Assay Method Information

Assay Name:  Enzymatic Activity Assay
Description:  The inhibition of purified recombinant human GAC by varying concentrations of inhibitors is assessed via a dual-coupled enzymatic assay. The glutamate produced by the glutaminase reaction is used by glutamate oxidase to produce α-ketoglutarate, ammonia, and hydrogen peroxide, with this hydrogen peroxide subsequently being used by horseradish peroxidase to produce resorufin in the presence of Amplex UltraRed. The assay buffer consisted of 50 mM Hepes (pH 7.4), 0.25 mM EDTA and 0.1 mM Triton X-100. GAC was incubated with potassium phosphate (10 minutes at room temperature) prior to incubation with inhibitor (10 minutes at room temperature). The final reaction conditions were as follows: 2 nM GAC, 50 mM potassium phosphate, 100 mU/mL glutamate oxidase (Sigma), 1 mM glutamine (Sigma), 100 mU/mL horseradish peroxidase (Sigma), 75 μM Amplex UltraRed (Life Technologies), and 1% (v/v) DMSO. The production of resorufin was monitored on a Perkin Elmer Envision plate reader (excitation 530 nm, emission 590 nm) either in a kinetics or endpoint mode (at 20 minutes). IC50 values were calculated using a four-parameter logistic curve fit.
Affinity data for this assay
 

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