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若干双子叶与单子叶植物细胞壁果胶结构单糖组成特征研究 总被引：2，自引：0，他引：2
为了系统研究被子植物初生壁果胶结构单糖的组成成分及其与被子植物两纲分类的关系,结合单糖单一环式的衍生化方法,采用GC/MS测定22种被子植物初生壁果胶中单糖组分及含量,并对测得的结果进行主成分、t检验和香农 威纳指数分析。结果表明:被子植物细胞壁果胶由木糖、鼠李糖、岩藻糖、阿拉伯糖、半乳糖、葡萄糖、甘露糖7种单糖组成,其中鼠李糖、阿拉伯糖和半乳糖含量较高;岩藻糖和甘露糖含量极少。主成分分析筛选出决定22种被子植物间糖含量差异的5种果胶单糖分别为:木糖、阿拉伯糖、半乳糖、鼠李糖和葡萄糖。主成分二维图和t检验结果显示:可通过果胶单糖含量实现被子植物中双子叶和单子叶两纲植物的区分,且木糖和半乳糖决定了两纲间的显著性差异（P＜0.01）。同时香农 威纳指数结果显示了被子植物两纲在单糖含量的多样性上也存在差异,且双子叶植物的单糖多样性显著高于单子叶植物（P＜0.01）。 相似文献
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柱前衍生化HPLC法测定铁皮石斛破壁饮片中甘露糖的含量 总被引：1，自引：0，他引：1
采用柱前衍生化HPLC法测定了12批铁皮石斛破壁饮片中甘露糖的含量。药材采用80%乙醇回流提取除杂后,水煎煮制得石斛多糖,然后将多糖经酸水解为单糖,再用1-苯基-3-甲基-5-吡唑啉酮(PMP)进行衍生化处理,以盐酸氨基葡萄糖作为内标进样测定。结果平均校正因子为0.8248,RSD为0.63%,平均加样回收率为98.03%。每批铁皮石斛破壁饮片中单糖含量存在明显差异,但均符合药典要求。 相似文献
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大球盖菇多糖的分子质量分布及其单糖的组成 总被引：2，自引：0，他引：2
【目的】从大球盖菇(Stropharia rugoso-annulata)中提取多糖,并对其分子质量及组成糖进行研究。【方法】采用水提法提取大球盖菇多糖,利用高效液相色谱法研究大球盖菇多糖分子质量分布及提取过程中多糖分子质量的变化,并采用红外光谱、核磁共振法对其组成糖进行研究。【结果】大球盖菇多糖水溶性多糖类物质的分子质量分布于22 kD附近;大球盖菇多糖同时存在α和β糖苷键,以吡喃糖为主,由5种单糖构成,其中有D-果糖、D-葡萄糖和D-木糖。【结论】以稀盐溶液为流动相的检测手段更能真实地反映大球盖菇多糖的分子质量分布情况,大球盖菇多糖是由5种单糖组成的杂多糖。 相似文献
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柴胡多糖的分子量测定及单糖组成分析 总被引：4，自引：0，他引：4
[目的]从柴胡中提取分离柴胡精多糖（BPP2）,并对其分子量和单糖组成进行研究。[方法]采用水提法提取柴胡精多糖（BP）,用DEAE纤维素柱色谱进行分离纯化,采用GPC法测定BPP2的分子量,TLC、HPLC法对其单糖组成进行研究。[结果]BPP2的分子量约为67836,由鼠李糖（Rha）、木糖（Xyl）、阿拉伯糖（Ara）、半乳糖（Gal）和葡萄糖（Glc）5种单糖组成,其摩尔比为2.19∶1.00∶3.21∶2.27∶2.44。[结论]柴胡多糖BPP2是由5种单糖组成的纯一杂多糖,分子量为67836。 相似文献
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采用水提醇沉法提取6种真菌中的糖蛋白,通过苯酚—硫酸法、间羟基联苯法、BCA法测定其总糖、酸性糖和蛋白质含量,采用PMP柱前衍生化法和HPGPC法测定其单糖组成及分子量分布,采用顺铂建立受损肾细胞模型,研究6种食用真菌糖蛋白的恢复作用。结果表明,香菇糖蛋白的总糖含量最高,为38.11%,口蘑糖蛋白中蛋白质含量最高,为34.21%,各糖蛋白中酸性糖含量均较低且相差不大;6种食用真菌糖蛋白中均含有甘露糖、葡萄糖和半乳糖,其分子量在500~20 000 u之间,在质量浓度为12.5~50 μg·mL-1时6种多糖对受损肾细胞具有一定的恢复作用。理化性质测定结果表明,这6种食用真菌糖蛋白均含有较高的多糖成分,且均对顺铂诱导的肾细胞损伤具有一定的恢复能力。 相似文献
7.
