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1.
Smriti Srivastava Sunil K. Singh Vivek K. Sharma Priyanka Mangla Carl E. Olsen 《Nucleosides, nucleotides & nucleic acids》2015,34(6):388-399
Three triazole-linked nonionic xylo-nucleoside dimers TL-t-TxL, TL-t-ABzxL and TL-t-CBzxL have been synthesized for the first time by Cu(I) catalyzed azide-alkyne [3 + 2] cycloaddition reaction (CuAAC) of 1-(3′-azido-3′-deoxy-2′-O,4′-C-methylene-β-D-ribo-furanosyl)thymine with different alkynes, i.e., 1-(5′-deoxy-5′-C-ethynyl-2′-O,4′-C-methylene-β-D-xylofuranosyl)thymine, 9-(5′-deoxy-5′-C-ethynyl-2′-O,4′-C-methylene-β-D-xylo-furanosyl)-N6-benzoyladenine and 1-(5′-deoxy-5′-C-ethynyl-2′-O,4′-C-methylene-β-D-xylofuranosyl)-N4-benzoylcytosine in 90%–92% yields. Among the two Cu(I) reagents, CuSO4.5H2O-sodium ascorbate in THF:tBuOH:H2O (1:1:1) and CuBr.SMe2 in THF used for cycloaddition (click) reaction, the former one was found to be better yielding than the latter one. 相似文献
2.
H. A. Tajmir-Riahi 《Journal of biomolecular structure & dynamics》2013,31(6):1169-1186
Abstract The interaction of adenosine-5′-monophosphate (5′-AMP), guanosine-5′-monophosphate (5′-GMP) and 2′-deoxyguanosine-5′-monophosphate (5′-dGMP) with the [Co(NH3)6]3+, [CO(NH3)5C1]2+ and [CO(NH3)4C12]+ cations has been investigated in aqueous solution with metal/nucleotide ratios (r) of 1/2, 1 and 2 at neutral pH. The solid complexes have been isolated and characterized by FT-IR and 1H-NMR spectroscopy. The complexes are polymeric in nature both in the crystalline solid and aqueous solution. The binding of the cobalt-hexammine cation is indirectly (via NH3) through the N-7 and the PO3 2- groups of the AMP and via O-6, N-7 and the PO3 2- of the GMP and dGMP anions (outer-sphere). The cobalt-pentammine and cobalt-tetrammine bindings are through the phosphate groups (inner-sphere) and the N-7 site (outer-sphere) of these nucleotide anions. The ribose moiety shows C2′-endo/anti conformation, in the free AMP and GMP anions as well as in the cobalt-ammine - AMP complexes, whereas a mixture of the C2′-endo/anti and C3′-endo/anti sugar puckers were observed for the Co(NH3)6-GMP, Co(NH3)5-GMP and a C3′-endo/anti conformer for the Co(NH3)4-GMP complexes. The deoxyribose showed an O4′-endo/anti conformation for the free dGMP anion and a C3′-endo/anti for the Co(NH3)6-dGMP, Co(NH3)5-dGMP and Co(NH3)4-dGMP complexes. 相似文献
3.
A series of 2′-fluorinated adenosine compounds, dAfl, dAflp, pdAfl, dAfl-A, A-dAfl, and dAfl-dAfl, have been investigated by nmr spectroscopies. The 1H-, 19F-, and 31P-nmr data provide structural information from different parts of these moleucles. The pKa of the phosphate group of these two 2′-fluoro-2′-deoxyadenosine monophosphates was found to be the same as that of hte parent adenosine monophosphate. As for the pentose conformation, the 3E population is greatly increased as a result of the fluorine substitution at the C2′ position. However, the populations of conformers of gg (C4′-C5′) and g′g′ (C5′-O5′) and the average angle ?′(C3′-O3′) of the 2′-fluoro compounds remain unchanged as compared to the natural riboadenosine monomer and dimer (A-A). Thefefore, the backbone conformation of the 2′-fluoro-2′-deoxy-adenosine, its monophosphates and dimers, resembles that of RNA. The extent of base-base overlapping in these 2′-fluoro-2′-deoxy-adenosine-containing dimers is also found to be similar to or even greater than A-A. Thus, the conformations of these compounds can be considered as those in the RNA family. These fluorocompounds also serve as models for a careful study on the 19F-nmr in nucleic acid. The 19F chemical-shift values are sensitive to the environment of the fluorine atom such as ionic structure of the neighboring group(s) (phosphate of base), solvation, and ring-ruccent anisotropic effect from the base(s). Qualitatively, the change of the 19F chemical-shift values (up to 2 ppm) is much larger than that of 1H-nmr (up to 0.5 ppm) in the dimers. Using dAfl·poly(U), poly(dAfl)·poly(dAfl), and poly(dAfl)·poly(U) helix–coil transition as model systems, the linewidth of 19F in dAfl- residues reflects effectively the mobility of the unit in the nucleic acid complex as calibrated by uv data and by 1H-nmr. Therefore, application of 19F-nmr spectroscopy on fluorine-substituted nucleic acid can also be used to detect nucleic acid-nucleic acid interaction in complicated systems. 相似文献
4.
