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:3.1.22.1 (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.
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PMID:Organization of transcribed regions of chromatin. 2 80

Chromatin from trout testis at an early stage of development was digested with DNase II (deoxyribonucleate 3'-oligonucleotidohydrolase; EC 3.1.4.6), and the solubilized products were fractionated into Mg2+-soluble and -insoluble components. An examination of the histones from these fractions by one- and two-dimensional polyacrylamide gels showed that the highly acetylated species of histone H4 (di-, tri-, and tetra-acetylated) were associated mainly with the Mg2+-soluble material. Digestion of this chromatin fraction with pancreatic ribonuclease converted more than half of it to an insoluble state, and the acetylated H4 remained associated with the precipitated fraction. No changes in the other histones were noted, but two other basic proteins were also found to be associated with the Mg2+-soluble fraction. Since this fraction is enriched in transcribing gene sequences, it is concluded that the histone H4 of active genes is present in a highly acetylated state.
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PMID:Acetylated histone H4 is preferentially associated with template-active chromatin. 27 72

Though DNase does not contain any cysteine residues, incubation of the enzyme with 2-nitro-5-thiocyanobenzoic acid in the presence of Ca2+ at pH values above 7.5 results in an irreversible inactivation of the enzyme. The inactivation also occurs when Ca2+ is replaced by Mg2+, but not in their absence. Amino acid analyses after acid hydrolyses of the completely inactivated ant the native enzymes show no significant differences in composition, including tryptophan and half-cystine residues. However, sodium dodecyl sulfate gel electrophoresis indicates enzyme cleavage by the treatment with 2-nitro-5-thiocyanobenzoic acid. This reagent does not inactivate chymotrypsin and lysozyme, and under conditions where bovine DNase is inactivated, does not inactivate other nucleases such as ribonuclease, snake venom phosphodiesterase, and spleen acid DNase. However, it inactivates malt DNase and can, therefore, be considered a specific inhibitor of DNase I. The inactivation kinetics is pseudo-first order, resembling Michaelis-Menten, with an affinity constant of 16.7 mM. It is the cyano group, not the thionitrobenzoic acid of 2-nitro-5-thiocyanobenzoic acid that reacts to form cyano-DNase.
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PMID:Inactivation of bovine pancreatic DNase by 2-nitro-5-thiocyanobenzoic acid. I. A novel inhibitor for DNase I. 48 54

It has been demonstrated by digestion studies with micrococcal nuclease that reconstitution of complexes from DNA and a mixture of the four small calf thymus histones H2A, H2B, H3, and H4 leads to subunits closely spaced in a 137 +/- 7-nucleotide-pair register. Subunits isolated from the reconstituted complex contain nearly equimolar amounts of the four histones and sediment at 11.6S. On DNase I digestion both the reconstituted complex and the separated subunits gave rise to series of single-stranded DNA fragments with a 10-nucleotide periodicity. This indicates that the reconstitution leads to subunits very similar to nucleosome cores. Nucleosome cores closely spaced in a 140-nucleotide-pair register were also obtained upon removal of histone H1 from chromatin by dissociation with 0.63 M NaCl and subsequent ultracentrifugation. In reconstitution experiments with all five histones (including histone H1) our procedure did not lead to tandemly arranged nucleosomes containing about 200 nucleotide pairs of DNA. In the presence of EDTA, DNase II cleaved calf thymus nuclei and chromatin at about 200-nucleotide-pair intervals whereas in the presence of Mg2+ cleavage at intervals of approximately half this size was observed. The change in the nature of the cleavage pattern, however, was no longer found after removal of histone H1 from chromatin. This indicates that H1 influences the accessibility of DNase II cleavage sites in chromatin. This finding is discussed with respect to the influence of histone H1 on chromatin superstructure.
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PMID:Closely spaced nucleosome cores in reconstituted histone.DNA complexes and histone-H1-depleted chromatin. 63 Nov 38

Deoxyribonuclease II has been purified through five fractionation steps from the human lymphoblast cell line K562. Isolation included DEAE-cellulose and heparin-agarose chromatography followed by fractionation on Mono-S, Mono-Q and Superose-12 FPLC columns. In an extension of previous studies, deoxyribonuclease II was found to introduce a much higher proportion of single-strand nicks relative to double-strand breaks into supercoiled DNA than has been reported for linear DNA. Application of DNA sequencing techniques has further revealed a unique resistance of 3' termini to hydrolysis by this enzyme. Deoxyribonuclease II cleaves at every available site along the duplexed portion of a paired oligonucleotide substrate with the exception of the last four nucleotides. Consistent with previous results, this deoxyribonuclease II is active at low pH in the absence of Mg2+ and is not inhibited by EDTA, but complete inhibition is observed with 100 microM Fe3+. Likewise we confirmed the presence of 3'-phosphoryl termini on the DNA cleavage products since they failed to function as primers for DNA synthesis catalyzed by Escherichia coli DNA polymerase I.
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PMID:Mechanism of action of deoxyribonuclease II from human lymphoblasts. 176 Oct 47

