液相色谱Z值对溶菌酶分子构象变化的定量表征

目前, 研究蛋白分子的构象变化用得最多的是光谱法, 如荧光光谱、圆二色谱和核磁共振谱等[1]. 由于蛋白质分子构象变化与其在色谱中的保留行为直接相关[2], 所以色谱法也成为研究蛋白质分子构象变化的一种新方法[3]. 此外, 计量置换理论中的Z值也已被成功地用于表征生物大分子的构象变化[4]. 用Z值研究蛋白质分子构象变化的优点是可以使用不纯的样品, 这是因为在测定Z值的过程中会与其它组分相分离. 使用Z值还会对蛋白分子构象变化进行定量表征[5,6]. 本文以溶菌酶(Lys)为目标蛋白, 用色谱法[反相液相色谱(RPLC)和弱阳离子交换色谱(WCX)]系统地研究了Lys在不同变性(胍变非还原、脲变非还原、胍变还原和脲变还原)环境中因疏水性及电荷分布的不同对Lys分子构象变化的影响, 并用Z值进行了定量表征.     

Isolating Reactions at the Picoliter Scale: Parallel Control of Reaction Kinetics at the Liquid–Liquid Interface

Miniaturized liquid–liquid interfacial reactors offer enhanced surface area and rapid confinement of compounds of opposite solubility, yet they are unable to provide in situ reaction monitoring at a molecular level at the interface. A picoreactor operative at the liquid–liquid interface is described, comprising plasmonic colloidosomes containing Ag octahedra strategically assembled at the water‐in‐decane emulsion interface. The plasmonic colloidosomes isolate ultrasmall amounts of solutions (<200 pL), allowing parallel monitoring of multiple reactions simultaneously. Using the surface‐enhanced Raman spectroscopy (SERS) technique, in situ monitoring of the interfacial protonation of dimethyl yellow (p‐dimethylaminoazobenzene (DY)) is performed, revealing an apparent rate constant of 0.09 min^?1 for the first‐order reaction. The presence of isomeric products with similar physical properties is resolved, which would otherwise be indiscernible by other analytical methods.     

聚(L-γ-氯乙基谷氨酸酯)的合成与构象

聚（Ｌ－γ－谷氨酸酯）类化合物是近年来被广泛用于蛋白质模拟及构象［１］、药物载体［２］和液晶大分子研究［３］,并可能是具有特殊场效应［４］的一类合成多肽．特别是在光电材料领域,人们发现将光致变色基团接入聚Ｌ－谷氨酸酯肽链的侧基是得到此类新型光电材料的最有效方法之一［５］．由于聚Ｌ－γ－谷氨酸酯是一类具有强旋光性的蛋白质,对其进行适当的改性后将对特定的小分子对映体有识别作用［６］,如将氨基糖接入聚Ｌ－谷氨酸酯的侧链就可制得能分离糖对映体的分离膜［７］．因此,将聚Ｌ－谷氨酸酯的侧链功能化,从而进一步…     

西加毒素(CTX)的电子结构及构效关系研究

应用MNDO方法对CTX衍生物进行了量子化学计算 ,得到了它们的电子结构信息.根据构象分析研究了它们的空间结构.推测出它们的活性部位 ,探讨了与受体结合时的作用方式 ,讨论了结构 -活性关系 ,解释了活性差异的原因.研究结果表明该类化合物的D、E、F环和A环及其支链等部位的不饱和键对活性有重要影响     

计算烷烃异构体生成焓的新方法

基于作者提出的诱导极性叠加原理,设计了包括与诱导极性叠加总量要关的能量项的烷烃异构体的标准生成焓估算的新方法。与前人方法比较,它具有较高的计算精度,较少的参数,各参数物理意义明确,而且理论上可以推广到含多种杂原子的衍生物的标准生成焓的计算。     

Syntheses and structures of Ag(I) complexes containing 1,4-bis(4,5-dihydro-2-oxazolyl)benzene

