Mercury, enzyme induction

A transient increase of catalase capacity was found after application of a toxic lead concentration to Zea mays seedlings (Hoxha et al., 1985). Evidence was presented for a protective role of catalase after intoxication with heavy metals. De Vos (1991) reported a copper-induced increase of catalase capacity in copper-sensitive Silene cucubalus. In Lemna minor fronds and Allium cepa roots, the same enzyme induction was observed with mercury (Subhadra et al., 1991). 

Furakawa, K. and Tonomura, K., 1972b. Induction of a metallic mercury releasing enzyme in mercury-resistant F scudomonas. Agric. Biol. Chem., 36 2441—2448. 

Mercury toxicity is related to the induction of oxidative stress, as revealed by the decrease in antioxidant enzymes as glutathione S-transferase (Reddy et al. 1981). Examining interactions of purified Mn-superoxide dismutase (1 fM) with HgCl2 indicated that mercury ions suppressed Mn-superoxide dismutase activity by reduction of the native form (Shimojo et al. 2002). Due to the minimal hepatic accumulation of inorganic mercury after the subcutaneous application of HgCl2 (0.25-3 mg/kg) to mice the hepatic Mn-superoxide dismutase might be unaffected while the renal enzyme due to a 34-75 times higher accumulation of mercury in the kidney was decreased in a dose-dependent manner. 

Early in vivo studies examining the effect of metals on HO demonstrated that metal induction of HO is tissue specific with respect to the inducing metal. Most of these studies examined HO induction by assaying enzymatic activity. Cadmium, mercury, lead, chromium, manganese, iron, cobalt, nickel, copper, tin, indium, thallium, platinum, silver, and selenium have been shown to induce HO in liver (Maines and Kappas 1977 Woods et al. 1979, 1984 Eaton et al. 1980) however, cobalt and cadmium are the most effective inducers. In contrast, nickel, tin, and platinum represent the best inducers of the enzyme in kidney in heart, mercury is the most effective. While the usual response of HO to metals is induction of synthesis and... 

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