These experiments indicate strong susceptibility of antioxidant
enzymes in liver to Pb toxicity. It is probably a consequence
of lead binding to —SH groups in protein structures, as well as of
interactions with biometals (Zn, Cu, Mn, Se) in the active center of
enzymes. Moreover, CAT is a heme-containing enzyme and is strongly
affected by Pb, although decrease of this enzyme can be explained
by interactions of Pb and Fe, as well.