• Title/Summary/Keyword: Chemical cleavage

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DNA Cleavage Induced by the Reaction of Salsolinol with Cu,Zn-Superoxide Dismutase

  • Kang, Jung-Hoon
    • Bulletin of the Korean Chemical Society
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    • v.28 no.12
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    • pp.2329-2332
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    • 2007
  • Salsolinol, endogenous neurotoxin, is known to be involved in the pathogenesis of Parkinson's disease (PD). In the present study, we have investigated the oxidative damage of DNA induced by the reaction of salsolinol with Cu,Zn-SOD. When plasmid DNA incubated with salsolinol and Cu,Zn-SOD, DNA cleavage was proportional to the concentrations of salsolinol and Cu,Zn-SOD. The salsolinol/Cu,Zn-SOD system-mediated DNA cleavage was significantly inhibited by radical scavengers such as mannitol, ethanol and thiourea. These results indicated that free radicals might participate in DNA cleavage by the salsolinol/Cu,Zn-SOD system. Spectrophotometric study using a thiobarbituric acid showed that hydroxyl radical formation was proportional to the concentration of salsolinol and was inhibited by radical scavengers. These results indicated that hydroxyl radical generated in the reaction of salsolinol with Cu,Zn-SOD was implicated in the DNA cleavage. Catalase and copper chelators inhibited DNA cleavage and the production of hydroxyl radicals. These results suggest that DNA cleavage is mediated in the reaction of salsolinol with Cu,Zn-SOD via the generation of hydroxyl radical by a combination of the oxidation reaction of salsolinol and Fenton-like reaction of free copper ions released from oxidatively damaged SOD.

Solid-Phase Synthesis of Unfunctionalized Arenes Via the Traceless Cleavage of Sulfonate Linkers

  • Kim, Chul-Bae;Cho, Chul-Hee;Jo, Min-Jy;Park, Kwang-Yong
    • Bulletin of the Korean Chemical Society
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    • v.32 no.10
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    • pp.3655-3659
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    • 2011
  • The hydrogenolysis of polymer-bound arenesulfonates by 2-propylmagnesium chloride was performed through reductive cleavage of the C-S bond in the presence of a nickel catalyst. The reaction underwent in the highest efficiency by adding 15 equiv of the nucleophile in two additions with $dppfNiCl_2$ in THF. Various unfunctionalized naphthalene, biphenyl, and stilbene derivatives were produced in good yields by the traceless sulfonate linker system at room temperature.

Theoretical Studies on the Methanolysis of a Cephalosporin; Mimicking Acylation of the Active Site Serine of D-Ala-D-Ala Transpeptidases

  • Nahm, Kee-Pyung
    • Bulletin of the Korean Chemical Society
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    • v.12 no.6
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    • pp.674-678
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    • 1991
  • Methanolysis of a ${\beta}$-lactam ring of a cephalosporin was simulated with AM1 semiempirical quantum mechanical calculation. The tetrahedral intermediate TD1 from an O-protonated cephalosporin and a methanol transfers the proton intramolecularly to the C-4 carboxylate to generate an oxyanion, i.e., second tetrahedral intermediate TD2, which undergoes the amide bond cleavage without further protonation on the N-5. For this cleavage a low-energy barrier TS2 was located. According to the energy diagram, tetrahedral intermediates easily undergo ring cleavage even without the protonation on the amide nitrogen.