• Journal of Microbiology and Biotechnology
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• v.32 no.8
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• pp.1041-1046
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• 2022

Nucleoside deoxyribosyltransferase (NDT) is an enzyme that replaces the purine or pyrimidine base of 2'-deoxyribonucleoside. This enzyme is generally used in the nucleotide salvage pathway in vivo and synthesizes many nucleoside analogs in vitro for various biotechnological purposes. Since NDT is known to exhibit relatively low reactivity toward nucleoside analogs such as 2'-fluoro-2'-deoxynucleoside, it is necessary to develop an enhanced NDT mutant enzyme suitable for nucleoside analogs. In this study, molecular evolution strategy via error-prone PCR was performed with ndt gene derived from Lactobacillus leichmannii as a template to obtain an engineered NDT with higher substrate specificity to 2FDU (2'-fluoro-2'-deoxyuridine). A mutant library of 214 ndt genes with different sequences was obtained and performed for the conversion of 2FDU to 2FDA (2'-fluoro-2'-deoxyadenosine). The E. coli containing a mutant NDT, named NDT^L59Q, showed 1.7-fold (at 40℃) and 4.4-fold (at 50℃) higher 2FDU-to-2FDA conversions compared to the NDT^WT, respectively. Subsequently, both NDT^WT and NDT^L59Q enzymes were over-expressed and purified using a His-tag system in E. coli. Characterization and enzyme kinetics revealed that the NDT^L59Q mutant enzyme containing a single point mutation of leucine to glutamine at the 59^th position exhibited superior thermal stability with enhanced substrate specificity to 2FDU.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.193-194
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• 1991

The purine nucleoside, adenosine, mp. $223-4^\circ$, was isolated from the rhizomes of Polygonatum sibricum. Its structure was characterized on the basis of spectral data.

• Archives of Pharmacal Research
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• v.6 no.1
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• pp.79-81
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• 1983

Several potent anti-herpes virus nucleosides, 2'fluoro-2'-deoxyarabinofuranosyl pyrimidine nucleosides, were prepared in good yields by a new condensation method using sodium iodide and a new solvent system, and FMAU could be also prepared directly from thymine by this method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.3
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• pp.286-290
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• 1992

From the leaves of Allium tuberosum (Liliaceae), . the purine nucleoside, adenosine was isolated and its structure was characterized on the basis of spectral data. Besides this nucleoside, the composition and relative content of free amino acids and related compounds, compared to standards determined under identical conditions was also investigated using automatic amino acid analyzer. Major free amino acids were alanine, glutamic acid, aspartic acid and valine.

• Journal of Pharmaceutical Investigation
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• v.36 no.4
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• pp.283-286
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• 2006

The present study aimed to investigate the interaction of nucleoside analogs with human organic anion transporter 1 and 3(hOAT1 and hOAT3) that play a primary role in the tubular uptake of endogenous and exogenous organic anions in the kidney. The interactions of ddC, ara-C, ara-A and ara-U with hOAT1 and hOAT3 were examined using MDCK cells stably overexpressing hOAT1 or hOAT3. Among the tested drugs, ddC showed the highest affinity to hOAT1 with $IC_{50}$ values of 5.2 mM, while ara-A, ara-C and ara-U weakly inhibited the cellular uptake of $[^3H]-PAH$ in MDCK-hOAT1 cells at 1 mM. In contrast, all the tested drugs did not have any inhibition effect on the cellular uptake of $[^3H]-estrone$ sulfate in MDCK-hOAT3 cells over the drug concentration of 0.01-2 mM, implying that they might not interact with hOAT3. Taken all together, the present study suggests that hOAT1 could weakly interact with nucleoside analogues such as ddC, ara-C, ara-A and ara-U but the interaction with hOAT3 during the urinary excretion of these nucleoside analogues may be negligible in the kidney.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.613-630
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• 2006

Nucleic acids are virtually omnipresent; they exist in every living being. These macromolecules constitute the most important genetic storage material: the genes. Genes are conserved throughout the evolution of all living beings; they are transmitted from the parents to their offspring. Many interdisciplinary research groups are interested in modifying nucleic acids for use in a wider variety of applications. These modified oligonucleotides are used in many diverse fields, including diagnostics, detection, and therapeutics. In this account, we summarize our research efforts related to modified nucleic acid systems. First, we discuss our syntheses of modified oligonucleotides containing fluorescent tags for use as molecular probes (molecular beacons) to detect single-nucleotide polymorphisim (SNP) in nucleic acids and to distinguish between the B and Z forms of DNA. We also describe our research efforts into oligonucleotides functionalized with steroid derivatives to enhance their cell permeability, and the synthesis of several calix[4]arene-oligonucleotide conjugates possessing the ability to form defined triplexes. In addition, we have performed systematic studies to have an understanding about the functional groups necessary for a given nucleoside to behave as an organo or hydrogelator. The aggregation properties of a number of nucleoside-based phospholipids have been examined in different solvents; some of these derivatives are potential candidates for use as nucleoside-based liposomes. Finally, we also describe our research efforts toward the preparation of isoxazole- and isoxazoline-containing nucleoside derivatives and the determination of their antiviral activities.