DNA repair replication has been previously demonstrated to occur in mouse spermatocytes during the pachytene stage. The results reported in this study provide a more detailed characterization of pachytene repair by focusing upon specific properties of the sites of replication. Our data demonstrate that single-strand breaks persist within replicated sequences throughout a period which corresponds to a defined interval of the pachytene stage. A large fraction of the sites may be nicked more than once within the same DNA strand, allowing the selective release of replicated DNA sequences from gently denatured spermatocyte DNA. DNA fragments thus prepared from pachytene spermatocytes are not of random sequence composition, but are derived from a specific subset of the mouse genome. Sites of replication are also associated with chromatin of distinctive structure in pachytene spermatocytes, as evidenced by the sensitivity of replicated chromatin to DNase II, and its solubility in the presence of Mg2+. In each of these respects, sequences replicated in pachytene spermatocytes closely resemble their counterparts in the Lilium genome.
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PMID:DNA synthesis at selective sites during pachytene in mouse spermatocytes. 373 43

The process of chromatin compactization in nuclei at different concentrations of Mg2+ and/or Na+ ions has been investigated by analysis of chromatin cleavage pattern with DNase II. Nuclei of cells that differ in transcriptional activity and have different nucleosome DNA repeat length such as pigeon erythrocytes, rat cerebellum neurons and pigeon brain cortex neurons were studied. In the presence of 0-3 mM MgCl2 several compactization levels of nucleosomal fiber were revealed in chromatin of pigeon erythrocyte and rat cerebellum nuclei (nucleosome DNA repeat of 210 +/- 3 and 202 +/- 3 nucleotide pairs, respectively). Each of these levels are characterized by different types of periodical DNA fragmentation of chromatin with DNase II, namely formation of nucleosomal, "half-nucleosomal" (fragmentation via a 100 nucleotide pairs interval), and dinucleosomal periodicities. Similar compactization stages were shown also for isolated erythrocyte chromatin. In 0-3 mM MgCl2 chromatin of pigeon brain cortex neuron nuclei having nucleosome DNA repeat size 164 +/- 3 nucleotide pairs is cleaved with DNase II producing only a "half-nucleosomal" periodicity. A pattern of chromatin fragmentation was compared in the presence of Na+ and Mg2+ ions. In the presence of 10-100 mM NaCl or in 0.1-3 mM MgCl2 but in the presence of 50 mM NaCl erythrocyte chromatin condenses in nuclei forming a structure which is characterized only by a "half-nucleosomal" periodicity of fragmentation at DNase II action. Upon higher NaCl concentration (100-400 mM) in the presence of 3 mM MgCl2 a transition from dinucleosomal fragmentation to nucleosomal fragmentation of erythrocyte chromatin in nuclei with DNase I was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Structural organization of the nucleosomal chromatin fibril under various ionic conditions]. 380 10

Acid deoxyribonuclease (EC 3.1.4.6) (DNase) from young (16 days of incubation) and old (1.5 years) chick cerebral hemispheres was purified to apparent homogeneity. Throughout the purification schedule, the behavior of "young" and "old" enzymes was similar. However, the specific activity of the purified enzyme from old brain was only one-tenth that of young enzyme. Polyacrylamide gel electrophoresis of the purified acid DNase gave a single band. Antisera against both "young" and "old" enzyme were raised and double immunodiffusion experiments revealed cross-reaction of young antigen with old antiserum and vice versa, although precipitin bands with young antigen against young antiserum and old antigen against old antiserum were more sharp. Both young and old acid DNase preparations showed an apparent molecular weight of 62,000 and many other properties like heat stability, effect of various exogenous compounds like Hg2+, Zn2+, Mg2+, etc., were also similar. The old enzyme showed slightly higher Km and decreased Vmax compared with the young enzyme. Dansylation of N-terminal amino acids and their analysis following tryptic digestion of both "young" and "old" acid DNase revealed a similar pattern. Immunotitration experiments showed that the old enzyme requires more antiserum prepared against "young" enzyme to achieve 50% inactivation, thus pointing out the presence of completely or partially inactive molecules in "old" acid DNase preparation. Circular dichroism spectra of the enzyme preparations indicated that the "old" acid DNase molecules are more rigid and have more alpha-helical structure, compared with the "young" enzyme. From these data, it is suggested that the reduction in the specific activity of old acid DNase may be, apart from other possibilities, due to conformational changes in the enzyme molecules.
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PMID:Age-dependent conformational changes in acid deoxyribonuclease of chick brain. 619 64

Chromatin was fractionated by digestion with deoxyribonuclease II and precipitation with MgCl2. The Mg2+-soluble fraction, known to be enriched in transcribed DNA sequences, was enriched also in high mobility group proteins 1 and 2 and contained almost all other acid-soluble nonhistone proteins.
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PMID:Distribution of high mobility group and other acid-soluble proteins in fractionated chromatin. 626 Jan 86

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.
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PMID:[Isolation, purification and properties of acid deoxyribonuclease from silkworm Bombyx mori eggs]. 707 75


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