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)

The characteristics of an in vitro polyuridylic acid dependent amino acid incorporating system prepared from germinating macroconidia of Microsporum canis are described. The incorporation of 14C-phenylalanine into polyphenylalanine is dependent on S-30 extract, adenosine triphosphate, magnesium ions and polyuridylic acid. Incorporation is slightly enhanced by yeast transfer ribonucleic acid and pyruvate kinase. The system is highly sensitive to ribonuclease, puromycin and miconazole (an antifungal agent), moderately sensitive to sodium fluoride and much less sensitive to phenethylalcohol, cycloheximide, chloramphenicol and deoxyribonuclease. Cell-free extract from ungerminated conidia has less capacity to synthesize the protein and during germination a marked increase in the protein synthetic activity is observed. The results from experiments wherein ribosomes and S-100 fraction from germinated and ungerminated spores are unterchanged, revealed that the defect in the extract from the ungerminated spore is in the ribosomes.
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PMID:Studies on the macroconidia of Microsporum canis. Characteristics of in vitro amino acid incorporating system. 42

A general mechanism by which proteins locate their target sites within large domains of DNA is a one-dimensional facilitated diffusion process in which the protein scans DNA in a nonspecifically bound state. An electrostatic contribution to this type of mechanism has been previously established. This study was designed to question whether other characteristics of a protein's structure might contribute to the scanning mechanism of target site location. In this regard, T4 endonuclease V was shown to establish an ionic strength dependent monomer-dimer equilibrium in solution. A protein dimer interaction site was postulated to exist along a putative alpha-helix containing amino acid residues 54-62. The conservative substitutions of Phe-60----Leu-60 and Phe-59, Phe-60----Leu-59, Leu-60 resulted in mutant enzymes which remained in the monomeric state independent of the ionic strength of the solution. The target site location mechanism of these mutants has also been altered. Under conditions where wild-type endonuclease V processively scans nontarget DNA, the target location mechanism of the monomeric mutant proteins was shifted toward a less processive search. This decrease in the processivity of the mutants was especially surprising because the nontarget DNA binding affinity was found to be significantly increased. Thus, an additional component of the endonuclease V DNA scanning mechanism appears to be the formation of a stable endonuclease V dimer complex.
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PMID:Mutations in endonuclease V that affect both protein-protein association and target site location. 188 26

Previous structure/function analyses of the DNA repair enzyme, T4 endonuclease V, have suggested that the extreme carboxyl portion of the enzyme is associated with pyrimidine dimer-specific binding (Recinos and Lloyd, and Stump and Lloyd, Biochemistry 27:1832-1838 and 1839-1843, 1988, respectively). Within the final 11 amino acids there are 5 aromatic, 2 basic, and no acidic residues and it has been proposed that these residues stack with and electrostatically interact with the kinked DNA at the site of a pyrimidine dimer. The role of the tyrosine residue at position 129 has been investigated by oligonucleotide site-directed mutagenesis in which the codon for Tyr-129 has been altered to reflect conservative changes of Trp and Phe and more dramatic changes of Ser, a stop codon, deletion of the codon or introduction of a frameshift. Both changes to the aromatic amino acids resulted in proteins which accumulated well in E. coli and not only significantly enhanced the UV survival of repair-deficient cells but also complemented a defective denV gene within UV-irradiated T4 phage. Partially purified preparations of the Tyr-129----Trp and Tyr-129----Phe mutants were assayed for their ability to processively incise UV-irradiated plasmid DNA (a nicking reaction carried out at low 25 mM salt concentrations). The mutant enzymes Tyr-129----Phe and Tyr-129----Trp displayed a 1000% and 500% enhanced specific nicking activity, respectively. These reactions were also shown to be completely processive. Assays performed at higher (100 mM) salt concentrations reduced the specific activities of the mutant enzymes approximately to that of wild type for the Tyr-129----Phe mutant and to 20% that of wild type for the Tyr-129----Trp mutant.
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PMID:Site-directed mutagenesis of the T4 endonuclease V gene: mutations which enhance enzyme specific activity at low salt concentrations. 269 26

