• Korean Journal of Microbiology
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• v.10 no.1
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• pp.35-40
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• 1972

1) The photodecomposition rate of guanine being catalized by methylene blue ws 53.7% in contrast with 9.3% that of dark control for 180 min. 2) In guanine control, the decomposition rate was very low. For 180 min., the rate was 8.1% in illuminated sample and 3.9% in non-illuminated sample. 3) The decomposition rate of methylene blue was obviously interfered by the existence of guanine. In guanine and methylene blue mixture solution, the net decomposition rate, excluding that of dark control ws 39.2% and in dye only solution, it was 48.5%.

• Bulletin of the Korean Chemical Society
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• v.21 no.7
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• pp.709-711
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• 2000

Oxidizing metal complex mediates the electrochemical oxidation of guanine nucleotides. This catalysis results in an enhancement in cyclic voltammograms that yield the rate constant for the oxidation of guanine by the metal complex via digital simulation. The rate constant of oxidation of guanine by Ru(bpy)3(3+) is 6.4 x 10(5)M(-1)s(-l). The rate constant and the enhanced current depend on the number of phosphate groups on the sugar of nucleotidc. Also the modified guanine bases show different oxidation rate constants following the trend guanine-5'- monophosphatc (GMP) > 8-bromo-guanine-5'-monophosphate (8-Br-GMP) > xanthosine -5'-monophosphate (XMP) > inosinc-5'-monophosphate (IMP). The guanine bases derivatized differently are all distinguishable from one another, providing a basis for studying electrochemistry of DNA and RNA and developing electrochemical biosensors.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.539-547
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• 1990

Molecular Orbital calculations using the SC-MEH method have been carried out for the interaction of Adenine, Guanine and Cytosine as DNA base and diaminecytosineplatinum(DCP) in various conformations. The results showed that the order of DCP binding to the DNA bases was guanine > adenine > cytosine and the stabilization energy of cis-isomer was larger than that of trans-isomer in the adenine-DCP complexes system. Furthermore, platinum(II) binding to DNA bases markedly gives rise to change of atomic charge in DNA bases ring, which can explain anti-tumor activity of platinum complex.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.366-377
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• 1994

The base composition of DNA of Aspergillus phoenicis, Rhizopus acidus and Candida albicans treated with cycloheximide and nalidixic acid during the culture was analyzed to compare with the control. The contents of base in the DNA were inhibited by cycloheximide, 20.4% of adenine, 43.1% of thymine, 40.9% of cytosine, 35.3% of guanine, 32.2% of purine, and 42.7% of pyrimidine for A. phoenicis. In R. acidus, 34.2% of adenine, 42.1% of thymine, 38.0% of cytosine, 18.1% of guanine, 24.1% of purine and 40.0% of pyrimidine were depressed by cycloheximide. In the antibiotic treatment of C. albicans, 58.3% of adenine, 58.5% of thymine, 58.1% of cytosine, 42.4% of guanine, 46.8% of purine and 58.8% of pyrimidine were inhibited to compare with the control. The nalidixic acid treatments were showed that, in A. phoenicis 41.6% of adenine, 47.1% of thymine, 59.3% of cytosine, 46.3% of guanine, 45.6% of purine and 57.2% of pyrimidine were inhibited. When R. acidus was treated with nalidixic acid, 59.1% of adenine, 54.7% of thymine, 35.3% of cytosine, 37.4% of guanine, 45.9% of purine and 44.9% of pyrimidine decreased. In treatment of nalidixic acid, the content of DNA was depressed 60.1% of adenine, 68.6% of thymine, 60.7% of cytosine, 40.0% of guanine, 45.8% of purine and 63.5% of pyrimidine for C. albicans In the DNA synthesis of three fungal cells, cycloheximide and nalidixic acid treatments were analyzed obviously that the biosynthesis of pyrimidine was depressed than that of purine. Therefore, it was showed that the DNA contents in the various fungal cells were inhibited remarkably in nalidixic acid treatment than cycloheximide.

• Journal of the Korean Chemical Society
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• v.16 no.5
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• pp.298-303
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• 1972

The adduct between phenylglyoxal and guanine was prepared. The structure of the adduct is similar to the glyoxal-guanine adduct. Aldehyde group of phenylglyoxal is added to 1-N of guanine base, and keto group is added to $N^2$ of guanine base. The structure of the adduct was determined by mass spectrometry, nuclear magnetic resonance spectroscopy and periodate oxidation. Periodate oxidation produced $N^2$-benzoyl-guanine from the adduct. On the basis of these results, ittvhas been assigned the structure I. The adduct is stable in alkaline solution: It does not dissociate into phenylglyoxal and guanine even after 2 hours heating at$60^{\circ}C$ at pH 12. The adduct is soluble in acidic ethanol, and is slightly soluble in neutral or alkaline water. It has a lower $A_{280}/A_{260}$ ratio at pH 1 compared to that of guanine.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.679-684
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• 1992

