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Luduvico I Couri MR dos Santos LJ Prado MA Gil RP Alves RB 《Carbohydrate research》2008,343(3):536-540
Several novel N-1, N-2, and S-5 tetrazole and 1,3,4-oxadiazole derivatives of alpha,alpha-trehalose disubstituted at C-6,6', with potential synthetic and pharmacological interest were prepared from commercial tetrazoles and 1,3,4-oxadiazoles in reaction with hexa-O-benzyl-6,6'-di-O-triflyl-alpha,alpha-trehalose. 相似文献
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alpha,alpha-Trehalose 2-sulfate, the core carbohydrate of sulfatides of Mycobacterium tuberculosis, and the 3-sulfate isomer were synthesized by sulfation of 4,6:4',6'-di-O-benzylidene-alpha,alpha-trehalose with pyridine-sulfur trioxide complex to give the 2- and 3-sulfates, which were separated by column chromatography. The ammonium 2-sulfate salt wa was identical with the natural product obtained from the principal sulfatide (SL-I) of M. tuberculosis. 相似文献
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In this work, we describe the synthesis and NMR characterization of four mono- and four dideoxygenated analogs of alpha,alpha-D-trehalose. The symmetrical (2,2'-, 3,3'-, 4,4'- and 6,6'-) dideoxy analogs were obtained via selective protection and subsequent radical deoxygenation of the desired hydroxyl group set. The unsymmetrical (2'-, 3'-, 4'- and 6'-) monodeoxy analogs were synthesized by desymmetrization of alpha,alpha-trehalose and subsequent deoxygenation under radical conditions. Complete assignment of all (1)H and (13)C resonances in the spectra of these deoxytrehaloses was achieved through the extensive use of 2D [(1)H,(1)H] and [(1)H,(13)C] correlation NMR experiments. The synthesis of these trehalose analogs sets the stage for future biochemical and NMR-based studies to probe the substrate interactions of trehalose with the recently identified mycobacterial sulfotransferase Stf0. 相似文献
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A non-reducing disugar and amino acid were isolated in the studies on the structure of parvulomycin. The acid hydrolysis of the disugar revealed the presence of 2 moles of D-glucose. Acetylation of the disugar resulted in formation of octa-O-acetyl-alpha,alpha-tregalose, saponification of which resulted in formation of alpha,alpha-tregalose. Its physical parameters, i.e. melting point of the mixed sample, optical rotation, IR-spectrum coincided with those of the authentic alpha,alpha-tregalose. The isolated amino acid proved to be L-glutamic acid on thin-layer chromatography with witness and comparison of the physico-chemical properties of their hydrochlorides. 相似文献
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Effects of humidity were investigated on de- and rehydration behavior of alpha,alpha-trehalose dihydrate (T(h)) throughout simultaneous measurements of differential scanning calorimetry and X-ray diffractometry (DSC-XRD) and simultaneous thermogravimetry and differential thermal analysis (TG-DTA). When T(h) was heated from room temperature under dry nitrogen atmosphere, a metastable anhydrous crystal (T(alpha)) was formed at 105 degrees C after dehydration of T(h). The resulting T(alpha) melted at 125 degrees C and became amorphous, followed by cold crystallization from 150 degrees C giving rise to a stable anhydrous crystal T(beta). Under a highly humid atmosphere, on the other hand, T(beta) was formed at 90 degrees C directly as a result of T(h) dehydration. T(alpha) was readily rehydrated and turned back to T(h) when nitrogen gas with low water vapor pressure of 2.1kPa was admitted, whereas high water vapor pressure up to 7.4kPa was required for rehydration of T(beta) into T(h). This study provided a picture of pathways that link various solid forms of trehalose, taking into account the effects of a humid environment. 相似文献
