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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the heterogeneity of Mycoplasma ovipneumoniae, sixty isolates from three sheep on each of twenty farms were examined by restriction endonuclease analysis (REA) and SDS-PAGE. All were found to be different except for three isolates obtained from one farm. The protein and REA patterns of individual isolates were both highly reproducible and remained unchanged following long term passage (approximately 400 generations) in vitro. No plasmids were detected in the twelve strains which were examined and when two isolates were co-cultured in vitro, no genetic interchange, as judged by changes in REA patterns were detected. Since the heterogeneity of M. ovipneumoniae when examined by SDS-PAGE is too great to allow groups to be recognised, it could be advantageous for this purpose if only surface proteins were compared. As a preliminary step to this end we have identified several surface proteins of M. ovipneumoniae and found that some are common to all strains, one surface protein was shared by five of the eight strains examined and another was unique to one strain. This approach has the potential to allow the recognition of grouping of M. ovipneumoniae isolates.
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PMID:A study of the heterogeneity of isolates of Mycoplasma ovipneumoniae from sheep in New Zealand. 177 56

The heterogeneity of Mycoplasma ovipneumoniae isolates from the lungs of sheep with chronic non-progressive pneumonia (CNP) from the same flock raised the possibility that multiple isolates derived from one lung were not all identical. To test this hypothesis, thirty isolates were obtained from each of six pneumonic sheep lungs at slaughter. Four lungs had relatively severe lesions and from each of these, three or four strains of M. ovipneumonia, distinguishable by REA and in most cases by SDS-PAGE, were detected. From the lungs of each of two sheep with mild lesions, two strains of M. ovipneumoniae were detected. Four isolates from one lung were further examined by restriction endonuclease analysis (REA) using many restriction endonucleases. Those which differed with EcoRI also differed when other restriction endonucleases were used. However, partial digests occurred mainly with those restriction endonucleases which recognise cytosine-rich sequences. The presence of multiple strains of one species of microorganism in individual lesions is an unusual concept which may not be limited to one disease or to one host.
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PMID:The isolation of multiple strains of Mycoplasma ovipneumoniae from individual pneumonic sheep lungs. 177 57

An ATP-dependent DNA aggregating activity was purified from rat liver by DEAE-cellulose, phosphocellulose, and novobiocin-Sepharose column chromatography. The protein aggregated superhelical, relaxed, single-, or double-stranded DNA in a divalent cation- and ATP-dependent reaction. The DNA aggregating activity was detected by retardation of a DNA-protein complex at the origin on a 1% agarose gel. The protein appeared to exist in solution as a monomer of molecular weight 66,000, and had no DNA polymerase, topoisomerase, recombinase, or ligase activity. The DNA aggregating activity was inhibited by 10 mM nalidixic acid or 1 mM novobiocin but not by 20 mM N-ethylmaleimide or camptothecin. Adenylyl(beta,gamma-methylene)-diphosphonate, adenylyl-imidodiphosphate, or adenosine-5'-O(3-thiotriphosphate) did not substitute for ATP whereas CTP, dTTP, or the ATP analog adenylyl(alpha,beta-methylene)-diphosphonate could replace ATP. The aggregated DNA was only partially dissociated by restriction endonuclease digestion but was completely dissociated by deproteinization with SDS, proteinase K, or chloroform/octanol extraction. On the basis of the molecular weight, thermostability, antigenic property, and amino acid sequence homology in the first 12 positions, we conclude that the rat liver protein is serum albumin and that the ATP-dependent DNA aggregation is a novel function of rat serum albumin.
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PMID:ATP-dependent DNA aggregation is a novel function of rat serum albumin. 189 9

We have detected the in situ activities of DNA glycosylase, endonuclease, exonuclease, DNA polymerase, and DNA ligase using a novel polyacrylamide activity gel electrophoresis procedure. DNA metabolizing enzymes were resolved through either native or SDS-polyacrylamide gels containing defined 32P-labeled oligonucleotides annealed to M13 DNA. After electrophoresis, these enzymes catalyzed in situ reactions and their [32P]DNA products were resolved from the gel by a second dimension of electrophoresis through a denaturing DNA sequencing gel. Detection of modified (degraded or elongated) oligonucleotide chains was used to locate various enzyme activities. The catalytic and physical properties of Novikoff hepatoma DNA polymerase beta were found to be similar under both in vitro and in situ conditions. With 3'-terminally matched and mismatched [32P]DNA substrates in the same activity gel, DNA polymerase and/or 3' to 5' exonuclease activities of Escherichia coli DNA polymerase I (large fragment), DNA polymerase III (holoenzyme), and exonuclease III were detected and characterized. In addition, use of matched and mismatched DNA primers permitted the uncoupling of mismatch excision and chain extension steps. Activities first detected in nondenaturing activity gels as either multifunctional or multimeric enzymes were also identified in denaturing activity gels, and assignment of activities to specific polypeptides suggested subunit composition. Furthermore, DNA substrates cast within polyacrylamide gels were successfully modified by the exogenous enzymes polynucleotide kinase and alkaline phosphatase before and after in situ detection of E. coli DNA ligase activity, respectively. Several restriction endonucleases and the tripeptide (Lys-Trp-Lys), which acts as an apurinic/apyrimidinic endonuclease, were able to diffuse into gels and modify DNA. This ability to create intermediate substrates within activity gels could prove extremely useful in delineating the steps of DNA replication and repair pathways.
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PMID:Characterization of DNA metabolizing enzymes in situ following polyacrylamide gel electrophoresis. 200 53

