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甘露聚糖肽的结构鉴定 总被引:1,自引:0,他引:1
采用离子交换柱层析和凝胶柱层析从甘露聚糖肽原料中分离纯化得到4种均一糖肽MT1-A,MT1-B,MT2-A和MT2-B;通过单糖组成分析、甲基化分析、氢核磁共振谱(~1H NMR)、红外光谱(IR)和氨基酸组成分析等手段对均一糖肽MT1-A,MT1-B和MT2-B的结构进行了鉴定.结果表明,3种均一糖肽的单糖组成、糖残基的连接方式与MT2-A相同,但是分子量以及氨基酸总量有所不同.测定了不同批次甘露聚糖肽原料的~1H NMR谱,以MT2-A的~1H NMR谱图为标准谱,以异头氢区域为鉴定区域,通过计算不同批次甘露聚糖肽原料以及其它3种均一糖肽与MT2-A的~1H NMR谱的相关系数,定量评价了不同批次甘露聚糖肽原料与4种均一糖肽的相似程度.结果表明,甘露聚糖肽是由糖链结构一致、分子量和氨基酸含量不同的几种均一糖肽构成的混合物. 相似文献
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具有免疫促进作用的螺旋藻多糖SP-4的研究 总被引:5,自引:0,他引:5
从螺旋藻NaHCO3热水提取液中.得到四种多糖SP-1、SP-2、SP-3和SP-4,糖含量比为30:12:16:100.体外活性试验表明SP-4能促进T淋巴细胞的增殖.纸层析和高压液相色谱分析结果表明SP-4由L-鼠李糖、L-岩藻糖、L-阿拉伯糖、D-葡萄糖、D-葡萄糖胺和D-半乳糖醛酸组成,其摩尔比为4.94:2.99:2.96:1.00:1.26:2.33。IR光谱示848cm-1有明显的吸收峰,1HNMR分析在δ5.26附近有多个峰,过碘酸盐氧化和Smith降解表明SP-4分子中含有α(1→3)和α(1→4)糖苷键. 相似文献
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芦荟多糖的分离纯化及结构分析 总被引:18,自引:0,他引:18
以库拉索芦荟(Aloebarbadensismiller)为材料,经热水抽提,乙醇分级沉淀得2种酸性多糖PSA1和PSA2,用酶法和Seveg法去除蛋白质.经纸层析和Sephadex凝胶柱层析,证实均为单一组分.经薄层层析和乙酰化GC/MS分析表明,多糖PSA1由甘露糖和葡萄糖组成,摩尔比为1:1.3.多糖PSA2主要由甘露糖组成,经红外光谱及核磁共振证明了PSA2为部分乙酰化的甘露聚糖.经过改良的Hakomori甲基化,高碘酸氧化和Smith降解分析表明均为1→4连接,有少量的1→6连接,是分支较少的直链多糖. 相似文献
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采用循环伏安法和紫外光谱法对有机物的光催化降解进行机理研究和在线监测.以标准光催化剂DegussaP25在紫外光照射下催化降解4-氯苯酚,发现在降解过程中至少有两对氧化还原中间产物:对苯二酚-苯醌和羟基氢醌-羟基苯醌.由4-氯苯酚及中间产物的电极响应,可以观测到它们在光催化降解过程中的含量变化,从而对整个过程实现在线监测,并由此全面了解光催化反应机理.从不同反应时间后测得的紫外光谱可以看到,苯环特征峰逐渐消失.这表明4-氯苯酚的苯环逐渐被打开,直至被彻底降解. 相似文献
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设计合成了1,1'-(2,5-噻二唑-二硫乙酰基)4,4'-(对氯苯甲酰基)氨基硫脲,并用紫外光谱研究了其对阴离子客体的识别性能。主体1加入到对硝基酚氧阴离子(p-NO2C6H4O^-)的DMSO溶液中,主客体间形成超分子配合物使得客体阴离子425nm处吸光度降低且溶液从黄色变为无色。受体1与F,CH3COO^-,H2PO4^-相互作用,吸收光谱也发生一定变化,而与Cl,Br,I,HSO4^-,NO3^-作用,吸收光谱几乎没有变化。其吸收光谱改变强弱顺序为p-NO2C6H4O〉F〉CH3COO〉H2PO4^-〉〉Cl^-,Br,I,HSO4^-,NO3^-。紫外光谱滴定的结果经非线性拟合,表明主客体间形成1:1络合物,并且计算出受体与阴离子结合的稳定常数。质子溶剂效应进一步证明了受体分子与阴离子之间以氢键作用方式相结合。基于实验结果,对主客体之间的作用机理及识别模式作了初步探讨。 相似文献
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稀土钼钒磷杂多酸半菁盐的合成,表征和催化性能 总被引:2,自引:0,他引:2
用降解法首次制得Dawson结构的稀土钼钒磷酸钾。通过它们与溴化(E)-1-丁基-4-[2-(4-二甲氨基苯)乙烯基]吡啶反应,制备了种未见文献报道的具有下列组成的新型稀土杂多配合物的有机衍生物,研究了其红外、紫外,可见光谱、X射线光电子能谱、X射线粉末衍射及热重-差热谱,以镧配合物为催化剂,对乙酸与正丁醇、异戊醇的酯化反应进行了初步研究。 相似文献
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Xiao Wang Kena Li Ming Yang Jingfeng Wang Junhua Zhang 《Cellulose (London, England)》2017,24(1):35-47
During the pretreatment of lignocellulosic materials, the dissolved mannan would re-adsorb on cellulose, and then inhibited the cellulose hydrolysis by cellulases. However, the adsorption of mannan on cellulose and hydrolyzability of mannan adsorbed on cellulose were not so clear. In this work, the adsorption behavior of mannans on cellulose and the hydrolysis of adsorbed mannan by mannanase were investigated. Adsorption of 1, 4-β-D-mannan (mannan), Konjac glucomannan (GM), and Carob galactomannan (GalM) on Avicel and corn stover (CS) was increased with mannan loading. The adsorbed amount of mannan (94.4 mg/g Avicel and 85.1 mg/g CS) on cellulosic substrates at the mannan concentration of 5 mg/mL was significantly higher (p < 0.05) than that of GM (65.7 mg/g Avicel and 63.7 mg/g CS) and GalM (44.3 mg/g Avicel and 48.7 mg/g CS). Furthermore, the NMR spectra and molecular weight analysis showed that mannan with less side groups and low molecular