Artificial Metalloenzymes as Catalysts for Oxidative Lignin Degradation
We report novel artificial metalloenzymes (ArMs), containing tris(pyridylmethyl)amine (TPA), for the atom economic oxidation of lignin β-O-4 model compounds, using hydrogen peroxide. The protein scaffold alters the selectivity of the reaction from a low yielding cleavage reaction when using the parent Fe-tpa complex to a high yielding benzylic alcohol oxidation when using the complex incorporated into a protein scaffold, SCP-2L A100C. Engineering the protein scaffold to incorporate glutamic acid was found to improve the ArM activity, showing that rational design of the protein environment using metal binding amino acids can be a first step toward improving the overall activity of an artificial metalloenzyme.
Metal: FeLigand type: Tris(pyridylmethyl)amine (TPA)Host protein: Steroid Carrier Protein 2L (SCP 2L)Anchoring strategy: Cystein-maleimideOptimization: Chemical & geneticReaction: Lignin oxidationMax TON: 20ee: ---PDB: ---Notes: Reaction performed with a lignin model compound and hydrogen peroxide as oxidizing agent
Catalyst Design in Oxidation Chemistry; from KMnO4 to Artificial MetalloenzymesReview
Oxidation reactions are an important part of the synthetic organic chemist’s toolkit and continued advancements have, in many cases, resulted in high yields and selectivities. This review aims to give an overview of the current state-of-the-art in oxygenation reactions using both chemical and enzymatic processes, the design principles applied to date and a possible future in the direction of hybrid catalysts combining the best of chemical and natural design.