Boosting the Peroxidase-like Activity of Cobalt Ions by Amino Acid-based Biological Species and Its Applications.

Enzyme mimics have been widely used as alternatives to natural enzymes, owing to their high stability and low cost. However, the activity and atom economy of enzyme mimics still need to be improved. Herein, we report the boosting effects of amino acids, peptides and proteins on the peroxidase-like activity of Co2+ . Among 20 amino acids, tryptophan (Trp) enhanced the activity of Co2+ approximately 8 times and was identified as the best stimulator. The study revealed the synergy of amino acids-based species and HCO3 - for efficient catalysis. Co2+ is proposed to bind simultaneously to HCO3 - and Trp, and to form a ternary catalyst which facilitates the generation of reactive oxygen species. Based on the selective boosting by Trp, a simple and low-cost Co2+ sensor with high sensitivity was developed, which showed a linear range of 10-300 μM and a limit of detection of 0.4 μM for Co2+ .