Lu P P, Hindsgaul O, Compston C A, Palcic M M
Department of Chemistry, University of Alberta, Edmonton, Canada.
Bioorg Med Chem. 1996 Nov;4(11):2011-22. doi: 10.1016/s0968-0896(96)00180-0.
The trisaccharide octyl 2-acetamido-2-deoxy-beta-D-glucopyranosyl -(1-->2)-alpha-D-mannopyranosyl-(1-->6)-beta-D-glucopyranoside (5) is an acceptor substrate for N-acetylglucosaminyltransferase-V (EC 2.4.1.155) which adds a beta-GlcNAc residue to OH-6 of the central Man-residue. In the present work, 10 analogues of 5, each missing the potentially reactive OH-6 group, were chemically synthesized. The key intermediate used was octyl 2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1-->2)-6-amino-6-deoxy-4-O -methyl-alpha-D-mannopyranosyl-(1-->6)-beta-D-glucopyranoside (6a), which was synthesized in stepwise fashion by sequential coupling of protected monosaccharide residues. The 6'-amino group in 6a, was then selectively derivatized by either acylation or alkylation with hydrophobic, hydrophilic, charged, aromatic and potential covalently inactivating groups. The 10 trisaccharide analogues thus produced were evaluated for inhibition against GlcNAcT-V isolated from hamster kidney. All of the compounds were competitive inhibitors with Ki values ranging from 21 to 297 microM. These results indicate that acceptor substrate (or inhibitor)-enzyme complex does not involve critical recognition contacts at the position of transfer.
三糖辛基2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基-(1→2)-α-D-吡喃甘露糖基-(1→6)-β-D-吡喃葡萄糖苷(5)是N-乙酰葡糖胺基转移酶-V(EC 2.4.1.155)的受体底物，该酶将一个β-GlcNAc残基添加到中心甘露糖残基的OH-6位。在本研究中，化学合成了5的10种类似物，每种类似物都缺少潜在的反应性OH-6基团。所使用的关键中间体是辛基2-乙酰氨基-2-脱氧-β-D-吡喃葡萄糖基-(1→2)-6-氨基-6-脱氧-4-O-甲基-α-D-吡喃甘露糖基-(1→6)-β-D-吡喃葡萄糖苷(6a)，它是通过受保护的单糖残基的顺序偶联以逐步方式合成的。然后，6a中的6'-氨基通过用疏水、亲水、带电荷、芳香和潜在的共价失活基团进行酰化或烷基化而被选择性衍生化。对由此产生的10种三糖类似物进行了针对从仓鼠肾中分离的GlcNAcT-V的抑制作用评估。所有化合物均为竞争性抑制剂，Ki值范围为21至297μM。这些结果表明受体底物(或抑制剂)-酶复合物在转移位置不涉及关键的识别接触。