Byung-Chang Suh Jin H. Son Tong H. Joh Kyong-Tai Kim 《Journal of neurochemistry》1997,68(4):1622-1632
Abstract: We found that extracellular ATP can increase the intracellular Ca2+ concentration ([Ca2+]i) in mouse pineal gland tumor (PGT-β) cells. Studies of the [Ca2+]i rise using nucleotides and ATP analogues established the following potency order: ATP, adenosine 5′-O-(3-thiotriphosphate) ≥ UTP > 2-chloro-ATP > 3′-O-(4-benzoyl)benzoyl ATP, GTP ≥ 2-methylthio ATP, adenosine 5′-O-(2-thiodiphosphate) (ADPβS) > CTP. AMP, adenosine, α,β-methyleneadenosine 5′-triphosphate, β,γ-methyleneadenosine 5′-triphosphate, and UMP had little or no effect on the [Ca2+]i rise. Raising the extracellular Mg2+ concentration to 10 mM decreases the ATP-and UTP-induced [Ca2+]i rise, because the responses depend on the ATP4? and UTP4? concentrations, respectively. The P2U purinoceptor-selective agonist UTP and the P2Y purinoceptor-selective agonist ADPβS induce inositol 1,4,5-trisphosphate generation in a concentration-dependent manner with maximal effective concentrations of ~100 µM. In sequential stimulation, UTP and ADPβS do not interfere with each other in raising the [Ca2+]i. Costimulation with UTP and ADPβS results in additive inositol 1,4,5-trisphosphate generation to a similar extent as is achieved with ATP alone. Pretreatment with pertussis toxin inhibits the action of UTP and ATP by maximally 45–55%, whereas it has no effect on the ADPβS response. Treatment with 1 µM phorbol 12-myristate 13-acetate inhibits the ADPβS-induced [Ca2+]i rise more effectively than the ATP- and UTP-induced responses. These results suggest that P2U and P2Y purinoceptors coexist on PGT-β cells and that both receptors are linked to phospholipase C. 相似文献
5.
