Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.5.1.2 (DNA ligase)
 2,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hepatocarcinogenic aromatic amines such as 4-aminoazobenzene derivatives and heterocyclic aromatic amines of cooked food origin were found to be liver-selective cytochrome P450IAZ (CYP1A2) inducers. Each aromatic amine showed different species-specificity among rodent experimental animals in terms of the extent of P450 induction. Carcinogenic susceptibility of an animal to the amine was well correlated with the activity and/or inducibility of CYP1A2 in the animals in the early initiation phase of the carcinogenesis. In hyperplastic nodules of rat liver, expression and induction of CYP1A2 as suppressed, especially in the placental form of glutathione S-transferase-positive foci. Despite the decrease of P450s including CYP1A2 in the rat liver bearing hyperplastic nodules. DNA adducts formed by a carcinogenic aromatic amine increased, as compared to the controls, suggesting that the activity of DNA repair enzyme(s) for the amine-derived DNA adducts might decrease in the hyperplastic nodules of rat liver. Treatment of rats with lead nitrate revealed a pattern of P450 expression in the liver similar to that observed with rats bearing hyperplastic nodules. These findings may provide valuable information on the roles of P450s in carcinogenic susceptibility of animals to aromatic amines and in the carcinogenic process.
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PMID:Induction of cytochrome P450 isoforms by carcinogenic aromatic amines and carcinogenic susceptibility of rodent animals. 758 95

Treatment of plasmid pBR322 with Fe2-(HPTB)(OH)(NO3)4(HPTB = N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopr opane) and H2O2 or O2 and a reductant (dithiothreitol or ascorbate) results in double-stranded cleavage of the plasmid. The linearization of supercoiled pBR322 by this complex is not inhibited by hydroxyl radical scavengers. On the other hand, the linearized pBR322 is efficiently religated by T4 DNA ligase, and the presence of 3'-OH and 5'-OPO3 ends is corroborated by 3'- and 5'-end-labeling studies. These observations indicate that cleavage results from hydrolysis of the DNA-phosphate backbone, which is proposed to occur by nucleophilic attack of the bound peroxide on the phosphodiester. Double-stranded cleavage by the Fe2(HPTB)(OH)(NO3)4/H2O2 adduct preferentially occurs between bp 3489 and 3485 of pBR322.
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PMID:Double-stranded cleavage of pBR322 by a diiron complex via a "hydrolytic" mechanism. 829 May 64

We purified to near homogeneity a previously identified 100 kDa mammalian homologous DNA pairing protein. The purified 100 kDa protein also catalyzed high levels of cell-free homologous DNA recombination activity. This ATP-dependent activity was capable of forming conservative recombinant products between two circular, double-stranded DNA molecules. We were unable to detect any DNA polymerase, DNA ligase, or 5' or 3' exonuclease activity associated with this purified material. The purified 100 kDa protein bound silver nitrate as well as a monoclonal antibody specific for nucleolin. A recombinant protein comprised of the Escherichia coli maltos-ebinding protein fused to the carboxyl-terminal two-thirds of human nucleolin possessed homologous DNA pairing activity. These data indicate that the 100 kDa homologous DNA pairing protein is nucleolin. The observation that nucleolin can carry out homologous DNA strand pairing in vitro raises the prospect that it may function similarly in vivo.
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PMID:Nucleolin promotes homologous DNA pairing in vitro. 1069 34