Electrochemistry of Eu(III) Binding to N-terminal of Euplotes Octocarinatus Centrin

Abstract

Ciliate Euplotes octocarinatus centrin (EoCen) is a member of the EF-hand super family of calcium-binding proteins, which is associated with the centrosomes. In this work, the interaction between N-terminal of EoCen (N-EoCen) and Eu 3+ was investigated by cyclic voltammetry and UV-Vis spectroscopies. The result shows that a 2:1 of Eu 3+ to N-EoCen complex (Eu 2 -N-EoCen) is formed. The electrochemical characteristics of Eu 2 -N-EoCen at a multi-wall carbon nanotube/Nafion composite film modified glassy carbon electrode (MWNT/Nafion/GCE) were then investigated in detail, from which a direct, quasi reversible electron transfer of Eu 2 -N-EoCen had been obtained. According to the Laviron diffusionless-controled equations, the electron transfer rate constant k s , was calculated to be 2.33 + 0.14 s −1 . The pH dependence of the formal potential of Eu 2 -N-EoCen suggests that protonation accompanies electron transfer between pH 5.5-7.4. The electrochemical redox and quantitative analysis of Eu 2 -NEoCen are therefore of great significance not only studying the physiological processes of Eu 2 -N-EoCen in organisms but also the interaction mechanism with target protein.

Comparative Electrochemical Study of N‐, C‐terminal and Integral Centrin on Adsorption and Metal‐Binding Properties

“…N‐EoCen has strong adsorption on GC electrode surface . This character could be used to fabricate protein modified electrode, by which the interactions between the Ln 3+ and N‐EoCen have been characterized by a series of EIS, CV , . This novel electrochemical method with reflecting the structural change of protein on the surface of the GC electrode can be further used to detect the interactions of C‐EoCen and EoCen with Eu 3+ at GC electrodes.…”