共查询到20条相似文献,搜索用时 15 毫秒
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Ahlert Schmidt 《Planta》1975,124(3):267-275
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《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1986,888(2):157-162
The histidine derivative diphthamide occurs uniquely in eukaryotic elongation factor 2 (EF-2), and is the specific target for the diphtheria toxin mono(ADP-ribosyl)transferase. The first step in diphthamide biosynthesis may involve the transfer of an aminocarboxypropyl moiety from S-adenosylmethionine to the imidazole ring of histidine in EF-2, to yield 2-(3-carboxy-3-aminopropyl)histidine and 5′-deoxy-5′-methylthioadenosine (MeSAdo). As the possible nucleoside product of the initial reaction in the diphthamide biosynthetic pathway, MeSAdo could be an inhibitor of diphthamide formation. In the present experiments, we have analyzed the effects of MeSAdo on diphthamide synthesis in a MeSAdo phosphorylase-deficient mutant murine lymphoma cell line (R1.1, clone H3). As measured by susceptibility to diphtheria toxin-induced ADP-ribosylation, MeSAdo inhibited the formation of diphthamide in EF-2. The inhibition was not due to a nonspecific effect on protein synthesis. Indeed, exogenous MeSAdo substantially protected the lymphoma cells from the lethal effects of diphtheria toxin. These results suggest that MeSAdo can specifically modulate the biosynthesis of diphthamide in EF-2 in murine malignant lymphoma cells. 相似文献
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A kinetic analysis of the labeling of the methylated components of messenger RNA and heterogeneous nuclear RNA in mouse L cells indicates that the 5′ terminal cap I structures (m7GpppXmpYp) of mRNA are derived from 5′ terminal cap structures of hnRNA. Most of the hnRNA caps are conserved during processing, whereas only a portion of the internal m6A residues in hnRNA are conserved. The cap II structures (m7GpppXmpYmpZp), which constitute the 5′ termini of some mRNAs, arise by a “secondary” methylation that occurs after the mRNAs have entered the cytoplasm. This secondary methylation is apparently restricted to a particular subclass of mRNAs having a high frequency of pyrimidine nucleotides at position Y, a composition at position X which differs from that of the bulk of the cap I-terminated mRNAs, and a relatively slow rate of turnover. 相似文献
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Masayoshi Yamaguchi Reiko Makino Noriaki Shimokawa 《Molecular and cellular biochemistry》1996,165(2):145-150
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Xue-qiang Yin Wei-kuan Li Minmin Yang Stewart W. Schneller 《Bioorganic & medicinal chemistry》2009,17(8):3126-3129
A synthetic route to (1S,2S,3R,5S)-3-(6-amino-9H-purin-9-yl)-5-fluorocyclopentane-1,2-diol (that is, the 4′-fluoro derivative of 4′-deoxy-5′-noraristeromycin, 3) is described via a fluorinated cyclopentanol, which is in contrast to existing schemes where fluorination occurred once the purine ring was present. Compound 3 was assayed versus a number of viruses. A favorable response was observed towards measles (IC50 of 1.2 μg/mL in the neutral red assay and 14 μg/mL by the visual assay) but this was accompanied by cytotoxicity in the CV-1 host cells (21–36 μg/mL). Among the viruses unaffected by 3 were human cytomegalovirus and the poxviruses (vaccinia and cowpox), which are three viruses that were inhibited by the 4′,4′-difluoro analog of 3 (that is, 2). 相似文献
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利用抗病基因保守序列筛选大豆cDNA文库,获得一抗病基因同源cDNA片段,命名为KR3-1。根据KR3-1设计两个基因特异引物(GSP 和 NGSP),分别与通用引物(UPM)和巢式通用引物(NUP)共同扩增,成功地克隆到了该基因的5′末端序列。该扩增片段长447 bp,与已知序列重叠部分为129 bp。
Abstract:Based on part of a known partial cDNA sequence of a disease resistance gene homolog,KR3-1,obtained by screening a cDNA library from soybean,5′-RACE-PCR was carried out with gene specific primers and universal primers.After the nested PCR reaction,an amplified fragment of 447 bp in length which overlapped the known KR3-1 sequence by 129 bp was obtained subsequently.Thus,a 5′ cDNA end of KR3 was successfully cloned. 相似文献
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Tim D. Shafman Matthew L. Sherman Donald W. Kufe 《Biochemical and biophysical research communications》1984,124(1):172-177
