Biochemical Properties of Purified Peroxidase from Rhizome of Turmeric (Curcuma longa L.)

Abstract

We report the bioavailability, purification, and biochemical properties of peroxidase from the rhizome of turmeric (Curcuma longa). The potentials of the purified enzyme in some biotechnological applications were described. Turmeric peroxidase was first purified efficiently using aqueous two-phase partitioning (ATPS) with a percentage yield and purification fold of 51% and 5 respectively. The purified turmeric POD had a subunit molecular mass of 69 ± 0.2 kDa as adjudged on SDS-PAGE and a native molecular mass of 72 ± 0.3 kDa using mass spectrometry (MS) analysis. This suggested that turmeric POD is monomeric in nature. Substrate specificity analysis revealed that catechol was the preferred substrate for the enzyme among other substrates investigated. The order of substrate preference for the purified enzyme was catechol>o-dianisidine>pyrogallol>L-DOPA. The optimum temperature and pH of the purified turmeric POD were 60 ⁰C and 8.0 respectively. The activation energy was estimated to be 3.67 kJ/ mol. The enzyme was stable to temperature retaining up to 70% activity at 60 ^oC after 1 hr. The purified enzyme was activated in the presence of chlorides of Na⁺, K⁺, Ca²⁺, Cu²⁺ and Zn²⁺ however was inhibited by Ba²⁺ and NH₄⁺. Turmeric peroxidase was stable and retained close to 70% in the presence of 30% water immiscible organic solvents such as chloroform, n-hexane and petroleum ether. The combination of biochemical properties of purified turmeric POD would be of interest and applicability in several biotechnological properties.