7 publications

7 publications

Abiological Catalysis by Artificial Haem Proteins Containing Noble Metals in Place of Iron

Hartwig, J. F.

Nature, 2016, 10.1038/nature17968

Enzymes that contain metal ions—that is, metalloenzymes—possess the reactivity of a transition metal centre and the potential of molecular evolution to modulate the reactivity and substrate-selectivity of the system1. By exploiting substrate promiscuity and protein engineering, the scope of reactions catalysed by native metalloenzymes has been expanded recently to include abiological transformations2,3. However, this strategy is limited by the inherent reactivity of metal centres in native metalloenzymes. To overcome this limitation, artificial metalloproteins have been created by incorporating complete, noble-metal complexes within proteins lacking native metal sites1,4,5. The interactions of the substrate with the protein in these systems are, however, distinct from those with the native protein because the metal complex occupies the substrate binding site. At the intersection of these approaches lies a third strategy, in which the native metal of a metalloenzyme is replaced with an abiological metal with reactivity different from that of the metal in a native protein6,7,8. This strategy could create artificial enzymes for abiological catalysis within the natural substrate binding site of an enzyme that can be subjected to directed evolution. Here we report the formal replacement of iron in Fe-porphyrin IX (Fe-PIX) proteins with abiological, noble metals to create enzymes that catalyse reactions not catalysed by native Fe-enzymes or other metalloenzymes9,10. In particular, we prepared modified myoglobins containing an Ir(Me) site that catalyse the functionalization of C–H bonds to form C–C bonds by carbene insertion and add carbenes to both β-substituted vinylarenes and unactivated aliphatic α-olefins. We conducted directed evolution of the Ir(Me)-myoglobin and generated mutants that form either enantiomer of the products of C–H insertion and catalyse the enantio- and diastereoselective cyclopropanation of unactivated olefins. The presented method of preparing artificial haem proteins containing abiological metal porphyrins sets the stage for the generation of artificial enzymes from innumerable combinations of PIX-protein scaffolds and unnatural metal cofactors to catalyse a wide range of abiological transformations.


Metal: Ir
Ligand type: Methyl; Porphyrin
Host protein: Myoglobin (Mb)
Anchoring strategy: Metal substitution
Optimization: Chemical & genetic
Reaction: C-H activation
Max TON: 7260
ee: 68
PDB: ---
Notes: ---

Metal: Ir
Ligand type: Methyl; Porphyrin
Host protein: Myoglobin (Mb)
Anchoring strategy: Metal substitution
Optimization: Chemical & genetic
Reaction: C-H activation
Max TON: 92
ee: 84
PDB: ---
Notes: ---

An asymmetric catalyst

Akabori, S.; Sakurai, S.

Nature, 1956, 10.1038/178323b0

Asymmetric synthesis has hitherto succeeded only by using reagents or solvents having the asymmetric configuration.


Metal: Pd
Ligand type: Undefined
Host protein: Silk fibroin fibre
Anchoring strategy: Undefined
Optimization: ---
Reaction: Hydrogenation
Max TON: >22
ee: ---
PDB: ---
Notes: ---

Design of Functional Metalloproteins

Review

Lu, Y.

Nature, 2009, 10.1038/nature08304


Notes: ---

Directed Evolution of Artificial Metalloenzymes for In Vivo Metathesis

Panke, S.; Ward, T. R.

Nature, 2016, 10.1038/nature19114


Metal: Ru
Ligand type: Carbene
Host protein: Streptavidin (Sav)
Anchoring strategy: Supramolecular
Optimization: Genetic
Reaction: Olefin metathesis
Max TON: 610
ee: ---
PDB: ---
Notes: Reaction in the periplasm

Metal Ion Dependent Binding of Sulphonamide to Carbonic Anhydrase

Coleman, J. E.

Nature, 1967, 10.1038/214193a0


Metal: Co
Ligand type: Amino acid
Host protein: Human carbonic anhydrase
Anchoring strategy: Metal substitution
Optimization: ---
Max TON: ---
ee: ---
PDB: ---
Notes: CO2 hydration

Metal: Co
Ligand type: Amino acid
Host protein: Human carbonic anhydrase
Anchoring strategy: Metal substitution
Optimization: ---
Max TON: ---
ee: ---
PDB: ---
Notes: Ester cleavage

Rational Design of a Structural and Functional Nitric Oxide Reductase

Lu, Y.

Nature, 2009, 10.1038/nature08620


Metal: Fe
Ligand type: Amino acid
Host protein: Myoglobin (Mb)
Anchoring strategy: Dative
Optimization: Genetic
Reaction: NO reduction
Max TON: ~5
ee: ---
PDB: 3K9Z
Notes: Design of a catalytically active non-haem iron-binding site (FeB) in sperm whale myoglobin.

Selection and Evolution of Enzymes from a Partially Randomized Non-Catalytic Scaffold

Seelig, B.; Szostak, J. W.

Nature, 2007, 10.1038/nature06032


Metal: Zn
Ligand type: Amino acid
Anchoring strategy: Dative
Optimization: Genetic
Reaction: RNA ligation
Max TON: >7
ee: ---
PDB: ---
Notes: ---