The polyamines putrescine, spermidine and spermine have been implicated in the regulation of proliferation and differentiation. The present study has monitored the effects of 5′-methylthioadenosine, the metabolic product of spermidine and spermine synthesis, on the appearance of a differentiated murine erythroleukemia cell phenotype. The results demonstrate that increasing concentrations of 5′-methylthioadenosine (1 × 10?6 to 5 × 10?4M) progressively inhibit murine erythroleukemia cell heme synthesis and hemoglobin production. The results also demonstrate that this inhibition of differentiation is not related to depletion of intracellular spermidine or cytostasis. Since 5′-methylthioadenosine is also a known inhibitor of DNA methylation, this naturally occurring nucleoside may be an intermediate involved in both murine erythroleukemia cell proliferation and differentiation. 相似文献
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Richard Y.-H. Wang Lan-Hsiang Huang Melanie Ehrlich 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,696(1):31-36
Bacteriophage XP-12-infected Xanthomonas oryzae have been found to be a source of a kinase preparation which converts m5dCMP to m5dCDP and then to m5dCTP using ATP as the phosphate donor. Optimal formation of the triphosphate required the presence of creatine phosphate and creatine kinase. In the presence of dGTP, dTTP and dATP, Escherichia coli DNA polymerase I and T4 DNA polymerase catalyzed the incorporation of m5dCTP into DNA just as efficiently as that of dCTP. Neither dTMP nor dCMP served as substrate for the m5dCMP monophosphate kinase. Analogous preparations from uninfected X. oryzae were unable to phosphorylate m5dCMP. 相似文献
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A novel process for producing inosine 5′-monophosphate (5′-IMP) has been demonstrated. The process consists of two sequential
bioreactions; the first is a fermentation of inosine by a mutant of Corynebacterium ammoniagenes, and the second is a unique phosphorylating reaction of inosine by guanosine/inosine kinase (GIKase). GIKase was produced
by an Escherichia coli recombinant strain, MC1000(pIK75), which overexpressed the enzyme up to 50% of the total cellular protein. The overproducing
plasmid, pIK75, which was randomly screened out from deletion plasmids with various lengths of intermediate sequence between
the E. coli trpL Shine-Dalgarno sequence, derived from the vector plasmid, and the start codon of the GIKase structural gene. In pIK75, the
start ATG was placed 16 bp downstream of the trpL Shine-Dalgarno sequence under the control of the E. coli trp promoter. Fermentation of inosine and its phosphorylation were sequentially performed in a 5-l jar fermenter. At the end
of inosine fermentation by C. ammoniagenes KY13761, culture broth of MC1000(pIK75) was mixed with that of KY13761 to start the phosphorylating reaction. Inosine in
the reaction mixture was stoichiometrically phosphorylated, and 91 mM 5′-IMP accumulated in a 12-h reaction. This new biological
process has advantages over traditional methods for producing 5′-IMP.
Received: 7 April 1997 / Received last revision: 18 July 1997 / Accepted: 27 July 1997 相似文献
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《Carbohydrate research》1977,59(2):449-457
A facile, two-step synthesis has been devised for the chemical preparation of 5′-deoxyribonucleosides from the parent nucleosides via the 5′-chloro-5′-deoxy-nucleosides. Treatment of 5′-chloro-5′-deoxynucleosides with tributyltin hydride and α,α′-azobis(isobutyronitrile) in dry tetrahydrofuran yields the corresponding 5′-deoxy-nucleosides. Dechlorination of 5′-chloro-5′-deoxythymidine with tributyltin hydride gives 1-(2,5-dideoxy-β-D-erythro-pentofuranosyl)thymine (5′-deoxythymidine) in good yield. Similarly, dechlorination of 9-(3,5-dichloro-2,3,5-trideoxy-β-D-threo-pentofuranosyl)adenine and 1-(3,5-dichloro-2,3,5-trideoxy-β-D-threo-pentofuranosyl)thymine yields the corresponding two trideoxynucleosides. 相似文献
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目的:克隆并分析抗β淀粉样肽单克隆抗体轻链与重链可变区基因。方法:从分泌抗β淀粉样肽单克隆抗体的杂交瘤细胞株A8中提取总RNA,根据恒定区序列设计基因特异性引物,通过5′RACE法扩增抗体的轻链和重链可变区基因,测定并分析可变区基因序列,并克隆入pMD18-T载体。结果:重链可变区基因序列全长450bp,编码150个氨基酸残基;轻链可变区基因序列全长429bp,编码143个氨基酸残基。在GeneBank中对氨基酸序列进行比对分析,二者均符合小鼠IgG可变区基因的特征。根据Kabat法则对A8抗体轻链和重链可变区氨基酸序列基因进行分析并确定了3个抗原互补决定区(CDR)、4个框架区(FR)和信号肽。结论:通过5′RACE法得到了抗β淀粉样肽单克隆抗体轻链与重链可变区基因,为进一步研究抗体三维结构,以及对该抗体进行人源化改造奠定了基础。 相似文献