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排序方式: 共有496条查询结果,搜索用时 22 毫秒
1.
B Rayner M Matsukura F Morvan J S Cohen J L Imbach 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1989,310(3):61-64
Oligonucleotide analogs consisting exclusively of alpha-anomeric deoxynucleoside units bridged with phosphorothioate linkages have been synthesized and tested in vitro as antiviral agents against human immunodeficiency virus (HIV) in human T cells. Two 28-mers, an homopolymer alpha-S-dC28 and an oligomer alpha-S-anti-rev complementary to the initiation site of the regulatory viral gene rev exhibited antiviral activities comparable to those reported for the corresponding beta-anomeric phosphorothioate analogs. In contrast, a nuclease-resistant homopolymer, alpha-dC28 was inactive. Their preliminary results would indicate that the origin of oligonucleotide phosphorothioate anti-HIV activity is not exclusively correlated with their higher nuclease resistance. 相似文献
2.
Alpha-DNA. IV: Alpha-anomeric and beta-anomeric tetrathymidylates covalently linked to intercalating oxazolopyridocarbazole. Synthesis, physicochemical properties and poly (rA) binding 总被引:5,自引:5,他引:0
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C Gautier F Morvan B Rayner T Huynh-Dinh J Igolen J L Imbach C Paoletti J Paoletti 《Nucleic acids research》1987,15(16):6625-6641
A new set of molecules made of an intercalating agent (oxazolopyridocarbazole, OPC) covalently linked through a polymethylene chain of various length to the 3' end of alpha-anomeric or beta-anomeric tetradeoxynucleotides (alpha- or beta-T4) have been synthesized. The beta-thymidylate modified compound (beta-T4C5OPC) is able to interact with the complementary sequence, beta-poly (rA); this interaction is strongly stabilized compared to the parent compound, beta-oligo(dT)4 and is specific for poly (rA). The molecule synthesized from the unnatural alpha-anomer, alpha-T4C5OPC, is also able to interact with poly (rA) leading to the formation of an alpha-beta hybrid stabilized by the energy provided by the OPC moiety. The stoechiometry of the binding reaction shows that an A-T pairing occurs in the alpha-beta heterohybrids. Tm studies reveal that the alpha-beta heterohybrids are more stable than their beta-beta counterparts. 相似文献
3.
alpha-DNA. VI: Comparative study of alpha- and beta-anomeric oligodeoxyribonucleotides in hybridization to mRNA and in cell free translation inhibition. 总被引:18,自引:15,他引:3
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C Gagnor J R Bertrand S Thenet M Lema?tre F Morvan B Rayner C Malvy B Lebleu J L Imbach C Paoletti 《Nucleic acids research》1987,15(24):10419-10436
alpha and beta-anomeric d(G2T12G2) oligodeoxyribonucleotides were compared for their hybridization to rA12: the observed melting temperatures are 27 degrees C for beta-oligodeoxyribonucleotide/RNA hybrid and 53 degrees C for alpha-oligodeoxyribonucleotide/RNA. alpha-oligonucleotides with the four bases, complementary to natural mRNAs, were synthesized for the first time, labeled at their 5'-end with [32P] and used as probes in Northern blot experiments. In spite of these higher affinities for their target RNA's, they were unable to block translation of natural or synthetic mRNA's in rabbit reticulocyte lysate. We have studied the RNase H activity on model rA12:alpha- or beta-d(G2T12G2) hybrids or on mRNA:alpha- or beta-oligonucleotides hybrids. Specific hybridization protects RNA strech when using alpha-oligonucleotides but not beta-oligonucleotides. Thus, our results show the inability of RNase H to degrade RNA in alpha-oligodeoxyribonucleotides:RNA duplexes. 相似文献
4.
Alpha-DNA VIII: thermodynamic parameters of complexes formed between the oligo-alpha-deoxynucleotides: alpha-d(GGAAGG) and alpha-d(CCTTCC) and their complementary oligo-beta-deoxynucleotides: beta-d(CCTTCC) and beta-d(GGAAGG) are different. 总被引:4,自引:4,他引:0
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The temperature dependence of the formation of a complex between an alpha-d(CCTTCC) hexanucleotide and its complementary beta-d(GGAAGG) sequence was studied and compared to the formation of the beta-d(CCTTCC):beta-d(GGAAGG) complex. Such alpha-beta complex is more stable than the regular beta:beta complex. The Tm value for the alpha:beta complex is 28 degrees C (delta G degrees = -7.3 kcal/mole) while Tm = 20, 1 degree C (delta G degrees = -6.3 kcal/mole) for the beta:beta complex. The stoechiometry of the alpha:beta complex corresponds to the formation of a 1:1 duplex. However, when the alpha- strand is made of alpha-purines: alpha-d(GGAAGG), the stability of the alpha:beta complex, alpha-d(GGAAGG):beta-d(CCTTCC) is found to be lower (Tm = 13.8 degrees C) than the stability of the regular beta-beta complex, leading to the conclusion that the nature of the alpha-sequence is important in terms of stability when considering the synthesis of such a sequence for using it as antisense oligonucleotide. 相似文献
5.
6.
Sabine Lhernould Yannis Karamanos Sylvain Bourgerie Gerard Strecker Raymond Julien Henri Morvan 《Glycoconjugate journal》1992,9(4):191-197
We have previously isolated mannoside and xylomannoside oligosaccharides with one or two terminal reducingN-acetylglucosamine residues from the extracellular medium of white campion (Silene alba) suspension culture. We have now demonstrated the presence of peptide-N
4-(N-acetylglucosaminyl)asparagine amidase (PNGase) activity in cell extracts as well in the culture medium that could explain the production of those compounds. An additional xylomannoside, (GlcNAc)Man3(Xyl)GlcNAc(Fuc)GlcNAc, was characterized, and1H- and13C-NMR assignments for the oligosaccharide Man3(Xyl)GlcNAc(Fuc)GlcNAc were obtained using homonuclear and heteronuclear spectroscopy (COSY).Abbreviations Endo
endo--N-acetylglucosaminidase
- Fuc
fucose
- GlcNAc
N-acetylglucosamine
- Man
mannose
- NMR
nuclear magnetic resonance
- PNGase
peptide-N
4-(N-acetylglucosaminyl)asparagine amidase
- Xyl
xylose 相似文献
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10.
The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
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