Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reversible cross-linking of proteins in nuclei and DNA-depleted nuclei from Friend erythroleukemia cells was used as a probe to determine whether the protein structure was preserved following treatment with DNAase I. Interactions between histones were analyzed through cross-linking with 2-iminothiolane or dimethyl 3,3'-dithiobispropionimidate. No alterations in the interactions between intranucleosomal histone proteins resulted from digestion of the nuclear DNA. There was, however, a diminished extent of cross-linking of histone H1 to itself and to the intranucleosomal histones in DNA-depleted nuclei. The interactions of a group of nonhistone proteins with histone H3 could be monitored by cross-linking through the formation of disulfide bonds caused by oxidation of nuclei with H2O2. These interactions were not markedly affected by treatment of the nuclei with DNAase I. However, differences were observed in the extent of cross-linking of some of these proteins when cross-linking in nuclei from undifferentiated cells was compared to that in nuclei from cells which had been induced to differentiate with dimethylsulfoxide.
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PMID:Cross-linking of proteins in nuclei and DNA-depleted nuclei from Friend erythroleukemia cells. 29 21

The small genome size of mollicutes, and particularly mycoplasmas and ureaplasmas, precludes their possession of the extensive range of metabolic activities present in most other bacterial groups. Demonstrated catabolic activities appear primarily to be associated with energy generation, rather than the provision of substrates for synthetic pathways, and anabolism is largely dependent upon extracellular sources of amino acids, nucleic acid precursors and lipids. However, the pathways of energy generation in mollicutes are diverse and specialized, and may in vivo be dependent upon the presence of a single amino acid (arginine) or urea. Even in those species that utilize carbohydrates the range of substrates is restricted, and while Ac. laidlawii has both EMP and PP pathways and is able to oxidize pyruvate to acetate plus CO2, many mycoplasmas possess only a part of these activities. Such specialization and the infrequent demonstration of inducible enzyme activity in mollicutes implies adaptation to specific habitats in host species, and suggests that differences in the catabolic activities of mollicute strains may be significant in terms of their ecology and pathogenicity. The demonstrated energy-generating pathways of mollicutes produce low ATP yields. Thus, mollicute growth will generate relatively large quantities of metabolic end-products and may deplete host tissues of substrates. Arginine depletion may be of particular importance in pathogenesis and the close physical association between mollicutes and host cells will enhance the potential significance of NH4+ production from the hydrolysis of arginine and urea, and of H2O2 and superoxide formation during carbohydrate metabolism. In addition, lipid and protein catabolism may be associated with virulence where extracellular or membrane-bound enzyme activities exist. Membrane-bound DNAase and RNAase activities have also been demonstrated in mycoplasmas and Ac. laidlawii (Pollack et al., 1965) and U. urealyticum (Romano & La Licata, 1978). Many aspects of mollicute catabolism, including energy conservation in some groups, is poorly understood. Also, while substantial catabolic diversity has been demonstrated within mollicutes and new species are continually being isolated, metabolism has been studied in relatively few species, and even in these only single strains or small groups of strains have been used. In this review, therefore, an attempt to avoid generalizations concerning mollicute behaviour has been made. The lack of much basic knowledge concerning mollicute metabolism has also necessitated the widespread use of 'may be' and other equally vague terms.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Catabolism in mollicutes. 140 86

The addition of paraquat (methyl viologen) to a growing culture of Escherichia coli K-12 led within 1 hr to a 10- to 20-fold increase in the level of endonuclease IV, a DNase for apurinic/apyrimidinic sites. The induction was blocked by chloramphenicol. Increases of 3-fold or more were also seen with plumbagin, menadione, and phenazine methosulfate. H2O2 produced no more than a 2-fold increase in endonuclease IV activity. The following agents had no significant effect: streptonigrin, nitrofurantoin, tert-butyl hydroperoxide, gamma rays, 260-nm UV radiation, methyl methanesulfonate, mitomycin C, and ascorbate. Paraquat, plumbagin, menadione, and phenazine methosulfate are known to generate superoxide radical anions via redox cycling in vivo. A mutant lacking superoxide dismutase was unusually sensitive to induction by paraquat. In addition, endonuclease IV could be induced by merely growing the mutant in pure O2. The levels of endonuclease IV in uninduced or paraquat-treated cells were unaffected by mutations of oxyR, a H2O2-inducible gene that governs an oxidative-stress regulon. The results indicate that endonuclease IV is an inducible DNA-repair enzyme and that its induction can be mediated via the production of superoxide radicals.
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PMID:Endonuclease IV of Escherichia coli is induced by paraquat. 243 76

