芳香黄杆菌弹性蛋白酶的纯化及性质研究

报道了弹性蛋白亲和层析分离纯化芳香黄杆菌产胞外弹性蛋白酶。经一步柱层析可获聚丙烯酰胺凝胶电泳均一的酶制品,收率可达５０％,并制备了酶的结晶。该酶在ＳＤＳ－ＰＡＧＥ上测得分子量为２１３８０,ＩＥＦ－ＰＡＧＥ测得等电点８．９,最适作用温度为５０℃,最适作用ｐＨ为７．４,在４０℃以下热稳定性良好,ｐＨ４．５－９．５范围内稳定,重金属离子Ｆｅ３＋、Ｚｎ２＋、Ｃｒ３＋、Ｃｏ２＋、Ｈｇ２＋、Ｎｉ２＋、Ａｇ＋、Ｃｕ２＋等严重抑制酶活性,黄杆菌弹性蛋白酶除了特异水解弹性蛋白外,对干酪素、血纤维蛋白、白蛋白、明胶、血红蛋白等多种蛋白质均能水解。     

链霉菌Z94-2碱性脂肪酶产生条件及酶学性质

在１５２株脂肪酶产生菌中,链霉菌Ｚ９４－２产脂肪酶活力为５９６ｕ／ｍＬ,其最适培养基（ｇ／Ｌ）为：糊精１０、黄豆饼粉３０、尿素１０、Ｋ２ＨＰＯ４０．５、ＭｇＳＯ４０．５、ＮａＣｌ１和ＡＥＯ９０．５,产酶的最适条件为：初始ｐＨ９．５～１０．０,在２６℃培养４８ｈ。用ＰＶＡ橄榄油乳化系统测定该酶的最适ｐＨ９．８,最适温度３７℃,在ｐＨ８．６～１０．２于５℃存放２４ｈ,酶活力不变。０．１４ｍｏｌ／Ｌ的氯     

芳香黄杆菌弹性蛋白酶的纯化及性质研究

报道了弹性蛋白亲和层析分离弛化芳香黄杆菌产胞外弹性蛋白酶,经一步柱层析可获聚丙烯酰胺凝胶电泳均一的酶制品,收率可达５０％,并制备了酶的结晶。该酶在ＳＤＳ－ＰＡＧＥ上测得分子量为２１３８０,ＥＦ－ＰＡＧＥ测得等电点８．９最适作用温度为５０℃,最适作用,ＰＨ为７．４在４０℃以下热稳定性良好,ＰＨ４．５－９．５范围内稳定,重金属离子Ｆｅ＾３＋,Ｚｎ＾２＋,Ｃｏ＾２＋,Ｈｇ＾２＋,Ｎｉ＾２＋Ａｇ＾＋,Ｃｕ     

产碱菌（Alcaligenes sp.）119转化苯丙酮酸形成L—苯丙氨酸的研究

从土壤中分离到一株产碱菌１１９,能将苯丙酮酸一步转化成Ｌ－苯丙氨酸。酶反应的最适ｐＨ为８．５,该酶在ｐＨ８－９之间稳定,最适反应温度为３７－４５℃,金属离子Ｆｅ＾２＋,Ｍｎ＾２ｎ等对酶有不同程度的抑制作用。该菌株培养在由葡萄糖,蛋白胨、牛肉膏等组成的培养基中,可获得最高转化率。Ｌ－天冬氨酸为酶反应的最佳氨基供体。当苯丙酮酸浓度为０．２ｍｏｌ／Ｌ时,细胞在３７℃下反应１６小时,可产Ｌ－苯丙氨酸３０．     

链霉菌Z94-2碱性脂肪酶产生条件及酶学性质

在１５２ 株脂肪酶产生菌中,链霉菌Ｚ９４２ 产脂肪酶活力为５９６ｕ／ ｍＬ,其最适培养基（ｇ／Ｌ） 为：糊精１０ 、黄豆饼粉３０ 、尿素１０ 、Ｋ２ＨＰＯ４ ０－５ 、ＭｇＳＯ４ ０－５ 、ＮａＣｌ １ 和ＡＥＯ９ ０ ．５ ,产酶的最适条件为：初始ｐＨ９ ．５ ～１０－０ ,在２６ ℃培养４８ｈ 。用ＰＶＡ 橄榄油乳化系统测定该酶的最适ｐＨ９ ．８ ,最适温度３７ ℃,在ｐＨ８－６ ～１０－２ 于５ ℃存放２４ ｈ ,酶活力不变。０－１４ｍｏｌ／Ｌ 的氯化钙有较大的激活作用。     

