Improvement in thermal stability of l-fucose dehydrogenase by chemical modification and additives for use as an NADPH recycling reagent

Chemical modification and addition of stabilizers were evaluated to stabilize l-fucose dehydrogenase (FDH) in mild alkaline which is required for NADPH recycling used in a glutamate dehydrogenase (GDH)-catalyzed elimination of ammonia. FDH lost all its activity at pH 9 after 10 min at 50 °C, while FDH conjugated with dextran retained about 30% activity. EDTA or citric acid, at 50–100 mM, increased the thermal stability of FDH with retention of more than 70–80% activity after heat-treatment. FDH was then functional for NADPH regeneration.