桦褶孔菌漆酶固定化及其对染料的降解

采用壳聚糖交联法和海藻酸钠-壳聚糖包埋交联法固定化桦褶孔菌产生的漆酶,探讨最佳固定化条件,固定化漆酶的温度,pH稳定性及操作稳定性,并以两种固定化酶分别对4种染料进行了降解.结果表明:(1)壳聚糖交联法固定化漆酶的最佳条件为:壳聚糖2.5%,戊二醛7%,交联时间2h,固定化时间5h,给酶量1g壳聚糖小球:1mL酶液(1U/mL),固定化效率56%;(2)海藻酸钠-壳聚糖包埋交联法固定化漆酶的最佳条件为:海藻酸钠浓度4%,壳聚糖浓度0.7%,氯化钙浓度5%,戊二醛浓度0.6%,给酶量4mL 4%海藻酸钠:1mL酶液(1U/mL),固定化效率高达86%;(3)固定化的漆酶相比游离漆酶有更好的温度和pH稳定性;(4)比较两种固定化漆酶,海藻酸钠-壳聚糖包埋交联法固定化酶的温度及酸度稳定性要优于壳聚糖固定化酶,但可重复操作性要弱于后者,两者重复使用8次后的剩余酶活比率分别为71%及64%;(5)两种固定化酶对所选的4种不同结构的合成染料均有较好的降解效果,其中壳聚糖固定化酶对茜素红的降解效果及重复使用性极佳,重复降解40mg/L的茜素红10次,降解率仍保持在100%.     

固定化酶法手性转化右旋磷霉素的初步研究

研究确定沙门柏干酪青霉菌（Penicillium camemberti）2221能够产生手性转化右旋磷霉素的酶,以及以海藻酸钠为载体固定化酶转化的最适条件。以海藻酸钠为载体,分别考察了海藻酸钠浓度、氯化钙浓度、海藻酸钠和酶用量的体积比、固定化时间等条件,以及固定化酶的最适反应pH、最适反应温度和反复利用的稳定性等。结果表明,最优固定化条件是3.0%（质量与体积比）海藻酸钠、3.0%（质量与体积比）氯化钙、酶液（浓缩20倍）和3.0%（质量与体积比）海藻酸钠溶液的体积比为1 2、固定化时间为6 h。固定化酶的最适温度为37℃,最适pH为6.2,转化率为14.3%,连续反应4次后转化率为最初的57.57%。利用海藻酸钠包埋固定化沙门柏干酪青霉菌产生的手性转化右旋磷霉素的酶,能够连续转化生成左旋磷霉素,提高酶的利用效率,延长使用时间,具有进一步研究开发的价值。     

金属框架结构材料MOF-199对漆酶的固定化及其性质

以金属框架结构材料MOF-199为载体对漆酶进行固定化,并对固定化酶的性质进行初步研究。首先,以3-氨基丙基三乙氧基硅烷对载体MOF-199进行表面氨基化修饰,再用戊二醛对载体进行活化,最后对漆酶进行固定化。固定化条件优化结果表明:在漆酶质量浓度0.3 g/L,戊二醛用量1%(体积分数),pH 4.8下固定7 h,制得固定化酶活性最高。对固定化酶的研究发现:最适反应温度为40℃,最适pH为5.2,在连续操作7次后,固定化酶的活力仍能保持在51%。固定化漆酶热稳定性,pH耐受性,贮存稳定性均明显高于游离漆酶。     

乙二醇缩水甘油醚交联海藻酸钠-羧甲基纤维素钠固定化脂肪酶

以海藻酸钠、羧甲基纤维素钠(CMC)为载体,分别以乙二醇缩水甘油醚(EGDE)和戊二醛为交联剂,采用包埋交联法对脂肪酶进行固定化,结果显示EGDE的交联效果要优于戊二醛,添加EGDE的固定化酶酶活最好。得到制备固定化酶的最优方案为海藻酸钠2.5%,CMC浓度1.5%,给酶量800U/ml复配载体,氯化钙5%,以0.02%的EGDE交联固定30min,由此制备得到酶活约为380 U/g的固定化酶,酶活收率约为50.09%。固定化酶的最适反应p H为8.5,比游离酶增大0.5个单位;最适反应温度是45℃,比游离酶提高5℃;耐热性能变好,且重复使用7次后仍能保持60%左右的相对酶酶活。     

海藻酸钠固定化重组川芎咖啡酸-3-O-甲基转移酶

利用IPTG诱导含有川芎咖啡酸-3-O-甲基转移酶(LCCOMT)的大肠杆菌工程菌E.coli BL21(DE3)/pET28a-LCCOMT,经Ni~(2+)亲和层析、质谱鉴定获得纯化的LCCOMT。采用海藻酸钙凝胶包埋固定LCCOMT,单因素实验考察最佳固定化条件对固定化酶活力的影响,并确定了固定化酶的最适温度、pH值、Km、Vmax与反应批次等酶学性质。确定的条件分别为海藻酸钠质量分数1.5%,CaCl_2浓度2.5 g/L,固定化时间2 h,载体与酶质量比40 000∶1。通过正交实验确定最终固定化条件为CaCl_2浓度2.5 g/L,海藻酸钠质量分数2.0%,固定化时间1 h,载体与酶质量分数35 000∶1时,固定化效果最好,此时相对酶活力为75.43%。固定化酶的最适催化温度为37℃、最适pH值为7.5,较游离酶分别增加0℃和0.5;Km、Vmax分别增高0.40和0.74;实验确定固定化酶的半衰期,连续使用6次,酶活力仍保留50%。     

