鲍鱼多糖Hal-A的热分析研究

采用热重、热重-红外谱联用及差示扫描量热法，对鲍鱼多糖进行热分析研究 ，结果表明鲍鱼多糖在空气和氮气氛中，230 ～ 340 ℃之间发生剧烈的分解反应 。氮气氛中，是吸热的分解过程；而空气氛中，是放热氧化反应，并且在453 ℃左 右，有另一个急剧的氧化裂解过程。与淀粉、肝素、甲壳素和半乳糖的热分析比较 ，含有硫酸酯的鲍鱼多糖和肝素热稳定性较低，含氨基的甲壳素最高，这反映出不 同基团对多糖热稳定性的影响。     

碳水化合物的气相色谱分析——甲基糖苷形成的前处理

近两年来我们已将气相色谱技术应用于碳水化合物的研究中,参考文献中常用的方法,结合我们实验室条件进行了一些探索和总结。在多糖、寡糖的组成分析中,我们常采用甲醇解后以三甲基硅烷(TMS)化甲基糖苷的形式进行气相色谱分析。本文针对甲醇解过程中所用的甲醇-HCl易转化成氯甲烷的现象及甲醇解后如何选用适宜的中和剂等问题进行了研究,系统地测定了不同浓度的甲醇-HCl在甲醇解过程中酸浓度的变化,为甲醇解条件的选择及中和剂的用量提供了依据。最后选用了甲醇-NaOH溶液为中和剂并与其他中和方法进行了比较。同时在80℃用0.5—2.0N甲醇-HCl测定了肝糖原的甲醇解速度。所得结果已满意地应用于有关多糖结构的测定中。     

玉米芯酸提水溶性多糖CCCP的分离纯化和结构研究

玉米芯用PH=3的HCl煮提得到酸提水溶性粗多糖．该粗多糖组成为Glc，Xyl，Gal，经乙醇分级和Sepharose CL-6B柱层析纯化，得到多糖CCCP．经Sephadex A-25柱层析、比旋光度测定、醋酸纤维薄膜电泳等方法鉴定CCCP为均一多糖．经唾液淀粉酶解、纤维素酶解、部分酸水解、高碘酸氧化、Smith降解、甲基化分析及IR，GC和GC／MS等方法分析表明：CCCP为少分枝结构；主链由吡喃型(1→3)Xyl构成，在O(4)处有分枝；支链主要由(1→4)Glc构成，在O(6)处有分枝，支链还存在1→3，1→6键型连接的Glc，Gal；末端基为Xyl，Glc，Gal．     

专利

用于多糖的定性与定量分析方法公开号:CN101539550公开日:2009.09.23申请人:李绍平摘要用于多糖的定性与定量分析方法,(1)多糖的酶解及验证:多糖水溶液以比色法测定含量;(2)经HPSEC-ELSD分析,比较酶解前、后多糖图谱的变化;(3)多糖酶解液中糖类成分直接HPLC分析或柱前衍生化后HPLC分析;以标准单糖、糖醛酸、双糖等为对照和以色谱峰质荷比为参比,进行糖谱色谱峰识别;其稳定的特征片段,则用作定量分析指标;(4)通过上述各步骤的独立或联合应用,构建基于结构信息的多糖酶解响应特征和多糖酶解糖谱,实现对多糖的定性、定量分析。此法可用于人参、三七、西洋参、冬虫夏草、蛹虫草、赤芝、紫芝、黄芪和当归等中药多糖的鉴别和定量测定,为多糖及其产品的质量控制提供了有效的方法。一种同时检测牛奶中多种酞酸酯的测定方法公开号:CN101551363公开日:2009.10.07申请人:江南大学摘要一种同时检测牛奶中多种酞酸酯的液质联用(LC-ESI-MS/MS)测定方法,属于食品检测技术领域。本发明牛奶样品用乙腈和氯化钠直接提取;液相色谱分离采用甲酸醋酸铵水溶液-甲醇体系作为流动相,梯度洗脱;质谱检测器检测,采...     

