双糖基化人溶菌酶中N-乙酰乳糖胺重复序列的糖基化位点选择性合成。
Glycosylation-site-selective synthesis of N-acetyl-lactosamine repeats in bis-glycosylated human lysozyme.
作者信息
Melcher R, Hillebrand A, Bahr U, Schröder B, Karas M, Hasilik A
机构信息
Institut für Physiologische Chemie, Philipps-Universität Marburg, D-35033 Marburg, Germany.
出版信息
Biochem J. 2000 Jun 15;348 Pt 3(Pt 3):507-15.
We have studied the elongation of oligosaccharides containing N-acetyl-lactosamine repeats using glycosylated human lysozyme mutants as a model. We reported previously that a combination of glycosylation sites at the 49th (site IV) and 68th (site II) amino acid residues of the protein particularly stimulates the synthesis of N-acetyl-lactosamine repeats [Melcher, Grosch, Grosse and Hasilik (1998) Glycoconjugate J. 15, 987-993]. In the present study we show that it is the carbohydrate attached to site IV that is selectively affected. It contains more N-acetyl-lactosamine repeats when site II is glycosylated in the same molecule. As a corollary of the glycosylation at site II, the synthesis of a third antenna at site IV is increased. The triantennary oligosaccharides at site IV contain more N-acetyl-lactosamine repeats than the biantennary ones. Thus placing a carbohydrate at site II stimulates the branching and the elongation of the carbohydrate at the other site.
我们以糖基化人溶菌酶突变体为模型，研究了含有N-乙酰乳糖胺重复序列的寡糖的延伸情况。我们之前报道过，蛋白质第49位（位点IV）和第68位（位点II）氨基酸残基处糖基化位点的组合特别能刺激N-乙酰乳糖胺重复序列的合成[梅尔彻、格罗施、格罗斯和哈西利克（1998年）《糖缀合物杂志》15卷，987 - 993页]。在本研究中，我们表明，选择性受影响的是连接在位点IV上的碳水化合物。当同一分子中的位点II发生糖基化时，它含有更多的N-乙酰乳糖胺重复序列。作为位点II糖基化的一个必然结果，位点IV处第三天线的合成增加。位点IV处的三分支寡糖比双分支寡糖含有更多的N-乙酰乳糖胺重复序列。因此，在位点II处放置一个碳水化合物会刺激另一个位点处碳水化合物的分支和延伸。
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