Glycosylation as a Structural Determinant in Peptide Fibrillization

项目摘要。所有的人类细胞表面和近一半的人类蛋白质都是由 碳水化合物（即，糖基化），但我们对糖基化在健康和疾病中的作用的理解 仍然有限。越来越多的证据表明，糖基化作为蛋白质的决定因素， 折叠、分拣、加工、出口等功能。推进这一理解需要平台 系统地研究糖基化改变引起的蛋白质形式和功能的变化， 历史上需要高度专业化的蛋白质生产和碳水化合物合成的专业知识。作为一个实际 或者，我的研究计划开发了碳水化合物修饰的肽，可以自组装成纤维 糖基化蛋白质的合成类似物。拟议的研究计划将研究如何 糖基化影响肽折叠作为蛋白质折叠的替代，并将使用这些见解， 设计新的生物材料。支持拟议研究的初步数据表明， 糖基化可以促进合成的B-折叠折叠肽分级自组装成各向异性的 排列的纳米纤维网络。这些各向异性网络抵抗非特异性生物相互作用， 选择性地识别碳水化合物结合蛋白，这是由于组装的碳水化合物的紧急功能 变成了多价结构。这项研究的首要假设是， 通过建立介导特异性的分子间力来影响肽的折叠和折叠功能 结合相互作用，同时防止非特异性关联。为了测试这一点，我们将首先开发一种方法， 用广泛的碳水化合物修饰的絮凝肽文库的可扩展的、成本有效的合成 化学然后我们将利用这个库来研究糖基化对肽动力学的影响 使用各种生物物理方法对所得纳米纤维进行纤维化和平衡形态学分析。在一起， 这些研究将建立对糖基化作为肽的结构决定因素的基本理解 固定化最后，我们将评估糖基化肽纳米纤维作为生物材料， 和润滑素的功能，一种软骨糖蛋白，在关节表面提供边界润滑， 骨关节炎进展期间丢失。虽然我们使用合成的凝血肽作为模型系统，但一般来说， 通过这项研究计划所作的观察，预计将适用于生物物理学的自然 此外，它还可能有助于理解粘蛋白和其他密集糖基化的蛋白质。 这项研究的成功将通过建立碳水化合物作为超分子生物材料， 一类新的控制肽折叠的分子基序。最终，这项研究将支持未来 努力开发具有生物医学所需的新结构和功能特性的生物材料， 通过产生用遍及自然界的各种碳水化合物化学修饰的肽来应用。

Project Summary. All human cell surfaces and nearly half of all human proteins are decorated with carbohydrates (i.e., glycosylated), yet our understanding of the role of glycosylation in health and disease remains limited. Increasing evidence is establishing a central role for glycosylation as a determinant of protein folding, sorting, processing, export, and function. Advancing this understanding requires platforms to systematically study changes in protein form and function resulting from altered glycosylation, which has historically required highly specialized expertise in protein production and carbohydrate synthesis. As a practical alternative, my research program develops carbohydrate-modified peptides that self-assemble into fibrillar architectures as synthetic analogs of glycosylated proteins. The proposed research program will study how glycosylation influences peptide fibrillization as a surrogate for protein folding, and will use these insights to enable design of new biomaterials. Preliminary data supporting the proposed research demonstrate that glycosylation can facilitate hierarchical self-assembly of a synthetic b-sheet fibrillizing peptide into anisotropic networks of aligned nanofibers. These anisotropic networks resist non-specific biological interactions yet selectively recognize carbohydrate-binding proteins due to the emergent function of carbohydrates assembled into a multivalent architecture. The overarching hypothesis of the proposed research is that glycosylation influences peptide fibrillization and nanofiber function by establishing intermolecular forces that mediate specific binding interactions while preventing non-specific associations. To test this, we will first develop a method for scalable, cost-effective synthesis of a library of fibrillizing peptides modified with a broad range of carbohydrate chemistries. Then we will use this library to study the influence of glycosylation on the kinetics of peptide fibrillization and equilibrium morphology of the resultant nanofibers using various biophysical methods. Together, these studies will establish fundamental understanding of glycosylation as a structural determinant in peptide fibrillization. Finally, we will evaluate glycosylated peptide nanofibers as biomaterials that recapitulate the form and function of lubricin, a cartilage glycoprotein that provides boundary lubrication at the joint surface, which is lost during osteoarthritis progression. Although we use synthetic fibrillizing peptides as a model system, general observations made through this research program are expected to be applicable to the biophysics of natural fibrillizing peptides, and may also inform understanding of mucins and other densely glycosylated proteins. Success of this research will advance the field of supramolecular biomaterials by establishing carbohydrates as a new class of molecular motif for controlling peptide fibrillization. Ultimately, this research will support future efforts to develop biomaterials with new structural and functional properties that are desirable for biomedical applications by creating peptides modified with diverse carbohydrate chemistries found throughout nature.