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)

The nuclei from the control and irradiated (3 h after irradiation at a dose of 10 Gy) thymocytes were preincubated with NAD in conditions optimal for poly (ADP) ribosylation. This was shown to decrease by 6-7- and 2-3 times, respectively, the rate of autolytic cleavage of DNA by Ca/Mg-dependent endonuclease. The inhibitors of poly (ADP-riboso)-polymerase, nicotine amide and thymidine, removed the effect of NAD. The data obtained prompt an assumption that the post-irradiation activation of Ca/Mg-nuclease in thymocytes is associated with the disturbance of its post-translation modification, poly(ADP)ribosylation.
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PMID:[Role of a disorder in poly(ADP-ribosylation) in the activation of Ca/Mg-dependent endonuclease]. 647 18

The cellular basis for the enhanced sensitivity to ionising radiation and some DNA damaging chemicals in ataxia-telangiectasia (AT) cells is not clearly understood. Abnormalities in cell-cycle traverse, chromosome stability and DNA synthesis patterns have suggested that a chromatin associated defect may be the primary lesion in AT. This study involves an attempt to define such an anomaly by the use of a vital DNA specific bis-benzimidazole dye (Hoechst 33342) and deoxyribonuclease II as probes for chromatin organisation in intact and permeabilised human cells respectively. Despite similar DNA binding characteristics (determined by flow cytometry) of Ho33342 in normal and AT transformed fibroblasts, the AT cells show: (i) enhanced cell killing and increased accumulation of cells in G2 phase of the cell-cycle [both biological responses being relatively resistant in AT cells to modification by an inhibitor of poly (ADP ribosyl)ation], (ii) no resistance of de novo DNA synthesis to Ho33342-induced inhibition, (iii) elevated levels of slow-rejoining ligand-induced DNA strand-breaks, and (iv) enhanced expression of chromatin regions accessible to an exogenously supplied endonuclease. The results are interpreted on the basis that a chromatin anomaly of enhanced nuclease susceptibility, involving a minor fraction of the genome, may be a controlling factor in the expression of the various in vivo and in vitro characteristics of AT cells.
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PMID:Relationship between a chromatin anomaly in ataxia-telangiectasia cells and enhanced sensitivity to DNA damage. 648 55

The oligonucleotides A5'pp5'A2'p5'A2'p5'A and A5'ppp5'A2'p5'A2'p5'A were prepared by reaction of AMP or ADP, respectively, with the 5'-(phosphoimidazolidate) of A2'p5'A2'p5'A. A5'pppp5'A2'(p5'A)n (n = 1-3) were synthesized by reaction of p5'A2'(p5'A)n (n = 1-3) with adenosine 5'-trimetaphosphate. All structures were confirmed by enzyme digestion and 1H and 31P nuclear magnetic resonance (NMR). The products A5'pppp5'A2'p5'A and A5'pppp5'A2'p5'A2'p5'A were found to be identical with two of the products of the 2-5A synthetase catalyzed reaction of Ap4A with ATP, thus confirming the structural assignments made by earlier investigators. In extracts of mouse L cells programmed with encephalomyocarditis virus RNA, A5'pppp5'A2'p5'A2'p5'A2'p5'A and A5'pppp5'A2'p5'A2'p5'A were equipotent with 2-5A itself as inhibitors of translation. The oligomers A5'ppp5'A2'p5'A2'p5'A and A2'pppp5'A2'p5'A were about 100 times less active than 2-5A, and A5'pp5'A2'p5'A2'p5'A was without translational inhibitory activity. When affinity for the 2-5A-dependent endonuclease was determined (by displacement of 2-5A[32P]pCp from endonuclease), all of the analogues, as well as 2-5A itself, had similar affinities for the endonuclease except for A5'pppp5'A2'p5'A, which was bound approximately 100 times less effectively. Under conditions of the radiobinding assay, A5'pppp5'A2'p5'A2'p5'A was degraded (t1/2 = 2 h) to ATP, ADP, AMP, ppp5'A2'p5'A2'p5'A, and p5'A2'p5'A2'p5'A.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Synthesis and biological activity of 5'-capped derivatives of 5'-triphosphoadenylyl(2'----5')adenylyl(2'----5')adenosine. 671 21