E. K. Nénonéné F. Radja M. Carli L. Grondin T. A. Reader 《Journal of neurochemistry》1994,62(5):1822-1834
Abstract: The selective serotonin (5-HT) agonist 8-hydroxydipropylaminotetralin (8-OH-DPAT) has been extensively used to characterize the physiological, biochemical, and behavioral features of the 5-HT1A receptor. A further characterization of this receptor subtype was conducted with membrane preparations from rat cerebral cortex and hippocampus. The saturation binding isotherms of [3H]8- OH-DPAT (free ligand from 200 pM to 160 nM) revealed high-affinity 5-HT1A receptors (KH= 0.7–0.8 nM) and lowaffinity (KL= 22–36 nM) binding sites. The kinetics of [3H]8-OH-DPAT binding were examined at two ligand concentrations, i.e., 1 and 10 nM, and in each case revealed two dissociation rate constants supporting the existence of high- and low-affinity binding sites. When the high-affinity sites were labeled with a 1 nM concentration of [3H]8- OH-DPAT, the competition curves of agonist and antagonist drugs were best fit to a two-site model, indicating the presence of two different 5-HT1A binding sites or, alternatively, two affinity states, tentatively designated as 5-HT1AHIGH and 5-HT1ALOW. However, the low correlation between the affinities of various drugs for these sites indicates the existence of different and independent binding sites. To determine whether 5-HT1A sites are modulated by 5′-guanylylimidodiphosphate, inhibition experiments with 5-HT were performed in the presence or in the absence of 100 μM 5′-guanylylimidodiphosphate. The binding of 1 nM [3H]8-OH-DPAT to the 5-HT1AHIGH site was dramatically (80%) reduced by 5′-guanylylimidodiphosphate; in contrast, the low-affinity site, or 5-HT1ALOW, was seemingly insensitive to the guanine nucleotide. The findings suggest that the high-affinity 5-HT1AHIGH site corresponds to the classic 5-HT1A receptor, whereas the novel 5-HT1ALOW binding site, labeled by 1 nM [3H]8-OH-DPAT and having a micromolar affinity for 5-HT, may not belong to the G protein family of receptors. To further investigate the relationship of 5-HT1A sites and the 5-HT innervation, rats were treated with p-chlorophenylalanine or with the neurotoxin p-chloroamphetamine. The inhibition of 5-HT synthesis by p-chlorophenylalanine did not alter either of the two 5-HT1A sites, but deafferentation by p-chloroamphetamine caused a loss of the low-affinity [3H]8-OH- DPAT binding sites, indicating-that these novel binding sites may be located presynaptically on 5-HT fibers and/or nerve terminals. 相似文献
6.
A comparative study has been made of the configurational effects on the conformational properties of α- and β-anomers of purine and pyrimidine nucleoside 3′,5′,-cyclic monophosphates and their 2′-arabino epimers. Correlation between orientation of the base and the 2′-hydroxyl group have been studied theoretically using the PCILO (Perturbative Configuration Interaction using Localized Orbitals) method. The effect of change in ribose puckering on the base-hydroxyl interaction has also been studied. The result show that steric repulsions and stabilizing effects of intramolecular hydrogen bonding between the base and the 2′-hydroxyl (OH) group are of major importance in determining configurations of α-anomers and 2′-arabino-β-epimers. For example, hydrogen bonding between the 2′-hydroxyl group and polar centers on the base ring is clearly implicated as a determinant of syn-anti preferences of the purine (adenine) or pyrimidine (uracil) bases in α-nucleoside 3′,5′-cyclic monophosphates. Moreover, barrier heights for interconversion between conformers are sensitive to ribose pucker and 2′-OH orientations. The result clearly show that a change in ribose-ring pucker plays an essential role in relieving repulsive interaction between the base and the 2′-hydroxyl group. Thus a C2′-exo-C3′-endo (2T3) pucker is favored for α-anomers in contrast with the C4′-exo-C3′-endo (4T3) from found in β-compounds. 相似文献
7.
1H- and 31P-nmr spectroscopy have been used to investigate the self-association of M2(5′-CMP) [M = Li+, Na+, K+, Rb+, or (CH3)4 N+; 5′-CMP = cytidine 5′-monophosphate], the self-association of Li2(5′-GMP) (5′-GMP = guanosine 5′-monophosphate), and the heteroassociation of 5′-GMP and 5′-CMP (1 : 1 mole ratio) in aqueous solution as a function of the nature of the monovalent cation. Proton spectral differences for the different 5′-CMP salts exhibit a cation-size dependence and have been ascribed to a change in the stacking geometry. An average stacking association constant of 0.63 ± 0.24M?1 at 1°C, consistent with the weak stacking interactions of the cytosine bases, was determined for the 5′-CMP salts. Heteroassociation of 5′-GMP and 5′-CMP follows the reverse of the cation order for the formation of ordered aggregates of 5′-GMP. Heteroassociation occurs in the presence of Li+, Na+, and Rb+ ions, but only self-association occurs for the K+ nucleotides. Li2(5′-GMP), which does not form ordered species, self-associates to form disordered base stacks with a stacking constant of 1.63 ± 0.11M?1 at 1°C. 相似文献
8.
