Cassava Root Cortex Peroxidase (CCP) as a Potential Alternative Source of Peroxidase

Abstract

Cassava is one of the most important starch crops in the world. Cassava starch factories normally generate a huge amount of cassava tuberous root residual which is usually discarded and might cause pollution to the environment. In order to find some extra benefits of such waste, in this study, cassava root cortex peroxidase (CCP) was found up to 20 mg/kg fresh deteriorated cortex tissue from tuberous root and also able to demonstrate some applications similar to horseradish peroxidase (HRP). The characterization revealed that major native CCP was a 105-kDa dimeric peroxidase with two 54-kDa monomers. Using 3,3′-diaminobenzidine (DAB) as substrate in the assay, CCP was found to be tolerant and could maintain its activity in a wide temperature range from 20 to 70°C with an optimum at 65°C. CCP was stable in board pH range from 3 to 11 with maximum activity at pH 5.0. Despite simple purification with ammonium sulfate precipitation, partial purified CCP was capable of determining glucose concentrations with glucose oxidase as similar capability as horseradish peroxidase (HRP). For application as reporter enzyme in immunoassays, the self-made secondary antibody conjugated with CCP did successfully detect the protein antigen in Western blot analysis using the luminol as chemiluminescent substrate. These demonstrations indicated CCP as one of the most robust peroxidases. Moreover, the active enzyme could be easily retrieved from the industrial waste of cassava peel at low cost. Further studies should involve optimization of enzyme purification in industrial scale and finding more CCP potential applications which should increase the advantages of this promising enzyme.