BIOSYNTHESIS OF COMPLEX CARBOHYDRATES IN BRAIN

大脑中复杂碳水化合物的生物合成

• 批准号: 3413618
• 负责人: LENNART RODEN
• 金额: $ 18.62万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-04-01 至 1994-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3413618
• 关键词: antigens; brain metabolism; carbohydrate biosynthesis; chemical synthesis; chick embryo; chondroitin sulfate B; chondroitin sulfates; enzyme substrate; glucuronosyltransferase; glycopeptides; glycosyltransferase; heparan sulfate; natural killer cells; oligosaccharides; phosphorylation; proteoglycan; serine; sugar phosphates; xylose

The long-term objective of this project is to elucidate the enzymatic reactions by which xylose-linked proteoglycans are assembled. Progress in this area has been hampered by lack of substrates, and, to remedy this situation in part, we propose to prepare a number of compounds suitable for this purpose. The main focus will be on substrates for the enzymes involved in the formation of the carbohydrate-protein linkage region and the first repeating disaccharide unit of the xylose-linked proteoglycans. Substrates of two types will be prepared: (1) serine-linked oligosaccharides will be synthesized chemically and (2) macromolecular substrates which are more akin to the natural substrates will be prepared by combined enzymatic and chemical degradation of chondroitin sulfate proteoglycan. Compounds in the first category include two serine-linked pentasaccharides from the linkage regions of chondroitin sulfate/dermatan sulfate and heparin/heparan sulfate, respectively. The general structure of the two compounds is: HexNAc-(1-4)-beta-GlcUA-(1-3)-beta-gal-(1- 3)-beta-Gal-(1-4)-beta-Xyl-(1-3)-O-L-Serine, in which HexNAc is beta-GalNAc or alpha-Glc-NAc. Xylose-containing glycopeptides with alternating serine and glycine residues and two compounds with phosphorylated xylose will also be synthesized, i.e. Xyl(2-P)-Ser and Gal-Xyl(2-P)-Ser. Since the newly discovered HNK-1 antigen, first detected on human natural killer lymphocytes but also widely distributed in nervous tissue, is structurally related to the proteoglycans, some aspects of its biosynthesis will also be examined. Specifically, the HNK-1 epitope, glucuronic acid 3- sulfate, and the proteoglycan-related terminal disaccharide, beta- GlcUA(3-S)-(1-3)-Gal, will be synthesized chemically and will be used in studies of the biosynthesis of the antigen. The primary objective of this work is to determine whether the glucuronosyltransferase which catalyzes transfer to galactose during formation of the antigen is identical to the enzyme involved in the formation of the proteoglycan linkage region. Enzyme sources for the testing of all substrates will be embryonic chick brain and embryonic chick cartilage in view of the prominent occurrence of the HNK-1 antigen in nervous tissue and the well- established use of chick cartilage in studies of proteoglycan biosynthesis. The importance of this project for the study of human disease is apparent from the results of our recent collaboration with Kresse and Quentin of the Univ. of Munster, which demonstrate that a patient with a progeria-like syndrome is deficient in galactosyltransferase I. This finding is the first demonstration of a genetic defect in proteoglycan biosynthesis in humans.

该项目的长期目标是阐明 二糖连接蛋白聚糖的酶促反应是 组装。 由于缺乏，该领域的进展受到了阻碍 底物，以及部分纠正这种情况，我们建议 准备许多适合此目的的化合物。 主 重点将放在涉及的酶的底物上 碳水化合物 - 蛋​​白链接区域的形成和第一个 木糖连接蛋白聚糖的重复二糖单位。 将准备两种类型的底物：（1）丝氨酸连接 寡糖将通过化学合成，（2） 大分子底物更类似于天然 底物将通过合并的酶和化学 软骨素硫酸盐蛋白聚糖的降解。 化合物 第一类包括两个丝氨酸连接的五糖。 硫酸软骨素/皮肤硫酸盐的连锁区域和 肝素/硫酸肝素。 一般结构 这两种化合物是：hexnac-（1-4）-beta-glcua-（1-3）-beta-gal-（1- 3）-beta-gal-（1-4）-beta-xyl-（1-3）-o-l-serine，其中己酸是 beta-galnac或alpha-GLC-NAC。 含木糖的糖肽 交替的丝氨酸和甘氨酸残基以及两种化合物 磷酸化的木糖也将合成，即xyl（2-p）-Ser 和gal-xyl（2-p）-Ser。 由于新发现的HNK-1抗原， 首先在人类天然杀手型淋巴细胞上检测到 分布在神经组织中，在结构上与 蛋白聚糖，其生物合成的某些方面也将是 检查。 具体而言，HNK-1表位，葡萄糖酸3- 硫酸盐和蛋白聚糖相关的末端二糖，β- glcua（3-s） - （1-3） - gal将化学合成，将是 用于抗原的生物合成研究。 主要 这项工作的目的是确定是否 葡萄糖醛酸转移酶催化转移到半乳糖 在形成期间，抗原与所涉及的酶相同 在蛋白聚糖链接区域的形成中。 酶 测试所有底物的来源将是胚胎小鸡 鉴于突出的脑和胚胎小鸡软骨 HNK-1抗原在神经组织和井中发生 在蛋白聚糖的研究中建立了小鸡软骨的使用 生物合成。 该项目对于研究的重要性 从我们最近的结果来看，人类疾病是显而易见的 与大学的Kresse和Quentin合作。芒斯特 这表明患有类似早期综合征的患者是 缺乏半乳糖基转移酶I。这一点是第一个 蛋白聚糖生物合成中遗传缺陷的证明 人类。