白芷多糖的分析

研究了白芷多糖的结构和单糖组成。采用紫外光谱和红外光谱法对白芷多糖进行定性分析。结果表明,白芷多糖具有多糖特征性的紫外和红外吸收峰,其分子中存在酰胺结构;凝胶渗透色谱法测定结果表明,白芷多糖的峰值分子量为88538;采用气相色谱法测定白芷多糖中单糖的种类和构成比例,结果表明,白芷多糖由鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖等7种单糖组成,并计算出其中6种单糖的摩尔组成比例。     

基于模型化合物反应路径解析淖毛湖褐煤萃取残渣的甲醇醇解机理

以淖毛湖褐煤(NL)超声辅助萃取残渣(ER)作为研究对象,在300℃下采用甲醇对ER进行醇解,并考察添加KOH对醇解过程的影响.通过GC-MS分析MP(未添加KOH)和MPKOH(添加KOH)两种醇解产物的组成信息.选取苯甲酸苄酯(BB)和乙酸苯酯(PA)作为ER的两种模型化合物(MER),醇解后得到产物BBP、BBP...     

不同加工方式对鹿茸中水溶性多糖含量及单糖组成的影响

采用水提醇沉法提纯鹿茸中的水溶性多糖，苯酚-硫酸法测定其含量；多糖经水解、衍生后通过UPLC分析不同加工方式及不同部位鹿茸中单糖组成及含量的差异。结果表明，煮炸茸蜡片、粉片、纱片、骨片中水溶性多糖含量分别为1.74、1.67、1.03和1.13 g/kg，冻干茸为2.77、3.07、1.22和3.20 g/kg；排血茸4个部位水溶性多糖含量依次为1.55、1.78、0.96和0.77 g/kg，带血茸为1.69、1.64、1.01和1.31 g/kg。不同加工方式鹿茸中水溶性多糖单糖组成均检出甘露糖、氨基葡萄糖、核糖、葡萄糖醛酸、半乳糖醛酸、氨基半乳糖、葡萄糖和半乳糖8个组分，对于同一部位，煮炸茸单糖含量低于冻干茸，排血茸单糖（氨基葡萄糖和氨基半乳糖除外）含量低于带血茸；对于同一加工方式不同部位，表现出蜡片、粉片高于纱片、骨片。研究加工方式对鹿茸中水溶性多糖含量及单糖组成的影响，以期为鹿茸加工及其产品开发提供理论参考。     

稻子、小麦麸皮中可溶性非淀粉多糖的气相色谱法测定

讨论稻子、小麦麸皮中可溶性非淀粉多糖的气相色谱法测定。将稻子、小麦麸皮磨细后,用８０％乙醇萃取游离糖,剩余物在醋酸缓冲液（ｐＨ５．０）条件下分别用α－淀粉酶和α－葡萄糖苷酶酶解,除掉淀粉。非淀粉多糖用酸水解为各单糖,采用糖醇衍生化成乙酸酯的制备方法,用ＯＶ－１７０１石英毛细管色谱柱,可分离得到非淀粉多糖（ＮＳＰ）各组成单糖的色谱峰。并以自然界中不存在的阿洛糖作内标物,提高了定性定量分析的准确性,计算出了稻子、小麦麸皮中可溶性非淀粉多糖的含量。     

海藻多糖的组成及结构光谱分析

海藻多糖具有抗凝血等多种生物活性,其活性与多糖的组成结构有关。本文对近年来红藻、褐藻及少量绿藻多糖的单糖组成及含量研究以及FT-IR和12^C NMR两种主要光谱手段对多糖结构研究的结果进行了介绍。     

铁皮石斛中石斛多糖与石斛碱的纤维素酶法提取研究

本文利用纤维素酶法联合提取铁皮石斛中的多糖与生物碱,通过单因素实验研究酶用量、酶解时间、酶解温度和酶解pH对石斛多糖与生物碱收率的影响.实验结果表明,在本实验范围内,最佳提取工艺为:纤维素酶用量为原料的0.6%(质量分数),酶解时间为1.5h,酶解温度为50℃,酶解pH值等于5.0.在此工艺下,石斛碱的收率达19%,石...     

Haloduracin α binds the peptidoglycan precursor lipid II with 2:1 stoichiometry

The two-peptide lantibiotic haloduracin is composed of two post-translationally modified polycyclic peptides that synergistically act on gram-positive bacteria. We show here that Halα inhibits the transglycosylation reaction catalyzed by PBP1b by binding in a 2:1 stoichiometry to its substrate lipid II. Halβ and the mutant Halα-E22Q were not able to inhibit this step in peptidoglycan biosynthesis, but Halα with its leader peptide still attached was a potent inhibitor. Combined with previous findings, the data support a model in which a 1:2:2 lipid II:Halα:Halβ complex inhibits cell wall biosynthesis and mediates pore formation, resulting in loss of membrane potential and potassium efflux.     

