Biohybrid Catalyst Research Articles

Biocatalyseurs enzymatiques supportés dédiés à la production en continu de biodiesel

Modern societies are confronted to an increasing requirement of bio-fuels resources not of fossil origin. Biodiesels, obtained by transesterification of trimesters, are offering a real alternative. Transesterification can be catalyzed by enzymes such as lipases. We present the synthesis and use of enzyme-based macrocellular foams operating in continuous flow conditions. These monolithic biohybrid catalysts present several advantages, confinment of the enzymes, low steric hindrance, optimized mass transport, a rather simplicity in regard of the column in-situ synthetic path. Those features, concerning enzyme-based catalyzed transesterification, high enzymatic activity addressed with unprecedented endurance of continuous catalysis.

Self‐Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

AbstractBio‐nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self‐assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs affect the formation of the BNCs, and ultimately control the activity of the bound enzymes. Smaller MNPs form small clusters with a low affinity for the HRP. While the turnover for the bound fraction is drastically increased, there is no difference in the H2O2 inhibitory concentration. Larger MNPs with a higher magnetization aggregate in larger clusters and have a higher affinity for the enzyme and a lower substrate inhibition. All of the BNCs are more active than the free enzyme or the MNPs (BNCs > HRP ≫ MNPs). Since the BNCs show surprising resilience in various reaction conditions, they may pave the way towards new hybrid biocatalysts with increased activities and unique catalytic properties for magnetosensitive enzymatic reactions.

Incorporation of Manganese Complexes into Xylanase: New Artificial Metalloenzymes for Enantioselective Epoxidation

Here we report the best artificial metalloenzyme to date for the selective oxidation of aromatic alkenes; it was obtained by noncovalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into a host protein, xylanase 10A from Streptomyces lividans (Xln10A). Two metallic complexes-N,N'-ethylene bis(2-hydroxybenzylimine)-5,5'-dicarboxylic acid Mn(III) [(Mn-salen), 2-Mn] and 1-Mn-were associated with Xln10A, and the two hybrid biocatalysts were characterised by UV-visible spectroscopy, circular dichroism and molecular modelling. Only the artificial metalloenzyme based on 1-Mn and Xln10A was studied for its catalytic properties in the oxidation of various substituted styrene derivatives by KHSO(5): after optimisation, the 1-Mn-Xln10A artificial metalloenzyme was able to catalyse the oxidation of para-methoxystyrene by KHSO(5) with a 16 % yield and the best enantioselectivity (80 % in favour of the R isomer) ever reported for an artificial metalloenzyme.

Enzyme-based biohybrid foams designed for continuous flow heterogeneous catalysis and biodiesel production

The one-pot synthesis and use of monolithic biohybrid foams in a continuous flow device reported in here presents the advantages of covalent stabilization of the enzymes, together with a low steric hindrance between proteins and substrates, optimized mass transport due to the interconnected macroporous network and simplicity with regard to the column in situ synthetic path. Those features, when applied to transesterification (biodiesel production) via enzyme catalysis, provide among the top enzymatic activities displayed by biohybrid catalysts bearing unprecedented endurance of continuous catalysis for a two month period.

Enzyme-Based Hybrid Macroporous Foams as Highly Efficient Biocatalysts Obtained through Integrative Chemistry

Integrative chemistry-based rational design has been used to synthesize the first lipase [C-CRl]@Glymo-Si(HIPE) and [C-TAl]@Glymo-Si(HIPE) hybrid macrocellular biocatalysts, where immobilization of crude enzymes is optimized, while circumventing the reactants’ low kinetic diffusion, by the use of silica macroporous hosts. As a direct consequence, these new hybrid biocatalysts display unprecedented cycling catalysis performance, as demonstrated by the syntheses of butyloleate ester (used as biodiesel lubricant), hydrolysis of linoleic-glycero ester derivatives (end products used for detergent and soap generations), and trans-esterification (reaction involved in the synthesis of low viscosity biodiesel). Considering that the catalytic performances are given in terms of absolute conversion percentage and not just relative enzyme activity, the enzyme@Glymo-Si(HIPE) hybrid macrocellular biocatalysts presented in this study display unprecedented high yield cycling catalysis performances, where turnover numbers ...

Oxidation of organic molecules in homogeneous aqueous solution catalyzed by hybrid biocatalysts (based on the Trojan Horse strategy)

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 H 2O 2. The Mn(III)–porphyrin–estradiol-antibody complexes were found to catalyze the oxidation of styrene by KHSO 5, 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.

Effective immobilization of Candida antarctica lipase B in organic-modified clays: Application for the epoxidation of terpenes

The use of three smectite nanoclays (Laponite, SWy-2 and Kunipia) organic-modified with octadecyl-trimethyl-ammonium surfactant, as suitable host matrices for the immobilization of lipase B from Candida antarctica (CaLB) was demonstrated. The resulting hybrid biocatalysts were characterized by a combination of powder X-ray diffraction, thermogravimetric analysis, differential thermal analysis, scanning electron microscopy and infrared spectroscopy. The experimental results confirmed the remarkable binding capacity of the three organoclays for CaLB . Activity and operational stability of immobilized CaLB were determined for the chemo-enzymatic epoxidation of terpenes ( α-pinene and d-limonene) in organic media using various oxidizing agents. The immobilized enzyme retains a significant part of its activity after repeated use under drastic reaction conditions originating from the use of oxidants.

Smectite Clays as Solid Supports for Immobilization of β-Glucosidase: Synthesis, Characterization, and Biochemical Properties

Nanomaterials as solid supports can improve the efficiency of immobilized enzymes by reducing diffusional limitation as well as by increasing the surface area per mass unit and therefore improving enzyme loading. In this work, beta-glucosidase from almonds was immobilized on two smectite nanoclays. The resulting hybrid biocatalysts were characterized by a combination of powder X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric. analysis, differential thermal analysis, and infrared spectroscopy. Biochemical studies showed an improved thermostability of the immobilized enzyme as well as enhanced performance at higher temperatures and in a wider pH range.