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装饰着 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 仍然是有限的。越来越多的证据正在确立糖基化作为蛋白质决定因素的核心作用 折叠、排序、处理、导出和功能。推进这一理解需要平台来 系统地研究糖基化改变引起的蛋白质形态和功能的变化，这有 历史上需要在蛋白质生产和碳水化合物合成方面具有高度专业化的专业知识。作为一个实用的 作为替代方案，我的研究项目开发了碳水化合物修饰的多肽，这些多肽可以自组装成纤维 作为糖基化蛋白质的合成类似物的结构。拟议的研究计划将研究如何 糖基化作为蛋白质折叠的替代物会影响多肽的纤维化，并将利用这些见解来 使新生物材料的设计成为可能。支持这项研究的初步数据表明， 糖基化可以促进合成的b-折叠纤化多肽分级自组装成各向异性 排列的纳米纤维网络。这些各向异性网络还抵制非特定的生物相互作用。 由于组装的碳水化合物的紧急功能，选择性地识别碳水化合物结合蛋白 变成了一个多价位的架构。这项拟议研究的主要假设是糖基化 通过建立分子间作用力来影响多肽的纤化和纳米纤维的功能 在防止非特定关联的同时进行绑定交互。为了测试这一点，我们将首先开发一种方法来 大范围碳水化合物修饰的纤毛肽文库的可扩展、经济高效的合成 化学药学。然后，我们将利用这个文库来研究糖基化对多肽动力学的影响 利用各种生物物理方法对所得纳米纤维的纤化和平衡形态进行了研究。一起， 这些研究将建立对糖基化作为多肽结构决定因素的基本理解 流光化。最后，我们将评估糖基化多肽纳米纤维作为生物材料的重要性。 以及润滑素的作用，这是一种软骨糖蛋白，在关节表面提供边界润滑，这是 在骨性关节炎进展过程中丢失。虽然我们使用人工合成的发光肽作为模型系统，但一般 通过这一研究计划所做的观察可望应用于自然界的生物物理学。 刺激多肽，也可能有助于理解粘蛋白和其他糖基化蛋白。 这项研究的成功将推动超分子生物材料领域的发展，因为它将碳水化合物建立为 一类新的控制多肽纤化的分子基序。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 通过创造用自然界中发现的各种碳水化合物化学修饰的多肽来应用。

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.