A. Haberland et al., COMPARISON OF MALONDIALDEHYDE AND HYDROGEN-PEROXIDE MODIFIED CUZNSOD BY EPR SPECTROSCOPY, Agents and actions, 40(3-4), 1993, pp. 166-170
CuZn superoxide dismutase (CuZnSOD) contributes to the regulation of t
he steady-state concentration of reactive oxygen species in cells and
minimizes pathological consequences induced by these reactive oxygen s
pecies. During the exaggerated formation of reactive oxygen species, o
ften resulting from an activation of phagocytotic cells, CuZnSOD is ad
ministered with a therapeutic purpose. But inhibition of the endogeneo
us or administered CuZnSOD by products generated during the process of
formation of reactive oxygen species (H2O2, HOCl, .OH, products of li
pid peroxidation) might intensify cell damage. In this study, we compa
red the influence of malondialdehyde (MDA, high reactive molecule form
ed in lipid peroxidation) and H2O2 (known to inhibit the CuZnSOD) on b
ovine CuZnSOD. MDA reacted with CuZnSOD. The reaction was found to be
both time- and concentration-dependent, which was demonstrated by the
formation of fluorophors. EPR spectroscopy revealed that this reaction
had no influence on the activity of CuZnSOD since the catalytic centr
e of the CuZnSOD was not effected by MDA. In contrast, H2O2 modified t
he catalytic centre which caused an activity decrease.