ShiftAssay

ShiftAssay is a class of laboratory techniques used to detect shifts in the state of a biomolecular system caused by interactions, allosteric effects, or environmental changes. The term refers to assays whose readout changes as the target undergoes a binding event or conformational rearrangement, producing a detectable shift in signal, mobility, or optical properties.

In a typical ShiftAssay, a reporter or labeled target is incubated with test samples. Binding or activation alters the readout, which may be electrophoretic mobility in a gel-based format, fluorescence polarization or intensity, luminescence, or energy transfer efficiency in a FRET-based setup. The choice of readout defines whether the assay is best suited for solution-phase screening or gel-based separations.

Applications include characterizing protein–ligand and protein–nucleic acid interactions, monitoring conformational changes in enzymes or receptors, and supporting high-throughput screening campaigns in drug discovery and biomarker research.

Advantages include rapid analysis, low sample consumption, and compatibility with microplate formats; limitations involve potential labeling artifacts, background signals, and dependence on proper controls. Data are typically analyzed by fitting dose–response or binding curves to extract affinity constants or activity measures; assay quality is assessed with metrics such as the Z' factor.