New Pd(IV) complexes have been prepared through the reactions of $trans-[Pd(en)_2Cl_2](ClO_4)_2 $(en = ethylenediamine) with Guanine, Adenine, or Uracil anion as purine and pyrimidine base. We identified the ratio of central metal versus ligands by $C{\cdot}H{\cdot}N$ elemental analysis and proposed the coordinating site of the base by infrared spectrum, $^1H-NMR,\; and\; ^{13}C$-NMR spectrum. Guanine or Adenine ligand coordinated at N7 site and an en ligand exchanged for $ClO_4^-$ counter ions of the starting material . As these results, the complexes showed the formula $[Pd(en)L_2(ClO_4)_2](ClO_4)_2{\cdot}(en)$, (L = Guanine, Adenine). But in the Uracil complex no exchange of the en ligand and $ClO_4^-$ occured and Uracil anion preferred the N1 to N3 as coordinating site, the complex $[Pd(en)_2(Urac)_2](ClO_4)_2(Urac = Uracil anion).$

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.610-613
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• 1991

Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The $K_i$ values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 rnM for hypoxanthine and xanthine with $NAD^+$ as the second substrate, respectively, and 0.1 rnM for $NAD^+$ with either hypoxanthine or xanthine as the second substrate.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.109.1-109.1
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• 2015

Understanding the reaction mechanisms and structures underlying the adsorption of biomolecules on semiconductors is important for functionalizing semiconductor surfaces for various bioapplications. Herein, we describe the characteristic behavior of a primary nucleobase adsorbed on the semiconductor Ge(100). The adsorption configuration of guanine, a primary nucleobase found in DNA and RNA, on the semiconductor Ge(100) at an atomic level was investigated using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. When adsorbed on Ge(100) at room temperature, guanine appears dark in STM images, indicating that the adsorption of guanine on Ge(100) occurs through N-H dissociation. In addition, DFT calculations revealed that "N(1)-H dissociation through an O dative bonded structure" is the most favorable adsorption configuration of all the possible ones. We anticipate that the characterization of guanine adsorbed on Ge(100) will contribute to the development of semiconductor-based biodevices.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.151-155
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• 2015

The molecular interactions between the nucleic acid bases and water molecules are important in organism. Despite Adenine-Thymine Hoogsteen base pair and Guanine-Cytosine Watson-Crick base pair have been demonstrated to be most stable in a gas phase, the effect of water on the stability of these base pairs remains elusive. Here we report the structural and thermodynamic characteristics on possible Adenine-Thymine and Guanine-Cytosine base pairs in a gas phase as well as in an aqueous phase by using quantum mechanical method and statistical mechanical calculations. First, we optimized the direct base-pair interaction energies of four Adenine-Thymine base pairs (Hoogsteen base pair, reverse Hoogsteen base pair, Watson-Crick base pair, and reverse Watson-Crick base pair) and three Guanine-Cytosine base pairs (GC1 base pair, GC2 base pair, and Watson Crick base pair) in a gas phase at the $B3LYP/6-31+G^{**}$ level. Then, the effect of solvent was quantified by the electronic reorganization energy and the solvation free energy by statistical mechanical calculations. Thereby, we discuss the effect of water on the stability of Adenine-Thymine and Guanine-Cytosine base pairs, and argue why Adenine-Thymine Watson-Crick base pair and Guanine-Cytosine Watson-Crick base pair are most stable in an aqueous environment.

• Archives of Pharmacal Research
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• v.25 no.1
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• pp.11-24
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• 2002

The antitumor antibiotic (+)-CC-1065 can alkylate N3 of guanine in certain sequences. A previous high-field $^1H$ NMR study on the$(+)-CC-1065d[GCGCAATTG*CGC]_2$ adduct ($^*$ indicates the drug alkylation site) showed that drag modification on N3 of guanine results in protonation of the cross-strand cytosine [Park, H-J.; Hurley, L. H. J. Am. Chem. Soc.1997, 119,629]. In this contribution we describe a further analysis of the NMR data sets together with restrained molecular dynamics. This study provides not only a solution structure of the (+)-CC-1065(N3- guanine) DNA duplex adduct but also new insight into the molecular basis for the sequence- specific interaction between (+)-CC-1065 and N3-guanine in the DNA duplex. On the basis of NOESY data, we propose that the narrow minor groove at the 7T8T step and conformational kinks at the junctions of 16C17A and 18A19T are both related to DNA bending in the drugDNA adduct. Analysis of the one-dimensional $^1H$ NMR (in $H_2O$) data and rMD trajectories strongly suggests that hydrogen bonding linkages between the 8-OH group of the (+)-CC-1065 A-sub-unit and the 9G10C phosphate via a water molecule are present. All the phenomena observed here in the (+)-CC-1065(N3-guanine) adduct at 5'$-AATTG^*$are reminiscent of those obtained from the studies on the (+)-CC-1065(N3-adenine) adduct at $5'-AGTTA^*$, suggesting that (+)-CC-1065 takes advantage of the conformational flexibility of the 5'-TPu step to entrap the bent structure required for the covalent bonding reaction. This study reveals a common molecular basis for (+)-CC-1065 alkylation at both $5'-TTG^*$ and $5'-TTA^*$, which involves a trapping out of sequence-dependent DNA conformational flexibility as well as sequence-dependent general acid and general base catalysis by duplex DNA.