Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The restricted ability of deoxyribonuclease I/snake venom phosphodiesterase digestion to liberate deoxyadenosine (dA) nucleotide adducts of polycyclic aromatic hydrocarbons from DNA, first observed by Dipple and Pigott with the bay-region diol epoxide adducts of 7,12-dimethylbenz[a]anthracene, has been observed with the dA adducts of benz[a]anthracene and benzo[c]phenanthrene diol epoxides. The micrococcal nuclease/spleen phosphodiesterase digestion used in the original 32P postlabeling procedure developed by Randerath to determine DNA adducts also failed to liberate dA nucleotide adducts quantitatively. Thus either method can potentially lead to an underestimation of the extent to which dA has been modified in DNA. The two digestion procedures exhibit systematic and mostly opposite stereoselectivity in the pattern of which dA adducts are resistant to digestion, which suggest that these adducts may have preferred orientations within modified DNA that are determined by whether they have the R or S configuration at C-1, the point of attachment between the exocyclic amino group of dA and the hydrocarbon; this in turn is dictated by the configuration about the precursor benzylic epoxide carbon and the cis versus trans nature of epoxide opening during adduct formation.
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PMID:Stereoselective release of polycyclic aromatic hydrocarbon-deoxyadenosine adducts from DNA by the 32P postlabeling and deoxyribonuclease I/snake venom phosphodiesterase digestion methods. 196 69

Site-specifically modified oligonucleotides were obtained in milligram quantities by reacting racemic 3t,4r-dihydroxy-1,2t-epoxy-1,2,3,4-tetrahydrobenzo[c]phenanthrene (B[c]PhDE-2, or anti-B[c]PhDE) with the single deoxyadenosine (dA) residue in the oligodeoxynucleotide d(CTCTCACTTCC). Enzyme digestion of the covalently modified oligonucleotides with the exonuclease spleen phosphodiesterase yielded covalently linked B[ca]PhDE-N6-deoxyadenosyl monophosphate (dAMP) adducts. Comparisons of the reverse phase HPLC retention times and CD spectra of these B[c]PhDE-3'-dAMP mononucleotide adducts, with those of standards derived from the reaction of the enantiomers (+)- and (-)-anti-B[c]PhDE with 3'-dAMP, show that two major oligonucleotide adducts (I and II) were obtained upon reacting racemic anti-B[c]PhDE with d(CTCTCACTTCC). In oligonucleotide adduct I, the lesion is a (+)-trans-anti-B[c]PhDE-N6-dA residue, and in oligonucleotide adduct II it is a (-)-trans-anti-B[c]PhDE-N6-dA residue. These assignments were further confirmed using a standard 32P postlabeling assay of B[c]PhDE-3'-dAMP mononucleotide adducts obtained from the digestion of oligonucleotides I and II by spleen phosphodiesterase. The melting points (Tm) of duplexes of modified oligonucleotides I and II and their natural complementary strands are not affected significantly by the presence of the covalently bound benzo[c]phenanthrenyl residues. Opposite stereoselective resistance to enzyme digestion by the exonucleases snake venom phosphodiesterase and spleen phosphodiesterase is exhibited by the stereoisomeric (+)-trans- and (-)-trans-anti-B[c]PhDE-modified oligonucleotide adducts I and II; these results are consistent with the intercalative insertion of the benzo[c]phenanthrenyl residues on the 5'-side of the modified dA residue in adduct I, and its insertion on the 3'-side of the dA residue in adduct II, as observed in the duplexes by high resolution NMR techniques [Cosman et al. (1993) Biochemistry 32, 12488-12497, and Cosman et all, Biochemistry, in press.
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PMID:Direct synthesis and characterization of site-specific adenosyl adducts derived from the binding of a 3,4-dihydroxy-1,2-epoxybenzo[c]phenanthrene stereoisomer to an 11-mer oligodeoxyribonucleotide. 757 32