固定化脂肪酶催化聚乙二醇脂肪酸酯的合成

固定化假丝酵母（Ｃａｎｄｉｄａｓｐ．）－１６１９脂肪酶催化脂肪酸和不同聚合度的乙二醇形成酯。其中以聚乙二醇４００（ＰＥＧ４００）的酯化率较高,Ｃ_１０－Ｃ_１８的饱和脂肪酸与ＰＥＧ４００反应的酯化率相仿。反应体系中,月桂酸与ＰＥＧ４００的摩尔比大于２∶１时有利于酯化反应,作用的最适温度为４０℃,最适Ｐｈ为６.０。在比较的３０种添加有机溶剂中,饱和烷烃,芳香烃能促进反应,使酯化率提高２０％左右。反应开始添加５μｌ水有利于酶的作用,外加水量超过适量时,随外加水量的增加酯化率下降。在由２.５ｍｍｏｌ月桂酸,１.２５ｍｍｏｌＰＥＧ４００,１０ｍｇ固定化脂肪酶（１００ｕ）,５ｍｌ己烷,５μｌ水组成的反应体系中,４０℃振荡反应２２ｈ,酯化率达４９.８％。经薄层色谱,气相色谱鉴定,产物为聚乙二醇４００月桂酸酯。     

固定化假丝酵母1619脂肪酶催化油酸油醇酯的合成

比较了14种不同来源的脂肪酶催化油酸油醇酯的合成。其中,假丝酵母(Candidasp．)1619脂肪酶酯化能力最强,以硅藻土为载体,分别按0．1％添加椰子油、吐温80．按l％添加MgSO43种共固定物,醇化反应初速度提高了1．5倍。此固定化酶催化油酸油醇酯合成的最适温度为30℃,0～60℃下反应24h的酯化率均在90％以上,100℃下还有10．25％的酯化率。最适酯化pH6．0。反应中去水,可使终酯化率提高到99％。在添加的23种有机溶剂中,以异辛烷促进酯化的效果最好．正壬烷和正己烷次之。此固定化酶在28℃下批式重复反应的半衰期为990h,柱式固定床反应器中28℃连续运转1000h后酯化率为78％。     

微水体系中荧光假单胞菌脂肪酶催化合成单甘酯

研究了无溶剂微水体系中荧光假单胞菌脂肪酶 (PFL)催化油脂甘油解合成单甘酯的反应因素以及多温程非均相固液反应对单甘酯产率的影响。以初始体系最低共熔点 (PFL)取代临界温度学说中的油脂初熔点 ,通过考察不同IEP体系的甘油解 ,发现PFL酶促油脂甘油解时存在碳链基质特异性的函数关系 ,即反应物油脂中饱和碳残基的质量百分含量 (C₁₆+C₁₈)与单甘酯产率间符合以下多项式:Y =- 0.0006X³ +0.0592X²-0.8909X+26.753(13%<X<76.5%),式中X为C₁₆+C₁₈,Y为40℃时等温反应条件下的单甘酯产率。IEP为40℃时,最适等温反应条件如下：加水量3%～4.5%,加酶量为500μ/g油酯摩尔比1：2.5-5.0(油酯：甘油)反应温度40℃.实验条件下多步等程序降温反应48h后单甘酯最高产率为81.4%.     

微生物脂肪酶在正庚烷中合成短链芳香酯的研究

用微生物脂肪酶在溶剂相中合成短链芳香酯的研究表明：脂肪酶在正庚烷中催化合成芳香酯转化率比水相中有明显的优势。在10个不同来源的商品脂肪酶中,选择了其中对己酸乙酯转化率在85％以上来自Mucor miehei,Candida rugosa和Porcine pancreas的脂肪酶对7个短链脂肪酸酯进行合成,其中Mucor miehei脂肪酶对这几个芳香酯48 h合成转化率均在90％以上,乙酸乙酯21．28g^-1．丙酸乙酯19．6gL^-1,丁酸乙酯26．61gL^-1,戊酸乙酯24．95gL^-1,己酸乙酯产量34.60gL^-1,丁酸异戊酯30.76gL^-1,乙酸异戊酯12．76gL^-1。同时．Mucor miehei脂肪酶在正庚烷批式反应中稳定性也较好,己酸乙酯半衰期为120h,最少的乙酸乙酯也在140h。并且还发现脂肪酶在正庚烷中分解酶活降低很多,但对其酯合成转化率没有直接的影响。     

