A series of dansyl-labeled glycosides with di-, tetra-, and hexasaccharides carrying the terminal N-acetyllactosamine (LacNAc) sequence were synthesized as acceptor substrates for α2,6- and α2,3-sialyltransferases. As an alternative design, dansyl-labeled LacNAc glycoside carrying a long-spacer linked glycan was engineered by replacement of the LacNAc or lactose units with an alkyl chain. In addition, we designed a dansyl-labeled bi-antennary LacNAc glycoside as an N-linked oligosaccharide mimetic, such as asialo-α1-acid glycoprotein. The kinetic parameters for the transfer reaction of synthesized dansyl-labeled glycosides by sialyltransferases were determined by the fluorescent HPLC method. The catalytic efficiencies (V max/K m) of acceptor substrates carrying the terminal LacNAc sequence with various length glycans in the array for α2,6- and α2,3-sialyltransferases decreased in a glycan length-dependent manner. Furthermore, of the acceptor substrates tested, dansyl-labeled bi-antennary LacNAc glycoside displayed the most favorable K m value for α2,6- and α2,3-sialyltransferases.
一系列带有终端
N-乙酰
乳糖胺(LacNAc)序列的二糖、四糖和六糖的丹酰标记糖苷被合成为α2,6-和α2,3-
唾液酸转移酶的受体底物。作为替代设计,通过用烷基链替换LacNAc或
乳糖单元,开发了一种带有长间隔链接糖的丹酰标记LacNAc糖苷。此外,我们设计了一种丹酰标记的双
抗体LacNAc糖苷,作为N-linked
寡糖的模拟物,例如非
唾液酸α1-酸性糖蛋白。采用荧光HPLC方法确定了合成的丹酰标记糖苷在
唾液酸转移酶转移反应中的动力学参数。对于携带终端LacNAc序列的受体底物,其在不同长度糖链中的催化效率(V_max/K_m)呈现出依赖于糖链长度的下降趋势。此外,在测试的受体底物中,丹酰标记的双
抗体LacNAc糖苷对α2,6-和α2,3-
唾液酸转移酶显示出最有利的K_m值。