A new bacteriophage T4-induced DNA-dependent ATPase-endonuclease was purified to essential homogeneity from an extract of late infected Escherichia coli. Both DNA-dependent ATPase and endonuclease activities co-chromatograph, co-sediment, and have been renatured from a single 43-kilodalton protein eluted following sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting that both activities are exerted by one multifunctional protein. Duplex, single-stranded, and supercoiled DNAs are all effective activators of the high specific activity ATPase which produces ADP and inorganic PO4. The enzyme displays a broad specificity towards the nucleoside and deoxynucleoside triphosphates, and the ATPase activity is strongly inhibited by DNA-intercalating compounds. The endonuclease appears to be most active on supercoiled DNA, producing double-stranded breaks in duplex DNA, and does not require nucleoside triphosphates. An antiserum against the purified enzyme immunoprecipitated it, inhibited its ATPase activity, and also precipitated from extracts a T4-induced protein of Mr = 43,000. This antigen was not found in uninfected E. coli, or following a gene 55am mutant (late protein synthesis defective) infection, and was not detected following infection with T4 amber mutants of any early capsid protein gene which blocks T4 head protein cleavage in vivo. In a pulse-chase experiment, the radioactive antigen was not found following a pulse of radioactive amino acids, but appeared after a chase with excess nonradioactive amino acids. The enzyme-related antigen is apparently produced by cleavage of a precursor by the T4 head assembly proteinase which processes a number of prohead proteins. These processing reactions are dependent in vivo upon assembly of the prohead and are required for its maturation. The evidence suggests that this enzyme functions in head assembly and DNA packaging, and originates as the cleavage product of a prohead precursor protein.
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PMID:A bacteriophage T4 DNA packaging related DNA-dependent ATPase-endonuclease. 681 74

Regression of the rat ventral prostate occurs when the level of 5 alpha-dihydrotestosterone, the trophic hormone, drops below the threshold required to suppress apoptosis. The induction of apoptosis in the ventral prostate is accompanied by the increase in the steady-state level of a number of mRNAs coding for proteins that are involved in the latter stages of apoptosis and thus represent secondary thanatogens. These include proteases (cathepsins, plasminogen activators, and collagenase), clusterin, poly(ADP)ribose polymerase, tenascin, and several unidentified genes, as well as several RNases and the classical Ca2+,Mg(2+)-dependent endonuclease. In addition, insulin-like growth-factor-binding protein 5 (IGFBP-5) is induced de novo. We propose that IGFBP-5 may serve to trigger the apoptotic process through the attenuation of the insulin-like growth factor signalling system (which is necessary for cell survival), and as such, represents a primary thanatogen in the prostate.
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PMID:The role of growth factors in the suppression of active cell death in the prostate: an hypothesis. 754 88

A 0.6 kb cDNA fragment encoding the human NAD(+)-specific isocitrate dehydrogenase alpha-subunit (H-IDH alpha) was amplified by PCR using oligonucleotide primers synthesized on the basis of pig tryptic peptide sequences [Huang and Colman (1990) Biochemistry 29, 8266-8273]. With the amplified cDNA as a probe, cDNA clones for IDH alpha were isolated from a human heart lambda gt11 cDNA library. The deduced protein sequence of the largest cDNA clone (2628 bp) rendered a precursor protein of 366 amino acids (39,591 Da) and a mature protein of 339 amino acids (36,640 Da). The deduced H-IDH alpha protein sequence is highly similar to the partial peptide sequences of the pig enzyme. It is 55, 43 and 44% identical with yeast NAD(+)-specific IDH2, yeast NAD(+)-specific IDH1 and monkey NAD(+)-specific IDH gamma-subunit (IDH gamma) respectively. However, it has less similarity (about 30%) to NADP(+)-specific IDH from Escherichia coli and bovine mitochondria. These results indicate that the structure of IDH alpha closely resembles that of IDH2, the catalytic subunit of the yeast enzyme. Structural analysis of the deduced H-IDH alpha protein revealed that the amino acids responsible for the binding of isocitrate, Mg2+ and NAD+ are highly conserved. It also has two conserved motifs for the binding sites of ATP and ADP, but a canonical Ca(2+)-binding motif was not recognized. Unusual penta-(ATTTA) and tri-(TAA or ATT) nucleotides which are respectively believed to interact with RNA-binding proteins and be near the endonuclease cleavage sites were frequently recognized in its 3' untranslated region, indicating the possibility of an additional method of regulation of this enzyme. Northern-blot analysis suggests that one mRNA transcript (2.8 kb) exists in cultured HeLa cells. Genomic DNA Southern-blot analysis indicates that the IDH alpha gene is not closely related to that of the other IDH isoenzymes, and IDH alpha appears to be encoded by a single gene.
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PMID:Characterization of a cDNA clone for human NAD(+)-specific isocitrate dehydrogenase alpha-subunit and structural comparison with its isoenzymes from different species. 775 89

