共查询到20条相似文献,搜索用时 15 毫秒
1.
《Nucleosides, nucleotides & nucleic acids》2013,32(5-8):755-758
Abstract A method for the selective introduction of the N2-(dimethylamino)methylene group into 8-thio-9-(2-hydroxyethoxymethyl)guanine (1) has been developed. The effect of the N2-amidine protection on the S-alkylation of 1 was studied. 相似文献
2.
Abstract D-Mannitol nucleosides with a purine base moiety have been conveniently synthesized strating from 1,5-anhydro-4,6-O-benzylidene-D-glucitol. The 3-OH function of 1,5-anhydro-4,6-O-benzylidene-D-glucitol was selectively protected with t-butyldimethylsilyl group and subsequently converted to the corresponding 0-triflate derivative for the introduction of the nucleobase moietes. These nucleoside derivatives were transformed to 1,5-Anhydro-6-O-MMTr-2-(N6-benzoyladenin-9-yl)-2-deoxy-3-O-TBDMS-D-mannitol and 1,5-Anhydro-6-O-MMTr-2-(N2-isobutyryl-guanin-9-yl)-2-deoxy-3-O-TBDMS-D-mannitol, useful as the building blocks for oligonucleotide synthesis. Also, the synthesis of the corresponding fully deprotected anhydrohexitol nucleosides were achieved for evaluation of antiviral activity test. 相似文献
3.
The structures and stabilities of eleven N13
+ and N13
– isomers have been investigated with second-order Møller–Plesset (MP2) and density functional theory (DFT) methods. Five N13
+ isomers and six N13
– isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13
+ cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains. It is different from those of the N7
+ and N9
+ clusters, but similar to the N11
+ cluster. Meanwhile, the most stable N13
– structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N7
– and N9
– clusters, but also from the N11
– cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species.
Figure Optimized geometrical parameters of N13
+ isomer C-2
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4.
Abstract The synthesis of phosphoramidites (2 and 3) derived from hypoxanthine and isoguanine N7-21-deoxyribonucleosides is described. Solid-phase synthesis furnishes oligonucleotides containing N7-glycosylated purines. New base pairs between purine N7- and N9-nucleosides are proposed. 相似文献
5.
Abstract Several O6-aryl-2′-deoxyinosines were synthesized and found to undergo conversion to N6-substituted-2′-deoxyadenosines upon treatment with aqueous amines. The kinetics for reaction of these nucleosides with various amines suggests that O6-phenyl- and O6-(p-nitrophenyl)-2′-deoxyinosine are suitable “convertible nucleoside” precursors for the site-specific introduction of functionally tethered 2′-deoxyadenosines into DNA. 相似文献
6.
It was suggested that the abnormally high N 2 O values found in 130,000–160,000 year-old Vostok ice core samples, characterized by high δ 15 N and low δ 18 O values, resulted from in situ microbial N 2 O production. To substantiate these observations we obtained new geochemical data from the last glacial period and showed the existence of additional small N 2 O anomalies. To test the hypothesis that microbial metabolism could contribute to these anomalies, we developed protocols for examining the ability of Nitrosomonas cryotolerans cells to produce N 2 O at subfreezing temperatures. Our results show that these model, frozen cultures produce N 2 O at temperatures as low as ?32°C. 相似文献
7.
Pravin L. Kotian V. Satish Kumar Tsu-Hsing Lin Yahya El-Kattan Ajit Ghosh Minwan Wu 《Nucleosides, nucleotides & nucleic acids》2013,32(2):121-140
The introduction of versatile functional groups, allyl and ester, at the C-1 position of the acyclic chain in acyclic adenine nucleosides was achieved for the first time directly by alkylation of adenine and N6-protected adenine. Thus, the C-1′-substituted N9-adenine acyclic nucleoside, adenine-9-yl-pent-4-enoic acid ethyl ester (11), was prepared by direct alkylation of adenine with 2-bromopent-4-enoic acid ethyl ester (6), while the corresponding N7-regioisomer, 2-[6, (dimethylaminomethyleneamino)-purin-7-yl]-pent-4-enoic acid ethyl ester (10), was obtained in one step by the coupling of N,N-dimethyl-N′- (9H-purin-6-yl)-formamidine (9) with 2-bromopent-4-enoic acid ethyl ester (6). The functional groups, ester and allyl, were converted to the desired hydroxymethyl and hydroxyethyl groups, and subsequently to phosphonomethyl derivatives and corresponding pyrophosphorylphosphonates. 相似文献
8.
