蜘蛛丝多肽链段结构的优化设计

根据蜘蛛丝氨基酸片段的序列特征,利用 Hyperchem5软件对部分具有β-折叠或螺旋状结构的多肽链段的分子结构进行优化设计,分析了氨基酸种类、聚合度对多肽链段形成特定构象的影响,发现一定的氨基酸片段有形成特定构象的趋势。分子构象的多元化是蜘蛛丝具有优异力学性能的重要原因。     

蜘蛛丝的结晶结构及其取向

研究和分析了大腹园蛛的牵引丝、内层包卵丝的结晶结构及其取向,探索了大腹园蛛丝纤维分子链的排列状态、结晶结构和蜘蛛丝力学性能间的关系。     

成丝的速度与方式和蜘蛛丝力学性能的关系

为了分析蜘蛛丝的力学性能和成丝条件间的关系,研究了不同速度下人工卷取的蜘蛛牵引丝以及蜘蛛垂直下落时分泌的牵引丝的力学性能.研究结果表明,随着卷取速度的增大,蜘蛛丝的断裂强度有一极大值,在高速卷取时强度的变化较低速时平缓.垂直下落时蜘蛛分泌的牵引丝的综合力学性能优异,但断裂强度不一定大于人工卷取的丝.成丝速度和成丝方式都对蜘蛛丝的性能有很大影响.     

大腹园蛛丝腺蛋白二级结构的圆二色性研究

用圆二色光谱研究了大腹园蛛各丝腺蛋白的分子构象、大、小囊状腺体蛋白的分子构象以无规卷曲和β-折替结构为主;而其管状腺、集合状腺、鞭毛状腺蛋白的 CD 谱均显示出有α-螺旋结构的特征。用计算法所得这五种丝腺体蛋白的二级结构中含有6.2%～13.9%不等的β-转角,这对蛛丝蛋白形成独特的结构起着重要作用。还研究了放置时间对这五种丝腺体蛋白构象的影响。     

大腹圆珠牵引丝的结构与性能分析

以大腹圆珠牵引丝为研究对象,分析了蜘蛛丝的聚集态结构特征和形态结构特征。在结构研究的基础上,探索和分析了蜘蛛丝高强度和超收缩性能的形成机理。     

蜘蛛牵引丝蛋白的特性及其分子工程

蜘蛛牵引丝是由蜘蛛主壶腹腺产生的一种具有高度重复结构的蛋白质纤维,它将高抗张强度和高弹性奇妙地结合于一体,是自然界强度最高的纤维.基因解析揭示出牵引丝至少存在两种高度重复的蛋白组分,每种蛋白的重复单元都显示出富丙氨酸区和富甘氨酸区交替的模块结构特征.采用分子工程技术不仅可以生产出具有天然牵引丝蛋白特性的重组蜘蛛丝蛋白,也可为研究牵引丝蛋白的模块结构与功能特性之间的关系开辟道路.文中结合我们的研究综述了牵引丝蛋白的模块结构及其分子工程的研究进展,并就其未来发展进行展望.     

蜘蛛丝拉伸变形行为的力学模型

根据大腹园蛛牵引丝力学性能的结构机理及其聚集态结构和形态结构特征，初步建立了以皮芯层结构为基础的蜘蛛丝拉伸力学模型，分析了皮芯层比例及结构对蜘蛛丝纤维力学性能的影响。以层状复合材料的拉伸变形为依据，分析了蜘蛛丝纤维的拉伸断裂过程与皮芯层性能间的关系。     

蜘蛛牵引丝蛋白的特性及其分子工程

蜘蛛牵引丝是由蜘蛛主壶腹腺产生的一种具有高度重复结构的蛋白质纤维，它将高抗张强度和高弹性奇妙地结合于一体，是自然界强度最高的纤维.基因解析揭示出牵引丝至少存在两种高度重复的蛋白组分，每种蛋白的重复单元都显示出富丙氨酸区和富甘氨酸区交替的模块结构特征. 采用分子工程技术不仅可以生产出具有天然牵引丝蛋白特性的重组蜘蛛丝蛋白，也可为研究牵引丝蛋白的模块结构与功能特性之间的关系开辟道路. 文中结合我们的研究综述了牵引丝蛋白的模块结构及其分子工程的研究进展，并就其未来发展进行展望.     

纤维之星——人造蜘蛛丝

小小的蜘蛛用体液抽出晶莹的长丝,编织一张张圆网,捕捉虫蛾为食物。人类从蜘蛛丝的突出优点中得到启示,正在努力实现人造蜘蛛丝的梦想。在这一领域中探寻的是美国康奈尔大学的应用生命研究所所长詹林斯教授。 天然蜘蛛丝的直径为习微米左右,其单位截面积的牵引强度相当于钢的5倍。蜘蛛丝还具有卓越的防水和伸缩功能。詹林斯教授认为,如果制造出一种具有天然蜘蛛丝特点的人造蜘蛛丝,那么这种丝就具有广泛     

Molecular Properties在海藻糖分子构象分析中的应用

应用Molecular Properties(MP)软件中内置的分子动力学计算功能,对海藻糖分子构象进行了研究,所得到的可能的最优构象的结构参数与文献报道数值基本吻合,表明了利用MP软件研究分子构象的可行性.按照XML 1.0标准编写了海藻糖分子可能的最优构象的CML格式分子结构文件,以便于网上交流和检索.     

