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脂肪酸去孢和酶的结构与催化特性研究进展 总被引:4,自引:0,他引:4
脂肪酸去饱和酶 (desaturase)能将脂肪酸链上的 C- C单键转化为 C=C双键 [1] ,这类酶催化的反应叫作去饱和反应 .脂肪酸去饱和酶的分布很广泛 ,存在于被检测的所有生命体中 ,除了某些细菌如 Escherichia Coli等 .甘油酯中脂肪酸的不饱和度对生物膜的正常功能影响很大[2 ] .在生理温度下 ,极性甘油酯如果只含有饱和脂肪酸 ,则不能形成生物膜基本的脂双层结构 .引入适当数目的双键 ,可以降低生物膜甘油酯由固体转变为液晶体所需的温度 ,从而提供生物膜必需的流动性 .而膜的流动性对某些膜结合酶的活性是必要的 .脂肪酸去饱和酶分 3类[3] :… 相似文献
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报道了含△6去饱和酶的深黄被孢霉菌丝提取物催化亚油酸合成γ-亚麻酸,研究了辅酶,温度,时间等对γ-亚麻酸合成的影响。结果表明,反应温度降低,γ-亚麻酸的产率提高,在10℃以下,γ-亚麻酸的产率达到最大值;苹果酸盐对该反应有明显促进,γ-亚麻酸的产率随体系pH增加而增加。且在pH=7-8时产率较高;该反应需在分子氧存在下进行;NADPH,ATP和CoA是该反应的必需辅酶。在优化的反应条件下,γ-亚麻酸的疸这到.21mg/mL。 相似文献
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Δ6 去饱和酶催化合成γ-亚麻酸 总被引:2,自引:0,他引:2
报道了含△6去饱和酶的深黄被孢霉菌丝提取物催化亚油酸合成γ-亚麻酸.研究了辅酶、温度、时间等对γ-亚麻酸合成的影响.结果表明,反应温度降低,γ-亚麻酸的产率提高.在10℃以下.γ-亚麻酸的产率达到最大值;苹果酸盐对该反应有明显促进作用.γ-亚麻酸的产率随体系pH增加而增加,且在pH=7~8时产率较高;该反应需在分子氧存在下进行;NADPH,ATP和CoA是该反应的必需辅酶.在优化的反应条件下,γ-亚麻酸的产量达到0.21mg/mL。 相似文献
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化学修饰改进酶的催化特性研究进展 总被引:1,自引:1,他引:1
酶是一种高效生物催化剂.在常温常压和中性介质中,酶能够催化许多化学方法难以完成的反应,且酶催化效率高、专一性强(可减少或避免副反应),符合将废弃物控制在最小限度、实现绿色化学的要求.尤其酶在催化有机相中的反应取得成功后,其用途更加广泛.但目前酶在工业生产中的应用并不十分普遍,其主要原因是酶对热、酸、碱、氧化剂、有机溶剂和重金属离子的稳定性差,已开发的酶的种类有限,工业化的酶催化工艺与化学工艺相比仍有许多问题亟待解决.这促使科学家们不断寻找新的酶,或开发新的方法以改变、提高原有酶的性质,目前已开发出一些成功… 相似文献
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血红蛋白的过氧化物酶催化特性研究 总被引:18,自引:6,他引:18
探讨了用血红蛋白(Hb)作为辣根过氧化物酶(HRP)的替代物,用于率H2O2氧 化对甲基酚的反应体系,研究了血红蛋白的过氧化物酶特征及其酶催化动力学特性 。稳态速率法测定了米氏常数(Km)、米氏速率(Vm)及反应级数等动力学参数。讨 论了对甲基酚作为血红蛋白的氢供体底物的酶催化反应机理,确立了反应速率方程 。实验比较发现血红蛋白作为过氧化物酶(HRP)的替代物,其催化活性比氯化血 红素(Hemin),β-环糊精-氯化血红素(β-CD-Hemin)等过氧化物模拟酶要高。 相似文献
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Stefanie Pleik Bernhard Spengler Thomas Schäfer Dieter Urbach Steven Luhn Dieter Kirsch 《Journal of the American Society for Mass Spectrometry》2016,27(9):1565-1574
GC-MS investigations were carried out to elucidate the aging behavior of unsaturated fatty acids in fingerprint residues and to identify their degradation products in aged samples. For this purpose, a new sample preparation technique for fingerprint residues was developed that allows producing N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA) derivatives of the analyzed unsaturated fatty acids and their degradation products. MSTFA derivatization catalyzed by iodotrimethylsilane enables the reliable identification of aldehydes and oxoacids as characteristic MSTFA derivatives in GCMS. The obtained results elucidate the degradation pathway of unsaturated fatty acids. Our study of aged fingerprint residues reveals that decanal is the main degradation product of the observed unsaturated fatty acids. Furthermore, oxoacids with different chain lengths are detected as specific degradation products of the unsaturated fatty acids. The detection of the degradation products and their chain length is a simple and effective method to determine the double bond position in unsaturated compounds. We can show that the hexadecenoic and octadecenoic acids found in fingerprint residues are not the pervasive fatty acids Δ9-hexadecenoic (palmitoleic acid) and Δ9-octadecenoic (oleic acid) acid but Δ6-hexadecenoic acid (sapienic acid) and Δ8-octadecenoic acid. The present study focuses on the structure identification of human sebum-specific unsaturated fatty acids in fingerprint residues based on the identification of their degradation products. These results are discussed for further investigations and method developments for age determination of fingerprints, which is still a tremendous challenge because of several factors affecting the aging behavior of individual compounds in fingerprints. 相似文献