The predominant complex formed by the reaction of cis-(NH3)2PtCl2 and guanylyl(3′-5′)cytidine has been isolated. The molar ratio of the binding of cis-(NH3)2PtCl2 to guanylyl(3′-5′)-cytidine is 1:2. The values of proton dissociation constant due to guanine and cytosine bases provide useful information for determining the binding site of the isolated complex. In addition, nmr and ir spectral data were used to determine the binding site. cis-(NH3)2PtCl2 coordinates to guanylyl(3′-5′)cytidine through N(7) position of the guanine base, but cytosine base does not participate in the binding to cis-(NH3)2Pt2+. Interbase crosslink has not been detected. The binding specificity of cis-(NH3)2PtCl2 to guanine base is discussed. 相似文献
9.
R. K. Singh S. Ohuchi T. Wada T. Hata# 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):123-130
Abstract 5′-Chloro-5′-deoxy-N,3′-O-dibenzoylthymidine (3a), 5′-chloro-5′-deoxy-N4, 3′-O-dibenzoyldeoxycytidine(3b), 5′-chloro-5′-deoxy-N6,3′-O-dibenzoyldeoxyadenosine(3c), N-benzoyl-1-(3-chloro-2,3-dideoxy-5-O-trityl-ß-D-xylofuranosyl)thymine (5a) and N6-benzoyl-9-(3-chloro-2,3-dideoxy-5-O-trityl-ß-D-xylofuranosyl)adenine (5b) have been synthesized in very high yields using a new efficient reagent, tris(2,4,6-tribrom-ophenoxy)dichlorophosphorane (BDCP). The reaction time was greatly reduced to 5–8 min. NOE data suggested an inversion of configuration at C3-position and thus an SN2 mechanism has been proposed for the chlorination reaction. 相似文献
10.
Reactions of RuCl2(PR3)3 [PR3 = PPh3 or P(p-tolyl)3 with several monomeric phosphine complexes of rhodium(III), iridium(III) and platinum(IV) have been studied. The reactions with mer-MCl3(P′R3)3 (M = Rh, P′R3 = PEt2Ph, PMe2Ph, PMe2Ph; M = Ir, P′R3 = PBuPh2, PMePh2, PEt2Ph) involves a phosphine ligand transfer between metal atoms to afford novel dark coloured heterobimetallic complexes containing a triple chloro-bridge. The reactions of RuCl2(PR3)3 with PtCl4(P′R3)2 (P′R3 = PEt2Ph, PBu2Ph), however, do not give evidence for the formation of dinuclear complexes containing the (RuCl3Pt) unit, but a reduction of PtIV to PtII occurs with transfer of phosphine ligands between the two metals. The formulation of these complexes has been established by 31P NMR spectroscopy. 相似文献
11.
《Free radical research》2013,47(12):1431-1437
The carbonate radical anion CO3?? is a potent reactive oxygen species (ROS) produced in vivo through enzymatic one-electron oxidation of bicarbonate or, mostly, via the reaction of CO2 with peroxynitrite. Due to the vitally essential role of the carbon dioxide/bicarbonate buffer system in regulation of physiological pH, CO3?? is arguably one of the most important ROS in biological systems. So far, the studies of reactions of CO3?? with DNA have been focused on the pathways initiated by oxidation of guanines in DNA. In this study, low-molecular products of attack of CO3?? on the sugar–phosphate backbone in vitro were analyzed by reversed phase HPLC. The selectivity of damage in double-stranded DNA (dsDNA) was found to follow the same pattern C4′ > C1′ > C5′ for both CO3?? and the hydroxyl radical, though the relative contribution of the C1′ damage induced by CO3?? is substantially higher. In single-stranded DNA (ssDNA) oxidation at C1′ by CO3?? prevails over all other sugar damages. An approximately 2000-fold preference for 8-oxoguanine (8oxoG) formation over sugar damage found in our study identifies CO3?? primarily as a one-electron oxidant with fairly low reactivity toward the sugar–phosphate backbone. 相似文献
12.
The structure of the cis-[Pt(NH3)2(3′-CMP)2]2? ion, isolated in a partially protonated form as its cesium salt, has been analyzed by single-crystal x-ray diffraction methods. The 3′-CMP ligands bind in a monodentate fashion through their N(3) atoms: in contrast to the structure of [Pt(en)(5′-CMP)]2, no covalent platinum-phosphate bonding is found. This compound represents the first example of a 1:2 cis-metal/cytosine complex structurally characterized. 相似文献
13.
