共查询到20条相似文献,搜索用时 156 毫秒
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论述近十年来有关准晶体结构在生物组织中的研究和发现,对中Kedves提出的生物聚合体准晶体结构和其三维构象进行了分析。介绍了其研究方法,指出其结构存在之不足。 相似文献
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《生物矿物学》一书评介《生物矿物学》是一门新兴的生物地质学基础分文学科。生物矿物学的研究对象是生物矿物及其集合体─-生物矿物体。其研究内容包括生物矿物的化学成分、晶体结构、结晶形态、物理和化学性质、生理功能和产状;生物矿物体的物质组成、结构构造、形态... 相似文献
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研究蛋白质和配体相互作用的结构和亲和力,不仅有助于了解蛋白质的功能,而且对药物研发以及药物作用机制的研究,也具有十
分重要的意义。目前,人们通过人工检索和半自动检索的方式,从文献和蛋白质数据库(Protein Data Bank,PDB)中获得了许多蛋白质-
配体亲和力信息和生物相关配体信息,并构建了许多蛋白质-配体相互作用的信息数据库。对3 个蛋白质-配体亲和力数据库和6 个蛋白质
晶体结构-配体生物相关性数据库进行介绍,并对其主要应用进行简述,希望能为实现高效准确地筛选和设计药物提供一定的帮助。 相似文献
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王大成 《中国生物化学与分子生物学报》1987,3(4):289-300
<正> 自从五十年代末成功地运用X射线衍射分析技术测定肌红蛋白分子的晶体结构以来,我们关于蛋白质在三维水平的结构及其与功能关系的认识,已经历了两个阶段。第一个阶段包括60年代初至70年代中期。在这一期间,解决了蛋白质晶体结构测定方法的一般化问题,使以同晶置换法为主的一套X射线衍射分析技术成为研究生物大分子三维结构的成熟手段,给 相似文献
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苔藓植物参与岩溶作用的过程是生物岩溶的重要内容。开展苔藓植物岩溶作用研究可为石漠化裸岩的生态恢复及其综合治理提供理论依据和技术支撑。该文系统论述了苔藓植物岩溶作用的过程(溶蚀与沉积)、机理及其与生境互作机制的最新研究进展。苔藓植物及其生物结皮在干湿交替下发生膨胀、卷缩、冻融等物理机械力, 以及其代谢分泌物和因呼吸作用而产生的H2CO3与岩石中矿物反应, 破坏矿物晶体结构, 导致矿物裂解、使岩面崩解脱落而改变岩面形态, 塑造岩溶地貌, 形成原始土壤。苔藓植物岩溶作用驱动力的大小与植物功能性状、基岩性质与生存环境密切相关。此外, 生物岩溶作用需要长时间尺度的监测, 研究周期长, 建议建立野外长期监测基地, 加强对其内在机制与过程以及与生境间互作机制, 苔藓植物的生理代谢过程及其生物酶等与岩溶作用的相互关系, 岩溶地区苔藓植物环境适应性特征及其生物多样性维持机制等方面的研究。 相似文献
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The conditions for the formation and stability of quasi-crystal helical structures formed of charged dust grains of equal size in a complex plasma are investigated. A study is made of both the transverse confinement of such structures by means of an external parabolic potential well and the possibility of their self-confinement or confinement by the field of the smaller background grains. It is shown that, in the presence of dissipation, any initial random distribution of dust grains in a cylindrical external potential evolves into an equilibrium helical structure with a constant pitch angle. It is found that, when the external control parameter is smoothly varied, the pitch angle of the helix changes abruptly and the structure of the quasi-crystal undergoes bifurcations, during which the number of interwoven helices changes. The smaller the confinement parameter and the weaker the attractive forces between the grains, the larger the number of bifurcations. In addition, it is found that, because of the attraction (both noncollective and collective) between the dust grains, stable helical structures may exist not only at zero value of the external confinement parameter, but also at a negative one, and that the collective interaction between the grains not only increases the number of bifurcations but also changes their character. 相似文献
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Crystallographic analysis of acrosomal bundle from Limulus sperm 总被引:5,自引:0,他引:5
M F Schmid P Matsudaira T W Jeng J Jakana E Towns-Andrews J Bordas W Chiu 《Journal of molecular biology》1991,221(2):711-725
The acrosomal process of Limulus sperm contains a bundle of filaments composed of actin and a 102 kDa protein in a 1:1 molar ratio. The structure of the bundle in true discharge was investigated by electron cryomicroscopy, X-ray scattering and crystallographic image analysis. A bundle can be characterized as a quasi-crystal with continuously varying views along the bundle axis. Each segment of the bundle is found to obey the symmetry of space group P1, with a = b = 147 A, c = 762 A, alpha = 90 degrees, beta = 90.6 degrees, gamma = 120 degrees. A unit cell contains a helical repeat of the filament with a selection rule following that of an actin filament. A 24 A projection map based on the h0l view was reconstructed after averaging 5300 unit cells from six electron images. Filaments in this projection are well separated and clearly display a 21 screw symmetry. This screw symmetry results from the helical parameters of the bundle filament and is found to be a non-crystallographic symmetry element present in the unit cell. Our structural analysis has led to the proposal that the assembly of a stable bundle with a defined maximum diameter can be controlled by the crystallographic packing of the twisted filaments. 相似文献
