Inactivation and Heme Degradation of Horseradish Peroxidase Induced by Discharge Plasma

The effects of non-thermal plasma at the argon gas-solution interface on horseradish peroxidase (HRP), a classical heme-containing protein, were assessed quantitatively. Evidence from spectroscopic approaches showed that enzymatic activity together with the contents of heme and iron in HRP decreased dramatically and concomitantly upon plasma treatment. The plasma induced both long- and short-lived reactive species which inactivated HRP in the solution. In particular, hydrogen peroxide broke the heme prosthetic group into fluorescent products, mainly dipyrrols and their derivatives, while other factors such as hydroxyl radicals and UV radiation generated during radicals and UV radiation generated during plasma discharge accelerated this heme protein degradation process.