Evaluated for inhibition of enoyl acyl carrier protein reductase (FabI) of Staphylococcus aureus in the presence of NADH using crotonoyl CoA as substrate
Inhibition of Staphylococcus aureus recombinant FabI using trans-2-octenoyl N-acetylcysteamine thioester as substrate preincubated for 60 mins in presence of NADP+
Inhibition of Staphylococcus aureus recombinant FabI using trans-2-octenoyl N-acetylcysteamine thioester as substrate preincubated for 60 mins in presence of NADPH
Inhibition of Staphylococcus aureus FabI-mediated trans-2-octenoyl N-acetylcysteamine (t-o-NAC thioester) substrate reduction assessed as decrease in NADPH by ELISA
Inhibition of Staphylococcus aureus FabI assessed as reduction in inhibition of reduction of trans-2-octenoyl N-acetylcysteamine substrate by spectrophotometry
Inhibition Assay: The assay buffer AB contained 50 mM ADA (N-(2-acetamido)iminodiacetic acid monosodium salt) pH 6.5, 1 mM dithiothreitol, 0.006% Triton-X100 and 50 mM NaCl. The following components are added in a white polystyrene Costar plate (Ref 3912) up to a final volume of 55.5 uL: 1.5 uL DMSO or inhibitor dissolved in DMSO and 54 uL of a FabI/NADPH/NADP+ mixture in AB. After 60 min of pre-incubation at room temperature, the reaction is started by addition of 5 uL of trans-2-octenoyl N-acetylcysteamine thioester (t-o-NAC) to a final volume of 60.5 uL. This reaction mixture is then composed of 2 nM FabI, 40 uM NADPH (Sigma, N7505), 10 uM NADP+ (Sigma, N5755), 100 uM t-O-NAC and compound at defined concentration. Fluorescence intensity of NADPH (lamda=ex=360 nm, lamda=em=520 nm) is measured immediately after t-O-NAC addition (T0), and approximately 50 min later (T50) by a Fluostar Optima (BMG).
Fluorescence Based Assay: The assay buffer "AB" contained 50 mM ADA (N-(2-acetamido)iminodiacetic acid monosodium salt) pH 6.5, 1 mM dithiothreitol, 0.006% Triton-X100 and 50 mM NaCl. The following components are added in a white polystyrene Costar plate (Ref 3912) up to a final volume of 55.5 uL: 1.5 uL DMSO or inhibitor dissolved in DMSO and 54 uL of a FabI/NADPH/NADP+ mixture in AB. After 60 min of pre-incubation at room temperature, the reaction is started by addition of 5 uL of trans-2-octenoyl N-acetylcysteamine thioester (t-o-NAC) to a final volume of 60.5 uL. This reaction mixture is then composed of 2 nM FabI, 40 uM NADPH (Sigma, N7505), 10 uM NADP+(Sigma, N5755), 100 uM t-O-NAC and compound at defined concentration. Fluorescence intensity of NADPH (lamda=ex=360 nm, lamda=em=520 nm) is measured immediately after t-O-NAC addition (T0), and approximately 50 min later (T50) by a Fluostar Optima (BMG) so as to achieve ~30% of NADPH conversion.
Fluorescence Based Assay: Compound inhibitory activity of FabI enzyme is measured in vitro by the IC5 so determination using a fluorescence based assay.The protein FabI from S. aureus is prepared and purified using standard methods for recombinant protein expression after cloning of the gene in a prokaryotic expression vector.The biochemical activity of the FabI enzyme is assessed using the following method.The assay buffer AB contained 50 mM ADA (N-(2-acetamido)iminodiacetic acid monosodium salt) pH 6.5, 1 mM dithiothreitol, 0.006% Triton-X100 and 50 mM NaCl.The following components are added in a white polystyrene Costar plate (Ref 3912) up to a final volume of 55.5 uL: 1.5 uL DMSO or inhibitor dissolved in DMSO and 54 uL of a FabI/NADPH/NADP+ mixture in AB. After 60 min of pre-incubation at room temperature, the reaction is started by addition of 5 uL of trans-2-octenoyl N-acetylcysteamine thioester (t-o-NAC) to a final volume of 60.5 uL.
Inhibition of Staphylococcus aureus subsp. aureus Rosenbach ATCC 43300 FabI using crotonyl-CoA as substrate in presence of NADPH/NADH after 10 mins by fluorescence assay