手性修饰的氧化石墨烯对多肽聚集的影响研究

发布时间：2018-03-12 10:52

本文选题：淀粉样变性　切入点：手性　出处：《武汉理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：蛋白质错误折叠形成淀粉样聚集体是许多神经退行性疾病的主要诱因。体内蛋白质的纤维化与分子表面尤其是生物膜表面有重要关联。研究生物膜表面的性质如何影响蛋白质的纤维化对理解神经退行性疾病的发病机理非常重要。手性作为生物膜表面的主要性质,其如何影响蛋白质纤维化目前仍不清楚。我们从仿生的角度出发,采用不同手性的半胱氨酸修饰的氧化石墨烯(R(S)-Cys-GO)作为模型来研究表面的手性对淀粉样肽(Aβ40)纤维化的影响。我们通过EDC/NHS缩合的方法,将不同手性的半胱氨酸分子接枝到羧基化的GO上,然后通过原子力显微镜、拉曼、X-射线光电子能谱、X-射线能量色散谱、紫外可见光谱等测试表征手段对修饰后的GO进行表征。我们采用ThT荧光标记法、原子力显微镜、石英质量微天平等方法研究了不同手性的半胱氨酸修饰的GO与Aβ40的相互作用。结果表明R-Cys-GO能够抑制Aβ40在表面的吸附、成核以及随后的增长过程,而S-Cys-GO却会促进这些过程。我们通过圆二色谱等方法测定了不同手性的半胱氨酸修饰的GO对Aβ40纤维化过程中构象转变的影响。结果表明,表面手性能够显著影响Aβ40纤维化过程中的α-螺旋构象到β-折叠构象的转变。为了研究表面手性差异性的起源,我们分别将GO表面的半胱氨酸分子的羧基或者巯基保护起来,研究这些不同手性的半胱氨酸衍生物修饰的GO对Aβ40纤维化的影响。结果表明,羧基的保护会减弱不同手性的GO衍生物在影响Aβ40纤维化中的差异性;而巯基被保护后,相应的GO衍生物对Aβ40纤维化的影响几乎没有差异。这表明这些基团参与了与Aβ40的相互作用。荧光滴定和核磁共振的结果表明手性分子与多肽之间的立体相互作用可能是这种手性差异性的起源。进一步实验表明,表面的存在能够将手性分子与多肽之间的相互作用的差异性体现出来。GO表面与手性分子之间的距离也会影响这种手性差异性的体现,只有两者之间的距离足够近时,表面才能参与到手性分子和多肽的相互作用中使这种手性差异性体现出来。这些结果揭示了生物膜表面的手性在蛋白质纤维化中的重要作用,为理解蛋白质的纤维化提供了新的启示。
[Abstract]:Protein misfolding into amyloid aggregate is the main cause of many neurodegenerative diseases. Protein fibrosis in vivo is closely related to molecular surface, especially biofilm surface. The properties of biofilm surface such as. What affects protein fibrosis is important in understanding the pathogenesis of neurodegenerative diseases. Chirality is the main property of the biofilm surface. How it affects protein fibrosis is unclear. We're looking at bionics. The effects of chirality on amyloid A 尾 40 (A 尾 40) fibrosis were studied by using different chiral cysteine modified graphene oxide Cys-GOA as a model. EDC/NHS condensation method was used to study the effect of chirality on amyloid A 尾 40 fibrosis. Different chiral cysteine molecules were grafted onto carboxylated go, and then Raman X-ray photoelectron spectroscopy (Raman X-ray photoelectron spectroscopy) was used to analyze the energy dispersive spectra of X-rays. UV-Vis spectroscopy was used to characterize the modified go. We used ThT fluorescence labeling method, atomic force microscope, atomic force microscope, The interaction between different chiral cysteine modified go and A 尾 40 was studied by quartz mass microbalance. The results showed that R-Cys-GO could inhibit the adsorption, nucleation and subsequent growth of A 尾 40 on the surface. However, S-Cys-GO promoted these processes. The effects of different chiral cysteine modified go on conformation transition during A 尾 40 fibrosis were determined by circular dichroism. Surface chirality can significantly affect the transformation of 伪 -helix conformation to 尾 -fold conformation in the process of A 尾 40 fibrosis. In order to study the origin of surface chiral difference, we protect the carboxyl or thiol groups of cysteine molecules on go surface, respectively. The effects of these chiral cysteine derivatives modified go on A 尾 40 fibrosis were studied. The results showed that the protection of carboxyl groups weakened the difference of different chiral go derivatives in affecting A 尾 40 fibrosis, but the sulfhydryl group was protected. The effect of the corresponding go derivatives on A 尾 40 fibrosis is almost no different. This indicates that these groups are involved in the interaction with A 尾 40. The results of fluorescence titration and nuclear magnetic resonance indicate the stereoscopic interaction between chiral molecules and peptides. May be the origin of this chiral difference. Further experiments show that, The existence of surface can reflect the difference of interaction between chiral molecules and peptides. The distance between go surface and chiral molecules will also affect the expression of chiral differences, only when the distance between them is close enough, Surface ability to participate in the interaction of chiral molecules and peptides makes this chiral difference manifest. These results reveal the important role of chirality on the surface of biofilm in protein fibrosis. It provides new inspiration for understanding protein fibrosis.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ127.11;O629.72

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