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尿苷二磷酸葡萄糖(UDPG)是一种重要的糖类物质合成前体.生物法合成具有低成本、无污染和高立体选择性等传统化学法不具备的优势.利用纯酶催化的生物法以基于Leloir途径改进的一锅法、蔗糖合酶催化的两步法以及糖合成反应可逆催化等产UDPG,实现了UDPG的高产.全细胞催化法利用稳定的胞内酶系产UDPG,胞内生成的UDPG作为底物直接参与产物的催化合成,可行性高且成本更低.综述了酶法和全细胞催化法合成UDPG这两种最主要生物法的研究进展. 相似文献
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由于氟原子的特殊性质,化合物中引入氟原子可显著改变其物理化学性质。因此,氟原子在药物中的应用越来越广。此外,80%药物分子结构属于手性分子。其中,氟代手性醇常见于手性药物结构中,该类结构的合成方法研究具有重要的意义。不对称还原含氟酮是合成此结构的常见方法。与化学还原方法相比,生物催化还原具有对映选择性强、产率高和易于分离纯化等优点。生物催化,特别是酶催化还原含氟酮类化合物成为手性药物合成领域的研究热点。本文从纯化酶催化和全细胞催化两个方面,综述了近年来含氟酮生物催化还原合成氟代手性醇的研究进展,并分析总结了氟代对酮生物催化还原的影响,最后对生物催化还原法未来的发展进行了展望。 相似文献
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纳米粒子具有独特的光、电和催化性质;生物物质具有识别、催化和抑制的特性;纳米粒子连接生物分子从而合成了具有生物上的电、光性质的纳米粒子—生物分子复合体。本文介绍了纳米粒子-生物分子复合体系的合成,以及这些纳米粒子—生物分子复合体在生物医学领域的应用及研究进展。 相似文献
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手性生物催化是利用生物催化剂对手性分子构型的识别能力进行选择性催化的新型物质加工过程,具有催化效率高、选择性强和反应条件温和等优势。近十年来,生物催化技术快速崛起,树立了多个大品种原料药过程替代的成功范例,成为手性医药化学品绿色制造不可或缺的重要工具。笔者分析了生物催化商业和学术发展的新动向,并结合笔者在手性药物生物催化合成的产业化开发实践,指出了今后的发展方向。 相似文献
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Norii T 《Biological trace element research》2012,146(2):207-212
During deficient zinc intake, rats are liable to suffer zinc deficiency under the following conditions: higher protein diet,
diet containing higher quality (higher nutritive value) protein, and higher dietary intake. This suggests that a higher protein
nutritional status (rapid increase in body protein) in rats leads to a lower zinc nutritional status (higher zinc requirement).
In contrast, it is expected that a lower protein nutritional status (lowered body protein biosynthesis) is not liable to result
in a lower zinc nutritional status. Therefore, the effects of protein biosynthesis inhibitors on zinc status were studied.
Actinomycin D and cycloheximide were administered to rats under a marginally zinc-deficient condition. The growth of rats
was depressed and serum and femur zinc concentrations were increased by administration of protein biosynthesis inhibitors.
The carcasses of rats administered protein synthesis inhibitors had a higher zinc/protein ratio than those of the respective
pair-fed (calorically equivalent to the zinc-deficient group) rats. Results suggest that zinc deficiency in rats is mainly
alleviated by decreased food intake with administration of protein synthesis inhibitors. Furthermore, protein biosynthesis
inhibition alone alleviated zinc deficiency. 相似文献
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The effect of orotic acid on pulmonary regeneration has been studied in mature rats after left-sided pneumonectomy. A complex morphometric analysis of the pulmonary parenchyma during the process of compensatory-hypertrophic rearrangement has been carried out; mitotic activity of cells in the interalveolar septae, peculiarities of DNA synthesis and those of enzymatic status in lymphocytes of the peripheral blood have been determined. As the investigations have demonstrated, the administration of orotic acid during the postoperative period contributes to a more complete regeneration of the lung volume, alveolar surface, results in formation of new alveoli, prevents the development of morphologic long-term decompensation following pneumonectomy. Activation of the alveolar cells proliferation and increased DNA synthesis are the main stimulating effects of orotic acid. Certain correlative connections are revealed between the course of pulmonary regenerative processes and the enzymic status of circulating lymphocytes. 相似文献
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通过分析一氧化氮(nitric oxide,NO)、活性氧(reactive oxygen species,ROS)和干旱胁迫对小麦根氧化还原状态和叶片脱落酸(abscisic acid,ABA)积累的影响,探讨了干旱胁迫下NO和H2O2调节ABA合成的可能机制。结果表明:干旱胁迫处理初期小麦根还原型谷胱甘肽含量降低、抗氧化酶活性发生振荡变化,细胞氧化还原状态向氧化型转变。NO和H2O2能模拟干旱胁迫的作用使细胞状态向氧化型转变,还可以使小麦叶片ABA积累量上升。干旱胁迫下NO和H2O2对ABA合成的调节作用可能是通过调节细胞氧化还原状态进行。 相似文献
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Peptide based drugs are now a day fascinating application areas. This brief review focuses on the history of peptides, synthesis of peptides, their therapeutic applications and the current status of peptides in the market. 相似文献
