Molecular Modification of Ribitol Dehydrogenase and Efficient Catalysis of D-Psicose to Allitol

Allitol has wide applications in fields such as food and pharmaceuticals. To address the limited industrial production of allitol caused by the low catalytic efficiency of native ribitol dehydrogenase (RDH), we developed an efficient biotransformation method from D-psicose to allitol based on a computational design strategy. First, based on virtual saturation mutagenesis and disulfide bond prediction, combined with enzymatic property analysis, we screened for the highly stable combinatorial mutation variant S232P-S13C/G38C, which exhibited a 24.8% increase in the catalytic yield compared to the wild type. Formate dehydrogenase (FDH) was further introduced to construct a NADH regeneration system, which saved 90% of NADH consumption. Finally, through the optimization of enzymatic conversion conditions, the efficient synthesis of allitol was achieved, with a conversion rate of 94.3%. This study provides important theoretical and technical support for the industrial green production of allitol and related rare sugars.