A new peroxidase from garlic (Allium sativum) bulb: its use in H2O2 biosensing

摘要

Peroxidase POXI isoenzyme was purified from garlic (Allium sativum L.) bulb by ammonium sulfate precipitation, gel filtration and anion-exchange chromatography. Native-PAGE profile showed two isoforms, designated POXIA and POXIB. POXIB seems to be more attractive for biosensor design since its K-m (app) for H2O2 is lower than that of POXIA. In addition to its storage and operational stability, POXIB was found to be highly heat-stable, since almost 70 of its activity was conserved at 60 degrees C, whereas full activity was retained at 50 and 40 degrees C for 40 min. The optimal pH was approx. 5 and the optimal temperature was 30 C. Next, gelatin was used as a matrix for enzyme immobilization on a gold electrode surface and electrochemical measurements were performed by using cyclic voltammetry. POXIB-based electrodes show great potential for application in H2O2 monitoring of biological samples.