Effect of isomerization of amino acid residues on the structure of aquaporin

The effect of isomerization of amino acid residues on the structure and water permeability of aquaporin has been investigated. It was established that the equilibrium configuration of the model D isomer is energetically less favorable than that of its natural L isomer. It is shown that the model D isomer of aquaporin is waterproof.     

The Mean Isomer Degeneracy of the Wiener Index

The mean isomer degeneracy of the Wiener index was previously shown to become unboundedly large as n (the number of vertices of the molecular graphs of the isomers considered) increases. We here show that there is a high isomer degeneracy in the case of molecules of medium size, namely when n = 6 and n = 7.     

Copper(I) bromide complexes of two 15-memberd O2S2-macrocycles with different sulfur-to-sulfur separations: dimer and one-dimensional coordination polymer

Abstract

A comparative study on the exo-coordination-based networking of 15-membered O₂S₂-macrocycle isomers (L¹ and L²) induced by interdonor distances is reported. In copper(I) bromide complexation, the isomer L¹ incorporating a shorter sulfur-to-sulfur separation yielded a discrete dimer complex [(μ-Cu₂Br₂)(L¹)₂] (1) in which two macrocycles are bridged by a Cu₂Br₂ square cluster. While, the reaction of copper(I) bromide with the isomer L² incorporating a longer sulfur-to-sulfur separation afforded a double-stranded one-dimensional (1D) coordination polymer {[(μ₄-Cu₂Br₂)(L²)₂]·CH₂Cl₂}_n (2) as a kinetic product which converted to [(μ₄-Cu₂Br₂)(L²)₂]_n (3) with different 1D connectivity pattern as a thermodynamic product. The results indicate as examples of programmed self-assembly that the proposed interdonor distances and the ligand isomerism play decisive roles cooperatively in the topologies of the supramolecular products via different coordination modes.     

甲苯硝化产物的气相色谱快速分析

A simple, rapid and accurate method of quantitative analysis is described for the determination of nitrated products of toluene by GC on a capillary column(0. 26mm×32m) of OV- 275 with FID detector. Five ni-trotoluenes( o,m,p -nitrotoluenes;2,4-dinitrotoluene and 2,6-dinitrotoluene)were separated within 10min .     

三烷基膦－铂－氢配合物的合成及NMR研究

合成了配合物ｔｒａｎｓ－ＰｔＨＸＬ２（Ｌ＝ＰＢｕ３、ＰＰｒ３、Ｐｅｔ３；Ｘ＝Ｃｌ－、Ｂｒ－、Ｉ－、ＳＣＮ－、ＣＮ－），并进行了１ＨＮＭＲ研究。测得Ｐｔ－Ｈ键的１Ｈ在高场的化学位移δＨ＝－８～－２４ｐｐｍ；１Ｊ（Ｐｔ－Ｈ）＝８００～１５００Ｈｚ和２Ｊ（Ｐ－Ｈ）＝１３．０～１７．０Ｈｚ。鉴定了配合物的顺反异构和键合异构。研究了阴离子配体（Ｘ）及中性配体（Ｌ）对Ｐｔ－Ｈ键的δＨ、１Ｊ（Ｐｔ－Ｈ）及２Ｊ（Ｐ－Ｈ）的影响，Ｐｔ－Ｈ键长与Ｐｔ－ＨδＨ的关系。Ｐｔ－Ｈ化学位移与Ｐｔ－Ｈ的伸展振动频率呈线性关系。     

A New Synthetic Route to Diastereomerically Pure Cyclopropane-Phosphorus Derivatives Utilizing the Chiron 5-L-Men-thyloxy-3-bromo-2(5H)-furanone and Racemic Dialkyl α-Hydroxyalkanephosphonate

ＩｎｔｒｏｄｕｃｔｉｏｎＣｙｃｌｏｐｒｏｐａｎｅ ｃｏｎｔａｉｎｉｎｇｎａｔｕｒａｌａｎｄｎｏｎｎａｔｕｒａｌｐｒｏｄｕｃｔｓｈａｖｅｒｅｃｅｉｖｅｄｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎａｓｓｙｎｔｈｅｔｉｃｔａｒｇｅｔｓａｓｔｈｅｉｎｃｏｒｐｏｒａｔｉｏｎｏｆｔｈｅｒｉｇｉｄｉｆｉｅｄｃｙｃｌｏｐｒｏｐｙｌｍｏｔｉｆｉｎｔｏｂｉｏａｃｔｉｖｅａｎａｌｏｇｕｅｓｌｅａｄｔｏｃｏｎｆｏｒｍａｂｌｙｃｏｎ ｓｔｒａｉｎｅｄｍｏｌｅｃｕｌｅｓ .1,2 Ｓｕｃｈｍｏｄｉｆｉｃａｔｉｏｎｓａｒｅｅｘｐｅｃ…     

HPLC检定二氨基甲苯参考物质纯度的研究

应用高效液相色谱法研究分离2,6—、2,4—、2,3—和3,4—二氨基甲苯异构体的色谱系统条件和检定二氨基甲苯参考物质纯度的试验方法     

Reversed-phase high-performance liquid chromatographic behavior of peptide isomers including a D-amino acid

Summary The chromatographic behavior of ten peptide isomers was investigated using isocratic eluting with reversedphase high-performance liquid chromatography. These peptides are growth hormone releasing factor, consisting of 29 amino acid residues and its isomers where on amino acid residue in the sequence was replaced with the corresponding D-amino acid. Linear relationship was observed between the logarithm of the capacity factors of the isomers and the acetonitrile concentration in the mobile phase with correlation coefficients of 0.995–0.998. The regression coefficients were almost the same for all the isomers with a relative standard deviation of 5.3%. These results suggest that the chromatographic behavior of peptide isomers is also predictable from the solvophobic theory. The regression coefficient reflects the molecular weight and the Y-intercept represents the hydrophobicity of the isomer. The peptide isomers can be separated from one another, based on the differences in the hydrophobicity of each isomer.     

过氧锆杂多化合物的合成、表征及催化活性

过氧锆钨硅杂多化合物;异构体;环氧化反应;催化活性;过氧锆杂多化合物的合成、表征及催化活性