• Archives of Pharmacal Research
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• v.10 no.2
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• pp.110-114
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• 1987

To correlate the conformational changes of DNA (Calf Thymus) with entrapment of DNA into liposomes, the effect of ions ($Na^+$, $Mg^{++}$on the entrapment of calf thymus DNA into liposomes was investigated. The effect of divalent ion ($Mg^{++}$ on the structural changes of DNA indicated by decrease of observed ellipticity at 274 nm and nonspecific binding of DNA to lipid bilayers was greater than monovalent ion ($\Na^+$). But the efficiency of DNA encapsulated was not altered. These results show that entrapment of DNA into liposomes is not due to nonspecific binding and structural changes because of electrostatic forces but to mechanical capture of DNA by the internal aqueous space of liposomes although divalent ion contributes large structural changes and more nonspecific association of DNA with liposomes due to strong charges.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.429-433
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• 1983

Spermine has opposite effect on the susceptibility of native and denatured calf thymus DNA toward deoxyribonuclease Ⅰ (DNase I; deoxyribonucleate 5'-oligonucleotidohydrolase; EC 3.1.4.5; from bovine pancreas). It enhances the susceptibility of the native DNA, whereas depresses that of the denatured DNA. In the absence of spermine, the reactivity of the deoxyribonuclease is apparently insensitive to the conformational difference of the native and denatured DNA.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2309-2317
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• 2009

Depurination, the release of purine bases from nucleic acids by hydrolysis of the N-glycosidic bond, gives rise to alterations of the cell genome. Though cells have evolved mechanisms to repair these lesions, unrepaired apurinic sites have been shown to have two biological consequences: lethality and base substitution errors. 2-Bromopropane (2-BP) is used as an intermediate in the synthesis of pharmaceuticals, dyes, and other organics. In addition, 2-BP has been used as a replacement for chloroflurocarbons and 1,1,1-trichloroethane as a cleaning solvent in electronics industry. However, 2-BP was found to cause reproductive and hematopoietic disorders in local workers exposed to it. Owing to the toxicity of 2-BP, there has been a tendency to use 1-BP as an alternative cleaning solvent to 2-BP. However, 1-BP has also been reported to be neurotoxic in rats. Though $N^7$-guanine adduct of 2-BP has been reported previously, massive depurination of the nucleosides and calf thymus DNA was observed in this study. We incubated the nucleosides (ddG, dG, guanosine, ddA, dA and adenosine) with excess amount 2-BP at the physiological condition (pH 7.4, $37\;{^{\circ}C}$), which were analyzed by HPLC and LC-MS/MS. In addition, the time and dose response relationship of depurination in nucleosides induced by 2-bromopropane at the physiological condition was investigated. Similarly, incubation of calf-thymus DNA with the excess amount 2-BP at the physiological condition was also performed. In addition, the time and dose response relationship of depurination in calf-thymus DNA induced by 2-BP at the physiological condition was investigated. Those results suggest that the toxic effect of 2-BP could be both from the depurination of nucleosides and DNA adduct formation.

• Environmental Mutagens and Carcinogens
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• v.18 no.2
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• pp.77-82
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• 1998

In order to compare the suppressive effect of galangin on the genotoxicity by N-methyl-N-nitrosourea (MNU) or benzo[a]pyrene B(a)P, in vivo micronycleus test using mouse peripheral blood and in vitro sister chromatid exchange(SCE) test using mouse spleen lymphocytes were performed. MNU or B(a)P-induced micronucleated reticulocytes in vivo was decreased by the simultaneous treatment of galangin. MNU or B(a)P-induced SCEs in vitro was also decreased by the simultaneous treatment of galangin. On the other hand, the determinations of [$^3$H]MNU-induced total DNA binding and methylated DNA were performed to find out the mechanism of action. [$^3$H]MNU-induced total DNA binding was inhibited by the treatment of galangin in calf thymus DNA. HPLC analysis of DNA hydrolysates showed that galangin caused a decrease of 7-methyl guanine and $O^{6}$-methyl guanine in calf thymus DNA. To elucidate the action mechanism of galangin against B(a)P, alteration of B(a)P metabolism was studied. Galangin inhibited B(a)P metabolism in the presence of S-9 mix and decreased B(a)P-DNA binding in calf thymus DNA with S-9 mix.

