光谱法和分子对接研究二氢杨梅素与人血清白蛋白相互作用

运用光谱法和分子对接理论研究了二氢杨梅素(dihydromyricetin,DMY)与人血清白蛋白(Human serum albumin,HSA)的相互作用。结果表明,DMY有规律的使HSA内源荧光猝灭,其猝灭机制为两者形成复合物而引起的的静态猝灭;两者结合常数KA均大于105L/mol,结合位点数n接近于1。根据热力学参数判断,两者结合反应能自发进行,主要作用力类型为静电作用力。计算得到DMY与HSA的结合距离r为3.32 nm,表明两者结合过程发生了非辐射能量转移。同步荧光和三维光谱分析结果显示,DMY使HSA的构象发生了一定程度的改变。位点竞争实验和分子对接结果表明,DMY在HSA上的更倾向结合位于亚结构域IIA(Site I)。     

芦丁与胰蛋白酶相互作用的光谱性质研究

利用紫外光谱和荧光光谱研究了芦丁和胰蛋白酶的相互作用机制。结果表明,生理pH 7.40条件下芦丁使胰蛋白酶的紫外吸收峰增强,特征荧光峰淬灭。并利用荧光淬灭反应测得芦丁和胰蛋白酶之间结合常数KA=6.8786×104(mol/L)-1,结合位点数n=1.0173。     

喜树碱对胰α-淀粉酶部分性质的影响

喜树碱对胰α-淀粉酶有明显的抑制作用,其抑制类型为反竞争性抑制。利用紫外差光谱,研究发现喜树碱能改变胰α-淀粉酶的空间结构;利用荧光光谱研究了喜树碱与胰α-淀粉酶的相互作用,计算了二者的结合常数KA=2.78×106(mol/L)-1和结合位点数n=1.2477。其结果对喜树碱的进一步开发具有一定的指导意义。     

栀子苷和牛血清白蛋白相互作用研究(英文)

在模拟生理条件下,利用紫外和荧光光谱法研究栀子苷和牛血清白蛋白相互作用。通过Stern-Volmer方程和Lineweaver-Burk考察栀子苷对牛血清白蛋白内源性荧光的猝灭机制,分别在298 K、310 K和322 K下利用结合常数和结合位点数计算反应体系的热力学参数。结果表明,当温度为298 K、302 K和322 K时,栀子苷对牛血清白蛋白的猝灭常数分别为4.632×104、3.515×104和3.575×104mol/L,结合常数KA分别为1.805×104、2.546×104和4.165×104,结合位点数分别为1.334、1.112和0.944,栀子苷对牛血清白蛋白的猝灭方式属于静态猝灭;热力学参数ΔG0,ΔH0,ΔS0,表明栀子苷与牛血清白蛋白结合作用力为静电引力,根据Frster非辐射共振能量转移理论,计算出栀子苷与牛血清白蛋白之间的结合距离为1.78 nm。     

厄他培南与人血清清蛋白体外相互作用的理化特性

研究新型碳青霉烯类抗菌素厄他培南（ertapenem, ERT）与人血清清蛋白（human serum albumin,HSA）的体外相互作用的物理化学特性。模拟生理条件下,计算机模拟技术结合荧光光谱和紫外光谱,研究ERT与HSA相互作用机制,荧光光谱实验中,Kq 值远大于2.0×1010 L·(mol·s)-1,ERT对HSA荧光猝灭的Stern-Volmer 曲线有良好的线性关系,表明ERT与HSA的相互作用表现为静态结合过程。HSA的最大发射波长发生轻微红移,说明HSA的微环境发生了改变。ERT与HSA的分子结合距离r值较小,说明发生能量转移现象。同步荧光技术解析出ERT对HSA的结构域微区构象产生影响,使色氨酸残基周围的微区构象及结合位域的疏水性发生改变。荧光相图技术解析出ERT与HSA相互反应呈线性,说明HSA构象型态的变迁为“二态”模型。HSA与ERT相互作用的热力学参数及分子模拟技术建立ERT-HSA结合模型,表明ERT与HSA的相互作用力主要是疏水作用力,兼有氢键作用力的存在。荧光偏振定量证明,HSA与ERT相互作用过程中生成了非共价复合物。光谱实验与计算机模拟结果基本一致,其结果可为研究ERT与HSA相互作用本质提供一定参考。     

