银杏种子糖蛋白的SDS-PAGE分离及N-糖链的质谱分析

利用十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)分离了银杏种子中的糖蛋白组分, 进一步用氨水催化释放N-糖链, 并采用电喷雾离子质谱(ESI-MS)及在线液相色谱-质谱联用(LC-UV-MS/MS²)等技术对胶条上释放的N-糖链进行了定性定量分析. 结果表明, 从银杏种子中分离得到11种糖蛋白, 共检测到11条N-糖链, 包括高甘露糖型(4.88%)和复杂型(95.12%) 2种类型, 其中分子量为21000, 36000和50000的糖蛋白所释放的核心α-1,3-岩藻糖和β-1,2-木糖修饰的N-糖链所占比率较高, 分别为68.23%, 64.37%和75.09%. 本研究对进一步研究银杏糖蛋白功能具有重要意义.     

咔唑系列化合物的电极氧化过程

本文研究了咔唑及其几种不同类型衍生物的电极氧化过程.这些衍生物有N-烷基咔唑,如甲基至正庚基、及异丙基咔唑;还有N-不饱和取代基咔唑,如N,-烯丙基、N-苄基、N-乙烯基咔唑;以及N,N'间含有不同烷基的二咔唑.从而得出了这些化合物的电极反应机理.     

脱水糖苷化方法合成肝素酶底物寡糖

乙酰肝素酶（Heparanase,Hpa）是哺乳动物体内的内切葡萄糖醛酸苷水解酶,通过水解葡萄糖醛酸（GlcA）与己胺糖（GlcN）之间的β-糖苷键,选择性地降解肝素和硫酸肝素糖胺聚糖,从而释放多功能的肝素寡糖.本文报道一条高效的肝素酶底物寡糖的合成路线：采用苯甲酰基保护待硫酸化的羟基,苄基保护羧基和裸露的羟基,叠氮基保护氨基,应用脱水糖苷化方法高效地构建关键的a-GlcN-（1→4）-GlcA糖苷键.然后通过标准化的保护基脱除和硫酸化操作,获得肝素酶底物三糖和四糖1-4.最后五步反应的总收率超过52%.肝素酶底物寡糖的合成为研究肝素酶的底物选择性和活性检测打下了基础.     

三氮唑取代杯[4]芳烃配位聚合物的合成与荧光性能

利用四[1-(1, 2, 4-三氮唑基)甲基]间苯二酚杯[4]芳烃配体(TTR4A)在溶剂热的条件下合成了两个配位聚合物,[[Zn₂(TTR4A)(L)₂]·DMF·4H₂O]_n(化合物1) (DMF = N, N-二甲基甲酰胺)和[[Co(TTR4A)Cl₂]·DMA·H₂O]_n (化合物2) (H₂L = 4, 4’-联苯二甲酸) (DMA = N, N-二甲基乙酰胺)。通过单晶X射线衍射方法对这两个配位聚合物的结构进行了确定。利用红外、元素分析、粉末X射线衍射(PXRD)和热重表征手段对化合物1和2进行了表征。在化合物1中,四个L配体连接着四个Zn(Ⅱ)离子形成了环状的Zn₄L₄结构单元,该结构单元进一步地被TTR4A链接形成了一维链状结构。在化合物2中,TTR4A的四个三氮唑基团各连接一个Co(Ⅱ)离子形成二维层状结构。此外,我们对化合物1的荧光性能进行了研究,荧光测定表明固态条件下化合物1发出很强的荧光,并能够选择性地对Fe³⁺、Cr₂O₇²⁻和硝基苯分子产生响应。     

