Effect of ionic liquids on catalytic characteristics of hyperthermophilic and halophilic phenylalanine dehydrogenase and mechanism study

Biosynthesis of an unnatural amino acid, L-Homophenylalanine, by hyperthermophilic and halophilic phenylalanine dehydrogenase were studied. The catalytic characteristics of phenylalanine dehydrogenase from Natranaerobius thermophiles (NTAaDH) in the reaction systems involving ionic liquids (ILs) were examined. [EMIM]BF4 activated enzyme activity by 132%. Effect of several ionic liquids with different anions on enzyme activity was studied with associated conformational changes. Immobilization capacity of 0.550 mg/mg for NTAaDH was achieved. Kinetic parameters of reductive amination were calculated and compared. GO-PEI-ILs integrates beneficial characteristics of ionic liquids and polymers and enhanced the activity of NTAaDH. The mechanism of the effect of ionic liquids on GO-PEI for enzyme immobilization was investigated.