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The tumour promotor tetradecanoyl phorbol acetate (TPA) inhibited the Mg2+-, Ca2+- and (Na+-K+)ATPases of rat-liver plasma membranes. A nonpromoting phorbolester derivative was without effect. Colchicine and/or vinblastine inhibited the (Na+-K+)ATPase, glucagon-stimulated adenylate cyclase, and cyclic adenosine-3, 5-monophosphate (c-AMP) phosphodiesterase, but were without significant effect on the Mg2+- or Ca2+-ATPase. Cytochalasin B inhibited the (Na+-K+)ATPase. The results furnish the first direct evidence that these drugs may interact with plasma membranes. The mechanism of the enzyme inhibitions is briefly discussed. 相似文献
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描述了中国云南姜科Zingiberaceae一新种——苍山象才参Roscoea cangshanensisM.H.LUO,X.F.Gao&H.H.Lin。该种与大理象牙参R.forrestii Cowley在体态上相近,但唇瓣深裂成2裂片,每个裂片再2裂,基部收缩成具白色条纹的柄,叶片较狭窄,(2-)7-24×1.5-2.5cm,叶片基部狭缩成叶柄状而不同。该新种叶片基部狭缩成叶柄状,唇瓣倒卵状楔形,长2.5-3.5cm,宽2.5-3.0cm,基部收缩成具白色条纹的柄,与长柄象牙参R.debilis Gagnep.相似,但苞片非管状,较短,长5-15mm,隐藏于叶鞘内,花冠管较长,10-12.5cm,唇瓣深裂成2裂片,每个裂片再2裂,可与后者明显区别。 相似文献
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描述了采自中国浙江九龙山的苔类植物一新种——毛茎合叶苔Scapania paraphyllia T.Cao,C.Gao,J.Sun&B.R.Zuo。该新种与腋毛合叶苔S.bolanderiAust.相近,两种皆具带齿叶片和假鳞毛,但新种具如下特征可与腋毛合叶苔区别:(1)植物体小,通常红色;(2)假鳞毛多数,不分枝,不仅生于叶腋,茎上也有着生;(3)背脊为腹瓣长的1/4-1/3,背瓣为腹瓣大小1/2-1/3;(4)叶角质层表面粗糙,具粗瘤,直径达6-8μm。与另一个相似种sampliata Steph.相比,因新种具有粗糙的叶表面和假鳞毛等特征,也易于区别。 相似文献
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Involvement of the phosphotransferase system in galactose transport in Salmonella typhimurium. 总被引:10,自引:0,他引:10
P W Postma 《FEBS letters》1976,61(1):49-53
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Biological markers are normally used to evaluate the candidate of live-attenuated dengue vaccines. D3V 16562 Vero 23 and D3V
16562 Vero 33 which were derivatives of D3V 16562, parental strain, showed the similar biological data. We used molecular
techniques and computational tools to evaluate these derivatives. The nucleotide and amino acid sequences of the derivatives were
compared to their parent. The secondary structures of untranslated regions and B-cell epitopes were predicted. The results showed
that nucleotide substitutions mostly occurred in NS5 and NS5 of V2 was unusual because of amino acid change at 3349 (tryptophan
→stop codon). The nucleotide substitutions in 5''UTR, prM, E, NS1, NS2A, NS3, and 3''UTR were 4, 1, 2, 2, 1, 3, and 2, respectively.
The secondary structure of 5''UTR of V2 was different from P and V1. The secondary structure of 3''UTR of V2 was similar to P and
certainly distinct from V1. Furthermore, B-cell epitopes prediction revealed that there were 21 epitopes of envelope and the
interesting epitope was at position 297-309 because it was in domain III in which the neutralizing antibody is induced. For this
study, the attenuation of derivatives was caused by the nucleotide substitutions in 5''UTR, 3''UTR, and NS5 regions. The genotypic
data and B-cell epitope make the derivatives attractive for the chimeric and peptide DENV vaccine development. 相似文献
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报道了产于中国云南高黎贡山的水龙骨科Polypodiaceae节肢蕨属Arthromeris一新种——贯众叶节肢蕨A.cyrtomioides S.G Lu&C.D.Xu。该新种的植标大小与节肢蕨A .lehmanni(Mett.)Ching相似。但叶片的背面密被绒毛,表面被短柔毛,侧生羽片9-16对。该新种在毛被方面与厚毛羽毛节肢蕨A.tomentosa W.M.Chu相似,但羽片边缘无软骨质的膜质边,侧生羽片多达9-16对。 相似文献
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中国重庆毛茛科银莲花属一新种——涪陵银莲花 总被引:1,自引:0,他引:1
描述了中国重庆市涪陵区的毛莨科Ranunculaceae银莲花属Anemone一新种——涪陵银莲花A.fulingensisW.T.Wang&Z.Y.Liu,并绘出墨线图。根据此新种的总苞苞片无柄,花具4-5枚萼片,花丝丝形,花粉具散沟等特征,可以确定此种应是属于银莲花属鹅掌草组Anemone sect.Stolonifera的一个成员;在该组中,此种以其独特的由2-10个块茎组成的念珠状根状茎而与该组的其他种相区别。鉴于在银莲花属中块茎出现于不同的演化路线中,以及这些块茎的出现系次生现象,可见此新种应是鹅掌草组的进化种。 相似文献
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