At physiologic pH values, histidine-containing nickel(II) oligopeptides reduced the flux of superoxide anion (O2-) generated in the hypoxanthine/xanthine oxidase system. The postulated involvement of the Ni(III)/Ni(II) redox couple in this apparent dismutation receives indirect support from electron-spin resonance data. These complexes also catalyzed the disproportionation of hydrogen peroxide, a process which generates active intermediates capable of hydroxylating p-nitrophenol and oxidizing uric acid to allantoin. An oxene moiety, namely [Nio]2+, is postulated as the active species in these H2O2-dependent reactions. Spectral analysis showed that monovalent, divalent and trivalent ions induced cooperative conformational changes in synthetic polydeoxynucleotides. For the nickel(II) ion, resistance to DNase-I activity clearly showed that an alternating G-C sequence is required for the observed transitions. It is concluded that the ability of nickel(II) peptide complexes to participate in active oxygen biochemistry suggests a possible role for nickel as a chemical promoter of cancer, whereas the capacity of the nickel(II) ion to induce conformational changes in DNA could, in principle, affect gene expression. Of course, the validity of both hypotheses require that the observed reactions be verified as biologically significant.
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PMID:Superoxide dismutase activity and novel reactions with hydrogen peroxide of histidine-containing nickel(II)-oligopeptide complexes and nickel(II)-induced structural changes in synthetic DNA. 248 92

The effects of oxidative stress on DNA damage and associated reactions, increased polyadenosine diphosphate-ribose polymerase (PARP) activity and decreased nicotinamide adenine dinucleotide (NAD) and adenosine triphosphate (ATP) contents, have been tested in primary cultures of porcine aortic endothelial cells. The cells were treated with 50-500 microM H2O2 for 20 min or 100 microM paraquat for 3 days or were exposed to 95% O2 for 2 and 5 days. The administration of 250-500 microM H2O2 resulted in a marked increase in PARP activity and a profound depletion of ATP and NAD. Although hyperoxia had no effect on PARP activity and reduced only slightly the ATP and NAD stores, it markedly reduced the ability of endothelial cells to increase PARP activity upon exposure to DNase. Paraquat had a similar effect. Human dermal fibroblasts were also exposed to 50-500 microM H2O2 for 20 min or 95% O2 for 5 days. Their response to H2O2 differed from that of endothelial cells by their ability to maintain the ATP content at a normal level. Fibroblasts were also insensitive to the effect of hyperoxia. These results suggest that the oxidant-related DNA damage is a function of the type of oxidative stress used and may be cell-specific.
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PMID:Differential effects of hyperoxia and hydrogen peroxide on DNA damage, polyadenosine diphosphate-ribose polymerase activity, and nicotinamide adenine dinucleotide and adenosine triphosphate contents in cultured endothelial cells and fibroblasts. 250 Apr 51

The artificial DNase activity of the 1,10-phenanthroline-cuprous ion complex [(OP)2Cu+] and H2O2 cleaves the A, B, and Z forms of DNA at different rates. The B structure, formed by most DNAs including poly(dA-dT) and poly(dA) X poly(dT), is the most susceptible to cleavage. It is completely degraded within 1 min by 40 microM 1,10-phenanthroline/4 microM Cu2+/7 mM H2O2/7 mM 3-mercaptopropionic acid. The A structure, formed by RNA X DNA hybrids such as poly(rA) X poly(dT), is cleaved in both strands roughly 10-20% as rapidly as poly(dA-dT) under comparable conditions. In contrast, the left-handed Z structure, formed by poly(dG-dC) in 3.0 M NaCl, is completely resistant to cleavage even though the same copolymer in the B structure at 15 mM NaCl is readily degraded. Poly(dA-dT) is rendered acid soluble at both salt concentrations at similar rates. The basis for the secondary structure specificity of the DNA cleavage reaction most likely resides in the requisite formation of a productive complex between (OP)2Cu+ and DNA during the course of this reaction. Previous studies have suggested that strand scission is due to oxidative destruction of the deoxyribose by hydroxyl radicals produced by the oxidation of DNA-bound Cu+ by H2O2. Apparently, the Z and A structures are unable to form a stable noncovalent complex with the same optimal geometry for cleavage as the B structure and are less susceptible to degradation. This artificial DNase activity may provide an approach to assess the formation of non-B-DNA structures in solution.
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PMID:Secondary structure specificity of the nuclease activity of the 1,10-phenanthroline-copper complex. 632 Jan 69

An alkaline endodeoxyribonuclease from rat brain has been purified to near homogeneity. The purified enzyme showed a M.Wt. of 54 Kd on SDS-PAGE and does not require metal ion for activity and thus differs from classical DNase I. No preference towards any particular form of calf thymus DNA (native, denatured, undamaged and damaged by exposure to UV, H2O2 and OsO4 and depurination) was noticed. However, with supercoiled pBR 322 plasmid DNA as substrate, higher activity was exhibited towards UV irradiated and depurinated forms. It is suggested that this DNase may be a 'housekeeping' enzyme to detect any conformational distortion in DNA and initiate excision repair.
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PMID:A broad-specific alkaline DNase from rat brain with a putative role in DNA excision repair. 822 Feb 62

