Food Process Engineering Group, Wageningen University, Bomenweg 2, 6703 HD, Wageningen, The Netherlands.
J Agric Food Chem. 2013 Jul 3;61(26):6458-64. doi: 10.1021/jf4008554. Epub 2013 Jun 24.
The effects of high concentrations of carbohydrates on the o-nitrophenyl β-d-galactopyranoside (oNPG) converting activity of β-galactosidase from Bacillus circulans are studied to get a better understanding of the enzyme behavior in concentrated and complicated systems in which enzymatic synthesis of galacto-oligosaccharides is usually performed. The components that were tested were glucose, galactose, lactose, sucrose, trehalose, raffinose, Vivinal GOS, dextran-6000, dextran-70,000, and sarcosine. Small carbohydrates act as acceptors in the reaction. This speeds up the limiting step, which is binding of the galactose residue with the acceptor and release of the product. Simultaneously, both inert and reacting additives seem to cause some molecular crowding, which results in a higher enzyme affinity for the substrate. The effect of molecular crowding on the enzyme activity is small compared to the effect of carbohydrates acting in the reactions as acceptors. The effects of reactants on β-galactosidases from B. circulans, A. oryzae, and K. lactis are compared.
研究了高浓度碳水化合物对环状芽孢杆菌β-半乳糖苷酶转化邻硝基苯-β-d-半乳糖苷（oNPG）活性的影响，以便更好地了解在浓缩和复杂的体系中酶的行为，这些体系通常用于酶法合成半乳糖低聚糖。测试的成分有葡萄糖、半乳糖、乳糖、蔗糖、海藻糖、棉子糖、Vivinal GOS、葡聚糖 6000、葡聚糖 70000 和肌氨酸。小分子碳水化合物在反应中作为受体。这加快了限速步骤，即与受体结合的半乳糖残基和产物的释放。同时，惰性和反应性添加剂似乎都会导致一些分子拥挤，从而使酶对底物具有更高的亲和力。与作为受体的碳水化合物在反应中起作用相比，分子拥挤对酶活性的影响较小。比较了反应物对环状芽孢杆菌、米曲霉和乳球菌β-半乳糖苷酶的影响。
