Glucoheptonic acid derivative as a new transgalactosylation product

Abstract

Transgalactosylation is increasingly used for modification of selected compounds because it may introduce new bioactive properties or improve existing ones. This paper presents the application of transgalactosylation activity of Kluyveromyces lactis β-galactosidase (EC 3.2.1.23) for a new derivative of glucoheptonic acid synthesis. The study concerned the impact of following factors on the course of reaction: content and ratio of substrates, enzyme dose, pH of the solution and the presence of salts. In the most favourable conditions (without salt), the final product concentration reached 54.5 g/L, which corresponded to 10.9% of dry matter. Research has shown that higher initial dry matter content results in higher product content (as % dm). The addition of 0.5–0.75 M MgCl2 or 1 M NaCl led to significantly increased yield. In contrast, the presence of MnCl2 or the lowest enzyme dose seemed to slow down the synthesis process. Increasing the pH over the optimal value for hydrolytic activity of β-galactosidase caused inhibition of transgalactosylation reaction. The molar ratio of 1.9:1 (sodium glucoheptonate:lactose) was the best among tested options. The described method allowed to successfully obtain a new compound with satisfactory yield in comparison to other transgalactosylation products.