Scudder P, Doom J P, Chuenkova M, Manger I D, Pereira M E
Division of Protein Biochemistry, Monsanto Co., St. Louis, Missouri 63167.
J Biol Chem. 1993 May 5;268(13):9886-91.
The substrate specificity, physico-chemical, and kinetic properties of the trans-sialidase from Trypanosoma cruzi have been investigated. The enzyme demonstrates activity towards a wide range of saccharide, glycolipid, and glycoprotein acceptors which terminate with a beta-linked galactose residue, and synthesizes exclusively an alpha 2-3 sialosidic linkage. Oligosaccharides which terminate in Gal beta 1-4(Fuc alpha 1-3)GlcNAc, Gal beta 1-3(Fuc alpha 1-4)GlcNAc, or Gal alpha 1- are not acceptor-substrates. The enzyme utilizes alpha 2,3-linked sialic acid when the donor species is an oligosaccharide and can also transfer, at a low rate, sialic acid from synthetic alpha-sialosides such as p-nitrophenyl-alpha-N-acetylneuraminic acid, but NeuAc alpha 2-3Gal beta 1-4(Fuc alpha 1-3)Glc is not a donor-substrate. The trans-sialidase has an apparent pH optimum of 7.9 and a temperature optimum of 13 degrees C. The kinetic properties of the enzyme suggest that the trans-sialylation reaction may occur via a rapid equilibrium random or steady-state ordered mechanism. A method for immobilizing the enzyme is described together with examples of its use for the synthesis of oligosaccharide and glycoprotein precursors of sialyl-Lewis and sialyl-Lewis.
已经对克氏锥虫转唾液酸酶的底物特异性、物理化学性质和动力学性质进行了研究。该酶对多种以β-连接的半乳糖残基结尾的糖类、糖脂和糖蛋白受体具有活性，并仅合成α2-3唾液酸苷键。以Galβ1-4（Fucα1-3）GlcNAc、Galβ1-3（Fucα1-4）GlcNAc或Galα1结尾的寡糖不是受体底物。当供体为寡糖时，该酶利用α2,3-连接的唾液酸，并且还能以低速率从合成的α-唾液酸苷如对硝基苯基-α-N-乙酰神经氨酸转移唾液酸，但NeuAcα2-3Galβ1-4（Fucα1-3）Glc不是供体底物。转唾液酸酶的表观最适pH为7.9，最适温度为13℃。该酶的动力学性质表明转唾液酸化反应可能通过快速平衡随机或稳态有序机制发生。描述了一种固定该酶的方法以及其用于合成唾液酸化路易斯和唾液酸化路易斯寡糖和糖蛋白前体的实例。