含N-乙酰化肝素寡糖的制备及序列分析

建立了含N-乙酰化肝素寡糖的分离提纯及其序列结构分析方法.首先应用肝素酶Ⅰ深度酶解低分子量肝素来富集含N-乙酰化结构寡糖,通过Bio-Gel P10凝胶色谱法分离制备了包括二糖至十四糖的系列肝素寡糖粗样品,ProPac PA-1强阴离子高效液相色谱(SAX-HPLC)等方法对粗样品进一步分离,提纯得到4种六糖和3种八糖片段.其次应用肝素酶Ⅰ,Ⅱ和Ⅲ复合酶解与HPLC法分析各纯化寡糖的二糖组分,并结合肝素酶Ⅰ底物特异性,初步推断4种六糖和3种八糖的序列结构.在寡糖的糖链两端均含有N-硫酸化二糖,而N-乙酰化二糖分布在糖链当中.应用电喷雾离子阱-飞行时间质谱(ESI-IT-TOF-MS)在负离子模式下进一步表征寡糖并分析其裂解规律.结果表明,各寡糖中均出现大量因SO32-丢失形成的碎片离子峰,六糖中主要有双电荷和三电荷碎片离子峰;在八糖中出现了一系列从双电荷至五电荷的离子峰.各寡糖的双电荷离子峰质荷比进一步确定了上述寡糖的序列结构.六糖的裂解规律表明,裂解主要存在于糖苷键,N-乙酰葡糖胺和糖醛酸上的裂解方式分别为0,2X和0,2Z.本研究提供了切实有效的分离、分析未知结构肝素寡糖序列的新方法.     

基于苯甲酸受体的咔唑染料敏化剂的合成和光电性能

选择N-正丁基咔唑作为电子给体,芴酮作为桥键,苯甲酸作为受体,通过桥键芴酮与给体和受体连接位置的改变,设计合成了两个咔唑染料4-(6-(N-正丁基咔唑-3-基)-9-氧-9H-芴-3-基)苯甲酸(HXL-3W)和4-(7-(N-正丁基咔唑-3-基)-9-氧-9H-芴-2-基)苯甲酸(HXL-4Z).对咔唑染料的光谱性能、电化学性能和光电转换性能进行了研究,并运用密度泛函理论(DFT)方法对其几何结构和紫外-可见光谱进行了优化计算.结果表明, HXL-4Z的吸收光谱呈现两个明显的π→π^*跃迁吸收峰和一个较小的对应于分子内电荷转移的吸收峰,而HXL-3W的吸收光谱则仅呈现一个π→π^*跃迁吸收峰,且摩尔吸光系数远小于HXL-4Z.可能是HXL-3W分子结构中给体和受体距离较近,张力较大,导致较差的分子平面性和分子内电荷转移.因而HXL-4Z的光吸收能力和电子注入效率较优,从而具有较好的光电转换效率(2.03%) (短路电流(J_SC) = 3.88 mA·cm^-2,开路电压(V_OC) = 700 mV,填充因子(FF) = 0.75).     

含硫正离子聚类肽水凝胶的合成与性能

通过伯胺引发肌氨酸-N-硫代羧酸酐(Sar-NTA)和N-烯丙基甘氨酸-N-硫代羧酸酐(NGA-NTA)的开环聚合制备了一种三嵌段聚类肽, 即聚(N-烯丙基甘氨酸)-b-聚肌氨酸-b-聚(N-烯丙基甘氨酸)(PNAG-b-PSar-b-PNAG, 简称PASA); 然后通过PASA侧链上的烯丙基与3,6-二氧杂-1,8-辛烷二硫醇之间的巯-烯“点击”化学反应合成了不同肌氨酸(Sar)摩尔分数的聚类肽水凝胶(HG). 巯-烯“点击”反应生成的大量硫醚基团可进一步与环氧化合物反应, 在水凝胶的网络骨架中生成硫正离子, 从而获得具有固有抗菌能力的含硫正离子聚类肽水凝胶(S⁺HG). S⁺HG具有优异的吸水能力, 能够在1 min内达到吸水平衡, 饱和溶胀率高达2024%. S⁺HG内部由大量规则的连续海绵孔状结构组成, 能够承受一定的剪切、 摩擦及挤压等外界应力. S⁺HG具有强效的广谱抗菌能力, 对革兰氏阴性的大肠杆菌(E. coli)和革兰氏阳性的金黄色葡萄球菌(S. aureus)的抗菌率都在99.99%以上.     

