超声波协同复合酶法提取姬松茸多糖

研究了超声波协同复合酶法提取姬松茸多糖的最佳工艺条件。采用均匀设计法分别考察不同时间、pH值、温度、酶浓度、固液比对纤维素酶、果胶酶以及木瓜蛋白酶酶解反应的影响,并研究三种酶联合使用时的加酶方式以及超声波协同提取时的最佳条件。结果表明,超声波协同复合酶法可显著提高姬松茸多糖的提取率,其最佳提取条件为：超声波作用20min,分步加酶法（先加果胶酶：pH值3．8、温度50℃、时间90min、加酶量7000U／g、固液比1：45;然后加纤维素酶：pH值3．6、温度75℃、时间120min、加酶量150U／g、固液比1：45;最后加木瓜蛋白酶：pH值3．6、温度75℃、时间120min、加酶量20000U／g、固液比1：45）,多糖提取率达到14．51％。     

酶解辅助水蒸汽蒸馏法提取紫枝玫瑰精油工艺研究

为了优化酶解法辅助水蒸汽蒸馏法提取紫枝玫瑰精油的工艺,筛选出了能够有效提高精油香气主成分含量及精油提取率的果胶酶和纤维素酶,通过单因素试验,探索酶用量、酶解温度、酶解p H对玫瑰精油香气主成分及精油提取率的影响,在此基础上,利用正交分析,确定酶解-水蒸汽蒸馏法提取紫枝玫瑰精油的最佳工艺条件为:添加果胶酶和纤维素酶的复合酶体系,酶用量3 000 U/g,酶解温度50℃,酶解p H 5.5。采用此工艺条件,紫枝玫瑰精油的提取率是0.243 9%。     

酶法提取银杏黄酮类化合物研究

本文研究了纤维素酶酶解法提取银杏总黄酮工艺。与传统的乙醇提取工艺相比,银杏总黄酮得率提高了18．92％。实验确定了最佳提取条件：酶浓度0．40mg／mL,酶作用时间120min,酶解温度50℃,酶解介质pH值为4．5,乙醇浓度70％,提取温度70℃。     

复合酶预处理法对银杏叶总萜内酯提取率的影响

为研究复合酶预处理法对银杏叶总萜内酯浸出率的影响。本文采用单因素实验对银杏叶酶解预处理过程中的酶种类、酶用量、酶解时间、酶解温度、p H值五个关键因素进行探索,酶解后用20%乙醇-水溶液对银杏叶酶解液进行回流提取,LX-5型大孔吸附树脂对提取液进行纯化,浓缩干燥得银杏叶提取物产品。高效液相色谱法检测其总萜内酯含量。结果表明,银杏叶酶解预处理法的最佳工艺为:复合酶(纤维素酶∶果胶酶=1∶1),用量为银杏叶的1/300、酶解时间4.0 h、酶解温度50℃、初始p H值4.0。在该工艺条件下获得的银杏叶总萜内酯提取率为0.55%,银杏叶提取物中总萜内酯含量为8.96%,高于银杏叶提取物国际商务标准(总内酯含量≥6%)。说明复合酶预处理条件下银杏叶总萜内酯提取率高,研究为工业化生产高质量银杏叶提取物提供了理论依据。     

内生青霉菌纤维素酶辅助提取槐米总黄酮

研究内生青霉菌（Penicillium sp．B-4）胞外纤维素酶在槐米总黄酮提取中的辅助应用。内生青霉菌在起始pH4,5的综合马铃薯培养基中,150r／min,40℃下摇瓶,培养7d,具有较高的纤维素酶比活力（3．57U／mL）。槐米干粉投入青霉菌发酵液中进行酶解处理,比较酶料比、酶解温度、酶解时间和酶解液pH对槐米总黄酮提取率的影响,发现槐米干粉以酶料比40：1（mL／g）加入粗酶液中,在pH4．5、温度40℃下酶解处理1h后,黄酮提取率可达12．2％,比常规提取率增加了38．7％。内生菌纤维素酶辅助提取法为槐米黄酮提取的可行新方法。     

