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171.
Trompier D Baubichon-Cortay H Chang XB Maitrejean M Barron D Riordon JR Di Pietro A 《Cellular and molecular life sciences : CMLS》2003,60(10):2164-2177
Recombinant nucleotide-binding domains (NBDs) from human multidrug resistance protein MRP1 were overexpressed in bacteria and purified to measure their direct interaction with high-affinity flavonoids, and to evaluate a potential correlation with inhibition of MRP1-mediated transport activity and reversion of cellular multidrug resistance. Among different classes of flavonoids, dehydrosilybin exhibited the highest affinity for both NBDs, the binding to N-terminal NBD1 being prevented by ATP. Dehydrosilybin increased vanadate-induced 8-N3-[-32P]ADP trapping, indicating stimulation of ATPase activity. In contrast, dehydrosilybin strongly inhibited leukotriene C4 (LTC4) transport by membrane vesicles from MRP1-transfected cells, independently of reduced glutathione, and chemosensitized cell growth to vincristine. Hydrophobic C-isoprenylation of dehydrosilybin increased the binding affinity for NBD1, but outsite the ATP site, lowered the increase in vanadate-induced 8-N3-[-32P]ADP trapping, weakened inhibition of LTC4 transport which became glutathione dependent, and induced some cross-resistance. The overall results indicate multiple binding sites for dehydrosilybin and its derivatives, on both cytosolic and transmembrane domains of MRP1.Received 1 May 2003; received after revision 18 June 2003; accepted 24 June 2003 相似文献
172.
173.
银杏叶中黄酮甙类化合物的提取与初步分离 总被引:5,自引:0,他引:5
本文研究了从银杏叶中提取黄酮甙类化合物的工艺条件,对提取到的混合物用薄层层析法进行了分离。结果表明,从银杏叶中提取出的黄酮甙类混合物中可分离出四种以上的纯组分。 相似文献
174.
求解双尺度差分方程的一种新迭代算法 总被引:1,自引:0,他引:1
本文给出了求解双尺度差分方程的新方法。读方法屿已有方法相比具有存储量小和运算速度快等特点。 相似文献
175.
对C+注入α-Al2O3单晶样品的表面残余应力、显微硬度、断裂韧性和注入层破坏临界负荷等力学性能的变化进行了研究.结果表明:C+离子注入Al2O3单晶时,表面层的破碎临界负荷增大.在1×1017C+/cm2时表面产生的残余压缩应力达到最大,而更高剂量的注入使表面层产生非晶化,降低了表面的残余压缩应力.在5×1017C+/cm2注入剂量时,由于表面残余压缩应力和表面非晶化的协同效应使注入层具有较高的表面韧性和表面层耐破碎临界负荷. 相似文献
176.
F. E. Weber J. H. Dyer F. López García M. Werder T. Szyperski K. Wüthrich H. Hauser 《Cellular and molecular life sciences : CMLS》1998,54(7):751-759
The preform of the rabbit sterol carrier protein 2 (pre-rSCP2) was cloned, the uniformly 15N-labelled protein expressed in Escherichia coli and studied by three-dimensional 15N-resolved nuclear magnetic resonance spectroscopy. In spite of its low solubility in aqueous solution of only ∼0.3 mM, sequential
15N and 1H backbone resonance assignments were obtained for 105 out of the 143 residues. From comparison of the sequential and medium-range
nuclear Overhauser effects (NOEs) in the two proteins, all regular secondary structures previously determined in mature human
SCP2 (hSCP2) [Szyperski et al. (1993) FEBS Lett. 335: 18–26] were also identified in pre-rSCP2. Near-identity of the backbone 15N and 1H chemical shifts and 1 : 1 correspondence of 24 long-range NOEs to backbone amide groups in the two proteins show that the
residues 21 – 143 adopt the same globular fold in pre-rSCP2 and mature hSCP2. The N-terminal 20-residue leader peptide of pre-rSCP2 is flexibly disordered in solution and does not observably affect the conformation of the polypeptide segment 21 – 143.
Received 11 May 1998; accepted 15 May 1998 相似文献
177.
本文引入与拓扑空间中S-开集有关的一类新映射.在更一般的映射类中研究S-局部可分空间的映射性质,得到广泛而有用的结果 相似文献
178.
3—氯丙基三甲氧基硅烷的合成 总被引:2,自引:0,他引:2
以三氯硅烷与3-氯丙基丙烯为原料在氯铂酸复合催化剂催化下合成了3-氯丙基三氯硅烷,继而用醇醇解,合成了3-氯丙基三甲氧基硅烷,总收率80%。 相似文献
179.
Marta Michalik Katarzyna Wójcik-Pszczoła Milena Paw Dawid Wnuk Paulina Koczurkiewicz Marek Sanak Elżbieta Pękala Zbigniew Madeja 《Cellular and molecular life sciences : CMLS》2018,75(21):3943-3961
Bronchial asthma is a chronic inflammatory disease in which bronchial wall remodelling plays a significant role. This phenomenon is related to enhanced proliferation of airway smooth muscle cells, elevated extracellular matrix protein secretion and an increased number of myofibroblasts. Phenotypic fibroblast-to-myofibroblast transition represents one of the primary mechanisms by which myofibroblasts arise in fibrotic lung tissue. Fibroblast-to-myofibroblast transition requires a combination of several types of factors, the most important of which are divided into humoural and mechanical factors, as well as certain extracellular matrix proteins. Despite intensive research on the nature of this process, its underlying mechanisms during bronchial airway wall remodelling in asthma are not yet fully clarified. This review focuses on what is known about the nature of fibroblast-to-myofibroblast transition in asthma. We aim to consider possible mechanisms and conditions that may play an important role in fibroblast-to-myofibroblast transition but have not yet been discussed in this context. Recent studies have shown that some inherent and previously undescribed features of fibroblasts can also play a significant role in fibroblast-to-myofibroblast transition. Differences observed between asthmatic and non-asthmatic bronchial fibroblasts (e.g., response to transforming growth factor β, cell shape, elasticity, and protein expression profile) may have a crucial influence on this phenomenon. An accurate understanding and recognition of all factors affecting fibroblast-to-myofibroblast transition might provide an opportunity to discover efficient methods of counteracting this phenomenon. 相似文献
180.