粪臭素对胰蛋白酶部分性质的影响

研究发现粪臭素对胰蛋白酶活性具有抑制作用。采用紫吸收法察到粪臭素使胰蛋白酶紫外吸收峰增强,采用荧光光谱法发现粪臭素对胰蛋白酶有很强的荧光淬灭作用。根据Stern-Volmer方程测得胰蛋白酶的表观猝灭常数Kq为2.72×1012L/mol.s。表明粪臭素对胰蛋白酶的荧光猝灭很可能是静态猝灭。     

高良姜素与牛血清白蛋白作用的光谱研究

采用荧光猝灭、同步荧光、三维荧光和圆二色谱,研究高良姜素与牛血清白蛋白(BSA)之间的相互作用。结果表明:高良姜素对BSA有较强的荧光猝灭作用,且为静态猝灭,并计算出不同温度下二者的结合常数(Ka)与结合位点数(n)分别为9.33×10~6L/mol、1.17(290.15 K),2.34×10~6L/mol、1.09(296.15 K),4.57×10~5L/mol、1.01(303.15 K),1.02×10~5L/mol、0.99(310.15 K)。由热力学参数确定它们之间的作用力主要是氢键和范德华力,利用竞争结合实验推断高良姜素的结合位点为BSA疏水空腔的SiteⅠ。同步荧光、三维荧光和圆二色谱显示高良姜素与BSA作用时更靠近色氨酸残基,使其周围的疏水性减弱,而对蛋白α-螺旋结构影响较小。     

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。     

荷叶中紫云英苷和牛血清白蛋白相互作用的光谱学研究

本文采用荧光光谱法、紫外光谱法研究在生理条件(pH=7.4)下荷叶中紫云英苷(AST)与牛血清白蛋白(BSA)的相互作用。结果表明AST可与BSA结合并通过静态猝灭作用机制对BSA内源性荧光进行猝灭。在温度为298K及308K时,测得其猝灭速率常数(Kq)分别为4.31×1013L/mol/s和3.72×1013L/mol/s;结合常数(Kd)分别为2.009×105L/mol和0.927×105L/mol;结合位点数(n)分别为0.943和0.893。依据298K时测定的反应自由能变(△G0=-30.25kJ/mol),反应焓变(△H0=-59.02kJ/mol)及反应熵变(△S0=-96.54J/mol/K),结果发现AST与BSA间的结合反应可自发进行且其作用力主要表现为氢键和范德华力。此外,根据Frster非辐射能量转移理论得到AST与BSA之间的结合距离(r)为4.13nm,表明非辐射能量可从BSA转移至AST。     

槐定碱与牛血清白蛋白的相互作用研究

在模拟动物体生理条件下,用荧光猝灭、荧光偏振和紫外-可见吸收光谱法研究了槐定碱与牛血清白蛋白(BSA)结合作用。荧光猝灭数据显示,槐定碱与BSA发生反应生成了新的复合物,属于静态荧光猝灭。求出了不同温度(19、25、31、37℃)下槐定碱与BSA作用的结合常数分别为1.219×106,1.164×106,1.110×106和1.057×106L/mol,由van’tHoff方程式计算槐定碱与BSA反应的热力学参数:焓变ΔH和熵变ΔS值分别为-5.97kJ/mol和96.11J/(mol.K),表明槐定碱与BSA间的作用力以静电引力为主。以华法林和布洛芬(分别为siteI和siteII探针)为标记药物研究槐定碱在BSA上的结合位点,结果表明,槐定碱结合在BSA疏水空腔的siteI位点。     

羧甲基化壳聚糖季铵盐与牛血清白蛋白的相互作用研究

应用荧光光谱研究了羧甲基化壳聚糖季铵盐(CMCQA)与牛血清白蛋白(BSA)的相互作用.研究表明:CMCQA对BSA内源性荧光猝灭机制属于CMCQA和BSA形成复合物所引起的静态猝灭.在室温下,二者的结合常数为2.45×104 L/mol,结合位点数为1.04.二者主要靠静电引力相互作用.     

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)。     

诺氟沙星与牛血清白蛋白相互作用的研究

用荧光光谱法研究诺氟沙星与牛血清白蛋白之间的结合作用,确定了诺氟沙星与牛血清白蛋白的荧光猝灭机制为静态猝灭。通过测定和计算不同温度下该结合反应的结合常数和结合位点数,并根据热力学方程求得了结合反应的热力学参数,讨论了两者问的主要作用力类型是范德华力和氢键。同时采用同步荧光技术考察了诺氟沙星对BSA构象的影响。并从荧光寿命进一步证明诺氟沙星与牛血清白蛋白的荧光猝灭机制为静态猝灭。     

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。     

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.     

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.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.