Biotin-protein ratios and stability of biotinylated immunoglobulins as standards for the quantitation of biotin-binding immunoglobulins.

Biotin-binding IgG in human sera was quantitated using F(ab')(2)anti-human IgG-coated multiwell microplates (Muratsugu, M. el ah 2003, BioL Pharm. Bull., 26, 1605-1608). The biotin-protein ratio of biotinylated IgG, which was used as standard in the assay, was very important to quantitate the level of biotin-binding IgG. We investigated a synthesis method of biotinylated human immunoglobulins, how to determine the biotin-protein ratio of the biotinylated proteins, and their stability to prepare standards for measuring biotin-binding IgG, IgA, and IgM.