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81.
蛋白分泌作为细胞之间传递信号的途径之一,在微生物生存竞争中也扮演着重要的角色。革兰氏阴性菌可以通过Ⅵ型分泌系统(type Ⅵ secretion system, T6SS)将效应蛋白传递至胞外或原核和真核微生物中,从而介导微生物间的竞争或宿主-细菌的相互作用,最终建立竞争优势。本文主要总结了T6SS的结构与组成,并重点对效应蛋白的装配以及其与免疫蛋白的作用机制的研究进展进行阐述,为以后靶向T6SS抗菌药物的研制提供新思路。 相似文献
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Rukui Zhu Yu Liang Huajian Luo Huishan Cao Yi Liu Shan Huang Qi Xiao 《Journal of molecular recognition : JMR》2023,36(1):e3000
In this work, binding interactions of artemisinin (ART) and dihydroartemisinin (DHA) with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated thoroughly to illustrate the conformational variation of serum albumin. Experimental results indicated that ART and DHA bound strongly with the site I of serum albumins via hydrogen bond (H-bond) and van der Waals force and subsequently statically quenched the intrinsic fluorescence of serum albumins through concentration-dependent manner. The quenching abilities of two drugs on the intrinsic fluorescence of HSA were much higher than the quenching abilities of two drugs on the intrinsic fluorescence of BSA. Both ART and DHA, especially DHA, caused the conformational variation of serum albumins and reduced the α-helix structure content of serum albumins. DHA with hydrophilic hydroxyl group bound with HSA more strongly, suggesting the important roles of the chemical polarity and the hydrophilicity during the binding interactions of two drugs with serum albumins. These results reveal the molecular understanding of binding interactions between ART derivatives and serum albumins, providing vital information for the future application of ART derivatives in biological and clinical areas. 相似文献
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The hemolymph of each noctuid species successfully parasitized by Chelonus near curvimaculatus possessed a parasitism-specific protein (PSP) previously identified in host T. ni (Insect Biochem. 19:445; 21:845). Expression of PSP occurred in a stage-specific manner in the stadium during which the host undergoes precocious metamorphosis. The appearance of the protein was not due to nutritional stress associated with parasitism of hosts, since starved nonparasitized larvae did not produce the protein, or to low juvenile hormone titers occurring in precociously metamorphosing hosts, but rather was dependent on the presence of the endoparasite larva. Results of in vivo incorporation experiments with [35S]-methionine showed that synthesis and subsequent appearance of the protein in the hemolymph of parasitized hosts was abrogated by prior surgical removal of endoparasite. Immunoprecipitation analysis of proteins from C. near curvimaculatus larvae cultured in vitro using antibodies specific to PSP indicated that the source of the protein was the endoparasite. Synthesis of PSP by the endoparasitic larvae with its subsequent secretion into the hemocoel of hosts was specific to the advanced stages of parasite development prior to its egression from the host. © 1993 Wiley-Liss, Inc. 相似文献
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Shiro Higashi Akinori Nakashima Hideki Ozaki Mikiko Abe Toshiki Uchiumi 《Journal of plant research》1993,106(1):47-54
The process of digestion of captured feeds in a pitcher, an insect-trapping organ, ofNepenthes was studied. Changes in bacterial population, pH and NH4
+ concentrations in pitcher juice were examined. Strong activities of both acid- and alkaline phosphatase, phosphoamidase,
esterase C4 and esterase C8 were found in the pitcher juice. Optimum pH of proteases in the juice and those secreted from
bacteria showed pH 3.0 and pH 8.0–9.0, respectively. Twenty six strains of bacteria were isolated from 4 pitchers: 10 strains
were gram positive, 16 strains were gram negative (10 strains had casein hydrolase activity). A proton excretion was induced
by NH4
+ released from the added solutions, and accordingly, the pH of the solutions fell. As a simulation model of the digestion
process of feeds in pitcher juice and polypeptone solution was added into the washed pitcher. A good correlation was found
among the NH4
+ concentration, pH and bacterial cell titer. 相似文献
89.
Brasilicardin A (BraA)是从致病性放线菌巴西诺卡菌(Nocardia brasiliensis) IFM 0406中发现的具有显著免疫抑制作用(IC50=0.057μg/mL)的二萜糖苷类化合物。BraA发挥免疫抑制活性的作用机制与现有临床常用的免疫抑制剂不同,BraA通过抑制氨基酸转运体L系统的转运进而影响T-淋巴细胞对氨基酸的摄入而发挥免疫抑制作用。相比目前已知的免疫抑制剂环孢菌素A、子囊霉素和他克莫司等,BraA在小鼠混合淋巴细胞反应中显示低毒、高效的优势。因此,BraA作为新型的免疫抑制剂,极具开发潜力,已成为全球免疫抑制剂发现新领域。但其结构复杂、合成困难,原菌种产率低且具有致病性,BraA及其类似物的获得已成为此类新型免疫抑制剂研究的瓶颈。本文综述了BraA的分子特征、药理活性、作用机制、目前获得的BraA类似物和衍生化方面的研究进展,以期为BraA及其类似物的高效生产提供参考。 相似文献
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