UDP-3-O-(R-羟基十四酰)-N-乙酰氨基葡萄糖脱乙酰基酶的表达、纯化及与ACHN-975复合物的X-射线衍射分析

目的以 UDP-3-O-(R-羟基十四酰)-N-乙酰氨基葡萄糖脱乙酰基酶(LpxC)-ACHN-975 晶体复合物结构为基础,研究小分子与靶蛋白的结合位点与方式,进而依据复合物结构设计该化合物,以获得活性强、毒性低的药物小分子。方法运用大肠杆菌表达系统对超嗜热菌(Aquifex aeolicus)来源的 AaLpxC 进行异源表达,采用 Zn^2+-NTA 亲和层析、Q-HP 强阴离子交换色谱和 Superose 12 分子排阻色谱对重组蛋白进行分离纯化,对 AaLpxC 进行结构生物学研究,采用蒸汽扩散-悬滴法进行结晶条件筛选以及优化。结果获得纯度在 90%以上的超嗜热菌来源的 AaLpxC,经过结晶条件的优化获得分辨率为 1.21 А(1 А= 1 × 10^-10 m)的 AaLpxC 与 ACHN-975 的复合物晶体的衍射数据,其晶胞参数为 a = 65.569 А,b = 65.569 А,c = 131.595 А,α= 90.000°,β= 90.000°,γ= 120.000°。结论 ACHN-975 与 AaLpxC 复合物晶体结构的获得有望对 ACHN-975 小分子结构优化及设计提供指导方向及重要依据。

微波湿热-循环冷冻对小麦淀粉结晶特性的影响

以小麦淀粉为原料,采用微波湿热-循环冷冻的方法制备抗性淀粉。利用扫描电镜(SEM)、红外光谱仪(IR)、X-衍射仪、差式扫描量热仪(DSC)研究了抗性淀粉的颗粒形貌、结晶结构、热力学性质。试验结果表明:在淀粉乳质量分数25%,微波功率700 W,微波时间2 min,循环冻融6次(-18℃冷冻4 h,解冻1 h为1次冻融处理),抗性淀粉得率为15.85%。扫描电镜显示抗性淀粉由原来光滑球形变为表面粗糙的不规则片层结构;X-射线衍射图谱显示抗性淀粉的结晶结构由原淀粉的A型转变为更加稳定的B+V型;红外图谱表明(1 045/1 022)cm^(-1)峰强度比值增大,抗性淀粉颗粒内有序度增加;DSC图谱表明在115℃由于直链淀粉晶体熔融时吸热而造成1个较大的吸热峰,其热焓值为2 231 J/g,与原淀粉相比明显增大,表明抗性淀粉因直链淀粉重结晶形成,淀粉抗酶解作用增强。

Determination of Structure and Polarity of Si C Single Crystal by X-Ray Diffraction Technique

Structure and polarity of the Si C single crystal have been analyzed with the four- circle X- ray diffraction method by a double- crystal diffractom eter.The hexagonal{ 10 15 } pole figure shows that this Si C sam ple has a6 H modification.The difference between the integrated intensities m easured byω scan in the triple- axis diffraction set- up finds some convincing evidence that the surface is either a Si- terminated face or C- terminated face.The experi- mental ratios of| F( 0 0 0 L) | 2 / | F( 0 0 0 L) | 2 are in good agreem entwith the calculated ones after the dispersion cor- rections to the atomic scattering factors( L=6 ,12 and18,respectively) .Thus,this m easurem ent technique is con- venient for the application of the materials with remarkable surface polarity.

Synthesis and Characterization of New Palladium（ll） Complexes Containing 4,5-dimethyl-2,2＇-bipyridine： X-ray Crystal Structure of Bis（4-methyl pyrdine）-4,5- dimethyl-2,2＇-bipyridine palladium （11） Perchlorate

New heteroleptic and homoleptic complexes of the type[Pd（4,5-dmbipy）C12], [Pd（4,5-dmbipy）L2], and [Pd（4,5-dimebipy）2]2＋ （L = Pyridine or 4-methylpyridine（4-picoline）, bipy = 2,2＇-bipyridine, and 4,5-dimebipy = 4,5-dimethyl-2,2＇-bipyridine） were synthesized and characterized by IH NMR and elemental analysis. The crystal structure of bis（4-methylpyridine）-4,5- dimethyl-2,2＇-bipyridinepalladium（II）perchlorate [Pd（4,5-dmbipy）（4-pic）2]（CIO4）2 was also determined by single crystal X-ray diffraction. This complex crystallized in the triclinic crystal system and space group PI with a = 9.562 （2）, b = 11.326 （4）, c = 15.0120 （10） A°; α = 70.940°, β= 77.60 （2）, γ= 67.86 （2） and z = 4. The Pd （II） in square planar environment showed a small distortion towards tetrahedral through one coordinated bipyridine ring twisting with respect to the other.

