BACKGROUNDNicotinamide cofactor‐dependent oxidoreductases have been widely applied to the bioproduction of varieties of useful compounds. Efficient cofactor regeneration is often required for these oxidoreductase‐catalyzed reactions. Herein, enzymatic production of 1, 3‐dihydroxyacetone (DHA) via immobilized enzymes with in situ cofactor regeneration was reported.RESULTSGlycerol dehydrogenase (GDH) and NADH oxidase (Nox) were immobilized on two carriers: macroporous resin and epoxy functionalized magnetic nanoparticles (EFMN). Higher enzyme loading capacity and activity recovery were achieved on EFMN. A high immobilization yield of 90% and >70% recovery activity were obtained for both enzymes using EFMN as carriers. Besides, both immobilized enzymes showed enhanced pH stability and temperature tolerance. Co‐immobilized and mixed immobilized enzymes were evaluated for synthesis of DHA, and mixed immobilized enzymes showed higher catalytic rate. The mixed reaction system also was investigated in view of various operational factors. Under the optimal conditions, a high DHA concentration with mixed immobilized enzymes system can reach up to 3.5 mmol L–1, which was about four times higher than that without cofactor regeneration system.CONCLUSIONThe immobilized GDH and Nox on magnetic nanoparticles showed enhanced stabilities. A cofactor regeneration system with immobilized enzymes could be utilized for efficient production of DHA from inexpensive substrates. © 2018 Society of Chemical Industry

No abstract

Enzymatic preparation of low-molecular-weight chondroitin sulfate (LMWCS) has received increasing attention. In this work, a chondroitin sulfate lyase ABC (Chon-ABC) was successfully cloned, expressed, and characterized. The Km and Vmax of the Chon-ABC were 0.54 mM and 541.3 U mg−1, respectively. The maximal activity was assayed as 500.4 U mg−1 at 37 °C in pH 8.0 phosphate buffer saline. The half-lives of the Chon-ABC were 133 d and 127 min at 4 °C and 37 °C, respectively. Enzymatic preparation of LMWCS was performed at room temperature for 30 min. The changes between the substrate and product were analyzed with mass spectrometry (MS), high-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR). Overall, the Chon-ABC from Bacteroides thetaiotaomicron is competitive in large-scale enzymatic preparation of LMWCS for its high activity, stability, and substrate specificity.