Characterization of cerium (III) ion binding to surface-immobilized EF-hand loop I of calmodulin

Cerium has a wide range of current and emerging applications, and the binding of cerium ions to solid substrates is important for cerium recovery, or in advanced material synthesis. In this study, we investigate the affinity of a surface-bound peptide derived from the EF-hand loop I of calmodulin for cerium (III) ions and compare the results to a scrambled control. Results obtained via quartz crystal microbalance with dissipation are used to estimate the dissociation constant between the bound EFhand loop I peptide and cerium (III) ions (1.3 ± 0.1 μM), which is comparable with other dissociation constants measured for EF-hand peptides and cerium ions in solution reported this work and in literature (0.95-5.8 μM). Circular dichroism also suggests that the peptide binds to cerium (III) ions in solution, and undergoes a secondary structural change upon binding. Overall, this study shows that EF-hand loop peptides are capable of binding cerium (III) ions in solution and when attached to a solid substrate.