Stability and Pseudocatecholase Activity of Artificial Bis-Histidyl Copper Peptides

In this paper, 4-methylcatechol (4-MC) and L/D-Dopa are selected as target substrates for de novo protein design, serving as a proof-of-concept system for evaluating the catalytic activity of metal coordination sites. We report two novel water-soluble bis-histidyl peptides that exhibit catalytic activity, where structural constraints around the active site would play a pivotal role in metalloenzyme development. The particular tandem His–His motif in the peptides and favorable E0′ enable them to catalyze catechol oxidation reactions efficiently. The coordination behavior of the peptides with Cu(II) and Cu(I) ions is thoroughly investigated using a combination of analytical techniques, including potentiometric titration and fluorescence, ultraviolet–visible (UV–vis), and circular dichroism (CD) spectroscopies. The insights gained into the catalytic binding site and associated pseudocatecholase activity of these peptides contribute to the development of copper-based bioinspired artificial metalloenzymes.