Photocycloaddition of (4-methyl-7-coumarinyl) Oxyacetic Acid Propanediol Diester and X-ray Crystal Structure of Product

The photocycloaddition of (4-methyl-7-coumarinyl) oxyacetic acid propanediol diester 1 (C_27H_24O_10) in chloroform produced a single product 2 characterized to be syn head-tail. Crystal structure of 2 has been determined by X-ray diffraction analysis. The crystal belongs to orthorhombic system, space group Pbca, with cell parameters a=10. 745(5), b= 13. 443(4), c=33. 358(9) A, V=4791 (5) A￣3, M_r=508. 49,Z= 8, D_c=1. 41 g/cm￣3, μ= 1. 015 cm￣-1, F(000)=1064. The final R=0. 065 for 1587 observed reflections. Compound 2 has a large ring resulted from [2+2] photocycloaddition. The four-member ring of 2 has poor coplanarity, the two diagonal atoms of four-member ring are above the least-squares plane, and another diagonal atom couple is below the least-squares plane, the deviations of two couples are approximately equal.

X-ray Study on the Ring-substituted Phthalocyanines:Crystal Structure of Metal Free 1,4,8,11,15,18,22,25-Octa-butyloxyphthalocyanine

The crystal structure of 1,4,8,11,15,18,22,25-octa-butyloxyphthalocyanine was determined by X-ray diffraction methods. The crystal is of triclinic, space group P 1 with a = 14.0780(3), b = 14.3480(4), c = 17.0090(2) A, α = 72.156(2), β = 86.193(2), r= 73.655(2)°, C64H82N8O8, Mr = 1091.38, Z = 2, V = 3137.5(1) A3, Dc= 1.155 g/cm3, F(000) = 1172, μ(MoKα) = 0.077 mm-1, the final R = 0.0787 and wR = 0.2240 for 5795 observed reflections with I ≥ 2σ(I). The steric congestion between the neighboring butyloxy groups distorts the core of phthalocyanine into a saddle shape conformation. In the crystal lattice, molecules overlap to each other with π-π interaction but the extent of overlap is different along the three axial directions.

Preparation, crystallization and preliminary X-ray diffraction analysis of PH1948, predicted RNA methyltransferase from Pyrococcus horikoshii

RNA methyltransferase is responsible for transferring methyl and resulting in methylation on the bases or ribose ring of RNA, which existed widely but mostly remains an open question. A recombinant protein PH1948 predicting RNA methyl- transferase from Pyrococcus horikoshii OT3 has been crystallized. The crystals of selenomethionyl PH1948 belong to space group C2, with unit-cell parameters a=207.0 ?, b=43.1 ?, c=118.2 ?, β=92.1°, and diffract X-rays to 2.2 ? resolution. The VM value was determined to be 2.8 ?3/Da, indicating the presence of four protein molecules in the asymmetric unit.

X-ray Structure of 1- (3' -Phenyl-4' -morpholinyl-2' 5' - dithiole-1' - ylidene)-3, 4-biscarboethoxy-2-thionaphthalene

The title compound (C28H27NO5S3, Mr= 553. 69) was prepared bythe reaction of a-thiobenzoylthioformmorholine with diethyl acetylene dicarboxylate.The crystal is monoclinic, space group P21/n with a= 9. 160(3), b= 17. 726(3), c=16. 602(3) A ; β= 100. 375(13)°; V=2651. 4(10) A3, Z=4, Dc= 1. 387 g/cm3, μ(MoKa) =0. 319 mm-1, F(000) =1160, R=0. 0428, wR(F2) =0. 0910 for 2438 observed reflections (I>2(I)). X-ray analysis reveals that interatomic distances for C(5)-C(6), C(13)-C(14) and C(21)-C(22) are 1. 331(4), 1. 351(4), 1. 344(4)A respectively, which show that they are normal C=C double bonds. All S-C bondlengths are similar to typical S-C single bonds (1. 75 - 1. 78 A ). The five-membered ring A (C(5) -C(6) -S(2)-C(13) -S(1) ) (Fig. 1) and six-membered ringB (C(14) -C(15) -C(20) -C(21)-C(22)-S(3) ) (Fig. 1) adopt the flat twist conformation. Furthermore, the morpholine ring adopts chair conformtion.

