菜豆幼苗EPSP合成酶的分离纯化和它的部分性质

利用硫酸铵分级沉淀,Ｓｅｐｈｅｄｅｘ Ｇ－５０凝胶柱层析,ＦＰＬＣ Ｍｏｎｏ－Ｑ和磷酸纤维素离子层析法从菜豆幼苗中分离提纯了ＥＰＳＰ合成酶。该酶被纯化２９６１．６倍,比活性达到６２１９．４ｎｍｏｌｍｇ＾－１蛋白ｍｉｎ＾－１。该酶分子量经ＳＤＳ－ＰＡＧＥ检测为５１ｋＤ,等电点为ｐＨ５．７,酶促反应最适ｐＨ７．５,最适温度４５℃。６．２μｍｏｌ／Ｌ的除草剂草甘膦能抑制ＥＰＳＰ合成酶活性的５０％。     

胞外青霉素酰化酶的纯化及部分理化性质

巨大芽孢杆菌产胞外青霉素酰化酶发酵液经硫酸铵分级抽提及ＳｅｐｈａｄｅｘＧ－１００、羟基磷灰石、ＤＥＡＥ纤维素ＤＥ５２等层析步骤,提纯了青霉素酰化酶,得到电泳均一的酶制剂。纯酶比活力约为２５Ｕ／ｍｇ蛋白,纯化４９倍,活力回收５８％,经ＰＡＧＥ及ＳＤＳ－ＰＡＧＥ测知该酶不含亚基,其分子量约为１４０ｋＤ。该酶最适ｐＨ为９．０,最适温度４７℃,用底物ＮＩＰＡＢ测活,其Ｋｍ值为６．２×１０~（－４）ｍｏｌ／Ｌ,Ｖｍ值为１．２４×１０４ｍｏｌ／Ｌ。此外还探讨了部分金属离子对该酶的影响。     

亲和层析纯化HepG2细胞分泌的PAI—1

本文报道用抗ＰＡＩ－１单克隆抗体（ＭｃＡｂ）亲和层析建立了纯化ＰＡＩ－１的简便方法。经免疫亲和层析,Ｓｅｐｈａｃｒｙｌ Ｓ２００凝胶过滤,从ＨｅｐＧ２细胞培液中分离到糖基化和非糖基化两种形式的ＰＡＩ－１,回收率为８４％,ＰＡＩ－１比活性为６．１×１０＾４ＩＵ／ｍｇ。糖基化ＰＡＩ－１分子量为５０ｋＤ,比活性５．８×１０＾４ＩＵ／ｍｇ。非糖基化ＰＡＩ－１分子量４３ｋＤ,占总ＰＡＩ－１３０％,仍具有ＰＡ     

带3蛋白转运吡啶二羧酸根离子的动力学研究

利用ＤＰＡ使Ｔｂ３＋的荧先强度显著增强的原理进行带３蛋白活性的测定,方法简便、灵敏、重复性好,而且能够进行连续荧光扫描测量．应用连续荧光扫描法测定了带３蛋白介导的ＤＰＡ与Ｃｌ－交换的动力学特征参数．结果表明,带３蛋白介导的ＤＰＡ与Ｃｌ－的交换对ＤＩＤＳ非常敏感,受ＤＩＤＳ的强烈抑制,抑制程度大于９０％;ＤＰＡ由内向外转运的米氏常Ｋｍ＝２８．１—３１．２ｍｍｏｌ／Ｌ;带３蛋白的天然底物Ｃｌ－从内侧竞争性抑制ＤＰＡ向外转运,抑制常数ｋｉ＝６０．４±６．９ｍｍｏｌ／Ｌ;膜内侧ＤＰＡ与外侧Ｃｌ－交换的活化能,在４—２５℃范围内为５．８±０．５ｋＣａｌ／ｍｏｌ２５—３７℃范围内为１９．８±１．５ｋＣａｌ／ｍｏｌ;膜内侧ＤＰＡ与外侧Ｃｌ－交换受转运介质ｐＨ（膜内外对称改变）的显著影响,ｐＨ＜７．４时,交换速度显著升高．本实验证明ＤＰＡ确是经带３蛋白而转运的,但转运机制可能与无机离子转运有所不同。     

亲和层析纯化HepG_2细胞分泌的PAI－1

本文报道用抗ＰＡＩ－１单克隆抗体（ＭｃＡｂ）亲和层析建立了纯化ＰＡＩ－１的简便方法。经免疫亲和层析,ＳｅｐｈａｃｒｙｌＳ２００凝胶过滤,从ＨｅｐＧ２细胞培液中分离到糖基化和非糖基化两种形式的ＰＡＩ－１,回收率为８４％,ＰＡＩ－１比活性６．１×１０４ＩＵ／ｍｇ。糖基化ＰＡＩ－１分子量为５０ｋＤ,比活性５．８×１０４ＩＵ／ｍｇ。非糖基化ＰＡＩ－１分子量４３ｋＤ,占总ＰＡＩ－１３０％,仍具有ＰＡＩ－１活性。用ＣｏｎＡ－Ｓｅｐｈａｒｏｓｅ亲和层析进一步纯化得到ＳＤＳ－ＰＡＧＥ纯的糖基化ＰＡＩ－１。     