Cell-free peptide synthesis by extracts from vegetative cells and spores of Bacillus subtilis was analyzed and compared. The initial rate of phenylalanine incorporation in a polyuridylate-directed system was found to be in a similar range for the two extracts. However, spore extracts frequently incorporated less total phenylalanine as did the vegetative cell system. Optimal conditions for amino acid incorporation by spore extracts were found to be similar to those of vegetative cell extracts. Polyphenylalanine synthesis was stimulated by preincubation of both extracts prior to the addition of polyuridylic acid (poly U) and labeled phenylalanine. Both systems showed a dependence on an energy-generating system and were inhibited by chloramphenicol and puromycin. Ribonuclease, but not deoxyribonuclease, inhibited the reaction significantly. The presence of methionine transfer ribonucleic acid (tRNA(F)) and methionyl-tRNA(F) transformylase was demonstrated in spore extracts. An analysis of several aminoacyl-tRNAs in spores revealed that the relative amounts of these tRNAs were similar to those found in vegetative cells. Only lysine tRNA was found to be present in relatively greater amounts in spores. These results indicate that dormant spores of B. subtilis contain the machinery for the translation of genetic information.
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PMID:Peptide synthesis by extracts from Bacillus subtilis spores. 498 76

Cell walls isolated from competent streptococci (group H strain Challis) were shown to bind more homologous and heterologous deoxyribonucleic acid (DNA) than noncompetent walls. Heat- and alkali-denatured DNA was not bound by either wall preparation. Pretreatment of cell walls with cetyltrimethylammonium bromide sharply increased the binding of DNA but did not increase transformation of whole cells. Pretreatment of the walls with either sodium dodecylsulfate, deoxyribonuclease and ribonuclease, or with crude competence-provoking factor did not affect the binding of DNA. Antiserum prepared against whole competent cells completely blocked transformation and also inhibited DNA binding to competent cell walls. Adsorption of this antiserum with competent Challis cells removed its blocking action for both binding and transformation. Pretreatment of walls with trypsin and Pronase destroyed their ability to bind DNA. Trypsin treatment also blocked transformation in whole cells. The transforming activity of DNA bound to cell walls was found to be protected from deoxyribonuclease action. Significant differences were observed in the arginine, proline, and phenylalanine content of competent and noncompetent walls. With few exceptions, the amino acids released from competent cell walls by trypsin were several-fold greater than from noncompetent walls. The results indicate that (i) two binding sites exist, one in competent cells only and essential for subsequent transformation, and a second, present in all cells, which is not involved in transformation; (ii) both sites are protein in nature; (iii) the transformation site is blocked by antibody; and (iv) the competent cell wall possesses tryptic-sensitive protein not present in the noncompetent wall.
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PMID:Binding of deoxyribonucleic acid by cell walls of transformable and nontransformable streptococci. 510 95

Shiio, Tsuru (Washington State University, Pullman), and Bruce A. McFadden. Cell-free amino acid-incorporating system from Pseudomonas indigofera. J. Bacteriol. 90:978-983. 1965.-A cell-free preparation from Pseudomonas indigofera incorporated C(14)-phenylalanine and C(14)-leucine into a product which was insoluble in hot trichloroacetic acid. The phenylalanine incorporation process, which had a temperature optimum of 30 C and a pH optimum of 7.6, had many characteristics of protein synthesis. The process depended upon both "ribosomes" and supernatant fraction from centrifugation at 105,000 x g. Incorporation required adenosine triphosphate, apparently depended upon guanosine triphosphate, and was inhibited by chloramphenicol, puromycin, actinomycin, ribonuclease, and deoxyribonuclease. Leucine incorporation was also studied and had many similar characteristics. C(14)-phenylalanine uptake was stimulated by sRNA or polyuridylic acid, and together these substances had a synergistic effect upon stimulation. The incorporation of C(14)-phenylalanine into a product which was precipitated by antiserum to crystalline isocitrate lyase was also observed.
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PMID:Cell-free amino acid-incorporating system from Pseudomonas indigofera. 584 10

