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Chinese Physics Letters 2002年第11期19卷 1727-1729页

作者：王敖金胡坤生 instituteofbiophysics ChineseAcademyofSciencesBeijing100101

Membrane viscosity of the reconstituted vesicles was calibrated by rotational diffusion of bacteriorhodopsin (BR) in dimyristoylphosphatidylcholine (DMPC) and egg phosphatidylcholine (PC) vesicles. Rotational diffusion of BR in the vesicles was measured by flash-induced absorption anisotropy decay. BR was, for the first time, reconstituted successfully into DMPC and egg PC vesicles. From the measurement of flash-induced absorption anisotropy decay of BR, the value of rotational diffusion coefficient D was obtained from each curve fitting by a global fitting procedure and, in turn, membrane viscosity η was estimated from D. The results have shown that membrane viscosity is temperature-dependent. It was decreased as temperature increased, but a transition occurred in the region of the respective phase transition of DMPC and egg PC, respectively. The decrease of η was fast near the phase transition for DMPC and egg PC. Few effects of lipid/BR ratio and glycerol or sucrose in suspension medium on membrane viscosity were found.

关键词： Curve fitting

Scaling Behaviour of Conserved Sites in Protein Families

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Chinese Physics Letters 2005年第5期22卷 1274-1277页

作者：李捷王骏王炜 NationalLaboratoryofSolidStateMicrostructure InstituteofBiophysicsandDepartmentofPhysicsNanjingUniversityNanjing210093

Base on the database of families of structurally similar proteins, a statistical study is made on the scaling behaviour of occupying probabilities of conserved sites (Pc) in various protein families. A power-law decrease of Pc with the increasing protein-chain length Lf is found. This is related to the power-law scaling behaviour of the occurring probabilities of local contact interactions (Plocal) between residues. In addition, applying residue grouping, we find the same scaling behaviour when the number of residue types is more than 12, indicating that 12 residue types are enough to present the complexity of proteins.

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cDNA cloning and expression of earthworm fibrinolytic enzyme component A

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Chinese Science Bulletin 2003年第1期48卷 68-71页

作者： LIUJunfeng WANGXinquan 等 NationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100101China NationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100

Earthworm fibrinolytic enzyme component A (EFEa), a protein with dual fibrinolytic activity, is one of the major therapeutically important earthworm fibrinolytic enzyme components. The cDNA fragment encoded the ma-ture protein was cloned from earthworm (Eisenia fetida) by the RT-PCR technique. The deduced amino acid sequence of the EFE component A shows high homology with some members of serine proteases trypsin family, and the amino acid residues constituting the active sites are conserved in the EFEa as compared with the other proteins of the trypsin family. The cDNA fragment was subcloned into the expres-sion vector pQE31 and pMAL-c2X of E. coli. The resulting expression plasmids, pQE-efea and pMAL-efea, were used to transform the E. coli strain M15. Recombinant protein bands corresponding with calculated molecular weights were induced. The induced His6-EFEa fusion protein with pQE- efea was accumulated into inclusion body, while the induced MBP-EFEa fusion protein with pMAL-efea was soluble and showed fibrinolytic activities.

关键词：蚯蚓纤溶酶成分A cDNA 基因克隆基因表达

Statistical analysis on protein-protein interface in crystals: Specific and non-specific interfaces are differentially distributed

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Chinese Science Bulletin 2004年第3期49卷 273-276页

作者： FENGDan ZENGZonghao instituteofbiophysics ChineseAcademyofSciencesBeijing100101China

The distribution of contact areas, or fractions of contacting, of protein-protein interfaces in crystals of pure polypeptides contains two components: a major exponential distribution and a minor flatter distribution. Suppose the two components belong to specific and non-specific contacts,respectively, then the probability of a contact with a givena rea, or fraction of contacting, can be estimated. By dividing the whole database into two sub-databases, one of them is known to contain more specific contacts than the other, this hypothesis is confirmed and it is also proved that the fraction of contacting is more effective than the contact area on discriminating specific and non-specific contacts in protein crystals.

关键词：缩多氨酸指数分布蛋白质结晶晶体结构

Gene expression regulators——MicroRNAs

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Chinese Science Bulletin 2005年第13期50卷 1281-1292页

作者： CHENFang YINQ.James NationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100101China//GraduateSchoolofChineseAcademyofSciencesBeijing100039China NationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100101China

A large class of non-coding RNAs found in small molecule RNAs are closely associated with the regula-tion of gene expression, which are called microRNA (miRNA). MiRNAs are coded in intergenic or intronic regions and can be formed into foldback hairpin RNAs. These transcripts are cleaved by Dicer, generating mature miRNAs that can silence their target genes in different modes of action. Now, research on small molecule RNAs has gotten breakthrough advance in biology. To discover miRNA genes and their target genes has become hot topics in RNA research. This review attempts to look back the history of miRNA discovery, to introduce the methods of screening miRNAs, to localize miRNA loci in genome, to seek miRNA target genes and the biological func-tion, and to discuss the working mechanisms of miRNAs. Finally, we will discuss the potential important roles of miRNAs in modulating the genesis, development, growth, and differentiation of organisms. Thus, it can be predicted that a complete understanding of miRNA functions will bring us some new concepts, approaches and strategies for the study of living beings.

