I am doing a coIP, but I am stuck on a step with the protocol. The protocol is as follows:
Washing & Usage of Gamma binding beads
In a falcon tube, take 15 ml 1x (FS) PBS.
Take the Gamma-bind Sepharose beads from the fridge, shake it gently.
Cut a 1 ml pipette tip at the edge and pipette 100 µl of beads (for 2 tubes) from the stock and place it at the bottom of the PBS falcon tube. You need to adjust the number of beads to be taken, according to your experiment.
Spin the tube containing the beads in PBS at 2000g for 2 min.
Use a serological pipette to carefully remove the PBS until you reach 1 ml. Once you reach the 1 ml mark, use a fine tip (tips used for loading SDS-PAGE gels), insert the tip into the beads and remove the PBS until it's dry.
Add 1 ml of IP buffer to the beads, spin down the tubes at 2,000 g for 2 min and rotate it for 5 min. (Incubate on ice, when not on shaker).
In the last step (#6), should I discard the supernatant as the next step is to add the beads to antibody-lysate complex?
Should I try to scoop the beads from the bottom of the tube or should I take ~ 40-50 ul of the beads with the IP buffer and add it to my ab-lysate? If I use 40-50 ul, the rest of the beads with IP buffer can be discarded or can I store it at 4 degrees and use it for other experiments?