The reactions of the polydentate ligand 1,4-bis(4,5-dihydro-2-oxazolyl)benzene (L) with AgX (X = CH₃COO⁻, ClO₄⁻ and CF₃SO₃⁻) afforded the complexes [Ag₂(L)(CH₃COO)₂]_∞ (1), [Ag₂(L)₃(ClO₄)₂]_∞ (2), and [Ag(L)(CF₃SO₃)]_∞ (3), whereas the reaction of L with Ag₂SO₄ in MeOH/H₂O system afforded {[Ag₂(L)₃(H₂O)₃][SO₄] · 9H₂O}_∞ (4). The EA and IR have been recorded and all the complexes have been structurally characterized by X-ray crystallography, confirming that complexes 1–4 are two-dimensional coordination polymeric frameworks. The bidentate L ligands in complexes 3 and 4 adopt both the syn and anti conformation and those in 1 and 2 adopt the anti conformation only. The anions CH₃CO₂⁻ in complex 1 bridge the Ag(I) atoms in η¹, η², μ₃-coordination mode forming a 1-D zig-zag –[Ag(CH₃COO)]_n– chains, while the anions ClO₄⁻, CF₃SO₃⁻ and SO₄²⁻ in complexes 2–4 are not coordinated to the Ag(I) atoms, but all of them play an important roles in linking cationic 2-D frameworks into 3-D supramolecular structures.     

Conformational study of the 1,2,3-propanetriol (glycerol) in the channel of the aquaglyceroporin GlpF

The X-ray structure of the aquaglyceroporin GlpF protein refined by Fu et al. [D. Fu, A. Libson, L.J.W. Miercke, C. Weitzman, P. Nollert, J. Krucinski, R.M. Stroud, Science 290 (2000) 481--486.] shows three glycerol molecules co-crystallized inside the channel. The conformations of these molecules have been used to study the relationship between conformation, energy balance and hydration in the hope that it will provide insight into the molecular transport mechanism in the channel. Initially, the position of the hydrogen atoms of the glycerol molecule in the three conformations was established. As the glycerol molecule progressively loses its hydration waters in its transport pathway inside the channel, the nature of the glycerol bonds changes: the geometry of the alkyl backbone adapts to the available space while the progressive dehydration is partially compensated by the formation of intramolecular hydrogen bonds. The nature of these hydrogen bonds has been established by DFT calculation of the rotation barriers of the hydroxyl groups. Finally, the influence of the intramolecular hydrogen bonds on the conformation of the alkyl backbone has been established by quantum calculations of potential energy surfaces by semi-empirical quantum calculations PM3/Zindo.     

苯甲酰基硫代苯甲酸-S-苯酯的双重磷光研究

在对不同取代的苯甲酰基硫代苯甲酸-S-苯酯的光物理性质进行研究时,发现其苯甲酰基在邻位时可观测到双磷光现象,本工作对这种现象的机理进行了研究,确定这种现象是由于溶剂的作用,使溶液中具有多种不同的构象体,不同异构体的磷光发射不同,其激发波长也不同,改变激发波长可观察到双重磷光现象。     

Arrival time distributions of product ions reveal isomeric ratio of deprotonated molecules in ion mobility–mass spectrometry of hyaluronan‐derived oligosaccharides

Hyaluronic acid is a naturally occurring linear polysaccharide with substantial medical potential. In this work, discrimination of tyramine‐based hyaluronan derivatives was accessed by ion mobility–mass spectrometry of deprotonated molecules and nuclear magnetic resonance spectroscopy. As the product ion mass spectra did not allow for direct isomer discrimination in mixture, the reductive labeling of oligosaccharides as well as stable isotope labeling was performed. The ion mobility separation of parent ions together with the characteristic fragmentation for reduced isomers providing unique product ions allowed us to identify isomers present in a mixture and determine their mutual isomeric ratio. The determination used simple recalculation of arrival time distribution areas of unique ions to areas of deprotonated molecules. Mass spectrometry data were confirmed by nuclear magnetic resonance spectroscopy. Copyright © 2015 John Wiley & Sons, Ltd.     

羰基铁催化黄樟油素、丁香酚异构化反应的研究——Ⅰ.异黄樟油素、异丁香酚的合成

本文报道了异黄樟油素、异丁香酚的新合成途径,即在羰基铁光催化下或多核羰基铁加热催化下,使黄樟油素、丁香酚异构化。其转化率几乎是定量的。反应产物经GC,GC/MC分析及UV,IR,NMR,折光率的鉴定,证明合成过程中发生了异构化反应,而且产物以反式异构体为主。