油柑果超氧化物歧化酶的化学修饰及其性质的研究

从油柑果中提取SOD[Superoxide dismutase(EC1,15,1,1,)],用山梨醇月桂酸酯（Sorbitol laurate)进行化学修饰,得到SL－SOD。比活力为4200u/mg。交联葡聚糖凝胶层析测分子量为38KD,紫外区最大吸收峰是258nm,修饰后SOD对温度和PH的稳定性均有增强。在某些低浓度的有机介质中活性比在水中高。修饰SOD的半衰期为14h,有效保存期为43d。几乎无免疫原性。     

聚乙二醇修饰超氧化物歧化酶的初步研究

目的:对玉米超氧化物歧化酶(SOD)进行共价修饰,以提高其稳定性.方法:以分子量为6000Da的活化聚乙二醇(PEG)为修饰剂,对玉米超氧化物歧化酶(SOD)进行共价修饰,并确定最佳反应条件.将天然SOD与PEG-SOD分别进行热稳定性、酸碱稳定性及抗蛋白酶稳定性的比较实验.结果:在最佳反应时间10h、最佳反应温度4℃时PEG与SOD反应获得的PEG-SOD比天然SOD在热、酸、碱及抗酶解三方面的稳定性均有不同程度的提高.结论:玉米超氧化物歧化酶经PEG修饰后稳定性显著提高.     

甘油包埋绿豆SOD的稳定性研究

用不同浓度的甘油包埋绿豆(Phczeolus rodiatus L.)超氧化物岐化酶(Superoxide dismutase,SOD),对不同条件下制备的甘油SOD的稳定性进行评估.结果表明:甘油包埋绿豆SOD的稳定性受甘油浓度影响明显,12.5%～25%为最适甘油浓度.在10℃、pH 6.8、搅拌速度1000 r min-1.条件下包埋的甘油SOD在55℃的平均半衰期为25.1 d,为非包埋SOD的5.1倍.甘油浓度为25%,温度分别为5℃、10℃、25℃、45℃条件下,pH 3.8中包埋的绿豆SOD耐酸性较好,pH 8.9下包埋的绿豆SOD的抗碱能力较强.在包埋过程中添加一定浓度的Zn2 、Cu2 、Fe2 有利于其热稳定性的提高.甘油包埋SOD对一些常见的化妆品添加剂也有一定的抗性.由此可见,甘油包埋技术可望作为一项有应用前景的SOD活性保持新技术,有利于极端温度和极端pH条件下的SOD的应用.     

牛血清白蛋白对超氧化物歧化酶的化学修饰

目的：通过化学修饰提高超氧化歧化酶（SOD）的稳定性,考察金属离子在不同浓度下对SOD活性的影响。方法：用戊二醛作为交联剂,用牛血清白蛋白（BSA）将牛红细胞超氧化物歧化酶进行化学修饰,得到SOD的修饰酶。对比研究三种SOD：修饰酶,混合酶及天然酶的理化性质。结果：修饰酶等电点降低,对温度、pH的稳定性较天然酶有很大提高,对胰蛋白酶和胃蛋白酶也表现出很强的耐水解性。二价离子Mg^2 、Mn^2 对天种SOD活力均有不同程度的抵制作用,Ca^2 、Zn^2 、Cu^2 对修饰酶活力有激活作用,一价离子K^ 对三种OSD活力均无明显影响.结论:修饰酶较天然酶的稳定性有很大的提高,加入Ca^2 、Zn^2 、Cu^2 可提高修饰酶的活力。     

酰化人红细胞超氧化物歧化酶稳定性的研究

用月桂酸对人红细胞超氧化物歧化酶进行化学修饰处到酰化ｈ－ＳＯＤ,并对Ａｃ－ｈＳＯＤ和ｈ－ＳＯＤ的稳定性进行了比较。结果表明：Ａｃ－ｈＳＯＤ活力为ｈ－ＳＯＤ的７２％,比活力为４０００Ｕ／ｍｇ,Ａｃ－ｈＳＯＤ的热稳定性,酸碱稳定性及抗蛋白酶水解能力均比天然酶提高。     

酰化人红细胞超氧化物歧化酶稳定性的研究

用月桂酸对人红细胞超氧化物歧化酶（ｈ－ＳＯＤ）进行化学修饰得到酰化ｈ－ＳＯＤ（Ａｃ－ｈＳＯＤ）,并对Ａｃ－ｈＳＯＤ和ｈ－ＳＯＤ的稳定性进行了比较。结果表明：Ａｃ－ｈＳＯＤ活力为ｈ－ＳＯＤ的７２％。比活力为４０００Ｕ／ｍｇ,Ａｃ－ｈＳＯＤ的热稳定性、酸碱稳定性及抗蛋白酶水解能力均比天然酶提高。     

月桂酸高含量重组油菜的商业栽培

美国Calgene公司4月4日宣布,向美国农业部(USDA)申请用基因重组技术开发的月桂酸高含量油菜的商业栽培。Calgene公司进行野外试验的是导入了月桂酸合成的关键酶——硫代酯酶基因的油菜(最近栽培的油菜品种)。这种油菜含有普通油菜所不含的月桂酸,油脂含量为40％。月桂酸是肥皂和化妆品等的原料。但目前只能从椰子和棕榈椰子中得到。     

He-Ne激光对金针菇SOD高产株的诱变效应

用He-Ne激光辐照诱金针茹（Flammulina Velutipes）的原生质体、菌丝体片段,分生孢子悬液,并进行初筛、复筛及突变株遗传稳定性研究。结果表明：采用原生质体进行诱变,其正突变率,单株SOD产量提高率,产SOD遗传稳定性均高于菌系体与分生孢子。激光诱变原生质体是获得金针茹SOD高产株的有效途径。     

活性氧所致超氧化物歧化酶疏水性的变化

用抗坏血酸-Fe(Ⅲ)和过氧化氢分别作用于铜锌超氧化物歧化酶(SOD),经疏水层析分离得到亲水型和疏水型SOD.用胰蛋白酶和胃蛋白酶分别作用于天然SOD,亲水型SOD及疏水型SOD,结果表明疏水型SOD较亲水型SOD及天然SOD易被降解,提示活性氧氧化修饰后的SOD对蛋白水解酶敏感性提高与其疏水性增高有关.     

月桂酸生物印迹对脂肪酶酯化活力的影响

生物印迹是改良酶学特性,扩大脂肪酶工业应用领域的新兴技术。本研究结合溶胶-凝胶脂肪酶固定化工艺,以甲基三甲氧基硅烷（MTMS）和四甲氧基硅烷（TMOS）为前驱体,月桂酸为印迹分子,考察了月桂酸生物印迹对脂肪酶PS酯化活力的影响。脂肪酶酯化活力测定及扫描电镜观察表明生物印迹能显著提高脂肪酶的活性及稳定性。印迹体系经正交试验优化获得的最优条件为：水和硅烷摩尔比（R）为12,聚乙二醇（PEG）加入量为120μl,月桂酸加入量为0.15mmol。在最优反应条件下,印迹酶相对于游离酶比活力提高了44.3倍,相对于未印迹固定化酶提高了2.4倍;印迹酶具有较好的热稳定性,在80℃下处理0.5h后,残余酶活分别为58%,而游离酶未检测到活性。     

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.