α-Galactobiosyl units: thermodynamics and kinetics of their formation by transglycosylations catalysed by the GH36 α-galactosidase from Thermotoga maritima
作者:Anna S. Borisova、Dina R. Ivanen、Kirill S. Bobrov、Elena V. Eneyskaya、Georgy N. Rychkov、Mats Sandgren、Anna A. Kulminskaya、Michael L. Sinnott、Konstantin A. Shabalin
DOI:10.1016/j.carres.2014.11.003
日期:2015.1
a limiting factor for application of the enzyme in the directed synthesis of oligogalactosides. However, this property can be used as a convenient tool in studies of thermodynamics of a glycosidic bond. Here, a novel approach to energy difference estimation is suggested. Both transglycosylation and hydrolysis of three types of galactosidic linkages were investigated using total kinetics of formation
来自滨海嗜热菌(TmGal36A)的α-半乳糖苷酶的广泛区域选择性是该酶在寡半乳糖苷的定向合成中应用的限制因素。但是,该性质可以用作研究糖苷键热力学的方便工具。在此,提出了一种新的能量差估计方法。使用由海藻T.36(一种保留性的外泌作用糖苷水解酶)的单体糖苷水解酶家族36α-半乳糖苷酶催化的pNP-半乳糖苷的形成和水解的总动力学,研究了三种类型的半乳糖苷键的转糖基化和水解。我们估计了1,2-和1,3-键之间的过渡态自由能差(DeltaDeltaG(double dagger)0值等于5.34 +/- 0.85 kJ / mol)和1,6-键和1,之间 在由TmGal36A催化的反应过程中,pNP-半乳糖苷中有3个键(DeltaDeltaG(双匕首)0 = 1.46 +/- 0.23 kJ / mol)。利用自由能差形成和水解糖苷键(DeltaDeltaG(双匕首)F-DeltaDeltaG(双匕首)H),我们发现1