• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.471-475
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• 1990

A thermostable adenylate kinase isolated from the sonic extracts of Thermus caldophilus cells revealed higher substrate-specificity to the nucleoside monophosphate than to the nucleoside triphosphate. A $P', P^5$-di(adenosine-5') pentaphosphate was acted as a competitive inhibitor to the various substrates. Various divalent cations were activated the enzyme activity following orders: $Mg^{2+}, Ca^{2+}, Mn^{2+}, Ba^[2+}, $ and $Fe^{2+}$-. The enzyme activity was not affected by the sulfurhydryl reagent, p-chloromeric uribenzoic acid and activated by addition of the sodium chloride or phosphoenol pyruvate to the reaction mixture.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.411-416
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• 2011

Steric and electronic parameters of 4'-substituents play significant roles in steering the conformation of nucleoside analogues. In order to investigate the relationship of 4'-group with antiviral enhancement, novel 4'-hydroxymethyl-5'-norcarbocyclic adenosine phosphonic acid analogues were designed and synthesized from 2,2-dimethyl-1,3-dioxolane-4-ethanol (5) using reiterative Grignard addition and ring-closing metathesis (RCM) as key reactions. The synthesized adenosine phosphonic acids analogues (22) and (23) were subjected to antiviral screening against HIV-1. Compound (23) exhibited moderate anti-HIV activity ($EC_50$ = 8.61 ${\mu}M$) in the CEM cell line.

• Journal of Integrative Natural Science
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• v.8 no.2
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• pp.99-106
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• 2015

Novel 2'(${\beta}$)-fluoro-3'(${\alpha}$)-hydroxy-threose nucleosides (iso-FMAU) as antiviral agents were designed and racemically synthesized from Solketal. Condensation successfully proceeded from a glycosyl donor 9 under $Vorbr{\ddot{u}}ggen$ conditions yielded the nucleoside analogues. Ammonolysis and hydrolysis of isopropylidene protection group gave the desired nucleoside analogues 12, 15, 18, and 19. The antiviral activities of the synthesized compounds were evaluated against the HIV-1, HSV-1, HSV-2 and HCMV. Compound 12 displayed some anti-HCMV activity ($EC_{50}=24.7{\mu}g/ml$) without exhibiting any cytotoxicity up to $100{\mu}M$.

• Journal of Microbiology
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• v.34 no.3
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• pp.270-273
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• 1996

Micrococcus luteus purine nucleoside phosphorylase (PNP) has been purified and characterized. The physical and kinetic properties have been described previously. Chemical modification of the enzyme was attempted to gain insight on the active site. The enzyme was inactivated in a time-dependent manner by the arginine- specific modifying reagent phenylglyoxal. There was a linear relationship between the observed rate of inactivation and the phenylglyoxal concentration. At 30 $^{\circ}C$ the bimolecular rate constant for the modification was 0.015 $min^{-1}mM^{-1}$ in 50 mM $NaHCO_3$ buffer, pH 7.5. The plot of logk versus log phenylglyoxal concentration was a strainght line with a slope value of 0.9, indicating that modification of one arginine residue was needed to inactivate the enzyme. Preincubation with saturated solutions of substrates protected the enzyme from inhibition of phenylglyoxal, indicating that reactions with phenylglyoxal were directed at arginyl residues essential for the catalytic functioning of the enzyme.

• Journal of Microbiology
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• v.34 no.1
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• pp.82-89
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• 1996

Purine nucleoside phosphorylase (PNP) was purified in Micrococcus luteus (M. luteus) using streptomycin sulfate and amomonium sulfate fractionation, three times by a Sephadex G-100 gel filtration and a DEAE-Sephadex A-50 ion exchange chromatography. The enzyme was purified 72 folds with a 11% recovery and showed a single band in a nondenaturing gel electrophoresis. The M. W. of PNP turned out to be 1.35 * 10$^{5}$ delton in G-150 gel filtration chromatography. The stability of the enzyme was increased by treatment with both substrates, MgCI$_{2}$ or CaCI$_{2}$, but not significantly kcal/mol. M. luteus PNP catalyzed the phosphorolysis of inosine, deoxyinosine, guanosine and deoxyguanosine with the Km value of 1.5 * 10$^{-3}$ M, 3.0 * 10$^{-3}$ M, 5.0 * 10$^{-4}$ M, respectively. The enzyme was reacted with adenosine, 1-methylnosine and 1-methylguanosine as substrates, which were shown to be poor substrates for mammalian enzyme.