《Inorganica chimica acta》1988,145(2):191-194
Monthioformate and dithioformate complexes of [HRu(η5-C5H5)(EPh3)(E′Ph3)] (E, E′ P, As, Sb) have been synthesized as a result of the insertion reactions of [HRu(η5-C5H5)(EPh3)(E′Ph3)] with carbonyl sulfide and carbon disulfide. The complexes were characterized by microanalytical, infra red, 1H NMR, 13C NMR spectral data, molecular weight determination along with other studies. 相似文献
14.
Jeffrey K. Glenn Meredith A. Morgan Mary B. Mayfield Masaaki Kuwahara Michael H. Gold 《Biochemical and biophysical research communications》1983,114(3):1077-1083
An H2O2-requiring enzyme system was found in the extracellular medium of ligninolytic cultures of Phanerochaete chrysosporium. The enzyme system generated ethylene from 2-keto-4-thiomethyl butyric acid (KTBA), and oxidized a variety of lignin model compounds including the diarylpropane 1-(4′-ethoxy-3′-methoxyphenyl) 1,3-dihydroxy-2-(4″-methoxyphenyl)propane (I), a β-ether dimer 1-(4′-ethoxy-3′-methoxyphenyl)glycerol-β-guaiacyl ether (IV) and an olefin 1-(4′-ethoxy-3′-methoxy-phenyl)1,2-propene (VI). The products found were equivalent to the metabolic products previously isolated from intact ligninolytic cultures. In addition, the enzyme system partially degraded 14C-ring labeled lignin. The enzyme was not found in high nitrogen (N) cultures, nor in cultures of a ligninolytic mutant strain which is incapable of metabolizing lignin. 相似文献
15.
P.J. Cayley J. Feeney B.J. Kimber 《International journal of biological macromolecules》1980,2(4):251-255
We have measured the 31P n.m.r. spectra of NADP+ and NADPH in their binary complexes with Escherichia coli dihydrofolate reductase and in ternary complexes with the enzyme and folate or methotrexate. The 31P chemical shift of the 2′ phosphate group is the same in all complexes; its value indicates that it is binding in the dianionic state and its pH independence suggests that it is interacting strongly with cationic residue(s) on the enzyme. Similar behaviour has been noted previously for the complexes with the Lactobacillus casei enzyme although the 31P shift is somewhat different in this complex, possibly due to an interaction between the 2′ phosphate group and His 64 which is not conserved in the E. coli enzyme. For the coenzyme complexes with both enzymes 31POC21H2′ spin-spin interactions were detected (7.5–7.8 Hz) on the 2′ phosphate resonances, indicating a POC2H2′ dihedral angle of 30 or 330 : this is in good agreement with the value of 330° measured in crystallographic studies1 (Matthews et al., 1978) on the L. casei enzyme. NADPH-MTX complex. The pyrophosphate resonances are shifted to different extents in the various complexes and there is evidence that there is more OPO bond angle distortion in the E. coli enzyme complexes than in those with the L. casei enzyme. The effects of 31POC51H5′ spin coupling were detected on one pyrophosphate resonance and indicate that the POC5H5′ torsion angle has changed by at least ~30° on binding to the E. coli enzyme: this is considerably less than the distortion (~50°) observed previously in the L. casei enzyme complex. 相似文献
16.
G.A. Barber 《Archives of biochemistry and biophysics》1975,167(2):718-722
Extracts of the green alga Chlorella pyrenoidosa have been shown to catalyze the epimerization of guanosine 5′-diphosphate-d-mannose to guanosine 5′-diphosphate-l-galactose. The equilibrium is about 0.1 in the direction of the l-galactosyl nucleotide and is independent of temperature. The Km for guanosine 5′-diphosphate-d-mannose was determined to be about 1.2 × 10?4m. Guanosine 5′-diphosphate-l-fucose (6-deoxy-l-galactose) also serves as a substrate for the enzyme, and the product of that reaction appears to be guanosine 5′-diphosphate-d-rhamnose (6-deoxy-d-mannose). 相似文献
17.
Crosslinking of chemically reactive A-U-G analogs to ribosomal proteins within initiation complexes.
