蛋白质结构的分形及其与进化关系的研究

本文在应用分形理论对蛋白质分子结构的分形进行研究的基础上,从非线性角度,就蛋白质多肽链的结构与形以及球蛋白三维结构的分形与进化的关系问题,进行了理论探讨和分析。     

兴安落叶松分枝格局的分形特征

对于树木分枝格局分形特征的定量描述,可以加深对树木生长过程的理解。本文采用分形几何学对兴安落叶松(Larix gmelini)的分枝格局进行研究,结果表明1)兴安落叶松分枝格局是一种分形结构,存在自相似性。2)兴安落叶松分枝格局的分形维数介于1.4~1.7之间,揭示了它的结构复杂性程度和占据生态空间、利用生态空间的能力。分形维数在树木光合作用及生长发育研究中是一个有用的参数。     

兴安落叶松分枝格局的分形特征

对于树木分枝格局分形特征的定量描述,可以加深对树木生长过程的理解。本采用分形几何学对兴安落叶松（Ｌａｒｉｘ ｇｍｅｌｉｎｉ）的分枝格局进行研究,结果表明１）兴安落叶松分枝格局是一种分形结构,存在自相似性。２）兴安落叶松分枝格局的分形维数介于１．４－１．７之间,揭示了它的结构复杂性程度和占据生态空间、利用生态空间的能力。分形维数在树木光合作用及生长发育研究中是一个有用的参数。     

蛋白质复合体及蛋白质相互作用研究新策略—化学交联结合质谱分析法

近年来化学交联法结合质谱分析法被广泛用于蛋白质复合体结构及蛋白质相互作用的研究。研究表明这两种方法的有机结合为研究蛋白质复合体结构及蛋白质相互作用提供了一条新的途径。文章对不同类型的化学交联剂、质谱分析中的Bottom-up 与Top-down 两种研究策略,以及化学交联法结合质谱分析法在蛋白质复合体结构、蛋白质相互作用研究中的应用进行综述。这两种方法的不断发展与完善,将会极大促进生物大分子复合体结构及蛋白质相互作用的研究。     

蛋白质中原子与基团的可及性的一种新计算方法及其应用

实现了一种新的蛋白质中原子层次可及面积的计算方法－Ｍｏｎｔｅ－Ｃａｒｌｏ模拟方法。计算了溶菌酶各个原子与功能基团的可及性,并应用于蛋白质结构和功能的研究中。使得对蛋白质性能的预测更准确,提供了一种对蛋白质结构和功能研究的新思路。     

金属硫蛋白1及其"结"结构

随着蛋白质结构计划的顺利开展,各种各样的蛋白质结构将被科学家破译。“结”结构就是最近被发现的一种蛋白质新结构。本文主要论述了在产甲烷杆菌(Methanobacterium thermoautotrophicum)中含有“结”结构的MTl蛋白质的结构研究新成果。     

平行β螺旋──一种新的蛋白质立体结构

平行β螺旋──一种新的蛋白质立体结构王克夷（中国科学院上海生物化学研究所,上海２０００３１）关键词平行β螺旋,蛋白质立体结构,果胶酸裂解酶借助蛋白质结晶学和核磁共振的研究,不仅已测定许多蛋白质的立体结构,也揭示了蛋白质的三维结构有一定规律可循,并可将...     

木本植物对喀斯特石质生境岩石形态结构的适应性

为弄清植物对喀斯特岩石形态结构的适应性,选择3种岩石类型及7种木本群落为研究对象,基于分形、空间句法理论研究岩石结构面孔裂隙形态结构及其与群落特征的关系。结果表明:石灰岩结构面孔裂隙间隙度大、白云岩居中、白云质砂岩小,分维数则反之;白云质砂岩结构面孔裂隙整合度、控制值、密度值大,白云岩居中,石灰岩小;白云岩生境下群落物种多样性及优势种碳、氮含量高、白云质砂岩次之、石灰岩低;分形与空间句法指数间呈显著相关关系,两者能较好的揭示岩石形态结构;总体上3种岩性生境下物种多样性及优势种碳、氮含量与岩石结构面孔裂隙分形及空间句法指数具较强相关关系;大致相同的环境下白云岩形态结构适宜植物生长、白云质砂岩次之、石灰岩差;研究岩石形态结构对喀斯特植被恢复具有重要意义。     

分形在电力故障检测中的应用

目前我国电力高速发展,对电力系统故障检测提出新的挑战,电力输电线检测成为新的研究热点,分形及多重分形理论作为一种研究非线性科学的有力的数学工具,可以有效描述不同信号不同物体在分形特征上的差异。本文首先对电力系统故障传统检测方法进行了说明,接下来阐述了分形及多重分形理论,最后分析了电力输电线故障在分形特征上的差异,介绍了利用分形和多重分形特征进行电力故障检测的方法。     

病毒衣壳蛋白的解离和重组

在生物微观世界中,某些病毒的结构形态是迄今为止研究得比较透彻的一种。病毒的衣壳蛋白在完成其生物功能——即和病毒核酸的相互作用,而后形成包裹衣壳,是自然界中蛋白质聚合成高级结构(四级结构)的一种典型的有序模型。目前,为数不少的病毒,包括植物、动物及细菌病毒的衣壳蛋白一级结构已经阐明,因此病毒的衣壳蛋白是研究蛋白质的解离、聚合、装配和重组,蛋白质各级结构之间的关系及蛋白质和核酸之间相互作用等问题的一个极好对象。对于病毒衣壳蛋白的解离和重组过程,已有不少研究报道、综述和专著     

The structure, catalytic mechanism and regulation of adenylyl cyclase

The recent structure determinations of the mammalian effector enzyme adenylyl cyclase reveal the structure of its catalytic core, provide new insights into its catalytic mechanism and suggest how diverse signaling molecules regulate its activity.     

