Inhibition of Wistar/ST rat lung NAAA assessed as residual activity for conversion of [14C]PEA to [14C]palmitic acid at 100 uM after 20 mins relative to control
Non competitive inhibition of rat recombinant NAAA expressed in HEK293 cells assessed per mg of protein at 100 nM by Michaelis-Menten equation analysis
Non competitive inhibition of rat recombinant NAAA expressed in HEK293 cells assessed per mg of protein at 200 nM by Michaelis-Menten equation analysis
Inhibition of Sprague Dawley rat lung native NAAA enzyme using heptadecenoylethanolamide as substrate preincubated for 30 mins followed by substrate addition measured after 30 mins by UPLC-MS analysis
NAAA Assay: Recombinant NAAA or native rat lung NAAA was incubated at 37 °C. for 30 min in 0.2 ml of sodium hydrogen phosphate buffer (50 mM, pH 5.0) containing 0.1% Triton X-100, 3 mM dithiothreitol (DTT) and 50 mM heptadecenoylethanolamide as substrate. The reaction was terminated by the addition of 0.2 ml cold methanol containing 1 mmol of heptadecanoic acid (HDA, NuChek Prep, Elysian, Minn.). Samples were analyzed by LC/MS (liquid chromatography/mass spectrometry). Heptadecanoic acid was eluted on an XDB Eclipse C18 column isocratically at 2.2 ml/min for 1 min with a solvent mixture of 95% methanol and 5% water, both containing 0.25% acetic acid and 5 mM ammonium acetate. The column temperature was 50 °C. ESI was in the negative mode, capillary voltage was 4 kV, and fragmentor voltage was 100 V. N2 was used as drying gas at a flow rate of 13 liters/min and a temperature of 350 °C. Nebulizer pressure was set at 60 psi.
Enzymatic Assay: Lysosomal NAAA protein preparation were obtained by homogenizing male Sprague-Dawley rat lungs (Charles River) in 20 mM Tris-HCl buffer pH 7.4 containing 0.32M sucrose. Samples were centrifuged at 800×g for 15 minutes at 4° C. Supernatants were then centrifuged at 12,000 g for 30 minutes at 4° C. Pellets were then resuspended in PBS pH 7.4 and subjected to a freeze/thaw cycle at −80° C. The suspension was finally centrifuged at 105,000×g for 1 hour at 4° C. The supernatant was then used in the enzymatic assay.