Titre : Light-driven P450 biocatalysts featuring Ru(II)-polypyridyl complexes
Endroit: Pavillon Roger-Gaudry, Salle G-715
Hôte : Prof. Joelle Pelletier
Résumé : The Cytochromes P450 are heme-thiolate enzymes that carry out
selective oxyfunctionalization of a wide range of substrates C-H bonds
using molecular dioxygen and two reducing equivalents. Recent efforts
have focused on the use of light-harvesting units to trigger P450 activity
upon visible light excitation. Our laboratory has taken advantage of
Ru(II)-diimine complexes and their unique excited properties to harness
the P450 synthetic potential. The covalent attachment of these
photosensitizers to non-native single cysteine residues has enabled
rapid electron injections into the heme domain of several bacterial P450
enzymes leading to high photocatalytic activity and coupling efficiency.
The crystal structure of the most efficient hybrid enzyme reveals that the
photosensitizer is ideally positioned to deliver electrons to the heme
active site utilizing the natural electron transfer pathway. A combination
of rational and directed evolution approaches are currently employed to
optimize the biocatalyst photocatalytic activity and expand the scope of
the light-driven P450 activity. In addition, we recently sought to capitalize
on the photoredox properties of these inorganic complexes combined
with the P450 biocatalysis to develop novel chemoenzymatic
approaches including selective light-driven trifluoromethylation/
oxyfunctionalization of several substituted arenes.
