3 publications

3 publications

Catalytic Hydrogenation of Itaconic Acid in a Biotinylated Pyrphos-Rhodium(I) System in a Protein Cavity

Chan, A.S.C.

Tetrahedron: Asymmetry 1999, 10, 1887-1893, 10.1016/S0957-4166(99)00193-7

The construction of a chiral catalyst system embedded at a specific site in a protein has been studied. The preparation of the biotinylated Pyrphos–Rh(I) complex attached to the binding site in avidin and its application to the asymmetric hydrogenation of itaconic acid have been investigated. By introducing the chiral Pyrphos–Rh(I) moiety into the constrained environment of the protein cavity it was found that the enantioselectivity of the system was significantly influenced by the tertiary conformation within the avidin cavity. The effects of reaction conditions such as temperature, hydrogen pressure, and the pH value of the buffer on enantioselectivity are reported.


Metal: Rh
Ligand type: Phosphine
Host protein: Avidin (Av)
Anchoring strategy: Supramolecular
Optimization: ---
Reaction: Hydrogenation
Max TON: 31
ee: 48
PDB: ---
Notes: ---

Oxidation of Organic Molecules in Homogeneous Aqueous Solution Catalyzed by Hybrid Biocatalysts (Based on the Trojan Horse Strategy)

Mahy, J.-P.

Tetrahedron: Asymmetry 2010, 21, 1593-1600, 10.1016/j.tetasy.2010.03.050

New anionic metalloporphyrin–estradiol conjugates have been synthesized and fully characterized, and have been further associated to a monoclonal anti-estradiol antibody 7A3, to generate new artificial metalloenzymes following the so-called ‘Trojan Horse’ strategy. The spectroscopic characteristics and dissociation constants of these complexes were similar to those obtained for the artificial metalloproteins obtained by association of cationic metalloporphyrin–estradiol conjugates to 7A3. This demonstrates that the nature of the porphyrin substituents, anionic or cationic, had little influence on the association with the antibody that is mainly driven by the tight association of the estradiol anchor with the binding pocket of the antibody. These new biocatalysts appeared to have an interesting catalytic activity in oxidation reactions. The iron(III)–anionic-porphyrin–estradiol-antibody complexes were found able to catalyze the chemoselective and slightly enantioselective (ee = 10%) sulfoxidation of sulfides by H2O2. The Mn(III)–porphyrin–estradiol-antibody complexes were found to catalyze the oxidation of styrene by KHSO5, the Mn(III)–cationic-porphyrin–estradiol-antibody complexes even showing the highest yields so far reported for the oxidation of styrene catalyzed by artificial metalloproteins. However, a lack of chemoselectivity and enantioselectivity was observed, which was probably due to a weak interaction of the metalloporphyrin cofactor with the binding pocket of antibody 7A3, as suggested by the similar UV–visible characteristics and catalytic activities obtained with both anionic and cationic porphyrins.


Metal: Fe
Ligand type: Porphyrin
Host protein: Antibody 7A3
Anchoring strategy: Supramolecular
Optimization: ---
Reaction: Sulfoxidation
Max TON: 9
ee: 10
PDB: ---
Notes: ---

Metal: Mn
Ligand type: Porphyrin
Host protein: Antibody 7A3
Anchoring strategy: Supramolecular
Optimization: ---
Reaction: Epoxidation
Max TON: 105
ee: ---
PDB: ---
Notes: Imidazole as co-catalyst

Stereoselective Sulfoxidation Catalyzed by Achiral Schiff Base Complexes in the Presence of Serum Albumin in Aqueous Media

Bian, H.-D.; Huang, F.-P.

Tetrahedron: Asymmetry 2017, 28, 1700-1707, 10.1016/j.tetasy.2017.10.021

Four coordination complexes ML derived from an achiral Schiff base ligand (H2L = 2,2′-[(1,2-ethanediyl)bis(nitrilopropylidyne)]bisphenol) have been synthesized and characterized. A method is described for the enantioselective oxidation of a series of aryl alkyl sulfides using the coordination complexes in the presence of serum albumins (SAs) in an aqueous medium at ambient temperature. The mixture of metal complexes with serum albumins is useful for inducing asymmetric catalysis. The complex, albumin source and substrate influence stereoselective sulfoxidation. At optimal pH with the appropriate oxidant, some of ML/SA systems are identified as very efficient catalysts, giving the corresponding sulfoxides in excellent chemical yield (up to 100%) and good enantioselectivity (up to 94% ee) in certain cases. UV–visible spectroscopic data provide evidence that stronger binding between the complex and serum albumin lead to higher enantioselectivity.


Metal: Co
Anchoring strategy: Undefined
Optimization: ---
Reaction: Sulfoxidation
Max TON: ~60
ee: 59
PDB: ---
Notes: ---