• KSBB Journal
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• v.13 no.6
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• pp.669-674
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• 1998

This study was carried out particularly focusing on he antitumor effect in combination with 5-fluorocytosine(5-FC), antifungal agent, and extracellular cytosine deaminase from Chromobacterium violaceum YK 391 against U-937, K-562 and SNU-C4 cells. While the addition of 10$\mu\textrm{g}$/100 ${\mu}\ell$ of anticancer agent, 5-fluorouracil(5-FU), to U-937, K-562 and SNU-C4 caused the decrease of proliferation 90%, 75% and 93% respectively, the addition of 20 $\mu\textrm{g}$/100 ${\mu}\ell$ of the extracellular cytosine deaminase and 10 $\mu\textrm{g}$/100 ${\mu}\ell$ of antifungal agent 5-FC caused the decrease of proliferation 80%, 70% and 90%, respectively. These results, therefore, reveal that this enzyme has the similar clinical effect for considering of adjuvant antitumor effect. From the above results, the treatment of 5-FC and the cytosine deaminase was very effective and showed the possibility to remove side effects which easily occur by the treatment of 5-FU only. An extracellular cytosine deaminase.

• Korean Journal of Microbiology
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• v.22 no.4
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• pp.257-263
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• 1984

A strain producing an extracellular cytosine deaminase was isolated from soil samples. The enzyme obtained from the strain possessed the substrate specificity to both cytosine and 5-fluorocytosine. From the results of its morphological, cultural, physiological, and biochemical properties, the strain was thought to be the genus Arthrobacter. Therefore, it was named as Arthrobacter sp. JH-13. The composition of optimum medium for the enzyme formation was 0.5% of peptone, 0.5% of meat extract, 0.5% of soluble starch, and 0.1% of KCl. The optimum pH for the enzyme formation was 8.0. When the microoganism was cultured aerobically in the above medium, enzyme production reached at maximum in 54 hours at $30^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.2
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• pp.179-186
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• 1991

The nutritional requirement and cultural condition such as carbon and nitrogen sources, cultural temperature, initial pH, cultural time and aeration for the production of endocellular cytosine deaminase from Aspergillus fumigatus IFO 5840 were investigated. The cultural broth giving maximum cytosine deaminase yield was found to consist of 2% glucose as a carbon source and 1% yeast extract and 0.1% peptone as a nitrogen source. Optimal initial pH of the culture broth was pH 8.5 and the enzyme production in the cell usually reached a maximum after 28 hours of cultivation in the 500ml shaking flask containing 100ml broth at $30^{\circ}C$. The endoenzyme production of the used strain was inhibited by inorganic nitrogen, but activated by orgainc nitrogen, yeast extract.

• 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.

• Toxicological Research
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• v.6 no.1
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• pp.29-40
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• 1990

Cytotoxic effects of cytosine arabinoside and vinblastine on cultured fibroblasts were determined by colorimetric assays of neutral red (NR) and tetrazolium MTT, and by mutagenicity tests . Cytosine arabinoside and vinblastine were highly toxic by showing that concentrations of NR-50 and MTT-50 of two drugs were lower than 100 ${\mu}$M. At mid-point cytotoxicityvalue of two drugs, frequencies of micronuclei and SCEs were very high and chromosome showed structural abnormalities. The sizes of micronuclei formed by vinblastine were larger than those induced by cytosine arabinoside. These results suggest that cytosine arabinoside and vinblastine have highy mutagenic and severe cytotoxic effects on the cultured mouse fibroblasts.