双二苷酰胺从硝酸溶液中萃取Eu(Ⅲ)和Am(Ⅲ)

采用混合酸酐法合成了两种双二苷酰胺(bisdiglycolamide, BisDGA)萃取剂: N,N,N'',N''-四正辛基-N',N″-乙二基-双二苷酰胺(TOE-BisDGA)和N,N,N'',N''-四正辛基-N',N″-间苯二甲基-双二苷酰胺(TOX-BisDGA). 以磺化煤油和正辛醇混合溶液(体积比 90∶10)作稀释剂, 研究了它们在硝酸溶液中对Eu(Ⅲ)和Am(Ⅲ), 以及自身对HNO₃的萃取行为. 结果表明, 2种BisDGAs对HNO₃均有一定萃取, 当酸度不超过1.0 mol/L时, 二者形成1∶1型的萃合物. 随HNO₃浓度增加, Eu(Ⅲ)和Am(Ⅲ)的萃取分配比增加. 相同条件下, TOE-BisDGA对Eu(Ⅲ)和Am(Ⅲ)的萃取能力强于TOX-BisDGA. 斜率分析表明TOE-BisDGA和TOX-BisDGA与Eu(Ⅲ)和Am(Ⅲ)均形成2∶1型的萃合物. 温度升高, 萃取分配比下降, 萃取反应是放热反应. 2种BisDGAs对Eu(Ⅲ)的亲和力强于对Am(Ⅲ)的亲合力, 表明BisDGAs对Eu(Ⅲ)有一定的选择性. 同时, 研究了BisDGAs萃取Eu(Ⅲ)和Am(Ⅲ)的机理, 给出了表观萃取平衡常数和萃取反应热力学函数ΔH, ΔS和ΔG的值. 此外, 还对TOE-BisDGA和TOX-BisDGA与Eu(Ⅲ)形成的配合物进行了红外和紫外光谱分析.     

三联吡啶化合物的溶剂致荧光变色及丁醇异构体鉴别

在三联吡啶分子中引入N,N-二甲基官能团, 实现了三联吡啶分子的局部激发态发光. 研究发现, 溶剂的极性诱导三联吡啶的偶极矩发生变化, 实现了从深蓝光(λ_max=384 nm)到黄光(λ_max=558 nm)的溶剂致荧光变色. 由于三联吡啶的荧光易受醇溶剂中—OH基团振荡猝灭, 不同空间位阻的正丁醇、 异丁醇、 仲丁醇及叔丁醇溶剂使得三联吡啶发光光色相近, 但发光强度的差异较大. 三联吡啶进一步与ZnCl₂配位得到了三联吡啶-Zn(Ⅱ)配合物, 金属离子Zn(Ⅱ)的配位作用促进了三联吡啶分子内电荷转移. 由于电子给体N,N-二甲基官能团可发生平面扭曲, 丁醇异构体可调节三联吡啶-Zn(Ⅱ)的局部激发态和扭曲分子内电荷转移发光, 进而实现其在丁醇异构体溶剂中发光光色的调节. 因此, 三联吡啶和三联吡啶-Zn(Ⅱ)具有良好的溶剂致荧光变色性能, 可应用于4种丁醇异构体的鉴别.     

