蓖麻毒蛋白的研究与应用

蓖麻毒蛋白（Ricin）是一种核糖体失活蛋白,由A、B两个肽链以二硫键共价相连接,其A链在B链的协助下,容易穿过细胞膜,破坏核蛋白体60S亚单位,抑制蛋白质的合成,导致细胞死亡。Ricin几乎对所有真核细胞具有很强的毒害作用,被认为是一种新型的很有希望的抗癌药物以及具有极大潜力的生物农药。Ricin能抑制昆虫的蛋白质合成,而植物自身能免受毒害,因此利用Ricin开发生物农药具有广阔前景。文章筒述了Ricin的分离纯化方法、结构及性质,毒性作用机理,及其在医学,生物农药,军事等方面的应用。     

有机磷杀菌剂(二)

有机磷杀菌剂的主要品种有稻瘟净、异稻瘟净、克瘟散等。它们结构相似,生物活性谱大致相同,彼此之间存在交互抗性,可以推断作用方式是一样的。实验指出:这类化合物抑制细胞壁的合成和细胞膜的渗透性。稻瘟病菌Pyricularia oryzae对稻瘟净很敏感。在50ppm浓度下药剂不影响菌丝体呼吸,蛋白质及核糖核酸的合成。但是,~(14)C-氨基葡     

Na2SO3对SPI体系挤出加工的影响

作为生物降解材料之一的蛋白质,分子化学结构之中,除肽键外,蛋白质分子间和分子内还有很强的氢键、偶极作用、离子键、疏水相互作用及二硫共价键,所以蛋白质具有刚硬、脆性的物理特性和较差的流动性。蛋白质体系中加入和不加入亚硫酸钠在挤出现象上差别很大,可能是由于二硫共价键的存在使其不易挤出,而还原剂的亚硫酸钠能够破坏二硫键,HAAKE和FT-IR红外分光光度计的研究可以发现亚硫酸钠起到破坏二硫键的作用。     

早孕因子的研究进展

早孕因子(Early pregnancy factor,EPF)是一种具有免疫抑制和生长因子特性的分泌性蛋白质,在受精后的孕血清及某些恶性肿瘤患者血清中均能检测到。EPF与伴侣素10(Chaperonin 10,Cpn10)是同源的。EPF首先通过玫瑰花结抑制试验在哺乳动物的孕血清中被发现。EPF单克隆抗体在妊娠诊断、肿瘤诊断和治疗等方面均有广阔的应用潜力。本文就EPF的来源、化学结构和生化特性、分离纯化及检测、作用及应用等研究进展作一综述。     

基于蛋白及其组装体的金属纳米复合材料构建

将蛋白分子及其自组装体作为模板用于功能性金属纳米材料合成吸引了研究者的广泛关注。蛋白质及其自组装体形态结构独特多样,具有特异性分子识别及仿生矿化能力,在纳米材料形成过程中可发挥结构导向及形貌控制作用,以其为模板构建的蛋白-金属纳米复合材料在催化转化、生物传感、医学成像等领域具有广阔的应用前景。本文基于蛋白质及其组装体的结构特征差异,综述了近些年在以蛋白质单亚基结构、蛋白多亚基超组装结构及蛋白三维晶体结构为模板的金属纳米复合材料构建研究方面取得的进展,并对其未来的研究发展方向进行了展望。     

基于蛋白及其组装体的金属纳米复合材料构建

将蛋白分子及其自组装体作为模板用于功能性金属纳米材料合成吸引了研究者的广泛关注。蛋白质及其自组装体形态结构独特多样,具有特异性分子识别及仿生矿化能力,在纳米材料形成过程中可发挥结构导向及形貌控制作用,以其为模板构建的蛋白-金属纳米复合材料在催化转化、生物传感、医学成像等领域具有广阔的应用前景。本文基于蛋白质及其组装体的结构特征差异,综述了近些年在以蛋白质单亚基结构、蛋白多亚基超组装结构及蛋白三维晶体结构为模板的金属纳米复合材料构建研究方面取得的进展,并对其未来的研究发展方向进行了展望。     

转谷氨酰胺酶促壳聚糖/壳聚糖衍生物对蛋白质糖基化 作用的研究进展

转谷氨酰胺酶途径糖基化具有效率高、特异性高、安全性高等优点被广泛地应用于蛋白质改性。为了研究采用转谷氨酰胺酶途径进行蛋白质糖基化对蛋白质功能性质、结构的影响,本文对国内外该途径糖基化的研究现状进行综述。首先介绍了糖基化选用的代表性多糖——壳聚糖及其衍生物,以及转谷氨酰胺酶催化蛋白质与多糖交联的机理。然后,重点阐述了酶法糖基化对蛋白质表面疏水性、溶解性、乳化性等加工性能的影响,以及对蛋白质结构变化的影响,包括一级结构、二级结构、微结构。其次,对目前该法修饰蛋白质在可食膜、医用敷料、抑制晚期糖基化终末产物方面的应用做了简要介绍,充分显示其在各领域的应用价值。最后展望了转谷氨酰胺酶途径蛋白质糖基化的未来研究方向和亟待解决的问题。     

