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

---

Query: EC:3.1.22.1 (DNase II)
429 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The endonuclease DNase II preferentially attacks a limited and tissue-specific portion of chromosomal DNA. This material may be separated from the bulk of chromatin DNA by virtue of its solubility in 2 mM MgCl2. The Mg2+ soluble fraction forms a specific subset of DNA sequences and is enriched four to sevenfold in sequences coding for cytoplasmic poly(A)-containing RNA and globin messenger RNA (in globin-producing cells). The bulk (70--90%) of rapidly labelled RNA is found associated with the Mg2+-soluble fraction. Transcriptionally active, Mc2+-soluble chromatin is organized into repeating subunits of DNA (200 +/- 5 base pairs) and histone. Mc2+-soluble active subunits differ from the subunits or nucleosomes of non-transcribed regions in many respects: namely, chemical composition (non-histone protein and RNA), sedimentation properties, differential sensitivity to DNase I and the single-strand-specific nuclease S1, and optical melting behaviour. These results suggest that chromatin subunits adopt a new configuration during the process of transcription.
...
PMID:Organization of transcribed regions of chromatin. 2 80

The action of micrococcal nuclease, DNase I and DNase II on mouse TLT hepatoma chromatin revealing the periodicity of its structure as visualized by denaturing and non-denaturing gel electrophoresis, was consistent with the action of these enzymes on other chromatins. Micrococcal nuclease showed a complex subnucleosome fragment pattern based on multiples of 10 base pairs with a prominant couplet at 140/160 base pairs and the absence of the 80 base pair fragment. This couplet of the core and minimal nucleosome fragments was conspicuously present in the mononucleosomes found in the 11S fractions of a glycerol gradient centrifugation. DNase I and II produced a fairly even distribution of a 10 base pair increasing series of fragments to about 180 base pairs, a pattern also repeated in the DNA of nucleosome glycerol-gradient fractions. In limited digestions by these nucleases multinucleosomic DNA fragments are pronounced. These fragment lengths are multiples of an estimated average repeat length of nucleosome DNA of 180 base pairs. The action of the endogenous Mg/Ca-stimulated endonuclease produced only limited cuts in the hepatoma chromatin resulting primarily in multi-nucleosomic DNA fragment lengths and only upon lengthy digestion limited subnucleosomic, 10-base-pair multiple fragments are produced. The putative euchromatin-enriched fractions (50-75S) of the glycerol gradient centrifugation of autodigested chromatin, similarly, contained primarily the multinucleosomic DNA fragment lengths. These results are consistent with our previous electron microscopic demonstration that autodigested chromatin as well as the putative euchromatin-enriched fractions were composed of multi-nucleosomic chromatin segments containing a full complement of histones.
...
PMID:Periodicity and fragment size of DNA from mouse TLT hepatoma chromatin and chromatin fractions using endogenous and exogenous nucleases. 20 20

Rat-liver chromatin has bee fractionated into transcriptionally active and inactive regions [Gottesfeld et al. (1974) Proc. Nat. Acad. Sci. USA 71, 2193-2197] and the distribution of nuclease-resistant complexes in these fractions has been investigated. About half of the DNA of both fractions is resistant to attack by tne endonuclease DNase II. The nuclease-resistant structures of inactive chromatin are DNA-histone complexes (v-bodies) which sediment at 11-13 S. Template-active chromatin yields two peaks of nuclease-resistant nucleoprotein. These complexes sediment at 14 and 19 S, and contain DNA, RNA, histone, and nonhistone chromosomal proteins. Polyacrylamide gel electrophoresis reveals a complex pattern of chromatin proteins, suggesting that the complexes are heterogeneous in composition.
...
PMID:Structure of transcriptionally active chromatin. 106 Jan 19

An axiom of apoptosis is that increases in cytosolic Ca2+ activate a Ca2+/Mg(2+)-dependent endonuclease. However, when HL-60 human promyelocytic leukemia cells were incubated with the Ca2+ ionophore ionomycin in varied extracellular Ca2+, DNA digestion was independent of extracellular Ca2+. Under these conditions, intracellular Ca2+ concentrations did not correlate with the observed DNA digestion. In contrast, intracellular acidification correlated well with DNA digestion. These data indicate that increased intracellular Ca2+ is not the primary signal for endonuclease activation in all forms of apoptosis, but that intracellular acidification may be involved. The observed intracellular acidification is consistent with the involvement of deoxyribonuclease II in apoptosis.
...
PMID:Endonuclease activation during apoptosis: the role of cytosolic Ca2+ and pH. 132 91

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.
...
PMID:Number and distribution of methylphosphonate linkages in oligodeoxynucleotides affect exo- and endonuclease sensitivity and ability to form RNase H substrates. 247 96