SAPO-18/SAPO-34共晶分子筛的合成及表征

以三乙胺(TEA)和N,N-二异丙基乙胺(DIEA)为双模板剂经恒温水热晶化法合成了SAPO-18(AEI结构)与SAPO-34(CHA结构)两相共生的SAPO分子筛. 考察了DIEA用量、 硅铝比及晶化时间等因素的影响, 并通过X射线衍射(XRD)、 扫描电子显微镜(SEM)和氨气程序升温脱附(NH₃-TPD)等手段对所得样品的晶相、 形貌和酸性进行了表征. 结果表明, 当n(DIEA)/n(Al₂O₃)=0.2, n(SiO₂)/n(Al₂O₃)=0.6, 晶化时间为4 d时, 得到形貌规整, 结晶度高且AEI/CHA结构比为74:26的共生相SAPO分子筛. 随着晶化时间的延长, SAPO-18在AEI/CHA共生相中所占比例逐渐上升, 表明SAPO-5, SAPO-34和SAPO-18三者中SAPO-18的热力学稳定性最高. 二甲醚制烯烃(DTO)催化性能测试结果表明, AEI/CHA共晶结构比为74/26的共生相分子筛具有较高的催化活性和双烯(C₂⁼+C₃⁼)选择性(84.29%), 同时积碳生成速率较慢.     

Determination of twelve heparin- and heparan sulfate-derived disaccharides as 2-aminoacridone derivatives by capillary zone electrophoresis using ultraviolet and laser-induced fluorescence detection

In quest for high sensitivities, we developed an ultrahigh capillary electrophoresis (CE) method for the structural analysis of heparin and heparan sulfate (HS) in biologic samples. Heparin and HS were digested with an equi-unit mixture of heparin lyases I, II and III and the obtained Delta-disaccharides were derivatized with the fluorophore 2-aminoacridone. All known twelve non-, mono-, di- and trisulfated Delta-disaccharides were completely resolved in a single run, using 50 mM phosphate buffer, pH 3.5, and reversed polarity at 30 kV. Relative standard deviation in migration times and peak areas as well as day-to-day variance ranged from 0.9 to 2.4%, suggesting a reproducible and precise method. Detection of 2-aminoacridone (AMAC)-derivatives of Delta-disaccharides by UV at 255 nm showed 2.8 and 10 times higher sensitivity than that of derivatized and non-derivatized ones at 232 nm. Laser-induced fluorescence detection with an Ar-ion laser source showed an approximately 100 times higher sensitivity than that obtained at 232 nm of the non-derivatized species. Application of this method to quantitative analysis of Delta-disaccharides derived from porcine intestinal mucosa heparin and bovine kidney HS showed excellent agreement with previously published methods, suggesting an accurate method. The developed method can be easily applied for the disaccharide analysis of heparin/HS at the attomole level with high accuracy, for distinguishing between heparin and HS and may be of value for studying their interactions with matrix effective molecules.     

Rapid and sensitive analysis of disaccharide composition in heparin and heparan sulfate by reversed-phase ion-pair chromatography on a 2 μm porous silica gel column

A rapid and sensitive method was developed for the analysis of disaccharide composition in heparin (HP) and heparan sulfate (HS) by reversed-phase ion-pair chromatography on a 2 μm porous silica gel column. HP and HS were digested with heparin lyase I, II and III in combination, and the produced unsaturated disaccharides were separated within 15 min. Calibration graphs were linear in the range 1 ng–1 μg with the fluorometoric post-column detection using 2-cyanoacetamide.     

Expedient Synthesis of Core Disaccharide Building Blocks from Natural Polysaccharides for Heparan Sulfate Oligosaccharide Assembly

The complex sulfation motifs of heparan sulfate glycosaminoglycans (HS GAGs) play critical roles in many important biological processes. However, an understanding of their specific functions has been hampered by an inability to synthesize large numbers of diverse, yet defined, HS structures. Herein, we describe a new approach to access the four core disaccharides required for HS/heparin oligosaccharide assembly from natural polysaccharides. The use of disaccharides rather than monosaccharides as minimal precursors greatly accelerates the synthesis of HS GAGs, providing key disaccharide and tetrasaccharide intermediates in about half the number of steps compared to traditional strategies. Rapid access to such versatile intermediates will enable the generation of comprehensive libraries of sulfated oligosaccharides for unlocking the “sulfation code” and understanding the roles of specific GAG structures in physiology and disease.     

