As
phenylalanine dehydrogenase (PheDH) plays an important role in the synthesis of chiral
drug intermediates and detection of
phenylketonuria, it is significant to obtain a PheDH with specific and high activity. Here, a PheDH gene, pdh, encoding a novel BhPheDH with 61.0% similarity to the known PheDH from Microbacterium sp., was obtained. The BhPheDH showed optimal activity at 60 °C and pH 7.0, and it showed better stability in hot environment (40-70 °C) than the PheDH from Nocardia sp. And its activity and thermostability could be significantly increased by
sodium salt. After incubation for 2 h in 3 M NaCl at 60 °C, the residual activity of the BhPheDH was found to be 1.8-fold higher than that of the control group (without NaCl). The BhPheDH could tolerate high concentration of
ammonium chloride and its activity could be also enhanced by the high concentration of
ammonium salts. These characteristics indicate that the BhPheDH possesses better thermostability,
ammonium chloride tolerance, halophilic mechanism, and high
salt activation. The mechanism of thermostability and high salt tolerance of the BhPheDH was analyzed by molecular dynamics simulation. These results provide useful information about the
enzyme with high-temperature activity, thermostability, halophilic mechanism, tolerance to high concentration of
ammonium chloride, higher
salt activation and enantio-selectivity, and the application of molecular dynamics simulation in analyzing the mechanism of these distinctive characteristics.