用终止剂改进超氧化物歧化酶邻苯三酚测活法

以二硫苏糖醇(DTT)或L-抗坏血酸(Vit C)为终止剂改进的经典邻苯三酚法测定超氧化物歧化酶(SOD)活性.反应体系:50mmol/L邻苯三酚,pH8.20,总体积9ml,25℃,加一滴DTT(100mmol/L)或Vit C(5%),约50μl,终止自氧化反应.终止后,反应体系的420nm光吸收在lh内保持恒定.终止剂法的邻苯三酚自氧化率及酶活测定灵敏度与经典法相近,一个酶活单位相当于纯SOD 100μg/L.     

超氧化物歧化酶两种邻苯三酚自氧化测定活力方法的比较

在同一反应条件下,以酵母SOD为原料,对2种邻苯三酚自氧化测定SOD的方法进行了比较,实验结果表明325 nm法测定的酶活力单位与420 nm法测定的酶活力单位的比值约为2.7,考察了不同浓度邻苯三酚对SOD活力的影响。     

石榴叶总黄酮提取工艺及体外抗氧化性研究

目的:研究石榴叶总黄酮的提取工艺及体外抗氧化性.方法:利用L9(34)正交设计实验,探讨了提取条件对石榴叶中总黄酮提取量的影响,并采用Fenton体系和邻苯三酚自氧化法评价了该提取物的体外抗氧化能力.结果:最佳提取工艺条件为:80%的乙醇、料液比为1:15、提取温度为60℃、提取时问4h,即A3B1 C3D2,此条件下提取的总黄酮含量为0.4281%;石榴叶总黄酮清除·OH和抑制邻苯三酚自氧化能力均略高于VC.结论:实验表明石榴叶总黄酮具有较强的体外抗氧化活性.     

花蚬酶解物清除羟自由基作用研究

探讨了不同蛋白酶酶解花蚬蛋白所得酶解物对Fenton体系产生的羟自由基(.OH)的清除效果,然后进行Sephadex G-25凝胶柱分离酶解产物中的抗氧化活性肽,并测定活性肽相对分子质量分布。结果表明:木瓜蛋白酶在50℃、酶解30 min、pH=7.5、酶质量分数0.15%、m(底物)∶m(水)=1∶2的水解条件下,酶解物对羟自由基的清除效果最佳,清除率为86.9%;胰蛋白酶在温度55℃、酶解时间85 min、pH=8.0、酶质量分数0.30%、m(底物)∶m(水)=1∶2的水解条件下,酶解物对羟自由基清除效果最佳,清除率为89.5%。木瓜蛋白酶酶解物在最大洗脱峰时,清除率为84.73%,在最大峰处酶解物中活性肽的相对分子质量为5.68×103;胰蛋白酶酶解物有两个洗脱峰,在最大洗脱峰处分离组分对羟自由基的清除率很低,在较小洗脱峰处,其清除率为88.49%,该峰处活性肽的相对分子质量为1.165×104。     

几种蛋白酶对文蛤肉的酶解工艺条件研究

以文蛤为原料,水解度为指标,从胰蛋白酶,木瓜蛋白酶,胃蛋白酶和风味蛋白酶中选出水解效果较好的胰蛋白酶和木瓜蛋白酶.并通过实验确定了胰蛋白酶,木瓜蛋白酶单酶水解及两者组合复合酶解文蛤肉的最佳工艺.结果表明:复合水解效果最佳.最佳工艺:先添加胰酶6000 u/g(原料),水解温度50℃,固液比1:3(V/W),pH 8.0,在此条件下水解6 h;然后改变条件,温度55℃,pH 5.5,底物浓度1:3(V/W),添加木瓜蛋白酶2000 u/g(原料),在此条件下水解2 h.通过实验验证,胰蛋白酶和木瓜蛋白酶组合在该条件下对文蛤肉蛋白具有较好的水解效果,其水解度为28.15%.     

一种SOD的测活方法——邻苯三酚自氧化法的改进

超氧化物歧化酶(SOD)是在医疗上具有广泛应用前景的酶。它的测活方法很多,一般是根据SOD具有抑制O_2介导的反应的能力这一原理而建立的。邻苯三酚自氧化法是其中较为简便的一种,本文对这种方法做了下述改进。材料与方法 1.仪器 M750UVIS-A型微量紫外可见分光光度计和日本岛津双光束双波长自动记录分光光度计。 2.试剂 SOD(上海生化所东风试剂厂产品),其它试剂均为分析纯。 3.邻苯三酚自氧化速率的测定取4.5ml100mM缓冲液(见表1),4.2ml蒸馏水,混匀     

邻苯三酚-碳酸盐缓冲液化学发光体系的研究

用化学发光法研究了邻苯三酚碱性自氧化产生O₂^-_·的发光行为.通过对测定条件的研究, 得出最佳测定方案.改进后的方法不需使用发光剂Luminol, 所用试剂价廉易得, 且方法稳定, 重现性好.此法灵敏度远高于邻苯三酚自氧化的其他文献报道法.     

高效液相色谱法测定可口革囊星的ACE活性

目的利用高效液相色谱法测定可口革囊星虫酶解物中具有抑制血管紧张素转化酶(ACE)活性的活性肽。方法用HPLC测定血管紧张素转换酶抑制肽活性,在该色谱条件下,可通过测定由ACE水解马尿酰组氨酰亮氨酸后产生的马尿酸峰面积或含量得到酶解液的活性。结果酶解物在质量浓度为0.48mg/ml时对ACE的抑制率为17.62%。结论可口革囊星虫蛋白经碱性蛋白酶水解后得到的酶解物活性较高。     

白蜡虫卵蛋白酶解工艺的研究

本项目对白蜡虫(Ericerus pela)卵蛋白的酶解工艺进行了研究。通过正交试验确定木瓜蛋白酶为适宜的水解用酶,最佳用量为1.5%;酶解条件为酶解温度50℃,酶解pH值9.0,酶解时间24 h,原料与水比例为1∶20;试验结果还表明原料在酶解前经过预处理,蛋白水解率可提高20.7%,预处理条件为原料在20倍的1 mol/L盐酸溶液中,80℃恒温加热30 min;在确定的最佳条件下对白蜡虫卵进行预处理和酶解,蛋白水解率可达58.4%。     

双酶法制备螺旋藻多肽的工艺研究

选用碱性蛋白酶和木瓜蛋白酶结合的双酶法对螺旋藻蛋白进行水解。其中,对木瓜蛋白酶水解螺旋藻蛋白的工艺进行优化。以水解度为指标,研究了酶解时间、酶与底物比、pH和酶解温度4种因素对酶解反应的影响。在此基础上设计了3因素(加酶量、酶解温度和pH)3水平的响应面试验。结果表明碱性蛋白酶水解螺旋藻蛋白的最佳酶解条件为:加酶量4300 U/g,pH 7.0,酶解温度55℃,酶解时间160 min;木瓜蛋白酶的最佳酶解条件为:酶底比为4.5%,酶解温度60℃,pH 6.5,酶解时间210 min。利用碱性蛋白酶和木瓜蛋白酶结合的双酶法制得的多肽水解度可达32.90%,与单酶法相比,水解度明显提高。     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various