蚯蚓纤溶酶的纯化及稳定性研究

蚯蚓纤溶酶（ＥＰＡ）抽提液经３０％ ～７０％ 饱和度的（ＮＨ４）２ＳＯ４ 盐析、ＤＥＡＥ—纤维素柱层析、Ｓｅｐｈａｄｅｘ Ｇ－７５葡聚糖凝胶过滤等纯化步骤,得到了具有纤溶活性的洗脱峰,置凝胶电泳后,得到四个活性组分,它们经５０℃保温６ｈ,活力上升６４％ ;在２ ｍ ｏｌ／Ｌ盐酸胍存在时,活力仅保存７．２％ ,当其浓度降低时,活力可恢复至９０％ ;在１％ ＳＤＳ存在时,活力仅保存１２．１％ ,但当ＳＤＳ除去时,活力又可恢复。因此,盐酸胍、ＳＤＳ均为ＥＰＡ 可逆性抑制剂。另外,ＥＰＡ 中含有较高的糖链（占总量的４５％ ）,具有良好的抵抗自水解作用。     

P物质对GABAA和GABAB受体介导的DRG神经元膜反应的调制作用

实验在幼年大鼠ＤＲＧ标本上进行。应用细胞内记录观察了ＳＰ对ＧＡＢＡ反应的调制作用。结果证明：（１）单独滴加ＳＰ（５×１０（－６）－４×１０（－５）ｍｏｌ／Ｌ）或浴槽灌流ＳＰ（１０（－６）－５×１０（－６）ｍｏｌ／Ｌ）不引起膜电位的改变或仅有轻微的去极化,但却能使ＧＡＢＡ引起的去极化反应减小５０．８±２０．２％（±ＳＤ）（２０／３０）;（２）单独滴加ＳＰ可使多数受检细胞ＡＰＤ５０延长２８．７±９．１％（±ＳＤ）（１０／１８）;（３）在预加ＳＰ后,能使ｂａｃｌｏｆｅｎ所引起的ＡＰＤ５０缩短效应（２０．６±２．９％,±ＳＤ）完全消除（４／１２）或翻转成ＡＰＤ（５０）延长１９．３±８．９％（±ＳＤ）（８／１２）;（４）预加ＧＡＢＡＢ受体激动剂ｂａｃｌｏｆｅｎ（１０（－４）－１０（－３）ｍｏｌ／Ｌ）３０—９０ｓ后明显地抑制ｍｕｓｃｉｍｏｌ（１０－４－１０－３ｍｏｌ／Ｌ）引起的去极化反应,其抑制效应达５４．４±１８．８％（±ＳＤ）（１７／２０）。由于ＤＲＧ神经元的胞体通常可用来作为研究初级传入终末的模型,因而本文实验结果提示：介导伤害性刺激信息的Ｐ物质在背角的释放,可能作用于初级传入终末,从而产生对抗ＧＡＢＡ介导的突触     

铝对玉米生长和硝酸还原酶活性的影响

测定了生长在Ａｌ２（ＳＯ４）３１００μｍｏｌ／Ｌ氮素营养液中的两个玉米品种（ＳＣ７０４和ＶＡ３５的根系和叶片）的ＮＡＤＨ－硝酸还原酶（ＥＣ１．６．６．１）和ＮＡＤ（Ｐ）Ｈ－硝酸还原酶（ＥＣ１．６．６．２）活性。     

人血红素加氧酶同工酶的分离纯化初报

首次报道了人肝脏血红素加氧酶的同工酶的分离纯化,并初步探讨了它们的性质,采用ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ－２５和羟基磷灰石柱层析法从人肝脏分离纯化ＨＯ的同工酶,酶活性检测、ＳＤＳ－ＰＡＧＥ分析结果显示,人肝脏微粒体含量ＨＯ的同工酶,按洗脱先后顺序分别得到分子量为３００００和３６０００的ＨＯ－１和ＨＯ－２．酶促反应中需相同辅酶参与,其中酶活性ＨＯ－１明显高于ＨＯ－２,两之比为２．４：１,从分子量和     

湖南尖吻蝮蛇毒两个出血毒素的纯化和理化性质

经ＳｅｐｈａｄｅｘＧ－７５凝胶过滤,ＱＡＥ－ＳｅｐｈａｄｅｘＡ－５０和ＣＭ－ＳｅｐｈａｄｅｘＣ－２５离子交换层析的步骤,从湖南产尖吻蝮（Ｄｉｅｎａｇｋｉｓｔｒｏｄｏｎａｃｕｔｕｓ）蛇毒中纯化出两个出血毒素（ＤａＨＴ－１和ＤａＨＴ－２）．ＳＤＳ－ＰＡＧＥ测得分子量均为２３．５ｋＤ,ＩＥＦ－ＰＡＧＥ测得等电点分别为５．６和５．２,两者具有相似的氨基酸组成,其中酸性氨基酸（Ａｓｘ,Ｇｌｘ）分别占２３％和２４％,ＤａＨＴ－１和ＤａＨＴ－２的最小出血剂量（ＭＨＤ）分别为０．５μｇ和０．８μｇ。都具蛋白水解酶活性,无对ＴＡＭＥ,ＢＡＥＥ的水解活性和ＰＬＡ２酶活性．两者的蛋白水解酶活力与出血活性并非正相关．ＤａＨＴ－１和ＤａＨＴ－２的最适温度分别为３５℃和４０℃,最适ｐＨ为６－９,对热均不稳定,温度高于６０℃活性完全丧失。金属离子的分析显示每摩尔毒素蛋白约含０．５ｍｏｌ的Ｚｎ,１ｍｏｌ的Ｃａ,较多的Ｎａ、Ｋ、Ｍｇ,不含Ｃｏ。     

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.