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)

Activation of Ag-specific T cell hybridomas with a high density of immobilized anti-CD3 antibody resulted in not only secretion of IL-2 but also cell death of up to 60 to 80% in selected hybridomas after 14 h. Similar results were obtained with V beta 8+ T cell hybridomas stimulated with cross-linked F23.1 antibody. In these activated hybridomas, we found that DNA was fragmented into 180- to 200-bp multiples. DNA fragmentation was not observed when T cells were maintained after killing with anti-Thy-1 plus C or with heat treatment at 45 degrees C, nor when T cells were incubated with fixed anti-CD4 antibody. Furthermore, fragmentation was detectable at 6 h after incubation when almost all of the cells were still viable as evaluated by trypan blue dye exclusion test. Cell death was prevented by addition of EGTA, cycloheximide, actinomycin D, and zinc, suggesting that the induction of cell death requires Ca2+ influx, newly synthesized protein(s), and involvement of endonuclease.
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PMID:T cell receptor-mediated DNA fragmentation and cell death in T cell hybridomas. 213 93

P1 nuclease, a zinc-dependent single-strand specific endonuclease from Penicillium citrinum, has been crystallized in three different space groups using either ammonium sulphate or polyethylene glycol 4000 as the precipitating agent. The crystals diffract to between 3 A and 2.2 A. A 4.5 A electron density map has been calculated for a tetragonal crystal form, based on a platinum derivative, and was improved by solvent flattening. The boundaries of the two molecules in the asymmetric unit are clearly visible in most regions and the presence of rod-like density features are indicative of a rather high alpha-helix content. The highest density peaks in the map were identified as a trinuclear zinc cluster present in each monomer by a difference Fourier of an EDTA-soaked crystal.
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PMID:Crystallisation and preliminary crystallographic analysis of P1 nuclease from Penicillium citrinum. 217 Jun 61

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

A computer analysis of the amino acid sequences from the putative gene products of retroviral pol genes has revealed a 150-residue segment that is homologous with the ribonuclease H of Escherichia coli. The segment occurs at the carboxyl terminus of the region assigned to the 90-kDa reverse transcriptase polypeptide. In contrast, a section nearer the amino terminus of this sequence can be aligned with nonretroviral polymerases. The order of activities in the pol gene is thus: polymerase-ribonuclease-endonuclease. On another note, all retroviral endonuclease sequences contain a consensus zinc-binding "finger." This should not be confused with the well-known zinc requirement of reverse transcriptases.
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PMID:Computer analysis of retroviral pol genes: assignment of enzymatic functions to specific sequences and homologies with nonviral enzymes. 242 13

An endonuclease that cleaves ultraviolet light (UV)-damaged, supercoiled plasmid DNA was partially purified from spinach leaves (Spinacia oleracea) by a series of column chromatography steps. Dialysis of the enzyme against EDTA resulted in a greater than 90% loss of activity which could be fully restored following the addition of Zn2+, suggesting that divalent cations are associated with the active enzyme. The spinach endonuclease cleaved duplex, UV-damaged, end-labelled DNA of defined sequence at positions of adenine in the presence of salt (KH2PO4 or NaCl) concentrations of 50 mM or higher. Cleavage of UV-irradiated DNA was dose-dependent and increased steadily within a fluence range of 50-10,000 J/m2. The UV damage requirement and adenine cleavage specificity could be eliminated with lower salt concentrations (0-25 mM), suggesting that the endonuclease recognizes and incises single-stranded DNA. The properties of this enzyme, which we have termed nuclease SP, suggest that it may mediate a role in DNA repair and/or recombination processes in spinach.
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PMID:Partial purification and characterization of an endonuclease from spinach that cleaves ultraviolet light-damaged duplex DNA. 249 26

The restriction endonuclease FokI from Flavobacterium okeanokoites was purified to homogeneity. Based on gel filtration, sedimentation and sodium dodecyl sulfate-polyacrylamide-gel electrophoresis, the following properties of the enzyme were determined: FokI exists in one active monomeric form, and has an Mr of 64-65.4 x 10(3).FokI is a strongly basic protein with an isoelectric point of 9.4. The enzyme exhibits restriction activity in the pH range 5.0 to 10.5 (maximum level at pH 7.0-8.5) and its divalent cation requirement is satisfied not only by Mg2+, but also by Co2+, Mn2+, Ni2+, Cd2+, Zn2+ and Fe2+.
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PMID:Purification and characterization of the FokI restriction endonuclease. 258 11

