Figure 2

Phospholipase C enzymatic assay.

This assay is based on the detection of the hydrolysis of p-nitrophenylphosphorylcholine (p-NPPC) to p-nitrophenol. While the substrate, p-NPPC, is colourless, the product p-nitrophenol due to its ability to absorb light at 410 nm, is yellow. About 500 μg of total protein were used in the assay and measurements were performed in triplicates. (A) Crude extracts of 4 day-old cultures from different M. tuberculosis strains were incubated with 5 mmol.l⁻¹ of p-nitrophenol phosphorylcholine; (B) Measurement of phospholipase activity of different M. tuberculosis strains over 3 timepoints. Measurements were performed in duplicates.