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)

Methylation of a calf thymus DNA substrate by dimethyl sulphate (DMS) leads to an inhibition of deoxyribonuclease II activity which is gradually lost with time. The extent of this initial inhibition is linearly related to the amount of methylated products in DNA and quantitatively similar effects were found when the enzyme was used under either acid or neutral conditions. Deoxyribonuclease II was shown to produce 3'-phosphate termini under both acid and neutral conditions and thus, irrespective of the ionic conditions for the action of this enzyme in vivo the effects demonstrated here are of potential significance. Local denaturation of the methylated DNA may be partly responsible for these inhibitory effects but it is likely that the methyl purines also play a more direct role.
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PMID:Resistance of alkylated DNA to degradation by deoxyribonuclease II at neutral and acid pH. 0 18

The concentration of free phosphate groups is measured in rat liver chromatin after DNase II digestion using polylysine titration. The unsheared chromatin completely precipitates at lysine/DNA phosphate ratios of 0.5 to 0.6. Digestion of the chromatin reduces the lysine/DNA phosphate ratio of complete precipitation by about 0.2 units suggesting the removal of free phosphate groups. The two chromatin fractions: MgC12 insoluble (template-inactive) and Mg12 soluble (template-active) chromatins precipitate at about the same lysine/DNA phosphate ratio. Some 15% of the MgC12 soluble chromatin remains in solution at any polylysine concentration. The removal of histone H 1 FROM THE MgC12 insoluble chromatin increases the lysine/DNA phosphate ratio by about 0.2 units suggesting that 20% of the DNA phosphate groups in nucleosomes are masked by histone H 1.
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PMID:Polylysine titration of rat liver chromatin fractions after DNase II digestion. 86 91

1. The response to thermal acclimation of five key rate-limiting enzymes of intermediary metabolism and of six degradative enzymes was measured in tissue extracts of adult Drosophila melanogaster which had been acclimated for 4 days to 15, 25 or 30 degrees C. 2. Three enzymes of intermediary metabolism (HK, alpha-GPDH and CO) showed positive thermal compensation, which is the type of response characteristic of the enzymes involved in energy metabolism in vertebrate ectotherms. 3. The data obtained for CS and G6PDH showed no evidence for increased activity of TCA cycle nor of the pentose phosphate pathway upon cold acclimation in D. melanogaster. 4. Two degradative enzymes, ADH and non-specific esterase, showed inverse thermal compensation which is the type of response characteristic of degradative enzymes in vertebrate ectotherms. 5. In contrast to the situation in vertebrate ectotherms, catalase and the three lysosomal enzymes assayed (APH, acid DNase and acid RNase) displayed positive rather than inverse compensation. 6. The results presented here extend the data on the range of D. melanogaster enzymes which show compensation upon thermal acclimation and on the type of acclimation response which occurs.
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PMID:The effect of acclimation temperature on enzyme activity in Drosophila melanogaster. 165 Dec 3

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

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

A method for analyzing free nucleotides in the epidermis of the guinea pig is presented. Free nucleotides were extracted by using a methylalethanol mixture, and the analysis was carried out by high-pressure liquid chromatography on a column of Lichrosorb-NH2 with a single buffer of potassium phosphate. The concentration of total free nucleotides in the epidermis is about 4 times greater than that in the liver, kidney, spleen, or intestinal epithelium.l The free nucleotide level is markedly elevated in the hyperkeratotic epidermis induced by n-hexadecane. The alternation of free nucleotides in hyperkeratotic epidermis is discussed in relation to nucleic acid content, DNase, disc-electrophoretic properties of DNase, and salvage pathway enzymatic activity. Significant increases in the enzyme activity of the salvage pathway and in neutral DNase were observed in the hyperkeratotic stage. However, the DNA content and acid DNase activity were decreased. It is suggested that the pool size of free nucleotides in the epidermis is affected by the salvage enzyme system.
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PMID:High-pressure liquid chromatography of free nucleotide patterns in normal and abnormal keratinocytes. 616 23