Reactive oxygen species are used to eradicate malignant cells in photodynamic therapy as well as in other cancer therapies. Despite many efforts, the pathways leading to cellular damage and cell killing due to the action of these species are poorly understood. In previous studies with hematoporphyrin derivative-sensitized L929 murine fibroblasts, the only parameter for which a relation with photodynamically induced reproductive cell death could not be excluded was inhibition of DNA excision repair. The present results show that loss of clonogenicity of these cells in fact is related to a series of effects, including the development of slight, irreperable DNA damage, a virtually complete inhibition of poly(ADP-ribosyl)ation activation, a transient elevation of the intracellular calcium concentration and, after a lag time of about 8 h, DNA fragmentation caused by endonuclease activity. This conclusion is supported by the observation that photodynamic treatment inhibited the repair of X-ray-induced DNA strand breaks and suppressed X-ray- and methyl methanesulfonate-induced enhancement of poly(ADP-ribosyl)ation. Our experimental results further suggest that in this cell line the photodynamically induced inhibition of enhanced poly(ADP-ribosyl)ation could well be involved in inhibition of repair of DNA strand breaks and in activation of endonuclease activity.
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PMID:The role of DNA damage and inhibition of poly(ADP-ribosyl)ation in loss of clonogenicity of murine L929 fibroblasts, caused by photodynamically induced oxidative stress. 792 97

Dynamics of the DNA main reparative reactions was studied in rat liver tissue after N-methyl-N-nitrose urea treatment and simultaneous stimulation of NAD biosynthesis in order to evaluate the interrelationship between DNA repair and poly-ADP-ribosylation. Treatment of liver tissue with the mutagen was followed by the preparations incubation in Hanks solution within 30 min at 37 degrees. During the initial steps of restoration an increase in amount of DNA breaks proved to occur in liver tissue of the experimental animals as compared with controls; these deteriorations were decreased down to initial level to the final steps of incubation, while content of breaks in single-strand DNA remained to be high in liver tissue of control animals. The intensive rate of DNA repair in rat liver tissue containing high level of NAD correlated with an increase in nuclear endonuclease and DNA-dependent-DNA-beta-polymerase activities. At the same time, the activity of poly-ADP-ribosyl polymerase was only slightly altered during all the steps of the tissue repair studied.
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PMID:[Study of the dynamics repair of DNA damage caused by N-methyl-N-nitrosourea during activated NAD biosynthesis in rat liver]. 797 85

The bacteriophage lambda terminase is composed of two subunits, gpNu1 and gpA. In vitro, the holoenzyme is a site-specific endonuclease, helicase, ATPase, and can package lambda DNA into proheads. gpA possesses ATPase and helicase activities which are similar to those of the holoenzyme. Both terminase and gpA can hydrolyze a wide range of deoxyribo- and ribonucleoside triphosphates to inorganic phosphate and the corresponding diphosphate. Nucleoside diphosphates are not substrates for either protein. ATPase of both proteins is stimulated by double-stranded DNA. The ATPase of gpA is protein concentration-dependent, while that of terminase is not. Helicase activity of both proteins is not concentration-dependent, and requires a hydrolyzable triphosphate. ATP, dATP, and GTP supported helicase activity, while adenosine 5'-(beta, gamma-methylene)triphosphate, adenosine 5'-3-O-(thio)triphosphate, ADP, CTP, and UTP did not. The kinetic parameters of ATPase and helicase activities were similar for both proteins, but packaging with terminase was optimal only at a significantly higher level of ATP. Packaging was detectable at significant levels with CTP and UTP, but not with GTP. Packaging also differed from ATPase and helicase in the utilization of divalent metal cations and susceptibility to various inhibitors.
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PMID:The in vitro ATPases of bacteriophage lambda terminase and its large subunit, gene product A. The relationship with their DNA helicase and packaging activities. 817 94

Terminases are enzymes common to all of the complex double-stranded DNA viruses and are required for viral assembly. These enzymes function to excise a single viral genome from a concatemeric DNA precursor and package it into a preformed protective protein shell or capsid. ATP hydrolysis by these enzymes has been described and appears to be critical to the packaging process. We have previously characterized the endonuclease activity of purified terminase from bacteriophage lambda [Tomka, M. A., & Catalano, C. E. (1993) J. Biol. Chem. 268, 3056-3065], and we describe here a kinetic characterization of the ATPase activity of the enzyme. lambda Terminase possesses a DNA-stimulated ATPase activity and hydrolyzes ATP to ADP and Pi. This activity requires divalent metal and is supported by all of the group IIa metals examined, as well as Mn2+. The reaction is also stimulated by NaCl, GTP, and dGTP. Of note is that neither of the guanosine nucleotides is hydrolyzed by the enzyme, while dATP is hydrolyzed at a rate comparable to that of ATP. Kinetic analysis of the ATPase activity revealed two apparent binding sites for ATP hydrolysis. The high-affinity site (Km = 5 microM) and low-affinity site (Km approximately 1.3 mM) hydrolyze ATP with kcat = 3 and 16 min-1, respectively. While the high-affinity site is unaffected by the presence of DNA, ATP hydrolysis at the low-affinity site is stimulated by DNA, which results from both a decrease in the Km and a concomitant increase in the kcat of the reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Kinetic characterization of the ATPase activity of the DNA packaging enzyme from bacteriophage lambda. 821 75


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