The amino acid composition and NH2-terminal amino acid sequence of barley nuclease (EC 3.1.30.2) were determined. The amino acid composition is similar to that of mung bean nuclease, and therefore the biochemical properties of barley nuclease were characterized and compared with those of mung bean and other plant nucleases. The 3'-nucleotidase activity of barley nuclease is greater for purine than for pyrimidine ribonucleotides. The enzyme has little activity towards ribonucleoside 2' and 5'-monophosphates, and deoxyribonucleoside 3' and 5'-monophosphates, and is also inactive towards the 3'-phosphoester linkage of nucleoside cyclic 2',3' and 3',5'-monophosphates. The enzyme hydrolyzes dinucleoside monophosphates, showing strong preference for purine nucleosides as the 5' residues. Barley nuclease shows significant base preference for homoribonucleic acids, catalyzing the hydrolysis of polycytidylic acid greater than polyuridylic acid greater than polyadenylic acid much greater than polyguanylic acid. The enzyme also has preference for single-stranded nucleic acids. Hydrolysis of nucleic acids is primarily endonucleolytic, whereas the products of digestion possess 5'-phosphomonoester groups. Nuclease activity is inhibited by ethylenediaminetetraacetic acid and zinc is required for reactivation. Secretion of nuclease from barley aleurone layers is dependent on the hormone gibberellic acid [Brown, P.H. and Ho, T.-h. D. (1986) Plant Physiol. 82, 801-806]. Consistent with these results, gibberellic acid induces up to an eight-fold increase in the de novo synthesis of nuclease in aleurone layers. The secreted enzyme is a glycoprotein having an apparent molecular mass of 35 kDa. It consists of a single polypeptide having an asparagine-linked, high-mannose oligosaccharide. The protein portion of the molecule has a molecular mass of 33 kDa.
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PMID:Biochemical properties and hormonal regulation of barley nuclease. 282 11

Gel shift assays have been employed to examine the association of the thyroid hormone receptor with specific DNA sequences in the 5'-flanking DNA of the rat growth hormone (rGH) gene. This DNA is known to have structure(s) that mediate thyroid hormone effects on the rGH promoter. The receptors used were obtained from preparations purified 300-500-fold from rat liver nuclear extracts and contained about 1% pure receptors. Thyroid hormone receptor binding to DNA was assessed by monitoring protein-bound 32P-labeled restriction endonuclease fragments in parallel with L-tri[125I]iodothyronine-labeled protein-DNA complexes. The receptors were found to bind specifically to four different regions of the rGH 5'-flanking DNA (nucleotides -1730 to -1230, -530 to -230, -181 to -149, and -149 to +12) numbered with respect to the transcriptional start site. The specificity of the binding was documented by the finding that the receptor did not bind to other rGH 5'-flanking DNA sequences or to several other DNAs and by the fact that only the DNAs exhibiting specific binding could block the binding of radiolabeled DNA. The binding was also detected in NaCl concentrations up to 140 mM, reduced by Mg2+ concentrations up to 5 mM, and inhibited by 1 mM zinc. The DNA sequence-specific binding of the receptor was found to require occupancy of the receptor by the hormone (L-triiodothyronine) and could also be observed when the receptor was occupied by the thyroid hormone antagonist amiodarone. These results indicate that thyroid hormone receptors interact specifically with several sites on the 5'-flanking DNA of the rGH gene and that hormone occupancy is not required for the binding. Thus, thyroid hormone may act by stimulating a transcriptional activation function of the receptor rather than by stimulating DNA binding per se.
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PMID:The thyroid hormone receptor binds to multiple domains of the rat growth hormone 5'-flanking sequence. 283 88

We have characterized a 3'-nucleotidase activity of T. brucei. The enzyme has a pH optimum of 8.7, is inactivated by chelating agents and stimulated by divalent cations. It is inhibited by Zn2+, Mn2+, pyrophosphate and the trypanocidal drug suramin for which it has a Ki of 3 microM. From cell fractionation experiments it is concluded that the enzyme is located in the plasma membrane. Alkaline 3'-endoribonuclease is also located in the plasma membrane of T. brucei and this activity shares a great number of properties with the 3'-nucleotidase activity, including its sensitivity to suramin. The possibility that both 3'-nucleotidase and endonuclease activities are catalyzed by the same enzyme cannot be excluded.
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PMID:Localization of 3'-nucleotidase and calcium-dependent endoribonuclease in the plasma-membrane of Trypanosoma brucei. 288 57

An RNase activity was found to be present in rat brain and liver and was strongly bound to the nucleoprotein fractions of these tissues. It could not be solubilized by treatment with acid or by lipid solvents. The pattern of oligonucleotides produced during hydrolysis by this enzyme indicated that it was probably an endonuclease with restricted specificity. It was inhibited by zinc ions and by low pH.
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PMID:Occurrence of a nucleoprotein bound RNase in rat brain and liver. 308 63


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