Abstract
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 56kDa, 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 degrees 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 beta -mercaptoethanol for 15min. Hg2+, Zn2+, Cd2+, and NaN3 (5mM) were effective peroxidase inhibitors, whereas Cu2+ and Ca2+ enhanced the peroxidase activity. The activation energy (Ea) for substrate hydrolysis was 43.89kJmol(-1), while the Z value and temperature quotient (Q(10)) were found to be 17.3 degrees C and 2, respectively. The half-life of the peroxidase was between 117.46 and 14.15min. 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.