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

Peroxidase POX1 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 POX1A and POX1B. POX1B seems to be more attractive for biosensor design since its Km (app) for H2O2 is lower than that of POX1A. In addition to its storage and operational stability, POX1B was found to be highly heat‐stable, since almost 70% of its activity was conserved at 60 °C, whereas full activity was retained at 50 and 40 °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. POX1B‐based electrodes show great potential for application in H2O2 monitoring of biological samples.