兔子朊蛋白结构稳定性的分子动力学研究(英文)

朊蛋白病是一种能够对人类和动物带来致命影响,并具有高度传染性的神经退行性疾病.兔子是目前已经报道的哺乳类动物中对朊蛋白病免疫的少数几个物种之一.我们将分子动力学和操控式分子动力学模拟相结合,研究了兔子正常朊蛋白的结构稳定性;同时讨论了蛋白结构的收敛性及刚性分布,并揭示了兔子朊蛋白中关键二级结构的动力学以及受力各向异性特征,证实了兔子朊蛋白结构的稳定性特征.     

麋鹿朊蛋白结构稳定性的分子动力学研究

朊蛋白病是一种致命且具有高度传染性的神经退行性疾病.糜鹿是目前已经报道的哺乳类动物中较易发生朊蛋白病的物种之一.作者使用分子动力学和操控式分子动力学模拟相结合的方法对糜鹿正常朊蛋白的结构稳定性进行了研究.发现了麋鹿朊蛋白结构中的不稳定结构域分布以及热动力学性质,揭示了糜鹿朊蛋白稳定性的分子结构基础以及力学特征.     

肝素诱导人细胞型朊蛋白构象变化的光谱表征

粘多糖在朊病毒病中所发挥的作用目前仍存在争议.以肝素钠作为粘多糖的代表,通过共振光散射光谱、荧光光谱和圆二色光谱的变化研究了肝素钠与人重组细胞型朊蛋白(rhPrPC23-231)的相互作用.结果表明,肝素钠与朊蛋白相互作用后光散射和荧光信号均得到增强,并且使朊蛋白的荧光寿命有一定程度的延长.圆二色光谱表明肝素钠能诱导朊蛋白从富含α-螺旋的构象向富含β-折叠的构象转变.     

荧光和圆二色谱法用于低密度脂蛋白氧化的研究

氧化修饰低密度脂蛋白（oxidized low density lipoprotein,oxLDL）被认为是动脉硬化的关键致病因素。oxLDL的性能与其唯一的组成蛋白-载脂蛋白B-100（apoB-100）的二级结构即构象密切相关。荧光光谱和圆二色（circular dichroism,CD）光谱是研究蛋白质构象的有力手段,因此在oxLDL结构的研究中也有广泛的应用。本文综述了近年来荧光光谱和圆二色光谱在LDL氧化研究方面的应用, 并对今后的研究方向做了展望。     

荧光和圆二色光谱法用于低密度脂蛋白氧化的研究

氧化修饰低密度脂蛋白（oxidized low density lipoprotein,oxLDL）被认为是动脉硬化的关键致病因素。oxLDL的性能与其唯一的组成蛋白——载脂蛋白B-100（apoB-100）的二级结构即构象密切相关。荧光光谱和圆二色（CD）光谱是研究蛋白质构象的有力手段,因此在oxLDL结构的研究中也有广泛的应用。本文综述了近年来荧光光谱和圆二色光谱在LDL氧化研究方面的应用,并对今后的研究方向做了展望。     

多肽与朊蛋白相互作用研究

朊病毒病是一类累及多种动物和人类中枢神经系统退行性疾病,但至今针对这类疾病尚无有效的治疗方法.考虑到在180位的缬氨酸突变为异亮氨酸的180I突变蛋白的突变位点与朊蛋白181位的糖基化位点非常接近,其生物化学性质对朊病毒病的影响非常重要.本文针对180I突变蛋白的182-190段序列设计了KNFTK、KTDVE、EMMKE和EVVKK等四种αxyzβ型多肽.研究发现,四种多肽中只有EVVKK能稳定蛋白的构象,同时诱导β-折叠向α-螺旋的转变,而其他三种蛋白对180I的结构基本没有影响.该结论对于开发多肽药物并进一步用于临床治疗具有一定的借鉴作用.     

谷朊蛋白的改性及其作为纸张增强剂的性能

采用廉价可生物降解的小麦谷朊蛋白为原料,经过羟甲基化和阳离子化改性合成类似聚酰胺聚胺环氧氯丙烷(PPE)的纸张增强剂. 经改性后,谷朊蛋白带有氮杂环丁烷结构、表氯醇和环氧基团3种功能基团,可与纤维形成共价键,且能发生自身交联,在纤维周围形成三维交联网络结构,提高纸张干、湿强度. 通过单因素试验,研究了甲醛、甲酸、温度、反应时间和环氧氯丙烷5种反应因素对纸张强度的影响. 优化合成条件下制备改性谷朊蛋白可使纸张干抗张强度提高35%,湿强保留率达20%. 改性后谷朊蛋白显阳离子性,加入纸浆中,可使得浆料体系Zeta电位升高,改善浆料的留着率,明显提高纸张强度. 结果表明,经羟甲基化和环氧氯丙烷加成改性的谷朊蛋白可以作为纸张的干强剂和湿强剂.     

核酸适配子共轭金纳米粒子探针成像朊蛋白细胞内在化途径

将巯基修饰的核酸适配子(aptmer)偶联到金纳米粒子(AuNPs)表面,制备出朊蛋白特异性的Apt-AuNPs纳米光学探针,并成功应用到细胞表面朊蛋白的光散射成像和电子透射显微成像分析.通过对Apt-AuNPs探针进入细胞的途径及其在细胞内命运的进一步研究表明,窖蛋白介导的内吞作用可能是其进入细胞的一个重要途径.Apt-AuNPs纳米探针制备简单、成本低廉,可能被广泛应用于生物医学成像领域.     