Nd(Phen)_2(NO_3)_3的合成及晶体结构(英文)

合成了一种新的稀土配合物Nd(Phen)2(NO3)3,化学式为C24H16N7NdO9,Mr=690.68,晶体属于单斜晶系,Cc空间群,晶胞参数:a=1.11975(17)nm,b=1.8073(3)nm,c=1.3095(2)nm,β=100.584(3)°,V=2.6051(7)nm3,Z=4,Dc=1.761g/cm3,F(000)=1364,μ=2.060mm-1,λ(MoKα)=0.071073nm,R=0.0187和wR=0.0300,数据显示配位多面体为一个变形的反四方棱柱配合物,钕的配位数为十配位,4个氮原子和6个氧原子参与配位,4个Nd—N键长在0.2584(4)nm到0.2652nm之间,6个Nd—O键长则在0.2496(3)nm到0.2603nm之间.

High-resolution 3D Structures Reveal the Biological Functions of Reoviruses

Viruses in the family Reoviridae are non-enveloped particles comprising a segmented double-stranded RNA genome surrounded by a two-layered or multi-layered icosahedral protein capsid.These viruses are classified into two sub-families based on their particle structural organization.Recent studies have focused on high-resolution three-dimensional structures of reovirus particles by using cryo-electron microscopy (cryo-EM) to approach the resolutions seen in X-ray crystallographic structures.The results of cryo-EM image reconstructions allow tracing of most of the protein side chains,and thus permit integration of structural and functional information into a coherent mechanism for reovirus assembly and entry.

Crystal Structure of 8β-Hydroxyeremophil-7(11)-ene-12,8α(4β,6α)-diolide

8β-hydroxyeremophil-7（11）-ene-12,8α（4β,6α）-diolide was isolated from the Ligularia intermedia and characterized by MS, multi NMR and X-ray single crystal diffraction. Its crystal structure was determined as in a orthorhombic type, with space group P212121 with a=6.8519（5）, b=10.7191（8）, c=18.5942（14） A, V=1365.67（18） A,^3 Z=4, and the calculated density is 1.354 mg/m^3. F（000）=592, μ=0.101 mm^-1.

Effect of rolling temperature on microstructure and texture of twin roll cast ZK60 magnesium alloy

Twin roll cast ZK60 alloy strip/sheet with final thickness of 0.5 mm was prepared, and effect of rolling temperature on microstructure and texture development was investigated using OM and XRD technique, microstructure and texture were measured on specimens subjected to rolling experiment at different rolling temperature, and macrotexture was also evaluated by X-ray diffraction method. In addition, the （1010）and （0002） pole figures were measured, and the tensile test was performed to reveal the influence of rolling temperature on mechanical properties. The results show that the microstrucmre of ZK60 alloy sheet consisted of fibrous structure with elongated grains, and shear bands along the rolling direction after warm rolling. Dynamic recrystallization could be found during the warm rolling process at rolling temperature 350℃ and above. And many fine recrystallized grain could be observed in the shear bands area. It is a little difficult to see the recrystallized grain in the sheet warm rolled at 300℃ because of higher density of shear bands. The warm rolled ZK60 alloy sheet exhibited strong （0002） pole texture, the intensity of （0002） pole figure decreases with the increasing of rolling temperature and the basal pole tilted slightly to the transverse direction after warm rolling.