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唾液酸酶和唾液酸糖基转移酶在生物体内许多重要的生理过程中发挥着不可或缺的作用.一般而言,唾液酸酶可以断裂糖缀合物末端与唾液酸残基相连接的糖苷键而水解唾液酸糖缀合物;唾液酸糖基转移酶以CMP-Neu5Ac为底物将唾液酸残基转移至新的糖基受体上.综述了与唾液酸相关的酶的分类、结构与催化反应机理;唾液酸酶和唾液酸糖基转移酶催化反应在有机合成中的应用;以及唾液酸酶的检测方法.对未来与唾液酸相关的酶的研究与应用进行了展望. 相似文献
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分子磁学主要研究无机配合物以及有机自由基的电子结构和磁性之间的关系。近些年发展起来的分子纳米磁体可以在单分子尺度上实现磁双稳态,独立作为一个磁功能单元,可能突破尺寸对传统磁性材料的制约,有望实现超高密度磁存储。分子纳米磁体中清晰的量子态也为量子退相干研究提供了化学调控的手段,这将为量子计算机提供物质基础。本文简要介绍了分子纳米磁体的概念和特征,并对研究进展进行了简要综述。 相似文献
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Summary. Fatty acid oxidation is usually thought of as being a preferred ATP source during sepsis, as shown by the decrease in respiratory quotient in septic patients and animals. However, fatty acid oxidation may be impaired relative to circulating triglyceride levels, resulting in increased cycling between triglycerides and non-esterified fatty acids. The rate of fatty acid oxidation is critically dependent on the stage of sepsis. Carnitine may be depleted during sepsis by a combination of muscle wasting, erythrocyte haemolysis, decreased tissue uptake, reduced kidney reabsorption of free carnitine, and increased excretion of acyl-carnitines. Whether there may be any beneficial effects of carnitine supplementation during sepsis, is, as yet, uncertain. 相似文献
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Fatty acid oxidation is usually thought of as being a preferred ATP source during sepsis, as shown by the decrease in respiratory quotient in septic patients and animals. However, fatty acid oxidation may be impaired relative to circulating triglyceride levels, resulting in increased cycling between triglycerides and non-esterified fatty acids. The rate of fatty acid oxidation is critically dependent on the stage of sepsis. Carnitine may be depleted during sepsis by a combination of muscle wasting, erythrocyte haemolysis, decreased tissue uptake, reduced kidney reabsorption of free carnitine, and increased excretion of acyl-carnitines. Whether there may be any beneficial effects of carnitine supplementation during sepsis, is, as yet, uncertain. 相似文献
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本文介绍近年来,结构型有机高分子磁性体研究所取得的进展,包括磁性体简单的设计原理、含金属原子和不含金属原子的磁性体、磁性体模型的制备以及可能应用的前景。 相似文献
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双波长分光光度法的研究进展 总被引:7,自引:0,他引:7
文中对双波长分光光度法在近十年来的研究进展作了评述。内容分为4部分:①常规双波长分光光度法;②标准加入法-双波长分光光度法;③计算双波长分光光度法及④双峰双波长分光光度法,引述文献23篇。 相似文献
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Otopkova K. V. Esipovich A. L. Kanakov E. A. Charykova T. A. Baydachenko V. E. Ryabova T. A. 《Kinetics and Catalysis》2022,63(6):666-675
Kinetics and Catalysis - The activity and stability of cation-exchange resins in fatty acid esterification with methyl alcohol have been studied. The cation-exchange resins have been characterized... 相似文献