地衣芽孢杆菌β—甘露聚糖酶的纯化及其性质的研究

地衣芽孢杆菌１Ｂａｃｉｕｕｓ Ｌｉｃｈｅｎｉｆｏｒｍｉｓ）ＢＬ－３０６产生的胞外β－甘露聚糖酶经硫酸铵分级盐析,ＤＥＡＥ－纤维素柱层析。Ｓｅｐｈａｄｅｘ－Ｇ１００柱凝胶过滤和ＤＥＡＥ－纤维素柱再层析分离纯化,得到ＳＤＳ－聚丙烯酰胺凝胶电泳（ＳＤＳ－ＰＡＧＥ）均一样品。用ＳＤＳ－ＰＡＧＥ测得纯化后β－甘露聚糖酶分子量为２６０００道尔顿。用凝胶等电聚焦电泳（ＰＡＧＥＩＥＦ）测得等电点ＰＩ为５．０。该酶     

枯草芽孢杆菌中性内切β-甘露聚糖酶的纯化及性质

三草芽孢杆菌（Ｂａｃｉｌｌｕｓ ｓｕｂｔｉｌｉｓ）ＢＭ９６０２产生的中性内切β－甘露聚糖酶（ｅｎｄｏ－β－１,４－Ｄ－ｍａｎｎａｎ ｍａｎｎａｎｏｈｙｄｒｏｌａｅｓ,ＥＣ,３．２．１．７８）经硫酸铵分级沉淀、ＤＥＡＥ－纤维素（ＤＥ２２）离子交换柱层析,得到电泳纯的样品,提纯了４５．５倍,收率为５．９％。用ＳＤＳ－ＰＡＧＥ测得该酶的分子量为３５ｋＤ。用ＰＡＧＥＩＥＦ测得其等电点ｐⅠ为４．５。酶反应的     

青霉素酰化酶活性中心的定点突变

对Ｅ．ｃｏｌｅ ＡＴＣＣ １１１０５的青霉素酰化酶（ｐｅｎｉｃｉｌｌｉｎ Ｇ ａｃｙｌａｓｅ,ＰＧＡ）活性中心的Ｓｅｒ２９０分别进行了定点突变和和化学修饰,将活性中心的Ｓｅｒ２９０改变成Ｃｙｓ或Ｓｅｃｙｓ,ＰＧＡ水解活力均大为下降,但仍保留部分活性。其对底物６－硝基（３－苯乙酰氨基）苯甲酸（６－ｎｉｔｒｏ－３－ｐｈｅｎｙｌａｃｅｔａｍｉｄｏ ｂｅｎｚｏｉｃ ａｃｉｄ,ＮＩＰＡＢ）的ｋｃａｔ分别从１     

枸杞子糖蛋白的分离纯化、物化性质及糖肽键特征

从宁夏枸杞子提取得到的粗多糖,经ＤＥＡＥ－Ｃｅｌｌｕｌｏｓｅ和ＳｅｐｈａｄｅｘＧ－１００柱层析,得到均一的枸杞子糖蛋白ＬｂＧＰ。分子量由ＳＤＳ－ＰＡＧＥ测定为８８ｋｄ,糖含量为７０％,糖组成为Ａｒａ：Ｇａｌ：Ｇｌｃ＝２．５：１．０：１．０（摩尔比）,并含有其他１８种天然氨基酸。初步分析表明ＬｂＧＰ是Ｏ－连接的糖蛋白。     

双乙酰还原酶的分离纯化研究

比较了５种细菌、４种酵母菌和鸡肝中双乙酰还原酶含量,其中粪肠杆菌（Ｅｎｔｅｒｏ－ｃｏｃｃｕｓｆａｅｃａｌｉｓ）ＡＳ１．５９５中含量较高,为９．６ＩＵ／ｇ湿菌体。并对ＡＳ１．５９５菌酶和鸡肝酶进一步经ＳｅｐｈａｄｅｘＧ－１００和ＤＺＡＥ柱分离纯化,提纯倍数分别为４５、８９３,最后收率分别为１８．５％、５．１％。     

兔阑尾中一种新的21kD的钙结合蛋白的纯化与鉴定

纯化与鉴定了Ｂ淋巴细胞中一种新的分子量为２１ｋＤ的钙结合蛋白（ＣａＢＰ２１）。兔阑尾淋巴细胞匀浆经热变性,Ｐｈｅｎｙｌ－Ｓｅｐｈａｒｏｓｅ与ＤＥＡＥ－Ｓｅｐｈａｒｏｓｅ柱层析,自每１ｋｇ细胞沉积物中获得ＳＤＳ－ＰＡＧＥ均一的ＣａＢＰ２１５．３ｍｇ。ＨＣｌ水解后的酸性氨基酸（Ａｓｐ＋Ｇｌｕ）含量为２６％。如同大多数钙结合蛋白一样,Ｎ末端封闭阻止其进行Ｅｄｍａｎ降解。ＣａＢＰ２１中疏水性氨基酸（计Ｇｌｙ,不计Ｔｒｐ）约占４６％,碱性氨基酸１０％,酸性氨基酸与极性氨基酸约４４％。ＣａＢＰ２１有较高的Ｓｅｒ、Ｔｙｒ含量。肽谱分析等确证ＣａＢＰ２１为２个相同或相似亚基二聚体。以ＡｒｓｅｎａｚｏⅢ作Ｃａ２＋结合分析表明每分子ＣａＢＰ２１可结合４分子Ｃａ２＋,对Ｃａ２＋的结合常数约为１０－５ｍｏｌ／Ｌ。各种性质表明ＣａＢＰ２１是一种不同于其他已知钙结合蛋白的新钙结合蛋白。     

