| Assay Method Information | |
| | Inhibitory Activity using DGLA-CoA and Arachidonyl-CoA Mass Spectrometric Assays |
| Description: | Membrane preparations of D5D-overexpressing HEK293 6E cells were prepared in which the total protein concentration was 5.6 mg/mL. Stock D5D membrane preparations were diluted in D5D assay buffer (25 mM 2-amino-2-(hydroxymethyl)-1,3-propanediol, pH 7.5 containing 10 mM MgCl2, 1 mM octyl glucoside (SigmaAldrich 0-8001), 1 mM tris(2-carboxyethyl)phosphine hydrochloride (SigmaAldrich 646547)) to a final D5D membrane concentration of 10 μg/mL in an assay plate containing serially diluted test compounds. To 15 μL of this D5D preparation was added 15 μL of a substrate solution (0.25 mM NADH (nicotinamide adenine dinucleotide, Roche Diag. 10107735001), 0.25 mM adenosine triphosphate (SigmaAldrich A-3377), 0.05 mM coenzyme A hydrate (SigmaAldrich C-4282), and 0.01 mM DGLA (dihomo-g-linolenic acid, Sigma E-4504) in the same D5D assay buffer. After one-hour incubation at ambient temperature acetonitrile (30 μL) was added to quench the reaction and plates were centrifuged for 10 min @3,000 rpm. Mass spectrometric analysis involved a Rapidfire 360 SPE system coupled to an ABSciex API4000 Triple Quadrupole mass spectrometer using a C18 SPE cartridge (G9203-80105) with ionization in negative mode (solvent A=100% water; solvent B=100% acetonitrile, each solvent containing 5 mM ammonium acetate). DGLA-CoA and Arachidonyl-CoA were detected by multiple reaction monitoring (MRM) of the doubly charged parent ions at m/z 526.6 and 525.6, respectively. |
| Affinity data for this assay | |
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