Design of Polyproline-Based Catalysts for Ester Hydrolysis

A number of simple oligopeptides have been recently developed as minimalistic catalysts for mimicking the activity and selectivity of natural proteases. Although the arrangement of amino acid residues in natural enzymes provides a strategy for designing artificial enzymes, creating catalysts with efficient binding and catalytic activity is still challenging. In this study, we used the polyproline scaffold and designed a series of 13-residue peptides with a catalytic dyad or triad incorporated to serve as artificial enzymes. Their catalytic efficiency on ester hydrolysis was evaluated by ultraviolet-visible spectroscopy using the p-nitrophenyl acetate assay, and their secondary structures were also characterized by circular dichroism spectroscopy. The results indicate that a well-formed polyproline II structure may result in a much higher catalytic efficiency. This is the first report to show that a functional dyad or triad engineered into a polyproline helix framework can enhance the catalytic activity on ester hydrolysis. Our study has also revealed the necessity of maintaining an ordered structure and a well-organized catalytic site for effective biocatalysts.