Characterization of Carboxylic Acid Reductase from Immobilized onto Seplite LX120.

A multi-domain oxidoreductase, carboxylic acid reductase (CAR), can catalyze the one-step reduction of carboxylic acid to aldehyde. This study aimed to immobilize bacterial CAR from a moderate thermophile (CAR). It was the first work reported on immobilizing bacterial CAR onto a polymeric support, Seplite LX120, via simple adsorption. Immobilization time and protein load were optimized for CAR immobilization. The immobilized CAR showed optimal activity at 60 °C and pH 9. It was stable over a wide range of temperatures (10 to 100 °C) and pHs (4-11), retaining more than 50% of its activity. The immobilized CAR also showed stability in polar solvents. The adsorption of CAR onto the support was confirmed by Scanning Electron Microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, and Brunauer-Emmett-Teller (BET) analysis. The immobilized CAR could be stored for up to 6 weeks at 4 °C and 3 weeks at 25 °C. Immobilized CAR showed great operational stability, as 59.68% of its activity was preserved after 10 assay cycles. The immobilized CAR could also convert approximately 2.6 mM of benzoic acid to benzaldehyde at 60 °C. The successfully immobilized CAR on Seplite LX120 exhibited improved properties that benefit green industrial processes.