草浆造纸黑液中胶体成分的测定方法及其对黑液碱回收的影响

根据草浆造纸黑液组成的特殊性，研究了草浆黑液中液体成分的测定方法，进行了样品分析和回收率试验．取得了较满意的结果。在些基础上讨论了草浆黑液中胶体成分对于黑液碱回收过程的影响。     

High Performance Liquid Chromatography and Proteolytic Enzyme Characterization of Peptides in Tooth Pulp Extracts

Abstract

Metabolic profiles are obtained for peptides contained in tooth pulp extracts. To determine which high performance liquid chromatographic peaks are due to peptides, a series of proteolytic enzymes (chymotrypsin, trypsin, and carboxypeptidase A) are utilized. Results from treatment of extracts with immobilized enzymes demonstrate that virtually all peaks in this reverse phase system are due to peptides. This current study is a necessary component in a larger research program focusing on quantification of enkephalin-and endorphin-related peptides in biologic extracts including brain and tooth pulp tissue.     

Reduction of Enzyme Dosage by Oxygen Delignification and Mechanical Refining for Enzymatic Hydrolysis of Green Liquor-Pretreated Hardwood

In this study, a strategy to reduce enzyme dosage is evaluated by applying two post-treatments, oxygen delignification and mechanical refining. The sugar conversion for GL12 substrates was increased from 51.5% to 77.9% with post-treatments at the enzyme dosage of 10 FPU. When the amount of enzyme was reduced to 5 FPU with post-treatments, the conversion of 71.8% was obtained, which was significant higher than the conversion without any post-treatment using 10 FPU (51.5%). This clearly demonstrates the benefit of post-treatments that allows more than 50% of enzyme reduction at the same level of enzymatic conversion. Enzyme-accessible surface area and pore volume were evaluated by Simons' staining and DSC thermoporometry methods, and strong correlations were found with the sugar conversion.     

The Application of the Starfish Hatching Enzyme for the Improvement of Scar and Keloid Based on the Fibroblast-Populated Collagen Lattice

Various bioactivities of the starfish hatching enzyme (HE) including collagen gel contraction, MMPs activity, hydroxyproline release, and gene regulation based on the fibroblast-populated collagen lattice (FPCL) in three-dimensional medium were investigated for the improvement of scar and keloid. The starfish HE significantly inhibited the collagen gel contraction over 2 days of culture. MMP-2 and MMP-9 activities were also identified by gelatin zymography and RT-PCR products with both HE and collagenase treatments, which resulted in the high amount of hydroxyproline release. The HE treatment on the FPCL significantly inhibited the fibroblast proliferation at 3 days of culture. The LPS-induced NO level and iNOS mRNA expression at low concentrations of HE presented a certain ability to inflammatory response. The COX-2 mRNA from the FPCL indicated no significant inflammation-mediated activity at 5 μg/mL of HE, whereas the cytokines of TNF-α and IL-1β were significantly higher than those of the control. Hence, the starfish hatching enzyme can regulate the fibroblast-populated collagen gel conditions by the contraction, MMP production, inflammatory gene expression, etc. Therefore, the starfish HE could be a potential cosmeceutical to heal the scar and keloid tissue.     

过氧化物模拟酶在介体型生物传感器方面应用初探

meso-四(4-磺基苯)卟啉锰(Ⅲ)作为过氧化物模拟酶可催化H_2O_2与K_4Fe(CN)_6反应。电流响应与H_2O_2浓度在3.0×10~(-4)～1.0×10~(-3)mol/L范围内呈线性关系。重现性和回收率良好。抗坏血酸和DL-半胱氨酸干扰严重。     

酶的改造及其催化工程应用

酶作为生物催化剂在食品、饲料、化妆品以及医药等诸多领域逐渐发挥重要作用。但是,酶对外界环境如pH和温度等很敏感,而实际的反应条件和生物体的生理环境差异较大,因此酶在实际应用中不稳定、容易失活,催化效率下降。酶的这一特点大大限制了其工业化应用。目前,定向进化、糖基化以及化学修饰等方法被广泛用于酶分子的改造以提高其稳定性、催化效率以及扩大其底物范围。其中,定向进化通过模拟自然进化机制,在体外改造基因从而获得性能优化的酶突变体,已经成为了酶改造的重要技术。在酶的实际应用过程中,介质工程、固定化以及多酶催化体系构建等技术被广泛用于提高酶的催化效率。其中,多酶催化体系由于其底物通道效应可以显著提高级联酶反应的效率而备受关注。本文首先重点介绍了近年酶应用的现状,然后从酶定向进化、糖基化以及化学修饰的角度总结了酶改造的方法,最后从介质工程、酶固定化以及体外多酶催化体系等方面进一步总结了酶实际应用中的催化工程策略。     

Application of Amperometric Enzyme Biosensors for Wine and Must Analysis

The work presents application of amperometric biosensors based on platinum printed electrodes and immobilized enzymes alcohol oxidase, glucose oxidase and lactate oxidase for wine analysis. Created devices demonstrate wide dynamic range of work, good stability and high selectivity to the substrate, and are successfully applied for analysis of such complex mixtures as wine and must. Good correlation of the results of analysis of different wines and must obtained by amperometric biosensors and chromatography method is shown. Created biosensors can be used as a basis of commercial device for express analysis of ethanol, glucose and lactate in wine and must during its fermentation.     

