FIG 3. Copper, zinc, and nickel inhibit RclA activity in vitro.

Reactions (500 μl) contained 10 mM HEPES-KOH buffer (pH 7.4), 160 μM NADH, 100 μM HOSCN, and the indicated concentrations of metal salts, and were started by addition of 10 nM RclA. I quantified NADH consumption at A340 for 1 min at 20°C and calculated specific activities as μmol NADH consumed min⁻¹ mg⁻¹ RclA (n=3–4 experimental replicates; error bars of 1 standard deviation). Asterisks indicate activities significantly different from that of RclA with no metals added in a given set of experiments (one-way ANOVA with Dunnett9s multiple comparisons test; ** = P<0.01. *** = P<0.001, **** = P<0.0001). X symbols indicate that RclA precipitated at 100 μM CuCl2.