Hg2+-stimulated NADH-oxidase activity of Ascaris muscle microsomal lipoamide dehydrogenase.

In the presence of Hg²⁺$\text{Ascaris}$ lipoamide dehydrogenase stimulated the reduction of oxygen, ferricyanide, and 2,6-dichlorophenolindophenol with NADH, which was inhibited by lipoic acid. On the other hand, Cu²⁺ stimulated the reduction of the artificial dyes, but only a little the reduction of oxygen. Hg²⁺ changed the visible absorption spectrum of the lipoamide dehydrogenase, but did not change the fluorescence curve. Lipoic acid decreased the fluorescence, but did not change the visible absorption spectrum. The $\text{Ascaris}$ lipoamide dehydrogenase have two SH groups per one subunit and 5–6 moles of HgCl₂ and 3–4 moles of CuSO₄ per one subunit were required for the maximal activity.