Protein targeting in eukaryotic cells is determined by several topogenic signals. Among these are stop-transfer regions, which halt translocation of proteins across the endoplasmic reticulum membrane. Two different stop-transfer regions were incorporated into precursors for a chloroplast protein, the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Both chimeric proteins were imported into chloroplasts and did not accumulate in the envelope membranes. Thus, the stop-transfer signals did not function during chloroplast protein import. These observations support the hypothesis that the mechanism for translocation of proteins across the chloroplast envelope is significantly different from that for translocation across the endoplasmic reticulum membrane. 相似文献
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大豆连作条件下土壤多糖组成的研究 总被引：1，自引：0，他引：1
土壤多糖是土壤有机质的重要组成部分,我们通过对连作条件下土壤多糖的研究表明,由于连作使土壤多糖的组成发生了较大的变异。从土壤多糖的来源看,随连作时间的延长,微生物多糖逐步增加,而植物性多糖逐步减少。经统计分析表明,组成土壤多糖的单糖根据其性质可分为两类,他们在性质上和来源上有所不同,他进一步证实了以前对土壤多糖组成的分类方法是正确的,同时也为我们的试验提供了数量化的指标。 相似文献
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Platelet membrane glycoprotein IIb/IIIa: member of a family of Arg-Gly-Asp--specific adhesion receptors 总被引：99，自引：0，他引：99
R Pytela M D Pierschbacher M H Ginsberg E F Plow E Ruoslahti 《Science (New York, N.Y.)》1986,231(4745):1559-1562
Adhesive interactions of the platelet surface with plasma proteins such as fibrinogen and fibronectin play an important role in thrombosis and hemostasis. The binding of both of these proteins to platelets is inhibited by synthetic peptides containing the sequence Arg-Gly-Asp, which corresponds to the cell adhesion site in fibronectin and is also present in the alpha chain of fibrinogen. An affinity matrix made of an insolubilized heptapeptide containing the Arg-Gly-Asp sequence selectively binds the platelet membrane glycoprotein IIb/IIIa from detergent extracts of platelets. When incorporated into liposome membranes, the isolated protein confers to the liposomes the ability to bind to surfaces coated with fibrinogen, fibronectin, and vitronectin but not to surfaces coated with thrombospondin or albumin. This platelet receptor is related to the previously identified fibronectin and vitronectin receptors in that it recognizes an Arg-Gly-Asp sequence but differs from the other receptors in its wider specificity toward various adhesive proteins. These results establish the existence of a family of adhesion receptors that recognize the sequence Arg-Gly-Asp. 相似文献
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[目的]建立测定桑枝多糖中单糖的组成及含量的方法.[方法]水提醇沉法提取桑枝多糖,CF3 COOH水解多糖,水解产物用盐酸羟胺、吡啶和醋酸酐衍生化,生成糖腈乙酸酯衍生物,气相色谱法测定桑枝多糖的单糖组成及含量.[结果]新疆桑枝多糖由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖等组成,含量分别为鼠李糖（11.8 mg/ml）、阿拉伯糖（14.4 mg/ml）、木糖（1.6 mg/ml）、甘露糖（1.9mg/ml）、葡萄糖（22.3 mg/ml）及半乳糖（28.0 mg/ml）.[结论]该方法简便、灵敏、准确可靠,可用于桑枝多糖中单糖的组成及含量测定. 相似文献
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A glycoprotein has been extracted in water-soluble form from human red cell membranes with lithium diiodosalicylate. After extraction of the membranes and phosphocellulose chromatography a homogeneous preparation is obtained which was 60 percent carbohydrate and 40 percent protein (by weight). The preparation contains AB and MN blood group antigens, receptors for influenza virus, and various phytohemagglutinins. 相似文献
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枣果实发育过程中游离单糖含量动态研究 总被引：2，自引：0，他引：2
采用HPLC方法和碘量法对冬枣和金丝小枣果实中游离单糖的动态变化进行了测定。结果表明:枣中的游离单糖有葡萄糖、果糖、半乳糖、鼠李糖和阿拉伯糖。在枣果发育的各个阶段均以果糖所占比例最大,其次是葡萄糖和半乳糖,鼠李糖和阿拉伯糖含量很低;果糖、葡萄糖和半乳糖含量在枣果发育前期逐渐增加,临近白熟期达最高值,随果实着色成熟又有所下降;枣果游离单糖中的酮糖只有果糖,醛糖主要为葡萄糖和半乳糖,各约占50%,另有少量的鼠李糖和阿拉伯糖。 相似文献
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Multiple mechanisms of protein insertion into and across membranes 总被引：155，自引：0，他引：155