weight might increase the adsorption. Mannan, GM, and GalM adsorbed on Avicel and CS, which was used as Avicel/CS -mannan/GM/GalM complex, could be hydrolyzed by mannanase, and the hydrolyzability of Avicel-mannan/GalM complexes was stronger than that of Avicel-GM complex. Similarly, the reducing sugars increased by 23.2 and 54.2 % for Avicel-mannan and Avicel-GalM complexes after 48 h hydrolysis by cellulase and mannanase, respectively. The results suggested that the addition of mannanase could hydrolyze the mannan adsorbed on cellulose and potentially improved hydrolysis efficiency of cellulose in lignocelluloses. Additionally, the mannanase supplementation could be extended to the removal of mannan on pulp by mannanase and finally affecting the dissolving pulps and paper quality. 相似文献
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巴戟天中一种多糖的分离与结构表征 总被引:2,自引:0,他引:2
以巴戟天的根为原料, 经热水浸提、Sevag法除蛋白、乙醇沉淀和DEAE-Sepharose CL-6B离子交换柱层析, 得到一种水溶性的巴戟天多糖(MOPI-3). 通过UV、IR、NMR、GC-MS、高碘酸氧化、Smith降解和甲基化等物理化学方法对MOPI-3的纯度、理化性质和组成结构进行表征. 结果表明, MOPI-3分子量为36061, 是一种由阿拉伯糖、半乳糖和葡萄糖组成的杂多糖, 以α-1,3-吡喃葡萄糖和α-1,4-吡喃半乳糖为主链, 平均每5个葡萄糖连接一个半乳糖, 每个重复单元具有一个支链, 支链由3个呋喃阿拉伯糖以α-1,3-键型组成, 连接在主链葡萄糖的6位碳上, MOPI-3含有乙酰基, 连接在主链半乳糖的2位碳原子上. 相似文献
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In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysisor partially hydrolysis, the derivatives have obvious antitumor activities. The decreasein molecular weight of glucans after periodate modification hardly affects their antitumoractions, but on the other hand, the decrease of molecular weight without periodate modi-fication could lead to an enhancement of the antitumor activities. Moreover, the glucansand these derivatives have much higher enhancement ratios of body weight of mice thanthat of 5-Fluorouracil (5-Fu), suggesting that they are less toxic than 5-Fu. 相似文献
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S Sarkar 《Journal of supramolecular structure》1977,6(4):617-632
Rabbit antibodies to cell wall mannans of various microbial strains and their mutants were found to be cross-reactive to cell carbohydrates of mammalian sperm and 4-6-days-old blastocysts. Immunochemical studies indicate that oligomers of alpha1 yields to 2, alpha1 yields to 3, alpha1 yields to 6, and probably also alpha yields to 4 linked mannose residues of sperm carbohydrates are available for antibody binding. At least 80 percent of binding activity of a yeast mannan antibody to sperm can be effectively inhibited by specific haptens or digestion with exo-alpha-D-mannosidase, an enzyme activity highest in testicular tissue. In order to determine the role of this enzyme in the metabolism of the cross-reactive mannan antigens of sperm, the relative amount of a specific alpha-linked oligomannosyl determinant of bovine sperm from homozygous normals was compared to that of hetero-zygous carriers of alpha-mannosidase deficiency. Extensive cross-reactivity between the microbial and mammalian oligomannosyl determinants suggest that these are conserved structures in cell carbohydrates, although the organization of these units in the microbial cell wall lipopolysaccharide has very little similarity to the carbohydrate moieties of mammalian glycoproteins. 相似文献
