The three-dimensional structure of trichosanthin refined at 2.7resolution

The three-dimensional structure of trichosanthin crystallizing in space group C2 has beenrefined at 2.7 resolution from a previously reported starting model at 3 resolution based on asolvent flattened map and the revised primary structure consisting of 247 amlno-acids.The finalR-factor is 19.2% with the root mean-square deviations of 0.018 from ideal bond lengths andof 2.2° from ideal bond angles.Trichosanthin molecule is composed of two domains,the largedomain consisting of 181 amino-acld residues starting from N-terminus and the small domain con-sisting of the rest of the amino-acid residues.The molecule contains eight α-helices,five β-sheetsmade of sixteen β-strands,and some reverse turns.It is noteworthy that some of the α-helicesand β-sheets show irregular hydrogen bonding patterns.Six of the thirteen residues absolutelyconserved in eleven ribosome-inactivating proteins are located in a cleft near the interface ofthe two domains and they are likely to be active sites.Three additional conservative residueslocated in the cleft region might make some functional contribution as well.     

Structures of Cytochrome b_5 Mutated at the Charged Surface-Residues and Their Interactions with Cytochrome c

ＩｎｔｒｏｄｕｃｔｉｏｎＭｉｃｒｏｓｏｍａｌｃｙｔｏｃｈｒｏｍｅｂ5(Ｃｙｔｂ5)ｉｓａｍｅｍｂｅｒｏｆｃｙｔｏｃｈｒｏｍｅｂ5ｆａｍｉｌｙ ,ａｎｄｉｔｓｅｒｖｅｓａｓａｎｅｌｅｃｔｒｏｎｃａｒｒｉｅｒｉｎａｓｅｒｉｅｓｏｆｅｌｅｃｔｒｏｎ ｔｒａｎｓｆｅｒｐｒｏｃｅｓｓｅｓｉｎｂｉｏｌｏｇｉｃａｌｓｙｓ ｔｅｍｓ .1 3 Ｃｙｔｂ5ｉｓａｍｅｍｂｒａｎｅｐｒｏｔｅｉｎｗｉｔｈＭｒ～ 16ｋＤａ ,ｃｏｎｓｉｓｔｉｎｇｏｆｔｗｏｄｏｍａｉｎｓ ,ｏｎｅｈｙｄｒｏｐｈｏｂｉｃｄｏｍａｉｎｗｈｉｃｈａｎｃｈｏｒｓｔｈ…     

催化裂解C2H2制备空心碳球

在高岭土负载的镍催化剂上,于850 ℃催化裂解乙炔制备了直径约500 nm 的空心碳球.用XRD、TEM、SEM和显微激光Raman光谱对所得的碳球及催化剂进行了表征,并初步探讨了反应机理.     

Boosting the Capacitive Performance of Cobalt(Ⅱ)Phthalocyanine by Non-peripheral Octamethyl Substitution for Supercapacitors

Main observation and conclusion In this paper,pristine cobalt(Ⅱ) phthalocyanine (CoPc) and non-peripheral octamethyl substituted CoPc (N-CoMe2Pc) are the focus ...     

The crystal and molecular structure of pentafluoropropionylbenzoylmethylene triphenylphosphorane

The crystals of pentafluoropropionylbenzoylmethylene triphenylphosphorane that bears two strongly electron-withdrawing groups in alkylidene moiety are monoclinic and its space group is C2/c, with a = 11.271(3)Å, b = 18.253(6)Å, c =23.938(7)Å, β = 91.09(2)°, z = 8. The X-ray diffraction intensity data were collected on a four-circle diffractometer. The structure has been solved by direct method and refined by block-diagonal least-squares method. The final R- index was 0.075 for 3146 independent observed reflexions. In this paper the structure of this ylide is compared with that of corresponding arsonium ylide previously reported. Both ylidic skeleton structures are planar with sp² hybridization. The bond length of P-C(1) is 1.748 (5)Å with bond order. 1.60 while the bond order of As-C(1) in the corresponding arsonium ylide is 1.46, indicating that the phosphonium ylide has a greater contribution of “ylene” structure to the overall structure. As a result the phosphonium ylide should be less reactive than the corresponding arsonium ylide. In both ylides, (he major delocalized canonical forms of negative charge are shown to be 3.     

