反胶束体系中维生素E的胆甾醇酯酶催化水解

目的 :探索反胶束体系中维生素E醋酸酯的酶促水解规律。方法 :以维生素E醋酸酯的水解产物α -生育酚的生成量为检测指标 ,考察温度、pH值、离子强度、酶浓度、表面活性剂浓度、体系含水量等反应条件对胆甾醇酯酶催化活性的影响。结果 :在卵磷脂 胆固醇 环己烷反胶束体系中 ,胆甾醇酯酶对维生素E醋酸酯具有催化活性。结论 :胆甾醇酯酶发挥水解活性的最佳反应条件如下 :温度为 38℃ ,体系pH值为 8.0 ,胆甾醇酯酶浓度为 1IU·mL- 1 ,牛磺胆酸钠浓度为 5 0mmol·L- 1 ,表面活性剂浓度为 0 .0 2mol·L- 1 ,含水量W0 为 10 .5。     

反胶束体系中脂肪酶催化合成生物柴油

本文采用了实验室自制的Candida sp.99-125脂肪酶, 研究了其在丁二酸二酯磺酸钠(AOT)反胶束体系中, 催化大豆色拉油合成生物柴油的新方法。考察了溶剂极性、AOT浓度、W0(水与表面活性剂质量比)、缓冲溶液pH值、温度等因素对脂肪酶催化合成生物柴油的影响。研究结果表明: AOT/异辛烷反胶束体系为Candida sp.99-125脂肪酶催化提供了较为合适的微环境, 在W0为11, 表面活性剂浓度为50 mmol/L, 温度为40℃, 缓冲液pH值为7的AOT/异辛烷反胶束体系中, 醇油摩尔比为3∶1, 摇床转速为180 r/min, 采用12h3次流加1 mol当量的甲醇, 单批最高酯转化率可以达到90%。     

非离子反胶束中木素过氧化物酶催化性能研究

木素过氧化物酶（LiP）在环己烷/Brij30/水反胶束体系中可体现催化活力,然而在水/醇/TritonX100/环己烷反胶束体系中却没有催化活力。对影响Brij30反胶束中LiP催化活力各主要因素进行了优化并测定了LiP在其中的时间稳定性;结果表明,20℃下,使LiP体现最佳活力的Brij30反胶束介质条件为：ω₀＝8.5,pH＝2.2,［Brij30］＝600mmol/L;在此条件下,LiP的半衰期可达到50h;与水介质相比,酶活力下降了,但稳定性却提高了。直链醇是TritonX100形成反胶束的必要组分,为揭示醇的作用,还考察了戊醇对Brij30 反胶束中LiP催化活力的影响,发现高浓度戊醇对LiP有失活作用。据此推测助表面活性剂醇可能是LiP在环己烷/TritonX100/戊醇/水反胶束中不能体现催化活力的主要原因。     

AOT/异辛烷反胶束萃取纯化胰蛋白酶及酶变性失活问题的解决

用反胶束技术分离纯化蛋白质,具有高选择性、易于大规模操作等优点,具有良好的工业应用前景。但是离子型表面活性剂形成的反胶束体系萃取蛋白质容易引起蛋白质的变性,这是由于离子型表面活性剂的强电荷作用所导致的。对用AOT/异辛烷反胶束体系从胰酶粗提物中萃取胰蛋白酶进行了研究,通过在反胶束相加入乙醇,解决了反胶束萃取蛋白质时蛋白质变性失活的问题。并且由于乙醇的加入大大减少了分相的时间,简化了实验步骤,优化了实验方法,使此技术在工业上的大规模应用成为可能。通过优化各种实验条件,胰蛋白酶的前萃取率达到90%,反萃取率接近100%。最终得率为88%。纯化后的比活提高了5倍多,从300U/mg左右提高到了1800U/mg。     

反胶束萃取血红蛋白的研究

研究了ＣＴＡＢ－正辛醇－正庚烷交束溶液萃取牛血红蛋白（ｐＨｂ）时、ｐＨ值、表面活性剂浓度、助表面活性剂浓度、离子种类和离子强度、溶剂比以及蛋白质浓度等因素对萃取效果的影响,并以蛋白质分子与表面活性剂分子间的相互作用以及反胶束大空间阻碍作用上进行了解释。研究表明,水相ＰＨ值在１０．５￣１２．５之间,ＫＣ１浓度为０．１ｍｏｌ／ｌ,反胶束溶液中表面活性剂浓度为０．０２ｍｏｌ／ｌ,正辛醇与正庚烷之比为０．     