土曲霉金色变种AT8951菊粉酶的纯化和性质的研究

土曲霉金色变种ＡＴ８９５１菊粉酶粗酶液经硫酸铵分段沉淀、ＤＥＡＥＣｅｌｕｌｏｓｅＤＥ３２离子交换、超滤、ＳｅｐｈａｄｅｃＧ－１５０凝胶过滤和ＦＰＬＣ,获得两个菊粉酶组分ＥＩ和ＥＩＩ,经分析型ＦＰＬＣ和ＰＡＧＥ鉴定为单一纯和分析纯。ＥＩ分量为６６ＫＤ,适适作用温度和ＰＨ分别５５℃和５．８;ＥＩＩ分子量为５６ＫＤ,最适作用温度为５７℃,最适ＰＨ为６．０。ＥＩ和ＥＩＩ皆为糖蛋白,多糖含量分别为２４．７％     

微生物生产弹性蛋白酶的研究

从１０个不同省区采集的５００多个土样中,分离得到了多株产弹性蛋白酶的菌株,主要集中在黄杆菌属和色杆菌属中。经过细胞工程技术处理后,黄杆菌属中的Ｆ－１２２菌在摇瓶发酵中的产酶能力达到２４０ｕ／ｍｌ,比出发菌株提高了１．５倍。该酶在Ｔｒｉｓ—ＨＣｌ缓冲液中最适ｐＨ为８．０,最适酶解温度４３℃。在ｐＨ６．０—９．５范围内稳定。ＣｕＳＯ４、ＺｎＳＯ４和ＦｅＳＯ４强烈抑制酶的活性,ＮａＣｌ、ＫＣｌ对酶活影响微弱。６０℃,３０ｍｉｎ酶活完全丧失。     

曲霉木聚糖酶发酵条件与性质

从实验室培养污染物上分离出一株产木聚糖酶活力高的曲霉（ＡｓｐｅｒｇｉｌｌｕｓＳｐ．）Ａ３菌株。研究了其发酵过程,该菌经３０℃,培养９６小时,酶活力可达３２０ＩＵ／ｍｌ,研究了碳源,氮源,发酵起始ｐＨ值及通风量对产酶的影响。酶的最适反应温度为５５℃,最适ｐＨ值为４．４。在不同温度下保温１小时,测得该酶的半失活温度为５１℃。     

β-葡萄糖苷酶的分离纯化和性质研究

β－葡萄糖苷酶是纤维素酶的重要组分之一,它不仅可水解纤维二糖和寡糖,更可解除纤维二糖对β－１,４－内切葡聚糖酶和外切葡聚糖酶的抑制,提高水解速率和程度．利用ＳｅｐｈａｄｅｘＧ－１５０和ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ－５０层析法从黑曲霉变异株Ｌ－２２中分离提纯了β－葡萄糖苷酶,该酶是由两个分子量相同的亚基组成的二聚体,每个亚基分子量为２０３ｋＤ．该酶最适ｐＨ为４．８,ｐＨ稳定范围在３．６～６．４;最适温度是６０℃,温度稳定范围为４～６０℃;酶分子含糖量为８．３５％．它是一个酸性β－葡萄糖苷水解酶,专一性地水解β－糖苷键．而不水解α－糖苷键,对短链底物表现了相对高的活力．用动力学分析和共价化学修饰方法探讨了与该酶活力有关的必需基团．由ｐＨ对ｌｇＶｍ和ｌｇＶｍ／Ｋｍ的影响,推测出酶活性部位至少有两个可解离基团为酶活性所必需,它们在酶－底物复合物中的ｐＫｅｓ１和ｐＫｅｓ２的值分别为４．０和５．６,在游离酶中的ｐＫ值分别为４．２和５．９．由此可初步判断这两个可解离基团可能为组氨酸和含羧基的氨基酸,它们与酶的催化和底物结合可能有关．     

温特曲霉HD1的鉴定及其对氧蒽类染料脱色特性的研究

从土壤中分离到１株染料脱色真菌,经鉴定命名为温特曲霉ＨＤ１。该菌对氧蒽类染料虎红具有很强的脱色能力。温度在２８￣４０℃之间,ＨＤ１对虎红的脱色率为９３￣９９％,最适脱色温度为３３℃,ｐＨ值在４．０￣８．０之间,其脱色率为８９．３￣９８．８％,最适脱色ｐＨ值为６．０。培养基、碳源,氮源及接种量对其脱色率均有影响,该菌对虎红的脱色酶为组成酶,主要分布在细胞内,染料的加入能改变脱色酶在胞内外的分配比例,     

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.     

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.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

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).