Musoca from bovine small intestine was homogenized in Krebs-Ringer phosphate buffer, pH 7.8 the homogenate centrifuged at 16300 X g, and the supernatant solution filtered through cheesecloth to remove lipid material. The filtrate was centrifuged at 105000 X g and the supernatant solution chromatographed on DEAE-cellulose. The major peak of DNase II activity, eluted with 20 mM phosphate - 10 mM EDTA buffer, pH 7.8, was purified further by ion-exchange chromatography on CM-cellulose and gel filtration on Sephadex G-100. The enzyme was purified 78-fold in 13% yield. Evidence was adduced to indicate that the second minor peak of DNase II activity, eluted from the DEAE-cellulose by a potassium chloride gradient in the 20 mM phosphate - 10 mM EDTA buffer, was an artifact arising from the presence of significant amounts of DNA in the 105000 X g supernatant. The enzyme degraded DNA endonucleolytically to 3'-PO4, 5'-OH oligonucleotides and is similar in its properties to DNase II from other tissues.
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PMID:Isolation of deoxyribonuclease II from bovine intestinal mucosa. 625 55

Cellular nuclease activity is a potential barrier to the successful delivery of foreign genes to mammalian cells. We tested the hypothesis that transfection in the presence of a specific DNase inhibitor can enhance the expression of foreign gene products. We have used DMI-2, a polyketide metabolite of Streptomyces sp. strain 560 to enhance the expression of bacterial chloramphenicol acetyltransferase (CAT) in the human lung adenocarcinoma cell line H441. DMI-2 has been shown previously to inhibit porcine DNase II, an acid pH nuclease contained in the endosomal/lysosomal compartment. Transfection of H441 cells in the presence of 0.1-1 microgram/ml DMI-2 caused: (1) 10-fold enhancement of CAT activity when the bacterial plasmid was complexed with either surfactant protein A-poly-lysine or transferrin-poly-lysine; (2) 1.5- to two-fold enhancement of CAT activity in cells exposed to lipofectin-DNA complexes: (3) no effect on transfection via calcium phosphate co-precipitation. DMI-2 alone showed no inherent transfection activity. In experiments using SP-A-poly-lysine and plasmid containing the beta-galactosidase reporter gene, DMI-2 increased the number of transfected cells. Methanolysis products of DMI-2 did not inhibit DNase II and did not enhance transfection efficiency. Taken together, the data support the hypothesis that nuclease action is a significant barrier to expression of foreign genes and inhibition of specific nucleases may facilitate transfection.
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PMID:Enhanced reporter gene expression in cells transfected in the presence of DMI-2, an acid nuclease inhibitor. 993 Mar 26

The 134 amino acid DNase domain of colicin E9 contains a zinc-finger-like HNH motif that binds divalent transition metal ions. We have used 1D 1H and 2D 1H-15N NMR methods to characterise the binding of Co2+, Ni2+ and Zn2+ to this protein. Data for the Co2+-substituted and Ni2+-substituted proteins show that the metal ion is coordinated by three histidine residues; and the NMR characteristics of the Ni2+-substituted protein show that two of the histidines are coordinated through their N(epsilon2) atoms and one via its N(delta1). Furthermore, the NMR spectrum of the Ni2+-substituted protein is perturbed by the presence of phosphate, consistent with an X-ray structure showing that phosphate is coordinated to bound Ni2+, and by a change in pH, consistent with an ionisable group at the metal centre with a pKa of 7.9. Binding of an inhibitor protein to the DNase does not perturb the resonances of the metal site, suggesting there is no substantial conformation change of the DNase HNH motif on inhibitor binding. 1H-15N NMR data for the Zn2+-substituted DNase show that this protein, like the metal-free DNase, exists as two conformers with different 1H-15N correlation NMR spectra, and that the binding of Zn2+ does not significantly perturb the spectra, and hence structures, of these conformers beyond the HNH motif region.
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PMID:NMR studies of metal ion binding to the Zn-finger-like HNH motif of colicin E9. 1083 Aug 90


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