A novel peroxidase from Ziziphus jujuba fruit: purification, thermodynamics and biochemical characterization properties

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 H(2)O(2), respectively. It was completely inactivated when incubated with β-mercaptoethanol for 15 min. Hg(2+), Zn(2+), Cd(2+), and NaN3 (5 mM) were effective peroxidase inhibitors, whereas Cu(2+) and Ca(2+) enhanced the peroxidase activity. The activation energy (Ea) for substrate hydrolysis was 43.89 kJ mol(−1), while the Z value and temperature quotient (Q(10)) 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.