肿瘤细胞诱导分化剂HMBA对自旋标记物TEMPO与蛋白质结构的影响…

在将ＴＥＭＰＯ掺入肿瘤细胞用以研究化学诱导分化剂六亚甲基二乙酰胺诱导分化机理的实验中，观察到一种强的单峰波谱，ＴＥＭＰＯ掺入到蛋白质分子的内部可能形成了局部的高浓度，肿瘤细胞诱导分化剂ＨＭＢＡ在诱导浓度范围内可使一些蛋白质分子的构象发生变化，改变ＴＥＭＰＯ与蛋白质分子的结合。     

掺铒SiO_x的光致发光特性

利用分子束外延设备生长了掺铒ＳｉＯｘ，观察到铒掺入的同时Ｏ的掺入效率也得到提高．铒可以促进氧的掺入的原因是铒与氧在硅衬底表面反应，以络合物形式掺入硅中，从而提高了硅中氧的浓度．测量了铒在ＳｉＯｘ中的光致发光特性，结果表明掺铒的ＳｉＯｘ的发光强度从１８Ｋ到３００Ｋ仅下降了约１／２，这说明Ｅｒ掺在ＳｉＯｘ中是一种降低发光强度的温度淬灭效应的途径，最后讨论了温度淬灭的机制．     

单分子操纵与单分子生物物理

文章介绍了近年来发展起来的一些单分子操纵实验技术如光镊、磁镊、微针、斯托克斯拖曳技术，以及应用这些技术拉伸、旋转、解链DNA分子，从而研究其力学性质所取得的研究进展．各种蛋白质如T7 DNA聚合酶、拓扑异构酶，SWI／SNF染色质重建复合体、RNA聚合酶与DNA的作用在生化过程中十分重要，因此，文章也介绍了这些蛋白质与DNA在单分子的水平上相互作用所取得的研究进展．     

利用平面激光诱导荧光技术测量燃烧场内NO的浓度分布

 介绍了平面激光诱导荧光的原理及实验装置，利用可调谐OPO激光器，在甲烷 空气火焰及一些高能燃剂燃烧火焰中测得了NO分子在不同压力、不同燃烧时刻的系列荧光谱线及二维浓度分布，并给出实验结果分析。     

pH诱导牛血清白蛋白芳香氨基酸残基微环境变化的光谱分析

用荧光光谱和紫外吸收光谱研究了ｐＨ＝２．３～１１．３范围内牛血清白蛋白（ＢＳＡ）芳香氨基酸残基微环境的变化,以此推断蛋白质构象的变化,并讨论蛋白质表面疏水性变化的趋热。与中性环境相比,ｐＨ为２．３时,色氨酸微环境的疏水性增强,蛋白质局部表面疏水降低;ｐＨ为１１．３时,部分Ｐｈｅ残基微环境的极性增强,表明碱诱导蛋白质分子变性使蛋白质分子充分伸展,将更多疏水性氨基酸残基暴露于溶剂中。     

纳米生物技术及其应用

纳米技术的发展使人们可以观测到纳米量级的介观世界，可以直观地了解生物分子的形态和分子间的相互作用，甚至可以操纵生物大分子，得到不同结构的新的生物分子．运用纳米技术制作的纳米器件可以用作疾病诊断与治疗．由纳米量级的超微粒构成的纳米生物材料具有良好生物相容性和一些独特的纳米效应，主要表现为小尺寸效应和表面或界面效应．纳米生物材料与相同组成的微米材料存在非常显著的差异，体现出许多优异的性能和全新的功能．纳米微粒在癌症的监测、治疗，细胞和蛋白质的分离，基因治疗，靶向和缓释控药物等中都有着广泛的应用．     

掺铒SiOx的光致发光特性

利用分子束外延设备生长了掺铒SiO_x,观察到铒掺入的同时O的掺入效率也得到提高.铒可以促进氧的掺入的原因是铒与氧在硅衬底表面反应，以络合物形式掺入硅中，从而提高了硅中氧的浓度.测量了铒在SiO_x中的光致发光特性，结果表明掺铒的SiO_x的发光强度从18K到300K仅下降了约1/2，这说明Er掺在SiO_x中是一种降低发光强度的温度淬灭效应的途径，最后讨论了温度淬灭的机制. 关键词：     

