Abstract:

In order to understand the chemical mechanism of the increase in the output of plants by rare earth fertilizers, the interaction between Eu3+ and catalase (CAT) was investigated with the UV-Vis absorption spectroscopy, synchronous fluorescent spectroscopy and electrochemical method. The results indicated that Eu3+ mainly interacts with the carbonyl oxygen in the amino acid residues of the peptide chain of CAT because rare earth ions are easy to coordinate 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 Eu3+ is low the interaction between Eu3+ and CAT would introduce the increase in the non-planarity of the heme group of CAT and then the increase in 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 Eu3+ is high Eu3+ would decrease the non-planarity of the heme group and then the exposure extent of Fe(III), leading to the decrease in the electrochemical and the bioelectrocatalytic activities of CAT. These results illustrated that the effects of the different concentration of Eu3+ on the bioactivity of CAT are different. Therefore, selecting the suitable concentration of Eu3+ can promote the growth of plants.

Key words: Catalase, Europium, Hydrogen peroxide, Bioelectrocatalytic activity, Conformation