GIovanna Ghirlanda, Professor, School of Molecular Sciences, Arizona State University, will give a talk via Zoom on "Artificial metalloproteins by design."

ABSTRACT

Hybrid metalloproteins incorporating organometallic active sites not found in nature within a protein scaffold are emerging as a viable avenue to catalyze a wide range of reactions, with applications ranging from synthetic organic chemistry to sustainable fuel production. This approach is particularly appealing when coupled with light as a source of energy to drive the synthesis of clean energy sources. We have designed artificial enzymes capable of producing molecular hydrogen and reducing carbon dioxide to carbon monoxide and formate under irradiation with UV-vis light and in the presence of photosensitizers. The active site in these designs is either anchored to protein scaffolds using noncanonical amino acids, or obtained by swapping heme for cobalt protoporphyrin IX in natural and designed heme-binding proteins. Intriguingly, these constructs are active in aerobic conditions. We found that incorporation in a protein scaffold increases activity by 10-20 folds compared to the isolated organometallic complex. Transient spectroscopy analysis demonstrates that this effect correlates with increased lifetime of the catalytically active redox state. Current work examines the activity of these constructs within bacterial cells.