Assay Method Information | |
| TR-FRET Assay |
Description: | The ability of some compounds of the present invention to inhibit POLRMT were determined in a homogeneous TR-FRET Assay using high-throughput screening in a 384-well plate format. This method is used to monitor the activity of mitochondrial transcription through measurement of its product, a 407 bp long RNA transcript. Detection of the product is facilitated by hybridization of two DNA-oligonucleotide probes to specific and adjacent sequences within the RNA product sequence. Upon annealing of the probes, two fluorophores are coupled directly to an acceptor nucleotide probe (ATTO647, 5′), or introduced via a coupled streptavidin with a biotinylated donor nucleotide probe (Europium cryptate) that is brought into sufficient proximity to serve as a fluorescence-donor-acceptor pair. Thus, a FRET signal at 665 nm is generated upon excitation at 340 nm.Proteins used as transcription factors (POLRMT: NP_005026.3, TFAM: NP_003192.1, TFB2M: NP_071761.1) are diluted from their stocks to working concentrations of 1 μM, 20 μM and 4 μM respectively, in a dilution buffer containing 20 mM Tris-HCl (pH 8.0), 200 mM NaCl, 10% (v/v) glycerol, 1 mM Dithiothreitol (DTT), 0.5 mM EDTA.DNA template is a pUC18 plasmid with the mitochondrial light strand promotor sequence (1-477) cloned between HindIII and BamHI sites. The DNA template is restriction linearized proximal to the promotor 3′-end (pUC-LSP).The reaction mixture (10 uL) containing 7.5 nM POLRMT, 15 nM of TFB2M, 30 nM of TFAM, 0.5 nM of DNA template and 500 μM nucleotide triphosphate mix (NTPs) in a reaction buffer (containing 10 mM Tris-HCl (pH 7.5), 10 mM MgCl2, 40 mM NaCl, 10 mM DTT, 0.005% (w/v) Tween-20, 160 units/ml Rnase inhibitor and 0.1 mg/mL BSA) are dispensed to compounds in microplates, using a Thermo Multidrop® dispenser, and incubated at 37° C. in a VWR INCU-Line incubator for 60 minutes after mixing. No nucleotide triphosphate mix is added to negative control samples. Microplates with compounds to be tested in the assay are prepared from 10 mM compound stocks in 100% DMSO, equal amounts of DMSO without any compound are added to positive control and negative control samples. |
Affinity data for this assay | |
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