A sensitive microplate assay for glycoproteins that utilizes an immunological digoxigenin-based detection system

A sensitive microplate assay for glycoproteins, based on an immunological digoxigenin-based detection system, is described. When log absorbance was plotted against log concentration, linear standard curves were obtained over the range 25 ng/ml to 25 microliters/ml with bovine submaxillary mucin, porcine stomach mucin, fetal calf fetuin, asialofetuin and human transferrin. This detection limit and range are far superior to other assays that have been described. The use of the microtiter plate format means that a large number of samples can be assayed with ease. Due to the broad range of the assay, the concentration of the sample is not a particular problem, and samples above the upper cutoff value can be serially diluted in the microtiter plate to find an appropriate value.