关键词： RNA 基因表达生物无机化学遗传学

Direct observation of the clockwise light-driven rotation of F_0F_(1-)ATP synthase complex

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Chinese Science Bulletin 2004年第13期49卷 1342-1347页

作者： CUIYuanbo ZHANGYinghao YUEJiachang JIANGPeidong TheNationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100101China//TheGraduateSchoolofChineseAcademyofSciencesBeijing100039China TheNationalLaboratoryofBiomacromolecules InstituteofBiophysicsChineseAcademyofSciencesBeijing100101China

The purified thermophilic bacterium PS3 F1β10×His-tag is inserted into the F0F1-ATP synthases of chromatophores isolated from photosynthetic bacteria Rhodospirillum rubrum. The studies of biochemical properties of the hybrid chromatophores show that they have both protons-driving capability and photophosphorylation. The fluorescent actin filaments, as a marker of its orientation by video-microscopic experiment, are connected via Maleimido-C3-NTA to the reconstituted β10×His-tag of F0F1-ATP *** clockwise rotation of FoFt-ATP synthases driven by light is observed directly when viewed from the Fo side to Ft. This system should be valuable for further studying the coupling property of F0F1-ATP synthase.

关键词： FoF1-ATP酶色素体光合作用顺时针旋转光驱策分子运动光合细菌色谱电泳

Mechanical Properties of Breast Cancer Cell Membrane Studied with Optical Tweezers

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Chinese Physics Letters 2004年第12期21卷 2543-2546页

作者：郭红莲刘春香段建发隆雨强韩学海李兆霖程丙英张道中 OpticalPhysicsLaboratory InstituteofPhysicsChineseAcademyofSciencesBeijing100080 StateKeyLaboratoryofBiomacromolecles InstituteofBiophysicsChineseAcademyofSciencesBeijing100101

Membrane tethers are extracted from breast cancer cells using a force generated by an optical trap. It is experimentally obtained that the radius of tether is about 0.1μm and the static tether force is about 8.5pN. Calculations based on the experimental measurements give a bending modulus for the tether of 1.35×10−19N.m and a surface membrane tension of 6.76×10−6N/m in the breast cancer cell. The treatment with cytochalasin D results in the decreasing bending modulus and decreasing apparent surface tension. When the membrane protein caveolin is over-expressed, similar cases occur in bending modulus and apparent surface tension. In addition, the viscous resistance coefficient of the membrane is calculated to be 1.15pN.s/μm according to the dynamic tether forces obtained under different pulling velocities.

关键词： Surface tension

Displacement and Force Measurements with Quadrant Photodetector in Optical Tweezers

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Chinese Physics Letters 2003年第6期20卷 950-952页

作者： GUOHong-Lian LIUChun-Xiang LIZhao-Lin DUANJian-Fa HANXue-Hai CHENGBing-Ying ZHANGDao-Zhong OpticalPhysicsLaboratory InstituteofPhysicsandCenterforCondensedMatterPhysicsChineseAcademyofSciencesBeijing100080 StateKeyLaboratoryofBiomacromolecles InstituteofBiophysicsChineseAcademyofSciencesBeijing100101

A technique of displacement and force measurements with a photodiode quadrant detector in an optical tweezers system is presented. The stiffness of optical trap is calibrated and the leukemia cell membrane tension is measured. The results show that the optical tweezers combined with the quadrant detector is a very useful tool for detecting the displacement and force with a millisecond-order response.

关键词： Optical tweezers

Topography of acoustic response characteristics in the midbrain inferior colliculus of Kunming mouse

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Chinese Science Bulletin 2003年第2期48卷 161-165页

作者： SHENJunxian XUZhimin 等 CenterforBrainandCognitiveScience.LaboratoryofVisualInformationProcessing.instituteofbiophysics ChineseAcademyofSciencesBeijing100101China CenterforBrainandCognitiveScience.LaboratoryofVisualInforma

Topography of acoustic response characteris-tics of the midbrain inferior colliculus (IC) of the Kunming mouse was studied by using extracellular recording tech-niques. The characteristic frequency (CF) range represented in the different divisions of the IC differed markedly: 4—15 kHz in the dorsal cortex (DC), 10—70 kHz in the centralnucleus (CN), and 4—35 kHz in the external cortex (EC).The CF in the CN increased from dorsal and lateral to ven-tral and medial, higher CFs represented at its ventromedial part and lower CFs at its dorsal part. The isofrequency con-tours of CFs were incurvate. Minimum thresholds (MT) ofthe auditory neurons in DC and the central part of CN were lower (about 10 dB SPL), but considerably higher in thedorsal and ventral region of EC. Results suggest that each of the divisions in the mouse IC may have different auditory functions.

关键词：昆明小白鼠中脑四叠体下丘听觉反应听神经阈值

A generalized approach for protein design based on the relative entropy

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Chinese Science Bulletin 2004年第5期49卷 426-431页

作者： WANGYihua WANGBaohan LIUYun CHENWeizu WANGCunxin CollegeofLifeScienceandBioengineering BeijingUniversityofTechnologyBeijing100022China instituteofbiophysics(IBP) ChineseAcademyofSciencesBeijing100101China

In the present study, we have developed the method brought forward recently for protein design based on the relative entropy. The new approach can be used in more common situation other than the special limits in the anterior method. The results indicate that our generalized method has increased the prediction precision for protein sequence and will be in favor of the study for protein design.

关键词：蛋白质设计相对熵逆蛋白展开分子生物学