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Iwamoto H Oiwa K Kovács M Sellers JR Suzuki T Wakayama J Tamura T Yagi N Fujisawa T 《Journal of molecular biology》2007,369(1):249-264
Low-resolution three-dimensional structures of acto-myosin subfragment-1 (S1) complexes were retrieved from X-ray fiber diffraction patterns, recorded either in the presence or absence of ADP. The S1 was obtained from various myosin-II isoforms from vertebrates, including rabbit fast-skeletal and cardiac, chicken smooth and human non-muscle IIA and IIB species, and was diffused into an array of overstretched, skinned skeletal muscle fibers. The S1 attached to the exposed actin filaments according to their helical symmetry. Upon addition of ADP, the diffraction patterns from acto-S1 showed an increasing magnitude of response in the order as listed above, with features of a lateral compression of the whole diffraction pattern (indicative of increased radius of the acto-S1 complex) and an enhancement of the fifth layer-line reflection. The structure retrieval indicates that these changes are mainly due to the swing of the light chain (LC) domain in the direction consistent with the cryo-electron microscopic results. In the non-muscle isoforms, the swing is large enough to affect the manner of quasi-crystal packing of the S1-decorated actin filaments and their lattice dimension, with a small change in the twist of actin filaments. Variations also exist in the behavior of the 50K-cleft, which apparently opens upon addition of ADP to the non-muscle isoforms but not to other isoforms. The fast-skeletal S1 remains as the only isoform that does not clearly exhibit either of the structural changes. The results indicate that the "conventional" myosin-II isoforms exhibit a wide variety of structural behavior, possibly depending on their functions and/or the history of molecular evolution. 相似文献
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从植物中寻找农药活性物质 总被引:5,自引:0,他引:5
朱正方 《天然产物研究与开发》1992,4(3):73-88
从植物中寻找农药活性物质,判明结构,使之成为创新类型农药有效母体,是创制新农药品种的重要途径之一,受到当今全世界农药界的广泛重视。本文综合性介绍植物与农药的关系,该交叉学科研究的一般程序和方法以及通过对有效母体的结构改造,构一效关系的研究,创制新农药的研究过程。 相似文献
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同步辐射的发展和应用已经极大的推动了自然科学包括生物学的巨大发展,其中结构生物学更是离不开X射线衍射分析,小角散射等。X射线自由电子激光(XFEL)相比同步辐射具有更高强度,完全相干等特点,被称为第四代光源。科学家已经利用XFEL实现了尺度约为1微米的蛋白质晶体的高分辨率结构解析,并且也实现了单颗粒的病毒的低分辨重构。未来,XFEL将会为生物学的发展打开一扇新的大门。 相似文献
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荧光晕法是近年来发展起来的定量检测细胞染色质结构状态的方法,由于其简易、直观、灵敏、快速,已被广泛用于放射生物学及肿瘤细胞生物学研究中。我们依据文献报道建立了此法,并对其进行了改良,进一步优化了操作步骤。并用该法检测了两种相同来源(具有相似遗传背景)、具不同辐射敏感性的细胞株的染色质结构状态,发现辐射敏感株SX-9具有更松散的染色质结构,可能与两者的辐射敏感性差异有关,为研究染色质结构状态与辐射敏感性的关系提供了佐证。 相似文献
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青藏铁路温性草原区铁路运营对啮齿动物群落结构的影响 总被引:5,自引:0,他引:5
以青藏铁路海晏段的温性草原区为研究地点,通过铗日法确定距离铁路不同距离的区域中啮齿动物的种群密度和群落结构,分析啮齿动物群落结构与植物群落结构之间的关系,探讨温性草原区铁路运营对啮齿动物群落结构的影响。结果表明,研究区域内所捕获的啮齿动物有甘肃鼠兔、五趾跳鼠、长尾仓鼠和灰仓鼠;从1984 年铁路投入运营以来,没有发现铁路运营带来新物种的入侵;啮齿动物的种群密度和群落结构在距离铁路不同距离的样带之间有明显的不同,在铁路路基附近的种群密度、物种数、多样性指数均明显高于距离铁路0.5 km和1 km的区域,而均匀性指数在路基附近最小;在距离铁路不同距离的区域中植物群落的特征没有明显差异,啮齿动物群落特征与植物群落特征之间没有明显的相关性。引起铁路路基附近啮齿动物种群密度、物种数、多样性指数偏高的原因可能是铁路修建与运营为啮齿动物提供了合适的生存环境与额外的食物资源。因此,铁路建设及运营对啮齿动物的群落结构有一定程度的影响。 相似文献
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细菌视紫红质研究的新进展 总被引:7,自引:0,他引:7
细菌视紫红质(bR)自六十年代末发现以来,一直是膜蛋白领域研究的热点之一,bR不仅在基础理论研究方向有着深远的意义,而且也有着广泛的应用前景。对bR的结构、质子泵功能、折叠机制等研究前沿进行概述。 相似文献