Desheptapeptide (B24 B30) insulin (DHPI), a virtually inactive insulin analog, has been crystallized in space group P2\-12\-12\-1 with two DHPI molecules in an asymmetric unit. The orientations and positions of the mo...Desheptapeptide (B24 B30) insulin (DHPI), a virtually inactive insulin analog, has been crystallized in space group P2\-12\-12\-1 with two DHPI molecules in an asymmetric unit. The orientations and positions of the molecules were determined by molecular replacement, and a structural model was built at 0.3 nm resolution. The current model shows that the two DHPI monomers are related by a non crystallographic 2 fold axis, nearly parallel to the crystallographic c axis. This structural feature complicated the determination of the orientation of the local 2 fold axis, which was later confirmed by analysing the diffraction data of DHPI crystals.展开更多
Desheptapeptide (B24—30) insulin (abbreviated as DHPI), prepared by the removal of the C-terminal amino acids of the B chain of insulin using limited enzymatic method, is an inactive analog of insulin. It can be crys...Desheptapeptide (B24—30) insulin (abbreviated as DHPI), prepared by the removal of the C-terminal amino acids of the B chain of insulin using limited enzymatic method, is an inactive analog of insulin. It can be crystallized in 30% acetone at pH 5.7 in platelet form. DHPI occupied a special position in those analogs with the Ctermini of the B chain shortened. Considering that the solution of the crystal strue-展开更多
The structure-function relationship of insulin to be understood at three-dimensional level has already been a challenging problem since the elucidation of fine crystal structures of insulin. Of course, it is a better ...The structure-function relationship of insulin to be understood at three-dimensional level has already been a challenging problem since the elucidation of fine crystal structures of insulin. Of course, it is a better experimental approach to such a problem that certain insulin-receptor complexes were prepared and their structures were展开更多
Two new isostructural multi-metal beryllium borates, m^3 Li Na4Be4B10O24F（M = Sr（1）, Cd（2））, have been synthesized by spontaneous crystallization. The structures were verified by single-crystal X-ray crystallogr...Two new isostructural multi-metal beryllium borates, m^3 Li Na4Be4B10O24F（M = Sr（1）, Cd（2））, have been synthesized by spontaneous crystallization. The structures were verified by single-crystal X-ray crystallography. The compounds crystallize in the trigonal space group R 3, with a = b = 9.4645（1） A, c = 38.842（8） A, V = 3013.2（6） A3, Z = 6, F（000） = 2568, Dc = 3.005 g/cm^3, Mr = 908.9, R = 0.0327, w R = 0.0678, μ = 8.160 mm-1 for Sr3 Li Na4Be4B10O24F and a = b = 9.3019（8） A, c = 37.782（7） A, V = 2831.12（9） A3, Z = 6, F（000） = 2748, Dc = 3.459 g/cm^3, Mr = 983.24, R = 0.0158, w R = 0.0455, μ = 3.586 mm-1 for Cd3 Li Na4Be4B10O24F. The structures are characterized by an infinite two-dimensional [Be8B16O40F2]∞ double layer bridged by [B12O24] groups like a sandwich structure, while the cations reside in tunnels along different directions. UV-vis-IR diffuse reflectance spectroscopy demonstrates that their cut-off edges are below 200 nm. Thermal analysis shows that they melt incongruently and their melting points are around 740-770 ℃.展开更多
运用杂化密度泛函B3LYP方法,在6-31G*水平上优化得到了一种Mg _(12) B _(24)团簇的笼状稳定结构,其IR最强吸收峰位于205.23 cm^(-1),Raman谱的最强峰位于242.63 cm^(-1).Mg _(12) B _(24)团簇笼状结构中B原子主要是sp杂化轨道参与成键,M...运用杂化密度泛函B3LYP方法,在6-31G*水平上优化得到了一种Mg _(12) B _(24)团簇的笼状稳定结构,其IR最强吸收峰位于205.23 cm^(-1),Raman谱的最强峰位于242.63 cm^(-1).Mg _(12) B _(24)团簇笼状结构中B原子主要是sp杂化轨道参与成键,Mg原子主要是s轨道参与成键.团簇中B原子层堆积了大量的电子,表明MgB 2的超导作用主要发生在B原子层;B原子层电子存在较强的离域性,也为超导电性提供了条件;Mg原子起了提供电子的作用.展开更多
文摘Desheptapeptide (B24 B30) insulin (DHPI), a virtually inactive insulin analog, has been crystallized in space group P2\-12\-12\-1 with two DHPI molecules in an asymmetric unit. The orientations and positions of the molecules were determined by molecular replacement, and a structural model was built at 0.3 nm resolution. The current model shows that the two DHPI monomers are related by a non crystallographic 2 fold axis, nearly parallel to the crystallographic c axis. This structural feature complicated the determination of the orientation of the local 2 fold axis, which was later confirmed by analysing the diffraction data of DHPI crystals.
文摘Desheptapeptide (B24—30) insulin (abbreviated as DHPI), prepared by the removal of the C-terminal amino acids of the B chain of insulin using limited enzymatic method, is an inactive analog of insulin. It can be crystallized in 30% acetone at pH 5.7 in platelet form. DHPI occupied a special position in those analogs with the Ctermini of the B chain shortened. Considering that the solution of the crystal strue-
文摘The structure-function relationship of insulin to be understood at three-dimensional level has already been a challenging problem since the elucidation of fine crystal structures of insulin. Of course, it is a better experimental approach to such a problem that certain insulin-receptor complexes were prepared and their structures were
基金supported by the National Natural Science Foundation of China(No.50972149,61138004,51402316)the National Instrumentation Program(No.2012YQ120048)
文摘Two new isostructural multi-metal beryllium borates, m^3 Li Na4Be4B10O24F（M = Sr（1）, Cd（2））, have been synthesized by spontaneous crystallization. The structures were verified by single-crystal X-ray crystallography. The compounds crystallize in the trigonal space group R 3, with a = b = 9.4645（1） A, c = 38.842（8） A, V = 3013.2（6） A3, Z = 6, F（000） = 2568, Dc = 3.005 g/cm^3, Mr = 908.9, R = 0.0327, w R = 0.0678, μ = 8.160 mm-1 for Sr3 Li Na4Be4B10O24F and a = b = 9.3019（8） A, c = 37.782（7） A, V = 2831.12（9） A3, Z = 6, F（000） = 2748, Dc = 3.459 g/cm^3, Mr = 983.24, R = 0.0158, w R = 0.0455, μ = 3.586 mm-1 for Cd3 Li Na4Be4B10O24F. The structures are characterized by an infinite two-dimensional [Be8B16O40F2]∞ double layer bridged by [B12O24] groups like a sandwich structure, while the cations reside in tunnels along different directions. UV-vis-IR diffuse reflectance spectroscopy demonstrates that their cut-off edges are below 200 nm. Thermal analysis shows that they melt incongruently and their melting points are around 740-770 ℃.
文摘运用杂化密度泛函B3LYP方法,在6-31G*水平上优化得到了一种Mg _(12) B _(24)团簇的笼状稳定结构,其IR最强吸收峰位于205.23 cm^(-1),Raman谱的最强峰位于242.63 cm^(-1).Mg _(12) B _(24)团簇笼状结构中B原子主要是sp杂化轨道参与成键,Mg原子主要是s轨道参与成键.团簇中B原子层堆积了大量的电子,表明MgB 2的超导作用主要发生在B原子层;B原子层电子存在较强的离域性,也为超导电性提供了条件;Mg原子起了提供电子的作用.