蛋白质相互作用抑制剂生物活性测定方法综述

许多疑难杂症,如癌症、艾滋病、老年痴呆症、帕金森综合症等的出现和跟蛋白质-蛋白质之间的相互作用有着密切联系。蛋白质相互作用抑制剂,通过抑制蛋白质表面的蛋白质-蛋白质相互作用,阻断某些病毒与受体的结合,从而起到治疗疾病的作用。综述了几种测定蛋白质相互作用抑制剂生物活性的方法。     

核糖核酸的应用与制备

核糖核酸除了在基因的表达和蛋白质的生物合成方面起着关键的作用外 ,还具有改善机体多种生理功能的作用。核糖核酸的结构与功能及应用的研究一直是生物科学的重点领域之一。概述了核糖核酸的制备状况及其在临床、医药、保健、食品加工业、农业生产等领域的应用。     

基于自由能的生物大分子结构研究

生物大分子结构研究是生物学的一个重要内容,基于自由能的生物大分子结构研究在理论和应用上都具有重要意义。综述了自由能这个经典判据在划分蛋白质结构域、预测RNA二级结构及蛋白质工程等中的应用。     

Purification of ice structuring protein complexes from winter wheat using Triton X-114 phase partitioning

Ice structuring proteins (ISPs) isolated from the cold-acclimated plants have a great potential in improving the quality of frozen foods. The purification of ISP complexes from winter wheat was achieved using an aqueous two-phase system of Triton X-114. The highly reactive phenols were removed, and the ISP complexes remained in the aqueous phase after phase separation. The ISP complexes treated by this procedure retained higher thermal hysteresis activity than those treated by ammonium sulfate method. The phase separation technique provides a simple and mild way for removing phenols from ISP complexes.     

Purification of ice structuring protein complexes from winter wheat using Triton X-114 phase partitioning

Ice structuring proteins (ISPs) isolated from the cold-acclimated plants have a great potential in improving the quality of frozen foods. The purification of ISP complexes from winter wheat was achieved using an aqueous two-phase system of Triton X-114. The highly reactive phenols were removed, and the ISP complexes remained in the aqueous phase after phase separation. The ISP complexes treated by this procedure retained higher thermal hysteresis activity than those treated by ammonium sulfate method. The phase separation technique provides a simple and mild way for removing phenols from ISP complexes.     

Population balance and computational fluid dynamics modelling of ice crystallisation in a scraped surface freezer

Ice crystallisation in a scraped surface freezer is exceedingly complex and there is very limited fundamental understanding of the influences of fluid flow and heat transfer on ice crystal size, number and shape. This paper presents a computer modelling study that combines population balance method and computational fluid dynamics method. Ice crystal nucleation and growth kinetics has been described by discrete population balance equation. Algorithms for solving the coupled equations of fluid flow, heat transfer and discrete population balance of ice crystallisation have been developed and implemented into a commercial code. Demonstrated is a 2-D computer simulation of ice crystallisation in a scraped surface freezer. Although the simulation makes several assumptions including simplified fluid flow conditions, the predicted ice crystal size distribution is comparable to the experimental data. It is shown that with combined computational fluid dynamics and population balance modelling much insight into the interaction of fluid flow, heat transfer and ice crystallisation in the scraped surface freezer can be obtained.     

Evaluating the Oil‐Gelling Properties of Natural Waxes in Rice Bran Oil: Rheological,Thermal, and Microstructural Study

The main objective of this research was to enhance the understanding of the oil‐structuring properties of natural waxes. A number of natural food‐grade waxes were evaluated for their oil‐gelling properties using a combination of techniques, including rheology, differential scanning calorimetry, and polarized light microscopy. Based on the rheological measurements (oscillatory, flow, and thixotropic behavior), we found that rice bran wax, carnauba Brazilian wax and fruit wax showed weak gelling behavior in rice bran oil (prepared at concentrations as high as 5 % w/w), exhibiting relative low elastic moduli that displayed a high frequency dependency. On the contrary, carnauba wild wax, berry wax, candelilla wax, beeswax, and sunflower wax were efficient oleogelators forming strong gels at concentration of <2 % w/w. We attempt to explain these observed differences in gelling behavior by crystal morphology, network formation, and the final amount of crystalline phase.     