Ochratoxin A (OTA) a chlorodihydro-isocoumarin linked through an amide bond to phenylalanine, is a mycotoxin found as a contaminant in foodstuffs and shown to be nephrotoxic, teratogenic, immunosuppressive, genotoxic, mutagenic and carcinogenic in rodents. Ochratoxin A is known to induce teratogenic effects in neonates (rats and mice) exposed in utero, characterised by microcephaly and modification of the brain levels of free amino acids. Since OTA has been found to accumulate in the brain according to the duration of exposure to doses in the range of natural contamination of feedstuffs, experiments were designed to determine more precisely the structural target of OTA in the brain. After intracerebral injection, OTA (403 ng/10 microl) was not found in the following parts of the brain: the frontal cortex (FC), striatum (ST), ventral mesencephalon (VM) and the cerebellum (CB) in contrast to the rest of the brain, probably due to the detection limit of 0.1 ng/g of tissue. However lactate dehydrogenase (LDH) was increased in extracellular space in the VM to a greater extent than in the rest of the brain, indicating that this structure could be one of the targets of OTA in the brain. Contents of free amino acids were morever similarly modified in the VM and in the rest of the brain. Male rats were given OTA (289 microg/kg per 24 h) by gastric intubation for 8 days and the main brain structures analysed for OTA content and cytotoxicity. OTA was found in the following structures in decreasing order: rest of the brain (50.3%), cerebellum (34.4%), VM (5.1%), striatum (3.3%) and hippocampus (2.9%) of the total OTA amount found in the brain, which represents 0.022% to 0.028% of the given dose. Interestingly cytotoxicity as measured by lactate dehydrogenase (LDH) release in the extracellular space was much more pronounced in the VM, hippocampus, and striatum than in the cerebellum, whereas no cytotoxicity was observed in the rest of the brain. Similarly deoxyribonuclease (DNase) activity in relation to possible necrotic cells was increased in the VM and cerebellum. Altogether these results designated the ventral mesencephalon, hippocampus, striatum and cerebellum as the main OTA-targets in the brain of adult rats and excluded the rest of the brain.
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PMID:Regional selectivity to ochratoxin A, distribution and cytotoxicity in rat brain. 985 82

Sperm were incubated for up to 9 days in the presence or absence of exogenous hydrogen peroxide, phenylalanine, catalase and aurintricarboxylic acid to assess the influence of reactive oxygen species and inhibition of deoxyribonucleases on sperm chromatin stability. The assessment of sperm DNA susceptibility to in situ acid denaturation by the sperm chromatin structure assay did not detect any difference in chromatin stability between sperm incubated for 9 days under aerobic and anaerobic conditions in a diluent called 14G. Exposure to exogenous hydrogen peroxide under both aerobic and anaerobic conditions and to phenylalanine under aerobic conditions (which produces hydrogen peroxide by a reaction catalysed by the aromatic amino acid oxidase present in sperm) was detrimental to sperm chromatin stability, increasing its DNA susceptibility to in situ acid denaturation over the incubation time. This effect was eliminated if catalase was present in the diluent. Inclusion of the general deoxyribonuclease inhibitor aurintricarboxylic acid in the diluent severely decreased sperm chromatin stability under both aerobic and anaerobic conditions. Aurintricarboxylic acid was mildly cytotoxic, as revealed by viability assessment, under aerobic, but not under anaerobic, incubation conditions. Exogenous hydrogen peroxide, either directly added to the diluent or generated through the enzymatic oxidation of phenylalanine, was detrimental to sperm motility and the integrity of the plasma membrane.
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PMID:Changes in susceptibility of bovine sperm to in situ DNA denaturation during prolonged incubation at ambient temperature under conditions of exposure to reactive oxygen species and nuclease inhibitor. 1145 Oct 15

Graphene oxide (GO) is an important type of 2D nanomaterial and widely used in biomedicine, sensors, photocatalysis and electronic materials. With the extensive exposure of GO, its biological effect is debatable. In this study, we found a novel biological effect of GO, ie, suppression of deoxyribonuclease (DNase). GO inhibited DNA degradation when DNA or the DNA/RNA mixture was exposed to DNase. Moreover, GO suppressed nuclear fragmentation when the nuclei were treated with DNase. Interestingly, GO neither interacted with DNA nor influenced the interaction between DNase and DNA. Further investigation revealed that GO had a strong activity of adsorbing l-phenylalanine and l-histidine, key amino acid residues in the active site of DNase. These results suggest that GO could suppress the activity of DNase by interaction with the active site of DNase, and have an impact on DNase-related cellular processes (eg, apoptosis), implying its potential application in treating diseases associated with disorderly DNase function.
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PMID:Graphene oxide severely inhibits DNase activity. 3008 84