Designed imidazole-based supramolecular catalysts for accelerating oxidation/hydrolysis cascade reactions

Reconstructing enzymatic active sites presents a significant challenge due to the intricacies involved in achieving enzyme-like scaffold folding and spatial arrangement of essential functional groups.There is also a growing interest in building biocatalytic networks,wherein multiple enzymatic active sites are localized within a single artificial system,allowing for cascaded transformations.In this work,we report the self-assembly of imidazole or its derivatives with fluorenylmethyloxycarbonyl-modified histidine and Cu2+to fabricate a supramolecular catalyst,which possesses catechol oxidase-like dicopper center with multiple imidazole as the coordination sphere.Transmission electron microscopy,low-temperature X-band continuous-wave electron paramagnetic resonance,K-edge X-ray absorption spectra/the extended X-ray absorption fine structure analysis,and density functional theory modeling were used for the structural characterization of the catalyst.The phenol derivatives and the dissolved oxygen were used as the substrates,with the addition of 4-aminoantipyrine to generate a red adduct with a maximum absorbance at 510 nm,for obtaining time-dependent absorbance change curves and estimating the activities.The results reveal that the addition of imidazole synergistically accelerates the oxidative activity about 10-fold and the hydrolysis activity about 14-fold than fluorenylmethyloxycarbonyl modified-histidine/Cu2+.The supramolecular nanoassembly also exhibits the ability to catalyze oxidation/hydrolysis cascade reactions,converting 2′,7′-dichlorofluorescin diacetate into 2′,7′-dichlorofluorescein.This process can be regulated through the methylation of the imidazole component at various positions.This work may contribute to the design of advanced biomimetic catalysts,and shed light on early structural models of the active sites of the primitive copper-dependent enzymes.

The scaling behavior of the second virial coefficient of linear and ring polymer

The scaling behavior of the second virial coefficient of ring polymers at the theta temperature of the corresponding linear polymer(θ_L) is investigated by off-lattice Monte Carlo simulations. The effects of the solvents are modeled by pairwise interaction between polymer monomers in this approach. Using the umbrella sampling, we calculate the effective potential U(r) between two ring polymers as well as the second virial coefficient A_2 of ring polymers at θ_L, which results from a combination of 3-body interactions and topological constraints. The trend in the strength of the effective potential with respect to chain length shows a non-monotonic behavior, differently from that caused only by topological constraints. Our simulation suggests that there are three regimes about the scaling behavior of A_2 of ring polymers at θ_L: 3-body interactions dominating regime, the crossover regime, and the topological constraints dominating regime.

Designed histidine-rich peptide self-assembly for accelerating oxidase-catalyzed reactions

It is an important goal for supramolecular chemistry to develop synthetic enzyme mimics rivaling native enzymes,while de novo fabrication of such mimics remains a challenge.Alternatively,the catalytic groups from the supramolecular complex can be integrated with the active sites of natural enzymes.Herein,we present a supramolecular catalytic hybrid that is self-assembled from oligohistidine-based peptides and a heme-dependent peroxidase.The results indicate that the peptides altered the enzyme conformation,promoted the transitions between the resting and the intermediate states of the heme,and increased the turnover rate of the enzyme by up to three-fold.We propose that the histidine residues from the peptides may collaborate with the groups in the natural heme pocket to accelerate the catalytic cycles of the enzyme.Our observations underline the advantages of the supramolecular approach and suggest that molecular self-assembly may combine with enzymes to provide a simple strategy to engineer the enzymatic active sites.

Erratum to:Designed imidazole-based supramolecular catalysts for accelerating oxidation/hydrolysis cascade reactions

Erratum to Nano Research,2024,17(6):4916−4923 https://doi.org/10.1007/s12274-024-6489-5 Labeling and statement of equal contribution of the authors Yuanxi Liu and Wenjie Xu were missed in the original article as well as the Electronic Supplementary Material.Superscript symbols of equal contribution“§”were added to both authors in the author list,and their contribution was stated as follows:“§Yuanxi Liu and Wenjie Xu contributed equally to this work.”