How to establish the calibration curve of PNP in relation to concentrations in a microplate and for measuring the activity of lipase, what do we use?
Substrate stock: 20 mM p-NP palmitate in isopropanol.
Assay buffer: 50 mM Na2HPO4; 50 mM KH2PO4; 5 mM sodium deoxycholate and 1 g/L arabic gum, adjusted to pH 8 with NaOH.
p-NP standard stock solution: 20 mM p-nitrophenol in assay buffer. However, I always have an issue with the non-dissolution of arabic gum, which makes the blank cloudy and its OD higher than the other measured values for lipase