Abstract
A novel peroxidase isolated from a local chick pea (Cicer arietinum L.) cultivar (Balksar 2000) was purified by means of ammonium sulfate precipitation, DEAE-cellulose chromatography and two runs on gel filtration. The purified enzyme has a specific activity of 2045 U/mg with 17 % activity recovery. The molecular mass of the enzyme was estimated to be 39 kDa by SDS-polyacrylamide gel electrophoresis. Optimum pH and temperature of the enzyme were 5.5 and 45°C respectively. The thermal denaturation of local chick pea peroxidase was studied in aqueous solution at temperatures ranging from 45°C to 65°C. The temperature of 50% inactivation of the enzyme was found to be 68°C. The enthalpy (ΔH*) and free energy (ΔG*) of thermal denaturation of chick pea peroxidase were 101.4 and 103.4 k J/mol respectively at 65°C.Metals like Zn2+, Mn2+ , Hg2+, Co2+ and Al3+ slightly inhibited the peroxidase activity while Ca2+, Mg2+ and Ba2+ have no effect on enzyme activity. The high specific activity and thermal stability make chick pea peroxidase an alternative to horseradish peroxidase (HRP) in various applications.
Keywords: Chick pea peroxidase, Cicer arietinum L, thermal denaturation, purification, thermostability, free energy