Molecular Fundaments of Mechanical Properties of Spider Silk

Dragline, framework and cocoon silk fibers of Araneus Ventricosus were used for this study. To investigate the microstructure mechanisms of stress-strain behavior of spider silk, firstly, amino acid compositions were analyzed and molecular conformations and crystallinity were measured with Raman spectra and X-ray diffraction respectively. The results showed that there were more amino acids with large side groups and polar ones in spider silk than those of Bombyx silk, and the amino acid distribution varied with different spider silk. The molecular structures were mainlyα-helix and β-sheet, and random coil andβ-turn existed as well. The proportions and arrangement of these conformations of dragline silk were different from framework and cocoon silk fibers. Microstructure was one of important factors of excellent mechanical properties of spider silk. Crystallinity of spider silk was very low, which implied that the roles of crystal on spider silk were not as great as other protein fibers.     

Solid-state NMR determination of the secondary structure of Samia cynthia ricini silk

Silks are fibrous proteins that form heterogeneous, semi-crystalline solids. Silk proteins have a variety of physical properties reflecting their range of functions. Spider dragline silk, for example, has high tensile strength and elasticity, whereas other silks are better suited to making housing, egg sacs or the capture spiral of spiders' webs. The differing physical properties arise from variation in the protein's primary and secondary structure, and their packing in the solid phase. The high mechanical performance of spider dragline silk, for example, is probably due to a beta-sheet conformation of poly-alanine domains, embedded as small crystallites within the fibre. Only limited structural information can be obtained from diffraction of silks, so further characterization requires spectroscopic studies such as NMR. However, the classical approach to NMR structure determination fails because the high molecular weight, repetitive primary structure and structural heterogeneity of solid silk means that signals from individual amino-acid residues cannot be resolved. Here we adapt a recently developed solid-state NMR technique to determine torsion angle pairs (phi, psi) in the protein backbone, and we study the distribution of conformations in silk from the Eri silkworm, Samia cynthia ricini. Although the most probable conformation in native fibres is an anti-parallel beta-sheet, film produced from liquid directly extracted from the silk glands appears to be primarily alpha-helical.     

Nonlinear material behaviour of spider silk yields robust webs

Natural materials are renowned for exquisite designs that optimize function, as illustrated by the elasticity of blood vessels, the toughness of bone and the protection offered by nacre. Particularly intriguing are spider silks, with studies having explored properties ranging from their protein sequence to the geometry of a web. This material system, highly adapted to meet a spider's many needs, has superior mechanical properties. In spite of much research into the molecular design underpinning the outstanding performance of silk fibres, and into the mechanical characteristics of web-like structures, it remains unknown how the mechanical characteristics of spider silk contribute to the integrity and performance of a spider web. Here we report web deformation experiments and simulations that identify the nonlinear response of silk threads to stress--involving softening at a yield point and substantial stiffening at large strain until failure--as being crucial to localize load-induced deformation and resulting in mechanically robust spider webs. Control simulations confirmed that a nonlinear stress response results in superior resistance to structural defects in the web compared to linear elastic or elastic-plastic (softening) material behaviour. We also show that under distributed loads, such as those exerted by wind, the stiff behaviour of silk under small deformation, before the yield point, is essential in maintaining the web's structural integrity. The superior performance of silk in webs is therefore not due merely to its exceptional ultimate strength and strain, but arises from the nonlinear response of silk threads to strain and their geometrical arrangement in a web.     

Surprising strength of silkworm silk

Commercial silkworm silk is presumed to be much weaker and less extensible than spider dragline silk, which has been hailed as a 'super-fibre'. But we show here that the mechanical properties of silkworm silks can approach those of spider dragline silk when reeled under controlled conditions. We suggest that silkworms might be able to produce threads that compare well with spider silk by changing their spinning habits, rather than by having their silk genes altered.     

Morphology and Microstructure of Spider Dragline Silk from Araneus Ventricosus

The spider dragline silk has excellent mechanical properties. The stress- strain curves of dragline silk fibers have intraspecific and intraindividual variability because of the spiders active control during spinning process. To investigate the relationship between the morphology of dragline silk fibers and spinning conditions, four samples were made at the reeling rates of 1mm/s, 20mm/s, 43.5mm/s and 110mm/s from the major ampullate glands of Araneus Ventricosus and the other two of dragline silks were prepared from a crawling or dropping spider. The surface microstructure and nanofibril characteristic were analyzed with atomic force microscopy (AFM). AFM images of 2000nm*2000nm and 500nm*500nm of these samples showed that the spinning condition influenced the surface roughness and fibril size, while AFM images of 200nm*200nm clearly displayed that dragline silk of Araneus Ventricosus included sheet macro-conformation structure. These results can facilitate the further investigation of the spinning mechanism of a spider in order to understand mechanical properties and macromolecular structures of dragline silk.     

蜘蛛丝蛋白的研究进展

蜘蛛丝属线状蛋白质,具有独特的结构和性能特点,是世界上拉力强度和弹性最强的纤维之一,其强度比钢还要硬.一些蜘蛛丝蛋白的基因已被克隆出来,并且用不同的表达载体表达,同时进行了成丝研究.由于蜘蛛丝性能独特,在许多领域具有良好的应用前景.     

大腹圆蛛包卵丝的化学组成与物理机械性能

分析了大腹圆蛛包卵丝的氨基酸组成，包卵丝中极性氨基酸含量较高，小侧基氨基酸含量较少，利用SEM及计算机图像处理技术分析了大腹圆蛛包卵丝的形态结构特征，包卵丝的断面形状基本为圆形，包层包卵丝的细度约为内层包卵丝的2倍，并且外层包卵丝的纤维断面内有许多无规分布的纳米级孔隙，经冷冻干燥后，孔隙率增加了2倍左右，在此基础上，研究了大腹圆蛛包卵丝的拉伸机械性能，光泽和热性能，初步探索了性能的形成机理，大腹圆蛛内层包卵丝具有比其他功能蜘蛛丝和丝素纤维好得多的力学性能，其强度高，伸长率大，韧性好，包卵丝在光泽和热性能方面与蚕丝丝素纤维有一定的差异。