Elucidating the Molecular Basis of the Carbohydrate-Carbohydrate Interaction

我们在这个项目中的目标是研究，并以这种方式更全面地了解碳水化合物与其他碳水化合物单位相互作用的方式。虽然我们对蛋白质-蛋白质和蛋白质-碳水化合物相互作用有很多了解，但我们对相应的碳水化合物-碳水化合物相互作用（CCI）缺乏详细的了解。然而，这些在广泛的生物学背景下是重要的，例如受精，细胞-细胞识别和细胞粘附。与CCI研究相关的一个主要问题是，它们本质上是薄弱的。出于这个原因，迄今为止的大多数工作都是在多价系统中完成的，其中许多基于碳水化合物的弱结合体协同作用，提供总体强相互作用（亲和力）。最好的类比是维可牢尼龙搭扣，其中许多小钩几乎没有单独的力量，共同作用以提供巨大的组合粘着力。然而，多价环境必然是宏观的，很难探究所涉及的具体相互作用的细节;为了保留魔术贴的类比，钩子是如何排列的，钩子的哪些特征是重要的，哪些不是？例如，我们知道碳水化合物结构的微小变化确实会导致CCI的变化（增加或减少）。然而，碳水化合物组分中的化学/结构变化如何转化为结合亲和力的细节尚不清楚。我们解决这个问题的策略是新的，基于将碳水化合物单元束缚（约束）到肽支架上，这将鼓励它们彼此相互作用。作为我们的主要检测方法，我们设计了灵敏的系统，该系统应响应并反过来使我们能够检测CCI。我们还有其他更严格的系统，这将允许我们定位碳水化合物并将它们彼此呈现，即迫使它们相互作用。然后，我们将使用一系列光谱方法来研究任何相互作用的性质，目的是阐明所涉及的相互作用的更多分子细节。这将导致更好地理解与CCI相关的机制，这在一系列生物环境中具有根本的重要性。因此，深入了解这些过程是如何工作的（通过在分子水平上理解它们），可能会导致我们能够预测和设计CCI的方法，即增强或抑制它们，并打开或关闭它们。反过来，这种理解以及识别和研究新的CCI的能力可以用于探测，从而更好地理解给定的生物学过程。因此，从本质上讲，这项工作的长期目标是促进我们对CCIs的基本理解，这对我们了解自然如何使用这一薄弱但重要的过程具有影响，为了实现这一目标，我们提出了一种新的方法来应对这一领域提出的挑战。

Our goal in this project is to study, and in this way understand more fully, the ways in which a carbohydrate interacts with other carbohydrate units. While much is known of protein-protein and protein-carbohydrate interactions, we lack a detailed understanding of the corresponding carbohydrate-carbohydrate interactions (CCIs). These are, nevertheless, important in a wide range of biological contexts, e.g. fertilisation, cell-cell recognition and cell adhesion. A major issue associated with the study of CCIs is that they are inherently weak. For this reason, most work to date has been done within multivalent systems where many weak carbohydrate-based associations act cooperatively to provide an overall strong interaction (avidity). The best analogy for this is Velcro, where many little hooks with little individual strength, act together to provide immense combined sticking power. However, multivalent environments are necessarily macroscopic, and it is hard to probe the detail of the specific interactions involved; to retain the Velcro analogy, how do the hooks line up and which features of the hooks are important and which are not? For instance, we know that small changes in carbohydrate structure do lead to changes (either a gain or loss) of CCIs. However, the details how chemical/structural changes in the carbohydrate components translate to binding affinities is not understood. Our strategy to tackle this problem is new and is based on tethering (constraining) carbohydrate units on to a peptide scaffold which will encourage them to interact with one another. As our primary assay, we have designed sensitive systems that should respond to and, in turn, allow us to detect CCI's. We have other systems, which are more rigid, that will then allow us to localise carbohydrates and present them to one another, i.e. force them to interact. We will then use a range of spectroscopic methods to study the nature of any interaction with the aim of elucidating more of the molecular detail of the interactions involved. This will then lead to a better understanding of the mechanisms associated with CCIs, which are of fundamental importance in a range of biological environments. Insight into how these processes work (by understanding them at the molecular level), therefore, may then lead to approaches that could allow us to predict and engineer CCIs i.e. enhance or inhibit them, and turn them on or off. In turn, this understanding and the ability to identify and study new CCIs could be used to probe and thereby gain a better understanding of a given biology process. Thus, in essence, the long-term aim of this work is to contribute to our fundamental understanding of CCIs, which has implications for our knowledge of how nature uses this weak but important process, and to achieve this we propose a new approach to tackle the challenges that this field presents.