Laser-induced fluorescence as a powerful detection tool for capillary electrophoretic analysis of heparin/heparan sulfate disaccharides

In quest for high sensitivities necessary for determining the disaccharide composition of heparin/heparan sulfate present in trace amounts in biologic samples, an ultrahighly sensitive capillary electrophoresis (CE) method using laser-induced fluorescence (LIF) detection was developed. Heparin/heparan sulfate-derived Delta-disaccharides were derivatized with the fluorophore 2-aminoacridone and resolved by a reversed-polarity CE method. Estimation of the limit of detection in concentration term and limit of quantitation showed that LIF detection of AMAC-derivatives of Delta-disaccharides resulted in 27-744 times higher sensitivity as compared to those detected by UV at 255 nm. These data suggest that CE-LIF is a powerful tool to quantify minute amounts of heparin/heparan sulfate disaccharides.     

Identification of oligomeric domains within dermatan sulfate chains using differential enzymic treatments, derivatization with 2-aminoacridone and capillary electrophoresis

Galactosaminoglycans, i.e. dermatan sulfate (DS) and chondroitin sulfate, are linear heteropolysaccharides consisting of repeating disaccharide units of L-iduronic acid (L-IdoA) or D-glucuronic acid (D-GlcA) residues linked to N-acetyl-galactosamine. High-performance capillary electrophoresis (HPCE or CE) has been successfully used for determining the disaccharide composition of glycosaminoglycans. However, only limited information is available on how to identify oligomeric domains rich in D-GlcA or L-IdoA. The aim of this study was therefore to develop a rapid and accurate CE procedure by which such oligosaccharides can be determined together with the variously sulfated disaccharides. Isolated dermatan sulfates of human origin were separately digested with chondroitinases ABC, AC and B and the enzymic products were derivatized with 2-aminoacridone. CE analysis of these products was performed using a phosphate buffer, pH 3.0, and reversed polarity at 30 kV. The derivatization enabled their detection with laser-induced fluorescence (LIF) and UV at 260 nm at much higher sensitivity than the detection of nonderivatized delta-saccharides at 232 nm and therefore components undetectable at 232 nm were nicely detected after derivatization. Except for delta-disaccharides, altogether five distinct oligosaccharides with differences in charge density were identified. Depending on the lyase that produced these oligomers, information on the presence of L-IdoA- or D-GlcA-containing domains within the DS chain and the sulfation pattern of these oligomeric domains was obtained. This CE method could also be useful in studying the functional oligomeric domains in galactosaminoglycan chains.     

原位限域生长策略制备有序介孔碳负载的超小MoO3纳米颗粒

采用原位限域生长策略制备了一系列有序介孔碳负载的超小MoO₃纳米颗粒复合物(OMC-US-MoO₃). 其中, 有序介孔碳被用作基质来原位限域MoO₃纳米晶的生长. 依此方法制备的MoO₃纳米晶具有超小的晶粒尺寸(<5 nm), 并在介孔碳骨架内具有良好的分散度. 制得的OMC-US-MoO₃复合物具有可调的比表面积(428~796 m²/g)、 孔容(0.27~0.62 cm³/g)、 MoO₃质量分数(4%~27%)和孔径(4.6~5.7 nm). 当MoO₃纳米晶的质量分数为7%时, 所得样品OMC-US-MoO₃-7具有最大的孔径、 最小的孔壁厚度和最规整的介观结构. 该样品作为催化剂时, 表现出优异的环辛烯选择性氧化性能.     

Synthesis of Ruthenium-Graphene Quantum Dots Artificial Oxidase and Its Application in Colorimetric Detection of Phoxim in Carrots北大核心CSCD

