The invention is directed to a releasable conjugate comprising a biotinylated ligand (ligand1) having a biotin moiety, a ligand moiety, and a biotin-binding molecule (bbm) bound to the biotin moiety of the biotinylated ligand wherin the biotin moiety and the ligand moiety of the biotinylated ligand are separated by a spacer group consisting of polyethylene glycol according to the general formula Iwith n = 1 - 500, and X, Y = same or different, substituted or unsubstituted alkyl groups with 1 to 20 carbon atoms.Furthermore, the invention relates to a method for cleaving the releasable conjugate by providing biotin, streptavidin, or derivates thereof in a sufficient concentration to displace the biotin-binding molecule (bbm) from the biotin moiety of the biotinylated ligand.
