Chemical biology tools for studying carbohydrate processing enzymes

用糖修饰蛋白质被称为蛋白质糖基化，这是所有生命王国中细胞蛋白质的一种常见修饰。糖基化在多细胞真核生物中尤其丰富，在这些真核生物中，超过一半的蛋白质被连接在一起的糖修饰，形成了众所周知的葡聚糖。人类基因组中约300个基因致力于糖共轭化合物的调节，突显了这些物种所发挥的重要作用。负责构建糖共轭的酶是糖基转移酶，而那些分解它们的酶称为糖苷酶。这些酶的重要性在于它们在调节糖结合物的结构和丰度方面所起的作用，糖结合物被发现可以改变蛋白质的功能，调节分子间的相互作用，并改变蛋白质的稳定性。过去几年的惊人发现也表明，蛋白质糖基化直接调节信号和转录。最近，美国国家科学院和国家研究理事会将糖科学领域确定为一个有前途的新兴研究领域，值得大力投资。*确实，蛋白质糖基化领域的研究有些落后于其他更突出的生物分子类别，如磷酸化。有几个原因可以解释进展中的这种差异。提出的理由之一是，现有的化学工具库有限，可供更广泛的研究界用来研究相关的多糖结构以及处理这些物种的酶。为了解决这一差距，我们研究计划的一个主要重点是开发化学工具，这些工具将极大地促进对了解较少被认识和了解较少的真核蛋白质糖基化形式的研究。在这个提案中，我们概述了一个主要以碳水化合物化学和酶学为基础的研究计划，包括三个目标。我们将创建探针来监测糖苷酶和糖基转移酶，并创建这些酶的抑制剂。这些努力产生的分子将在细胞中得到验证，以识别那些在细胞中活跃的分子。由此产生的新化学工具将使该领域能够提高我们对调节这些糖链结构的酶如何在细胞内发挥作用的理解。因此，这里开发的工具应该有助于获取知识，帮助其他领域的研究人员开发新的诊断或治疗方法。**

The modification of proteins with sugars is known as protein glycosylation and is a common modification of cellular proteins in all kingdoms of life. Glycosylation is particularly abundant in multicellular eukaryotes, where over half of all proteins are thought to be modified by sugars linked together for form what are known as glycans. The dedication of approximately 300 genes within the human genome to the regulation of glycoconjugates highlights the important roles played by these species. The enzymes responsible for building of glycoconjugates are glycosyltransferases and those that break them down are known as glycosidases. The importance of these enzymes rests in the roles they play in regulating the structures and abundance of glycoconjugates, which have been found to alter protein function, mediate molecular interactions, and alter the stability of proteins. Striking findings in the past few years have also shown that protein glycosylation acts directly to regulate signaling and transcription. Recently, the National Academy of Sciences and National Research Council (USA) identified the area of glycoscience as a promising and emerging area of research that merits significant investment.***Indeed, the field of protein glycosylation lags somewhat behind the study of other, more prominent, classes of biomolecules such as phosphorylation. Several reasons to account for this difference in progress have been made. Among the rationales proposed is that there is a limited repertoire of chemical tools available that can be used by the wider research community to study relevant glycans structures as well as the enzymes that process these species. To address this gap, a major thrust of our research program is directed toward developing chemical tools that will greatly facilitate research into understanding less appreciated and poorly understood forms of eukaryotic protein glycosylation. In this proposal we outlined a principally carbohydrate chemistry and enzymology-based program of research comprising three aims. We will create probes to monitor glycosidase and glycosyltransferase and to create inhibitors of these enzymes. The molecules resulting from these efforts will be validated in cells to identify those which are active in cells. The resulting new chemical tools will enable the field to improve our understanding of how the enzymes that regulate these glycan structures function within cells. The tools developed here should therefore help access knowledge that could help researchers in other fields develop new diagnostics or therapeutics.**