Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A deoxyribonuclease has been purified more than 2000-fold from the green algae, Chlamydomonas reinhardii. The enzyme is most active on denatured DNA. Optimum activity is at pH 8.5, in 80 mM Tris-HCl buffer and 2 mM CaCl2. Other divalent cations can replace Ca2+ with varying lower efficiency. EDTA and inorganic phosphate are strongly inhibitory, while ATP and high concentrations of 2-mercaptoethanol are slightly inhibitory. The molecular weight is approximately 35 000, the Stokes radius is 2.7 nm, and the sedimentation coefficient 2.8 S. It is a single polypeptide chain, and the frictional ratio of 1.27 suggests it is only slightly asymetrical. The isoelectric point is 9.5. This enzyme has been termed exonuclease 1.
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PMID:A deoxyribonuclease from Chlamydomonas reinhardii. 1. Purification and properties. 1 43

The ability of different metal ions to promote transformation of Pseudomonas aeruginosa by deoxyribonucleic acid of the plasmid RP1 was examined. CaCl2, MgCl2, and MnCl2 were found to promote such transformation, although at different frequencies and with the optimum response at different concentrations. Only MgCl2 promoted transfection of P. aeruginosa by the linear deoxyribonucleic acid of phage F116. CaCl2 was demonstrated to allow adsorption and entry into the cell of F116 deoxyribonucleic acid such that it became resistant to exogenous deoxyribonuclease, but phage production occurred only when MgCl2 was provided. Inactivation of linear phage deoxyribonucleic acid taken up in the absence of MgCl2 was observed. The transfection frequencies at various concentrations of MgCl2 were compared, and the optimum response occurred at the concentration which promoted the highest frequency of transformation by RP1 deoxyribonucleic acid.
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PMID:Transformation and transfection of Pseudomonas aeruginosa: effects of metal ions. 11 40

Plasmolysed cells of Escherichia coli N212 (uvr A recA) acquired ultraviolet resistance when the cells were exposed to high concentrations of T4 endonuclease V. With increasing concentrations of T4 enzyme, survivals of plasmolysed cells after ultraviolet irradiation increased while colony-forming ability of unirradiated plasmolysed cells was not significantly affected by the enzyme treatment. Under appropriate conditions more than 200 fold increase in survivals was observed. When plasmolysed cells were treated with a pre-heated enzyme preparation or enzyme fractions derived from T4v1 (endonuclease V-deficient mutant)-infected cells, only little or no reactivation took place. Permeabilization of cells prior to the enzyme treatment was essential for the effective reactivation. Treatment of intact cells with the T4 enzyme did not cause any reactivation. Cells treated with 20 mM EGTA or 50 mM CaCl2 in cold were reactivated to certain extents by the enzyme, but the extents of the reactivation were far less compared to those of plasmolysed cells. Plasmolysed cells of strains carrying a mutation in one of uvrA, uvrB and uvrC genes were reactivated by introduction of T4 endonuclease V, as was the uvrA recA double mutant. UvrD mutants were also reactivated, but rather slightly. However, wild type strain as well as strains having a mutation in recA or polA gene were not reactivated. From these results it was suggested that T4 endonuclease V, taken up into permeable cells, can function in vivo to replace defective functions, which are controlled by the uvr genes. The conditions established in the present study may be used for introduction of other proteins into viable bacterial cells.
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PMID:Introduction of an active enzyme into permeable cells of Escherichia coli: acquisition of ultraviolet light resistance by uvr mutants on introduction of T4 endonuclease V. 37 39

Conditions were characterized for maximizing the uptake of exogenous mammalian cell DNA by hypoxanthine-guanine phosphoribosyltransferase-deficient Chinese hamster lung cells. Recipient cell cultures in an exponential growth phase were found to be more competent in taking up DNA than stationary cultures. Polyornithine enhanced the uptake of exogenous DNA more reproducibly and to a greater extent than did any of the other facilitators tested (DEAE-dextran, CaCl2, latex spheres, spermine, polylysine and polyarginine). Maximal DNA incorporation occurred when polyornithine and DNA were mixed together prior to inoculation. About 25-30% of the DNA inoculum became deoxyribonuclease-resistant in a typical experiment utilizing polyornithine as the facilitator. Both homologous and heterologous exogenous DNAs rapidly became associated with recipient cell nuclei: approximately 95% of the deoxyribonuclease-resistant donor DNA was nuclear-associated 15 min after inoculation.
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PMID:Optimal conditions for uptake of exogenous DNA by Chinese hamster lung cells deficient in hypoxanthine-guanine phosphoribosyltransferase. 116 8

Transformation of pBR322 DNA into Shigella occurred at a low frequency. The efficiency of transformation was highest in S. dysenteriae 1 and lowest in S. flexneri. Treatment of cells with CaCl2 for a prolonged period (24h) increased the efficiency of transformation in all strains, except in S. flexneri, where transformation efficiency could not be improved by a variety of manipulations. Transformation efficiency did not increase in any of the strains when transformation was carried out with plasmid DNA obtained from a transformant (homologous transformation), suggesting the absence of a strong restriction-modification system. Extracellular deoxyribonuclease (DNase) levels were low in all the strains tested, but the levels of endogenous DNAse, released after CaCl2 treatment or sonication of the cells, were high. Washing the cells with a solution of CaCl2 did not enhance transformation, suggesting that endogenous DNase could be a significant factor affecting transformation efficiency in species of Shigella.
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PMID:Studies on transformation in Shigella. 239 Jul 45

An endodeoxyribonuclease has been purified to near homogeneity from rat small intestinal mucosa by a procedure involving Con A-Sepharose affinity chromatography. During the initial steps of purification, the presence of 5 mM CaCl2 was essential for stability of the enzyme activity. The enzyme has a molecular weight of 32 000 and an isoelectric point of 4.7. NaCl, sulfhydryl reagents, and iodoacetate strongly inhibited the reaction, but tRNA did not. The enzyme required divalent cations for activity and had a pH optimum of pH 6.2 with Co2+ and pH 7.7 with Mn2+. In both optimum conditions, the enzyme hydrolyzed native DNA more rapidly than denatured DNA, and the average chain lengths of limit digestion products of native and denatured DNA were 8 and 10, respectively, at pH 6.2 and 9 and 11, respectively, at pH 7.7. The enzyme activity to produce acid-soluble fractions from linear DNA substrate was similar in the two optimum conditions, but the activity to nick double-stranded, superhelical circular DNA substrate was significantly higher at pH 6.2 than at pH 7.7. The endonuclease formed single-strand breaks making 5'-phosphoryl and 3'-hydroxyl termini, and deoxythymidine was present at the 5' termini with a frequency of about 50% in both optimum conditions. Bovine pancreatic DNase I antibody and G-action inhibited the enzyme activity. Thus this endonuclease is classified as a DNase I.
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PMID:Purification and properties of a neutral endodeoxyribonuclease from rat small intestinal mucosa. 707 91