Our previous results indicate that during protoplast isolation an oxidative burst occurs [A.K. Papadakis and KA Roubelakis-Angelakis (1999) Plant Physiol 127:197-205] and that suppression of totipotency is correlated with reduced antioxidant activity and low redox state [A.K. Papadakis et al. (2001b) Plant Physiol 126:434-444]. Polyamines are known to affect cell development and to act as antioxidants. Polyamines applied during isolation of tobacco (Nicotiana tabacum L.) protoplasts reduced the accumulation of O2*- but not that of H2O2. This antioxidant effect is probably due to the inhibition of microsomal membrane NADPH oxidase, which occurred in a concentration-dependent manner, with spermine exerting the highest inhibitory effect. However, during protoplast culture, polyamine oxidase activity increased severalfold in spermidine- and spermine-treated protoplasts, concomitant with H2O2 titers. A cell death program was executed in untreated protoplasts, as documented by membrane malfunction, induced DNase activity, DNA fragmentation and a positive TUNEL reaction. Protoplast cell death was prevented in protoplasts treated with putrescine, but not by treatment with spermidine or spermine, which rather had the opposite effect. The data presented suggest that PAs may be implicated in the expression of plant protoplast totipotency.
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PMID:Polyamines inhibit NADPH oxidase-mediated superoxide generation and putrescine prevents programmed cell death induced by polyamine oxidase-generated hydrogen peroxide. 1551 51

The aerobic soil bacterium Corynebacterium glutamicum ATCC 13032 has a remarkable natural resistance to hydrogen peroxide. A major player in hydrogen peroxide defense is the LysR type transcriptional regulator OxyR, homologs of which are present in a wide range of bacteria. In this study, the global transcriptional response of C. glutamicum to oxidative stress induced by hydrogen peroxide was examined using whole genome DNA microarrays, demonstrating the dynamic reaction of the regulatory networks. Deletion of oxyR resulted in an increased resistance of the C. glutamicum mutant to hydrogen peroxide. By performing DNA microarray hybridizations and RT-qPCR, differentially expressed genes were detected in the mutant. The direct control by OxyR was verified by electrophoretic mobility shift assays for 12 target regions. The results demonstrated that OxyR in C. glutamicum acts as a transcriptional repressor under non-stress conditions for a total of 23 genes. The regulated genes encode proteins related to oxidative stress response (e.g. katA), iron homeostasis (e.g. dps) and sulfur metabolism (e.g. suf cluster). Besides the regulator of the suf cluster, SufR, OxyR regulated the gene cg1695 encoding a putative transcriptional regulator, indicating the role of OxyR as a master regulator in defense against oxidative stress. Using a modified DNase footprint approach, the OxyR-binding sites in five target promoter regions, katA, cydA, hemH, dps and cg1292, were localized and in each upstream region at least two overlapping binding sites were found. The DNA regions protected by the OxyR protein are about 56bp in length and do not have evident sequence similarities. Still, by giving an insight in the H2O2 stimulon and extending the OxyR regulon this study considerably contributes to the understanding of the response of C. glutamicum to hydrogen peroxide-mediated oxidative stress.
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PMID:Transcriptional response of Corynebacterium glutamicum ATCC 13032 to hydrogen peroxide stress and characterization of the OxyR regulon. 2510 7

Fermented foods are known to be rich source of valuable nutrients and probiotics. Previously, our study reported the isolation and characterization of eight potential probiotic strains from traditional mango brine pickle, which has been conventionally consumed for ages in raw form in Southern India. The present study reports on the safety assessment of these strains for the selection of prospective probiotic candidates. Hydrogen peroxide production, histidine decarboxylase activity (production of histamine), DNase activity, and presence of the virulence factor genes (assessed by PCR) were carried out to evaluate its safety. Bacillus licheniformis KT921419 and B. methylotrophicus KT921422 was found to show no adverse safety characteristics. These two strains were further assessed for their ability to survive in the native substrate (mango brine pickle) as single and mixed inoculums. Above strains maintained significant viability in mango brine pickle for a period of 6 months during storage at the room temperature. Results clearly proved the safety and stability of two of the potential probiotic strains, which can be further utilized in food applications under harsh conditions of high salt, low pH, and room temperature making these strains unique.
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PMID:Safety and Stability Assessment of Potential Probiotic Strains from Fermented Mango Brine Pickle. 3170 7


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