COMPARATIVE-STUDY OF THE INACTIVATION OF HORSERADISH-PEROXIDASE UNDER THE EFFECT OF H2O2 AND IONIZING-RADIATION

The inactivation of native and recombinant horseradish peroxidase in the presence of hydrogen peroxide and under ionizing radiation was studied. The types of peroxidase activity differ in sensitivity towards the inactivating effect of H2O2: the activity in relation to the iodide ion is more stable than the activity in relation to ammonium 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and o-phenylenediamine. Similar inactivation was observed in the course of the radiolysis of peroxidase. It was assumed that the initial period of peroxidase inactivation in the presence of hydrogen peroxide has a radical nature and is related to the generation of superoxide radicals, which modify the protein moiety, resulting in the destruction of heme. The R-670 compound was not formed under the conditions studied. However, the E --> EI transition occurred, depending on the radiation dose and the enzyme concentration.