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 products of RNA and synthetic polynucleotides degradation by intracellular RNAses Pc1 and Pc2 of the fungus Penicillium claviforme were studied. It was shown that the enzymes possess the endonuclease activity and are not specific for the bases vicinal to the cleaved PDE bonds (EC 3.1.4.23). The increase of binding of the dinucleoside monophosphates by Pc1 and Pc2 dependent on the nucleoside at the 3'-end of the PDE bond is: A greater than C greater than G greater than U. This order is opposite for the rates of these substrates cleavage by the RNAses. A homologous specificity of the intracellular RNAse Pc1 and the extracellular RNAse II of Pen. claviforme has been revealed.
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PMID:[Specificity of intracellular ribonucleases Pc1 and Pc2 of the fungus Penicillium claviforme]. 46 88

In previous work, mutations induced by the (+)-anti diol epoxide of benzo[a]pyrene [(+)-anti-B[a]PDE] were scored in the supF gene of the Escherichia coli plasmid pUB3 [Rodriguez & Loechler (1993) Biochemistry 32, 1759]. pUB3 was reacted with (+)-anti-B[a]PDE and then either (1) transformed immediately into E. coli or (2) heated at 80 degrees C for 10 min prior to transformation. Heating only released a small fraction of adducts (approximately 5%) and did not significantly affect the mutagenic pattern at most sites in supF. However, at the major base substitution hotspot, G115, principally G-->T mutations (87%) were obtained prior to heating, while after heating, G-->T mutations decreased (45%) and G-->A (21%) and G-->C (33%) mutations became more prevalent. One model for this result is that prior to heating a heat-labile adduct at G115 causes one pattern of mutagenesis, but after heating the labile adduct is hydrolyzed to an apurinic site (AP site), which causes a second mutational pattern. To test this, a role for AP sites generated from labile adducts by heating at 80 degrees C for 10 min is investigated. It is shown that when plasmid pUB3 contains 22 (+)-anti-B[a]PDE adducts, 0.6% (or fewer) are converted to AP sites as determined in an assay based upon the action of an AP-endonuclease. In a separate line of investigation not involving (+)-anti-B[a]PDE adducts, mutation frequency (MF) per AP site is estimated. (In these experiments, AP sites were introduced into pUB3 by the classic procedure of heating at 70 degrees C/pH 5.0 to hydrolyze purines.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:AP sites are not significantly involved in mutagenesis by the (+)-anti diol epoxide of benzo[a]pyrene: the complexity of its mutagenic specificity is likely to arise from adduct conformational polymorphism. 768 46

Three chimeric dimer synthons (oeg_t(NH)T, oeg_up(NH)T and oeg_uh(NH)T) containing thymine (t), 5-(1-propynyl)-uracil (up) and 5-(1-hexyn-1-yl)-uracil (uh) PNA units with N-(2-hydroxyethyl)glycine (oeg) backbone were synthesized in solution and incorporated into T20 oligonucleotide analogues, using standard P-amidite chemistry. Insertion of dimer blocks led to destabilization of duplexes with dA20 target. The smallest Tm drops were found for chimeras containing oeg_up(NH)T dimers. Incorporation of the chimeric synthons into the 3'-end of T20 brought about growing resistance to 3'-exonucleolytic (SV PDE) cleavage in the order of oeg_t(NH)T < oeg_up(NH)T < oeg_uh(NH)T. Due to different endonuclease activities of 3'- and 5'-exonucleases applied, placing of five consecutive dimers at the 5'-terminus resulted in a relatively smaller, but also side-chain dependent, stabilization towards the hydrolysis by 5'-exonuclease (BS PDE). Neither exonucleases (SV and BS PDE) nor an endonuclease (Nuclease P1) could hydrolyse the unnatural phosphodiester bond linking the 3'-OH of thymidine to the terminal OH of N-(2-hydroxyethyl)glycine PNA backbone.
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PMID:PNA-DNA chimeras containing 5-alkynyl-pyrimidine PNA units. Synthesis, binding properties, and enzymatic stability. 1460 35

DNA methylation is an important cellular mechanism for controlling gene expression. Whereas the mutagenic properties of many DNA adducts, e.g., those arising from polycyclic aromatic hydrocarbons, have been widely studied, little is known about their influence on DNA methylation. We have constructed site-specifically modified 18-mer oligodeoxynucleotide duplexes containing a pair of stereoisomeric adducts derived from a benzo[a]pyrene-derived diol epoxide [(+)- and (-)-r7,t8-dihydroxy-t9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene, or B[a]PDE] bound to the exocyclic amino group of guanine. The adducts, either (+)- or (-)-trans-anti-B[a]P-N(2)-dG (G*), positioned either at the 5'-side or the 3'-side deoxyguanosine residue in the recognition sequence of EcoRII restriction-modification enzymes (5'-...CCA/TGG...) were incorporated into 18-mer oligodeoxynucleotide duplexes. The effects of these lesions on complex formation and the catalytic activity of the EcoRII DNA methyltransferase (M.EcoRII) and EcoRII restriction endonuclease (R.EcoRII) were investigated. The M.EcoRII catalyzes the transfer of a methyl group to the C5 position of the 3'-side cytosine of each strand of the recognition sequence, whereas R.EcoRII catalyzes cleavage of both strands. The binding of R.EcoRII to the oligodeoxynucleotide duplexes and the catalytic cleavage were completely abolished when G was positioned at the 3'-side dG position (5'-...CCTGG*...). When G* was at the 5'-side dG position, binding was moderately diminished, but cleavage was completely blocked. In the case of M.EcoRII, binding is diminished by factors of 5-30 but the catalytic activity was either abolished or reduced 4-80-fold when the adducts were located at either position. Somewhat smaller effects were observed with hemimethylated oligodeoxynucleotide duplexes. These findings suggest that epigenetic effects, in addition to genotoxic effects, need to be considered in chemical carcinogenesis initiated by B[a]PDE, since the inhibition of methylation may allow the expression of genes that promote tumor development.
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PMID:Effects of benzo[a]pyrene-deoxyguanosine lesions on DNA methylation catalyzed by EcoRII DNA methyltransferase and on DNA cleavage effected by EcoRII restriction endonuclease. 1565 62