Morphology of an asymmetric ethyleneoxide-butadiene di-block copolymer in bulk and thin films

We present experiments on the melt and crystal morphology of a asymmetric semi-crystalline poly(ethylene/butylene-b-ethyleneoxide) diblock copolymer (PB_h-b-PEO) in bulk as well as in thin films. Simultaneous small- and wide-angle X-ray scattering combined with AFM and TEM images reveal in the melt a bulk morphology of hexagonally packed cylinders of PEO in a PB_h matrix, that transforms into a hexagonal perforated lamellar phase upon crystallization. X-ray reflectivity of thin films of PB_h-b-PEO in the melt indicates wetting layers at the top and bottom interfaces, which force the cylinders in the interior to orient parallel to the substrate. Crystallization of the PEO block leads to roughening of the air/film interface and causes lateral structuring coexisting with planar lamellar layers in thinner films.     

不同形貌ZSM-5分子筛合成及烯烃裂解反应性能

在ZSM-5分子筛制备过程中,通过控制成核过程中的动力学过程、晶体生长过程和转化活能,可以调节晶体的形貌和尺寸。本文调节体系合成条件,包括成核时间、投料比例、投料类型和晶化温度等因素探讨了分子筛形貌变化。同时对不同分子筛材料进行XRD、SEM、N_2物理吸附-脱附等表征,探究合成动力学对分子筛形貌和特性的影响。结果发现,(1)延长老化时间将导致分子筛的均匀分散;(2)只有适当的初始凝胶溶液的碱度可以得到典型分子筛晶体;(3)反应温度及硅源类型显著影响晶体生长,影响粒子的大小和形态;(4)不同尺寸晶体在碳四烯烃催化裂解制丙烯反应中催化性能不同,其中小颗粒分子筛具有更好的催化裂解活性及活性稳定性。     

添加剂对HMX重结晶晶体形貌的影响

通过模拟计算与试验相结合的方法,研究了添加剂乙酰胺、丙烯酰胺、乙胺水溶液对重结晶HMX晶体形貌控制的影响.结果表明,3种添加剂对HMX重结晶晶体形貌影响的大小顺序为:乙酰胺＞丙烯酰胺＞乙胺,乙酰胺使晶体偏离球形化,丙烯酰胺具有使晶体向着球形化发展的趋势,由于乙胺与HMX晶面的附着能较小,乙胺对HMX重结晶晶体形貌改变不...     

Ice-mould freeze casting of porous ceramic components

Porous, hollow ceramic components were produced by freeze casting technique. For this purpose aqueous slurries with high solid contents were prepared which were stable against freezing down to at least −5 °C. Ice cores were made by coating steel components with freezing water which were subsequently dip-coated with the ceramic suspensions. After freeze drying which removes both, the ice core and the frozen suspension liquid, and sintering, ceramic components with a high amount of open porosity including steel parts could be achieved. As an example hydroxyapatite was used for showing the opportunities of the freeze casting technology among others for applications in the field of bone replacement. The influence of the solid content of the hydroxyapatite slurries on the ice crystal growth has been investigated by means of compact hydroxyapatite bodies which were prepared by freeze casting using ice moulds with cylindrical cavities.     

超声处理对羟基磷灰石纳米针状晶形成的影响

实验采用液相沉淀法以硝酸钙和磷酸氢二铵为原料，以水为溶剂，以氨水为调节剂。采用不同的工艺条件(反应物浓度和分散剂种类)制备了羟基磷灰石，然后对试样进行超声处理。研究了制备工艺条件对所获纳米针状晶体在形态和生长上影响。     

添加剂作用下阿司匹林结晶模拟和实验研究

晶体形貌作为晶体产品的重要质量指标,不仅会影响产品流动性、稳定性、溶出速率和生物可利用度等产品的质量指标,还会对过滤、干燥、压片等下游操作造成影响。通过分子模拟的方法指导阿司匹林冷却-反溶剂结晶过程的添加剂筛选,以添加剂作为晶体形貌的改性剂,降低阿司匹林晶体的长径比优化晶体形貌。通过单因素实验考查了添加剂浓度、晶种加入量、降温速率、搅拌速率和加水速率对阿司匹林晶体产品形貌、流动性和粒度分布等的影响,确定了较优的工艺条件。实验结果表明加入聚乙烯吡咯烷酮（PVP）作为添加剂可以降低阿司匹林晶体长径比,获得形貌为短棱柱状的晶体产品,能够显著改变晶体形貌优化产品的流动性。