A Highly Active Biohybrid Catalyst for Olefin Metathesis in Water: Impact of a Hydrophobic Cavity in a β-Barrel Protein
A series of Grubbs–Hoveyda type catalyst precursors for olefin metathesis containing a maleimide moiety in the backbone of the NHC ligand was covalently incorporated in the cavity of the β-barrel protein nitrobindin. By using two protein mutants with different cavity sizes and choosing the suitable spacer length, an artificial metalloenzyme for olefin metathesis reactions in water in the absence of any organic cosolvents was obtained. High efficiencies reaching TON > 9000 in the ROMP of a water-soluble 7-oxanorbornene derivative and TON > 100 in ring-closing metathesis (RCM) of 4,4-bis(hydroxymethyl)-1,6-heptadiene in water under relatively mild conditions (pH 6, T = 25–40 °C) were observed.
ROMP (cis/trans: 48/52)
A Rhodium Complex-Linked β-Barrel Protein as a Hybrid Biocatalyst for Phenylacetylene Polymerization
Our group recently prepared a hybrid catalyst containing a rhodium complex, Rh(Cp)(cod), with a maleimide moiety at the peripheral position of the Cp ligand. This compound was then inserted into a β-barrel protein scaffold of a mutant of aponitrobindin (Q96C) via a covalent linkage. The hybrid protein is found to act as a polymerization catalyst and preferentially yields trans-poly(phenylacetylene) (PPA), although the rhodium complex without the protein scaffold normally produces cis PPA.
Construction of a Hybrid Biocatalyst Containing a Covalently-Linked Terpyridine Metal Complex within a Cavity of Aponitrobindin
Manganese Terpyridine Artificial Metalloenzymes for Benzylic Oxygenation and Olefin Epoxidation