Figure 3: Effect of Mg2+ on the activity of SeHAS triple Cys-mutants. A. HAS activity was determined as in Figure 2 using membranes containing wildtype SeHAS or the four triple Cys-mutants. The single remaining Cys residue is designated for the indicated triple-Cys-mutants: wildtype, white circle; Δ3C(C226), ■; ; Δ3C(C262), ●; Δ3C(C281), ▲; Δ3C(C367), ▼. B shows the 0 - 1.0 mM region of panel A enlarged.