维生素C对嗜酸乳杆菌GIM1.208 β-葡萄糖苷酶激活效应及分子互作关系

Effect of vitamin C on the activation of β-glucosidase in Lactobacillus acidophilus GIM1.208 and the interaction between them

摘要:

【背景】研究发现维生素C (vitamin C, VC)对嗜酸乳杆菌GIM1.208 β-葡萄糖苷酶(β-glucosidase, BGL)具有明显激活作用。【目的】探究VC对BGL的影响特性以及二者互作关系。【方法】通过对硝基苯酚法、电化学法、Zeta电位法及核磁共振氢谱法研究VC对BGL的活性影响及互作特性。【结果】VC对BGL催化底物活性具有明显促效作用，K_m=1.167 mmol/L，V_max随着VC浓度增大而增大；VC浓度为3.5%时酶活性达到最高；在VC浓度为3.5%、温度低于30 ℃时，酶活性受温度影响较小，VC对BGL具有良好的稳定作用，相对酶活保持在90%以上。VC与BGL结合，两者存在弱静电作用且两者的相互作用使得VC的电氧化反应变得更加容易，同时推测VC分子中乙二醇支链片段与BGL之间存在氢键作用。【结论】VC对BGL具有明显激活作用，试验探究了两者作用力类型及作用位点，为BGL应用及天然酶激活剂的高效利用提供设计理论参考。

Abstract:

[Background] A preliminary study showed that vitamin C (VC) had a significant activation effect on the β-glucosidase (BGL) from Lactobacillus acidophilus GIM1.208. [Objective] To explore the effect of VC on BGL and the interaction between VC and BGL. [Methods] The 4-nitrophenol method, electrochemistry, Zeta potential, and nuclear magnetic resonance were employed to study the effect of VC on BGL activity and the interaction characteristics. [Results] VC exerted a significant effect on the catalytic activity of BGL, with K_m=1.167 mmol/L, and the V_max increased with the increase in VC concentration. BGL presented the highest activity when the VC concentration was 3.5%. At the VC concentration of 3.5% and a temperature below 30 ℃, the BGL activity was barely affected by temperature, and VC had a good stabilizing effect on BGL, which showed the relative activity above 90%. VC can bind to BGL, and the weak electrostatic interaction between VC and BGL facilitated the electroxidation of VC. We hypothesized that there was a hydrogen bond between the ethylene glycol branch chain in VC molecule and BGL. [Conclusion] VC can activate BGL. We studied the type and site of interaction between VC and BGL, aiming to provide a theoretical reference for the application of BGL and the efficient utilization of natural enzyme activators.