环十二肽溶液构象的二维核磁共振研究

利用二维核磁共振方法及距离几何计算研究了在片段组装法全新蛋白质合成中用作底座分子的环十二肽的溶液构象. 研究结果表明在环十二肽分子主链中包含四个转角结构,四个赖氨酸侧链均位于环的同一侧.环肽的构象为以环肽为模板组装四螺旋束分子提供了有利的条件     

2.1分辨率A1-(L-色氨酸)胰岛素晶体结构研究

本文对A1修饰色氨酸胰岛素进行了晶体学的深入研究。晶体的空间群为R3,晶胞参数:a_H=80.3,c_H=37.5。应用立体化学制约最小二乘法并结合差值Fourier图人工分析对2.1的结构模型进行了多次调整和精化,最终偏离因子R=O.195。独立区两个A1-(L-色氨酸)胰岛素分子A链N端的A1色氨酸残基在电子密度图上表现十分清晰,其中分子ⅠA1色氨酸残基侧链具有两种构象。本文从结构角度推断三方四锌胰岛素分子Ⅱ的结构是一种低活性构象存在于六聚体内。此外,对有关胰岛素结构与功能的一些问题进行了讨论。     

木瓜蛋白酶的量子化学研究——1.肽基和各种类型氨基酸侧链的分子静电势比较

本文计算了木瓜蛋白酶分子中肽基和各种不同类型、非极性、极性不带电荷和带电荷氨基酸侧链的abinitio从头计算分子静电势图,并讨论了某些常和酶催化活性中心有关的侧链如天冬酰氨、丝氨酸和组氨酸等的静电势分布特点。     

蛋白质的电子结构与活性关系——理论与计算方法

随着生物工程的发展,要求对蛋白质的电子结构与活性关系进行研究。而不加分割地对蛋白质作完整分子的量子化学计算,至今尚未见报导。其原因在于,未能找到合适的数值计算方法。本文报导了这方面的研究成果。假设一个蛋白质由N个氨基酸残基构成,其中有L对硫-硫键,每一个氨基酸残基有m_n个单元轨道,则整个蛋白质分子的分子轨道可以写成这些单元轨道的线性组合:     

胰岛素单体的结构特征及其运动方式

运用最小二乘叠合技术及图象显示技术对已测定的不同种属和不同晶型的胰岛素及各种胰岛素衍生物空间结构进行了广泛的构象比较.研究结果表明:二锌胰岛素分子Ⅰ更接近于天然单体的结构;二体内两个分子之间的构象差异发生在二体形成过程中,并在六体形成及六体堆积过程中完善和稳定;通过一些铰链肽A10,B4,B8,B24,B20及B23,胰岛素分子内各结构片段之间具有较灵活的相对运动,羧端残基可能移动大于10A;由于所处的环境不同,各残基侧链的运动性差别很大.     

N-烷基化聚对苯二甲酰对苯二胺梳状高分子中烷基侧链对刚性主链堆积行为的影响

基于聚对苯二甲酰对苯二胺(PPTA), 采用N-烷基化方法制备了系列PPTACns(烷基侧链碳原子数n=8, 10, 12, 14, 16, 18)刚性主链梳状高分子, 利用DSC, XRD和FTIR等方法研究了其主链堆积行为、 分子链构象及热性能等与烷基侧链长度及结晶特性之间的关系. XRD和DSC结果表明, 当烷基侧链碳原子数达到14时, 烷基侧链发生结晶. XRD结果显示, PPTACns具有层状结构, 烷基侧链长度对主链层间距影响显著. FTIR研究发现, 烷基侧链的聚集状态对PPTACns分子链的构象产生较大影响, 伴随着烷基侧链结晶的熔融, PPTACns的分子链构象发生显著改变. 烷基侧链处于熔融状态的PPTACns的ν_C=O和γ_C-H谱带峰位与烷基侧链不结晶的PPTACn接近.     

NaCl溶液中纤连蛋白在TiO_2表面吸附的动力学模拟

对NaCl水溶液环境中,纤连蛋白(FNIII_(10))分子在金红石型TiO_2 (110)表面的吸附行为进行了分子动力学模拟.根据模拟溶液各成分与TiO_2表面原子之间的径向分布函数、离子在水溶液中的扩散系数及FNIII10和离子的吸附构象等相关参数发现,分布于TiO_2表面的稳定双层水分子是固液界面的主要特征,FNIII10分子通过天冬氨酸残基侧链末端的羧基基团(COO~-)同表面Ti原子之间的强相互作用,结合赖氨酸残基侧链及位于FNIII_(10)始端的精氨酸残基N端的氨基基团(NH_3~+)与表面桥氧原子之间的氢键作用,牢固地吸附在TiO_2表面.溶液中吸附在TiO_2表面的Na~+可与羧基氧原子配合形成稳定的吸附构型,而分布在第二水层外侧的Cl-对纤连蛋白分子在TiO_2(110)表面的吸附点位基本无影响.     