用乙醇消除AOT/异辛烷反胶束体系萃取过程中蛋白质的变性失活

用反胶束技术分离纯化蛋白质,具有高选择性、易于大规模操作等优点,具有良好的工业应用前景。但是离子型表面活性剂形成的反胶束体系萃取蛋白质容易引起蛋白质的变性,这是由于离子型表面活性剂的强电荷作用会导致蛋白质发生变性,从而在两相界面上产生沉淀。这也是离子型反胶束体系用于蛋白质萃取所存在的最大的困难。本文对用AOT/异辛烷反胶束体系从胰酶粗提物中萃取胰蛋白酶进行了研究,通过在反胶束相加入乙醇,解决了反胶束萃取蛋白质时使蛋白质变性失活的问题,并且大大减少了分相的时间。前萃取和反萃取之后的分相时间只需要10分钟左右,简化了实验步骤,优化了实验方法,在工业上的大规模应用成为可能。在本研究中,胰蛋白酶的前萃取率达到90%,反萃取率接近100%。最终得率为88%。纯化后的比活提高了5倍多,从300U/mg左右提高到了1800U/mg。     

反相胶束体系中辣根过氧化物酶的活力和动力学性质

本文系统研究辣根过氧化物酶在ＣＴＡＢ／Ｈ２Ｏ／ＣＨＣ．３－ｉｓｏｏｃｔａｎｅ（１∶１,Ｖ／Ｖ）反相胶束体系中的催化行为。在一定条件下酶反符合Ｍｉｃｈａｅｌｉｓ－Ｍｅｎｔｅｎ动力学。研究水含量、底物浓度、ＰＨ、温度、表面活性剂的浓度等对酶反应的影响,结果表明表面活性剂对酶表现非竞争性抑制作用,高浓度的过氧化氢抑制酶活,最适ＰＨ为７．０。在低水含量（Ｗ０＜５）的胶束体系中保温后,酶的活力发生不可逆的改     

氯化三辛基甲胺/氯仿/正丁醇反胶束萃取地木耳多糖

采用阳离子表面活性剂氯化三辛基甲胺(TOMAC)/氯仿/正丁醇反胶束体系萃取地木耳中的多糖。分析有机溶剂氯仿与助表面活性剂正丁醇比例、TOMAC浓度、多糖粗提液浓度、促溶剂盐酸胍浓度、盐离子种类和浓度对前萃取率的影响。结果表明:向0.5 mg/m L多糖粗提液中加入10 mmol/L盐酸胍(Gu HCl)和0.06 mol/L Na Cl,与等体积25 mmol/L TOMAC/氯仿-正丁醇(V∶V=3∶1)的反胶束体系混合,地木耳多糖前萃取率为53.21%;反萃时水相中Na Cl浓度为0.14 mol/L,盐酸胍浓度浓度为0.6 mol/L,在此条件下地木耳多糖反萃取率为93.2%。     

Tween类胶束体系中水杨酸铜络合物的SOD样活性

合成了水杨酸铜·乙醇络合物,提纯了Ｔｗｅｅｎ－２０、Ｔｗｅｅｎ－４０,Ｔｗｅｅｎ－６０．Ｔｗｅｅｎ－８０,并测定了它们在ｐＢ７．４的磷酸缓冲液中的ＣＭＣＯ。用Ｃｙｔ,ｃ－ＨＸ－ＸＯ法分别测定了水杨酸铜·乙醇络合物清除超氧阴离子自由基的活性,不同浓度的单纯表面活性剂对Ｏ２的影响,以及表面活性剂与水杨酸铜·乙醇络合物协同清除Ｏ２的作用。观察到在胶束体系中水杨酸铜·乙醇络合物的ＳＯＤ样活性明显高于缓冲液体系无表面活性剂时的ＳＯＤ样活性,表面活性剂本身也具有清除Ｏ２的功能。抗红细胞膜脂质过氧化实验也得到类似结果。     

超氧化物歧化酶活性测定的影响因素研究

以枯草芽孢杆菌黑色变种为材料．探讨了超氧化物歧化酶活性测定的影响因素。选用黄嘌呤氧化酶法测定SOD活性．考察细胞破碎条件、细胞保存形式、保存时间以及保存温度对SOD活性测定的影响。结论：细胞破碎条件、样品保存形式、保存时间、保存温度都对酶活性有较大影响。相对而言,保存温度和保存时间的影响比较大。SOD活性测定中以酶液形式低温保存,尽快检测活性为宜。     

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.