生物法合成维生素C棕榈酸酯

研究了不同的脂肪酶在有机溶剂体系中催化合成L-维生素C棕榈酸酯的反应。针对维生素C在有机溶剂中溶解度较低这一问题,对催化合成维生素C棕榈酸酯反应的脂肪酶和反应介质进行比较,同时对影响合成维生素C棕榈酸酯反应的因素（温度、底物浓度、底物摩尔比、反应时间和酶量等）进行探讨,优化了反应条件：在10mL的丙酮中,1.094g棕榈酸与0.107g维生素C在酶量为20％（W/W, 固定化酶/维生素C）的固定化脂肪酶催化下,初始含0.4nm分子筛20%,温度为60℃,转速为200r/min,反应48h转化率可以达到80%,产物维生素C棕榈酸酯的浓度可达20g/L。     

脂肪酶合成聚乙二醇400油酸单酯和双酯的影响因素

研究了固定化假丝酵母(Candida sp.)-1619脂肪酶合成聚乙二醇400油酸单酯与双酯的影响因素。不同摩尔比的底物反应6h都有单酯和双酯生成。酸与醇的摩尔比为O.25：1到2：1时,生成单酯与双酯的比例在3.5：1到4:1的范围内;当酸与醇的摩尔比达到3：1至8:1时,单、双酯的生成量相仿。反应达平衡时(24h),不同摩尔比底物的反应产物都是双酯。在含己烷的反应体系中,反应平衡时有单酯存在,摩尔比为2：1时,反应物中单、双酯比达到l：3.2。     

微乳液中脂肪酶对扁桃酸乙酯水解反应和α－溴丙酸酯化反应的催化作用

针对脂肪酶作用于相界面和微乳液油水界面膜的特点,首次将柱状假丝酵母脂肪酶(Candida cyclindracea Lipase)加入水包油(o／w)型微乳液及油包水相似文献   

合成己酸乙酯脂肪酶产生菌的筛选及产酶条件

从２７株脂肪酶产生菌中筛选到能由乙醇和己酸合成己酸乙酯的菌株８株。其中Ｒｈｉｚｏｐｕｓｓｐ．Ｈ－３菌株脂肪酶活力为５０－６０ｕ／ｍｌ,全细胞在有机溶剂中的酯化率可达己酸的９１％。Ｈ３产酶的最适碳源为淀粉或葡萄糖。６％黄豆饼粉加４％蛋白陈复合氮源有利于酶活力的增加。     

有机相酶促酯化反应中水分调控技术的研究

在有机相酶促反应中,水含量是影响酶活力的关键因素.对异辛烷/正辛醇体系中柱状假丝酵母脂肪酶催化萘普森酯化反应中的水分调控技术进行了研究. 结果表明：水合盐对——Na₂SO₄·10H₂O/Na₂SO₄对系统水分的变化具有有效的缓冲作用;非极性硅藻土吸附固定酶,使之对水分的敏感性得到缓解;另外,加入分子筛去除副产物——“水”可促进酯化过程的进行.     

环氧丙醇酯立体专-性水解酶产生菌的筛选*

从土壤中筛选出一株能拆分（Ｒ,Ｓ）－环氧丙醇丁酸酯的根霉（Ｒｈｉｚｏｐｕｓｓｐ．Ｂｃ０－０９）,该菌株所产胞外脂肪酶在水解环氧丙醇丁酸酯的反应中具有良好的立体专一性。在ｐＨ恒定７．０的条件下,以其发酵液水解底物,当转化率为５８％时,残留的（Ｒ）－环氧丙醇丁酸酯的光学纯度（对映体过量值）达９６．１％。     

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.     

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.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.