Superactivity <i>of</i> Bimetallic CuFeO₂ Submicron Particles towards Selective Proteolysis, Depending on their <i>Surface Hydroxyls</i>

Nano bimetallic oxides as nanoproteases have the great advantages in the heterogeneous hydrolysis of proteins. Here, we report that bimetallic delafossite CuFeO₂ submicron particles (CuFeO₂ SMPs) display a high protease activity towards selective cleavage of peptide bond involving hydrophobic residue at 25 °C. CuFeO₂ SMPs have excellent regeneration performance with high structural stability. The strong Lewis acidity of Fe³⁺ and the strong nucleophilicity of Cu⁺ bound hydroxyl groups are both necessary for the high protease activity of CuFeO₂ SMPs. Low-valent metal ion has a great advantage in that low-valent Cu⁺ bound hydroxyl has strong nucleophilicity, resulting in promotion of protein hydrolysis via high-efficient bimetallic catalysis. This study provides evidence that the protease activity of CuFeO₂ SMPs depends on metal ion-bound hydroxyls on their surface. Our findings highlight that the valence of metal ions in artificial protease and their surface hydroxyls are two important factors that determine their catalytic efficiency.