Figure 6: Transient downregulation of the catalytic activity of Au NP 1.

(a) Catalysis of the transphosphorylation of HPNPP by Au NP 1. (b) Relative reaction rates (ν/ν₀) as a function of the concentration of either ATP or the mixture AMP+2P_i. Experimental conditions: [TACN·Zn²⁺]=10±1 μM, [HPNPP]=1 mM, [HEPES]=10 mM, pH 7.0, [CaCl₂]=1.0 mM, 37 °C. (c) Absorbance at 400 nm (originating from the reaction product p-nitrophenolate) as a function of time for different mixtures. The red dot indicates the time at which inhibitors were added. The lower slope after reactivation of Au NP 1 at higher concentrations of ATP is caused by the higher concentrations of produced waste (see the inhibition by different concentrations of the waste mixture given in Supplementary Fig. 8). Experimental conditions: [TACN·Zn²⁺]=10±1 μM, [HPNPP]=1 mM, [HEPES]=10 mM, pH 7.0, [CaCl₂]=1.0 mM, [potato apyrase]=0.06 U ml⁻¹, 37 °C. (d) Absorbance at 400 nm as a function of time on the sequential additions of ATP (5 × 3 μM). The red dots indicate the time of addition. Experimental conditions: same as for c.