Eu^(3+)对过氧化氢酶生物催化活性的影响

Effect of Eu^(3+) on Biocatalytic Activity of Catalase

采用紫外-可见(UV-V is)吸收光谱、同步荧光光谱和电化学方法研究了Eu3+与过氧化氢酶(CAT)的相互作用。结果表明,由于稀土离子易与O键合,因此,Eu3+主要与CAT肽链上的氨基酸残基中的羰基氧配位,引起肽链构象的变化,而构象的变化又会诱导CAT中的血红素结构的变化。当Eu3+浓度低时,Eu3+与CAT发生相互作用能使血红素的非平面性增加,转而使血红素中活性中心Fe(Ⅲ)的暴露程度增加,因此,使CAT的电化学活性和对H2O2还原的电催化活性提高。但当Eu3+的浓度高时,Eu3+会使CAT中血红素的非平面性降低,使血红素中活性中心Fe(III)的暴露程度降低,因此,降低了CAT的电化学和生物电催化活性。这说明不同浓度的Eu3+对CAT生物活性的影响不同,所以选择适当浓度的Eu3+对植物的生长具有促进作用。

In order to understand the chemical mechanism of the increase in the output of plants by rare earth fertilizers,the interaction between Eu^3＋ and catalase（CAT） was investigated with the UV-Vis absorption spectroscopy,synchronous fluorescent spectroscopy and electrochemical method.The results indicate that Eu^3＋ mainly interacts with the carboxyl oxygen in the amino acid residues of the peptide chain of CAT because rare earth ions are easy to be coordinated with O,causing the change in the peptide conformation and in turn the change in the structure of the heme group of CAT.When the concentration of Eu^3＋ is low,the interaction between Eu^3＋ and CAT induce the non-planarity of the heme group of CAT and then increase the exposure extent of the active center,Fe（Ⅲ）,leading to the increase in the electrochemical activity and the bioelectrocatalytic activity of CAT for the H2O2 reduction.However,when the concentration of Eu^3＋ is high,Eu^3＋ would decrease the non-planarity of the heme group and the exposure extent of Fe（Ⅲ）,leading to the decrease in the electrochemical and the bioelectrocatalytic activities of CAT.These results illustrate that the effects of the different concentrations of Eu^3＋ on the bioactivity of CAT are different.Therefore,selecting the suitable concentration of Eu^3＋ can promote the growth of plants.