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)

Phosphodiesterase I from the venom of Bothrops atrox has been purified by successive chromatography on phosphocellulose P-11, hydroxyapatite, and DEAE-cellulose DE 52. The final product gave a single band on sodium dodecylsulfate-polyacrylamide gels and was free of endonuclease, 5' -nucleotidase, and unspecific alkaline phosphatase activity. It was concentrated in an Amicon ultrafiltrator without loss of activity and could be stored in 10 mM magnesium acetate and 10% glycerol at 4 degrees C for at least a year. Under optimal conditions, the enzyme reaction required 15 mM Mg2+ and a pH of 9.2. Phosphodiesterase I is relatively thermostable and, in the presence of a macromolecular substrate, was not denatured after 4 h at 55 degrees C. The pure enzyme offers new possibilities for sequence studies on highly structured nucleic acids at elevated temperatures.
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PMID:Purification and characterization of phosphodiesterase I from Bothrops atrox. 17 76

Two species of restriction endonuclease were isolated by gel filtration and DEAE-cellulose chromatography from a cell-free extract of Bacillus amyloliquefaciens (B. subtilits) N strain; a lower molecular weight endonuclease (endonuclease R.BamNI) and a higher molecular-weight one (endonuclease R.BamNx). Both of them required only Mg2+ for their activities. Endonuclease R.BamNx introduced a larger number of site-specific scissions in Excherchia coli phage lambda DNA that endonuclease R.BamNI did. Endonuclease R.BamNx cleaved Bacillus phage phi 105C DNA at the specific sites which are classified into two groups: one type of sites is modified by B. amyloliquefaciens H strain in vivo while the other is not affected. It was also active on DNA'S OF E. coli phage T7, lambdadvl, Simian virus 40 (SV40) and colicinogenic factor ColEI and was inactive on DNAs of Bacillus phages phi 29 and M2. Endonuclease R.BamHI isolated from H strain by Wilson and Young. This endonuclease was active on DNAs of phage lambda, lambdadvl and SV40, adn was inactive on DNAs of phages phi 105C, phi 29, M2 and T7, and ColEI DNA.
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PMID:The restriction endonucleases in Bacillus amyloliquefaciens N strain. Substrate specificities. 18 57

An endoribonuclease has been isolated from HeLa cell nuclei. Approximately 70% of the enzyme appears to be nucleolar bound; 30% is in the nucleoplasm. Studies of the purified enzyme reveal that the enzyme is an endonuclease of estimated molecular weight 16,000. It produces oligonucleotides bearing 5'-phosphate end groups. The enzyme degrades poly(C) and poly(U), as well as rRNA and heterogeneous nuclear RNA, Poly(A), double-stranded RNA, and DNA are not cleaved. The enzyme is heat-labile and is inhibited by 10mM Mg2+ and 50 mM NaCl. The enzyme is probably distinct from previously described nuclear endonucleases.
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PMID:Purification and characterization of an endoribonuclease from nucleoplasm and nucleoli of HeLa cells. 18 53

Endonuclease activities of cytoplasmic extracts of BSC-1 (E1) and BHK-21-cl 13 (E2) cells were assayed with SV-40 as a substrate and analysed by velocity sedimentation in alkaline and neutral sucrose gradients. Endonucleases were found to require Mg2+ ions for their activity. E1 endonuclease generated linear 6 S DNA fragments, pointing to non-random double-strand cleavage of DNA ; the action of E2 endonuclease resulted in double-strand DNA cleavage to fragments heterogeneous in size. Both endonucleases were inhibited by ATP. The inhibitory effect of actinomycin D (AD) was proportional to the AD/DNA molar ratio. AD+ATP association as well as the presence of ethidium bromide altered the cleavage pattern of E1 towards the predominance of single-strand breaks.
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PMID:Alteration of the cytoplasmic endonuclease cleavage pattern of SV-40 deoxyribonucleic acid in the presence of ATP, actinomycin D and ethidium bromide. 19 89

A homogeneous preparation of venom phosphodiesterase from Crotalus adamanteus possesses an intrinsic endonuclease activity, specific for superhelical (form I) and single-stranded DNA. The phosphodiesterase degrades single-stranded T7 DNA by endonucleolytic cleavages. Duplex T7 DNA is hydrolyzed by the liberation of acid-soluble products simultaneously from the 3' and 5' termini but without demonstrable internal scissions in duplex regions. Since venom phosphodiesterase is known to hydrolyze oligonucleotides stepwise from the 3' termini, the cleavage at the 5' end of duplex T7 DNA is ascribed to an endonuclease activity. Form I PM2 DNA is nicked to yield first relaxed circles and then linear DNA which is subsequently hydrolyzed only from the chain termini. The linear duplex DNA intermediates consist of a discrete series of fragments (11 are usually resolved on agarose gels) with initial molecular weights ranging from 6.3 x 10(6) (the intact PM2 DNA size) to approximately 1 x 10(6). The cleavage of the form I molecule must, therefore, occur at a limited number of unique sites. The enzyme also cleaves nonsuperhelical, covalently closed circular PM2 DNA but at a 10(4) times slower rate. Both the endonuclease activity on form I DNA and the known exonuclease activity co-migrate on polyacrtkanude gels, are optimally active at pH 9, are stimulated by small concentrations of Mg2+, and are similarly inactivated by heat, reducing agents, and EDTA.
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PMID:An endonuclease activity of venom phosphodiesterase specific for single-stranded and superhelical DNA. 20 Jun 16

