用MXAN拟合钩端螺旋体去甲酰化酶XANES谱

钩端螺旋体去甲酰化酶(Leptospira interrogans PDF)是一种重要的含锌金属蛋白酶, 对钩端螺旋体这一广泛存在的致病菌的蛋白合成起着关键的催化作用, 是一个很好的药物设计靶蛋白. 本文测试了LiPDF在pH3.0的溶液状态下的X射线吸收近边结构(XANES: X-Ray Absorption Near-Edge Structure)谱, 利用以从头计算(ab. initio)的多重散射(Multiple Scattering)为基础的MXAN方法确定金属蛋白活性中心的精细结构. 研究发现结合合适的初始结构模型, 可以更好地重现LiPDF蛋白的XANES曲线, 从而能够得到更加准确的结构参数. 活性中心的精细结构为理解LiPDF的pH依赖的催化活性提供了结构基础.     

钙钛矿CaTiO3的超高压结构研究

利用同步辐射x射线衍射和 DAC 高压技术在室温下测量了钙钛矿CaTiO₃在压力0—44.53 GPa下的结构变化.结果表明，随着压力的增加CaTiO₃的三个晶轴都受到不同程度的压缩，a,b的压缩率相近且相对比较大，c的压缩率最小，但没有证据表明有相变的发生.在压力范围内CaTiO₃的P-V关系用Murnaghan状态方程表示，设定K′0=4，得到V0=0.2245(6)nm3和K0=222(9) GPa.应用赝立方角γpc与压力的关系，初 关键词： 3')" href="#">CaTiO₃ 结构 超高压 状态方程     

β-FeSi2的高压研究

 对β-FeSi₂晶体进行了原位X射线衍射高压研究。利用同步辐射X射线衍射原位研究了β-FeSi₂的高压相演化，发现压力在4.3 GPa时出现相变，在25.8 GPa时相变完成。指标化结果表明：经高压处理后得到的产物具有四方结构，其晶格常数为：a=b=1.004 9 nm，c=0.339 4 nm。     

Solution of the effects of twinning in femtosecond X-ray protein nanocrystallography

With the development of the XFEL (X-ray free electron laser), high quality diffraction patterns from nanocrystals have been achieved. The nanocrystals with different sizes and random orientations are injected to the XFEL beams and the diffraction patterns can be obtained by the so-called "diffraction-and-destruction" mode. The recovery of orientations is one of the most critical steps in reconstructing the 3D structure of nanocrystals. There is already an approach to solve the orientation problem by using the automated indexing software in crystallography. However, this method cannot distinguish the twin orientations in the cases of the symmetries of Bravais lattices higher than the point groups. Here we propose a new method to solve this problem. The shape transforms of nanocrystals can be determined from all of the intensities around the diffraction spots, and then Fourier transformation of a single crystal cell is obtained. The actual orientations of the patterns can be solved by comparing the values of the Fourier transformations of the crystal cell on the intersections of all patterns. This so-called "multiple-common-line" method can distinguish the twin orientations in the XFEL diffraction patterns successfully.     

用ARUPS研究在Cs/Ru(1010)面上的CO分子轨道对称性

用同步辐射角分辨紫外光电子能谱对CO与Cs在Ru(1010)面上共吸附的研究结果表明,由于Cs的强烈影响,CO的分子轨道重新排列.对应清洁表面上CO分子的(5σ+1π)轨道的7.5eV谱峰分裂成两个,分别处于6.3和7.8eV,6.3eV谱峰关于一个垂直于Ru(1010)面而平行于〈0001〉晶向的镜象面反对称性. 关键词：     

Solution conformation of the response regulator proteins from Deinococcus radiodurans studied by SAXS

In this paper the solution conformation of the response regulator proteins from Deinococcus radiodurans was studied by small-angle X-ray scattering (SAXS). The SAXS curves of Dr-rrA in solutions were obtained at Beamline 1W2A of Beijing Synchrotron Radiation Facility (BSRF). Two possible conformations of the response regulator proteins, compact and incompact conformations, have been represented by the known crystallographic structures. And theoretical solution scattering curves of the two possible conformations were calculated and fitted to the experimental scattering curve of Dr-rrA, respectively. The result indicates that the solution conformation of the response regulator proteins is inclined to the compact one, which is in agreement with the result of biochemical experiments.     

