Cobalt de novo designed metallopeptides as artificial metalloenzyme in hydrogen production.

Spy protein is an artificial protein formed by a protein component (SpyCatcher, SC) which binds a specific peptidic sequence (SpyTag, ST). Our research group is involved into the redesign of the ST component to develop artificial catalytic metalloproteins. This project wants to determine the metal coordination sphere of cobalt ion when bound at the metal binding sites of STs and related reconstituted Spy proteins. We are looking to an ATCUN (Amino Terminal Nickel and Copper) binding site. Co(II/III) site is designed to operate catalytic reduction of H+ into H2. At the current stage, GC data demonstrates that these assemblies promote H2 evolution under photocatalytic conditions using Ru(bpy)3. Also, modifying a side chain of ATCUN motif we can impair or promote H2 production; even if it is not directly involve in the coordination. We believe that XAS characterization is essential to elucidate both coordination and oxidation states of Co in correlation with its catalytic behavior.