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Hydrolytic Enzymes for the Synthesis of Pharmaceuticals
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Sergio González-Granda, Vicente Gotor-Fernández
Other amidases have also been elegantly employed in the hydrolysis of amides for the synthesis of the corresponding carboxylic acids. This is the case of the desymmetrisation of 2-ethyl-2-methylmalonamide using different biocatalysts (Nojiri et al., 2015), including 21 microorganisms and 2 amidases (CsAM from Cupriavidus sp. KNK-J915 and CnAM from Cupriavidus necator JM P134). The CsAM-catalysed hydrolysis of the target prochiral diamide was successfully achieved on an 80 g-scale, so the (S)-amido acid was obtained as crude product in full conversion and >98% ee after 22 h at 32°C (Scheme 9.15). The so-obtained amide served as ideal precursor of (R)-isovaline through a chemical Hofmann rearrangement, compounds that has been reported to activate the metabotropic γ-aminobutyric acid-B receptor, acting for instance as an analgesic agent. Amidase-catalysed desymmetrisation of 2-ethyl-2-methyl-malonamide for the chemoenzymatic synthesis of (R)-isovaline.
Silver as an Antimicrobial Agent: The Resistance Issue
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
Kristel Mijnendonckx, Rob Van Houdt
Notably, hormesis has been observed when E. coli K-12 and Cupriavidus necator H16 were exposed to sublethal concentrations of Ag NPs (Schacht et al. 2013; Xiu et al. 2012). This stimulatory effect could be elicited by the residual Ag+ in the Ag NPs stock suspension (Xiu et al. 2012) and is of significant importance to consider in antimicrobial applications of Ag NPs.
Nanotoxicity of engineered nanomaterials (ENMs) to environmentally relevant beneficial soil bacteria – a critical review
Published in Nanotoxicology, 2019
Ricky W. Lewis, Paul M. Bertsch, David H. McNear
Zinc-containing ENMs represent a large portion of nanomaterials expected to be enriched in biosolids-amended soils at an exponential rate (Gottschalk et al. 2009; Barton et al. 2015; Garner et al. 2017). Several nanotoxicological studies have examined the effects of ZnO ENMs on PGPR and related species (Table S2). In the soil bacterium, Cupriavidus necator JMP134, 1–3 nm acetate-stabilized ZnO ENMs elicited differential global protein expression profiles compared with Zn2+ supplied as zinc acetate (Zn-OAc) (Neal et al. 2012). While it remains unclear what nanoscale properties may play a role in the observed responses, ZnO ENMs elicited expression of membrane proteins not expressed with Zn2+ exposure. Unfortunately, the proteomic responses of bacteria to ZnO ENMs and nanoparticles generally remain unexplored, so there is little with which to compare these results. Nevertheless, this study demonstrated the power of examining proteomic responses to tease out differences between ENM and ion-driven toxic responses.
Mechanistic study of copper oxide, zinc oxide, cadmium oxide, and silver nanoparticles-mediated toxicity on the probiotic Lactobacillus reuteri
Published in Drug and Chemical Toxicology, 2023
Aya M. Eid, Osama M. Sayed, Walaa Hozayen, Tarek Dishisha
The toxic effect of NPs was clearly apparent by analysis of bacterial growth, as the bacteria could not reach their maximum specific growth rates compared to control, even at concentrations below the MICs. CuO-, ZnO- and Ag-NPs were reported earlier to have a significant inhibitory effect on the growth of S. aureus, Cupriavidus necator, and Pseudomonas aeruginosa (Schacht et al.2013, Navale et al.2015, Alavi et al.2019). In addition, the effect of CdONPs through growth suppression has been reported in bacteria (Asghar et al.2020) and other organisms (Samar El Kholy 2020).