Ab initio structure of human seminal plasma prostatic inhibin gives significant insight into its biological functions

Human seminal plasma prostatic inhibin (HSPI) is a protein isolated from the human prostate gland. Despite its profound biomedical and biotechnological importance, the 3D structure of this protein of 94 amino acids remains undeciphered. The difficulties in extracting it in pure form and crystallizing it have restrained the determination of its structure experimentally. The homology-based computational methods are also not applicable, as HSPI lacks sufficient sequence homology with known structures in the protein data banks. We have predicted the structure of HSPI by a knowledge-based method using nonparametric multivariate statistical techniques. Stereochemical and other standard validation tests confirm this to be a well-refined structure. The biophysical properties exhibited by this structure are in good agreement with the NMR experimental observations. Docking and other computational studies on this structure provide significant explanation and insight into its binding activities and related biological and immunogenic functions and offer new directions for its potential applications.     

The crystal structure of yeast phenylalanine tRNA at 1.93 A resolution: a classic structure revisited

The crystal structure of the monoclinic form of yeast phenylalanine tRNA has been redetermined at a resolution of 1.93 A. The structure of yeast tRNAphe described here is more accurate than its predecessors not only because it incorporates higher resolution data, but also because it has been refined using techniques that had not been developed when its predecessors were determined more than 20 years ago. The 1.93 A resolution version of this structure differs interestingly from its predecessors in its details. In loop regions particularly, the backbone torsion angles in the new structure are not the same as those reported earlier. Several new divalent cation binding sites have been identified, and the water structure that has emerged is also different.     

植物炭疽病真菌金属硫蛋白的三级结构预测

根据实验测定的Ⅰ类金属硫蛋白(metallothionein, MT)三级结构的实验数据,给出该类蛋白质的两种特征结构(CXC、CXXC一级结构,半胱氨酸-金属络合簇三级结构)的原子间距离约束条件,然后运用距离几何算法计算出一系列可能的构象.从这些构象中经统计分析筛选出目标函数值显著较小的结构作为所预测蛋白质的三级结构模型.用已知结构的蓝蟹MT对方法进行检验证实其可行性后,对植物炭疽病真菌金属硫蛋白CAP3进行了三级结构预测.     

肝素结构与功能的研究进展

肝素是一类结构异常复杂的糖胺聚糖,与此相对应的是其多种生物学功能。除了经典的抗凝血及其相关的抗血拴生成以外,肝素还具有抗平滑肌细胞增殖、抗炎症、抗肿瘤及抗病毒等,并且这些生物活性同抗凝活性无关,而同肝素的特异结构密切相关。本文综述了肝素的多种生物学功能、作用机制及结构与功能的关系。     

金属硫蛋白—3研究进展

金属硫蛋白－3（MT－3）是近年来发现的一种脑特异性金属硫蛋白。本文综述了其在分布、蛋白结构及基因调控方面的特点;着重介绍了其在中枢神经系统中的功能及结构与功能关系的研究进展;总结了国外对其与老年痴呆症的可能关系的研究。     

A club-shaped hair found on the first-instar nymphs of Schistocerca gregaria

A receptor found mainly on the antero-dorsal regions of the first-instar nymph of Schistocerca gregaria is described. The fine structure of the sensillum and its associated cells is described and its possible functions discussed in relation to its unusual structure.     

The paraflagellar rod of kinetoplastida: solved and unsolved questions

The flagellum of almost every member of the Kinetoplastida contains, next to its canonical 'nine-plus-two' axoneme, structure, a unique, complex and highly organized lattice-like structure called the paraflagellar rod or paraxial rod. Here, Philippe Bastin, Keith Matthews and Keith Gull summarize the latest findings on its structure, the nature of its protein components and their corresponding genes. They also consider the possible functions of this intriguing organelle.     

Can the fluorescence of green fluorescent protein chromophore be related directly to the nativity of protein structure?

In studies of green fluorescence protein (GFP) or other proteins with the use of GFP as a marker, the fluorescence of GFP is for the most part related directly to the nativity of its structure. Naturally, such a relation does exist since the chromophore of this protein is formed autocatalytically only just after GFP acquires its native structure. However, the fluorescence method may not yield reliable information on protein structure when studying renaturation and denaturation of this protein (with the formed chromophore). Using proteolysis, denaturant gradient gel electrophoresis and circular dichroism, we demonstrate herein that at major disturbances of the native structure of protein GFP-cycle3 the intensity of fluorescence of its chromophore can change insignificantly. In other words, the chromophore fluorescence does not reliably mirror alterations in protein structure. Since the main conclusions of this study are especially qualitative, it can be suggested that during renaturation/denaturation of wild-type GFP and its “multicolored” mutants their fluorescence is also not always associated with the changes in the structure of these proteins.     

Appendix: Structure and conformation of bilirubin. Opposing views that invoke tautomeric equilibria, hydrogen bonding and a betaine may be reconciled by a single resonance hybrid

A novel conformational structure of bilirubin is presented which obtains maximum stabilization through a system of four intramolecular hydrogen bonds. Two hydrogen bonds link oxygen and nitrogen atoms of each end ring to the contralateral carboxyl group. The proposed structure can explain a variety of uncommon features of bilirubin, and reconciles many seemingly contradictory hypotheses by accommodating them in individual structures which are mesomeric forms of one resonance hybrid. In the light of this newly conceived structure the following characteristics of bilirubin are re-evaluated: the stability of the compound, its reaction with diazomethane, the conformational behaviour of its dimethyl ester, its spectral properties, the chirality of the compound when complexed to serum albumin, and the structure of its metal chelates.