Analysis of the LIF Spectroscopy of Nickel Hydride in 19000-21400 cm-1

采用放电溅射出的镍原子与甲醇气体在超声射流条件下产生NiH分子,获得了NiH分子在15000~21400 cm-1的激光诱导荧光激发谱．首次报道了NiH分子在19000~21400 cm-1的光谱．将观测到的24个谱带归属到7个不同的电子跃迁,并对每个谱带进行了转动分析．观测到了A、B、D、E、F和G态的高振动能级,得到了这些电子态的振动频率、非谐性常数、转动常数和平衡键长等较完整的光谱常数．并重新标识了一些谱带．     

蛋白质动力学理论研究中的计算机模拟方法

蛋白质是生物体中一种十分重要的高分子物质。蛋白质分子有着自身所特有的化学、物理结构;在溶液中蛋白质分子不仅自身不同部分间存在着相互作用,而且还与溶剂分子间发生着复杂的相互作用,这些都很大程度上影响到分子的结构和演变过程。为了对蛋白质分子进行模拟,很有必要建立适当的描述蛋白质分子结构的模型,引入合理的模型基元间的相互作用,并采用有效的方法进行模拟,本着贴近现实和方便模拟的原则,在本文中我们系统地总结了近年来蛋白质动力学及其物理特性,特别对其模型、势能及模拟方法进行了着重介绍。为了增加一些感性认识,文中还就实验分析、折叠的协作性、搜寻保守残基和动力学过程的熵效应和阻挫效应等几个专题进行了应用介绍。     

蛋白质动力学理论研究中的计算机模拟方法

蛋白质是生物体中一种十分重要的高分子物质。蛋白质分子有着自身所特有的化学、物理结构;在溶液中蛋白质分子不仅自身不同部分间存在着相互作用,而且还与溶剂分子间发生着复杂的相互作用,这些都很大程度上影响到分子的结构和演变过程。为了对蛋白质分子进行模拟,很有必要建立适当的描述蛋白质分子结构的模型,引入合理的模型基元间的相互作用,并采用有效的方法进行模拟,本着贴近现实和方便模拟的原则,在本文中我们系统地总结了近年来蛋白质动力学及其物理特性,特别对其模型、势能及模拟方法进行了着重介绍。为了增加一些感性认识,文中还就实验分析、折叠的协作性、搜寻保守残基和动力学过程的熵效应和阻挫效应等几个专题进行了应用介绍。     

Nitroxyl free radical binding to Si(1 0 0): a combined scanning tunneling microscopy and computational modeling study

The ultra-high vacuum scanning tunneling microscope (UHV-STM) was used to investigate the addition of the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical to the Si(1 0 0) surface. Room temperature studies performed on clean Si(1 0 0)-2 × 1 confirm the proposed binding of the unpaired valence electron associated with the singly occupied molecular orbital (SOMO) of the molecule with a Si dangling bond. A strong bias dependence in the topography of isolated molecules was observed in the range of −2.0 to +2.5 V. Semiempirical and density functional calculations of TEMPO bound to a three-dimer silicon cluster model yield occupied state density isosurfaces below the highest occupied (HOMO) and unoccupied state densities isosurfaces above the lowest unoccupied molecular orbital (LUMO) which trend in qualitative agreement with the bias dependent STM topography. Furthermore, the placement of TEMPO molecules on dangling bonds was controlled with atomic precision on the monohydride Si(1 0 0) surface via electron stimulated desorption of H, demonstrating the compatibility of nitroxyl free radical binding chemistries with nanopatterning techniques such as feedback controlled lithography.     