Two lytic bacteriophages of Bacillus subtilis BF7658 were isolated. Their morphology, biological properties and physiochemical characteristics of their DNAs were compared. Electromicroscopic observation indicated that BS31 has a hexagonal head and contracted tail sheath, BS32 is a complex short-tailed phage and similar to phi 29 but differs from phi 29 in size and other properties. Two phages have a narrow spectrum of host range. The molecular weight of BS31 and BS32 DNAs are 62kb and 17kb respectively by EcoR1 endonuclease analysis. The G + C content of the DNAs are 45.7%(BS31) and 40.7%(BS32). Structural proteins of BS31 gave two major bands and at least ten minor ones; BS32 gave three major bands and six minor ones by SDS-polyacralamide gel electrophoresis.
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PMID:[Properties of two Bacillus subtilis bacteriophages]. 211 44

Comparison of catalytic properties of a Mn2(+)-dependent and a Ca2+, Mg2+ dependent endonucleases of rat liver cell nuclei was carried out. The Mn2(+)-dependent endonuclease has Mr 31 kDa by SDS-PAAG-electrophoresis; pH optimum 5.5; calcium-magnesium synergism less than 3 in rat liver DNA, RF M13 DNA and phage M13 DNA. The rate of hydrolysis of single strand and double strand circular DNA was the same. The Mn2(+)-dependent endonuclease split DNA by double hit manner, and didn't change the manner in the presence of different divalent cations. Ca2+, Mg2(+)-dependent endonuclease has pH optimum 6.5; calcium-magnesium synergism up to 40 in rat liver DNA and 175 in RF M13 DNA. The rate of hydrolysis of single strand DNA was higher than double-strand DNA.
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PMID:[DNAses of the cell nuclei: Mn2+-dependent endonuclease]. 217 66

Spectra of thymocyte nuclear DNAases of control and irradiated (4 Gy) rats have been investigated. Using the method of SDS-electrophoresis of nuclear proteins in DNA-polyacrylamide gel (PAAG) the authors managed to discover a number of polypeptides of 35, 32, 17.7, 17.2, and 16.4 kDA molecular mass possessing a DNAase activity. The enzyme of 35 kDA is only active in the presence of Ca2+ and Mg2+ ions. Nucleases of 32, 17.7, 17.2, and 16.4 kDA are active in the presence of Ca2+ ions and inactive in the presence of Mg2+ ions or in the absence of divalent cations. A simultaneous addition of Ca2+ and Mg2+ ions to the incubation medium causes a synergistic effect with respect to the manifestation of these DNAase activities. Nucleases of 32, 17.7, 17.2, and 16.4 kDa only emerge after the preliminary removal of histones by ion exchange chromatography on a column with CM-sephadex C-50. The enzymic activity of 32 kDA protein increases 60 min after irradiation and drops to the control value in 4 h. At the same time, the postirradiation increase in DNAase activity of a low-molecular weight enzyme group remains invariable throughout the entire period of observation (1-4 h). The preinjection of cycloheximide (CHI) prevents the postirradiation degradation of chromatin and, simultaneously, makes the enzymic activity, corresponding to 35 kDA protein, disappear at the electrophoregrams. The experiments with CHI permit to identify the given enzymic fraction as Ca/Mg-dependent endonuclease. This indicates the participation of normally pre-existing Ca/Mg-dependent endonuclease in implementing the process of chromatin enzymic degradation in the irradiated thymocytes.
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PMID:[The nuclear desoxyribonuclease (DNAse) spectrum of normal rat thymus cells and after whole-body x-ray irradiation]. 217 82

