Liu Y L, Hoops G C, Coward J K
Department of Chemistry, College of Pharmacy, University of Michigan, Ann Arbor 48109-1055, USA.
Bioorg Med Chem. 1994 Nov;2(11):1133-41. doi: 10.1016/s0968-0896(00)82065-9.
A chemoenzymatic synthesis of homogeneous neoglycoproteins and glycopeptides was explored using oligosaccharyltransferase isolated from yeast. Neither the microsomal form nor the solubilized form of the enzyme catalyzed the transfer of the core Glc3Man9(GlcNAc)2 oligosaccharide to chemically modified ribonuclease A or alpha-lactalbumin. Similarly, no transfer was observed to the 32-amino acid peptide hormone, calcitonin, by either the membrane-bound or soluble form of oligosaccharyltransferase. However, a 17-amino acid fragment of yeast invertase with the unusual sequence containing two overlapping glycosylation sequons proved to be a good substrate, slightly less effective than the well studied tripeptide, Bz-Asn-Leu-Thr-NH2. Product analysis using gel permeation chromatography showed that the expected glycopeptides were formed and endo H-catalyzed cleavage of the oligosaccharide portion from the glycopeptides demonstrated that the glycopeptides contained the same carbohydrate moiety.
利用从酵母中分离出的寡糖基转移酶探索了均一化新糖蛋白和糖肽的化学酶法合成。该酶的微粒体形式和可溶形式均未催化核心Glc3Man9(GlcNAc)2寡糖转移至化学修饰的核糖核酸酶A或α-乳白蛋白。同样，寡糖基转移酶的膜结合形式或可溶形式均未观察到其将寡糖转移至32个氨基酸的肽激素降钙素上。然而，酵母转化酶的一个17个氨基酸的片段，其具有包含两个重叠糖基化序列的异常序列，被证明是一个良好的底物，其效果略逊于经过充分研究的三肽Bz-Asn-Leu-Thr-NH2。使用凝胶渗透色谱法进行的产物分析表明，形成了预期的糖肽，并且糖肽中寡糖部分的内切糖苷酶H催化裂解表明糖肽含有相同的碳水化合物部分。
