辣根过氧化物酶在亲水性离子液体中的活性与稳定性研究

Activity and Thermal Stability of Horseradish Peroxidase in Ionic Liquids

基于辣根过氧化物酶对过氧化氢氧化愈创木酚这个显色反应的催化作用,研究了辣根过氧化物酶在七种亲水性离子液体[C2mim][BF4]、[C4mim][BF4]、[C6mim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3、[C4mim][CF3CO2]中的活性与稳定性变化.结果表明辣根过氧化物酶在不同离子液体中均有不同程度的失活,辣根过氧化物酶活性随离子液体极性增强而降低.辣根过氧化物酶在含[C4mim]Cl离子液体的介质中,随着温度升高,[C4mim]Cl对辣根过氧化物酶的失活过程起加速作用,离子液体浓度越高,酶的热稳定性越差.紫外-可见光谱研究表明,在含[Cnmim][BF4]、[C4mim]HSO4、[C4mim]Cl、[C4mim]NO3的介质中,辣根过氧化物酶血红素中心最大吸收峰没有发生变化,但吸收值增强,证明离子液体使酶的血红素基团暴露于介质中而增强了吸收;而在含[C4mim][CF3CO2]的介质中,辣根过氧化物酶血红素基团最大吸收峰区发生蓝移,证明有部分血红素基团被离子液体破坏而脱落.

The activity and thermal stability of horseradish peroxidase were investigated in [C2mim ] [ BF4 ]、 [ C4mim ] [ BF4 ], [ C6mim ] [ BF4 ]、 [ C4mim ] HSO4, [ C4mim ] Cl、 [ C4mim ] NO3, [ C4mim ] [ CF3CO2 ] / phosphate buffer mixtures. Horseradish peroxidase＇s activity decreased with increasing the polarity of the ionic liquids. Thermal deactivation kinetics of horseradish peroxidase were studied from 45℃ to 60℃ in 40%, 80% （w/v） 1-butyl- 3-methylimidazolium chloride [ C4mim] C1. Activity of horseradish peroxidase accelerated decreased with increasing temperature and ionic liquids concentration. UV-visible spectrophotometer analysis demonstrates that ionic liquid had an obvious effect on conformation of horseradish peroxidase. The λmax of heme were increased with no blue-shift in the [ Cnmim ] [ BF4 ], [ C4mim ] HSO4 , [ C4mim ] Cl, [ C4 mim ] NO3-containing systems, which demonstrated that some hemes exposured to the medium. While a blue-shift of λmax of heme took place in the systems involving [ C4miml [ CF3CO2 ], which demonstrated that some hemes were destroyed and separated from HRP.