A Comparison of Spectrophotometric and Oxidoreduction Potential Method for Laccase Activity Measurement

Abstract

Res Med Eng Sci is reduced back to catechu [12]. A year later the same group using a polarized rotating platinum electrode enabled PPO activity measurement at various ascorbic acid concentrations continuously recording oxygen consumption [13]. Furthermore, the oxygen-uptake curves were non-linear with time. A photometric method (λ617 nm, ε = 11,080 M -1 cm -1 in dichloromethane) has been proposed to measure PPO activity in olives in the presence of 4-amino-N, N-diethyl Aniline Sulphate (ADA) -excellent substrate for lactase and PPOs [14]. The same principle enabled the rapid detection of catecholase activity of PPO on slab gels based on 4-tert butyl catechu oxidation to yellow o-quinine, which in turn quickly reacts with the coupling agent ADA leading to a deep blue adduct [15]. Other methods such as optical and amperometric biosensors and visible near-infrared hyper spectral imaging have also been used to predict PPO activity in a non-destructive manner [16]. Recently measured polyphenol oxidise activity using optical waveguide light mode spectroscopy-based immunosensor. The sensor was suitable for detecting very low PPO activity that might be present in some food samples for which a conventional colorimetric assay may not be applicable. Previously, we investigated ferulic acid oxidation by Myceliophthorathermophila lactase to synthesize 'nature identical' stable pigments that could be used in cosmetics and foods [10]. In aqueous medium, the rate of ferulic acid conversion (0-60min) decreased from 5-0.5mm with negligible yield of yellow colour products, due to the higher activity of both enzyme and semi-quinine radical [10]. Recently, a purified Myceliophthorathermophila lactase was used as a biocatalyst to enzymatic ally oxidize ferulic acid in aqueous medium using an eco-friendly procedure to synthesize new active molecules [17]. Diametric species of ferulic acid (molecular mass 386g/mol) were found after complete ferulic acid oxidation (150min) by the purified Myceliophthorathermophila lactase [17]. In this investigation, we studied ferulic acid and catechu oxidation by Myceliophthorathermophila lactase using oxide reduction potential as a novel method to determine PPO activity compared to the traditional spectrophoto metric method.