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)

Poly(ADP-ribose) polymerase activity was measured in a crude nuclear fraction isolated from HeLa cells. It was found that the addition of ammonium sulfate or other salts to the standard incubation medium inhibited the formation of poly(ADP-ribose). Through the use of alkaline sucrose density gradients it was also noted that this same increase in ionic strength inhibited the in vitro breakdown of the HeLa DNA. Additional experiments with alkaline sucrose density gradients and deoxyribonuclease I showed that the in vitro activity of poly(ADP-ribose) polymerase is largely dependent upon DNA fragmentation but that DNA fragmentation at least in vitro is not dependent upon the formation of poly(ADP-ribose). These observations imply that this nuclear enzyme is not extremely sensitive to changes in the ionic strength of the reaction media but is affected indirectly, supposedly through changes in the endonuclease activity of the HeLa nuclei. If this proves to be true, then the addition of salt to the incubation medium for poly(ADP-ribose) polymerase could prove to be a valuable tool for the study of ADP-ribosylation reactions.
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PMID:Increased ionic strength: effects on DNA fragmentation and poly(ADP-ribose) polymerase activity in HeLa nuclei. 309 21

A total of 517 strains of Staphylococcus aureus isolated at a hospital in Melbourne, Australia between 1946 and 1981 was examined for resistance to a range of antimicrobial agents and for the presence of plasmid DNA. The use of mixed-culture transfer and restriction endonuclease analysis showed that the determinants for resistance to penicillin and to the heavy metals were carried by several related plasmids of (15-23) X 10(6) mol. wt, and that tetracycline resistance was encoded on a plasmid of 2.8 X 10(6) mol. wt in strains isolated before 1970. These phenotypes were chromosomally encoded in the majority of strains isolated thereafter. Resistance to chloramphenicol throughout the study period was plasmid-mediated. Of five aminoglycoside-resistance phenotypes, one was plasmid-mediated and three were chromosomally encoded. The remaining phenotype, specifying low-level gentamicin resistance, was found to be located on the chromosome of early isolates, but in later strains was borne by an 18 X 10(6) mol. wt plasmid which also encoded resistance to quaternary ammonium compounds.
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PMID:Antibiotic resistance in Staphylococcus aureus isolated at an Australian hospital between 1946 and 1981. 384 19

The Staphylococcus aureus plasmid pSK1 carries Tn4001, a 4.7-kilobase (kb) transposon which specifies resistance to gentamicin, tobramycin, and kanamycin. In addition, pSK1 mediates resistance to trimethoprim and linked resistance to ethidium bromide (Ebr) and to quaternary ammonium compounds (Qar). Restriction endonuclease analysis of pSK1 and a deleted derivative of pSK1 revealed that the gene(s) responsible for Ebr Qar lies within a 5.2-kb HindIII fragment. This fragment has been cloned into the Escherichia coli plasmid vector pBR322, and transformants of an E. coli K-12 strain exhibited Ebr Qar. Subcloning of the 5.2-kb insert, combined with data from electron microscopic analysis of deleted derivatives of pSK1, located the Ebr Qar determinant(s) on a 2.3-kb segment of pSK1 DNA.
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PMID:Cloning and expression of Staphylococcus aureus plasmid-mediated quaternary ammonium resistance in Escherichia coli. 388 46

A new inactivation process for foot-and-mouth disease virus (FMDV) has been developed. This process is based on the activation of the FMDV endonuclease by incubation of unfractionated viral suspension or purified virions at 37 degrees C in the presence of high concentrations of monovalent cations such as K+, Cs+ or NH4+ at pH 8.5. This procedure completely inactivated several FMDV vaccine strains yielding preparations having similar amounts of 140S particles to untreated controls. The inactivation followed first-order kinetics and the rate of inactivation was faster than that achieved with other agents, e.g. binary ethyleneimine. Testing in suckling mice or tissue culture revealed no residual infectivity after inactivation. Virus particles purified from inactivated preparations showed (i) the same sedimentation coefficient as non-inactivated preparations, (ii) electrophoretic patterns of their viral capsid proteins identical to those derived from non-inactivated preparations, and (iii) extensive degradation of the 35S viral RNA. This method is safer than inactivation with aziridines because only innocuous chemicals are used in the process.
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PMID:Inactivation of foot-and-mouth disease virus vaccine strains by activation of virus-associated endonuclease. 608 82

A restriction endonuclease designated EcoVIII, an isoschizomer of HindIII, was isolated from Escherichia coli E1585-68 and purified by dextran-polyethylene glycol (DPG) phase partition, ammonium sulfate precipitation, phospho- and DEAE-cellulose chromatography, and hydroxylapatite chromatography. The purified EcoVIII was stable during the purification procedure and its high specific activity required 10 mM Mg2+. Unlike HindIII, EcoVIII exhibited a high specific activity even at low pH (pH 6.3) and showed the highest activity at 48 degrees C. Transformation of purified plasmid DNA from E. coli E1585-68 into K-12 indicated that the EcoVIII gene was carried on a multicopy 4.4-kb miniplasmid. EcoVIII seems to be preferable to HindIII for its production and use because of easier handling of producer cells and a wider range of activity.
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PMID:Isolation of restriction enzyme EcoVIII, an isoschizomer of HindIII, produced by Escherichia coli E1585-68. 609 26