忽地笑中石蒜碱酶法提取及分离工艺研究

对复合酶法提取忽地笑石蒜碱的工艺进行优化,并用阳离子交换树脂分离石蒜碱。以纤维素酶与果胶酶的水溶液为提取溶剂,采用L9(34)正交试验考察了酶解p H、酶加入量、酶解时间和酶解温度等影响因素,以石蒜碱得率为指标,得最优提取工艺为:料液比1∶10,p H 4.5,酶添加量4%,酶解温度50℃,提取时间2.0 h,石蒜碱得率为0.1750%。D-001树脂纯化条件为:上样液p H为2,以3 BV/h流速上样,以含1.5 mol/L氨水的70%乙醇洗脱,流速为3 BV/h,初步分离后石蒜碱含量为15.28%。研究结果可为石蒜碱工业化生产提供参考。     

纤维素酶-乙醇协同提取黄芩总黄酮

以黄芩总黄酮的得率为指标,比较了乙醇回流提取、酶-缓冲水溶液提取、纤维素酶-乙醇提取等方法对黄芩总黄酮提取的影响,发现纤维素酶对细胞壁的水解和乙醇溶液对黄酮类物质的浸出产生了协同效应。采用单因素实验法,优化了纤维素酶-乙醇协同提取黄芩总黄酮的工艺条件。结果表明,乙醇体积分数50%,提取温度50℃,提取时间6 h,加酶量50U/g(干原料),液固比15时,纤维素酶-乙醇回流法提取黄芩总黄酮的得率达19.85%,较单一的乙醇回流法提取提高了1.38%。纤维素酶-乙醇回流法可用于黄芩总黄酮的提取。     

阶梯生物催化协同超声提取葫芦巴中薯蓣皂苷的工艺研究

研究响应面法优化阶梯生物催化协同超声提取葫芦巴中薯蓣皂苷的工艺。以葫芦巴中薯蓣皂苷提取量为考察指标,通过单因素试验及响应面试验设计,探讨依次加入纤维素酶和果胶酶复合酶制剂、糖化酶的使用量、酶解温度、pH值、酶解时间对薯蓣皂苷提取量的影响,优化阶梯生物催化协同超声提取葫芦巴中薯蓣皂苷的工艺条件。结果显示,薯蓣皂苷在最佳提取条件下的提取量为23.04 mg/g,比直接超声提取增加了33.88%,表明阶梯生物催化协同超声法是一种高效、简便的从葫芦巴中提取薯蓣皂苷的方法。     

酶解法提取纯化虎杖提取物中自藜芦醇的工艺研究

本文对虎杖提取物中虎杖苷的酶解条件及苷元白藜芦醇的提取纯化工艺进行研究,以样品中自藜芦醇的含量为指标,对纤维素酶、β-葡萄糖苷酶、复合酶进行筛选,结果表明以复合酶的水解效率最高:采用正交实验对影响复合酶酶解的因素:加酶量、温度、酶解时间进行考察;并对酶解后提取物中自藜芦醇的提取纯化工艺进行研究.得出如下较理想的酶解条件和提取纯化工艺:虎杖提取物,加水(pH 5)10倍,加20%的复合酶,于50℃保温24 h;酶解后的提取物经水、乙醇-水、碱溶液分步溶解沉淀,得白藜芦醇粗品,含量可达65%,工艺稳定可行.     

海藻酸钠固定化β-葡萄糖苷酶的研究

以海藻酸钠为载体,研究了β-葡萄糖苷酶固定方法及其条件,并利用固定化β-葡萄糖苷酶进行了酶解试验。结果表明,采用交联-包埋方式,在海藻酸钠质量分数3．5％、给酶量100U／g载体、戊二醛体积分数1％、氯化钙质量分数2％的条件下固定β-葡萄糖苷酶2h,可以获得较佳的固定化效果。其固定率达到65％,重复分批利用20次仍能保持90％以上的酶解得率。利用固定化β-葡萄糖苷酶连续酶解纤维二糖时,在不同进料速度下有着不同的催化效率,当进料速度为1．5mL／min、1．0mL／min时,酶解得率分别达到96,7％和99．0％;与木霉纤维素酶协同水解纤维素时,在β-葡萄糖苷酶总酶活与滤纸酶活之比为0．5（FPA为2．0U／mL）的条件下,酶解滤纸纤维素和微晶纤维素60h的得率比单独采用木霉纤维素酶分别增加了20．4％和29．3％。研究结果对于解决酶法水解纤维资源得率低、酶使用成本高这一关键问题提供了一种有效的方法。     

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.