In the presence of 100 mM Tris buffer (pH 7.5) and 1-10 mM Mg2+ EcoRI endonuclease cleaves DNA at a specific nucleotide sequence and in a characteristic way: -GAATTC-. But if Mg2+ is replaced by Mn2+, the specificity of the cleavage is relaxed and cleavages occur at many other sites; moreover, there appears to be a hierarchy of cleavage rates at the pseudo-EcoRI restriction sites. For example, SV40 DNA is cleaved only once in the usual digestion conditions, but with Mn2+ more than ten cleavages are made; the five most rapidly cleaved SV40 DNA map locations are 0/1.0 larger than 0.93 larger than 0.33 approximately equal to 0.42 larger than 0.29 approximately equal to 0.40 larger than 0.25. Mn2+ also alters the restriction specificity of HindIII but not HpaII endonuclease.
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PMID:Altering the specificity of restriction endonuclease: effect of replacing Mg2+ with Mn2+. 20 Dec 81

A DNA endonuclease, Endo-I, which cleaves superhelical DNAs, has been isolated from avian myeloblastosis virions stripped of their coats by mild detergent treatment. The enzyme has a broad pH optimum around 7.5-8.0 and requires Mg2+ for activity. A second endonuclease, Endo-II, with a requirement for Mn2+, also present in viral cores, copurified with avian myeloblastosis virus alpha beta DNA polymerase (reverse transcriptase, RNA-dependent DNA nucleotidyltransferase) and similarly cleaved superhelical DNAs. Heat denaturation and sodium fluoride and N-ethylmaleimide inhibition studies were carried out to demonstrate a possible relationship between the two endonucleases and the viral DNA polymerase and RNase H activities. It appears that Endo-II may be an intrinsic activity of the polymerase.
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PMID:DNA endonucleases associated with the avian myeloblastosis virus DNA polymerase. 22 53

Highly purified nuclease TT1 from T. thermophilus HB8 acts on a linear single- and double-stranded DNA as an exonuclease and produces 5'-mononucleotides either from the 5'- or 3'-terminus. It was found that the enzyme also possesses an endonuclease activity specific for superhelical (form I) and single-stranded circular DNA. Form I of various kinds of DNA (phi X174, PM2, Co1E1 and RF 1010 etc.) is nicked to yield first relaxed circles (form II) and then nicked at the opposite site to yield unit length linear DNA (form III), which is subsequently hydrolyzed from the 5'- or 3'-terminus. A single cleavage of the form I of phi X174 DNA seemed to occur at a limited number of unique sites. Both endonuclease and the known exonuclease activities co-migrate on polyacrylmide gels, show the same pH and temperature optima, are stimulated by Mg2+ and are inactivated by EDTA similarly.
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PMID:An endonucleolytic activity of nuclease TT1 specific for superhelical DNA. 23 56

The molecular basis for the inhibition of the Ca2+,Mg2+-dependent endonuclease resulting from the formation of poly(adenosine diphosphate ribose) (ADP-Rib) was studies in a simplified system containing purified rat liver or bull semen endonuclease, purified rat liver poly(ADP-Rib) synthetase, [3H]NAD+, and DNA. Poly-(adp-rib) synthetase activity was stimulated when Ca2+, Mg2+-dependent endonuclease was added to the reaction mixture in place of histones, suggesting that the endonuclease can act as an acceptor for ADP-Rib. Evidence was presented to show that the ADP-Rib moiety of [3H]NAD+ was incorporated in the endonuclease fraction. The [3H]ADP-Rib bound to the endonuclease was in the form of monomers and oligomers and not long chain polymers. The present results suggest that the Ca2+,Mg2+-dependent endonuclease was ADP-ribosylated when the endonuclease was incubated with poly(ADP-Rib) synthetase and NAD+.
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PMID:Evidence for adenosine diphosphate ribosylation of Ca2+, Mg2+-dependent endonuclease. 23 25

Two new endonuclease activities, endonuclease B and endonuclease C, obtained from yeast nuclear preparations have been separated and partially characterized. Endonuclease B has a primary requirement for Mn2+ which cannot be replaced by Mg2+ or Ca2+, and makes single-strand scissions in double-stranded DNA. Endonculease C is activated by either Mn2+ or Mg2+, and makes single-strand scissions with Mg2+, while with Mn2+, scissions are made which result in double-strand breaks. Neither enzyme is active on denatured DNA, and both are inhibited by yeast RNA. Both enzymes exhibit pH optima at pH 5.0 and PH 7.2, and leave 5'-phosphoryl termini.
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PMID:Studies on deoxyribonucleases from Saccharomyces cerevisiae. Characterization of two endonuclease activities with a preference for double-stranded DNA. 23 90


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