蛋白质分子与配体结合过程构象变化的研究

蛋白质分子与配体的作用模式主要有直接的环区结合及铰链式结合两种方式。针对这两种不同的作用方式,我们提出采用不同的策略进行结合过程的构象研究。对于直接的环区结合模式,通过建立环区主链构象库,来实现蛋白质环区与配体的准柔性对接,并以链霉抗生物素蛋白体系为例对构象库建立的可行性进行了验证计算。对铰链结合方式,采用分步对接的方法进行计算,并具体应用于HIV蛋白酶与其小分子配体的结合过程。计算结果表明,这两种处理方法分别能较好地模拟不同类型的蛋白质与配体结合的的构象变化。     

聚合物链构象的研究 Ⅰ.1,2-聚丁二烯的构象分析

本文应用Flory的链分子统计理论研究1,2-聚丁二烯的链构象,选择固定键长和键角的分子模型,计算构象能,构成势能面图,并由势能面的构型积分,得到了表征1,2-聚丁二烯链构象特征的统计权重矩阵.     

聚合物链构象的研究I: 1,2-聚丁二烯的构象分析

本文应用Flory的链分子统计理论研究1,2-聚丁二烯的链构象,选择固定键长和键角的分子模型,计算构象能,构成势能面图,并由势能面的构型积分,得到了表征1,2-聚丁二烯链构象特征的统计权重矩阵.     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Synthesis of phenolic components of Grains of Paradise

Two vanilloids, (5E)-8-(4-hydroxy-3-methoxyphenyl)oct-5-en-4-one (1) and 4-[3-hydroxydecyl]-2-methoxyphenol (2), isolated from the dried seeds of Grains of Paradise (Aframomum melegueta), were synthesized; the latter compound was made as the S-enantiomer and the material derived from the seeds was found to be a 1:1.7 mixture of the R and S isomers. The synthetic route used should allow the preparation of analogs having extended alkyl chains and consequently different lipophilicity, and 3, a homolog of 2, was also prepared.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Study of hydration of two cements of different strengths

Main hydration products of two cement pastes, i.e. CSH-gel, portlandite (P) (and specific surface S) were studied by static heating, and by SEM, TEM and XRD, as a function of cement strength (C-33 and C-43) hydration time (th) and subsequent hydration in water vapour.Total change in mass on hydration and air drying, M_o, increased with strength of cement paste and with hydration time. Content of water escaping at 110 to 220°C, defined as water bound with low energy, mainly interlayer and hydrate water, was independent on cement strength but its content increased with (th). Content of chemically bound (zeolitic) water in CSH-gel, escaping at 220-400°C, was slightly dependent on strength and increased with (th). It was possibly derived from the dehydroxylation of CSH-gel and AFm phase. Portlandite water, escaping at 400-500°C, was independent on cement strength and was higher on longer hydration. Large P crystals were formed in the weaker cement paste C-33. Smaller crystals were formed in C-43 but they increased with (th). Carbonate formated on contact with air (calcite, vaterite and aragonite), decomposed in cement at 600-700^oC. It was high in pastes C-33(1 month) and C-43(1 month), i.e. 5.7 and 3.3%, respectively; it was less than 1% after 6 hydration months (low sensitivity to carbonation) in agreement with the XRD study showing carbonates in the air dry paste (1month), and its absence on prolonged hydration (6 months) and on acetone treatment. Water vapour treatment of (6 months) pastes or wetting-drying increased this sensitivity.Nanosized P-crystals, detected by TEM, could contribute to the cement strength; carbonate was observed on the rims of gel clusters.This revised version was published online in November 2005 with corrections to the Cover Date.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

恶臭嗅辨实验室建设探讨

针对恶臭测试的环境影响问题,提出了解决的实例方案,并对方案的要点及优缺点进行讨论,此方案在实际操作中具有较好的效果。     

Investigation of Kinetics of Solid-Phase Synthesis of Lithium Orthosilicate

The kinetics of the interaction between lithium carbonate and silica with various degrees of dispersion was investigated by TG and DTA methods. It was found that the utilization of pyrogenic silica with a specific surface area of about 300 m²g^-1 instead of aerosil with one of 175 m²g^-1 leads to an increase of the reaction rate between lithium carbonate and silica, which depends on the formation and growth of lithium orthosilicate crystals in the first stage, and is conditioned by the diffusion of lithium and oxygen ions through the lithium orthosilicate layer formed at temperatures above 800 K. This supposition is supported by the kinetic analysis results obtained with the use of the different models. The optimal regime of heating is recommended. This revised version was published online in July 2006 with corrections to the Cover Date.     

小环化合物中饱和碳质子化学位移的计算

小环化合物由于其张力、构型、构象和各向异性效应等原因,环碳上质子化学位移缺乏规律性,难以预测,对此作者曾提出一种近似算法。本文根据303种小环化合物中饱和碳质子的化学位移实验数据,将适于计算这类质子化学位移的公式表述为:     

解决能源问题的新途径--光解水制氢的研究

面对日益枯竭的能源危机,氢能是一种洁净、最有前景的替代能源。目前在各种制氢的方法中光催化分解水制氢的研究最多,光解水过程中催化剂最关键,本文对利用太阳能光解水的途径、提高光催化反应效率以及光催化剂的开发研究进行了综述。