Improvement of an Enzyme Immunoassay for the Determination of Mercury(II)

Three systems were tested for the optimization of a heterogenous non-competitive enzyme immunoassay (EIA) for the determination of Hg (II). The sensitivity of the non optimized Hg-EIA with a detection limit of 2.1 μg/L Hg (II) was improved by an avidin-biotin-complex (ABC) amplification system to a 2-fold lower detection limit (1.1 μg/L Hg (II)). A conventional competitive ElA with the competition reaction between bound and free Hg (II) for antibody (ab) binding sites yielded a detection limit of 1.0 μg/L Hg (II). Further improvement of sensitivity could be achieved by a competitive displacement EIA. In this case ab molecules bound to immobilized haptens are displaced in the next step by free Hg (II). The detection limit of the displacement approach is 0.4 μg/L Hg (II).     

Application of a Mixed Adsorbent for Flow TLC

JPC – Journal of Planar Chromatography – Modern TLC -     

Understanding the Nonproductive Enzyme Adsorption and Physicochemical Properties of Residual Lignins in Moso Bamboo Pretreated with Sulfuric Acid and Kraft Pulping

In this work, to elucidate why the acid-pretreated bamboo shows disappointingly low enzymatic digestibility comparing to the alkali-pretreated bamboo, residual lignins in acid-pretreated and kraft pulped bamboo were isolated and analyzed by adsorption isotherm to evaluate their extents of nonproductive enzyme adsorption. Meanwhile, physicochemical properties of the isolated lignins were analyzed and a relationship was established with non-productive adsorption. Results showed that the adsorption affinity and binding strength of cellulase on acid-pretreated bamboo lignin (MWLa) was significantly higher than that on residual lignin in pulped bamboo (MWLp). The maximum adsorption capacity of cellulase on MWLp was 129.49 mg/g lignin, which was lower than that on MWLa (160.25 mg/g lignin). When isolated lignins were added into the Avicel hydrolysis solution, the inhibitory effect on enzymatic hydrolysis efficiency of MWLa was found to be considerably stronger than that with MWLp. The cellulase adsorption on isolated lignins was correlated positively with hydrophobicity, phenolic hydroxyl group, and degree of condensation but negatively with surface charges and aliphatic hydroxyl group. These results suggest that the higher nonproductive cellulase adsorption and physicochemical properties of residual lignin in acid-pretreated bamboo may be responsible for its disappointingly low enzymatic digestibility.     

生物素标识酶在生物传感器中的应用研究

利用生物素与亲合素之间的特异性结合,在恒电位下,首先将亲合素吸附在电极上,然后使标识在生物素上的葡萄糖氧化酶固定于电极表面,制成具有高活性的多层固定化酶的葡萄糖传感器。电极线性范围:1.0×10^-5～1.0×10^-2mol/L,检测限:6.0×10^-6mol/L,响应时间:6s.本传感器具有线性范围宽、灵敏度高、响应速度快、可反复活化使用等优点。     

静电纺丝纳米纤维膜固定化酶及其应用

静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。     

酶催化反应模拟作用的研究及分析应用

生物转是化学和生物学交叉研究领域，包括生物催化剂（酶）工程和反应介质工程两大要素。一方面，开发性能优良的模拟酶，能模拟天然酶生物体内的高催化活性（酶模拟）；另一方面，介质工程可以用体外的方法模拟酶在生物体内细胞膜的微环境（膜模拟），对用体外的方法研究生物内催化信息，探讨生物体系的生命现象具有重要的意义。     

光固化3D打印及其在齿科行业中的应用

光固化3D打印是最早出现的3D打印技术,经过30多年的发展,先后发展出液态树脂固化或光固化（stereolithography,SLA）、数字光处理（digital light processing,DLP）、液晶显示（liquid crystal display,LCD）、连续无分层液体界面提取技术（layerless continuous liquid interface production,CLIP）、双光子3D打印（two-photon polymerization,TPP）、全息3D打印技术等多种打印技术。光固化3D打印技术具有精度高、成型速度快等特点,因此在许多领域都有良好的应用,且前景广阔。在众多领域中,齿科领域个性化特征明显,对打印材料精度要求高,是目前光固化3D打印最有应用潜力和高附加值的领域。本文综述了光固化3D打印技术的种类、原理和技术的优缺点,并简述了光固化3D打印在齿科领域的应用。     