Pr1-x Srx MnO3体系中O1s2p2p俄歇过程特性研究

对于组份为x=0.0和x=0.3的巨磁电阻锰氧化物Pr_1-x Sr_x MnO₃(PSMO)体系在OK阈值,Mn L_2,3边的区域内进行了O1s2p2p俄歇谱随光子能量变化的实验研究.实验结果显示O1s2p2p俄歇峰发生分裂并且可将其拟合为3个子峰.PSMO在OK阈值或Mn L_2,3边以下进行激发时,其俄歇峰3个子峰的相对强度基本保持恒定,然而反映终态效应特性的总强度却有起伏发生.这一状况在Mn L_2,3边以上激发时表现更为显著,即组份为x=0.3的总强度为x=0.0的4倍.对这些现象在共价键图     

Investigation of the topological shape of bovine serum albumin in solution by small-angle x-ray scattering at Beijing synchrotron radiation facility

This paper reports that at a newly constructed small-angle x-ray scattering station of Beijing Synchrotron Radia- tion Facility, the topological shape of ligand-free bovine serum albumin in solution has been investigated. An appropriate scattering curve is obtained and the calculated value of the gyration radius is 31.2~=t=0.25 ~_ （11=0.1 nm） which is co- incident with other ones＇ results. It finds that the low-resolution structure models obtained by making use of ab initio reconstruction methods are fitting the crystal structure of human serum albumin very well. All of these results perform the potential of the beamline to apply to structural biology studies. The characteristics, the defects, and the improving measures of the station in future are also discussed.     

钙钛矿型(Pbnm)化合物在高压下的结构变化

ABX₃型钙钛矿,最常见的结构为斜方晶系Pbnm,在高压下的结构变化具有多样性.本文简要介绍了3个参量(t,V_A/V_B,E_tot),描述ABX₃型钙钛矿结构的稳定性,全面总结了应用这3个参量建立的高压下钙钛矿结构(Pbnm)变化模型,基中有些模型对所有的钙钛矿结构都适合.通过举例,运用不同的模型对CaTiO₃(Pbnm)在高压下的结构变化进行综合分析,定性地得出随着压力的增加其结构的对称性应降低.     

Construction and Photoluminescence Properties of Zn(Ⅱ)/Cd(Ⅱ) Complexes with 4-Amino-3,5-propyl-1,2,4-triazole Ligand

Reaction of ZnCl2 and 4-amino-3,5-propyl-1,2,4-triazole(dpatrz) or CdCl2, NaN3 and dpatrz, in aqueous solution at room temperature yields two neutral clusters: a dinuclear complex [Zn2(dpatrz)2Cl4](I) and a linear trinuclear complex, [Cd3(dpatrz)4(N3)2Cl4](Ⅱ). Both complexes have been characterized by X-ray single-crystal diffraction, powder XRD, IR, elemental analysis, TG and fluorescence analysis. Complex I crystallizes in orthorhombic, space group Pbca with a = 11.865(2), b = 14.464(3), c = 15.985(3) , V = 2743.4(9) 3, Z = 4, C16H32N8Cl4Zn2, Mr = 609.4, Dc = 1.475 g·cm3, μ = 2.16 mm-1, F(000) = 1248, GOOF = 1.091, the final R = 0.0295 and wR = 0.0665 for 1999 observed reflections(I 2σ(I)). Complex Ⅱ crystallizes in monoclinic, space group P21/c with a = 11.408(2), b = 15.211(3), c = 18.152(6) , β = 123.75(2)o, V = 2619.1(1) 3, Z = 2, C32H64N22Cl4Cd3, Mr = 1236.05, Dc = 1.567 g·cm3, μ = 1.46 mm-1, F(000) = 1244, GOOF = 1.042, the final R = 0.0444 and wR = 0.0913 for 3466 observed reflections(I 2σ(I)). The analysis of X-ray revealed that both structures lie about the inversion centers: complex I adopts two μ1,2-triazole bridges linking two Zn(Ⅱ) ions and Ⅱ forms a linear trinuclear structure with four μ1,2-triazoles and two μ1,1-N3- bridging modes. There are different coordinated geometries for three Cd(Ⅱ) ions in Ⅱ: one is coordinated with an octahedral environment, and the other two are distorted tetragonal pyramids(τ = 0.34). The hydrogen bonds of C–H···Cl and N–H···Cl lead to the discretes into a 3D supramolecular network in both compounds. The thermal stabilities and photoluminescence behaviors of them were also studied.