• Korean Journal of Microbiology
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• v.29 no.3
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• pp.172-178
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• 1991

Intracellular purine nucleoside phosphorylase (PNP) from Saccharomyces cerevisiae was partially purified using ammonium sulfate fractionation, heat treatment, a DEAE-Sephadex A-50 anion exchange chromatography and a Sephadex G-100 gel filtration chromatography. The enzyme was purified 20 fold with 3% recovery. The stability of enzyme was kept by addition of inosine and dithiothreitol. The pH optimum was found to be from 6.3 to 7.3 PNP was sensitive to 10mM of $Hg^{2+}$ , $Cu^{2+}$ , and was inactivated completely by 2 mM of p-chloromercuribenzoate and 5,5'-dithiobis (2-nitrobenzoate). The enzyme was capable of catalyzing the phosphorolysis of inosine, deoxyinosine, guanosine, deoxyguanosine and adenosine.

• Korean Journal of Microbiology
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• v.29 no.6
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• pp.353-360
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• 1991

5-substituted uridine(I,Br,Cl), 5'-amino-5'-deoxyuridine conjugates of amino acid, peptide and penicillin G, 5'-monophosphate uridine derivatives and 5'-monophosphate-fatty acid detrivatives were chemically synthesized. Their biological activities were determined as MIC and IC/sub 50/ unit against various pathogenic microorganisms in vitro. 5'-amino-5'-deoxyuridine-cyclo(Phe-Asp)(23), 5-iodo-5'-amino-deoxyuridine-penicillin G(26) were the most efficient; their IC/sub 50/ against L5178Y murine lymphoma cell was 6.5 h/ml, MIC against S. aureus (+) and E. coli (-) was 6.25 g/ml. MIC of 5-bromo-2', 3'-O-isopropylideneuridine(6) against Trichophyton rubrum was 0.2 g/ml. And 5'-monophosphate derivatives are more active than simple uridine derivatives, suggesting other modified nucleoside 5'-phosphate may be worthwhile examing further as a new prodrugs.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.993-997
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• 2008

Two directional ring-closing metathesis (RCM) was applied successfully to the synthesis of 4'-vinylated carbocyclic nucleoside analogues from the trivinyl intermediate 12, which was readily made using a sequential Claisen rearrangement and ring-closing metathesis (RCM) starting from Weinreb amide 5. An antiviral evaluation of the synthesized compounds against various viruses such as HIV, HSV-1, HSV-2 and HCMV revealed that the guanine analogue 20 have moderate anti-HIV activity in the MT-4 cell line ($EC_{50}$ = 10.2 $\mu$ M).

• Journal of Microbiology
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• v.35 no.1
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• pp.15-20
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• 1997

Kinetic studies were done to elucidate the reaction mechanism of purine nucleoside phosphorylase (PNP) in Micrococcus Luteus. PNP catalyzes the reversible phosphorolysis of ribonucleosides to their respective base. The effect of alternative competing substrates suggested that a single enzyme was involved in binding to the active site for all purine nucleosides, inosine, deoxyiosine, guanosine, deoxyguanosine, adenosine and deoxyadenosine. Affinity studies showed that pentose moiety reduced the binding capacity and methylation of ring N-1 of inosine and guanosine had little effect on binding to bacterial enzyme, whereas these compounds did not bind to the mammalian enzymes. The initial velocity and product inhibition studies demonstrated that the predominant mechanism of reaction was an ordered bi, bi reaction. The nucleoside bound to the enzyme first, followed by phosphate. Ribose 1-phosphate was the first product to leave, followed by base.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.2989-2992
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• 2009

An efficient synthetic route of novel 2′(${\alpha}$)-C-fluoro-2′(${\beta}$)-C-methyl carbocyclic nucleoside analogues is described. The key fluorinated intermediate 7 was prepared from the epoxide intermediate 5 via selective ring-opening of epoxide. Coupling of 7 with nucleosidic bases under the Mitsunobu reactions followed by deprotection afforded the target carbocyclic nucleoside analogues. The synthesized compounds were evaluated as inhibitors of the hepatitis C virus (HCV) in Huh-7 cell line in vitro.