Proteins/protein binding mercury compounds

The divalent cation exists in both a nondiffusible form (tissues) and a diffusible form (blood) (Halbach and Clarkson 1978 Magos 1967) (see Section 2.3.2). The mechanism for the distribution of mercury and its compounds probably depends on the extent of uptake of the diffusible forms into different tissues or on the mercury-binding to protein-binding sites (sulfhydryl groups) in red cells and plasma proteins (Clarkson 1972b). 

Many bacteria are resistant to inorganic and organic mercury compounds. Mercuric reductase (MerA) is a key enzyme in the mercury detoxification pathway. MerA catalyzes the NADPH-dependent reduction of Hg to its volatile, uncharged, elemental state (Hg ). MerA is a cytosolic protein that is homologous to GR, but also has a short C-terminal extension and a long N-terminal extension not found in GR. MerA contains three pairs of cysteines one in the C-terminal extension, one in the N-terminal extension, and one in the GR-like region of the protein. The N-terminal domain binds one molecule of mercury and delivers it to the catalytic core of the protein, made up of the GR-like portion and the C-terminal extension, where it is reduced. The disulfide from... 

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