Chemiluminescence of horseradish peroxidase and acetaldehyde related with gallic acid and hydrogen peroxide interaction

This study focuses on the fact that the chemiluminescence in the visible re gion is emitted from the H2O2/gallic acid/ horseradish peroxidase (HRP) and the H2O2/gallic acid acetaldehyde (MeCHO) systems. The concentration depen dence of chemiluminescence intensity that led to the different response of HRP and MeCHO toward H2O2 indicates that the photon emission participates w ith peroxidase activity including an electron transfer reaction. From our e xperimental results, in this study, we postulated a reaction process for ch emiluminescence based on a one-electron redox shuttle from H2O2 by peroxida se. The photon intensity and spectra data from the H2O2/HRP and the H2O2/Me CHO systems with various catechins were not only affected by HRP and MeCHO but also corresponded with the chemical structure of catechins. The energy calculated from the spectra is 47-64 kcal/mol. These results suggested that the chemiluminescence of both systems arose from excited carbonyl compound s produced by an intermediate of the alkyl radical and the metal-bound hydr oxyl (compound II species). Hydroxyl radical inhibition, showing a notable increase from the gallic acid addition, makes the decay of the hydroxyl for m of heme iron the most likely candidate for the chemiluminescence.