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)

Virion RNA of poliovirus type 1 has been analyzed for the linkage between genome-protein VPg and the polyribonucleotide chain. Hydrolysis of the linkage with acid or alkali and enzymatic degradation lead to the conclusion that the bond is neither a phosphodiester such as nucleotidyl-(P-O)-serine (or threonine) nor a phosphoramidate such as nucleotidyl-(P-N)-amino acid. VPg-RNA can be iodinated by the Bolton and Hunter reagent [iodinated 3-(4-hydroxyphenyl)propionic acid N-hydroxysuccinimide ester] but not by the chloramine-T or lactoperoxidase procedures, an observation suggesting that VPg does not contain accessible tyrosine. However, VPg can be labeled with [3H]tyrosine in vivo. Hydrolysis of VPg-[32P]pUp with 5.6 M HCl at 110 degrees yielded 32P-labeled O4-(3'-phospho-5'-uridylyl)tyrosine that could be cleaved with micrococcal nuclease to O4-[32P]phosphotyrosine and uridine 3'-[32P]phosphate. These data establish that VPg is linked to the poliovirus genome by a bond between the O4 of tyrosine and the 5'-P atom of the terminal uridylic acid residue. The 5' end of polio genome RNA can now be described as VPg(Tyr-O)-pU-U-A-A-A-A-C-A-G.
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PMID:O4-(5'-uridylyl)tyrosine is the bond between the genome-linked protein and the RNA of poliovirus. 21 3

2-Methoxyaniline (o-anisidine) is a urinary bladder carcinogen in both mice and rats. Since the urinary bladder contains substantial peroxidase activity, we investigated the metabolism of this carcinogen by prostaglandin H synthase (PHS), a prominent enzyme in the urinary bladder, and lactoperoxidase as model mammalian peroxidases. Horseradish peroxidase (HRP)-mediated oxidation of o-anisidine was also determined and compared with the reactions catalyzed by mammalian peroxidases. All three peroxidases oxidized o-anisidine via a radical mechanism. Using HPLC combined with electrospray tandem mass spectrometry, we determined that peroxidases oxidized o-anisidine to a diimine metabolite, which subsequently hydrolyzed to form a quinone imine. Two additional metabolites were identified as a dimer linked by an azo bond and another metabolite consisting of three methoxybenzene rings, which exact structure has not been identified as yet. Using [14C]-labeled o-anisidine, we observed substantial peroxidase-dependent covalent binding of o-anisidine to DNA, tRNA and polydeoxynucleotides [poly(dX)]. The 32P-postlabeling assay (a standard procedure and enrichment of adducts by digestion with nuclease P1 or by extraction into 1-butanol prior to 32P-labeling) was employed as the second method to detect and quantitate binding of o-anisidine to DNA. Using these versions of the 32P-postlabeling technique we did not observe any DNA adducts derived from o-anisidine. The o-anisidine-DNA adducts became detectable only when DNA modified by o-anisidine was digested using three times higher concentrations of micrococcal nuclease and spleen phosphodiesterase (MN/SPD). We found deoxyguanosine to be the target for o-anisidine binding in DNA using poly(dX) and deoxyguanosine 3'-monophosphate (dGp). A diimine metabolite of o-anisidine is the reactive species forming adducts in dGp. The results strongly indicate that peroxidases play an important role in o-anisidine metabolism to reactive species, which might be responsible for its genotoxicity, and its carcinogenicity to the urinary bladder in rodents. The limitation of the 32P-postlabeling technique to analyze DNA adducts derived from o-anisidine as a means to estimate its genotoxicity is discussed.
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PMID:Mechanism of peroxidase-mediated oxidation of carcinogenic o-anisidine and its binding to DNA. 1189 Sep 34