Synthesis and Structural Characterization of [(C_2H_5)_4N][V^((V))O_2(OC_6H_3(OCH_3)CHNNCSNH_2)]·H_2O

The reaction of tetraethylammonium metavanadate, （Et4N）VO3, with isovanillin semithiocarbazone（VSTC）, HOC6H3（OCH3）CH=NNHCSNH2, in a mixed solvent of ethanol, water and DMSO yields the mononuclear dioxovanadate（V） complex, [（C2H5）4N][V（V）O2 （OC6H3- （OCH3）CHNNCSNH2）](H2O （C17H31N4O5SV, Mr = 454.5） and its single-crystal structure has been determined by X-ray diffraction. The crystal belongs to orthorhombic space group P212121 with unit cell parameters a = 12.940（3）, b= 15.414（3）, c = 10.703（2） ?, V = 2134.8（11） ?3, Z=4, Dcalc = 1.414 Kg/m3, ( = 0.597 mm-1, and F（000） = 960. The final agreement factors are R = 0.076 and Rw=0.096 for 1600 observed independent reflections with F ≥4.0(（F）. The structure revealed that the vanadium atom is bound to two terminal oxygen atoms and one tridentate donor ligand in a distorted square pyramidal arrangement. The sulphur-nitrogen-oxygen donor Schiff-base ligand in the thiol form rather than the thione form is coordinated to the vanadium via the mercapto sulphur, the (-nitrogen and the hydroxylate oxygen.

Synthesis and Crystal Structure of Methyl(7,7-Dimethyl-2-amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran-3-yl)Carboxylate

The title compound methyl (7,7-dimemyl-2-amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran-3-yl) carboxylate (C19H20ClNO4, Mr = 361.81) was synthesized and crystallized. The crystal belongs to triclinic, space group P 1 with a = 8.519(2), b = 10.346(2), c = 11.481(3) A, α = 108.16(1), β = 107.78(2), γ= 91.83(2)°, Z = 2, V = 906.5(3) A3, Dc = 1.326 g/cm3, μ(MoKα) = 0.234 mm-1, F(000) = 380, R = 0.0467 and wR = 0.1270 for 3142 observed reflections (I > 2σ(I)). X-ray analysis reveals that the C(7), C(8), C(9), O(1), C(10) and C(11) atoms form a six-membered ring which adopts a boat conformation. In the ring, the distances of C(8)-C(9) and C(10)-C(11) are 1.332(3) and 1.357(3) A, respectively, which indicates that they are C=C double bonds. Another six-membered ring (C(8)-C(9)-C(15)-C(14)-C(13)-C(12)) adopts the half-chair confonnation. In addition, there are intermolecular hydrogen bonds in the crystal structure.

Crystal structures and elastic properties of Ti(Cu,Pt)2 and Ti(Cu,Pt)3 phases

This paper focused on the crystal structures of two new ternary phases,Ti(Cu,Pt)2 and Ti(Cu,Pt)3,which were studied by X-ray powder diffraction data using Rietveld method.Electron probe microanalysis was used for sample composition examination.Elastic properties of these phases were further measured by nano-indentation,and meanwhile calculated with first-principle(FP)calculations.It is found that the crystal structure of Ti(Cu,Pt)2 is of orthorhombic cell space group Amm2(No.38)with structural prototype of VAu2.The resolved structure of Ti(Cu,Pt)3 is of tetragonal Al Pt3 type,belonging to the space group P4/mmm(No.123).The nano-indentation measurement and FP calculations show that the elastic modulus of Ti(Cu,Pt)2 increases firstly then decreases with Pt content,whereas that of Ti(Cu,Pt)3almost linearly increases with Pt content.

One-dimensional Zigzag Chain Coordination Polymer [Zn(μ-phth)(imi)_2]_∞ Bridged by ο-Phthalato

The reaction of zinc carbonate with o-phthalic acid and imidazole in an aqueous-alcohol solution led to the formation of colorless crystals of [Zn(-phth)(imi)2]∞. Single-crystal X-ray analysis has revealed that the complex crystallizes in a monoclinic system, space group Pn with a = 8.394(2), b = 9.976(3), c = 9.959(3) ? ?= 104.409(4)? V = 807.6(4) ?, Z = 2, C14H12N4O4Zn, Mr = 365.65, Dc = 1.504 g/cm3, ?= 1.544 mm-1, F(000) = 372, the final R = 0.0466 and wR = 0.1171 for 1834 reflections with I >2(I). The complex displays a zigzag infinite chain structure in which each zinc (Ⅱ) center is coordinated by two oxygen atoms and two nitrogen atoms to generate a ZnN2O2 distorted tetrahedral geometry. The neighboring zinc atoms are bridged by the o-phthalate ligand. Each chain is linked by hydrogen bonds with its neighbors to form a three-dimensional coordination polymer.

