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. 2015 Apr 27;10(4):e0125701. doi: 10.1371/journal.pone.0125701

Fig 3. Comparison of minimal required enzyme concentrations among different detection systems.

Fig 3

The lowest concentration of the enzyme required for detection was determined for four different enzyme-substrate systems: (A) TurboNuclease and FLOS system; (B) alkaline phosphatase (ALP) and p-nitrophenylphosphate (pNPP) system; (C) horseradish peroxidase (HRP) and o-Phenylenediamine (OPD) system; and (D) ALP and 4-methylumbelliferyl phosphate (4-MUP, a classical fluorogenic substrate) system. Each enzyme was prepared at 1:10 serial dilutions (starting at 10–7 M) and reacted with its corresponding substrate. Negative control (NC) contained all components except the enzyme. The cutoff (2.1 fold higher than the NC signal) is indicated by the dotted line. Means ± SD are shown.