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)

A new restriction endonuclease, designated as ApaLI, was purified from cell-free extracts of Acetobacter pasteurianus IFO 13753 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and Fast Protein Liquid Chromatography on Mono Q HR 5/5. The purified enzyme was homogeneous on polyacrylamide gel disc electrophoresis. The molecular weight of the purified enzyme was calculated as 26,000 daltons by gel filtration using Sephadex G-200, and the isoelectric point of the purified enzyme was 4.8 by ampholine sucrose-density gradient isoelectric focusing. The purified enzyme cleaved lambda, Ad2, SV40, M13mp18 RF 1, psi X174 RF I and pBR322 DNAs at 4, 7, 0, 0, 1 and 3 sites, respectively. The purified enzyme worked best at 37 degrees C and pH 8.0 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 25mM NaCl. However, the purified enzyme did not require NaCl necessarily for the enzyme reaction. The purified enzyme recognized the palindromic hexanucleotide DNA sequence, 5'-GTGCAC-3' and cut between G and T, producing a 5'-cohesive tetranucleotide extension.
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PMID:Purification, properties and recognition sequence and cleavage site determinations of restriction endonuclease from Acetobacter pasteurianus IFO 13753 (ApaLI). 136 91

A new restriction endonuclease, designated as AgeI, was purified from cell-free extracts of a marine bacterium, "Agrobacterium gelatinovorum" IAM 12617 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and FPLC on Mono Q (HR 5/5) and Superose 12 (HR 10/30). The purified enzyme was homogeneous on SDS-polyacrylamide gel disc electrophoresis and free from other phosphatase and exonuclease activities on ligation-recutting test. The relative molecular mass of the enzyme was 24,000 daltons by SDS-polyacrylamide gel disc electrophoresis. The gel filtration using Superose 12 (HR 10/30) gave the same calculation (23,000 daltons). These data indicated that the enzyme is a monomer. The isoelectric point of the enzyme was 6.5. The purified enzyme cleaved lambda and Ad2 DNAs at 10 or more and 5 sites, respectively. However, the purified enzyme did not cleave SV40, phi X174 RF I, M13mp 18 RF I or pBR322 DNAs. pBR328 DNA was cleaved at 1 site by the purified enzyme. The purified enzyme worked best at 37 degrees C and pH 7.5 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 50 mM NaCl. The purified enzyme did not require monovalent cations necessarily for the enzyme reaction. The enzyme recognized the palindromic hexanucleotide DNA sequence 5'-ACCGGT-3' and cut between A and C, producing a 5'-cohesive tetranucleotide extension.
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PMID:Purification, properties and determinations of recognition sequence and cleavage site of restriction endonuclease from "Agrobacterium gelatinovorum" IAM 12617, a marine bacterium (AgeI). 136 92

The restriction endonuclease AatII was purified from cell-free extracts of Acetobacter aceti IFO 3281 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on DEAE-Toyopearl 650S, heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and FPLC on Mono Q and on Superose 12 (gel filtration). The purified enzyme was homogeneous on SDS-polyacrylamide gel disk electrophoresis. The relative molecular mass of the purified enzyme was 190,000 daltons by gel filtration. The SDS-polyacrylamide gel disk electrophoresis gave the relative molecular mass of 47,500 daltons. These data indicated that the purified, native enzyme is a tetramer (190,000 daltons) composed of four 47,500-dalton subunits. The isoelectric point of the enzyme was 6.0. The purified enzyme was intensely activated by manganese ion (50-fold increase or more when compared with magnesium ion). The enzyme worked best at 37 degrees C and pH 8.5 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MnCl2 and 50 mM NaCl. The enzyme recognizes the same palindromic hexanucleotide sequence 5'-GACGTC-3', cuts between T and C and produces a 3'-tetranucleotide extension in the presence of MnCl2, as it does in the presence of MgCl2.
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PMID:Purification of restriction endonuclease from Acetobacter aceti IFO 3281 (AatII) and its properties. 136 9

A restriction endonuclease, designated as DmaI, was purified from cell-free extracts of Deleya marina IAM 14114 by streptomycin treatment, ammonium sulfate fractionation and two steps of chromatographies on heparin-Sepharose CL-6B and Mono Q (HR 5/5, FPLC). The purified enzyme was homogeneous on SDS-polyacrylamide gel disk electrophoresis and a ligation-recutting test. The relative molecular mass measurements of the purified enzyme gave 28,000 daltons by SDS-polyacrylamide gel disk electrophoresis and 56,000 daltons by gel filtration. These data indicated that the purified enzyme (56,000 daltons) has a dimeric structure composed of two 28,000-dalton subunits. The isoelectric point was 5.5. The purified enzyme worked best at 37 degrees C in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 100 mM NaCl (pH 7.5). The enzyme was stable up to 55 degrees C and between pH 7.0 and 9.0. The purified enzyme recognizes the palindromic hexanucleotide DNA sequence 5'-CAGCTG-3', cuts between G and C and produces a flush end (isoschizomer of PvuII).
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PMID:Purification and properties of restriction endonuclease from Deleya marina IAM 14114, a marine bacterium (DmaI). 136 11