Wajdi Michel Zoghaib Shajan Mannala V. Sagar Gupta Guy Tourigny 《Nucleosides, nucleotides & nucleic acids》2013,32(4):364-376
Analogs of (E)-5-(2-bromovinyl)-2 ′-deoxycytidine (BrVdCyd) (1) by substitution at N4 were synthesized to impart resistance against deamination. The anti-HSV-1 activity and solution conformation of these analogs were determined. N4-Acetyl-BrVdCyd (2) was a potent inhibitor of HSV-1 replication whereas N4-propanoyl-BrVdCyd (3) had good activity and N4-Butanoyl-BrVdCyd (4) had only low activity against HSV-1 replication. N4-Methyl-BrVdCyd (5) was devoid of activity against HSV-1. 相似文献
9.
Akihiro Imaeda Fumiaki Tomoike Mayu Hayakawa Kosuke Nakamoto Yasuaki Kimura Naoko Abe 《Nucleosides, nucleotides & nucleic acids》2013,32(12):972-979
AbstractsiRNA is a powerful method to suppress specific gene expression and has recently been utilized for molecular biology as well as medicine. However, introduction of dsRNA stimulates immune-responses as side-effects. In the present study, we utilized N6-methyl adenosine, one of the natural modified nucleosides, instead of adenosine in siRNA. When adenosine in the passenger or guide strand of siRNA was completely replaced with N6-methyl adenosine, the immune response against siRNA was evaded without any reduction in RNAi activity. This knowledge will promote the medical application of siRNA and enhance our understanding on cellular discrimination of non-self and self dsRNA. 相似文献
10.
Abstract Phosphorylation of 1-(2-deoxy-β-D-xylofuranosyl)thymine (1) or 9-(2-deoxy-β-D-xylofuranosyl)adenine (3) with phosphoryl chloride gives the cyclic 3′,5′-phosphates (2 and 4a) but not the 5′-monophosphates 8a or 8b. The latter are obtained by phosphorylation of the 3′-0-benzoylated 2′-deoxy-β-D-xylonucleosides (7a, b) and subsequent base-catalyzed removal of the benzoyl groups. Compound 3, as the parent dA, depurinates in acidic medium, a reaction which is facilitated in the case of the N6-benzoyl derivative 9b and reduced after the introduction of an amidine protecting group. N-Glycosylic bond hydrolysis of 2′-deoxy-β-D-xylofuranosyl nucleosides is enhanced by a factor of two compared to 2′-deoxy-β-D-ribofuranosyl nucleosides. 相似文献
11.
Abstract Analyses of the pH dependence of 13C chemical shifts and 13C-1H coupling constants of formycin in aqueous soluion revealed two pKa′s, at 4.4 and 9.7, corresponding to a protonation at N4 and an ionization at N1. The N4-protonation results in the transfer of a pyrazolo ring hydrogen from N2 to N2-At physiological pH, formycin was found to exist as a mixture of N1H and N2H tautomers, with the former being predominant (>94%). 相似文献
12.
H. Topp H. Groß G. Heller-Schöch G. Schöch 《Nucleosides, nucleotides & nucleic acids》2013,32(6):585-596
Abstract Seven modified ribonucleosides from degraded tRNA and rRNA were quantified in milk from mothers with preterm infants. The amounts of N6-threoninocarbonyladenosine, N2, N2-dimethylguanosine and pseudouridine supplied in the milk have been estimated and related to the respective urinary amounts excreted by preterm infants. 相似文献
13.
Yoshimitsu Yamazaki Hideo Suzuki Akira Kamibayashi Naoharu Watanabe Nobutaka Takahashi 《Bioscience, biotechnology, and biochemistry》2013,77(9):1945-1950
Five new derivatives of adenosine, N6-[(1-methylethyl)thiomethyl]-(1), N6-methyithiomethyl-(2), N6-phenylthiomethyl-(3), N6-[(3-amino-3-carboxypropyl)thiomethyl]-(4), and N6-[(2-amino-2-carboxyethyl)thiomethyl]adenosine (5), were synthesized and their cytokinin activity was tested in the Amaranthus betacyanin assay and the soybean callus growth.1, 2, and 3 were active in the former assay and all five compounds were active in the latter assay. The activities of the compounds were, however, weaker than those of the reference derivatives, in which Sulfides were replaced by methylenes, N6-isopentyl-, N6-n-propyl-, N6-benzyl-, and N6-(5-amino-5-carboxypentyl)adenosine. This fact indicates that the sulfide structure introduced into the N6-side chains had the effect of reducing cytokinin activity. 相似文献
14.
《Nucleosides, nucleotides & nucleic acids》2013,32(4-7):1279-1282
The 9-deazaguanine N7-2′-deoxyribofuranoside (3) as well as the bromo and iodo derivatives 4a,b were synthesized and incorporated in oligonculeotide duplexes and triplexes. Their base pairing properties were investigated and compared with those of the parent purine N7-2′-deoxyribofuanosides. 相似文献
15.
