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How to covalently couple proteins to carboxylate-modified magnetic beads

The convenient “one-step” protocol for covalent coupling of proteins to Sera-Mag™ carboxylate-modified particles or Sera-Mag™ SpeedBeads carboxylate-modified particles involves the following steps

1. Prepare a reagent mixture containing MES buffer, protein solution, and magnetic particles, and mix for 15 minutes at room temperature on a mixing wheel or other device.
2. Add freshly prepared EDAC solution at the pre-determined optimal concentration, and mix for one hour at room temperature on a mixing wheel or other device.
3. Pellet particles by centrifugation (10 to 30 minutes in a standard microcentrifuge) and decant the supernatant.
4. Perform two washes with MES buffer or a high pH buffer of your choice, pelleting particles by centrifugation and using ultrasonication to resuspend pellets between washes.
5. Resuspend final pellet to desired % solids with a buffer such as MES that does not contain blocking proteins.
6. Perform a BCA protein assay to determine the amount of protein bound on the particles.