奎尼酸的生物合成与应用

奎尼酸是一种具有极高价值的精细化工产品和医药中间体,在医药、食品、化工等行业均有广泛的应用价值。奎尼酸广泛存在于多种植物中,其咖啡酰类衍生物在抗病毒、治疗心血管疾病等研究中得到越来越多的关注和应用。目前获得奎尼酸的方法主要有4种,即植物提取法、化学合成法、酶工程法和微生物发酵法。随着分子生物学的不断发展,结合现代生物技术,应用基因工程方法,必将成为获得奎尼酸的重要途径。本文综述奎尼酸的分布、生物合成及其应用。     

基于定量PCR技术探讨紫杉醇生物合成的限速步骤

次生代谢产物牛物合成受到发育和诱导的调控,本实验研究了组织分化和诱导处理对紫杉醇生物合成的影响,并采用定量PCR技术分析了紫杉醇生物合成不同阶段关键酶基因的动态表达特征。结果表明。紫杉醇主要分布在中国红豆杉（Taxus chinensis）树皮和根皮组织中,针叶内含量很少,催化紫杉醇功能官能团连接的关键酶摹因也主要定位在树皮和根皮组织巾;茉莉酸甲酯（MJ）和真菌诱导子F5分别提高了中国红豆杉悬浮培养细胞HG-1紫杉醇得率8倍和10倍,同时有效诱导紫杉醇生物合成基因的表达。发现催化紫杉醇侧链连接的基因与紫杉醇生物合成早正相关。结果表明。紫杉醇生物合成的限速步骤是催化功能官能团连接的步骤。     

Instability of anthocyanin accumulation inVitis vinifera L. var. Gamay Fréaux suspension cultures

The inherent instability of metabolite production in plant cell culture-based bioprocessing is a major problem hindering its commercialization. To understand the extent and causes of this instability, this study was aimed at understanding the variability of anthocyanin accumulation during long-term subcultures, as well as within subculture batches, inVitis vinifera cell cultures. Therefore, four cell line suspensions ofVitis vinifera L. var. Gamay Fréaux, A, B, C and D, originated from the same callus by cell-aggregate cloning, were established with starting anthocyanin contents of 2.73±0.15, 1.45±0.04, 0.77±0.024 and 0.27±0.04 CV (Color Value)/g-FCW (fresh cell weight), respectively. During weekly subculturing of 33 batches over 8 months, the anthocyanin biosynthetic capacity was gradually lost at various rates, for all four cell lines, regardless of the significant difference in the starting anthocyanin content. Contrary to this general trend, a significant fluctuation in the anthocyanin content was observed, but with an irregular cyclic pattern. The variabilities in the anthocyanin content between the subcultures for the 33 batches, as represented by the variation coefficient (VC), were 58, 57, 54, and 84% forV. vinifera cell lines A, B, C and D, respectively. Within one subculture, the VCs from 12 replicate flasks for each of 12 independent subcultures were averaged, and found to be 9.7%, ranging from 4 to 17%. High- and low-producing cell lines, VV05 and VV06, with 1.8-fold differences in their basal anthocyanin contents, exhibited different inducibilities tol-phenylalanine feeding, methyl jasmonate and light irradiation. The low-producing cell line showed greater potential in enhanced the anthocyanin production.     

植物萜类合酶研究进展

随着植物中许多有价值的萜类化合物被发现和应用于人类生活 ,萜类生物合成途径的研究倍受重视。萜类合酶催化单萜、倍半萜和二萜生物合成 ,即分别催化GPP、FPP和GGPP形成单萜、倍半萜和二萜。本文叙述了近年来在植物萜类合酶催化机理、克隆策略和萜类生物工程的研究进展     

盐单胞菌属BYS1四氢嘧啶合成基因ectABC克隆及其盐激表达

利用SEFA-PCR技术从中度嗜盐菌Halomonassp.BYS-1总DNA中克隆了四氢嘧啶合成基因ectABC及其上游序列(GenBank accession number DQ017757);OMIGA软件分析结果显示ectA、ectB、ectC位于同一个操纵子上,大小分别为573bp1、251bp和387bp,预测编码的DAT(L-二氨基丁酸转氨酶)、DAA(L-二氨基丁酸乙酰转移酶)和ES(四氢嘧啶合酶)大小分别为21.1kDa(191 amino acid)、45.7kDa(417 amino acid)和14.5kDa(129 amino acid);将包含ectABC基因及其上游1000bp序列的片段克隆到pUC19中并转化E.coliDH5α,转化子E.coli(pUC19ECT)能够在盐激条件下合成四氢嘧啶,但其耐盐能力没有得到显著改善。     