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The metabolism of GABA and other amino acids was studied in the substantia nigra, the hippocampus and the parietal cortex of rats following microinjections of GAMMA-vinyl-GABA during status epilepticus induced by lithium and pilocarpine. GABA metabolism showed striking regional variations. In controls, both GABA concentration and rate of GABA synthesis were highest in the substantia nigra and lowest in cortex, as expected. In substantia nigra, status epilepticus resulted in a 2 1/2 fold decline in the rate of GABA synthesis and in a 307% increase in the turnover time of the GABA pool. In hippocampus, the rate of GABA synthesis was not altered significantly, but the turnover time of the GABA pool was 284% of controls, and the size of that pool increased to 208% of controls. By contrast, in cortex, where seizure activity is limited in this model, the rate of GABA synthesis increased to 230% of controls while pool size and turnover time did not change. Aspartate concentration decreased in all three brain regions. These data suggest that the observed reduction of the rate of GABA synthesis in substantia nigra could play a key role in seizure spread in this model of status epilepticus.Special Issue dedicated to Claude Baxter. 相似文献
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Seedlings of Celosia plumosa under prolonged irradiation with far red light synthesize chlorophyll α and betaxanthin. Levulinic acid and 2,4-dinitrophenol, inhibitors of chlorophyll synthesis and cyclic photophosphorylation respectively, reduce betaxanthin synthesis. Pigment formation is also inhibited by actinomycin-D and puromycin, but is unaffected by 3-(3,4-dichlorophenyl)-1,1-dimethylurea, an inhibitor of noncyclic photophosphorylation. These findings are evidence of the involvement of photosynthesis through cyclic photophosphorylation, in the far red HER associated with betaxanthin synthesis. Under continuous far red seedlings of Amaranthus tricolor synthesize only chlorophyll α. Lack of betacyanin formation is ascribed to the inactive status of the genes involved in the pigment synthesis. 相似文献
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Ectopic expression of an amino acid transporter (VfAAP1) in seeds of Vicia narbonensis and pea increases storage proteins
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Rolletschek H Hosein F Miranda M Heim U Götz KP Schlereth A Borisjuk L Saalbach I Wobus U Weber H 《Plant physiology》2005,137(4):1236-1249
Storage protein synthesis is dependent on available nitrogen in the seed, which may be controlled by amino acid import via specific transporters. To analyze their rate-limiting role for seed protein synthesis, a Vicia faba amino acid permease, VfAAP1, has been ectopically expressed in pea (Pisum sativum) and Vicia narbonensis seeds under the control of the legumin B4 promoter. In mature seeds, starch is unchanged but total nitrogen is 10% to 25% higher, which affects mainly globulin, vicilin, and legumin, rather than albumin synthesis. Transgenic seeds in vitro take up more [14C]-glutamine, indicating increased sink strength for amino acids. In addition, more [14C] is partitioned into proteins. Levels of total free amino acids in growing seeds are unchanged but with a shift toward higher relative abundance of asparagine, aspartate, glutamine, and glutamate. Hexoses are decreased, whereas metabolites of glycolysis and the tricarboxylic acid cycle are unchanged or slightly lower. Phosphoenolpyruvate carboxylase activity and the phosphoenolpyruvate carboxylase-to-pyruvate kinase ratios are higher in seeds of one and three lines, indicating increased anaplerotic fluxes. Increases of individual seed size by 20% to 30% and of vegetative biomass indicate growth responses probably due to improved nitrogen status. However, seed yield per plant was not altered. Root application of [15N] ammonia results in significantly higher label in transgenic seeds, as well as in stems and pods, and indicates stimulation of nitrogen root uptake. In summary, VfAAP1 expression increases seed sink strength for nitrogen, improves plant nitrogen status, and leads to higher seed protein. We conclude that seed protein synthesis is nitrogen limited and that seed uptake activity for nitrogen is rate limiting for storage protein synthesis. 相似文献