Bacteriophage-T4 UV endonuclease nicks the C(3')-O-P bond 3' to AP (apurinic or apyrimidinic) sites by a beta-elimination reaction. The breakage of this bond is sometimes followed by the nicking of the C(5')-O-P bond 5' to the AP site, leaving a 3'-phosphate end; delta-elimination is proposed as a mechanism to explain this second reaction. The AP site formed when this enzyme acts on a pyrimidine dimer in a polynucleotide chain undergoes the same nicking reactions. Micrococcus luteus UV endonuclease also nicks the C(3')-O-P bond 3' to AP sites by a beta-elimination reaction. No subsequent delta-elimination was observed, but this might be due to the presence of 2-mercaptoethanol in the enzyme preparation.
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PMID:Bacteriophage-T4 and Micrococcus luteus UV endonucleases are not endonucleases but beta-elimination and sometimes beta delta-elimination catalysts. 247 12

The catalytic properties of the HhaII restriction endonuclease were studied using plasmid pSK11 DNA containing a single 5'-G-A-N-T-C HhaII cleavage site as substrate. Reactions were followed by two methods: 1) gel electrophoretic analysis of nicked circular and linear DNA products, or 2) release of 32P-labeled inorganic phosphate from specifically labeled HhaII sites in a reaction coupled with bacterial alkaline phosphatase. The enzyme is optimally active at 37 degrees C in 10 mM Tris-HCl (pH 9.1) and 4-10 mM MgCl2 without added NaCl. Activity is stabilized by the presence of 2-mercaptoethanol and 0.2% Triton X-100 or 50 microgram/ml bovine serum albumin. At enzyme concentrations below 10 nM and using pSK11 as substrate, initial kinetic rates were dependent on the order of mixing of reactants. A lag of 3-4 min was observed if enzyme or substrate was added last. Preincubation of substrate and enzyme followed by initiation of the reaction with MgCl2 or preincubation of the enzyme with nonspecific DNA followed by initiation with substrate eliminated or reduced the lag, respectively, and speeded up the reactions. Under a wide range of reaction conditions, nicked pSK11 DNA accumulated early, while linear molecules appeared later, suggesting that HhaII cleaves one strand at a time in separate binding events. The apparent Km for covalently closed pSK11 DNA molecules was approximately 17 nM, and the turnover number for the conversion of covalent to nicked sites was 1.1 single strand scissions/min. Pre-steady state kinetic analysis indicated that cleavage of the first phosphodiester bond in a site is first order with a rate constant of about 0.8 min-1, while cleavage of the second phosphodiester bond is first order with a rate constant of about 0.2 min-1.
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PMID:Catalytic properties of the HhaII restriction endonuclease. 299 12

A new sequence specific endonuclease, Mra I has been purified from Micrococcus radiodurans. This enzyme cleaves bacteriophage lambda DNA at three sites, adenovirus type 2 DNA at more than 12 sites and has a unique site on phi X174 DNA. It has no sites on SV40, PM2 and pBR322 DNA. The three sites on phage lambda DNA are different from those cleaved by Sma I, Xma I and Xor II. The sites of cleavage are located at 0.424, 0.447 and 0.834 fractional lengths on the physical map of lambda DNA. Mra I is shown to be an isoschizomer of Sac II and Sst II recognizing the palindromic nucleotide sequence '5-CCGC reduced GG-3'. The enzyme shows an absolute requirement of Mg2+, but is active in the absence of added 2-mercaptoethanol. The enzyme shows activity at a broad range of temperature and pH with an optimum at 45 degrees C and pH 7.0. Mra I represents the first restriction enzyme from a bacterium whose DNA lacks modified methylated bases.
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PMID:A sequence specific endonuclease from Micrococcus radiodurans. 628 77

