If you are using affinity chromatography why can't you bind your protein
to a small amount of affinity matrix and step elute it into a very small
volume. I work with membrane proteins and keep the His tag on for
concentration and detergent exchange.
Concentration does not work very well for detergent containing samples.
Detergent micelles are often <90kDa and will not pass through membranes
(dialysis or concentrator). Monomers will pass through but micelles
take a long time to dissociate and pass though as monomers. You will
end up increasing your detergent concentration along with your protein
in most concentrating schemes.
--
Mark Bowen