Stephen Freese Jörg Hoheisel Hans Lehrach George Wright 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1507-1524
Abstract Several N2-alkyl and N2-phenyl 2′-deoxyguanosine 5′-triphosphates and 2-bromo-2′-deoxyinosine 5′-triphosphate were synthesized and tested as substrates for E. coli DNA polymerase I with a template: primer system requiring incorporation of 85 nucleotides. N2-Methyl-dGTP and N2-ethyl-dGTP were found to be efficiently incorporated in place of dGTP to give full length product. N2-n-Hexyl-dGTP supported limited full length synthesis at high concentration, but N2-phenyl- and N2-(p-n-butylphenyl)-dGTP were poor substrates. 2-Bromo-2′-deoxyinosine 5′-triphosphate was a good substrate for pol I, and it was a replacement only for dGTP. Melting temperatures of oligodeoxyribonucleotides containing N2-alkyl-dG residues, annealed to complementary single stranded DNA, were lower than that of the normal oligomer. 相似文献
16.
《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):227-237
The regioselective synthesis of 4‐nitroindazole N 1‐ and N 2‐(β‐d‐ribonucleosides) (8, 9, 1b and 2b) is described. The N 1‐regioisomers are formed under thermodynamic control of the glycosylation reaction [fusion reaction or Silyl Hilbert‐Johnson glycosylation for 48 h (66%)], while the kinetic control (Silyl Hilbert‐Johnson glycosylation for 5 h) afforded only the N 2‐isomer (64%). The structures of the nucleosides 1b and 2b were assigned by single crystal X‐ray analyses. The 4‐amino‐N 1‐(β‐d‐ribofuranosyl)‐1H‐indazole (3b) was obtained from the nitro nucleoside 1b by catalytic hydrogenation. Compound 3b shows fluorescence while the 4‐nitroindazole nucleosides 1b and 2b do not possess this property. 相似文献
17.
Teruaki Mukaiyama Masashi Nagai Takafumi Matsutani Naoyuki Shimomura 《Nucleosides, nucleotides & nucleic acids》2013,32(1-3):17-30
Abstract Several β-d-ribonucleosides were synthesized in high yields under mild conditions by N-glycosylations of methyl 2,3,5-tri-O-benzoyl-β-d-ribofuranosyl carbonate (1) with trimethylsilylated nucleoside bases in acetonitrile using a catalytic amount of metal iodide such as SnI2, SbI3 or TeI4. A deprotection of N6 -benzoyl group of coupling product took place to a considerable extent when N6 -benzoyl-N6 , N9 -bis(trimethylsilyl)adenine was employed as a nucleoside base using SnI2 or SnCI2 as a catalyst while it was minimized when SbI3 or TeI4 was used. Further, the N-glycosylation of 1 with 7-trimethylsilyltheophylline in the presence of a catalytic amount of metal iodide was more effectively achieved in nitrile solvents other than acetonitrile. 相似文献
18.
Summary Patterns of foliar δ15 N can suggest testable hypotheses concerning N use among and within plant species. However, both spatial and time-series sampling is required to establish how the patterns vary within and among species. On a seasonal basis, foliar δl5 Nrankings may change among the species compared. When symbiotic N2-fixers are among the plants sampled, N2-fixation may be temporally disjunct from the near-0%c, expected foliar δ15 N, which is usually attributed to N2-fixation, and the fates of previously fixed N may not be apparent from a net foliar δ15 N of either soil or plants. 相似文献
19.
Interaction of (2′ -5′) and (3′ -5′) Linked 2-Aminoadenylyl-3-aminoadenosines with Polyuridylic Acid
Masako Muraoka Seizo Takahashi Seiichi Uesugi 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1503-1518
Abstract 2′-5′ and 3′-5′ linked 2-aminoadenylyl-2-aminoadenosines [(2′-5′)n2Apn2A (1) and (3′-5′)n2Apn2A (2)] were synthesized by condensation of 5′-O-monomethoxytrityl-N 2 N 6-dibenzoyl-2-aminoadenosine and N 2,N 6,2′,3′-O-tetrabenzoyl-2-aminoadenosine 5′-phosphate using dicyclohexylcarbodiimide (DCC). The conformational properties of these dimers 1 and 2 were examined by UV, NMR and CD spectroscopy. The results reveal that the 2′-5′-isomer 1 takes a stacked conformation, which contains a larger base-base overlap and is more stable against thermal perturbation with respect to the 3′-5′-isomer 2. Interactions of 1 and 2 with polyuridylic acid (Poly (U)) were also examined by Tm, mixing curves, UV and CD spectra. Both the dinucleoside isomers 1 and 2 formed a complex of 1 : 2 stoichiometry with poly(U), which was much more stable than that of the corresponding ApA isomer 相似文献
20.