Peroxidase-like oxidative activity of a manganese-coordinated histidyl bolaamphiphile self-assembly

A peroxidase-like catalyst was constructed through the self-assembly of histidyl bolaamphiphiles coordinated to Mn²⁺ ions. The prepared catalyst exhibited oxidation activity for the organic substrate o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H₂O₂). The histidyl bolaamphiphiles of bis(N-alpha-amido-histidine)-1,7-heptane dicarboxylates self-assembled to make spherical structures in an aqueous solution. Subsequent association of Mn²⁺ ions with the histidyl imidazoles in the self-assembly produced catalytic active sites. The optimal Mn²⁺ ion concentration was determined and coordination of the Mn²⁺ ion with multiple histidine imidazoles was investigated using spectroscopy analysis. The activation energy of the produced catalysts was 55.0 kJ mol^-1, which was comparable to other peroxidase-mimetic catalysts. A detailed kinetics study revealed that the prepared catalyst followed a ping-pong mechanism and that the turnover reaction was promoted by increasing the substrate concentration. Finally, application of the prepared catalyst for glucose detection was demonstrated through cascade enzyme catalysis. This study demonstrated a facile way to prepare an enzyme-mimetic catalyst through the self-assembly of an amphiphilic molecule containing amino acid segments.