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Hydrolytic Enzymes for the Synthesis of Pharmaceuticals
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Sergio González-Granda, Vicente Gotor-Fernández
Biocatalysis has acquired maturity in the twenty-first century since enzyme catalysis preserves the 12 principles of green chemistry (Anastas et al., 1994), allowing the efficient production of agrochemicals, functionalised material, pharmaceuticals and high-added value products. Both the academic and the industrial sector have implemented this technology for practical purposes, which nowadays can be considered as an additional tool for most of the organic chemists (Patel, 2007; Hudlicky and Reed, 2009; Clouthier and Pelletier, 2012; Solano et al., 2012; Bezborodov and Zagustina, 2016; Patel, 2016; Alcántara and Alcántara, 2018). In addition, the advances in enzyme immobilisation techniques (García-Galan et al., 2011; Barbosa et al., 2015), possibility to create evolved enzymes by modification of their amino acid sequence (Porter et al., 2016; Wang et al., 2017), design of novel enzyme through chemical modifications (Filice and Palomo, 2015), and rationalisation of the experimental results by means of computational calculations (Romero-Rivera et al., 2017) made biotransformations adequate solutions for challenging synthetic targets.
Biocatalytic Nanoreactors for Medical Purposes
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Oscar González-Davis, Chauhan Kanchan, Rafael Vazquez-Duhalt
The premise of using biomaterial-based nanoparticles for enzyme immobilization and delivery is that they intrinsically possess high reactivity due to their small size and large specific surface area, which tend to facilitate the exposure of active sites for triggering catalytic reactions. Additionally, they can be easily modified with functional groups to covalently bond enzymes, they reduce diffusion limitations while increasing stability and targeting capabilities, they protect them from proteolysis, and most importantly they are compatible with cellular components (Koyani et al., 2017). Moreover, the NC modification with “stealth” moieties, such as PEG, can reduce the immune response and further prevent enzyme degradation increasing their circulation in the bloodstream (Lin et al., 2018; Xie et al., 2009; Zhao et al., 2011). Few examples of nanobioreactors for enzyme delivery are highlighted in Fig. 18.1.
Flexible and Wearable Chemical Sensors for Noninvasive Biomonitoring
Published in Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami, Healthcare Sensor Networks, 2016
Hiroyuki Kudo, Kohji Mitsubayashi
The most promising method for continuous glucose monitoring has been enzyme-based biosensors. The glucose biosensor uses the enzyme glucose oxidase (GOD), which is responsible for catalyzing the conversion of β-D-glucose and oxygen to D-glucono-1,5-lactone and hydrogen peroxide. Glucose is usually measured by quantifying the production of hydrogen peroxide or the consumption of oxygen by the GOD reaction using electrochemical or spectrophotometric methods. A flexible glucose sensor can therefore be designed by immobilizing GOD at the sensing region of the flexible oxygen sensor. Figure 6.9 illustrates the enzyme-immobilization method used to construct a flexible glucose sensor. GOD was immobilized on the surface of a flexible oxygen sensor that had been treated with an aminopropylsilane monolayer. A mixture of phosphate buffer containing GOD and water-soluble photosensitive resin (AWP: Azide-unit pendant Water-soluble Photopolymer, Toyo Gosei Kogyo Co., Ltd., Japan) was then cured by illuminating it with ultraviolet light.
Recent advances in electrochemical and optical sensing of the organophosphate chlorpyrifos: a review
Published in Critical Reviews in Toxicology, 2022
Athira Sradha S, Louis George, Keerthana P, Anitha Varghese
Enzyme-immobilization is one of the most commonly explored techniques. While they offer good sensitivity, they lack in terms of specificity and stability under extreme conditions. Use of nanozymes in this regard offers a potential solution. Nanomaterials are extensively used in many sensors to increase surface area, rate of electron transfer, etc. However, biocompatibility is still an area that needs to be explored more carefully. There are several nontoxic materials that become toxic at nano-levels. MIP sensors with stable synthetic receptors could override the disadvantages of enzyme-based sensors however difficulties regarding electropolymerization need to be overcome. Electrochemical methods are sensitive to temperature, pH and require a constant power source. Though optical techniques like SERS, surface plasmon resonance, etc., are promising, they are quite expensive and require skilled personnel. Much emphasis is required on portable, commercially viable and easy-to-use sensors. Reusability, real sample analysis, cost, shelf-life of sensors are some of the factors that encourage commercialization of sensors and hence special attention must be laid upon these properties. Sensors using smart technologies like smart-phone based detection can make pesticide detection techniques more appealing. Considering the revolutionary developments in the past, it is not hard to imagine the disappearance of such challenges and drawbacks in the immediate future. With the contributions from the scientific community pouring in rapidly, the future prospects of pesticide sensing look promising.
Advances in biocatalytic and chemoenzymatic synthesis of nucleoside analogues
Published in Expert Opinion on Drug Discovery, 2022
Sebastian C. Cosgrove, Gavin J. Miller
To avoid the optimization of enzyme immobilization and selection of an appropriate support, Wagner et al. demonstrated that catalytically active inclusion bodies (CatIB) could be used as naturally occurring immobilized enzymes [43]. Inclusion bodies are aggregated insoluble proteins that form as a consequence of incorrect folding and protein denaturing. Often these aggregates are disregarded; however, the authors here found that an adenosine 5′-monophosphate phosphorylase from Thermococcus kodakarensis (TkAMPase), which could enable transglycosylation of cytidine 5’-monophosphate (CMP), was primarily eluted in the insoluble fraction after protein purification (>80% of the protein). This precipitate was found to be active and could be used at higher temperatures (up to 90 °C) with retention of activity. The conversions were generally poor (no yield >26% for CMP at 60 °C), and the reactions were only run in the 96-well assay format, so were limited by scale. This does, however, offer a practically free immobilization method, and the resulting heterogenous catalysts are entirely biodegradable.
Immobilization of Trichoderma harzianum α-amylase on PPyAgNp/Fe3O4-nanocomposite: chemical and physical properties
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Saleh A. Mohamed, Majed H. Al-Harbi, Yaaser Q. Almulaiky, Ibrahim H. Ibrahim, Hala A. Salah, Mohamed O. El-Badry, Azza M. Abdel-Aty, Afaf S. Fahmy, Reda M. El-Shishtawy
Since amylase enzyme contains thiol and/or disulfide and amino acid groups among its chemical structure, thus it was hypothesized that having a composition of PPy and AgNp would furnish a good enzyme immobilization matrix by virtue of the positive charges of PPy [23], which help binding with enzyme by ionic bonds and AgNp with its propensity to bind with thiol and/or disulfide groups [25]. Generally, Fe3O4 magnetic nanoparticles have been used in protein/enzyme immobilization [26]. Also the use of magnetite in the composition is beneficial for easy magnetic separation. In the present study, PPyAgNp was mixed with Fe3O4 magnetic nanoparticles to become PPyAgNP/Fe3O4 nanocomposite (Figure 1) in order to immobilize Trichoderma harzianum α-amylase. The immobilization of enzyme on magnetic Fe3O4-nanoparticles combined with different concentrations of PPyAgNP at different pH was carried out. The highest immobilization efficiency (75%) was detected at 10% PPyAgNP and pH 7.0 (Table 1). The loss of the activity of immobilized enzyme by increasing the PPyAgNP concentration could be attributed to the presence of multipoint attachments of the enzyme to the nanocomposite. The rate of the enzyme immobilization depends on the enzyme concentration. Figure 2 shows the rate of immobilization increased with increasing α-amylase concentration. The highest rate of immobilization was detected at 30 unit of enzyme (75% residual activity).