BEYOND THE 96-WELL MICROPLATE - INSTRUMENTS AND ASSAY-METHODS FOR THE384-WELL FORMAT

A new microplate scintillation and luminescence counter (TopCount(TM) HTS, Packard) has been developed for counting both 96- and 384-well mi croplates. The first assay methods tested in the 384-well plate were t he scintillation proximity assay and the luciferase reporter gene assa y. The binding curve and luciferase induction were identical in either plate format, The signal-to-noise ratio (maximum binding divided by n onspecific binding) in the 384-well plate is equal to or greater than those measured in the 96-well format resulting in a comparable assay w indow. Reagent pipetting for SPA, including the scintillating beads, w as performed with the MultiPROBE(TM) 104 Automated Liquid Handling Sys tem (Packard, Meridan, CT), This instrument has both the positioning a nd pipetting accuracy to support the 384-well microplate; therefore, m aking complete automation practical, With little or no optimization, b oth the SPA and the luciferase reporter gene assay could be miniaturiz ed to 50 mu l volumes or less.