共查询到20条相似文献,搜索用时 93 毫秒
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建立了测定食品中天麻素的方法。用水对样品进行超声提取 ,以 ZORBAX SB- C18(5 μm,4 .6× 2 5 0 mm)为分析柱 ,甲醇 - 0 .2 %磷酸溶液为流动相 ,流量 1.0 m L· min- 1 ,检测波长 2 2 1nm。天麻素最低检出限为 0 .6 ng,天麻素进样量在 0 .0 15~ 0 .6 μg范围内呈良好的线性 ,线性关系 r=0 .99993,平均回收率 98.6 % ,RSD=0 .87% (n=6 )。方法简便、快速、稳定、灵敏 ,可作为食品中天麻素的质量控制 相似文献
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青蒿素生物合成研究进展综述 总被引:2,自引:0,他引:2
综述了青蒿素生物合成的研究进展,涉及青蒿素植物组织的培养、生物合成中生理生态因子的影响、生物培养体系的建立及生物合成场所、合成路线、合成关键酶及基因调控等方面的研究,并对青蒿素生物合成的发展前景进行了展望。 相似文献
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中药对黑素生物合成上调作用影响的研究 总被引:1,自引:0,他引:1
通过考察单味中药薄荷、降香和得方中药七宝美髯红方的水提物对酪氨酸酶促黑素生物合成的影响作用,表明:薄荷、降香和复方中药七宝美髯组方提物有促进黑素生物合成的作用,同时紫外光波长对黑素合成上调率的影响更为显著。实验范围内,波长330nm的紫外光使100mg/mL薄荷水提物参与黑素合成物(Ⅰ)的上调率达617%,使100mg/mL降香水提物参与黑素合成物(Ⅱ)的上调率达685%;波长300nm的紫外光使200mg/mL七宝美髯组方水提物参与黑素合成物(Ⅲ)的上调率提高到544%。Ⅰ和Ⅱ在UVB、UVA段均有强吸收;Ⅲ在UVB在有强吸收,但在UVA段的吸收减弱。 相似文献
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安丝菌素(Ansamitocin)是一种微生物来源的美登素类抗生素,具有独特的抗癌活性,其中AP-3在安丝菌素中所占比例最高,是发酵的目标产物,在临床上有靶向治疗乳腺癌的效果,因此具有重要的药用研究价值。但当前AP-3的微生物发酵产量不高,高昂的生产成本制约了其进一步的应用。本文在阐述安丝菌素生物合成及代谢调控机制的基础上,分析讨论了微生物发酵产安丝菌素过程中菌种选育、发酵复杂过程的控制与优化以及下游的分离纯化技术等研究进展。再对未来利用新型诱变技术、合成生物学技术与辅因子工程改造等方法选育高产安丝菌素的工程菌株,以及开发高效创新、低成本的分离纯化工艺进行了展望,以期显著地提高安丝菌素的发酵水平,为工业化安丝菌素的发展奠定坚实的基础。 相似文献
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Kaysser L Tang X Wemakor E Sedding K Hennig S Siebenberg S Gust B 《Chembiochem : a European journal of chemical biology》2011,12(3):477-487
Napsamycins are potent inhibitors of bacterial translocase I, an essential enzyme in peptidoglycan biosynthesis, and are classified as uridylpeptide antibiotics. They comprise an N-methyl diaminobutyric acid, an ureido group, a methionine and two non-proteinogenic aromatic amino acid residues in a peptide backbone that is linked to a 5'-amino-3'-deoxyuridine by an unusual enamide bond. The napsamycin gene cluster was identified in Streptomyces sp. DSM5940 by using PCR probes from a putative uridylpeptide biosynthetic cluster found in S. roseosporus NRRL15998 by genome mining. Annotation revealed 29 hypothetical genes encoding for resistance, regulation and biosynthesis of the napsamycins. Analysis of the gene cluster indicated that the peptide core structure is assembled by a nonlinear non-ribosomal peptide synthetase (NRPS)-like mechanism that involves several discrete single or didomain proteins. Some genes could be assigned, for example, to the synthesis of the N-methyl diaminobutyric acid, to the generation of m-tyrosine and to the reduction of the uracil moiety. The heterologous expression of the gene cluster in Streptomyces coelicolor M1154 resulted in the production of napsamycins and mureidomycins as demonstrated by LC-ESI-MS and MS/MS analysis. The napsamycin gene cluster provides a molecular basis for the detailed study of the biosynthesis of this class of structurally unusual compounds. 相似文献
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在水滑石类催化剂的基础上,引入活性炭载体,使活性组分得到分散,显著提高了催化剂的抗失活能力以及重复使用次数。并结合反应为传质控制的特点,对反应条件进行了优化。 相似文献
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Mycolactone, a polyketide toxin responsible for the extensive tissue destruction seen in Buruli ulcer, is assembled on a modular polyketide synthase (PKS). Despite operating on structurally different intermediates during synthesis, many of the ketoreductase (KR) domains of the mycolactone (MLS) PKS have identical sequences. This suggests that these enzymes might exhibit an unusually high level of substrate promiscuity. However, we show here that when recombinant mycolactone KR domains are tested with a range of surrogate substrates, their specificity closely matches that of KR domains derived from other PKS systems. In addition, our findings reinforce the role of substrate tethering for achieving stereochemical control in modular PKSs by affecting the delicate energetics of ketoreduction. 相似文献
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Dayal Aradhana Harihara Puthran Sreeja Govindasamy Sharmila Chandrasekaran Muthukumaran 《化学工程与技术》2014,37(7):1191-1197
An unconventional aqueous two‐phase system (ATPS) composed of polyethylene glycol (PEG) and sodium carbonate was developed and optimized by employing response surface methodology for separation of Rhizopus niveus lipase. A five‐level central composite design was applied to evaluate the optimal level of three process variables in order to obtain maximum lipase separation. Experimental data were analyzed by regression and a polynomial model was created which was found significant. The maximum partition coefficient was achieved with the system PEG 4000/sodium carbonate. Validation experiments confirmed the high accordance of predicted and experimental results. The optimized ATPS can be applied as a suitable cost‐effective system for lipase extraction. 相似文献