生物法合成3-羟基丙酸的研究进展

从3-羟基丙酸的性质出发,介绍了生物法合成3-羟基丙酸以及它在生物体内的五种代谢途径,此外还简要介绍了3-羟基丙酸在合成生物聚酯、抗植物病虫害上的一些应用。     

两个水稻GDP-甘露糖-3’，5＇-异构酶基因特征及表达模式的研究

GDP-甘露糖-3’,5’-异构酶（GME）可以催化GDP-甘露糖转化为左旋GDP-半乳糖,该反应对于高等植物体内抗坏血酸的合成是非常重要的．但目前在分子水平上还没有对GME基因进行研究的报道．通过逆转录PCR（RT-RCR）技术从水稻成熟叶片中克隆到两个GME基因的cDNA序列,并与其他植物物种中的GMEs进行比对,结果显示,GME基因在所有植物物种中高度保守,尽管进化树分析表明单子叶植物GMEs和双子叶植物GMEs在进化上相互独立．同时,分析这两个水稻GME基因的剪切模式揭示了二者也存在高度相似性．采用半定量RT-PCR技术对两个GME基因在不同组织和不同胁迫条件下的表达模式进行研究表明,OsGME1基因在冷胁迫条件下表达水平上调,这和先前水稻冷胁迫蛋白质组学研究的结果是一致的．而OsGME2和OsGME1基因在用赤霉素处理条件下表达水平均下调,暗示赤霉素可能通过调节GME基因的表达来调控植物体内的抗坏血酸合成．     

Cellulose-bound Peptide Arrays: Preparation and Applications

Spatial organization of metabolic enzymes may represent a general cellular mechanism to regulate metabolic flux. One recent example of this type of cellular phenomenon is the purinosome, a newly discovered multi-enzyme metabolic assembly that includes all of the enzymes within the de novo purine biosynthetic pathway. Our understanding of the components and regulation of purinosomes has significantly grown in recent years. This paper reviews the purine de novo biosynthesis pathway and its regulation, and presents the evidence supporting the purinosome assembly and disassembly processes under the control of G-protein-coupled receptor (GPCR) signaling. This paper also discusses the implications of purinosome and GPCR regulation in drug discovery.     

放线菌天然产物糖基化改造研究进展

放线菌可以产生结构多样的天然产物, 其中包括很多重要的抗菌和抗肿瘤药物。糖基化修饰在天然产物中广泛存在, 糖基侧链的变化往往会影响天然产物的生物活性。本文综述了放线菌来源天然产物糖基化改造的研究进展。糖基侧链改造的方法主要分为体内基因工程和体外酶学法。运用这两种方法已经成功对多种天然产物进行了糖基侧链改造, 获得了大量带有新糖基修饰的天然产物, 其中有些生物活性得以提高。天然产物糖基侧链改造为新药开发提供了一个重要的途径。     

In vitro antifungal activity and mode of action of selected polyphenolic antioxidants on Botrytis cinerea

Six selected antioxidants (catechin, quercetin-3-galactoside, cyanidin-3-glucoside, pelargonidin-3-glucoside, ellagic and gallic acids) were evaluated in vitro for their antifungal activities and mode of action on Botrytis cinerea Pers., one of the most important pathogens of strawberries. Inhibitory effects were found for all the tested antioxidants, but varied at different fungal developmental stages. Catechin and quercetin-3-galactoside showed linear inhibitory effects on germ tube elongation, with the highest suppression ratios of 54.8% and 58.8% respectively. No significant effect was found on spore germination between treatments and control. Gallic acid showed very strong and linear inhibition on spore germination (r = ?0.95), but the effect diminished after spore germination. Cyanidin-3-glucoside and pelargonidin-3-glucoside provided effective control on the fungi as concentrations increased. The arresting effect of ellagic acid on development of B. cinerea was quadratic. Ellagic acid inhibited germ tube elongation and mycelial growth at its highest and lowest concentrations, while no effects were observed at its medium concentration used in this study.