The molecular basis of myeloid malignancies

Myeloid malignancies consist of acute myeloid leukemia (AML), myelodysplastic syndromes (MDS) and myeloproliferative neoplasm (MPN). The latter two diseases have preleukemic features and frequently evolve to AML. As with solid tumors, multiple mutations are required for leukemogenesis. A decade ago, these gene alterations were subdivided into two categories: class I mutations stimulating cell growth or inhibiting apoptosis; and class II mutations that hamper differentiation of hematopoietic cells. In mouse models, class I mutations such as the Bcr-Abl fusion kinase induce MPN by themselves and some class II mutations such as Runx1 mutations induce MDS. Combinations of class I and class II mutations induce AML in a variety of mouse models. Thus, it was postulated that hematopoietic cells whose differentiation is blocked by class II mutations would autonomously proliferate with class I mutations leading to the development of leukemia. Recent progress in high-speed sequencing has enabled efficient identification of novel mutations in a variety of molecules including epigenetic factors, splicing factors, signaling molecules and proteins in the cohesin complex; most of these are not categorized as either class I or class II mutations. The functional consequences of these mutations are now being extensively investigated. In this article, we will review the molecular basis of hematological malignancies, focusing on mouse models and the interfaces between these models and clinical findings, and revisit the classical class I/II hypothesis.     

Viscosity Effect Study on Quenching of Photoinduced Excited Triplet Duroquinone by TEMPO

ABSTRACT

Quenching dynamics of excited quinone molecules are given much attention in photochemistry and biochemistry. In order to study the viscosity effect on the quenching of triplet excited state of duroquinone (³DQ?) by stable radical, 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO), this study measured chemically induced dynamic electron polarization (CIDEP) spectra and transient absorptive spectra in various solvents. The solvents used were ethylene glycol, 1,2-propanol and their mixtures with different ratio in volume. The Stern-Volmer plot was obtained form CIDEP spectra of photolysis of DQ with different TEMPO concentrations. Combining the slope of the Stern-Volmer plot with lifetime of ³DQ?, determined from the ³DQ? transient absorbance decay curve, the quenching rate constants of ³DQ? by TEMPO were calculated in each solvent. The results indicate that the quenching rate constant is viscosity-dependent, and that it decreases linearly with the increase in solvent viscosity in the range used in our experiment.     

傅里叶变换红外光谱法研究HL-60细胞的分化过程

利用傅里叶变换红外光谱法(FTIR)研究了人白血病细胞HL-60在全反式维甲酸(ATRA)作用下向粒细胞分化的过程。结果表明,分化后的HL-60细胞FTIR图谱发生了显著变化,体现在与蛋白质、脂类、核酸和多糖等生物大分子相关的特征性谱带上。细胞内脂类物质烃链增长,含量增加。指纹图谱区域(900～1 300 cm-1)的谱带随着分化进程呈现规律性的变化。其中,核酸含量相对增加,并在1 052和1 153 cm-1附近出现了新的谱峰,二阶导数谱进一步发现在1 022 cm-1处出现新峰,这说明蛋白糖基化,磷酸化以及核酸氢键加强作用在HL-60细胞分化的过程中起着重要作用。通过计算一些图谱参数,并与硝基四唑氮蓝(NBT)还原实验相比较,证明红外图谱的变化与分化程度成正相关。     

Negative differential resistance of TEMPO molecules on Si(1 1 1)

Negative differential resistance (NDR) has been observed for individual 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) molecules on Si(1 1 1) in ultra high vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) measurements at room temperature. NDR effects were observed exclusively at negative bias voltage using an n-type Si(1 1 1) sample. At 77 K no NDR effects were observed, but the I(V) curves were similar in shape to those recorded on bare Si(1 1 1) sites. TEMPO was observed to adsorb preferentially at corner adatom sites of the Si(1 1 1)-7 × 7 structure. Although the Si(1 1 1)-7 × 7 reconstruction was conserved, local defects were frequently observed in the vicinity of the TEMPO adsorbates.     

Magnetic behaviour of polyfluoroacridine-based organic molecular materials

The solid state magnetic properties of two new molecular organic materials based on polyfluoro- acridines functionalised with the 2,2,6,6-tetramethyl piperidine-1-oxyl radical (TEMPO) have been analyzed. After a first characterisation of the two materials by electron paramagnetic resonance and by X-ray diffraction, magnetisation measurements were performed from room temperature down to 2 K and the paramagnetic behaviour due to the unpaired spin on the radical TEMPO observed. Both compounds show some ferro-magnetic interactions down to 40 K, while at lower temperatures an antiferro-magnetic contribution switches on, possibly related to the reduction of intermolecular distances.     