Reactions of a stable silylene with halocarbons

An unusual product formation is observed for the insertion reaction of the thermally stable silylene Si[(NCH(2)Bu(t))(2)C(6)H(4)-1,2][abbrev. as Si(NN)] into the carbon-halogen bond of alkyl or aryl halides RHal (Hal=Cl, Br). In general, depending on the halogen, the reaction either results in a disilane of type (NN)Si(Hal)-(R)Si(NN) for Hal=Cl or a mixture of disilane and the monosilane (NN)Si(R)(Hal) for Hal=Br. The results are put into context to previously suggested mechanisms. The disilane (NN)Si(Hal)-(R)Si(NN)(Hal=Cl or Br) is thermally labile and mild thermolysis yields the corresponding monosilane (NN)Si(R)(Hal) and silylene 1. Additionally, strong evidence is presented for a radical pathway for the reaction of 1 and RHal.     

Palladated cyclodextrin and halloysite containing polymer and its carbonized form as efficient hydrogenation catalysts

β‐Cyclodextrin (β‐CD) and glycidyl methacrylate monomer were polymerized in the presence of functionalized halloysite nanoclay (Hal) to afford a polymeric network (Hal‐P‐CD) containing Hal and CD. Hal‐P‐CD was then applied as a catalyst support for the immobilization of Pd nanoparticles. The resulting nanocomposite, Pd@Hal‐P‐CD, could serve as a catalyst for the hydrogenation of nitrobenzene. The precise study by the preparation of control samples confirmed the contribution of CD as both phase transfer and capping agent, P (polymer) and Hal to the catalysis. Moreover, the results confirmed the importance of CD: glycidyl methacrylate monomer ratio. Pd@Hal‐P‐CD was also carbonized to prepare Pd@Hal‐C. Notably, the characterization of Pd@Hal‐C showed that carbonization led to the growth of mean diameter of Pd nanoparticles, increase of Pd content and partial destruction of Hal. However, the catalytic activity of Pd@Hal‐C was superior to Pd@Hal‐P‐CD. Pd@Hal‐C was also highly recyclable and could be recovered and recycled for several reaction runs. The study of the carbonization temperature showed that this factor affected the nature of the resulting carbon and the catalyst prepared at elevated temperature showed higher catalytic activity.     

Na,Ba∥F,Br three-component reciprocal system and analysis of the Na,Ba∥F,Hal (Hal=Cl, Br, and I) series

A set of isopleths was studied using differential thermal analysis (DTA), the liquidus surface projection on the concentration square was plotted, and parameters were determined for the alloys corresponding to two ternary eutectics and one peritectic of the Na,Ba∥F,Br three-component reciprocal system. Solid-phase reactions in a sample containing 66.7% BaBr2+33.3% (NaF) ₂ were also studied by DTA. The results were used to analyze the entire series of the Na,Ba∥F,Hal (Hal = Cl, Br, and I) systems.     

Haloacyl complexes of boron, [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I)

The haloacyltris(trifluoromethyl)borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been synthesized by reacting (CF3)3BCO with either MHal (M=K, Cs; Hal=F) in SO2 or MHal (M=[nBu4N]+, [Et4N]+, [Ph4P]+; Hal=Cl, Br, I) in dichloromethane. Metathesis reactions of the fluoroacyl complex with Me3SiHal (Hal=Cl, Br, I) led to the formation of its higher homologues. The thermal stabilities of the haloacyltris(trifluoromethyl)borates decrease from the fluorine to the iodine derivative. The chemical reactivities decrease in the same order as demonstrated by a series of selected reactions. The new [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br) salts are used as starting materials in the syntheses of novel compounds that contain the (CF3)3B-C fragment. All borate anions [(CF3)3BC(O)Hal]- (Hal=F, Cl, Br, I) have been characterized by multinuclear NMR spectroscopy (11B, 13C, 17O, 19F) and vibrational spectroscopy. [PPh4][(CF3)3BC(O)Br] crystallizes in the monoclinic space group P2/c (no. 13) and the bond parameters are compared with those of (CF3)3BCO and K[(CF3)3BC(O)F]. The interpretation of the spectroscopic and structural data are supported by DFT calculations [B3LYP/6-311+G(d)].     