Preparation of Organic Semiconductor PTCDA and Studies on Its Crystal Structure and the Absorption Spectrum

Organic semiconductoe 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) has been synthetized with 1,8-naphthalic anhydride using chemical method.X-ray diffraction spectrum shows that it is monoclinic.Visible absorption spectrum shows that its gap band is 2.2 eV with singlet exciton bandwidth of 0.9 eV.

Synthesis and Crystal Structure of a New Imidazole Coordinated Octamolybdate Compound

The title compound (Himi)4[Mo8O26(imi)2]4H2O (imi = imidazole) 1 was synthe- sized by the reaction of H2MoO4 and imidazole in aqueous solution. Single-crystal X-ray analysis reveals that compound 1 is crystallized in the triclinic system, space group P with a = 10.6219(8), b = 10.7260(8), c = 11.3220(9) , a = 92.842(2), b =117.364(1), g = 101.655(1), C18H36Mo8N12- O30, Mr = 1668.11, V = 1106.8(2) 3, Z = 1, Dc = 2.503 g/cm3, F(000) = 804, m = 2.298 mm-1, the final R = 0.0714 and wR = 0.1651 for 3121 observed reflections with I > 2s(I). The X-ray crystal structure analysis suggests that compound 1 is built up by two imidazole ligands coordinated by the centrosymmetric octamolybdate anions, protonated imidazole cations and crystallization water molecules.

Sintering,crystallization and dielectric properties of CaO-B_2O_3-SiO_2 system glass ceramics

CaO-B203-SiO2 （CBS） glass powders are prepared by conventional glass melting method at different melting temperatures whose properties and microstructures are characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It is found that there are SiO2 and some unknown phases in CBS glass melting liquid from 1 300 ℃ to 1 500 ℃ and the amount of these phases decreases with the increase of the melting temperature. The CBS glass melted at 1 450 ℃ could be sintered from 830 ℃ to 930 ℃ and the bulk densities of the samples are all higher than 2.4 g/cm^3. From the points of the properties and energy conservation, the melting temperature of 1 450 ℃ is the optimal melting temperature. The glass ceramic sintered at 850 ℃ exhibits better dielectric properties： er=6.33, tan6=2.2×10^-3 at 10 GHz, and the major phases of the samples are CaSiO3, CaB2O4 and SiO2.

Effect of Crystallization Conditions on Polymorphic Diversity of Malic Acid RS-Racemate

Enantiomers （R （＋） and S（-））, RS-racemate mixture of enantiomers） of malic acid C4H605 have been （double compound） and （R ＋ S） -conglomerate （mechanical investigated by means of X-ray diffractometry and high tern- perature X-ray diffraction method. The RS-racemate was found to be able to form three polymorphic modifications, which we denominated as M1 （monoclinic, space group P21/c）, M2 （monoclinic, space group Cc）, and Tc （triclinic, space group P-l ）, the latter modification having been unknown before. Modification Tc was also described, and its X- ray diffraction characteristics, including interplanar spacings d, hkl indices, unit cell parameters, were defined. In addi- tion, X-ray diffraction characteristics for both reported earlier M1 and M2 monoclinic polymorphic modifications were measured with higher accuracy. The ability of RS-racemate to form one of the above three modifications （MI, M2, and Tc） or their mixtures containing various proportions and combinations of the components （M1 ＋ M2, M1 ＋ Tc, or M2 ＋ Tc） was found to depend on the type of crystallization medium （a melt, aqueous medium, ethanol or acetone solu- tion）, crystallization rate （from 2--3 minutes to 4 months）, and crystallization temperature. Heating S-enantiomer and M1 RS-racemate up to their respective melting points （100 ℃ and 124 ℃, correspondingly） only made them undergo thermal deformations, while heating （R ＋ S） -conglomerate in the temperature range of 96--110 ℃ resulted in its homogenization to form M2 RS-racemate, which, near the melting point （118 ℃）, namely, in the range of 112-116 ℃, was transformed into MI RS-racemate. Keywords： polvmorDhism; racemic, chiral