分子印迹技术用于模拟酶及分子反应器的研究进展

分子印迹技术是制备特异性分子识别材料的新技术. 分子印迹聚合物(Molecularly-imprinted polymer, MIP)具有可同酶相媲美的选择性识别能力, 能够催化手性及区域选择性的反应, 是一种新型的分子反应器; 同时MIP具有良好的化学和物理稳定性, 因而在替代酶用于某些苛刻条件下的催化反应方面有良好的应用前景. 就近年来利用MIP模拟酶催化有机合成反应, 以及利用MIP作为分子反应器反面的研究进展进行了综述.     

Evaluation of Enzyme Mixtures in Releasing Fermentable Sugars from Pre-pulping Extracts of Mixed Northeast Hardwoods

One near-term option to developing a forest product biorefinery is to derive pre-pulping extract from incoming wood chips before the main pulping step. The release of monomer sugars from a xylan-rich extract, creating a fermentable substrate is a prerequisite for utilization of pre-pulping extract for production of ethanol or other value-added products. This study examined the individual and mixture efficiencies of two hemicellulolytic microbial enzymes and two xylanase preparations in catalyzing degradation of green liquor (GL) and hot water (HW) pre-pulping extracts. The effects of four commercial enzyme preparations were determined by assessing yields of xylose + galactose + mannose (xmg) obtained under different reaction conditions. Of the individual enzyme preparations tested, a sample NS 50012 was superior to the other enzyme preparations in releasing xmg under conditions optimized for separate hydrolysis and fermentation and for simultaneous saccharification and fermentation. In comparison to pre-pulping extracts treated with HW, extract treated with GL was found to inhibit the action of all tested enzymes. This inhibition may be related to higher salt and lignin phenol in the GL extract. On both types of extracts, the mixture constituted by NS 50012 and NS 50030 provided the highest yield of hemicellulose conversion at 55 °C and pH 5.5. The generated digestibility thus signified that the synergistic effectiveness in xylan + galactan + mannan (XMG) hydrolysis between NS 50012 (from Aspergillus aculeatus) and NS 50030 (from Aspergillus oryzae) is the result of an interaction mechanism involving different XMG-degrading enzyme activities in the two enzyme preparations.     

甲烷氧化菌的高密度培养及其在生物柴油炼制中的应用

天然气是储量最丰富的能源之一,但限于勘探、运输、配置等问题,一直以来人们对它的利用都不是很合理.能源危机和环境问题推动了生物质能源的开发利用,甲烷氧化菌是以甲烷为唯一碳源和能源进行生长的一类细菌,具有炼制生物柴油的潜力.综述了近几年甲烷氧化菌在高密度培养及深加工炼制生物柴油的研究进展,着重分析了高密度培养和生物柴油炼制过程中在传质与反应器设计、菌种培养、脂质提取、加氢脱氧四个过程中面临的技术难点,给出了解决方法并展望了其在未来的发展.     

酶催化反应在立体有机合成中的应用

讨论了水解酶、交换酶以及氧化还原酶催化的位置、对映和潜手性立体专一的反应，包括酶催化的醇或酯的水解反应、酯交换反应、含羰基的化合物及活泼双键的还原反应、ＳＰ￣３杂化的碳及烯的氧化反应（包括Ｂａｙｅｒ－Ｖｉｌｌｉｎｇｅｒ氧化反应）。回顾了酶立体选择性地合成某些重要目标结构的生物催化方法，讨论了酶催化反应的生物合成前景。参考文献１８篇。     

Improvement of Thin-Layer Chromatography for Enzyme Assay of Geranylgeraniol 18-Hydroxylase from Croton stellatopilosus Ohba

JPC – Journal of Planar Chromatography – Modern TLC - Plaunotol, an acyclic diterpenoid present in Croton stellatopilosus Ohba leaves, is a product of hydroxylation, catalyzed by...     

毛细管电泳法在酶抑制剂筛选中的应用

毛细管电泳法以其分离效率高、耗时短、样品用量少、灵敏度高以及易于实现自动化等诸多特点,在筛选酶抑制剂研究中有着不可替代的优势.本文综述了毛细管电泳法在酶抑制剂筛选中的应用.主要介绍了应用最广泛的离线分析(Off-line assay)和在线分析(In-line assay),即柱前酶反应(Pre-capillary enzyme reaction)和在柱酶分析(In-capillary enzyme reaction).并对该领域的未来发展进行了展望.