狗脊蕨凝集素的分离纯化与部分性质

狗脊蕨叶组织经磷酸缓冲液抽提,硫酸铵分级沉淀,DEAE-Sepharose(fast flow)离子交换层析和Sephadex G-100分子筛层析,获得具有凝集活性的狗脊蕨凝集素.用PAGE和SDS-PAGE检测均显示1条蛋白带,提示狗脊蕨凝集素分子只有一个亚基.Sephadex G-100层析和SDS-PAGE测得其相对分子质量在20 kD左右.该凝集素对红细胞有种属专一性,其凝集活性可被木糖、卵粘蛋白所抑制.狗脊蕨凝集素对热相当稳定,以100℃温度加热10 min仍保存部分凝集活性.凝集活性不依赖于金属离子Mg2 、Ca2 、Mn2 .它的中性糖含量为3.1%,Phe含量较高,His含量较低,不含Tyr和Pro.     

染病刺参凝集素的分离纯化与性质比较

目的：研究刺参免疫机制,探寻其发病机理。方法：刺参（Apost／chopusjapon／cus）经磷酸盐缓冲溶液抽提、20—75％硫酸铵分级沉淀、DEAE—SepharoseF．F．和SephadexG一100柱层析,得到刺参凝集素（A几）。结果：经SDS—PAGE显示单一条带,亚基相对其分子量为31000。分别提取感染Tenacibaculum属和Vibrionaks属两种刺参烂皮病病原菌的刺参凝集素,感染Temcibaculum属病菌刺参的凝集素产量较大,但凝集兔红细胞的作用均不被所测试的单糖和寡糖所抑制,而仅被牛甲状腺球蛋白所抑制。凝集兔红细胞的作用均不被二价金属离子Ca2＋、Mg2＋、Mn2＋、Zn2＋及EDTA所抑制。在pH4．0。10．14系列缓冲液中均有活性,其中在pH4．0—7．5时活性最大。该凝集活性在90℃加热30min后凝集活性仅损失50％。结论：推断菌株Tenac／bacu／um可诱导刺参体内产生大量的凝集素。     

棉花凝集素的纯化及性质研究

抗枯萎、抗黄萎病的棉种的浸取液,经硫酸铵分级,纤维素柱、亲和层析后,再经分子筛过滤,获得在ＰＡＧＥ、ＳＤＳ－ＰＡＧＥ或ＨＰＬＣ柱上均呈现单一蛋白带的棉花凝集素。该凝集素只凝集兔红细胞,对人Ａ、Ｂ或Ｏ型血细胞均不凝集,其凝集活性可被半乳糖或猪甲状腺球蛋白等所抑制。棉花凝集素在６５℃加热５ ｍ ｉｎ,即丧失全部凝集活性;它的凝集活性强烈地依赖于Ｃａ２＋ ;Ｍｎ２＋ 对活性也有促进作用,Ｍｇ２＋ 则无作用。经凝胶过滤或ＳＤＳ－ＰＡＧＥ测定,凝集素的分子量为６３０００,Ｎ－末端氨基酸为Ｖａｌ。凝集素含有１．５％ 的中性糖,是一种促有丝分裂原,细胞转化率为５０．３％ 。     

坛紫菜凝集素的糖结合专一性和细胞凝集作用

坛紫菜的磷酸盐缓冲液浸取液,经硫酸铵沉淀和DEAE－Sepharose,SephadexG-100二步层析纯化,获得纯化的坛紫菜凝集素（PHL）。该凝集素能与3种单糖（阿拉伯糖,半乳糖,木糖）及麦芽糖专一性结合,其中与麦芽糖结合最强。细胞凝集实验结果显示,PHL能凝集兔,绵羊及鸡红细胞而不能凝集鸭,鸽子及人血红细胞,PHL还能凝集海洋微藻－绿色巴夫藻和淡水微藻－蛋白核小球藻,它们的凝集活性与藻细胞密度有关。不同状态的细菌和酵母细胞对PHL反应不同,表明随着细胞状态的改变,细胞表面的凝集素受体也随之发生变化。     

短裙竹荪(Dityophora duplicata)凝集素纯化与生化性质

短裙竹荪子实体经生理盐水抽提、硫酸铵沉淀、DEAE Sepharose和SephadexG 10 0柱层析纯化得到短裙竹荪凝集素 (Dityophoraduplicata(Bosc)Fischerlectin) ,简称DDFL .DDFL经PAGE显示单一条带 ,SDS PAGE测得其亚基分子量为 2 2 3kD ,SephadexG 10 0凝胶过滤测得分子量为 4 5 3kD ,DDFL不含中性糖 ,IEF测得其等电点为 3 92 .该凝集素对供试的 4种血型人血和兔、小牛、鸭、鸡、鲫鱼以及青蛙血红细胞具有凝集作用 ,但不凝集鳖红细胞 .它还可以凝集小鼠脾脏淋巴细胞和小鼠S180 肉瘤细胞 ,对兔红细胞的凝集作用可被乳糖、棉子糖、半乳糖、α 甲基半乳糖、β 甲基半乳糖和N 乙酰半乳糖胺所抑制 .氨基酸组成分析表明 ,DDFL含有 17种氨基酸 ,其中天冬氨酸、丝氨酸、苯丙氨酸和丙氨酸含量较高 .经测定 ,其N末端为甘氨酸 .DDFL对热、酸和碱具有一定的稳定性 ,经 6 0℃处理 10min ,可保持较高的活性 ,在pH 4 0～ 9 0范围内较稳定 ,其凝血活性依赖于Mg2 + 和Ca2 + 二价阳离子 ,Mn2 + 和Zn2 + 则无影响 .DDFL对小鼠腹腔注射的半致死量为 70 6 3mg kg .     