• Korean Journal of Microbiology
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• v.31 no.2
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• pp.148-156
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• 1993

Kinetic parameters of purine nucleoside phosphorylase (PNP) from Saccharomyces cerevisiae were measured. The Michaelis constants determined for substrates of the enzyme were $ 2.0 * 10^{-4}$ M for inosine, $2.0 *10^{-3}$ M for deoxyinosine, $ 2.0 * 10^{-5}$ M for guanosine and $2.0 10 ^{-5}$ M for deoxyguanosine. According to the ratio of relative $K_{cat}$Km, substrate specificity of each nucleoside was in the order of guanosine or deoxyguanosine, inosine and deoxyinosine. Cosubstrate, phosphate, revealed downward curvature in Lineweaver-Burk plot at high concentrations, indicating a negative cooperativity between subunits. The inhibition constants for purine analogs were measured to be $ 6 * 10^{-4}$ M for formycin B as the competitive inhibitor of inosine, $ 9 * 10^{-6}$ M for guanine as the competitive inhibitor of guanosine, $2 * 10^{-4}$ M for hypoxanthine as the non competitive inhibitor of guanosine and $4.5 * 10 ^{-4}$ M for 6-mercaptopurine as the non competitive inhibitor of guanosine. Alternative substrates, guanosine, deoxyguanosine and adenosine were found to act as competitive inhibitors with Ki values o $f^ 2.0 * 10 {-5}$ M, $2.6 * 10^{-5}$ M and $8.5 * 10 ^{-4}$ M, respectively, when inosine was the variable substrate. Guanosine and deoxyguanosine were also observed as competitive inhibitors with the Ki values of $1.8 * 10^{-5}$ M and $ 3.0 * 10^{-5}$ M, respectively, when deoxyinesine was the variable substrate. The results of alternative substrate sstudies suggested that a single enzyme acted on different nucleosides, inosine, deoxyinosine, adenosine, guanosine and deoxyguanosine.e.

• Korean Journal of Plant Resources
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• v.16 no.3
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• pp.257-263
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• 2003

The NDK1 is an ubiquitous enzyme that transfer phosphate groups from triphosphate nucleoside diphosphates(NDPs) in eukaryotes and prokaryotes. We isolated and characterized a cDNA encoding a nucleoside diphosphate kinase 1(CNDK 1) in Codonopsis lanceolata. The CNDK 1 is 444bp long and open reading frame of 447bp with a deduced amino acid of 148 residue. The CNDK 1 has an ATP binding site in 12­16 residue and phosphohistidine intermediate in 115 residue of amino acid sequence. Although several NDK 1 genes have been cloned in plants, but little is known about the functional significance of this enzyme during plant growth and development. The CNDK 1 shows the identities to Arabidopsis thaliana (71％), Oryza sativa(75％), Glycine max (79％), Brassica rapa (77％), Mesembryanthemum crystallinum (85 ％), Spinacia oleracea (83％), Pisum sativum (82％). The CNDK 1 of C. laceolata have a closer relationship of Glycine max and Pisum sativum at the phylogenic analysis.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.281-284
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• 2014

Immune defense responses against Pseudomonas aeruginosa infection play an important role in maintaining homeostasis in the human body. Previously, we reported that expression of the bradykinin receptor (BR) is induced in response to P. aeruginosa infection. However, the factors responsible for the induction was uncertain. Here, we found that the type III secretion system (T3SS) is responsible for the induction of BR expression, and nucleoside diphosphate kinase (Ndk), as a novel T3SS effector, mediates the upregulation. The Ndk-mediated expression of BR was not induced by fliC mutant treatment, indicating the involvement of flagellin, one of the well-known pathogen-associated molecular patterns (PAMPs). Taken together, this study demonstrated that Ndk cooperates with flagella in the development of defense responses against P. aeruginosa infection.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.17-20
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• 1999

Facile synthetic methods of 2',5'-dideoxy-, 2',3'-dideoxy- and 3'-deoxy-1, N6-ethenoadenosine nucleosides by either an enzymatic dideoxyribosyl transfer reaction or a simple chemical reaction were proposed. The synthesis products were isolated and purified by preparative HPLC and their structures were confirmed by 1H NMR (500 MHz) and FAB-MS including high resolution mass measurement. These modified nucleoside analogs have not been reported yet. Therefore, these modified nucleoside analogs are of potential value to be studied further for biological activity such as anticancer or antiviral.