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

Treatment of growing cultures of Mycobacterium smegmatis with alkylating agents (methyl methanesulphonate, ethyl methanesulphonate, nitrogen mustard, or mitomycin C) or with ultraviolet light resulted in enhanced specific activities of a DNA polymerase and of an ATP-dependent deoxyribonuclease. Similar results had previously been obtained with hydroxyurea and with iron limitation. The three of these treatments which were tested (methyl methanesulphonate, mitomycin C and hydroxyurea) produced strand breaks or alkali-labile regions in the DNA of this organism. The increased enzyme activities could be prevented by simultaneous treatment with inhibitors of protein synthesis. In contrast, treatment of the cultures with intercalating agents (ethidium bromide, acridine orange, or proflavine), 5-fluorouracil, caffeine, or nalidixic acid, inhibited DNA synthesis without increasing the enzyme activities. These treatments did not produce strand breaks in the DNA of this organism. The results support the hypothesis that, in M. smegmatis, damage to DNA induces increased synthesis of enzymes associated with DNA repair.
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PMID:Increased DNA polymerase and ATP-dependent deoxyribonuclease activities following DNA damages in mycobacterium smegmatis. 84 85

An endodeoxyribonuclease from HeLa cells acting on apurinic/apyrimidinic (AP) sites has been purified to apparent homogeneity as judged by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. The presence of Triton X-100 was necessary throughout the purification for stabilization and stimulation of activity. The endonuclease has an apparent native molecular weight of 32,000 determined by molecular sieving and an apparent subunit molecular weight of 41,000 as judged by its electrophoretic mobility in SDS-polyacrylamide gels. The activity has an absolute requirement for Mg2+ or Mn2+ and a broad pH optimum between 6.7 and 9.0 with maximal activity near pH 7.5. The enzyme has no detectable exonuclease activity, nor any endonuclease activity on untreated duplex or single-stranded DNA. It is inhibited by adenine, hypoxanthine, adenosine, AMP, ADP-ribose, and NAD+, but it is unaffected by caffeine, the pyrimidine bases, ADP, ATP, or NADH. The use of a variety of damaged DNA substrates provided no indication that the enzyme acts on other than AP sites. The enzyme appears to cleave AP DNA so as to leave deoxyribose-5-phosphate at the 5' terminus and a 3'-OH at the 3' terminus; it also removes deoxyribose-5-phosphate from AP DNA which has deoxyribose at the 3' terminus. Specific antibody has been produced in rabbits which interacts only with a 41,000-dalton protein present in the purified enzyme (presumably the enzyme itself), as well as with partially purified AP endonuclease fractions from human placenta and fibroblasts.
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PMID:Purification and characterization of an apurinic/apyrimidinic endonuclease from HeLa cells. 625 65

Chemoprevention is suitable for patients who are at high risk of development of numerous or invasive nonmelanoma skin cancers (NMSCs). Various substances have been studied as potential chemopreventive agents for NMSC. Oral retinoids have been proven to be effective in the suppression of new squamous cell carcinoma (SCC) development. Patients need to stay on oral retinoids as long as chemoprevention is needed with careful monitoring of the dose and side effects. Topical retinoids are not effective in prevention of NMSC. In organ transplant patients with aggressive or numerous skin cancers, decrease in the immunosuppression or switch to mammalian target of rapamycin inhibitors (sirolimus or everolimus) can be considered. Field therapy for areas of severe actinic damage with photodynamic therapy, imiquimod, 5-fluorouracil, ingenol mebutate, or diclofenac sodium may theoretically decrease the risk of SCC through treatment of precancerous changes. However, there is limited data regarding efficacy of these agents in chemoprevention of NMSC. Epidemiologic studies suggest a protective role for nonsteroidal anti-inflammatory agents in development of NMSC. Limited data support chemopreventive effect of difluoromethylornithine and T4 endonuclease V for actinic keratoses and basal cell carcinoma. Amongst dietary factors, low-fat diet, limonene from citrus fruit peel, and caffeine may protect against NMSC.
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PMID:Chemoprevention of nonmelanoma skin cancer. 2553 38