Choosing MWCO For Dialysis Membrane - (Aug/21/2014 )

I'm developing a purification protocol which includes a dialysis step, which is intended to separate a 90kD protein from a 1 kD inhibitor. I have read that it's a good idea to choose a MWCO for the membrane that is about halfway between the two sizes, i.e., about 50 kDa. Does this sound correct? Would a lower MWCO likely be effective as well? Thanks.
 

never heard that "rule" (doesn't mean it isn't real). you should be able to use "standard" dialysis tubing with mwco of 12-14 kDa.

Thanks- I'll try it.

Use the highest MWCO you can that is still below your protein size. If you can find some with 30-50kDa MWCO, that would be ideal.

Having banged my head against the wall in a similar situation, I would recommend going through all the quality controls necessary to ensure all of your inhibitor is dialyzed away. If this inhibitor binds very tightly to your protein (low Kd), then it may be more difficult to get rid of than anticipated. Just be sure to check all of the inhibitor is really gone after dialysis, don't just assume it is.