The histidine functionalized graphene quantum dots（His-GQDs）react with ruthenium trichloride to form a stable ruthenium complex. This complex is treated in a N2 atmosphere at 600 ℃ for 1 h to obtain a ruthenium-graphene quantum dot composite （Ru-His-GQD）. The results of scanning electron microscopy （SEM）and transmission electron microscopy（TEM）analysis demonstrate that Ru-His-GOD has one three-dimensional structure. The diameter of ruthenium nanoparticles is between 40 and 60 nm. Ru-His-GQD is rich in functional groups and has high oxidase-like activity. Based on Ru-His-GQD catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine（TMB）to produce blue compounds,a photometric method for the determination of phoxim in carrots is established. Phoxim can inhibit the activity of Ru-His-GQD oxidase,resulting in a decrease in the absorbance of the blue compound. When the concentration of phoxim is between 30～240 μg/ L,the absorbance of the oxidation product of TMB at 652 nm decreases linearly with the increase of phoxim concentration. The detection limit of the method reaches 7. 33 μg/L（S/N=3）,and the sensitivity is higher than those in literature. It has been successfully applied to the detection of phoxim in carrots. © 2022, Science Press (China). All rights reserved.     

Insights into the mechanism of separation of heparin and heparan sulfate disaccharides by reverse-phase ion-pair chromatography

Reverse-phase ion-pair high performance liquid chromatography (RPIP-HPLC) and ultra-performance liquid chromatography (RPIP-UPLC) are increasingly popular chromatographic techniques for the separation of organic compounds. However, the fine details of the RPIP separation mechanism are still being debated. Many factors including type and concentration of the ion-pairing reagent, mobile phase pH, organic modifier, ionic strength, and stationary phase all play a role in the overall efficiency and optimization of ion-pairing separations. This study investigates the role that competition between ion-pairing reagents with different steric bulk and hydrophobicity plays in the separation of structural isomers of heparin and heparan sulfate (HS) disaccharides. In addition to providing insights into the mechanism by which RPIP-HPLC can resolve closely related disaccharides, the use of competition between ion-pairing agents could lead to new methods for the separation of larger heparin and HS oligosaccharides. This approach should also be applicable to the analysis of other compound classes, and could lead to a general approach for the chromatographic resolution of mixtures of charged analytes having similar structures.     

Capillary electrophoresis of complex natural polysaccharides

Complex natural polysaccharides, glycosaminoglycans (GAGs), are a class of ubiquitous macromolecules that exhibit a wide range of biological functions and participate and regulate multiple cellular events and (patho)physiological processes. They are generally present either as free chains (hyaluronic acid and bacterial acidic polysaccharides) or as side chains of proteoglycans (PGs; chondroitin/dermatan sulfate, heparin/heparan sulfate, and keratan sulfate) and are most often found in cell membranes and in the extracellular matrix. The recent emergence of modern analytical tools for their study has produced a virtual explosion in the field of glycomics. CE, due to its high resolving power and sensitivity, has been useful in the analysis of intact GAGs and GAG-derived oligosaccharides and disaccharides affording concentration and structural characterization data essential for understanding the biological functions of GAGs. In this review, novel off-line and on-line CE-MS and MS/MS methods for screening of GAG-derived oligosaccharides and disaccharides will be discussed.     

光源的选择对水溶性磺酸卟啉光催化对萘二酚类物质催化性能的影响

制备了水溶性磺酸卟啉(TPPS, TMPPS)及其铁配合物(FeTPPS). 以过氧化氢为氧源、 碘钨灯为光源, 水溶性磺酸卟啉可以高效光催化氧化1,5-萘二酚, 产物为5-羟基-1,4-萘二醌. 测定了卟啉的荧光量子产率及寿命, 分析了催化机理. 选择波长在350~650 nm区间内6个波段和功率在0~20 W区间内4种功率的光源, 探索了不同波段及功率的光源对卟啉光催化活性的影响. 研究结果表明, 不同波段的光源对卟啉光催化1,5-萘二酚的催化活性顺序为λ_380—385>λ_360—370>λ_580—585>λ_620—630>λ_492—577>λ_450—470, 该活性顺序与卟啉的紫外-可见吸收密切相关; 当使用相同波段光源时, 卟啉配体催化氧化1,5-萘二酚的反应速率常数与功率呈良好的线性关系; 卟啉铁配合物随着光源功率的增大, 其催化活性与光解程度有直接关系.