O. Pongs H.U. Petersen M. Grunberg-Manago E. Lanka R. Bald G. Stöffler 《Journal of molecular biology》1979,134(2):329-345
A-U-G analogs, either reactive on their 5′ or their 3′ side, were employed in affinity labeling of the ribosomal A-U-G binding site. These experiments have been carried out such that the chemically reactive A-U-G analog became covalently bonded to ribosomal proteins only in the presence of fMet-tRNAfMet and initiation factors. Subsequent radioimmunodiffusion of A-U-G-labeled proteins identified proteins IF3, S1, S18, S21 and L11 as being in the neighborhood of the ribosomal codon binding site. A location of reactive sites of these proteins relative to the P or A site bound codon is, however, not clear.The A-U-G labeling results are quantitatively as well as qualitatively very different in the absence or presence of fMet-tRNAfMet. It is concluded, therefore, that fMet-tRNAfMet directs A-U-G into its final binding site. Streptomycin cannot release fMet-tRNAfMet from initiation complexes which contain irreversibly bound 5′- {4-(bromoacetamido)phenylphospho}-adenylyl-(3′–5′)-uridylyl-(3′–5′)-guanosine. This suggests that codon-anticodon interaction between A-U-G and fMet-tRNAfMet is still intact in the P site of the ribosome. 相似文献
18.
Anu Arya Divya Mathur Abhilash Tyagi Rajesh Kumar Vinod Kumar Carl E. Olsen 《Nucleosides, nucleotides & nucleic acids》2013,32(12):646-659
An efficient protocol has been developed for the synthesis of a small library of 3′-deoxy-3′-(4-substituted-triazol-1-yl)-5-methyluridine using Cu(I)-catalyzed Huisgen–Sharpless–Meldal 1,3-dipolar cycloaddition reaction of 3′-azido-3′-deoxy-5-methyluridine with different alkynes under optimized condition in an overall yields of 76%–92%. Here, the azido precursor compound, i.e., 3′-azido-3′-deoxy-5-methyluridine was chemoenzymatically synthesized from D-xylose in good yield. Some of the alkynes used in cycloaddition reaction were synthesized by the reaction of hydroxycoumarins or naphthols with propargyl bromide in acetone using K2CO3in excellent yields. All synthesized compounds were unambiguously identified on the basis of their spectral (IR, 1H-, 13C NMR spectra, and high-resolution mass spectra) data analysis. 相似文献
19.
Robert J. Suhadolnik Paul W. Doetsch Yair Devash Earl E. Henderson Ramamurthy Charubala Wolfgang Pfleiderer 《Nucleosides, nucleotides & nucleic acids》2013,32(4):351-366
Abstract The effect of the 2′,5′-adenylate and cordycepin trimer cores on DNA and protein synthesis in human umbilical cord lymphocytes, lymphoblasts, peripheral blood lymphocytes and Epstein-Barr virus infected lymphocytes and their metabolism in tissue culture medium have been studied. [32P]Adenylate and [32P]- and [3H]cordycepin trimer cores were synthesized either enzymatically or chemically and added to cells in culture. The half-lives of the 2′,5′-A3 core and 2′,5′-3′dA3 core in tissue culture were 3 and 17 hr, respectively. Chromatographic analysis of the TCA-soluble extracts of the lymphocytes and lymphoblasts treated with 2′,5′-[3H]A3 showed that 0.25% of the 32P was identified as AMP, ADP, ATP and inorganic phosphate. By the more sensitive 2′,5′-p3A4[32P]pCp radiobinding assay, 2′,5′-A3 was detected in the TCA supernatants; however, there was no 5′-rephosphorylation. With the [3H]- and [32P]cordycepin trimer core, 0.55% and 1.3% of the radioactivity was in the TCA soluble extracts. Although there was no 5′-rephosphorylation as determined by radiobinding assay, the intact cordycepin trimer core was detected by tlc, radiobinding assay, and HPLC. Furthermore, in two experiments, the concentration of the cordycepin trimer core bound to or taken up by the lymphocytes was three-fold greater than the concentration in the medium. 2′,5′-A3 and 2′,5′-3′dA3 cores were both antimitogenic, but did not inhibit protein synthesis. 相似文献