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 specific endonuclease involved in the processing of tRNA precursors was isolated and partially purified from the posterior silk gland of Bombyx mori, and designated as RNase P.Bmo. This enzyme was shown to catalyze the conversion of 4.5 S precursor RNA to 4.1 S RNA by trimming the 5'-additional segment from the precursor RNA. RNase P.Bmo required divalent cations, Mg2+ or Mn2+. In the presence of these divalent cations, K+ or NH4+ activated the RNase P.Bmo reaction. Optimum pH was observed around 8.0. Ribosomal RNA's and mature tRNA from the silk gland were not cleaved by RNase P.Bmo. A 4.5 S precursor RNA fraction containing formycin, an adenosine analog, was less susceptible to RNase P.Bmo than the normal one. These results indicate that RNase P.Bmo has a high substrate specificity. An additional nuclease(s) was isolated. This activity was assumed to remove the extra 3'-segment of the 4.5 S precursor RNA.
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PMID:Purification and some properties of a specific nuclease which cleaves transfer RNA precursors from the posterior silk gland of Bombyx mori. 2 36

The major fraction of deoxyribonuclease activity from human urinary protein was purified 40-fold in about 14% yield. The enzyme shows an isoelectric point at pH 4.2 and has a molecular weight of 33,600+/-3,000. Optimum activity was shown at pH 6.8 in the presence of 12.5 mmol/l Mg2+ plus 1 mmol/l Ca2+. The enzymic reaction is inhibited by high ionic strength (greater than 300 mmol/l Na+). The purified enzyme readily hydrolyzes native DNA to oligodeoxyribonucleotides with an average chain length of 5.3+/-0.2 after exhaustive digestion. Therefore, this endonuclease may be designated as neutral deoxyribonuclease (deoxyribonucleate oligonucleotidohydrolase, EC 3.1.4.5).
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PMID:The major fraction of deoxyribonuclease activity from human urinary proteins. Purification and properties. 3 20

Alkaline ribonuclease (RNase) from polyribosomes derived from experimental granulation tissue has been purified 1900-fold through affinity chromatography. The preparation was homogeneous in sodium dodecyl sulfate (SDS) polyacrylamide-gel electrophoresis with an estimated molecular weight of 15 000. Purified RNase was completely inhibited in the presence of divalent ions Mg2+(100 mM) and Ca2+(100 mM) but activated slightly with Na+(50 mM). The enzyme is an endonuclease and the best substrates were poly(U), mixed RNA from yeast, rRNA from granulation tissue and poly(C). The estimated apparent Km-values were 0.037, 0.064, 0.13 and 0.27 g1-1, respectively. In polyribosomes RNase occurred in both free and p-chloromercuribenzoate (pCMB)-liberated forms. The total activity was at the highest but the proportion of the free activity minimal in the granulation tissue during the maximal synthesis of collagen.
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PMID:Alkaline ribonuclease associated with polyribosomes in fibroblasts of experimental granulation tissue. 3 15

Haemophilus influenzae Rf 232, showing the phenomena of restriction and modification, contains an endonuclease that inactivates in vitro the biological activity of DNAs lacking the strain-specific modification. This specific restriction endonuclease has been purified to near homogeneity by a procedure that includes DNA-agarose chromatography. This highly purified enzyme requires ATP and Mg2+ for activity and is stimulated by S-adenosylmethionine. The enzyme seems to cleave DNA at well-defined sites, since it produces a specific pattern of bands upon agarose gel electrophoresis. The enzyme has no ATPase activity. A methylase activity is observed in the course of the endonucleolytic reaction, which probably protects some of the DNA sites from cleavage.
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PMID:Purification and properties of a new restriction endonuclease from Haemophilus influenzae Rf. 3 45

A study has been made of the factors and mechanism leading to appearance of the so-called EcoRI activity described by Polisky et al. (1975) in the restrictase EcoRI preparations. The preparations of purified restrictase EcoRI, precipitated at 0.9 ammonium sulphate saturation, as well as that obtained using standard techniques have been found to contain an admixture of an endonuclease which at neutral pH and high ionic strength multiply cleaves those DNAs which normally have only one recognition site for EcoRI. Under the standard conditions for EcoRI digestion this activity is found only when large amounts of freshly isolated enzyme are added to the incubation mixture and it is sharply enhanced by replacement of Mg2+ with Mn2+. The number and size of DNA fragments produced under such conditions practically do not differ from those found under the so-called EcoRI conditions, that is for alkaline pH values and low ionic strength. The optimum incubation mixture for the EcoRI activity has been found to be 10 mM Tris . HCl buffer (pH 8.8) + 2 mM Mn2+. Similar activity is induced also by addition to EcoRI solution of 40--50% glycerol or a number of organic solvents (dimethylacetamide (DMA), dimethylformamide (DMF), dimethylsulphoxide (DMSO), sulphalane (SP) in concentrations from 1 to 6%. The EcoRI activity induced by 50% glycerol or at alkaline pH values and low ionic strength is suppressed or sharply inhibited by 2--3 mM parachloromercuribenzoate (PCMB), while EcoRI is not sensitive to this agent. The DNA fragments cleaved by EcoRI have cohesive termini and can be easily ligated. It is suggested that the EcoRI activity can be due not only (or largely not) to modification of the "recognizing capacity" of the EcoRI restrictase but not activation of a latent specific endonuclease which is present in the restrictase preparation as an impurity.
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PMID:EcoRI activity: enzyme modification or activation of accompanying endonuclease? 3 71

