| Assay Method Information | |
| | GCS Enzymatic Assay |
| Description: | This assay was modified based on the study by Larsen et al. (J. Lipid Res. 2011, 53, 282). Madin-Darby canine kidney (MDCK) cell lysate was prepared using M-PER Mammalian Protein Extraction Reagent (Thermal Scientific) in the presence of a protease inhibitor cocktail (Roche). Protein concentration was determined using BCA assay kit (Pierce). Sixty micrograms of MDCK cell lysate was incubated with various concentrations of a compound described herein from 0.001 μM-10 μM, respectively, or as indicated in Table 2, in 100 mM Tris buffer (pH 7.5) containing 10 mM MgCl2, 1 mM dithiothreitol, 1 mM EGTA, 2 mM NAD, 100 μM UDP-glucose, 10 μM C6-NBD-Ceramide (Matreya LLC, Pleasant Gap, Pa.), 35 μM dioleoylphosphatidylcholine and 5 μM sulfatide (Sigma) in a final reaction volume of 100 μL at 37° C. for 1 hour. 0.1% DMSO was used as mock treatment or control. The reaction was terminated by adding 100 μL acetonitrile solution and subjected to LC/MS analysis.The quantitative analysis of NBD-Ceramide and glucosylceramide was performed on a Shimadzu ultra-fast liquid chromatography (Shimadzu, Japan) coupled with API 4000 triple quadrupole mass spectrometer (Applied Biosystems, Concord, Ontario, Canada). Sample separation was conducted on a Waters Xbridge BEH130 C18, 100 mm×4.6 mm i.d, 3.5 μm (Milford, Mass., USA). The mobile phase consisted of water and acetonitrile supplemented with 0.1% formic acid (v/v). The flow rate was 1.0 mL/min. The initial mobile phase was 20% acetonitrile and was ramped in a linear fashion to 50% acetonitrile in 0.4 min. From 0.4 to 1.5 min, the gradient was ramped to 98% acetonitrile, and then was held at 100% until 8.0 min. Acetonitrile was reset to 20% in 1.5 min, and maintained until 10.0 min. The total run time was 10.0 min. The MS/MS detection was performed in ESI positive mode. The mass transition of NBD-Ceramide was m/z 576.36→558.40 under the collision energy of 15 V, and the mass transition of glucosylceramide was m/z 738.35-558.40 under 21V collision energy. The cell lysate was diluted with equal volume of acetonitrile. Aliquots of 50 μL diluted samples were added to 1.5 mL tubes, and 100 μL of acetonitrile containing internal standard (100 ng/mL tolbutamide) were added for protein precipitation. The mixture were vortexed and then centrifuged at 13000 rpm for 10 min. 70 μL of supernatant were mixed with 140 μL of H2O and the final solution were injected for LC/MS/MS analysis and IC50's and/or percent inhibitions calculated. |
| Affinity data for this assay | |
|---|---|
| If you find an error in this entry please send us an E-mail | |