates esters (at the 3' and 5' ends) on both sides of the cleavage site. This method constitutes a promising approach to visualise the phosphate termini generated in DNA or RNA cleavage by cytotoxic drugs or chemical nucleases and provides a novel insight into the molecular aspects of their mechanism of action.
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PMID:31P NMR characterization of terminal phosphates induced on DNA by the artificial nuclease 'Mn-TMPyP/KHSO5' in comparison with DNases I and II. 205 47

DNA fragments containing (AT)n inserts cloned adjacent to putative mithramycin binding sites have been examined by footprinting experiments using a variety of nucleases in the presence of the drug. The results demonstrate that mithramycin induces a DNA structural change which renders adjacent (AT)n sequences sensitive to attack by DNase II. Significant changes are also revealed with DNase I and micrococcal nuclease. The results are consistent with a model in which mithramycin opens the DNA minor groove changing it to a structure which is locally more like A-DNA.
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PMID:The GC-selective ligand mithramycin alters the structure of (AT)n sequences flanking its binding sites. 214 99


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