6 publications

6 publications

A Highly Active Biohybrid Catalyst for Olefin Metathesis in Water: Impact of a Hydrophobic Cavity in a β-Barrel Protein

Okuda, J.

ACS Catal. 2015, 5, 7519-7522, 10.1021/acscatal.5b01792

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.


Metal: Ru
Ligand type: Carbene
Host protein: Nitrobindin (Nb)
Anchoring strategy: Covalent
Optimization: Chemical
Reaction: Olefin metathesis
Max TON: 9900
ee: ---
PDB: ---
Notes: ROMP (cis/trans: 48/52)

Metal: Ru
Ligand type: Carbene
Host protein: Nitrobindin (Nb)
Anchoring strategy: Covalent
Optimization: Chemical
Reaction: Olefin metathesis
Max TON: 100
ee: ---
PDB: ---
Notes: RCM

A Hybrid Ring- Opening Metathesis Polymerization Catalyst Based on an Engineered Variant of the Beta-Barrel Protein FhuA

Okuda, J.; Schwaneberg, U.

Chem. - Eur. J. 2013, 19, 13865-13871, 10.1002/chem.201301515

A β‐barrel protein hybrid catalyst was prepared by covalently anchoring a Grubbs–Hoveyda type olefin metathesis catalyst at a single accessible cysteine amino acid in the barrel interior of a variant of β‐barrel transmembrane protein ferric hydroxamate uptake protein component A (FhuA). Activity of this hybrid catalyst type was demonstrated by ring‐opening metathesis polymerization of a 7‐oxanorbornene derivative in aqueous solution.


Metal: Ru
Ligand type: Carbene
Host protein: FhuA ΔCVFtev
Anchoring strategy: Covalent
Optimization: Chemical
Reaction: Olefin metathesis
Max TON: 955
ee: ---
PDB: ---
Notes: ROMP

Artificial Diels–Alderase based on the Transmembrane Protein FhuA

Okuda, J.

Beilstein J. Org. Chem. 2016, 12, 1314-1321, 10.3762/bjoc.12.124

Copper(I) and copper(II) complexes were covalently linked to an engineered variant of the transmembrane protein Ferric hydroxamate uptake protein component A (FhuA ΔCVFtev). Copper(I) was incorporated using an N-heterocyclic carbene (NHC) ligand equipped with a maleimide group on the side arm at the imidazole nitrogen. Copper(II) was attached by coordination to a terpyridyl ligand. The spacer length was varied in the back of the ligand framework. These biohybrid catalysts were shown to be active in the Diels–Alder reaction of a chalcone derivative with cyclopentadiene to preferentially give the endo product.


Metal: Cu
Ligand type: Terpyridine
Host protein: FhuA
Anchoring strategy: Cystein-maleimide
Optimization: Chemical
Max TON: ---
ee: ---
PDB: ---
Notes: ---

Hybrid Ruthenium ROMP Catalysts Based on an Engineered Variant of β-Barrel Protein FhuA ΔCVFtev: Effect of Spacer Length

Okuda, J.

Chem. - Asian J. 2015, 10, 177-182, 10.1002/asia.201403005

A biohybrid ring‐opening olefin metathesis polymerization catalyst based on the reengineered β‐barrel protein FhuA ΔCVFtev was chemically modified with respect to the covalently anchored Grubbs–Hoveyda type catalyst. Shortening of the spacer (1,3‐propanediyl to methylene) between the N‐heterocyclic carbene ligand and the cysteine site 545 increased the ROMP activity toward a water‐soluble 7‐oxanorbornene derivative. The cis/trans ratio of the double bond in the polymer was influenced by the hybrid catalyst.


Metal: Ru
Ligand type: Carbene
Host protein: FhuA ΔCVFtev
Anchoring strategy: Covalent
Optimization: Chemical
Reaction: Olefin metathesis
Max TON: 555
ee: ---
PDB: ---
Notes: ROMP; cis/trans = 58/42

Metatheases: Artificial Metalloproteins for Olefin Metathesis

Review

Okuda, J.

Org. Biomol. Chem. 2016, 14, 9174-9183, 10.1039/C6OB01475E

The incorporation of organometallic catalyst precursors in proteins results in so-called artificial metalloenzymes. The protein structure will control activity, selectivity and stability of the organometallic site in aqueous medium and allow non-natural reactions in biological settings. Grubbs-Hoveyda type ruthenium catalysts with an N-heterocyclic carbene (NHC) as ancillary ligand, known to be active in olefin metathesis, have recently been incorporated in various proteins. An overview of these artificial metalloproteins and their potential application in olefin metathesis is given.


Notes: ---

Olefin Metathesis Catalysts Embedded in β-Barrel Proteins: Creating Artificial Metalloproteins for Olefin Metathesis

Review

Okuda, J.; Sauer, D.F.

Beilstein J. Org. Chem. 2018, 14, 2861-2871, 10.3762/bjoc.14.265

This review summarizes the recent progress of Grubbs–Hoveyda (GH) type olefin metathesis catalysts incorporated into the robust fold of β-barrel proteins. Anchoring strategies are discussed and challenges and opportunities in this emerging field are shown from simple small-molecule transformations over ring-opening metathesis polymerizations to in vivo olefin metathesis.


Notes: ---