咪唑和吡啶离子液体对青霉素酰化酶催化性能的影响

Effects of Imidazole-and Pyridine-based Ionic Liquids on Catalysis Performance of Immobilized Penicillin Acylase

采用两步法合成并表征了阳离子不同的咪唑型和吡啶型离子液体[C4mim]BF4,[C7mim]BF4,[C4pyr]BF4和[C7pyr]BF4,并将其应用于固定化青霉素G酰化酶(ImPGA)催化分解青霉素G钾盐的反应,考察了阳离子对酶活性、稳定性、动力学的影响,及ImPGA在不同离子液体中酶活性受底物(青霉素G钾盐)抑制情况.结果表明,ImPGA在[C7pyr]BF4,[C4pyr]BF4和[C7mim]BF4中活性依次降低,在亲水性较强的[C4mim]BF4中易失去活性,其在3种离子液体中37℃下保存30min活性没有降低,米氏常数Km依次为752.15,160.57和62.74mmol/L,最大反应速率Vmax依次为0.204,0.042和0.024mmol/(g·min);底物浓度为26.85～295.32mmol/L时酶活性不受底物抑制.

In order to investigate the effect of cations of ionic liquids on catalysis performance of immobilized penicillin G acylase （ImPGA）. Four kinds of imidazole-and pyridine-based ionic liquids through two-step strategy,[C4mim]BF4,[C7mim]BF4,[C4pyr]BF4 and [C7pyr]BF4 were synthesized and characterized. The hydrolysis of penicillin G potassium catalyzed by ImPGA was conducted in these ionic liquids. Enzyme activity,stability and kinetics of ImPGA were studied. Substrate inhibition of ImPGA under different substrate concentrations was also detected. The results showed that the activity of ImPGA decreased in the order of [C7pyr]BF4[C4pyr]BF4[C7mim]BF4. ImPGA lost its activity in [C4mim]BF4 because of high hydrophilicity of the media. Enzyme activity of ImPGA could be maintained after incubation in ionic liquids at 37℃ for 30 min in the former three ionic liquids. Two kinetic parameters,Km and Vmax,of the reaction decreased followed the order [C7pyr]BF4[C4pyr]BF4[C7mim]BF4. Enzyme activity was not inhibited by substrate at the concentration of 75.17～85.91 mmol/L.