阻断铜离子介导神经毒性的小分子抑制剂研究

过量的铜离子介导淀粉样蛋白异常聚集被认为是导致淀粉样蛋白变性病的主要因素之一. 基于淀粉样蛋白聚集机理及金属铜离子的氧化还原机理, 我们选用β-淀粉样蛋白Aβ1-40作为蛋白模型, 设计并合成出由硫代黄素 T衍生出来的小分子抑制剂. 该小分子抑制剂可以螯合淀粉样蛋白周围过量的一价铜离子, 阻止有害的氧化还原循环过程, 抑制活性氧物质的产生, 从而达到保护细胞的目的. 这为治疗铜离子介导的淀粉样蛋白错误折叠所造成的疾病提供了新的策略.     

多金属氧化物立方纳米晶体的可控合成及其与朊蛋白的特异性相互作用

研究表明,在有机小分子二甲基甲酰胺（DMF）的调控作用下Keggin型多金属氧化物在水溶液中形成规则的纳米立方体,随温度改变该纳米立方体转变为空心立方结构．该多金属氧化物纳米立方体可以与朊蛋白（PrP^c）相互作用,产生显著的光散射信号增强,且增强程度在3．36-840ng·mL^-1范围内与朊蛋白浓度呈线性关系．     

脑神经退行性疾病中的有机化学-朊病毒(疯牛病)中的蛋白物理有机化学和自由基化学

通过关于“普里昂”蛋白病毒疾病的已有临床、医学生理、免疫和化学等方面的现象，讨论了朊病毒当中的部分蛋白氧化损伤和蛋白自由基化学本质。     

Genetic algorithms as a tool for helix design – computational and experimental studies on prion protein helix 1

Summary Evolutionary computing is a general optimization mechanism successfully implemented for a variety of numeric problems in a variety of fields, including structural biology. We here present an evolutionary approach to optimize helix stability in peptides and proteins employing the AGADIR energy function for helix stability as scoring function. With the ability to apply masks determining positions, which are to remain constant or fixed to a certain class of amino acids, our algorithm is capable of developing stable helical scaffolds containing a wide variety of structural and functional amino acid patterns. The algorithm showed good convergence behaviour in all tested cases and can be parameterized in a wide variety of ways. We have applied our algorithm for the optimization of the stability of prion protein helix 1, a structural element of the prion protein which is thought to play a crucial role in the conformational transition from the cellular to the pathogenic form of the prion protein, and which therefore poses an interesting target for pharmacological as well as genetic engineering approaches to counter the as of yet uncurable prion diseases. NMR spectroscopic investigations of selected stabilizing and destabilizing mutations found by our algorithm could demonstrate its ability to create stabilized variants of secondary structure elements.     

Hydrogen/deuterium exchange mass spectrometry identifies two highly protected regions in recombinant full‐length prion protein amyloid fibrils

Understanding the structural basis that distinguishes the amyloid form of the prion protein from its monomeric homologue is of crucial importance to elucidate the mechanism of the lethal diseases related to this protein. Recently, an in vitro conversion system was established which reproduces the transition of recombinant prion protein PrP(23–230) from its native α‐helical rich form into an aggregated amyloid β‐sheet rich form with physicochemical properties reminiscent to those of the disease‐related isoform of the prion protein, PrP^Sc. To study the tertiary and quaternary structural organization within recombinant amyloid fibrils from mouse, mPrP(23–231)^βf; bovine, bPrP(23–230)^βf; and elk, ePrP(23–230)^βf; we utilized hydrogen/deuterium (H/D) exchange analyzed by matrix‐assisted laser desorption/ionization (MALDI) and nano‐electrospray (nano‐ESI) mass spectrometry. No significant differences were found by measuring the deuterium exchange kinetics of the aggregated fibrillar forms for mPrP(23–231)^βf, bPrP(23–230)^βf and ePrP(23–230)^βf, indicating a similar overall structural organization of the fibrils from all three species. Next, we characterized the solvent accessibility for the soluble and fibrillar forms of the mouse prion protein by hydrogen exchange, pepsin proteolysis and nano‐ESI ion trap mass spectrometry analysis. In its amyloid form, two highly protected regions of mPrP(23–231) comprising residues [24–98] and [182–212] were identified. The residues between the two highly protected stretches were found to be more solvent exposed, but less than in the soluble protein, and might therefore rather form part of a fibrillar interface. Copyright © 2009 John Wiley & Sons, Ltd.     

Chemistry and Molecular Biology of Transmissible Spongiform Encephalopathies

Prion diseases are currently in the spotlight. Among them, the Creutzfeldt–Jakob disease in humans, scrapie in sheep, and bovine spongiform encephalopathy, or mad cow disease, are most commonly known. The term “spongiform” refers to the characteristic appearance of the lesions found in affected brains. It is likely that prion diseases originate from a causative agent that replicates independently of nucleic acids. Current research assumes that a structural isoform of prion protein, the scrapie form PrP^Sc, is the responsible pathogen. The three-dimensional structure, but not the amino acid sequence of the isoform differs from that of the normal cellular isoform, PrP^c. According to a widely accepted hypothesis, the normal isoform of the protein is converted by an autocatalytic process into the scrapie form upon contact with the latter. This hypothesis has not yet been proven. However, considerable progress has been made in the last few years, which might provide answers to many open questions about prion diseases, the subject of this review.