An endonuclease active upon single-stranded DNA has been extensively purified from Ustilago maydis. The native form of the enzyme appears to be a single polypeptide chain of 55,000 daltons. The enzyme does not require addition of divalent cations for activity, but is stimulated severalfold by the transition metals Co2+, Mn2+, and Zn2+. It is strongly inhibited by ethylenediaminetetraacetic acid and 2-mercaptoethanol. The products of reaction are mononucleotides and small oligonucleotides bearing a 5'-phosphomonoester group. Superhelical DNA is cleaved by the enzyme to an open circular form, then cut to form a linear molecule. Relaxed closed circular duplex DNA is resistant to cleavage. Heteroduplex relaxed circular DNA molecules containing nonhomology or damage in only one strand were constructed and tested as substrates for the enzyme. The rate of enzymatic cleavage was found to be high relative to a control when molecules containing depurinated, deaminated, or radiation damaged sites were tested. Molecules containing a single mismatched base pair were not cleaved any faster than a completely base-paired control, unless reactions were carried out under conditions likely to introduce additional structural distortions in the DNA. Linear duplex DNA exposed to the enzyme is progressively shortened by digestion from both 5' and 3' termini.
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PMID:Studies on nuclease alpha from Ustilago maydis. 722 71

The major nuclease from Mycoplasma penetrans has been purified to homogeneity. The enzyme seems to be present as a membrane-associated precursor of 50 kDa and as a peripheral membrane monomeric polypeptide of 40 kDa that is easily removed by washing of cells with isotonic buffers and in the aqueous phase upon Triton partitioning of Triton X-114-solubilized protein. The 40-kDa nuclease was extracted from M. penetrans cells by Triton X-114 and phase fractionation and was further purified by chromatography on Superdex 75 and chelating Sepharose (Zn2+ form) columns. By gel filtration, the apparent molecular mass was 40 kDa. The purified enzyme exhibits both a nicking activity on superhelical and linear double-stranded DNA and a nuclease activity on RNA and single-stranded DNA. No exonuclease activity was found for this enzyme. This nuclease required both Mg2+ (optimum, 5 mM) and Ca2+ (optimum, 2 mM) for activity and exhibited a pH optimum between pH 7 and 8 for DNase activity. It was inhibited by Zn2+, Mn2+, heparin, sodium dodecyl sulfate, and chelator agents such EDTA and EGTA, but no effect was observed with ATP, 2-mercaptoethanol, N-ethylmaleimide, dithiothreitol, nonionic detergents, phenylmethylsulfonyl fluoride, and iodoacetamide. Nuclease activity was inhibited by diethylpyrocarbonate at both pH 6 and 8 and by pepstatin, suggesting the involvement of a histidine and an aspartate in the active site. When added to human lymphoblast nuclei, the purified M. penetrans endonuclease induced internucleosomal fragmentation of the chomatin into oligonucleosomal fragments. On the basis of this result, and taking into account the fact that M. penetrans has the capacity to invade eucaryotic cells, one can suggest, but not assert, that produced Ca2+/Mg2+-dependent endonuclease may alter the nucleic acid metabolism of host cells by DNA and/or RNA degradation and may act as a potential pathogenic determinant.
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PMID:Purification and characterization of Mycoplasma penetrans Ca2+/Mg2+-dependent endonuclease. 907 6

CpG endonuclease activity was identified in nuclear extracts obtained from mouse lung tumors. Enzyme activity was determined using a 333 bp polymerase chain reaction product of the estrogen receptor-alpha gene that contained either radiolabeled cytosine or tritium-labeled methyl groups at CpG sites. Activity was measured as the release of radioactivity from the substrate. The product of the nuclease activity was identified by high pressure liquid chromatography (HPLC) as either 5-methyl-2'-deoxycytidine when the CpG sites in the substrate were methylated or 2'-deoxycytidine when the CpG sites were not methylated. The CpG endonuclease activity was dependent on nuclear protein and temperature, had a proclivity for double-stranded over single-stranded DNA and was inhibited by ethylenediaminetetraacetic acid or 2-mercaptoethanol. Strain A/J mouse lung tumors induced by vinyl carbamate had a greater level of CpG endonuclease activity than non-involved lung tissue. Budesonide, a potent chemopreventive agent in mouse lung, not only prevented an increase in CpG endonuclease activity in lung tumors but, when administered to mice with established tumors, also decreased the level of endonuclease activity in the tumors. The effect of budesonide on CpG endonuclease activity in lung tumors was inversely related to its published effect on DNA methylation in mouse lung tumors, i.e. the drug decreased CpG endonuclease activity and increased the methylation of DNA. The increased CpG endonuclease activity in mouse lung tumors and its inhibition by budesonide would suggest this endonuclease as a potential molecular target for chemoprevention.
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PMID:Modulation by budesonide of a CpG endonuclease in mouse lung tumors. 1736 Oct 11


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