• 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.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.368-374
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• 1988

Enzymological proprties of an extracellular cytosine deaminase from Bacellus polymyxa YL 38-3 were investigated. The extracellular enzyme was very stable, and optimum pH and temperature for the enzyme activity were found to be near pH 6.0 in 0.2M potassium phosphate buffer and at $30^{\circ}C$, respectively. 5-Fluorocytosine was converyed to 5-fluorouracil by the enzyme, but 5-methylcytosine was not to thymine by it. The enzyme activity was completely inhibited by some heavy metal ion such as 1mM of $Cd^{2-}$ and $Hg^{2+}$, and by 1mM of p-chloromercuribenzoate, respectively. The enzyme activity was inactivated about 75% by 1mM of o-phenanthroline and monoiodoacetate. But the enzyme activity was stimulated up to 200% by 1mM of 2-mercaptoethanol.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.173-178
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• 1999

The extracellular cytosine deaminase (EC 3.5.4.1) from Chromobacterium violaceum YK 391 was purified 264.7-fold with an overall yield of 14.3%. The enzyme was for the first time homogeneous by the criteria of polyacrylamide gel electrophoresis performed in the absence and in the presence of sodium dodecyl sulfate. The molecular weight of the purified enzyme was estimated to be about 156 kDa. The enzyme consisted of two identical subunits of approximate molecular weight 78 kDa. The isoelectric point of the enzyme was pH 5.55. The enzyme had a pH optimum of 7.5 and a temperature optimum of around 40 to $45^{\circ}C$. Besides cytosine, the enzyme deaminated 5-fluorocytosine, cytidine, 5-methylcytosine, and 6-azacytosine, but not 5-azacytosine. The extracellular cytosine deaminase is believed to be unique because it was active not only on cytosine but also on cytidine. The apparent $K_m$ values for cytosine, 5-fluorocytosine, cytidine, and 5-methylcytosine were determined to be 1.55 mM, 5.52 mM, 10.4 mM, and 67.2 mM, respectively. The enzyme activity was strongly inhibited by heavy metal ions such as $Fe^{2+},Pb^{2+},Cd^{2+},Zn^{2+}, Hg^{2+}, and Cu^{2+}$ at 1 mM, and completely by $\alpha,\alpha$'-dipyridyl, and $\rho$-chloromercuribenzoate at 1 mM, and weakly inhibited by 1mM ο-phenanthroline. The enzyme activity was not affected by various nucleosides and nucleotides.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.581-587
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• 1998

Essential amino acids involved in the catalytic role of the extracellular cytosine deaminase from Chromobacterium violaceum YK 391 were determined by chemical modification studies. The enzyme activity required the reduced form of Fe (II) ion, since the enzyme was inhibited by ο-phenanthroline. The enzyme activity was completely inhibited by the chemical modifiers, such as p-chloromercuribenzoate (p-CMB), p-hydroxymercuribenzoate, and chloramine-T at 1 mM each. The enzyme activity was also markedly inhibited by pyridoxal-5'-phosphate, diethyl pyrocarbonate, and phenylmethylsulfonyl fluroride at 1 mM each. The inactivation of the enzyme activity with p-CMB was reversed by a high concentration of cytosine. Furthermore, the inactivation of the enzyme activity with p-CMB was also reactivated by 1 mM dithiothreitol, 1 mM 2-mercaptoethanol, 1 mM cysteine-HCI, 10% ethyl alcohol, and 10% methyl alcohol. These results suggested that cysteine and methionine residues might be located in or near the active site of the enzyme, while lysine, histidine, and serine residues might be indirectly involved in the enzyme activity.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.3039-3044
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• 2009

We report the first electric field dependence IR spectra of three cytosine tautomers solvated in helium nanodroplets. By using an electric field dependence on the three lowest energy tautomers of cytosine and ab initio calculations, we are able to measure the vibrational transition moment angles (VTMAs), specifically for the $NH_2$ symmetric stretch (SS) mode in this study, with more precision; thus we have reassigned the previous $NH_2$ (SS) VTMA of 74$^{\circ}$ for the C1 tautomer to 85$^{\circ}$, which the latter is in excellent agreement with the ab initio value. Nonplanarity of the three lowest energy tautomers of cytosine has been investigated by measuring the VTMA of each vibrational mode for the tautomers.