Chemoenzymatic Synthesis of Glycosaminoglycan Oligos

糖胺聚糖(GAG)是一类结构复杂、高度硫酸盐化、多分散、线性的糖胺多聚糖。 多糖类。肝素、硫酸肝素、硫酸软骨素、硫酸皮肤素和透明质酸 这个家庭的所有成员。肝素是研究最广泛的Gag，是丝氨酸蛋白酶的主要激活剂。 抑制剂以及最近的肝素和其他GAG已被证明在调节 细胞生长和细胞与细胞的相互作用。全世界每年生产近300吨肝素。 从动物组织中提取，用作抗凝血剂。肝素与抗凝血酶III结合，使其成为一种有效的 凝固性丝氨酸蛋白酶的抑制剂。与抗凝血酶III结合的五糖序列具有 经过60步化学合成，产率为0.25%。尽管有这样的挑战 合成，这种五糖目前被用于治疗。关于这一事件的报道很少 由其他GAG组成的寡糖的合成。GAG的化学酶促合成 寡糖是利用多糖裂解酶和合成酶提出的。这些种类的酶 首先在首席调查员和协查员的实验室中分离和鉴定。这个 这些人工合成的低聚糖与一些Gag结合蛋白的相互作用将被评估。 目前的提案有四个具体目标。这些具体目标包括：1.低聚糖将 在各种糖基化反应中使用多糖裂解酶作为底物进行评价 本发明的目的是合成氨基寡糖。2.合成酶将用于延伸GAG 使用标准UDP单糖供体和新型部分保护的寡糖受体 UDP单糖供体。3.RTIL将作为化学和酶反应的溶剂 多糖裂解酶制备的寡糖的糖基化。4.人工合成材料的相互作用 低聚糖将使用各种Gag结合蛋白进行评估。 GAG寡糖正在被合成以评估选择性， 与蛋白质结合伙伴的高亲和力相互作用。三维结构识别潜在的结合 但仅凭这些信息并不能确切地预测主要的约束力。只有合成 可以为生物学理解提供结构洞察力，从而导致新的治疗剂。

Glycosaminoglycans (GAGs) are a family of structurally complex, highly sulfated, polydisperse, linear polysaccharides. Heparin, heparan sulfate, chondroitin sulfates, dermatan sulfate, and hyaluronic acid are all members of this family. Heparin, the most widely studied GAG, is a major activator of serine protease inhibitors and more recently heparin and other GAGs have been shown to be important in the regulation of cell growth and cell-cell interaction. Nearly 300 metric tons of heparin are produced worldwide each year from animal tissue and used as an anticoagulant. Heparin binds to antithrombin III making it a potent inhibitor of coagulation serine proteases. The pentasaccharide sequence binding to antithrombin III, has been chemically synthesized in >60 synthetic steps and in < 0.25% yield. Despite this challenging synthesis, this pentasaccharide is currently being used therapeutically. There have been few reports of the synthesis of the oligosaccharide comprising of the other GAGs. The chemoenzymatic synthesis of GAG oligosaccharides is proposed using polysaccharide lyases and synthases. These classes of enzymes were first isolated and characterized in the laboratories of the principal investigator and co-investigator. The interaction of these synthetic oligosaccharides to a number of GAG-binding proteins will be evaluated. There are four specific aims in the current proposal. These specific aims include: 1 .Oligosaccharides will be prepared using polysaccharide lyases for evaluation as substrates in a variety of glycosylation reactions directed at the synthesis of GAG oligosaccharides. 2. Synthases will be used to extend GAG oligosaccharide acceptors using both standard UDP monosaccharide donors and novel, partially protected UDP monosaccharide donors. 3. RTILS will be used as solvents for the chemical and enzymatic glycosylation of polysaccharide lyase-prepared oligosaccharides. 4. The interaction of the synthesized oligosaccharides will be evaluated using a variety of GAG-binding proteins. GAG oligosaccharides are being synthesized to evaluate critical structural elements required for selective, high affinity interaction with protein binding partners. Three-dimensional structures identify potential bonding networks, but this information alone cannot predict definitively the major binding forces. Only the synthesis of analogs can afford the structural insights for biological understanding leading to new therapeutic agents.