Metal-Induced Planar Chirality of Soft-Bridged Binuclear Platinum(II) Complexes: 100 % Phosphorescence Quantum Yields,Chiral Self-Sorting,and Circularly Polarized Luminescence

Pt^II complexes have attracted a great deal of interest due to their rich phosphorescent properties. However, these square-planar Pt^II complexes are far more likely to encounter the problems of lack of metal-induced chirality and emission “aggregation-caused quenching”. Herein, soft-bridged binuclear Pt^II complexes bearing metal-induced planar chirality were synthesized and characterized. These soft bridging ligands with smaller conjugated system would help to not only improve solubility for synthesis and enantioseparation but also introduce point chirality from amino acid for highly efficient diastereoselectivity. Furthermore, the intramolecular Pt−Pt distances could be well regulated by soft bridging ligands, and consequently the phosphorescence quantum yield up to 100 % could be achieved by shortening intramolecular Pt−Pt distance for first time. These complexes can be used as emitters in highly efficient solution-processed organic light-emitting diodes.     

C2v对称性簇Ru2N2的理论计算

采用密度泛函(B3LYP)方法计算了Ru2的部分低能电子组态，得到Ru2基态的电子谱项为7Δu，平衡核间距re=0.228 nm，振动频率ωe=338 cm－1，离解能De=1.92 eV. 同时计算了具有C2v对称性的Ru2N2簇中氮的活化情况，得到了各个优化几何构型下的键参数和体系能量.计算结果表明，氮氮键的活化程度由Ru2对氮起反馈作用的轨道数目决定.一般来说，氮氮键活化越强，体系能量越高，在相同的活化程度下，自旋多重度高的体系较稳定.     

Molecular Modeling of Interactions of the Benzolactam-V8 Modulators with the Cys2 Domain of Protein Kinase Cδ

Molecular modeling of interactions of four 7- or 8-substituted benzolactam-V8 （BLV） molecules with the cys2 activator-binding domain of protein kinase C （PKCδ） was carried out using molecular docking program Autodock. The docked models reveal that the hydroxymethyl group at the C（5） atom of the eight-membered ring of each BLV is bound at the bottom of the binding groove of the cys2 domain of PKCδ The BLV molecules make hydrogen bonds and hydrophobic interactions with PKCδ, which are similar to those in the crystal structure of the cys2 domain of PKCδ in complex with phorbol 13-acetate. BLV-1 does not contain a long side chain that is hydrophobic and necessary for membrane insertion, so that it would not be a potent modulator of PKCδ. The other three BLV molecules have long side chains substituted at C（7） or C（8） atoms, and it was predicted, based on the docking results, that they had the PKCδ-binding affinity in the order of BLV-2〉BLV-4〉BLV-3, and BLV-2 would be a potent activator of PKCδ.     

Molecular modeling of rice Rubisco

Molecular model of rice Rubisco has been constructed by molecular modeling method on a computer graphics workstation using graphics software TOM-FRODO and QUANTA/CHARMm,based on the three-dimensional structure of spinach Rubisco.The molecular modeling was carried out in the following procedure:amino-acid sequence substitution;manual adjustment of the initial model;and energy minimization.The three-dimensional structure of the quaternary complex Rubisco-CO2·Mg2+·CABP of rice Rubisco has also been modeled and optimized using the program package XPLOR.The main-chain structure of rice Rubisco does not show obvious difference from that of spinach Rubisco,and the side-chains are located in the most favorable positions and orientations.The active-site structures are basically the same for the two species.The mutant Leu335→Arg of rice Rubisco has been designed using the graphics software TURBO-FRODO and the program package XPLOR.Energy computation suggests that this mutation might increase the carboxylation