关于求解常微方程组的离散波形松驰方法的加速收敛

提出一种关于求解常微线性系统的离散波形松驰方法的新的加速收敛技巧。通过对系统矩阵A的分裂，该技巧使迭代矩阵（(zI M)^-1N）具有理想的较小谱半径。在LU分解的基础上给出了一个迭代算法以及用该法与Gauss-Seidel方不垢敛速进行比较的数值例子。     

Fluorometric determination of sugars using fluorescein-labeled concanavalin A–glycogen conjugates

The fluorescence of fluoresceinisothiocyanate-labeled concanavalin A (FITC-Con A) was quenched by forming an FITC-Con A–glycogen conjugate and dequenched upon addition of sugars to the conjugate solution due to disaggregation of the conjugate. However, fluorescence quenching was barely observed upon formation of FITC-Con A–dextran conjugate. The sugar-induced fluorescence response of the FITC-Con A–glycogen conjugate depended significantly on the type of sugar: methylated α-D-glucose and α-D-mannose both induced high and rapid responses, while the responses to D-mannose and D-glucose were moderate. In contrast, no response was observed in the presence of D-galactose due to a lack of affinity to Con A. Thus, it is apparent that D-glucose and other sugars can be detected via the fluorescence of the FITC-Con A–glycogen conjugate.      

Composite cryogel with immobilized concanavalin A for affinity chromatography of glycoproteins

Composite cryogels containing porous adsorbent particles were prepared under cryogelation conditions. The composites with immobilized concanavalin A (Con A) were used for capturing glycoproteins. Adsorbent particles were introduced into the structure in order to improve the capacity and to facilitate the handling of the particles. The monolithic composite cryogels were produced from suspensions of polyvinyl alcohol particles and porous adsorbent particles and cross‐linked under acidic conditions at sub‐zero temperature. The cryogels were epoxy activated and Con A was immobilized as an affinity ligand. Binding and elution of horseradish peroxidase (HRP) was studied in batch experiment and in a chromatographic setup. Increasing adsorbent concentration in composite cryogels will increase ligand density, which therefore enhances the amount of bound HRP from 0.98 till 2.9 (milligram enzyme per milliliter of gel) in the chromatographic system. The material was evaluated in 10 cycles for binding and elution of HRP.     

Electrochemical Determination of Carbofuran in Tomatoes by a Concanavalin A (Con A) Polydopamine (PDA)-Reduced Graphene Oxide (RGO)-Gold Nanoparticle (GNP) Glassy Carbon Electrode (GCE) with Immobilized Acetylcholinesterase (AChE)

A new biosensor method was developed to determine residual carbofuran in tomatoes in a rapid and convenient fashion based on immobilizing acetylcholinesterase (AChE) on an electrode modified by concanavalin A (Con A)/polydopamine (PDA)-reduced graphene oxide (RGO)-gold nanoparticle (GNP) nanocomposites. The specific binding between Con A and AChE was investigated by the Ellman method and cyclic voltammetry (CV). The synthesis of nanocomposites was monitored by ultraviolet-visible absorption spectroscopy, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The results showed that, due to the specific binding and good electrical conductivity, the biosensor had 2.2 times higher bioactivity, leading to high sensitivity with a low Michaelis constant of 0.10?mM. Parameters that affect the response of the biosensor, such as the pH, enzyme loading, ionic concentration, and inhibition time, were optimized. When used for the detection of carbofuran, this biosensor showed a wide range of applicability from 5?µg/kg to 40?µg/kg with a detection limit of 0.012?µg/kg. In addition, the biosensor demonstrated good recovery values of 101% and 90% for 10?µg/kg and 100?µg/kg of the analyte, good stability, high repeatability, and a rapid detection time of 20?min for carbofuran in tomatoes, which provides significant advantages for future analysis.     

Preparation of an Organized Film Composed of Polymers,Avidin, and Concanavalin A and Its Binding Properties

The multilayer thin films composed of polymers, avidin, and concanavalin A (Con A) were prepared on the surface of a quartz slide by alternate deposition of anionic and cationic polymers and the proteins. The loading of avidin and Con A in the film was evaluated spectroscopically by using Texas Red tagged avidin and Con A. Avidin molecules assembled in the film caused its binding activity toward biotin and analogue 2-(4′-hydroxyphenylazo)benzoic acid to be retained. The polymer layers contributed to improving stability of the protein film.

Polymer/Con A/avidin composite film on a solid surface.     

