Five aliquots of 50 ml of MyOne Streptavidin C1 Dynabeads (10 mg/ml suspension) were separated from their storage buffer and washed with twice with 50:50 methanol:water to remove potential mass spec contaminants. The beads were then washed with 1 Â Bind & Wash (B&W) buffer. B&W buffer for Dynabead incubation was made up according to the manufacturer's instructions: 20 mM Tris, pH 8.0, 2 mM EDTA, 2 M NaCl. Six aliquots of 20 ml (1 nmol) of stock solution of one biotinylated target was incubated with the Dynabeads. These aliquots were all made up to 40 ml with the addition of 20 ml of 2 Â B&W buffer. The biotinylated targets were then incubated at room temperature with the streptavidin beads for 1 h according to the manufacturer's instructions to immobilize the targets on the beads. The target solution was then removed from the beads and the beads were washed twice with hybridization buffer (20 mM Tris, pH 7.5, 10 mM MgCl 2 , 25 mM NaCl). A sixth aliquot of 100 ml of MyOne Streptavidin C1 Dynabeads was made up in the same way but this aliquot was incubated with 40 ml (2 nmol) of stock solution of the same biotinylated target and 40 ml of 2 Â B&W buffer.