Design and synthesis of oligosaccharides that interfere with glycoprotein quality-control systems
Design and synthesis of oligosaccharides that interfere with glycoprotein quality-control systems
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DOI：
10.1002/cbic.200500143
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发表时间：
2005-12-01
期刊：
影响因子：
3.2
通讯作者：
Ito, Y
中科院分区：
文献类型：
--
作者：
Arai, MA;Matsuo, I;Ito, Y
钙粘蛋白(CNX)及其可溶同系物钙网蛋白(CRT)是一种凝集素样分子伴侣蛋白，能帮助新合成的糖蛋白在粗面内质网(ER)中正确折叠。为了研究糖蛋白质量控制的机制，我们合成了与该系统相关的结构定义的高甘露糖型寡糖。本文报道了非天然十一糖2和七糖16的合成，它们是内质网质量控制系统的潜在抑制剂。它们都具有CNX/CRT结合的关键四糖元件(GLC(1)Man(3))，而缺乏识别葡萄糖苷酶II所需的五羟甲基支链。用等温滴定比色法(ITC)评价了这些寡糖与CRT的结合能力。正如预期的那样，它们中的每一个都对CRT有显著的亲和力，此外，这些化合物还被证明对葡萄糖苷II的消化具有抵抗力。以苹果酸脱氢糖(MDH)为底物，测定其阻断CRT湿分子伴侣功能的活性。它们的抑制作用与它们与CRT结合的亲和力很好地相关，两者都严重依赖于末端葡萄糖(GLC)残基的存在。
Calnexin (CNX) and its soluable homologue calreticulin (CRT) are lectin-like molecular chaperones that help newly synthesized glycoproteins to fold correctly in the rough endoplasmic reticulum (ER). To investigate the mechanism of glycoprotein-quality control, we have synthesized structurally defined high mannose-type oligosaccharides related to this system. The paper describes the synthesis of the non-natural undecsaccharide 2 and heptasaccharide 16, designed as potential inhibitors of the ER quality-control system. Each possesses the key tetrasaccharide element (Glc(1)Man(3)) critical for the CNX/CRT binding, while lacking the pentamannosyl branch required for glucosidase II recognition. These oligosaccharides were evaluated for their ability to bind CRT by isothermal titration colorimetry (ITC). As expected, each of them had a significant affinity towards CRT In addition, these compounds were shown to be resistant to glucosidose II digestion. Their activities in blocking the chaperone function of CRT wet I e next measured by using malate dehydrogenose (MDH) as a substrate. Their inhibitory effects were shown to correlate well with their CRT-binding affinities, both being critically dependent upon the presence of the terminal glucose (Glc) residue.