We previously reported a double-stranded endonuclease from HeLa cells, endonuclease R (endo R), which specifically cleaves duplex DNA at sites rich in G.C base pairs. In this report we describe the purification of endo R to near homogeneity by conventional and affinity chromatography. The molecular mass of the active form of endo R is approximately 115-125 kDa. SDS-gel electrophoresis reveals a major protein species of 100 kDa. The enzyme requires Mg2+ as a cofactor and is equally active on closed circular and linear duplex DNA substrates that contain G-rich sequences. A 50% reduction in cleavage activity is observed with Ca2+ ions and no double-stranded cleavage occurs with Zn2+. Use of Mn2+ causes an altered specificity at low concentrations of enzyme or divalent metal ion and nonspecific degradation of the substrate at higher concentrations. Endo R is strongly inhibited by sodium or potassium chloride and exhibits a wide pH optimum of 6.0-9.0. The pI of the enzyme is between 6.5 and 7.0. A 2-fold stimulation is observed with the addition of dGTP or dATP but specific cleavage is inhibited by ATP at an equivalent concentration. Cleavage activity is competitively inhibited 10-fold more efficiently by single-stranded poly(dG)12 than by other DNA competitors. The ends of endo R cleavage products contain 5'-phosphate and 3'-hydroxyl groups, and a significant portion of these products were substrates for T4 DNA ligase. Endo R appears to be a previously uncharacterized mammalian endonuclease.
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PMID:Purification and characterization of HeLa endonuclease R. A G-specific mammalian endonuclease. 235 41

An apurinic/apyrimidinic (AP) endonuclease (E.C.3.1.25.2) has been purified 1100 fold to apparent homogeneity from calf thymus by a series of ion exchange, gel filtration and hydrophobic interaction chromatographies. The purified AP endonuclease is a monomeric protein with an apparent molecular weight on SDS-PAGE of 37,000. On gel filtration the protein behaves as a protein of apparent molecular weight 40,000. DNA cleavage by this AP endonuclease is dependent on the presence of AP sites in the DNA. DNA cleavage requires the divalent cation Mg2+ and has a broad pH optimum of 7.5-9.0. Maximal rates of catalysis occur at NaCl or KCl concentrations of 25-50 mM. The amino acid composition and the amino-terminal amino acid sequence for this AP endonuclease are presented. Comparison of the properties of this AP endonuclease purified from calf thymus with the reported properties of the human AP endonuclease purified from HeLa cells or placenta indicate that the properties of such an AP endonuclease are highly conserved in these two mammalian species.
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PMID:Purification and amino-terminal amino acid sequence of an apurinic/apyrimidinic endonuclease from calf thymus. 244 59

The cytosolic untransformed molybdate-stabilized glucocorticoid-receptor complex from rat liver was eluted as a heterogenous peak containing two components with Stokes radii (Rs) of 8.3 nm and 7.1 nm when analyzed by size-exclusion HPLC even in the absence of molybdate. In contrast, the highly purified glucocorticoid receptor yielded a sharp symmetrical peak of Rs = 7.1 nm. We demonstrate that the 7.1-nm component could not result from a proteolytic degradation of the 8.3-nm receptor form. The same receptor heterogeneity was observed in thymus cytosol which contains less proteases than liver. After labeling with [3H]dexamethasone 21-mesylate and SDS/PAGE the same 94-kDa receptor band was revealed in both the 8.3-nm and 7.1-nm forms. Immunoblotting experiments showed that both the 94-kDa hormone-binding subunit and the 90-kDa heat-shock protein were present in the two different receptor forms. The 8.3-nm receptor form was converted to the 7.1-nm receptor form after treatment by ribonuclease A in the presence of molybdate and this effect was dose-dependent, being completely prevented by placental ribonuclease inhibitor (RNasin). In contrast, in the presence of molybdate, the 7.1-nm receptor form was ribonuclease-insensitive. Treatment of cytosol with RNase A in the absence of molybdate, partially shifted the untransformed receptor towards the 5.2-nm transformed receptor form. This effect was abolished by placental ribonuclease inhibitor. RNase S protein, an enzymatically inactive proteolytic fragment of RNase A, or S1 nuclease, which is specific for single-stranded nucleic acids, were ineffective when used instead of RNase A. In contrast, cobra venom endonuclease, which preferentially attacks double-stranded regions of small RNAs, caused a complete conversion of the 7-8-nm untransformed receptor to the 5.2-nm transformed receptor form. These results were not observed in the presence of molybdate. Addition of RNasin prior to heating cytosol in the absence of molybdate did not prevent the receptor from dissociating to the 5.2-nm form, suggesting that an endogenous RNase is not involved in the transformation process. The 7.1-nm receptor form was shifted to a 9.2-nm complex when incubated with an excess of GR 49 antireceptor antibody, whereas the 8.3-nm receptor form did not bind to the antibody.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:RNA binding to the untransformed glucocorticoid receptor. Sensitivity to substrate-specific ribonucleases and characterization of a ribonucleic acid associated with the purified receptor. 246 3


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