Screening Inhibitors of Bacterial Membrane-Bound Pyrophosphatase Using a Colorimetric Assay

Bacterial membrane-bound pyrophosphatase, or mPPase, hydrolyzes pyrophosphate into orthophosphate while pumping sodium ions across the membrane.

To assess inhibitor effects against mPPases, add increasing concentrations of phosphate standards to tube strips.

Introduce test compounds, which may inhibit mPPase, into tubes, leaving one with water as the control.

Add liposome-embedded mPPases derived from the thermophilic bacterium Thermotoga maritima to all tubes except the standards.

Seal and incubate at the optimal temperature to activate the enzyme.

Add sodium pyrophosphate to initiate the reaction and release orthophosphate.

Transfer the tubes to a cooling platform to stop the reaction and centrifuge to remove condensation.

Add the molybdate-ascorbate reagent to react with orthophosphate and form phosphomolybdic acid.

Add the arsenite-citrate solution to reduce the acid, forming a stable blue complex.

Transfer the contents to a multiwell plate and measure absorbance.

A lower absorbance compared to the control indicates mPPase inhibition, while the standards serve as a reference for phosphate quantification.

Add one milliliter of solution B to 10 milliliters of solution A, mix by hand, and st