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N. Frank H. Friebolin G. Keilich J. P. Merle E. Siefert 《Magnetic resonance in chemistry : MRC》1972,4(5):725-732
H-NMR investigations using a high resolution 220 MHz spectrometer were performed on methyl, acetyl and benzoyl derivatives of mannan from ivory nuts and Tubera salep, and on the corresponding d-mannopyranose derivatives. With the exception of the C(1) configuration the structure of these polysaccharides may be determined by comparing the coupling constants and chemical shifts of the substituted polysaccharides with those of the corresponding monosaccharide derivatives. The particularly broad signals in the spectra of low as well as high molecular weight acetyl and benzoyl mannans and furthermore, the differences between the chemical shifts of protons in 1,2,3,4,6-penta-O-acetyl-d-mannopyranose and those of the benzoylated mannans, are discussed in terms of relatively small flexibility of the polymer chains or chain segments in solution. In addition studies to determine the type of glycosidic bonds in polysaccharides from a comparison of the δH(1)-values of various polyglycan derivatives are reported. 相似文献
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榆耳水溶性多糖GIA的结构分析 总被引:7,自引:0,他引:7
用6%尿素从榆耳(Gloeostereuminsarnatum)子实体中提取出水溶性粗多糖,经乙醇分级及SeoharoseCL-6B制备柱收集得到组分GIA.经SephadexG-75、DEAE-阴离子交换纤维素和HPLC验证,GIA分子量及极性为均一组分.气相色谱(GC)分析表明,其单糖组成为Xyl,Gal和Glc.HPLC测得平均分子量为18000.经IR、GC、部分酸水解、高碘酸氧化、Smith降解、13CNMR、甲基化分析及其产物的GC-MS联机分析表明,GIA为少分支结构,主要由α型糖苷键构成,少部分由β型糖苷键构成;主体结构由Gal和Glc组成,其中主要为Gal1→6,还有Glc1→6;Gal1→6和Glc1→6在3-O处有分支;平均每10个己糖残基有2个分支;GIA的支链部分由Gal1→3和Glc1→3构成;末端残基为Xyl,Gal,Glc. 相似文献
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M. A. Khodzhaeva Z. F. Ismailov E. S. Kondratenko A. S. Shashkov 《Chemistry of Natural Compounds》1982,18(1):20-24
By fractionating the total glucofructan from the bulbs ofAllium sativum L. a homogeneous glucofructan with a molecular weight of 2300 has been isolated. On the basis of its characteristics, a comparison of IR and13C NMR spectra, and the results of periodate and chromium trioxide oxidation and of methylation, it has been established that this glucofructan is a new type of compound of this class, containing both inulin (2 → 1) and levan (2 → 6) glycosidic bonds. 相似文献
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Characterization of a polysaccharide having activity on the reticuloendothelial system from the stolon of Glycyrrhiza glabra var. glandulifera. 总被引:1,自引:0,他引:1
An acidic polysaccharide, named glycyrrhizan GA, was isolated from the stolon of Glycyrrhiza glabra L. var. glandulifera Reg. et Herd. It produced a single band on electrophoresis and a single peak on gel chromatography, and its molecular mass was estimated to be 85,000. Glycyrrhizan GA is composed of L-arabinose: D-galactose: L-rhamnose: D-galacturonic acid: D-glucuronic acid in the molar ratio of 22:10:1:2:1, in addition to small amounts of O-acetyl groups. Part of the hexuronic acid residues exist as methyl esters. Methylation analysis, carbon-13 nuclear magnetic resonance and periodate oxidation studies indicated that its structural features include mainly alpha-arabino-beta-3,6-galactan type structural units. Glycyrrhizan GA showed remarkable reticuloendothelial system-potentiating activity in a carbon clearance test. 相似文献