DNA binding proteins present in the cytoplasm and nuclei of term placenta were isolated by DNA-cellulose chromatography and analysed by electrophoresis in high resolution polyacrylamide gradient gels. A denatured DNA specific protein of approximate molecular weight 34 000 daltons was the predominant DNA binding protein of the cytoplasm; this protein consisted of over 65% of the total DNA binding proteins of the 0.15 M NaCl eluate of the cytoplasm. The cytoplasmic extracts contained two additional DNA binding proteins of molecular weight 24 000 and 18 000 daltons and these proteins bound preferentially to ds DNA. All the three DNA binding proteins were also present in the nuclei and electrophoresis of histones in adjacent lanes indicated that they are not histones. The 34 000-dalton DNA binding protein has been purified by ammonium sulphate fractionation followed by phosphocellulose (PC) chromatography. The DBP eluted from the PC column between 0.125-0.15 M potassium phosphate. PC fractions containing electrophoretically pure 34 KD DBP showed an endonuclease activity capable of converting plasmid pBR 322 DNA to the linear form. Maximum endonucleolytic activity was observed in the presence of 3-5 mM Mg2+ and the enzyme activity was completely inhibited by 3 mM ethylenediamine tetraacetate.
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PMID:DNA-binding proteins of human placenta: purification and characterization of an endonuclease. 609 9

pppA(2'p5'A)n-1 ((2'-5')(A)n) synthetase is one of the mediators of interferon action. On activation by double-stranded RNA, it converts ATP into (2'-5')(A)n; in turn, (2'-5')(A)n activates an endonuclease (RNase L) which cleaves single-stranded RNA. We report a simple procedure for the isolation of pure (2'-5')(A)n synthetase from interferon-treated Ehrlich ascites tumor cells. The procedure involves differential precipitation of the ribosomal salt wash fraction with ammonium sulfate and chromatography on DEAE-cellulose and CM-cellulose. The apparent molecular weight of the enzyme is 105,000 as determined by gel electrophoresis in sodium dodecyl sulfate and about 85,000 when determined by centrifugation through a glycerol gradient. The size range of the (2'-5')(A)n produced by the enzyme extends from the dimer to at least the pentadecamer.
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PMID:Interferon, double-stranded RNA, and RNA degradation. Isolation of homogeneous pppA(2'p5'A)n-1 synthetase from Ehrlich ascites tumor cells. 615 3

Three enzymes possessing RNAase activity were isolated from barley seeds. These enzymes were further purified by ammonium sulphate precipitation DEAE-cellulose chromatography, gel filtration on Sephadex G-75 and DEAE-Sephadex A-50 chromatography. These enzymes have been characterized and classified as: 1. Plant RNAase I (EC 3.1.27.1). It has a pH optimum at 5.7 and molecular weight of 19 000. 2. Plant RNAase II (EC 3.1.27.1). It has a pH optimum at 6.35 and molecular weight of 19 000. 3. Plant nuclease I (EC 3.1.30.2). It has a pH optimum at 6.8 and molecular weight of 37 000. Two RNAases were purified to homogeneity by means of affinity chromatography on poly(G)-Sepharose 4B, as shown by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate.
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PMID:Purification and properties of two ribonucleases and a nuclease from barley seeds. 624 75

A procedure for simultaneous large-scale purification of the bacteriophage-T4-induced polynucleotide kinase, DNA ligase, RNA ligase and DNA polymerase has been developed. The method involves bacterial cell disruption by sonication, fractionation of cell extract with polymin P, salt elution from the polymin pellets, ammonium sulfate precipitation, and subsequent column chromatography purification of the enzymes. To enrich the enzyme content highly in the initial source non-permissive Escherichia coli B-23 cells infected with T4 amN82 phage were used. The procedure described is rapid, reproducible, high in yield, and able to handle preparations using from 1 g to 200 g cell paste. It can be easily scaled up. The method results in large amounts of the enzymes with very high specific activities, good stability essential lacking exonuclease and endonuclease contamination. The final enzyme preparations were efficiently used in DNA sequencing and in multiple experiments on construction of various recombinant DNAs for cloning and expression in vivo.
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PMID:A new procedure for the simultaneous large-scale purification of bacteriophage-T4-induced polynucleotide kinase, DNA ligase, RNA ligase and DNA polymerase. 626 Apr 93

The ATP-dependent deoxyribonuclease from Bacillus laterosporus has been purified to near homogeneity by a procedure involving ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephadex G-150 gel filtration, DEAE-Sephadex A-25 chromatography and DNA-cellulose affinity chromatography. The purified enzyme has a molecular weight of 210,000 +/- 8,000 as determined by sucrose gradient sedimentation. It is composed of two nonidentical polypeptide chains with close molecular weights of around 110,000. The substrate preference of the pure enzyme is essentially identical with the previous result obtained with the partially purified enzyme preparation (Anai, M., Mihara, T., Yamanaka, M., Shibata, T., & Takagi, Y. (1975) J. Biochem. 78, 105-114). Thus, the enzyme degrades double-stranded DNA about 100 times faster than heat-denatured DNA in the presence of ATP. Double-stranded DNA is not degraded to any measurable extent in the absence of ATP, but the enzyme exhibits activity toward denatured DNA in the absence of ATP. Furthermore, no endonuclease activity is observed on covalently closed circular duplex DNA and open circular duplex DNA.
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PMID:An adenosine triphosphate-dependent deoxyribonuclease from Bacillus laterosporus. Improved purification, subunit structure and substrate specificity. 626 32


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