EFFECTS OF GLUTAMINES ON THE SELF-ASSEMBLY OF A BETA-HAIRPIN FIBRILS

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。淀粉样蛋白原纤维是错误折叠蛋白的结构良好的聚集体，与许多流行的人类疾病，如阿尔茨海默氏痴呆症和克雅氏病有关。淀粉样蛋白原纤维由多种蛋白质和合成肽组成，包括许多富含谷氨酰胺的序列，但淀粉样蛋白原纤维具有共同的交叉-结构。即使有这种常见的排列和富含谷氨酰胺的淀粉样蛋白的原子结构的多种模型，控制淀粉样蛋白形成和稳定的主要力量还没有被实验确定。由于先前研究的力不包括侧链氢键，我们通过从头设计创建了一个富含谷氨酰胺的模型系统，能够进行这些相互作用。该模型以二硫化物环化形式形成β -片结构，如圆二色性所示，并表现出原纤维形态，如原子力显微镜所示。ATR-FTIR光谱通过监测聚合效应产生的尖锐振动带的存在来确定这些肽的聚合程度。通过多种赖氨酸残基的掺入，希望通过盐和pH的变化来控制参与纤维形成的折叠和聚合动力学，并将有助于研究该过程的早期中间体。未来的研究使用这种新模型系统的变化将允许确定谷氨酰胺侧链氢键在原纤维生长和稳定性中的重要性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Amyloid fibrils, well-structured aggregates of misfolded protein, have been implicated in a number of prevalent human diseases such as Alzheimer's dementia and Creutzfeldt-Jacob's disease. While formed by a diverse repertoire of proteins and synthetic peptides, including many with glutamine-rich sequences, amyloid fibrils have a common cross-beta-structure. Even with this common arrangement and multiple models for the atomic structure of glutamine-rich amyloid, a dominant set of forces governing amyloid formation and stabilization have not been experimentally determined. Since the forces previously investigated have not included side-chain hydrogen bonding, we created a glutamine-rich model system by de novo design that is capable of these interactions. This model, in a disulfide-cyclized form, forms beta-sheet structures, as shown by circular dichroism, and exhibits a fibril morphology, as shown by atomic force microscopy. ATR-FTIR spectroscopy was used to determine the degree of polymerization of these peptides by monitoring the presence of a sharp vibrational band resulting from aggregation effects. Through the incorporation of multiple lysine residues, it is hoped that the kinetics of folding and polymerization involved in fibril formation can be controlled via changes in salt and pH and will facilitate the study of the early intermediates of this process. Future investigation using variations on this new model system will allow the determination of the importance of glutamine side-chain hydrogen bonding in fibril growth and stability.