SYSTEMATIC STUDY OF THREE TYPES OF GLYCOSYLTRANSFERASES

细胞黏附蛋白的天然粘蛋白配体(L) P-选择素)和各种与肿瘤相关的核心2，0连接的糖蛋白 已知含有Galb1->4GlcNAcb1-6(Galb1-3)GalNAca->结构。相对的 人们对其精确的底物特性知之甚少。 糖基转移酶可以改变这一部分。这项提案的核心是 作用于两个半乳糖残基的糖基转移酶的研究 (Galb1-4和Galb1-3)。我们的首要利益是 研究2，3-唾液酸基转移酶。我们还包括了对两个 1，2-岩藻糖基转移酶和1，4GlcNAc-转移酶。一个独特而又共同的 这些酶的特点是它们更喜欢这种核心2，分支的 它们在简单Galbl-4GlcNAcb和Galbl上的活性结构 3GalNAca二糖。我们计划采购一系列Core2分支 作为糖蛋白的一部分出现的结构和其他结构 糖脂用于研究这些酶的特异性。我们将研究 不同α-2，3-唾液酸基转移酶和ST3GalI-IV的特异性。 计划从选定的来源提纯这些酶并检查它们的 化合物光谱的专一性。我们研究这些问题的基本原理 酶的作用的综合知识将使我们能够 阐明生物合成途径；例如，Fuca1 在0链接中找到的-2Galbl-&gt；GlcNAcbl-6(NeuAca2-3Galb1-3)GalNAca1-， 糖蛋白。我们还假设，这些酶的综合知识 从给定的肿瘤组织或细胞系来源获取的数据将为我们提供有关 低聚糖部分的结构，它可以作为 肿瘤相关抗原。因此，作为一项长期目标，拟议的 生化研究可以为未来的使用带来新的碳水化合物表位。 这个程序还允许我们为化学合成设计新的方法 我们的目标结构。核磁共振研究在确定核磁共振中起重要作用 我们合成化合物的结构。这一计划一直是 支持我们的综合努力，重点是实现以下目标 目的：a)获得对专属性研究有重要意义的化合物。 B)合成特定的修饰受体，该受体可用于单个 酶活性。C)获得高度特异的配体，用于纯化我们的 选定的糖基转移酶。D)专业性研究将为我们提供 为设计修饰类似物作为这些药物的抑制剂提供有价值的信息 酵素。作为一个长期目标，这两种抑制剂的组合 产生人类肿瘤相关抗原和抗原的关键酶 疫苗可能被证明对癌症的治疗有益。

The natural mucin ligands for cell adhesion proteins (L- & P-selectin) and various tumor-associated core 2, 0-linked glycoproteins are known to contain the Galb1->4GlcNAcb1-6(Galb1-3)GalNAca-> structure. Relatively little is known of the precise substrate specificities of the glycosyltransferases that can modify this moiety. This proposal is centered on the study of selected glycosyltransferases which act on two galactose residues (Galb1-4 and Galb1-3) of this branched tetrasaccharide. Our prime interest is to study 2,3-sialyltransferases. We have also included the study of two a1,2-fucosyltransferases and a1,4GlcNAc-transferases. One unique and common characteristic of these enzymes is that they prefer this core 2, branched structure for their activities over the simple Galbl-4GlcNAcb and Galbl 3GalNAca disaccharides. We plan to procure a series of core 2 branched structures and other structures which occur as a part of glycoproteins and glycolipids for investigating the specificity of these enzymes. We will examine the specificity of different a2,3-sialyltransferases and ST3Gal I - IV. We also plan to purify these enzymes from selected sources and examine their specificity with a spectrum of compounds. Our rationale for the study of these enzymes is that the combined knowledge of their actions will enable us to elucidate the biosynthetic pathways of; e.g. Fuca1 -2Galbl->GlcNAcbl-6(NeuAca2-3Galb1-3)GalNAca1-, as found in 0-linked glycoproteins. We also hypothesize that the combined knowledge of these enzymes from a given tumor tissue or cell line source will provide us information on the structures of oligosaccharide moieties which can occur as part of tumor-associated antigens. Thus, as a long term objective, the proposed biochemical studies can lead to novel carbohydrate epitopes for future use. This program also allows us to design new approaches for the chemical synthesis of our target structures. NMR studies play an important role in determining the structure of our synthetic compounds. This program has been the prime source of support for our synthetic efforts which are focused to fulfill the following objectives: a) To obtain compounds that are important for specificity studies. b) To synthesize specific modified acceptors which can be used for a single enzyme activity. c) To acquire highly specific ligands for purification of our selected glycosyltransferases. d) Specificity studies will provide us with valuable information for designing modified analogs as inhibitors of these enzymes. As a long term objective, the combination of both inhibitors of critical enzyme for generating human tumor associated antigen and antigens as vaccine may prove beneficial in the treatment of cancer.