• Journal of the Korean Chemical Society
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• v.28 no.3
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• pp.185-193
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• 1984

At the spermine concentration to cover the number of the binding site of spermine 0.016 per nucleotide, the Hill coefficient of the ethidium binding to the calf thymus DNA was 1.7, while the value was 0.38 in the absence of the spermine. On the basis of the data, together with other present data on the viscometric titration of the DNA with spermine and anomalous absorbance-temperature profile at 260nm and viscosity-temperature profile, it can be speculated that allosteric propagation of the conformational transition induced by the binding of the spermine may be involved in the monomolecular collapse of the DNA to a condensed structure.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.262-264
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• 1991

An anomalous absorbance-temperature profile of calf thymus DNA, having a hypochromic trough just before the rise the $T_m$-region phase, occurs at the spermine concentration where the DNA collapses into a compact structure. The trough phase can be eliminated by the addition of ethidium bromide and also by a hydrophobic environment.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.191-195
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• 2000

Quantitation of N7-methyldeoxyguanosine (N7-MedG) produced in the in vitro N-methly-N-nitrosuourea (NMU) action on thymus DNA has been achieved by enzymatic degradation, liquid chromatoraphic separaphic separation and desorption chemical ionization tandem mass spectrometry. In conjunction with the resolving power HPLC in the separation of isomers, desorprion chemical ionization tandem mass spectrometry has utilized in determining modified nucleosides at low levels using a stable-isotope labled compound as an internal reforence. The quantitative estimation of N7-methyldeoxyguanosine was previously established by an independent HPLC analysis of methylated calf thymus DNA. A sensitive and specific methodogy for the quantitation of N7-MedG at the picomole level using HPLC combined with tandem mass spectrometry without radioisotope labeling process is presented. The potential of the liquid chromatoraphic tandem mass exposure to methlation agents in vitro.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2318-2328
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• 2009

Massive deadenylation of adenine based-nucleosides induced by halogenated alkanes at the physiological condition have been observed. For the study of deadenylation effects by the different substituents and/or functionality in halogenated alkanes, diverse kinds of halogenated alkanes were incubated with adenine based-nucleosides (ddA, dA and adenosine) for 48 h at the physiological condition (pH 7.4, $37\;{^{\circ}C}$), which were analyzed by HPLC and further confirmed by LC-MS. Among the sixteen different halogenated alkanes, we observed massive deadenylation of nucleosides by 2-bromo-2-methylpropane, 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane. The order of deadenylation rate was highest in 2-bromo-2-methylpropane followed by 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane. In addition, time and dose response relationship of deadenylation in adenine based-nucleosides induced by 2-bromo-2-methylpropane, 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane at the physiological condition were investigated. In addition, deadenylation of calf thymus DNA induced by halogenated alkanes was also investigated. These results suggest that the toxic effect of certain halogenated alkanes might be from the depurination of nucleosides.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2949-2958
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• 2009

Massive deguanylation of guanine based-nucleosides induced by halogenated alkanes at the physiological condition have been observed. For the study of deguanylation effects by the different substituents and/or functionality in halogenated alkanes, diverse kinds of halogenated alkanes were incubated with guanine based-nucleosides (ddG, dG and guanosine) for 48 h at the physiological condition (pH 7.4, 37$^{\circ}C$), which were analyzed by HPLC and further confirmed by LC-MS. Among the sixteen different halogenated alkanes, we observed massive deguanylation of nucleosides by 2-bromo-2-methylpropane, 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane. The order of deguanylation rate was highest in 2-bromo-2-methylpropane followed by 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane. In addition, time and dose response relationship of deguanylation in guanine basednucleosides induced by 2-bromo-2-methylpropane, 2,3-dibromopropene, 2-bromopropane, bromoethane and 2-iodopropane at the physiological condition were investigated. Deguanylation of calf thymus DNA induced by halogenated alkanes was also investigated. These results suggest that the toxic effect of certain halogenated alkanes might be from the depurination of nucleosides.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.87-89
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• 2001