Fluorometric determination of the activity of inorganic pyrophosphatase and its inhibitors by exploiting the peroxidase mimicking properties of a two-dimensional metal organic framework.

Abstract

A copper(II)-based two-dimensional metal-organic framework with nanosheet structure (CuBDC NS) that possesses peroxidase (POx) mimicking activity was prepared. In the presence of hydrogen peroxide, the system catalyses the oxidation of terephthalic acid to a blue-fluorescent product (excitation = 315nm; emission = 425nm). Pyrophosphate has a very strong affinity for Cu2+ ionand blocks the POx-mimicking activity of theCuBDC NS. If, however, inorganic pyrophosphatase is present, the POx mimicking activity is gradually restored because pyrophosphate is hydrolyzed. The findings were used to design a method for the determination of the activity of inorganic pyrophosphataseby fluorometry. Fluorescence increases linearly in the 1-50mU·mL-1inorganic pyrophosphatase activity range. The limit of detection is 0.6mU·mL-1 (S/N= 3). Graphical abstract A copper(II)-based two-dimensional metal-organic framework (CuBDC NS) is described that possesses POx-mimicking activity. Inorganic pyrophosphate (PPi) was hydrolyzed to phosphate in the presence of inorganic pyrophosphatase (PPase). Hence, it cannot coordinate with Cu2+ in CuBDC NS, its structure was well-conserved to catalyses the oxidation of terephthalic acid (H2BDC) to produce a blue fluorescent product (oxBDC) in the presence of hydrogen peroxide (H2O2).