龙须藤凝集素的分离纯化和性质

利用酸化处理的Sepharose 6B亲和柱从龙须藤（Bauhinia championii)种子中分离纯化出龙须藤凝集素（BCL）,其比活性比抽提液提高了57倍,活力回收率达63．3％。经Sphadex G-100测得BCL的分子量为64000,SDS－PAGE的结果表明BCL由两个相同的亚基组成,亚基分子量为32000,等电聚集凝胶电泳测得其等电点为4．70。BCL是一种糖蛋白,其中性糖含量为3．0％。N－乙酰－D－氨基半乳糖能强烈地抑制BCL对兔红细胞的凝集作用。     

棘托竹荪凝集素的纯化及其生化特性

棘托竹荪(Dictyophora echinovolvata Zang, Zheng et Hu)子实体经生理盐水抽提、硫酸铵沉淀、DEAE-Sepharose和Sephadex G-100柱层析纯化得到棘托竹荪凝集素(DEL).经PAGE显示单一条带,相对分子质量为38 000, 其亚基相对分子质量为18 900; 不含中性糖,IEF-PAGE测得其等电点为4.21.该凝集素对供试的4种血型人血和6种动物血的红细胞具有凝集作用,也能凝集小鼠淋巴细胞和小鼠S180肉瘤细胞,对兔红细胞的凝集作用可被乳糖和果糖所抑制.DEL含有15种氨基酸,其中天冬氨酸、谷氨酸、甘氨酸和缬氨酸含量较高; N-末端为丙氨酸.DEL对热不稳定,经50℃处理10 min,活性明显降低; 在pH 4.00～pH 10.14范围内较稳定; 其凝血活性依赖于Mn2 和Ca2 ,Mg2 和Zn2 则无影响.DEL对小鼠腹腔注射的半致死量为1 180 mg·kg-1.     

厚果鸡血藤凝集素的纯化及性质

从厚果鸡血藤（ＭｉｌｅｔｉａｐａｃｈｙｃａｒｐａＢｅｎｔｈ．）的种子中分离纯化出一种具强凝集活性和强促有丝分裂原的凝集素。种子经磨粉、浸取、硫酸铵分级、ＤＥＡＥＳｅｐｈａｒｏｓｅ离子交换和ＳｅｐｈａｄｅｘＧ１００分子筛层析,即可获得在ＰＡＧＥ和ＳＤＳＰＡＧＥ上均呈现单一蛋白染色带的凝集素纯品,分子筛层析测得分子量为４０７００,ＳＤＳＰＡＧＥ测得亚基分子量为１９８００;含有１７８％的中性糖。氨基酸组成分析表明,该凝集素富含Ａｓｐ、Ｇｌｕ、Ｔｈｒ、Ｓｅｒ和Ｌｅｕ,同时含有４个Ｔｒｐ,当凝集素浓度为０．４８μｇ／ｍＬ时,即可凝集兔红细胞;对人Ａ、Ｂ和Ｏ型血细胞都能发生凝集,故无血型专一性;其凝集兔红细胞的凝集活性,不能被常见糖类抑制,但可被甲状腺球蛋白、胃粘蛋白和卵粘蛋白所抑制;其凝集活性强烈地依赖于Ｃａ２＋的存在,但Ｍｇ２＋、Ｍｎ２＋、Ｚｎ２＋对其凝集活性全无促进作用;该凝集素是一种强促有丝分裂原,对人外围血中淋巴细胞的转化率高达８４３％,细胞分裂比率可达７８％。     

中国鲎凝集素的分离纯化及性质研究

 经N-乙酰氨基葡萄糖交联琼脂糖亲和层析及以交联琼脂糖介质的高效液相分子筛层析,从中国鲎细胞溶解物中分离纯化了一种凝集素,其活性比原料鲎试剂提高128倍。鲎凝集素SDS电泳时表现出分子量为69000,和72000的二个亚基。N-乙酰氨基葡萄糖、D-半乳糖,D-甘露糖及岩藻糖等对鲎凝集素凝集鸡红细胞的活性有显著抑制作用,加热60℃,10分钟可使凝集素活性基本丧失。CaCl_2为凝集素活性所必需。鲎凝集素与肺炎球菌C多糖有沉淀反应。     

孔石莼(Ulva pertusa)凝集素的分离纯化及性质的研究

为抑制肿瘤细胞增殖和防治有关病害提供基础理论依据 ,将孔石莼 (Ulva pertusa)经磷酸盐缓冲液抽提 ,2 0 %～ 75%硫酸铵分级沉淀 ,牛甲状腺球蛋白 - Sepharose4B亲和层析 ,可以从绿藻孔石莼中纯化出孔石莼凝集素 (UPL) ,在 PAGE上显示单一蛋白染色带 ,在等电聚焦电泳上显示单一蛋白染色带 ,其 p I为 8.40 .纯化后的 UPL的最大紫外吸收峰在 2 85nm,用 Sephadex G- 2 0 0分子筛层析测得其分子量为 1 1 0 4 7.该凝集素可以凝集人的 A、B、AB、O型红细胞 ,且凝集活性相同 ,在对人 (A、B、AB、O)兔、鲤、鲫的红细胞的凝集作用中 ,兔的凝集作用最强 .该凝集素凝集兔红细胞的作用不被 D-半乳糖、D-果糖、葡萄糖、蔗糖、甘露聚糖、γ球蛋白、卵清蛋白所抑制 ,仅被牛甲状腺球蛋白抑制 ,最小抑制浓度为 6.2 0 g/L.该凝集素在 p H4.0～ 1 0 .1 4范围内均有活性 ,但在p H6.50～ 9.51范围内活性较高 ,该凝集活性在 85℃加热 1 h,活力仍未改变 ,说明具有很强的耐热性 .     

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.