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.
...
PMID:A protein inhibitor of acid deoxyribonucleases. 490 93

The histones isolated from the siliceous sponge Geodia cydonium have been separated using two electrophoretic techniques. A comparison of their mobilities with those of calf thymus and rat liver show that some Geodia histone species (H3, H1 and H1(0) exhibit electrophoretic variance. The results show, that as in other eukaryotic systems the sponge chromatin contains the core histones (H2A, H2B, H3 and H4) and the linker histone (H1). ADP-ribosylation of Geodia histones and separation of the individual histones by electrophoresis resulted in four histones being radiolabeled. Digestion of Geodia chromatin with endogenous endonuclease is shown to result in the formation of nucleosome particles containing approximately 200 base pairs of DNA. A major product of endogenous endonuclease digestion is a relatively stable 110 base pair intermediate. Incubation of chromatin with DNase II and separation of the products under denaturing conditions reveals 20 bands migrating at 10 base intervals.
...
PMID:Chromatin structure from the marine sponge Geodia cydonium. 631 75

Some characteristics of the postirradiation degradation of chromatin in the thymuses of mice were studied. The results proved that the main wave of chromatin degradation becomes evident between 2 and 4 h postirradiation, when considerable amounts of degradation products leach from nuclei during their isolation and are solubilized by lysis of nuclei. Similarly the degradation is manifested in the increase of salt-soluble chromatin fraction as well as of the fractions released from chromatin by various solutions (EDTA, heparin, deoxycholate, alkaline buffer). Later on, within 24 h after irradiation, only little changes in the relative amounts of the degradation products take place. Evidently only a certain thymocyte population is involved. Electrophoretic analyses of DNA fragments from various fractions in native and denatured state demonstrated that chromatin was degraded into nucleosomes and their oligomers by an endonuclease activity. The DNA bears, however, no signs of intranucleosomal regular single-strand fragmentation. This fact makes improbable the participation in this process of DNase I, DNase II and Ca,Mg-dependent endonuclease. No appreciable amount of smaller DNA fragments (products of further degradation of nucleosomes) were found even at 24 h postirradiation interval. Thus the nucleosomes and their oligomers must be considered as the only "long-lived" chromatin fragments in damaged lymphoid cells.
...
PMID:On the degradation of chromatin to nucleosomes in the thymocytes of X-irradiated mice. 637 91

The cellular basis for the enhanced sensitivity to ionising radiation and some DNA damaging chemicals in ataxia-telangiectasia (AT) cells is not clearly understood. Abnormalities in cell-cycle traverse, chromosome stability and DNA synthesis patterns have suggested that a chromatin associated defect may be the primary lesion in AT. This study involves an attempt to define such an anomaly by the use of a vital DNA specific bis-benzimidazole dye (Hoechst 33342) and deoxyribonuclease II as probes for chromatin organisation in intact and permeabilised human cells respectively. Despite similar DNA binding characteristics (determined by flow cytometry) of Ho33342 in normal and AT transformed fibroblasts, the AT cells show: (i) enhanced cell killing and increased accumulation of cells in G2 phase of the cell-cycle [both biological responses being relatively resistant in AT cells to modification by an inhibitor of poly (ADP ribosyl)ation], (ii) no resistance of de novo DNA synthesis to Ho33342-induced inhibition, (iii) elevated levels of slow-rejoining ligand-induced DNA strand-breaks, and (iv) enhanced expression of chromatin regions accessible to an exogenously supplied endonuclease. The results are interpreted on the basis that a chromatin anomaly of enhanced nuclease susceptibility, involving a minor fraction of the genome, may be a controlling factor in the expression of the various in vivo and in vitro characteristics of AT cells.
...
PMID:Relationship between a chromatin anomaly in ataxia-telangiectasia cells and enhanced sensitivity to DNA damage. 648 55

The acid deoxyribonuclease was isolated from Bombyx mori eggs and its physico-chemical properties were investigated. The enzyme purified 160-fold did not contain admixtures of phosphomono- and phosphodiesterases or ribonuclease. The molecular weight of the enzyme is 40 000 +/- 1000, isoelectric point lies at 6.5. The maximum activity is revealed at pH 5.2, 50 degrees. The DNAase is insignificantly activated by Mg2+ and is inhibited by Cu2+ and Zn2+. The enzyme preferentially hydrolyzes native DNA and is an endonuclease splitting DNA down to 5'-oligonucleotides.
...
PMID:[Isolation, purification and properties of acid deoxyribonuclease from silkworm Bombyx mori eggs]. 707 75


1 2 3 4 5 6 Next >>

---