胡椒碱分子键合人血清白蛋白位点的表征

利用荧光光谱法、紫外光谱法并结合计算机模拟技术在分子水平上研究了胡椒碱与人血清白蛋白(human serum albumin HSA)的键合作用.同步荧光及紫外光谱图表明,胡椒碱对HSA微环境有影响.位点竞争试验证明,胡椒碱分子键合在HSA的位点Ⅱ区.通过荧光光谱滴定数据求得不同温度下(300K 310K和318 K)药物与蛋白相互作用的结合常数及结合位点数.分子模拟的结果显示了胡椒碱与HSA的键合区域和键合模式,表明药物与蛋白有较强的键合作用;维持药物与蛋白质的相互作用力主要是疏水用,兼有氢键(位于氨基酸残基Arg 257,Arg 222及Arg218位).通过实验数据计算得到的热力学参数(ΔH0与ΔS0的值分别为原33.11 kJ·mol-1和原18.90 J·mol原1·K-1)确定了胡椒碱与HSA分子的相互作用力类型主要为氢键兼范德华力.     

秋水仙碱与胰蛋白酶相互作用的光谱性质研究

采用紫外光谱法和荧光光谱法研究了秋水仙碱与牛胰蛋白酶的相互作用。观测到秋水仙碱使胰蛋白酶的特征荧光峰猝灭。SternVolmer猝灭曲线显示,秋水仙碱对胰蛋白酶的荧光猝灭机制属于静态猝灭,猝灭常数Kq为6.60×1012(mol/L)1·s1;秋水仙碱与胰蛋白酶的结合常数为1.06×104L·mol1,结合位点数为1,作用力类型主要为疏水作用力。     

壳聚糖钴与牛血清白蛋白相互作用的研究

采用紫外-可见吸收和荧光光谱,研究了壳聚糖钴与牛血清白蛋白(BSA)的相互作用。结果发现:随壳聚糖钴浓度的增加,BSA的紫外-可见吸收光谱表现增色效应和较小的蓝移;壳聚糖钴可以猝灭BSA的内源荧光,其猝灭机理属于静态猝灭。在室温下,壳聚糖钴与BSA的的结合常数KA为2.40×106。     

水溶性壳聚糖与牛血清白蛋白相互作用的研究

采用紫外和荧光光谱研究了水溶性壳聚糖(CS)与牛血清白蛋白(BSA)之间的相互作用。结果表明:随CS浓度的增加,BSA的紫外吸收光谱表现出明显的增色效应和较小的紫移;CS可以猝灭BSA的内源荧光,其猝灭机理是CS与BSA形成复合物的静态猝灭。并且测定了在不同温度下,该反应的结合常数KA分别为6.92×106(298 K),5.01×106(308 K),3.31×106(318 K),CS与BSA以摩尔比1∶1结合。同时采用同步荧光光谱法探讨了CS对BSA构象的影响。     

芹菜素抑制α-葡萄糖苷酶的分子机制研究

[目的]分析芹菜素对α-葡萄糖苷酶的抑制作用类型,并探讨其抑制的分子作用机制。[方法]采用Lineweaver-Burk双倒数方程,分析芹菜素对α-葡萄糖苷酶的抑制作用类型;荧光光谱和分子对接阐述芹菜素抑制α-葡萄糖苷酶的分子作用机制。[结果]芹菜素对α-葡萄糖苷酶的抑制类型为竞争型抑制,抑制常数Ki=12.08μg/m L。芹菜素和α-葡萄糖苷酶的结合导致酶分子的内在荧光静态猝灭,不同温度(298 K、304 K、310 K)条件下荧光猝灭常数KA分别为0.859 4×104、0.617 7×104、0.486 5×104L/mol。酶分子中Tyr158、Ser240、Pro312、Phe314和Asn415等氨基酸残基为芹菜素与其结合的重要活性位点,芹菜素的A环5-OH和7-OH、B环4'-OH结构对其抑制活性起到关键作用。[结论]芹菜素是α-葡萄糖苷酶的竞争性抑制剂,疏水作用力和氢键是其与酶分子间的主要作用力。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.