Oyster mushroom (Pleurotus ostreatus) reduces the activity of 3-hydroxy-3-methylglutaryl CoA reductase in rat liver microsomes

The effect of dried oyster mushroom (Pleurotus ostreatus) on cholesterol (C) content in serum, in lipoproteins and in liver, and on the activity of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase in liver microsomes, was studied in male rats (strain Wistar, initial body weight 75 g) fed on low-cholesterol (9 mg/100 g) and high-cholesterol (0.3%) diets. Addition of 5% oyster mushroom to both diets reduced significantly the C-content in serum (by 30%), in very-low- and low-density lipoproteins (in a 11 ratio to the decrease of total serum C) and in liver (by 50%), as well as the activity of HMG-CoA reductase (by more than 30%).     

大肠杆菌巴豆甜菜碱还原酶基因缺失菌株的构建

报道了体外构建caiA基因缺失的带有卡那霉素抗性基因的5．2kb线状DNA分子,以此转化大肠杆菌JM83和BL21(DE3)株,借助于体内DNA同源重组,定向敲除了大肠杆菌中的巴豆甜菜碱还原酶编码基因caiA。经遗传稳定性实验、聚合酶链反应(PCR)以及Southern鉴定,表明所获得的JM83转化子22号和BL21(DE3)转化子4号确为caiA基因缺失突变株;酶活分析结果表明,22号和4号转化子均丧失了巴豆甜菜碱还原酶活性。     

两类脂肪酸合酶中酮酰还原酶的结构、功能和药物开发前景

自然界中脂肪酸合酶（FAS）以FASⅠ和FASⅡ两种形式存在。存在于动物中的FASⅠ是由多活性中心构成的复合酶,存在于植物和细菌中的FASⅡ则是由多个独立蛋白构成的酶体系。FASⅠ和FASⅡ中催化酮酰基团还原的酶有一定同源性,酶催化动力学和酶抑制动力学的性质相似,因分子量过大,目前尚无详细的FASⅠ空间结构信息。通过比较两种类型FAS中酮酰还原酶结构与功能的异同,进一步了解FASⅠ的结构与功能。对两种不同进化程度和存在形式的同源酶进行比较研究,将有得提示复合酶的结构与功能,并得寻找新型特异性蛋白抑制剂,为新药开发提供先导化合物,具有十分重要的理论意义和应用价值。     

An Affordable Accurate Evaluation of the Binding Conformations Predicted by Molecular Docking Studies in Bio-System

正Recently,docking has been widely used to predict the binding-modes of protein-inhibitors,when the crystal complexes structure was absent.Most docking algorithms are able to generate a large number of probable conformations,it,however,is difficult to effectively evaluate these docking poses and identify the most reasonable bindingmode.In the present study,on the basis of the crystallographic data of human 3-hydroxy-3-methylglutaryl coenzyme     

玉米谷胱甘肽还原酶活性测定方法的比较

植物的谷胱甘肽还原酶（ＧＲ） 在氧化胁迫反应中起重要的作用．为了找出测定玉米幼苗ＧＲ 活性最灵敏及最适合的方法，我们采用在２８ ℃／２５ ℃（ 昼／ 夜） 、暗中生长１ ．５ ～４ ．５ ｄ 的玉米幼苗，通过几种测定方法进行比较．结果表明，对于研究玉米幼苗在环境胁迫中ＧＲ 活性的变化，方法２ 是最灵敏、最可行和最实用的．     

红小豆叶片硝酸还原酶测定法的改进

以红小豆资源为材料,采用硝酸还原酶测定试剂盒测定各材料硝酸还原酶含量。实验结果发现:严格按照试剂盒说明操作,普遍存在对照管值与测定管值相差不大,或对照管值大于测定管值的非正常现象。经过诱导硝酸还原酶时间梯度实验、37℃保温时间梯度实验,否认了此现象产生是由酶活性表达过低引起。将对照管中成分进行调整,消除了该现象。经讨论,认为调整后的对照比原对照更为合理。     

春小麦幼苗硝酸还原酶活性与品种抗旱性的关系

报道了PEG溶液渗透胁迫下春小麦幼苗的NR活性及含氮物质的变化,并对NR活性作为评定春小麦品种抗旱性的指标进行了探讨。结果表明,抗旱性强的品种在无胁迫时NR活性一般较低,在胁迫时,酶活下降幅度较小,SI亦较小;抗旱性弱的品种具有相反的特征。说明春小麦幼苗NR活性与品种的抗旱性有着一定的关系。     

钼对葡萄叶片硝酸还原酶活性及生长发育的影响

适量施钼有利于葡萄生长过程中硝酸还原酶活性的提高，缺乏或过量则使其降低，其他微量元素对ＮＲ活性也产生一定影响。由于酶活性的差异也对葡萄的生长发育带来影响。     

Subatomic and atomic crystallographic studies of aldose reductase: implications for inhibitor binding

The determination of several of aldose reductase-inhibitor complexes at subatomic resolution has revealed new structural details, including the specific interatomic contacts involved in inhibitor binding. In this article, we review the structures of the complexes of ALR2 with IDD 594 (resolution: 0.66 Å, IC50 (concentration of the inhibitor that produced half-maximal effect): 30 nM, space group: P2¹), IDD 393 (resolution: 0.90 Å, IC50: 6 nM, space group: P1), fidarestat (resolution: 0.92 Å, IC50: 9 nM, space group: P2¹) and minalrestat (resolution: 1.10 Å, IC50: 73 nM, space group: P1). The structures are compared and found to be highly reproductible within the same space group (root mean square (RMS) deviations: 0.15 0.3 Å). The mode of binding of the carboxylate inhibitors IDD 594 and IDD 393 is analysed. The binding of the carboxylate head can be accurately determined by the subatomic resolution structures, since both the protonation states and the positions of the atoms are very precisely known. The differences appear in the binding in the specificity pocket. The high-resolution structures explain the differences in IC50, which are confirmed both experimentally by mass spectrometry measures of VC50 and theoretically by free energy perturbation calculations. The binding of the cyclic imide inhibitors fidarestat and minalrestat is also described, focusing on the observation of a Cl^- ion which binds simultaneously with fidarestat. The presence of this anion, binding also to the active site residue His110, leads to a mechanism in which the inhibitor can bind in a neutral state and then become charged inside the active site pocket. This mechanism can explain the excellent in vivo properties of cyclic imide inhibitors. In summary, the complete and detailed information supplied by the subatomic resolution structures can explain the differences in binding energy of the different inhibitors.     

突变型大肠杆菌二氢叶酸还原酶基因的合成

利用PCR定点突变技术，以野生型大肠杆菌二氢叶酸还原酶基因为模板，获取3种突变型(Cys85Ser．Cysl51Ser，Cys85／151Ser)二氢叶酸还原酶(DHFR)基因．用限制性内切酶BamH Ⅰ与Pst Ⅰ将3种突变基因片段插入到克隆载体pUC18上，进行蓝白筛选，将筛选的克隆进行DNA序列测定．