In-gel detection of biotin-protein conjugates with a green fluorescent streptavidin probeElectronic supplementary information (ESI) available: Figures S1-S4. See DOI: 10.1039/c4ay02666g

Exploitation of the (strept)avidin-biotin interaction is extremely valuable in a variety of biotechnological applications. Biotin is often covalently linked to proteins or nucleic acids. Determination of the degree of biotinylation of such macromolecules is essential for downstream applications. There is currently a gap in simple yet efficient assays for rapidly quantitating protein biotinylation, as staple methods may produce unclear results or rely on immuno- or competitive assays. We present a simple and reliable electrophoretic method to determine the relative extent of biotinylation of macromolecules. The method relies on complex formation between a biotinylated macromolecule and a streptavidin probe resulting in an electrophoretic mobility shift of the complex detectable by SDS-PAGE. Finally, a green fluorescent protein labelled streptavidin probe was developed to eliminate the need for staining and reduce assay time. A simple quantitative in-gel detection system was developed for measuring production of biotin-protein conjugates using a green fluorescent streptavidin probe.