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Peroxidase from turnip roots (TP) was isolated followed by modification with methoxypolyethylene glycol (MPEG). The catalytic activity of the modified TP (MTP) on ABTS increased 2.5 times after 80 min of reaction. MTP showed a KM similar value to that of TP, but a significantly greater kcat for ABTS oxidation, in aqueous buffer. Chemical modification produced an enhanced stability in organic solvents and increased thermal stability of about 4 times that of TP, in aqueous buffer at 70 degrees C. Circular dichroism showed that MPEG modification decreased TP alpha-helical structure from 26 to 16% and increased beta-turns from 26 to 34%, resulting in an enhanced conformational stability. The temperature at the midpoint of thermal denaturation (melting temperature) increased from 57 to 63 degrees C after modification. MTP was immobilized in alginate beads (IMTP) and tested for oxidative polymerization of concentrated phenolic synthetic solutions, achieving 17 effective contact cycles removing >65% phenols. IMTP may be useful for the development of an enzymatic process for wastewater effluent treatment.

Background Monoamine oxidase (MAO) is an enzyme that has been targeted pharmacologically for the treatment of depression and neurodegenerative diseases such as Parkinson's disease. To avoid side effects, drugs currently in use must selectively target either of the enzyme's two isoforms, A or B. In this study, we designed molecules derived from chalcone as potential reversible and selective inhibitors of isoform A of the MAO enzyme. Results Ten thousand one hundred compounds were designed and screened using molecular docking, considering the pharmacokinetic processes of chemical absorption, distribution, metabolism, and excretion. Density functional theory calculations were performed for the main ligands to evaluate their reactivity. Six drugs qualified as reversible and irreversible inhibitors of both isoform A and isoform B. Among these, molecule 356 was found to be a reversible inhibitor with the best performance in selectively targeting isoform A of the MAO enzyme. The interaction stability of ligand 356 in the isoform A binding site was confirmed by molecular dynamics. One hydrogen bond was found between the ligand and the cofactor, and up to six hydrogen bonds were formed between the ligand and the protein. Conclusions We selected a drug model (molecule 356) for its high affinity to isoform A over isoform B of the MAO enzyme. This proposal should decrease experimental costs in drug testing for neurodegenerative diseases. Therefore, our silico design of a reversible inhibitor of isoform A of enzyme monoamine oxidase can be used in further experimental designs of novel drugs with minimal side effects. Graphical Abstract