Homopolycondensation of 1-halogenopropane-2-thiones

Homopolycondensation of 1-halogenopropane-2-thiones was studied; the polymers obtained were structurally characterized by ESR, UV, and IR spectroscopy, elemental analysis, and electrochemical methods. Their molecular masses, dark conductivities, and photoconductivities were determined. The capability for film formation on various substrates was investigated. These polymers were found to be new organic metals (Hal=I), semiconductors (Hal=Cl and Br), and photoconductors (Hal=Cl, Br). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 330–333, February, 2000.     

The Origin of the Halogen Effect on the Phthalocyanine Green Pigments

The structure and the electronic and optical properties of halogenated copper‐phthalocyanine (nα,mβ(Hal)‐CuPc) molecules are investigated, according to the variation in the substituted halogen‐atom species (Hal=Cl or Br) at the α and β positions of isoindole ring with different numbers (n and m=0, 4, 8, or 16). Our results show that the halogen effect mainly results from a structural deformation rather than caused by electronic effects. A nonplanar deformation of the phthalocyanine chromophore of the nα,mβ(Hal)‐CuPc molecule causes a significant change only in the HOMO and HOMO‐1 levels, rather than in the LUMO levels, which leads to the appearance of a green color arising from the large red‐shifts of the Soret and Q bands. The present result may serve as an important reference point for designing novel halogen‐free green pigments, in accordance with the environmental regulations for the restriction of hazardous substances (RoHS) in electronic and electrical devices.     

Isostructural and Nonisostructural Compounds in Series of Halogenated Organic Crystal Substances. Structure of Hal-Aggregates

The local characteristics and the form of intermolecular Hal aggregates (assemblies of contacting halogen atoms of neighboring molecules), existing in haloorganic crystal substances differing only in the nature of Hal atoms, are compared. Twenty three series of halogenated hydrocarbons involving 57 crystal structures are considered. Pronounced specifics of Hal-aggregates has been established for compounds with low and medium halogen contents. It is found that k(Hal) (coordination number of the Hal atom with respect to the neighboring Hal atoms) generally increases in the series F–Cl–Br–I; for constant k(Hal), <> = i - 2R_Hal> nearly always decreases (r_i is the distance from the Hal atom in question to one of the k nearest Hal atoms, and R _Hal is the van der Waals radius).     

Trans-Strengthening in tin(IV) anionic complexes

X-Ray studies of (NMe₄)₂EtSnCl₅, (NMe₄)₂BuSnBr₅ and (NMe₄)₂SnBr₆ indicate octahedral geometry for all the tin atoms. In the first two complexes, under the influence of the alkyl group, the cis-Sn—Hal bonds are lengthened by 0.11 Å (Hal = Cl) and 0.09 Å (Hal = Br), while the trans-Sn—Hal bonds are shortened by 0.03 Å (Hal = Cl) and 0.05 Å (Hal = Br).     

Lasagna-type arrays with halide-nitromethane cluster filling. The first recognition of the Hal(-)···HCH2NO2 (Hal = Cl, Br, I) hydrogen bonding

The previously predicted ability of the methyl group of nitromethane to form hydrogen bonding with halides is now confirmed experimentally based on X-ray data of novel nitromethane solvates followed by theoretical ab initio calculations at the MP2 level of theory. The cationic (1,3,5-triazapentadiene)Pt(II) complexes [Pt{HN=C(NC(5)H(10))N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [1](Hal)(2) (Hal = Cl, Br, I), and [Pt{HN=C(NC(4)H(8)O)N(Ph)C(NH(2))=NPh}(2)](Cl)(2), [2](Cl)(2), were crystallized from MeNO(2)-containing systems providing nitromethane solvates studied by X-ray diffraction. In the crystal structure of [1][(Hal)(2)(MeNO(2))(2)] (Hal = Cl, Br, I) and [2][(Cl)(2)(MeNO(2))(2)], the solvated MeNO(2) molecules occupy vacant spaces between lasagna-type layers and connect to the Hal(-) ion through a weak hydrogen bridge via the H atom of the methyl thus forming, by means of the Hal(-)···HCH(2)NO(2) contact, the halide-nitromethane cluster "filling". The quantum-chemical calculations demonstrated that the short distance between the Hal(-) anion and the hydrogen atom of nitromethane in clusters [1][(Hal)(2)(MeNO(2))(2)] and [2][(Cl)(2)(MeNO(2))(2)] is not just a consequence of the packing effect but a result of the moderately strong hydrogen bonding.