农业系统生产力（ASP）的量化及其现状分析

农业系统生产力（ＡＳＰ）的量化及其现状分析卢进登,韩纯儒（北京农业大学农学系,１０００９４）ＱｕａｎｔｉｆｉｃａｔｉｏｎｏｆＡｇｒｏｓｙｓｔｅｍＰｒｏｄｕｃｔｉｖｉｔｙ（ＡＳＰ）ａｎｄＡｎａｌｙｓｉｓｏｎｉｔｓＣｕｒｒｅｎｔＳｉｔｕａｔｉｏｎｉｎＣｂｉｎａ￥．ＬｕＪｉｎ－ｄｅｎｇ;ＨａｎＣｈｕｎｒｕ（ＢｅｉｊｉｎｇＡｇｒｉｃｕｌｔｕｒａｌＵｎｉｖｅｒｓｉｔｙｆＢｅｉｊｉｎｇ１０００９４）．ＣｈｉｎｅｓｅＪｏｕｒｎａｌｏｆＥｃｏｌｏｇｙ,１９９３,１２（２）：２１－２２．ＢａｓｅｄｏｎａｂｒｉｅｆａｎａｌｙｓｉｓｏｎｔｈｅｆｏｒｍａｔｉｏｎｐｒｏｃｅｓｓｏｆＡＳＰ,ｉｔｓｃｏｎｃｅｐｔｉｓｄｅｓｃｒｉｂｅｄａｎｄａｎｉｎｔｅｇｒａｔｅｄｉｎｄｉ－ｃａｔｏｒｆｏｒｉｔｓｑｕａｎｔｉｆｉｃａｔｉｏｎ—ＡＳＰ２ｉｓｐｕｔｆｏｒｗａｒｄｓ．Ｆｒｏｍｔｈｏｓｅ,ｔｈｅＡＳＰｌｅｖｅｌｓｉｎｖａｒｉｏｕｓｒｅｇｉｏｎｓｏｆＣｈｉｎａａｒｅａｎａｌｙｚｅｄａｎｄ８ｌｅｖｅｌｓａｒｅｄｉｖｉｄｅｄｂｙｕｓｉｎｇ．Ｈｉｅｒａｒｃｈｉｃｃｌｕｓｔｅｒｉｎｇｍｅｔｈｏｄ．Ｉｔ’ｓ：ｃｌａｒｉｆｉｅｄｔｈａｔＡＳ－ＰＩｉｓａｍｏｒｅ     

羊肚菌多糖的分离纯化及组成结构分析

液体深层发酵所得的羊肚菌（Ｍｏｒｃｈｅｌｌａ ｅｓｓｕｌｅｎｔａ Ｌ．）营养液经超过滤法去掉小分子量组分,脱脂,脱色,脱蛋白质,减压低温浓缩,用超速离心法分离提纯,再用乙醇沉淀法反复多次将所要的多糖沉淀提纯,得到羊肚菌多糖（ＭＥＰ）。对其中分子量为１００００￣１０００００的多糖（ＭＥＰ－ＳＰ）,采用ＤＥＡＥ－纤维素离子交换柱,以不同浓度ＮａＣｌ为洗脱液,进行纯化分离,再经Ｓｅｐｈａｒｏｓｅ ＣＬ－     

高及低转移潜能小鼠肝癌细胞株糖蛋白凝集素结合特征的研究

为探讨肿瘤转移与细胞表面的糖结构的关系,对小鼠肝癌细胞的高、低淋巴道转移株Ｈｃａ－Ｆ和Ｈｃａ－Ｐ进行了蛋白质电泳及经蛋白质印迹术后的５种凝集素（ＣｏｎＡ、ＷＧＡ、ＵＥＡ、ＳＢＡ、ＰＮＡ）结合糖蛋白谱的对比分析．结果表明：高、低转移两株细胞的ＳＤＳ－ＰＡＧＥ谱基本相同;ＣｏｎＡ特异结合糖蛋白共有５种（～７２,８０～９０,～１０４,～１５０,～２００ｋＤ）;其中较明显的差异为～７２ｋＤＣｏｎＡ特异结合糖蛋白,它在Ｈｃａ－Ｐ细胞的表达明显高于Ｈｃａ－Ｆ细胞．ＷＧＡ特异结合糖蛋白１种（～１５０ｋＤ）,在Ｈｃａ－Ｐ细胞的表达略高于Ｈｃａ－Ｆ细胞．此外,实验发现两种性质未明的蛋白质（～７９,～１３０ｋＤ）,后者在Ｈｃａ－Ｐ细胞的含量明显高于Ｈｃａ－Ｐ细胞．结果提示Ｈｃａ－Ｆ和Ｈｃａ－Ｐ细胞不同的转移表型可能与其糖蛋白的表达有一定的关联．     

云南溪菜多糖的分离纯化及其性质研究

从云南溪菜中提取的水溶性胞外粗相糖（ＥＰＳ）,用Ｓｅｖａｇ法脱蛋白后,经ＤＥＡＥ－纤维素柱层析和葡萄糖凝胶Ｇ－２００柱层析可得到纯品。溪菜多糖复合物经碘试验证明含有少量淀粉,Ｂａｃｌ２试验检测出含有ＳＯ４＾２－,琼脂糖凝胶电泳显示含有糖类及蛋白南,且其组成不均一。用Ｌｏｗｒｙ法测得蛋白质含量为１３．５４％,苯酚－硫酸法测得糖含量为７８％,经薄层层析和纸层析鉴定,溪菜多糖复合物的酸水解物中含有大量Ｄ     

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.     

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     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).