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61.
Tomasz Ruman Karolina D?ugopolska Katarzyna Rydel Wojciech Rode 《Bioorganic chemistry》2010,38(3):87-91
Preparation and spectroscopic properties of novel boron-containing derivatives of anti-HIV agent stavudine are presented, The new compounds, (5′-O-(4,4,5,5-tetramethyl-1,3,2-dioxaboronate)-2′-3′-didehydro-2′-3′-dideoxythymidine and 5′-O-(dihydroxyboronate)-2′-3′-didehydro-2′-3′-dideoxythymidine), were prepared by direct reaction between stavudine and reagents containing BH moieties - pinacolborane and borane-dimethylsulfide complexes, respectively. The boron coordination equilibrium of those compounds was analyzed by water titration monitored by NMR. Results of the DFT calculations and NMR experiments pointed to structural and electronic similarity of tetrahedral boron complexes to phosphate group. 相似文献
62.
Modified nucleosides of ribosomal RNA are synthesized during ribosome assembly. In bacteria, each modification is made by a specialized enzyme. In vitro studies have shown that some enzymes need the presence of ribosomal proteins while other enzymes can modify only protein-free rRNA. We have analyzed the addition of modified nucleosides to rRNA during ribosome assembly. Accumulation of incompletely assembled ribosomal particles (25S, 35S, and 45S) was induced by chloramphenicol or erythromycin in an exponentially growing Escherichia coli culture. Incompletely assembled ribosomal particles were isolated from drug-treated and free 30S and 50S subunits and mature 70S ribosomes from untreated cells. Nucleosides of 16S and 23S rRNA were prepared and analyzed by reverse-phase, high-performance liquid chromatography (HPLC). Pseudouridines were identified by the chemical modification/primer extension method. Based on the results, the rRNA modifications were divided into three major groups: early, intermediate, and late assembly specific modifications. Seven out of 11 modified nucleosides of 16S rRNA were late assembly specific. In contrast, 16 out of 25 modified nucleosides of 23S rRNA were made during early steps of ribosome assembly. Free subunits of exponentially growing bacteria contain undermodified rRNA, indicating that a specific set of modifications is synthesized during very late steps of ribosome subunit assembly. 相似文献
63.
A K Tyagi H N Jayaram S Anandaraj B Taylor D A Cooney 《Journal of biochemical and biophysical methods》1979,1(4):221-226
A simple and sensitive method has been developed to separate nucleic acid bases, nucleosides, nucleotides and their precursors by automated chromatography using the amino acid analyzer with lithium citrate buffers. The method is sensitive to a concentration of 5 nmol, linear in the range of 5--100 nmol, and resolves almost all the bases, nucleosides, nucleotides and their precursors of physiologic importance. 相似文献
64.
Parallel stranded (ps) duplexes were constructed by incorporating 7-deaza-2′-deoxyisoguanosine (1a) or its 7-halogenated analogs 1b,c in place of 2′-deoxyisoguanosine. UV and Tm analyses prove the high affinity of ethidium bromide (EB) to these modified duplexes. Steady-state fluorescence measurement shows that the fluorescence is quenched when EB is bound to ps duplexes containing compounds 1a–c. The quenching effect depends on the 7-substituent of the nucleobase. 相似文献
65.
66.
Amino acid contributions to protein recognition of naturally modified RNAs are not understood. Circular dichroism spectra and predictive software suggested that peptide tF2 (S1ISPW5GFSGL10 LRWSY15), selected from a phage display library to bind the modified anticodon domain of yeast tRNAPhe (ASL), adopted a beta-sheet structure. Ala residues incorporated at positions Pro4 and Gly6, both predicted to be involved in a turn, did not alter the peptide binding affinity for the ASLPhe, although major changes in the peptide's CD spectra were observed. Substitutions at three positions Pro4, Gly6, and Gly9, the latter not predicted to be in a turn, reduced the peptide's binding affinity to 4% of that of the unsubstituted tF2 and strongly influenced the peptide's secondary structure. The results suggest that peptides with different conformations, but similar affinities, adopt the optimal binding conformation, indicative of a structurally adaptive model of binding in which the modified RNA serves as a scaffold. 相似文献
67.
Qi Chen Chong Liu Terry L. Bowlin Stewart W. Schneller 《Bioorganic & medicinal chemistry letters》2018,28(9):1456-1458
Synthetically combining the C-4′ side-chain structural features of the antiviral candidates 5′-methylaristeromycin and 5′-homoaristeromycin into a diastereomeric pair of C-4′ side-chain dihydroxylated aristeromycins (6 and 7) is reported. Broad antiviral analyses of the both targets found promising effects towards HBV (6, 6.7?μM and 7, 7.74?μM) and HCMV (only 7, 0.72?μM). No other activity was found. Neither of the diastereomers was cytotoxic in the assays performed. 相似文献
68.
Adnan A. Bekhit Ola A. El-Sayed Yunus M. Siddiqui Mohammed N. Al-Ahdal 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):33-38
Synthesis of a novel series of structurally related pyrazoloquinoline nucleosides is described. All the newly synthesized compounds were examined for their in vitro antiviral activity against herpes simplex type-1 as shown by two different bioassays, namely; crystal violet staining or the MTS tetrazolium dye measurement. The acute toxicity (LD50) values of the biologically active compounds were determined. 相似文献
69.
Nora M. Rateb Hany A. El-Deab Ibrahim M. Abdou 《Nucleosides, nucleotides & nucleic acids》2013,32(9):493-509
Two series of novel 3-cyano-2-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyloxo) pyridines and 3-cyano-2-(2,3,5-tri-O-acetyl-β-D-ribofuranosyloxy)-4-trifluromethyl-6-phenyl pyridine were synthesized using efficient microwave methods. The targeted compounds were obtained in high yields by reacting 2-(1H)-pyridone or its salt with activated sugars using SiO2 under solvent-free conditions. Ammonolysis of the resulted acetylated nucleosides produced 3-cyano-2-(β-D-glucopyranosyloxo)-pyridines and 3-cyano-2-(β-D-ribofuranosyloxy)-4-trifluoromethyl-6-phenyl pyridine. These new products were fully characterized using 1D and 2D NMR. These compounds were screened for their antibacterial activities against G+ and G– bacteria and some found to exhibit better antibacterial activities than the control drug. 相似文献
70.
Federico G. De las Heras María-José Camarasa 《Nucleosides, nucleotides & nucleic acids》2013,32(1):45-56
Abstract A series of alkylating derivatives of 5-subs-tituted 1-glycosyl-1,2,4-triazole having cytostatic activity has been prepared. The compounds synthesized include the 5-hydroxymethyl, 5-halomethyl, 5-(1-aziridino) methyl, and 5-bis (2-chloroethyl) aminomethyl derivatives. 相似文献