Immobilization of L-arabinitol dehydrogenase on aldehyde-functionalized silicon oxide nanoparticles for L-xylulose production

l-Xylulose is a potential starting material for therapeutics. However, its translation into clinical practice has been hampered by its inherently low bioavailability. In addition, the high cost associated with the production of l-xylulose is a major factor hindering its rapid deployment beyond the laboratory. In the current study, l-arabinitol 4-dehydrogenase from Hypocrea jecorina (HjLAD), which catalyzes the conversion of l-arabinitol into l-xylulose, was immobilized onto various carriers, and the immobilized enzymes were characterized. HjLAD covalently immobilized onto silicon oxide nanoparticles showed the highest immobilization efficiency (94.7 %). This report presents a comparative characterization of free and immobilized HjLAD, including its thermostability and kinetic parameters. The thermostability of HjLAD immobilized on silicon oxide nanoparticles was more than 14.2-fold higher than free HjLAD; the t(1/2) of HjLAD at 25 A degrees C was enhanced from 190 min (free) to 45 h (immobilized). In addition, the immobilized HjLAD retained 94 % of its initial activity after 10 cycles. When the immobilized HjLAD was used to catalyze the biotransformation of l-arabinitol to l-xylulose, 66 % conversion and a productivity of 7.9 g A center dot h(-1) A center dot L-1 were achieved. The enhanced thermostability and reusability of HjLAD suggest that immobilization of HjLAD onto silicon oxide nanoparticles has the potential for use in the industrial production of rare sugars.