Issue 16, 2023

Iridium(iii) polypyridine artificial metalloenzymes with tunable photophysical properties: a new platform for visible light photocatalysis in aqueous solution

Abstract

Artificial metalloenzymes (ArMs) can combine the unique features of both metal complexes and enzymes by incorporating a cofactor within a protein scaffold. Herein, we describe a panel of ArMs constructed by covalently linking Ir(III) polypyridyl complexes into a prolyl oligopeptidase scaffold. Spectroscopic methods were used to examine how properties of the resulting ArMs are influenced by structural variation of the cyclometalated ligands and the protein scaffold. Visible light photocatalysis by these hybrid catalysts was also examined, leading to the finding that they catalyze inter/intra-molecular [2 + 2] photocycloaddition in aqueous solution. Low but reproducible enantioselectivity was observed using a cofactor that undergoes partial kinetic resolution upon bioconjugation within the ArM active site, showing the importance of scaffold/cofactor interactions for enabling selective ArM photocatalysis. Further evidence of the importance of cofactor/scaffold interactions was provided by analyzing native POP peptidase catalysis by the ArMs. Together, these studies show how Ir(III)-based ArMs constitute a promising starting point for ongoing studies to control the stereoselectivity of EnT reactions by engineering substrate binding/activation motifs in POP.

Graphical abstract: Iridium(iii) polypyridine artificial metalloenzymes with tunable photophysical properties: a new platform for visible light photocatalysis in aqueous solution

Supplementary files

Article information

Article type
Communication
Submitted
27 Mar 2023
Accepted
30 Mar 2023
First published
31 Mar 2023

Dalton Trans., 2023,52, 5034-5038

Author version available

Iridium(III) polypyridine artificial metalloenzymes with tunable photophysical properties: a new platform for visible light photocatalysis in aqueous solution

B. Liu, Y. S. Zubi and J. C. Lewis, Dalton Trans., 2023, 52, 5034 DOI: 10.1039/D3DT00932G

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