Self-Assembled Hybrid Nanoflowers of Manganese Phosphate and L-Arabinose Isomerase: A Stable and Recyclable Nanobiocatalyst for Equilibrium Level Conversion of D-Galactose to D-Tagatose

摘要

We report on the synthesis and characterization of a novel hybrid nanoflower of manganese and L-arabinose isomerase and its application in synthesis of D-tagatose, a rare sugar of high commercial value. An open reading frame of 1425 base pairs from Lactobacillus sakai was used to synthesis recombinant L-arabinose isomerase of 474 amino acids in E. coli. A hierarchical flower-like spherical structure with several nanopetals was self-assembled by using purified recombinant L-arabinose isomerase as the organic component and manganese phosphate as the inorganic component. The hybrid nanoflower was characterized by scanning electron microscopy, high-resolution transmission electron microscopy, confocal laser scanning microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Circular dichroism documented no change in structural properties of L-arabinose isomerase assembled in the hybrid nanoflower. Kinetic parameters of Larabinose isomerase were improved in the hybrid nanoflower. L-Arabinose isomerase in the manganese hybrid nanoflower was found to convert D-galactose to D-tagatose with a conversion rate of similar to 0%, without an addition of manganese in the reaction mixture. The hybrid nanoflowers exhibited excellent reusability and reproducibility during reaction cycle analysis. Hence, the developed manganese hybrid nanoflowers of L-arabinose isomerase shows promise for commercial production of the rare sugar D-tagatose.