光解杜醌/氢给体均相体系的CIDEP研究

以杜醌为光敏剂,用高时间分辨电子自旋共振 (TRESR)波谱仪研究了杜醌/乙二醇体系、杜醌/氮氧自由基/乙二醇体系的化学诱导动态电子自旋极化(CIDEP).实验表明,紫外激光照射下,在杜醌/乙二醇溶液中得到以三重态机理极化为主的中性杜半醌自由基DQH*和以碳为中心的乙二醇碳自由基R*(OH)2的极化信号,而加入氮氧自由基 TEMPO后,则只观测到极化的TEMPO的E+E/A极化谱,其产生机理属于以四重态为先驱的自由基-三重态对极化机理(QP-RTPM),结合极化强度的理论计算对该体系的极化形成过程进行了分析.     

Ultrasound exposure in the presence of hematoporphyrin induced loss of membrane integral proteins and inactivity of cell proliferation associated enzymes in sarcoma 180 cells in vitro

Ultrasonically induced effects of hematoporphyrin (HPD) on cell damage and membrane protein alteration of S180 isolated tumor cells in vitro were investigated, and the potential mechanisms of sonodynamic therapy (SDT) inhibiting tumor growth were discussed. Tumor cells suspended in air-saturated PBS (pH 7.2) were exposed to ultrasound at 1.8 MHz for up to 180 s in the presence and absence of HPD. The viability of cells was determined by a trypan blue exclusion test. To estimate the damage effects of SDT on plasma membrane of tumor cells primarily, membrane integral proteins (EGFR, Ras, Fas, FasL) and cell proliferation associated enzymes (adenylate cyclase and guanylate cyclase) were checked with immunochemical methods. The results indicated that the intensity threshold for ultrasonically induced cell damage at 1.8 MHz was 3 W/cm². At this condition, the expression of the integral proteins was obviously inhibited and the activity of the enzymes was decreased post ultrasound treatment in the presence of 20 μg/ml HPD. Loss of the membrane proteins and inactivity of AC and GC post SDT was time-dependent. This paper reveals SDT can cause the loss of tumor cell membrane integral proteins and inactivity of the enzymes associated with cell proliferation which might be attributed to a sonochemical activation mechanism. The mechanisms by that tumor growth is inhibited by SDT can be understood as that the growth signaling pathway is partially interdicted and the resistance of tumor cells to the specifically activated immune cells is weakened.     

TEMPO及其衍生物充放电过程中电子得失理论特性

在(U)B3LYP/6-31G(d,p)或6-31+G(d,p)基组水平上用密度泛函方法对2,2,6,6-四甲基哌啶-1-氧自由基(TEMPO)及其阳离子衍生物在充放电过程中的电子结构和相关性质进行了理论研究. 结果表明在充放电过程中取代基对物质的电子结构和相关性质变化起着重要作用. TEMPO得电子后以单线态存在形式更稳定而阳离子衍生物却以三线态存在形式更稳定. 对TEMPO而言,无论是充电过程还是放电过程对自由基端的N和O的电子特性都有很大影响;对阳离子衍生物而言,放电过程主要影响吡啶端而充电过程主要影响自由基端的变化. 溶剂作用对自由基端的某些键长与电荷分布具有一定影响. 另外,用TDDFT方法对TEMPO及衍生物的紫外吸收光谱进行了计算和模拟,结果与实验数据吻合.     

The Biarsenical Dye Lumio™ Exhibits a Reduced Ability to Specifically Detect Tetracysteine-Containing Proteins Within Live Cells

Investigating the localisation of proteins within live cells via fluorescence microscopy typically involves the fusion of the protein of interest to a large fluorescent protein such as green fluorescent protein (GFP). Alternate fluorescent labelling technologies such as the fluorescent biarsenical dye molecules (e.g. FlAsH, ReAsH) are preferable to the use of large fusion proteins in many respects and allow greater flexibility in terms of the location of the labelling site. We assessed the ability of the FlAsH-derived biarsenical dye molecule Lumio™ to label a range of tetracysteine containing proteins within live cells and report that although in some circumstances Lumio is capable of positively detecting such proteins, the sensitivity and specificity of labelling is significantly reduced, making the Lumio-labelling system unsuitable for the detection of a wide range of protein within live cells.