Colorimetric competitive inhibition method for the quantitation of avidin,streptavidin and biotin

A colorimetric competitive inhibition assay for avidin, streptavidin and bi otin was developed. The method for avidin or streptavidin was based on the competitive binding between avidin or streptavidin and a streptavidin-enzym e conjugate for biotinylated dextrin immobilized on the surface of a microt itre plate. For biotin quantitation the competition is between free biotin and the immobilized biotin for the streptavidin-enzyme conjugate. The limit s of detection which was determined as the concentration of competitor requ ired to give 90% of maximal absorbency (100% inhibition) was approximately 20 ng/100 mu l per assay for avidin and streptavidin and 0.4 pg/100 mu l pe r assay for biotin, The methods are simple, rapid, highly sensitive and ada ptable to high throughput analysis, (C) 1999 Elsevier Science B.V. All righ ts reserved.