Microtiter plate-based screening systems

In a particle concentration fluoroimmunoassay system that is based on microtiter plates with 0.22-/ filters on the bottoms, microparticles are used with a flowthrough wash system. Either fluorescein-labeled antibodies or cells serve as labels.(41) Car-boxyfluorescein diacetate, which crosses the cell membrane, is hydrolyzed by cytoplasmic esterases, thereby trapping carboxyfluorescein within the cell. The method is also useful for screening and isotyping antibodies. 

It is emphasized that in the case of kinetic resolution, the MS measurements must be performed in the appropriate time window (near 50% conversion). If this is difficult to achieve due to different amounts or activities of the mutants being screened in the wells of microtiter plates, the system needs to be adapted in terms of time resolution. This means that samples for MS evaluation need to be taken as a function of time. Finally, it is useful to delineate the possibility of multi-substrate ee screening using the MS-based assay, which allows for enzyme fingerprinting with respect to the enantioselectivity of several substrates simultaneously. 

UV/visual spectroscopy based on colorimetric assays is regularly used in low-throughput screens based on microtiter plates with a low density of wells (usually 96 wells per plate). Further increases in throughput by using high-density sample carriers has proven dilBcult for UV/visual spectroscopy detection systems. For most such applications, sample volume and thus... 

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