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A novel plant peroxidase was isolated from the stem of Arabian balsam (Commiphora gileadensis) and purified using ammonium sulfate, followed by ion exchange chromatography (DEAE-Sepharose) and gel filtration (Sephcryl S-200). The newly isolated peroxidase was characterized as having a specific activity of 9503.3 unit/mg of protein after 20.3-fold purification, which yielded a recovery of 18.5%. Based on the subunit size, the purified peroxidase was a 40 kDa monomeric structure and presented high thermostability, as it was entirely stable at 55 °C for 30 min and retained approximately 13.6% of its activity at 85 °C. The optimal pH exhibited a broad value range (pH 7.0- 7.5). The kinetic parameters for the purified peroxidase were obtained. To increase the enzyme durability, efficiency and reusability, the peroxidase was entrapped onto a carboxymethyl cellulose/Fe 3 O 4 magnetic hybrid material. The immobilized enzyme was characterized by scanning electron microscopy (SEM) and FT-IR spectroscopy. It was tested at different pH values, storage times and temperatures, and its kinetic behavior was assessed. The immobilized enzyme maintained its activity upon storage at 4 and 25 °C for 8 weeks, and upon recycling for up to 15 uses. Arabian balsam peroxidase appears to be candidate for industrial applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this study, peroxidase from Ziziphus jujuba was purified using ion exchange, and gel filtration chromatography resulting in an 18.9-fold enhancement of activity with a recovery of 20%. The molecular weight of Z. jujuba peroxidase was 56 kDa, as estimated by Sephacryl S-200. The purity was evaluated by SDS, which showed a single prominent band. The optimal activity of the peroxidase was achieved at pH 7.5 and 50 °C. Z. jujuba peroxidase showed catalytic efficiency (Kcat/Km) values of 25 and 43 for guaiacol and H2O2, respectively. It was completely inactivated when incubated with β-mercaptoethanol for 15 min. Hg2+, Zn2+, Cd2+, and NaN3 (5 mM) were effective peroxidase inhibitors, whereas Cu2+ and Ca2+ enhanced the peroxidase activity. The activation energy (Ea) for substrate hydrolysis was 43.89 kJ mol−1, while the Z value and temperature quotient (Q10) were found to be 17.3 °C and 2, respectively. The half-life of the peroxidase was between 117.46 and 14.15 min. For denaturation of the peroxidase, the activation energy for irreversible inactivation Ea*(d) was 120.9 kJmol−1. Thermodynamic experiments suggested a non-spontaneous (∆G*d > 0) and endothermic reaction phase. Other thermodynamic parameters of the irreversible inactivation of the purified enzyme, such as ∆H* and ∆S*, were also studied. Based on these results, the purified peroxidase has a potential role in some industrial applications. [ABSTRACT FROM AUTHOR]

The online version of the original article can be found at https://doi.org/10.1007/s10562-022-04185-y. B Correction to: Catalysis Letters (2022) b https://doi.org/10.1007/s10562-022-04185-y The original version of this article unfortunately contained an error in the affiliation of the author Dr. Muhammad Bilal. [Extracted from the article]

In the present study, nanodiamond (ND) was blended with polymethyl methacrylate (PMMA) and then electrospun into nanofibers (nfPMMA-ND) for the immobilization of horseradish peroxidase (HRP). The maximum immobilization efficiency of HRP (96%) was detected at 10% ND and pH 7.0. ATR-FTIR, SEM and TEM were used to characterize the immobilized enzyme. The immobilized enzyme retained 60% of its initial activity after ten reuses. The pH was shifted from 7.0 for soluble HRP to 7.5 for the immobilized enzyme. The soluble HRP had an optimum temperature of 30 °C, whereas this temperature was shifted to 40 °C for the immobilized enzyme. The substrate analogs were oxidized by immobilized HRP with higher efficiencies than those of soluble HRP. The kinetic results showed that the soluble HRP had more affinity toward guiacol and H2O2 than immobilized HRP. The effect of metal ions on soluble and immobilized HRP was studied. The immobilized HRP was markedly more stable when it exposed to urea, isopropanol, butanol and heptane compared with the soluble enzyme. The immobilized HRP exhibited high resistance to proteolysis by trypsin than that of soluble enzyme. In conclusion, the nfPMMA-ND-HRP could be employed in several applications such as biosensor, biomedical and bioremediation. [ABSTRACT FROM AUTHOR]

In this work, we propose a facile technique to dually-immobilize α-amylase and horseradish peroxidase (HRP) as two different enzyme models via entrapment within two distinct polymeric electrospun fibers by simple mixing steps and compare their properties with both individually immobilized forms and with the free counterparts. The immobilization was verified using Fourier transform infrared spectroscopy (FTIR) and Field emission scanning electron microscope (FESEM). The immobilization efficiencies for the dual-immobilized HRP and α-amylase were 89% and 85%, respectively. The retained catalytic activities of the dual-immobilized HRP and α-amylase enzymes were observed to be 79% and 80.2% after 10 cycles, respectively. After storage for 12 weeks, the dual-immobilized enzymes still retained nearly 90% activities similar to the individually immobilized ones. This immobilization procedure did not appear to exert either negative or back inhibitory effects upon both enzymes with respect to the different enzymatic assay procedures. This approach demonstrates that two or more type of enzymes could be mixed with different polymers individually and undergoes electrospinning simultaneously. We believe that this approach is expected to considerably promote and extend the application of multi-enzyme systems and worth further investigation for potential enzyme mediated cascade reactions. Unlabelled Image • Two distinct polymeric electrospun fibers were fabricated by dual immobilization of HRP and α-amylase. • The two immobilized enzymes had enhanced pH and storage stability. • The two immobilized enzymes had enhanced kinetics parameters. • The two immobilized enzymes retained 80% of the initial activity after 10 cycles. [ABSTRACT FROM AUTHOR]