Rare sugar production by coupling of NADH oxidase and l-arabinitol dehydrogenase

摘要

An efficient biocatalytic cell-free system containing L -arabinitol dehydrogenase (LAD) for L -arabinitol oxidation and NADH oxidase (Nox) for cofactor regeneration was successfully constructed and used for L -rare sugar production. The recombinant LAD (HjLAD) from Hypocrea jecorina suffered from NADH inhibition. Applying Nox to the cell-free HjLAD system drove the thermodynamically unfavorable equilibrium from L -arabinitol to L -xylulose, along with the regeneration of the oxidized cofactor NAD ~(+) . Response surface methodology was used to optimize the conditions for L -xylulose production. The optimal conditions for biocatalytic production of L -xylulose were found to be 4.9 U mL ~(?1) HjLAD, 8.2 mM NAD ~(+) at pH 8.0, and 30.9 °C; a high conversion rate of 78.4% was achieved under these conditions. We demonstrate a cell-free enzyme coupling system enabling efficient cofactor recycling and providing high yields of L -xylulose. The results indicate that this coupling system provides a new biocatalytic method for L -rare sugar production.