Protein Film Voltammetry of Heme Oxygenase

Heme Oxygenase (HO), a heme-degrading enzyme, is responsible for many physiological functions including heme catabolism, O2 sensing, cellular signaling, iron homeostasis, and antioxidant defense. In vivo, HO is responsible for the catabolism of heme to free iron, CO, and biliverdin. The conversion of heme by HO proceeds through three successive oxygenation reactions forming α-meso-hydroxyheme, verdoheme and biliverdin using seven electrons donated through NADPH-cytochromeP450 reductase. HO enzyme was isolated and reconstituted with Fe(III)-Protoporphyrin. Purity and activity of the enzyme was tested using SDS-PAGE gel and UV-Vis Spectroscopy. Protein Film Voltammetry was carried out under anaerobic and aerobic conditions using basal and edge plane pyrolytic graphite (PG) electrode with films containing Nafion and HO. Under anaerobic conditions, a reduction peak is observed indicating redox activity of the Fe-metal in the heme. Under aerobic conditions a reduction peak is observed suggesting a possible turnover of the enzyme.