Inhibition of Leishmania major N-myristoyltransferase using [3H]myristoyl-CoA and GCGGSKVKPQPPQAK(biotin)-amide as substrate preincubated for 5 mins prior substrate addition measured after 50 mins by streptavidin-coated scintillation proximity assay
Enzyme Inhibition Assay: Measurements were performed using a modification of the scintillation proximity assay platform described previously by Georgopapadakou, N. H. et al. (22nd International Congress on Chemotherapy, 2001, Abstract P16.001). Compounds were solubilised in DMSO at a top concentration of 10 mM and serially diluted in half log steps to achieve a range of final assay concentrations of 100 uM to 1 nM. Compound at each concentration (100-fold final) was added to white 384 well plates in a volume of 0.5 ml. Human, A. fumigatus, T. brucei or L. major N-myristoyl transferase enzyme, dissolved to a working concentration of 10 nM in assay buffer (30 mM Tris/HCl pH 7.4, 0.5 mM EGTA, 0.5 mM EDTA, 1.25 mM DTT, 0.1% Triton X-100), was then added to columns 1 to 11 and 13 to 23 of the plates in a volume of 20 ml. To columns 12 and 24, 20 ml assay buffer was added to provide a no enzyme control. Following a 5 minute incubation at room temperature the substrates (GCGGSKVKPQPPQAK(Biotin)-Amide and myristoyl coenzyme A), dissolved in assay buffer, were added to all wells in a volume of 20 ml to start the reaction. The final concentrations of peptide and 3H-myristoyl coenzyme A were 0.5 mM and 125 nM respectively and the specific activity of the radiolabel was 8 Ci/mmol. Plates were then incubated at room temperature for up to 50 minutes (dependant upon the period of linearity for the different enzyme species) before SPA beads, suspended to 1 mg/ml in a stop solution (200 mM Phosphoric Acid/NaOH pH 4, 750 mM MgCl2), were added in a volume of 40 ml.
Inhibition of N-terminal TEV cleavage site-fused His6 tagged Leishmania major NMT (11 to 421 residues) expressed in Escherichia coli Rosetta-2 cells using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay
Inhibition of Leishmania major NMT H398N/M420L/L421Q mutant expressed in Escherichia coli Rosetta-2 cells using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay
Inhibition of Leishmania major NMT H398N mutant expressed in Escherichia coli Rosetta-2 cells using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay
Inhibition of Leishmania major NMT M420L mutant expressed in Escherichia coli Rosetta-2 cells using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay
Inhibition of Leishmania major NMT L421Q mutant expressed in Escherichia coli Rosetta-2 cells using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay
Inhibition of N-terminal TEV cleavage site-fused His6 tagged Leishmania major NMT (11 to 421 residues) expressed in Escherichia coli rosetta2 cells at 500 uM using GSNKSKPK as substrate in presence of MyrCoA after 30 mins by CPM dye based fluorescence assay relative to control