Ricoux, R.

Chem. Eur. J. 2020, 26, 14929-14937, 10.1002/chem.202002434

A novel inducible artificial metalloenzyme obtained by covalent attachment of a manganese(III)-tetraphenylporphyrin (MnTPP) to the artificial bidomain repeat protein, (A3A3′)Y26C, is reported. The protein is part of the αRep family. The biohybrid was fully characterized by MALDI-ToF mass spectrometry, circular dichroism and UV/Vis spectroscopies. The peroxidase and monooxygenase activities were evaluated on the original and modified scaffolds including those that have a) an additional imidazole, b) a specific αRep bA3-2 that is known to induce the opening of the (A3A3′) interdomain region and c) a derivative of the αRep bA3-2 inducer extended with a His6-Tag (His6-bA3-2). Catalytic profiles are highly dependent on the presence of co-catalysts with the best activity obtained with His6-bA3-2. The entire mechanism was rationalized by an integrative molecular modeling study that includes protein–ligand docking and large-scale molecular dynamics. This constitutes the first example of an entirely artificial metalloenzyme with inducible peroxidase and monooxygenase activities, reminiscent of allosteric regulation of natural enzymatic pathways.

Mahy, J.-P.; Ricoux, R.

ChemBioChem 2016, 17, 433-440, 10.1002/cbic.201500445

A new artificial enzyme formed by associating NCS‐3.24 with a copper complex catalyzed the Diels–Alder cyclization of cyclopentadiene with 2‐azachalcone and led to an increase in the formation of the exo‐products. Molecular modeling proposed the preferred relative positioning of both the Trojan horse complex and the two substrates.

Mahy, J.-P.; Ricoux, R.

ChemBioChem 2012, 13, 240-251, 10.1002/cbic.201100659

Enantioselective epoxidation: An artificial metalloenzyme obtained by noncovalent insertion of MnIII‐meso‐tetrakis(para‐carboxyphenyl)porphyrin Mn(TpCPP) into xylanase 10A from Streptomyces lividans as a host protein was able to catalyse the oxidation of para‐methoxystyrene by KHSO5 with a 16 % yield and the best enantioselectivity (80 % in favour of the R isomer) ever reported for an artificial metalloenzyme.

Mahy, J.-P.; Ricoux, R.

Dalton Trans. 2014, 43, 8344-8354, 10.1039/c4dt00151f

An anionic iron(III)-porphyrin–testosterone conjugate 1-Fe has been synthesized and fully characterized. It has been further associated with a neocarzinostatin variant, NCS-3.24, to generate a new artificial metalloenzyme following the so-called ‘Trojan Horse’ strategy. This new 1-Fe-NCS-3.24 biocatalyst showed an interesting catalytic activity as it was found able to catalyze the chemoselective and slightly enantioselective (ee = 13%) sulfoxidation of thioanisole by H2O2. Molecular modelling studies show that a synergy between the binding of the steroid moiety and that of the porphyrin macrocycle into the protein binding site can explain the experimental results, indicating a better affinity of 1-Fe for the NCS-3.24 variant than testosterone and testosterone-hemisuccinate themselves. They also show that the Fe-porphyrin complex is sandwiched between the two subdomains of the protein providing with good complementarities. However, the artificial cofactor entirely fills the cavity and its metal ion remains widely exposed to the solvent which explains the moderate enantioselectivity observed. Some possible improvements in the “Trojan Horse” strategy for obtaining better catalysts of selective oxidations are presented.

Mahy, J.-P.; Ricoux, R.

Bioorg. Med. Chem. 2014, 22, 5678-5686, 10.1016/j.bmc.2014.05.063

A new zinc(II)-cofactor coupled to a testosterone anchor, zinc(II)-N,N-bis(2-pyridylmethyl)-1,3-diamino-propa-2-ol-N′(17′-succinimidyltestosterone) (Zn-Testo-BisPyPol) 1-Zn has been synthesized and fully characterized. It has been further associated with a neocarzinostatin variant, NCS-3.24, to generate a new artificial metalloenzyme following the so-called ‘Trojan horse’ strategy. This new 1-Zn-NCS-3.24 biocatalyst showed an interesting catalytic activity as it was found able to catalyze the hydrolysis of the RNA model HPNP with a good catalytic efficiency (kcat/KM = 13.6 M−1 s−1 at pH 7) that places it among the best artificial catalysts for this reaction. Molecular modeling studies showed that a synergy between the binding of the steroid moiety and that of the BisPyPol into the protein binding site can explain the experimental results, indicating a better affinity of 1-Zn for the NCS-3.24 variant than testosterone and testosterone-hemisuccinate themselves. They also show that the artificial cofactor entirely fills the cavity, the testosterone part of 1-Zn being bound to one the two subdomains of the protein providing with good complementarities whereas its metal ion remains widely exposed to the solvent which made it a valuable tool for the catalysis of hydrolysis reactions, such as that of HPNP. Some possible improvements in the ‘Trojan horse’ strategy for obtaining better catalysts of selective reactions will be further studied.