Protein localization in cells is initiated by the binding of characteristic leader (signal) peptides to specific receptors on the membranes of mitochondria or endoplasmic reticulum or, in bacteria, to the plasma membrane. There are differences in the timing of protein synthesis and translocation into or across the bilayer and in the requirement for a transmembrane electrochemical potential. Comparisons of protein localization in these different membranes suggest underlying common mechanisms. 相似文献
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In creating mitochondria some 2 billion years ago, the first eukaryotes needed to establish protein import machinery in the membranes of what was a bacterial endosymbiont. Some of the preexisting protein translocation apparatus of the endosymbiont appears to have been commandeered, including molecular chaperones, the signal peptidase, and some components of the protein-targeting machinery. However, the protein translocases that drive protein import into mitochondria have no obvious counterparts in bacteria, making it likely that these machines were created de novo. The presence of similar translocase subunits in all eukaryotic genomes sequenced to date suggests that all eukaryotes can be considered descendants of a single ancestor species that carried an ancestral "protomitochondria." 相似文献
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[目的]建立高效液相色谱测定卷烟主流烟气中甘露糖和葡萄糖含量的方法。[方法]采用超声萃取吸附卷烟烟气总粒相物的剑桥滤片,经固相萃取柱纯化,1-苯基-3-甲基-5-吡唑啉酮衍生,高效液相色谱-紫外检测。采用KH2PO4-NaOH(0.05 mol/L,pH=6.8)/乙腈=85/15等梯度洗脱,在HP Hypersil ODS(125×4 mmi.d.,5μm)柱上检测了两种单糖成分。[结果]甘露糖在0.5~8.0μg/ml、葡萄糖在5~50μg/m l范围内线性关系良好(R2>0.999),检测限均为0.14μg/m l(S/N=3),RSD均小于3%,回收率95.8%~99.8%。[结论]该方法能准确地同时检测卷烟烟气中甘露糖和葡萄糖的含量。 相似文献
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Dimethyl sulfoxide prevented loss of respiratory control and decrease in efficiency of oxidative phosphorylation when plant mitochondria were stored in liquid nitrogen. Respiration was severely inhibited and was not stimulated by adenosine diphosphate when mitochondria were frozen in liquid nitrogen without dimethyl sulfoxide. Thus, isolated mitochondria provide a model system for the study of the effects of freezing on biological membranes and of the prevention, by dimethyl sulfoxide, of freezing damage. 相似文献
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研究了金针菇不同菌株、ｐＨ值、淀粉原料、微量元素、多糖的组成单糖、表面活性剂等几个重要因素对金针菇胞外多糖生产的影响．结果表明，供试菌株中以Ｆ－１９产胞外多糖的能力最强；产多糖培养基的最适ｐＨ值为６．５左右；以马铃薯淀粉和甘薯淀粉作碳源，胞外多糖的产量比其他淀粉的高；在培养基中添加质量分数为１００×１０－６－１６０×１０－６的Ｍｎ２＋能显著提高胞外多糖的产量，而添加同等浓度的Ｃｕ２＋反而降低胞外多糖产量．发酵过程中添加胞外多糖的组成单糖中的Ｄ－木糖、Ｄ－甘露糖和Ｄ－阿拉伯糖能显著提高胞外多糖的产量，并以Ｄ－木糖的效果最佳．此外，发酵过程中添加质量比值为５００×１０－６的表面活性剂吐温８０能显著提高胞外多糖的产量． 相似文献
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C A Mannella 《Science (New York, N.Y.)》1984,224(4645):165-166
When outer membranes from Neurospora crassa mitochondria are treated with low levels of phospholipase A2 under continuous dialysis, two-dimensional crystalline arrays of the pore protein component of these membranes are formed. 相似文献
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Li L Lok SM Yu IM Zhang Y Kuhn RJ Chen J Rossmann MG 《Science (New York, N.Y.)》2008,319(5871):1830-1834
Many viruses go through a maturation step in the final stages of assembly before being transmitted to another host. The maturation process of flaviviruses is directed by the proteolytic cleavage of the precursor membrane protein (prM), turning inert virus into infectious particles. We have determined the 2.2 angstrom resolution crystal structure of a recombinant protein in which the dengue virus prM is linked to the envelope glycoprotein E. The structure represents the prM-E heterodimer and fits well into the cryo-electron microscopy density of immature virus at neutral pH. The pr peptide beta-barrel structure covers the fusion loop in E, preventing fusion with host cell membranes. The structure provides a basis for identifying the stages of its pH-directed conformational metamorphosis during maturation, ending with release of pr when budding from the host. 相似文献