Table 3.

In vitro assay of MerA-like activity^a

^aThe activity of the Synechocystis MerA-like enzyme was measured as the consumption of NADPH (nmol · min⁻¹ · mg⁻¹ of protein) that reduces mercuric or uranyl ions. As indicated, MerA was either reduced or glutathionylated and subsequently treated or not treated with Grx1 or Grx2 before the reactions were started. The nature and position of amino acid substitutions in MerA and Grx1 are shown as subscripts. The numbers are the mean values ± standard deviations from four assays (two measurements performed on two independent enzyme preparations). The negative-control experiments performed in the absence of either NADPH, MerA, or mercuric or uranyl ions yielded only background values (1 to 3 units).