Radioimmunoassay of progesterone and estriol in plasma using antibodies immobilized onto protein A-sepharose CL-4B

Protein A-Sepharose CL-4B was used as a solid phase for antibodies in the radioimmunoassay of progesterone and estriol. The method was fast and easily standardizable. Immobilized antibodies had the same binding capacity as free antibodies and gave good correlation curves (r = 0.996 for progesterone andr = 0.989 for estriol). Sensitivity was 12.5 pg/tube for progesterone and 8.0 pg/tube for estriol. Comparison of progesterone radioimmunoassay with chemically immobilized antibody onto Sepharose CL-4B was also carried out.     

糖蛋白-凝集素自组装构筑有序膜及在酶电极的应用

利用糖蛋白-凝集素的识别作用交替沉积伴刀豆球蛋白（Con A）与辣根过氧化物酶(HRP)制备酶自组装多层膜，用原子力显微镜（AFM）观测了自组装膜的表面形貌、表面粗糙度； AFM和椭圆偏振研究测定了自组装膜的厚度.结果表明, Con A和HRP膜厚分别为9.0和4.6 nm，与两者的晶体衍射结果一致，说明生物识别自组装方法能很好地保持分子的原有形态.以亚甲蓝（MB）溶液为介体，用循环伏安法测定了表面修饰了三层（Con A/HRP）自组装膜的金电极对H2O2的电化学催化还原作用，在H2O2浓度为0.2～1.0 mmol•L－1时，响应电流对H2O2浓度变化成线性，酶电极灵敏度为24.0 mA•mol－1•L，表观米氏常数为4.2 mmol•L－1.     

Effect of Sodium Dodecyl Sulfate on Concanavalin A-Sepharose During Affinity Chromatography of High-Affinity Binding Toxin Protein Of Bacillus thuringiensis subsp. kurstaki

Abstract

Concanavalin A- Sepharose affinity chromatography is a powerful tool for isolation or purification of peripheral or integral membrane proteins or other glycoproteins. The insecticidal crystal toxin from Bacillus thuringiensis subsp. kurstaki is a glycoprotein containing “high-mannose” or “hybrid”-type sugar chains. The protein has a high binding affinity for concanavalin A lectin and could not be eluted even with 0.5M methyl α-D-mannopyranoside. Nonspecific elution with 0.03% SDS coeluted the matrix con A with bound protein. Experimental results indicated that con A leaching is mainly because of inclusion of detergents in buffer systems and may not be directly related to the nature of the sample protein.

² Abbreviations used: Con A: concanavalin A, SDS: sodium dodecyl sulfate, SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis, MeG: methyl α-D-glucopyranoside, MeM: methyl α-D-mannopyranoside     

糖蛋白印迹二维光子晶体水凝胶传感器的构建

制备了一种特异性识别糖蛋白的二维光子晶体分子印迹水凝胶。以刀豆蛋白A(Con A)为模板分子,甲叉双丙烯酰胺(MBA)为交联剂,丙烯酰胺(AAm)与4-乙烯基苯硼酸为功能单体,N,N,N′,N′-四甲基乙二胺(TEMED)为引发剂,过硫酸铵(APS)为催化剂,在聚苯乙烯二维光子晶体(PC)表面产生聚合反应形成水凝胶,接着用10%的乙酸溶液洗脱模板分子,制备了可对Con A特异性识别的二维光子晶体分子印迹水凝胶(MIPs)传感器。结果表明,当MIPs的交联度为10%时,德拜环的直径变化最显著,对目标物的识别最灵敏。该传感器对Con A在0~0.5 mg/mL范围内具有良好的响应与识别能力,可用于目标物的富集和即时检测。同时,苯硼酸的引入,增加了印迹空穴的识别位点,进一步改善了印迹材料对糖类分子的特异识别性。该水凝胶传感器在卵清白蛋白(OVA)、牛血红蛋白(BHb)、溶菌酶(Lyz)、胰蛋白酶(Try)溶液中德拜环的直径变化远小于识别相同浓度的Con A引起的德拜环直径的变化,表现出良好的选择性。该方法操作简单,成本低廉,可重复使用,不需特殊仪器设备,可拓展到其它糖蛋白,实现糖类目标蛋白的即时快速检测。     

血清白蛋白的构象研究Ⅳ．pH诱导HSA构象变化的光谱研究

用紫外吸收二阶导数谱辅以荧光光谱、紫外吸收光谱研究了ｐＨ＝３．０～１１．０范围内ＨＳＡ中芳香氨基酸残基微环境的变化，以此作为推断构象变化的探针。