Construction of a Turn Off-On-Off Fluorescent System Based on Competitive Coordination of Cu²⁺ between 6,7-Dihydroxycoumarin and Pyrophosphate Ion for Sensitive Assay of Pyrophosphatase Activity

Figure 9

(a) Fluorescence responses of Cu²⁺-PPi (Cu²⁺: 200 μM, PPi: 200 μM) complex with DHC (500 μM) after adding different concentration of NaF-treated PPase (0.25 U) in HEPES aqueous buffer (10 mM, pH 6.5). The concentration of NaF (curves A to I: 0, 0.1, 1, 5, 10, 50, 100, 500, and 1000 μM). The final volume of each resulting mixture was adjusted to 500 μL. (b) Fluorescence intensity versus the NaF concentration. Error bars were estimated from three replicate measurements. Other reaction conditions are the same as Figure 1.

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(b)