A simplified scintillation proximity assay for fatty acid synthase activity: development and comparison with other FAS activity assays.

Fatty acid synthase (FAS), an essential enzyme for de novo lipogenesis, has been implicated in a number of disease states, including obesity, dyslipidemia, and cancer. to identify small-molecule inhibitors of FAS, the authors developed a bead-based scintillation proximity assay (SPA) to detect the fatty acid products of FAS enzymatic activity. this homogeneous SPA assay discriminates between a radiolabeled hydrophilic substrate of FAS (acetyl-coenzyme A) and the labeled lipophilic products of FAS (fatty acids), generating signal only when labeled fatty acids are present. the assay requires a single addition of unmodified polystyrene imaging SPA beads and can be miniaturized to 384- or 1536-well density with appropriate assay statistics for high-throughput screening. high-potency FAS inhibitors were used to compare the sensitivity of the SPA bead assay with previously described assays that measure FAS reaction intermediates (coa-SH and NADP(+)). the advantages and disadvantages of these different FAS assays in small-molecule inhibitor discovery are discussed. (Journal of Biomolecular Screening 2009:636-642)