壳聚糖固定化真菌漆酶及其用于处理酚类污染物的研究

Trametessp. AH282在液体培养条件下经邻甲苯胺诱导能有效合成漆酶同工酶A。以壳聚糖为载体,戊二醛为交联剂进行了漆酶A的固定化研究,确定酶固定化适宜条件为：0.1g壳聚糖与15 mL 5%戊二醛交联8 h后,加入30.0U酶固定12h。在此条件下获得的固定化漆酶催化能力为176.4U/g载体,酶活回收率58.5%。与游离酶相比,固定化漆酶与作用底物愈创木酚的亲和力降低,但固定化酶的稳定性有明显改善。固定化漆酶的最适温度为55℃,比游离酶提高5℃;70℃条件下保温8 h,固定化酶保留酶活56.5%,而在相同条件下游离酶酶活明显下降。使用固定化漆酶反应装置进行酚类化合物转化实验,连续进行12批次操作,固定化酶酶活仍保持60%以上,漆酶使用效率明显提高。     

米曲霉F-81产中性蛋白酶的固定化条件及其特性

以海藻酸钠为载体,戊二醛为交联剂固定化米曲霉F-81产中性蛋白酶,研究了固定化条件及固定化酶的性质。结果表明,固定化的最佳条件为:固定化时间1 h、海澡酸钠浓度4%、戊二醛浓度9%、CaCl2浓度0.7 mol/L。在此条件下固定化的中性蛋白酶活力为游离酶活力的68%。固定化酶的最适作用温度为65℃,最适作用pH值为7.0。60℃下酶稳定性较好,80℃下处理60 min,粗酶中几乎检测不到酶活力;中性蛋白酶pH稳定范围为6.5-9.5。Km值为24.83 mg/mL,最大反应速率Vmax为0.043 12 mg/min。     

固定化黑曲霉β-葡萄糖苷酶制备染料木素活性苷元的研究

比较了以海藻酸钠为载体,用胶囊法、包埋-交联法、交联-包埋法三种不同方法固定化黑曲霉β-葡萄糖苷酶的效果,并研究了最佳固定化方法的固定化条件和固定化酶的部分性质。结果表明,交联-包埋法即β-葡萄糖苷酶与0.20%戊二醛交联后再用2.0%海藻酸钠包埋的固定化方法中酶结合效率和酶活力回收率最高。海藻酸钠浓度和戊二醛浓度对酶结合效率影响较大,戊二醛浓度和包埋颗粒直径大小对酶活力回收率影响显著。与游离酶相比,制备的固定化酶最适温度、最适pH值和Km值分别由50℃、4.5和2.57μg/mL下降到40℃、4.0和2.02μg/mL。固定化酶具有更强的耐酸性和稳定性。该固定化酶用于大豆异黄酮活性苷元染料木素的合成,重复使用6次后,固定化酶的活力仍保持84.94%,染料木苷转化率为56.04%。     

固定化黑曲霉β-葡萄糖苷酶制备染料木素活性苷元的研究

比较了以海藻酸钠为载体,用胶囊法、包埋-交联法、交联-包埋法三种不同方法固定化黑曲霉β-葡萄糖苷酶的效果,并研究了最佳固定化方法的固定化条件和固定化酶的部分性质。结果表明,交联-包埋法即β-葡萄糖苷酶与0.20%戊二醛交联后再用2.0%海藻酸钠包埋的固定化方法中酶结合效率和酶活力回收率最高。海藻酸钠浓度和戊二醛浓度对酶结合效率影响较大,戊二醛浓度和包埋颗粒直径大小对酶活力回收率影响显著。与游离酶相比,制备的固定化酶最适温度、最适pH值和K_m值分别由50℃、4.5和2.57 μg/mL下降到40℃、4.0和2.02 μg/mL。固定化酶具有更强的耐酸性和稳定性。该固定化酶用于大豆异黄酮活性苷元染料木素的合成,重复使用6次后,固定化酶的活力仍保持84.94%,染料木苷转化率为56.04%。     

海藻酸钠包埋法制备固定化菠萝蛋白酶

以海藻酸钠为载体,包埋法固定菠萝蛋白酶,对固定化奈件进行优化,同时探讨固定化菠萝蛋白酶的部分酶学性能。结果表明：固定化菠萝蛋白酶的质量受海藻酸钠质量分数、固定化酶量、固定化时间以及CaCl2质量分数的影响,其最佳固定化条件为：海藻酸钠质量分数1．0％,CaCl2质量分数3％,固定化酶液量与海藻酸钠体积之比1：2,固定化时间60min,在此条件下,制备的固定化菠萝蛋白酶的比活力为211．8U／g（湿质量载体）,由此制得的固定化酶的最适pH为7．6,与游离酶相比,升高了0．8个pH单位,同时显示固定化菠萝蛋白酶能耐受较高的碱性环境,固定化酶最适温度与游离酶相同,均为50℃,固定化酶在较高温度范围内,仍能保持较高的相对活力。     

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).     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.