The presence of Ca2+, Mg2+-dependent endonuclease activity in isolated brain cell nuclei was demonstrated and a comparison of some peculiarities of chromatin autolysis in rat brain and liver cell nuclei was carried out. Endogenous brain nuclease hydrolyzes chromatin into its structural subunits; its specific activity is 10,5 times as low as compared to the endogenous nuclease activity in rat liver nuclei. The dependency of the chromatin autolysis rate on pH and ionic composition of the incubation medium in isolated rate brain and liver nuclei appeared to be the same. The presence of Mn2+ changed the autolysis nature both in brain and in liver cell nuclei, the relative (as compared to Mg2+-dependent) Mn2+-dependent activity being higher in the brain cell nuclei. Possible differences of brain and liver chromatin structure (e. g. the presence of regions free of nucleosomic organization in brain chromatin) are assumed.
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PMID:[Detection of endonuclease activity and several features of chromatin autolysis in brain cell nuclei]. 3 48

EndoR . NgoII, a class II restriction endonuclease isolated from Neisseria gonorrhoeae, was purified to electrophoretic homogeneity. We were able to separate it from another restriction endonuclease of N. gonorrhoeae, NgoI, by phosphocellulose chromatography. NgoII is an isoschizomer of HaeIII, a restriction endonuclease of Haemophilus aegyptius, and was found to recognize the deoxyribonucleic acid nucleotide base sequence GGCC. NgoII was able to digest phage lambda deoxyribonucleic acid over a wide pH range, with optimal activity at pH 8.5. The enzyme has an absolute requirement for Mg2+; maximal enzyme activity was observed at 1 mM Mg2+. The active enzyme has a molecular weight of 65,000 and appears to be composed of six subunits of identical molecular weight (11,000). No methylase activity could be detected in the purified enzyme preparation.
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PMID:NgoII, a restriction endonuclease from Neisseria gonorrhoeae. 3 16

We describe the partial purification of an endonuclease from calf thymus that nicks phage PM2 DNA irradiated with UV doses producing only a few pyrimidine dimers per molecule. It has much less activity on DNA that has been subjected to enzymatic photoreactivation after UV irradiation. The calf thymus endonuclease is different from other mammalian UV-endonucleases so far described in that it seems to be dimer specific. The enzyme is stimulated by Mg2+ and is inactive in the presence of EDTA. It binds to UV-irradiated DNA-Sepharose from which it is released by low concentrations of KCl. Gel filtration data indicate that the endonuclease may belong to a high molecular weight protein or protein complex. The enzyme is very labile and freezing increases its lability.
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PMID:UV-endonuclease from calf thymus with specificity toward pyrimidine dimers in DNA. 4 Feb 30

The specific restriction endonuclease of the Escherichia coli plasmid, P15, has been purified to apparent homogeneity by a procedure that includes DNA-cellulose chromatography as well as a new endonuclease assay. Sedimentation on glycerol gradients showed two peaks of activity with values of 11.3 S and 15.7 S. The highly purified enzyme requires ATP and Mg2+ for activity and is stimulated by S-adenosylmethionine. A methylase activity is observed in the course of the endonucleolytic reaction which protects some of the DNA sites from cleavage.
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PMID:Purification and properties of the P15 specific restriction endonuclease from Escherichia coli. 13

Over 95% of the deoxyribonuclease (DNase) activity of log-phase mycelia of Neurospora crassa is expressed as single-strand (ss) specific endonucleolytic activity. This activity is associated with three nucleases (D1, D2, and D3) which after partial purification from extracts, express activity with double-strand (ds) DNA as well. All three enzymes also degrade RNA at approximately the same rates that they degrade ss-DNA. D3 has been identified as endoexonuclease, an enzyme previously shown to have endonuclease activity with ss-DNA and RNA and exonuclease activity with ds-DNA, both of which are inhibited by ATP. D3 is inhibited by ATP, is relatively resistant to p-hydroxymercuribenzoate (PHMB), and sediments with an apparent molecular weight of 75 000. D2 has the properties of the previously described mitochondrial nuclease. It is a relatively unstable Mg2+-dependent endonuclease with no appreciable strand specificity for DNA. In addition, it is not inhibited by ATP and is strongly inhibited by PHMB and by the ethylenediamine tetraacetic acid (EDTA). It also sediments with an apparent molecular weight of 75,000. The properties of D1 are quite variable from one preparation to another. Freshly isolated D1 sediments with an apparent molecular weight of 180 000. It often shows some inhibition by ATP, but is relatively resistant to both PHMB and EDTA. However, on 'ageing,' the properties of D1 gradually convert to those of D2 with concomitant decrease in molecular weight, loss of inhibition by ATP, and increase in sensitivities to PHMB and EDTA. The results indicate that D1 is very likely a second form of the mitochondrial enzyme. Evidence was obtained for the presence of protein inhibitor(s) in crude extracts which may account for the masking of the ds-DNase activities of these enzymes in extracts. Two Rec-like mutants of Neurospora (uvs-3, and nuh-4) are deficient mainly inexpressed levels of D3, the endo-exonuclease. However, the levels of inactive endo-exonuclease precursor in these two mutants are higher than in the wild type. There may, therefore, be some defect in the conversion of precursor to active enzyme in these two mutants. Another mutant, which is not sensitive to mutagens relative to the wild (nuh-3), has depressed levels of both endo-exonuclease and the mitochondrial enzyme. Nuh-3 has some defect in the conversion of D1 to D2. Proteinases probably play some role in vivo in these enzyme conversions.
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PMID:The major intracellular alkaline deoxyribonuclease activities expressed in wild-type and Rec-like mutants of Neurospora crassa. 15 96


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