Phosphotriesterase-Magnetic Nanoparticle Bioconjugates with Improved Enzyme Activity in a Biocatalytic Membrane Reactor

Chemical Modification for the "off-/on" Regulation of Enzyme Activity

Enzymes with excellent catalytic performance play important roles in living organisms. Advances in strategies for enzyme chemical modification have enabled powerful strategies for exploring and manipulating enzyme functions and activities. Based on the development of chemical enzyme modifications, incorporating external stimuli-responsive features-for example, responsivity to light, voltage, magnetic force, pH, temperature, redox activity, and small molecules-into a target enzyme to turn "on" and "off" its activity has attracted much attention. The ability to precisely control enzyme activity using different approaches would greatly expand the chemical biology toolbox for clarification and detection of signal transduction and in vivo enzyme function and significantly promote enzyme-based disease therapy. This review summarizes the methods available for chemical enzyme modification mainly for the off-/on control of enzyme activity and particularly highlights the recent progress regarding the applications of this strategy. This article is protected by copyright. All rights reserved.

A 3D printable adapter for solid-state fluorescence measurements: the case of an immobilized enzymatic bioreceptor for organophosphate pesticides detection

The widespread use of pesticides in the last decades and their accumulation into the environment gave rise to major environmental and human health concerns. To address this topic, the scientific community pointed out the need to develop methodologies to detect and measure the presence of pesticides in different matrices. Biosensors have been recently explored as fast, easy, and sensitive methods for direct organophosphate pesticides monitoring. Thus, the present work aimed at designing and testing a 3D printed adapter useful on different equipment, and a membrane support to immobilize the esterase-2 from Alicyclobacillus acidocaldarius (EST2) bioreceptor. The latter is labelled with the IAEDANS, a bright fluorescent probe. EST2 was selected since it shows a high specificity toward paraoxon. Our results showed good stability and replicability, with an increasing linear fluorescent intensity recorded from 15 to 150 pmol of labelled EST2. Linearity of data was also observed when using the immobilized labelled EST2 to detect increasing amounts of paraoxon, with a limit of detection (LOD) of 0.09 pmol. This LOD value reveals the high sensitivity of our membrane support when mounted on the 3D adapter, comparable to modern methods using robotic workstations. Notably, the use of an independent support significantly simplified the manipulation of the membrane during experimental procedures and enabled it to match the specificities of different systems. In sum, this work emphasizes the advantages of using 3D printed accessories adapted to respond to the newest research needs.

Biocatalytic membranes for combating the challenges of membrane fouling and micropollutants in water purification: A review

Over the last few years, the list of water contaminants has grown tremendously due to many anthropogenic activities. Various conventional technologies are available for water and wastewater treatment. However, micropollutants of emerging concern (MEC) are posing a great threat due to their activity at trace concentration and poor removal efficiency by the conventional treatment processes. Advanced technology like membrane technology can remove MEC to some extent. However, issues like the different chemical properties of MEC, selectivity, and fouling of membranes can affect the removal efficiency. Moreover, the concentrate from the membrane filtration may need further treatment. Enzymatic degradation of pollutants and foulants is one of the green approaches for removing various contaminants from the water as well as mitigating membrane fouling. Biocatalytic membranes (BCMs), in which enzymes are immobilized on membranes, combines the advantages of membrane separation and enzymatic degradation. This review article discussed various commonly used enzymes in BCMs for removing MEC and fouling. The majorly used enzymes were oxidoreductases and hydrolases for removing MEC, antifouling, and self-cleaning ability. The various BCM synthesis processes based on entrapment, crosslinking, and binding have been summarized, along with the effects of the addition of the nanoparticles on the performances of the BCMs. The scale-up, commercial viability, challenges, and future direction for improving BCMs have been discussed and shown bright possibilities for these new generation membranes.

A Rationally Designed Supercharged Protein-Enzyme Chimera Self-Assembles In Situ to Yield Bifunctional Composite Textiles

Catalytically active materials for the enhancement of personalized protective equipment (PPE) could be advantageous to help alleviate threats posed by neurotoxic organophosphorus compounds (OPs). Accordingly, a chimeric protein comprised of a supercharged green fluorescent protein (scGFP) and phosphotriesterase from Agrobacterium radiobacter (arPTE) was designed to drive the polymer surfactant (S^-)-mediated self-assembly of microclusters to produce robust, enzymatically active materials. The chimera scGFP-arPTE was structurally characterized via circular dichroism spectroscopy and synchrotron radiation small-angle X-ray scattering, and its biophysical properties were determined. Significantly, the chimera exhibited greater thermal stability than the native constituent proteins, as well as a higher catalytic turnover number (k_cat). Furthermore, scGFP-arPTE was electrostatically complexed with monomeric S^-, driving self-assembly into [scGFP-arPTE][S^-] nanoclusters, which could be dehydrated and cross-linked to yield enzymatically active [scGFP-arPTE][S^-] porous films with a high-order structure. Moreover, these clusters could self-assemble within cotton fibers to generate active composite textiles without the need for the pretreatment of the fabrics. Significantly, the resulting materials maintained the biophysical activities of both constituent proteins and displayed recyclable and persistent activity against the nerve agent simulant paraoxon.

Trends in the development of innovative nanobiocatalysts and their application in biocatalytic transformations

The ever-growing demand for cost-effective and innocuous biocatalytic transformations has prompted the rational design and development of robust biocatalytic tools. Enzyme immobilization technology lies in the formation of cooperative interactions between the tailored surface of the support and the enzyme of choice, which result in the fabrication of tremendous biocatalytic tools with desirable properties, complying with the current demands even on an industrial level. Different nanoscale materials (organic, inorganic, and green) have attracted great attention as immobilization matrices for single or multi-enzymatic systems. Aiming to unveil the potentialities of nanobiocatalytic systems, we present distinct immobilization strategies and give a thorough insight into the effect of nanosupports specific properties on the biocatalysts' structure and catalytic performance. We also highlight the development of nanobiocatalysts for their incorporation in cascade enzymatic processes and various types of batch and continuous-flow reactor systems. Remarkable emphasis is given on the application of such nanobiocatalytic tools in several biocatalytic transformations including bioremediation processes, biofuel production, and synthesis of bioactive compounds and fine chemicals for the food and pharmaceutical industry.

Biocatalytic membrane reactor development for organophosphates degradation

Organophosphates (OPs) are highly toxic compounds used as pesticides and nerve agents. The devastating effects, reported in different studies, on the environment and human health indicate a serious scenario for both instantaneous and long terms effects. Bio-based strategies for OPs degradation seem the most promising solutions, particularly when extremophiles enzymes are used. These systems permit OPs degradation with high efficiency and specificity under mild conditions. However, as frequently observed, enzymes can easily lose activity in batch systems, so that a strategy to improve biocatalyst stability is highly needed, in order to develop continuous systems. In this work, for the first time, a continuous biocatalytic system for organophosphates (OPs) detoxification has been proposed by using a triple mutant of the thermostable phosphotriesterase (named SsoPox) isolated from the hyperthermophilic archaeon Sulfolobus solfataricus. The enzyme was covalently immobilized on polymeric membranes to develop a biocatalytic membrane reactor (BMR) able to hydrolyse a pesticide (paraoxon) contained in water. High paraoxon degradation (about 90%) and long term stability (1 year) were obtained when the enzyme was covalently immobilized on hydrophilic membranes. On the contrary, the enzyme in batch system completely loses its activity within few months after its solubilisation in buffer.